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    Lilydale	Regional	Park	Slope	Failure	Investigation
    Lilydale	Regional	Park	
    Lilydale,	MN	
    NTI	Project	No.	 .            .   	


                               	
                        Prepared	for:	
                               	
                        Sara	Grewing	
                       City	of	St.	Paul	                      
                    	West	Kellog	Boulevard	
                            	City	Hall	
                     St.	Paul,	MN	       	
                              	
                              	
               August 21, 2013


               City of St. Paul
               15 West Kellog Boulevard
               400 City Hall
               St. Paul, Minnesota 55102


               Attn:       Ms. Sara Grewing

               Subject:    Lilydale Regional Park Slope Failure Investigation
                           Lilydale Regional Park - St. Paul, Minnesota
                           NTI Project No. 13.60260.800


               Dear Ms. Grewing:

               In accordance with your request and subsequent authorization, Northern Technologies, Inc.
               (NTI) conducted an investigation of the slope failure that occurred within the boundaries of the
               Lilydale Regional Park facility on May 22, 2013. Our work was performed in general accordance
               with Agreement # 02- of June 26, 2013.

               We appreciate the opportunity to have been of service on this project. If there are any questions
               regarding our review and recommendations, please contact us at (763) 433-9175.

               Northern Technologies, Inc.


               Marc D. Shannon, P.E
               President


               Ryan M. Benson, P.E.
               Senior Engineer




         st                        th                                                  th                      th
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Ramsey, MN 55303           St. Cloud, MN 53601     Mendota Heights, MN 55120      Fargo, ND 58103     Grand Forks, ND 58201
   763.433.9175                320.654.9409              651.389.4191              701.232.7288           701.219.0920
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                         TABLE OF CONTENTS
          LILYDAL REGIONAL PARK SLOPE FAILURE INVESTIGATION
                           Lilydale Regional Park
                            St. Paul, Minnesota
                        NTI Project No. 13.60260.800

                                                                                           Page

1.0    INTRODUCTION                                                                          1
       1.1  Site Description                                                                 1
       1.2  Scope of Service                                                                 1

2.0    EXPLORATION PROGRAM RESULTS                                                           2
       2.1  Exploration Scope                                                                2
       2.2  Subsurface Conditions                                                            2
       2.3  Ground Water Conditions                                                          2
       2.4  Laboratory Test Program                                                          3

3.0    GEOLOGICAL REVIEW                                                                     4
       3.1 Geologic Overview of the Quaternary                                               4
       3.2 Geologic Overview of the Decorah Shale Formation                                 10

4.0    CIVIL REVIEW OF NEAR SITE UTILITIES                                                  13

5.0    SLOPE STABILITY ANALYSIS                                                             14
       5.1  General Slope Stability - Background Information                                14
       5.2  Lilydale Regional Park Slope Failure Analysis                                   16

6.0    OPINION                                                                              19

7.0    CLOSURE                                                                              20

APPENDICES

      Appendix A -   Evaluation of Recovered Soil Samples, Field Exploration Procedures,
                     General Notes, Classification of Soils for Engineering Purposes
      Appendix B -   Site Location / Boring Logs
      Appendix C -   Cross Sections
      Appendix D -   Photos and Figures
      Appendix E -   Lab Testing
      Appendix F -   Bibliography
1.0.     INTRODUCTION

1.1.     Site Description
The site of the May 2013 Lilydale Regional Park slope failure under investigation is approximately
400 feet west of Cherokee Heights Boulevard in St. Paul, Minnesota. The area immediately
surrounding the slide area generally consists of a series of unmaintained hiking trails across
undulating terrain with steep slopes. The trail network in the immediate vicinity appears to
generally consist of a web of organically developed trails created by foot traffic and wildlife.
Many of these trails are highly eroded due to undulating terrain and steep slopes.

The area where the slope failure occurred is a horseshoe-shaped, near vertical slope surrounded
by adjacent bluff lines. The maximum surveyed elevation difference within the slide area was
approximately 60 feet. Many of the surrounding bluff lines visually appeared to have similar
elevation differences. A small stream of water was free falling from the southeast corner of the
horseshoe shaped slope. The topography in this area was likely partially developed during the
mining activities associated with the historic brick making activities.

In addition to the area under investigation NTI performed a cursory visual observation of the
adjacent bluff lines for signs of previous failures that were either undocumented or did not result
in documented losses. The surrounding area contains several bluff areas that have similar
topographic geometry and geologic composition. During the visual reconnaissance of the
surrounding area, multiple slides were observed with magnitudes of mass movement that were
similar in scale to the slide under investigation. The nearest similar observed slide was located in
close proximity to the slide under investigation. This slide was approximately 150 feet to the
north of the slide under investigation. NTI’s scope of work did not include the analysis of these
slides but they do indicate that the slide under investigation is not an isolated event within the
park or within the greater Mississippi River regional area that contains similar geologic
composition and topography.

Please refer to Appendix D for site photographs.

1.2      Scope of Services
The purpose of this report is to present a summary of our investigation and provide opinions
regarding the site conditions. Our scope of services was limited to the following:

1. Explore the project subsurface by means of 1 standard penetration boring/coring extending
   to an elevation approximately equal to the base of the failed slope. A single hand auger was
   also advanced from the top of the slope to practical hand auger refusal.
2. Determine the existing and pre-failure slope stability factor of safety.
3. Present the likely cause/causes of the failure.
4. Provide guidance as to the potential for future slope instability in the immediate slide area.



Page 1
Slope Failure Investigation
Lilydale Regional Park - St. Paul, Minnesota
NTI Project No. 13.60260.800



2.0      EXPLORATION PROGRAM RESULTS

2.1      Exploration Scope
A representative of NTI performed the subsurface exploration on June 8, 10 and 11 and July 10th
of 2013. Due to site access restrictions the nearest practical location for advancement of the
deep boring/coring was approximately 165 feet east of the slide area in the adjacent lawn area of
the Lilydale Regional Park. The hand auger was advanced immediately west of the slide area in
the nearest location practical while maintaining safety for the personnel.

Due to safety concerns detailed mapping of the jointing within the face of the shale/limestone
interbedded zone was not feasible. Detailed mapping of this zone was not of primary concern as
the near vertical overlying sands having a greater potential for failure and the failure zone under
investigation did not appear to extend deeply into the face of the weathered rock face. The
failure through this zone was near the interface between the sand overburden and upper,
weathered shale deposit (as assessed through observation and review of the debris field).

Cornerstone Land Surveying, Inc. was subcontracted to perfrom a topographical survey of the
slide area along with providing selected cross sections of the area under investigation. The survey
was completed utilizing the City of St. Paul datum.

2.2       Subsurface Conditions
Please refer to the boring/coring and the hand auger logs in Appendix C for detailed soil
descriptions and depths of stratum. The general geologic origin of retained soil samples is listed
on the boring logs.

The following generalized soil profile is an approximation developed by combing the information
gathered from hand auger and flight auger boring/coring performed at the project site as well as
from observation of conditions post failure. The soil / bedrock strata at/near the slope failure
appears to generally consist of thin zone of topsoil with rooted vegetation underlain by native
alluvial granular deposits overlying interbedded shale/limestone bedrock. Additional comment
on the evaluation of recovered soil samples is presented in Appendix A.

The drill crew backfilled the boreholes with auger cuttings or high solids bentonite grout to
comply with Minnesota Department of Health regulations. Minor settlement of the boreholes
will occur. The Owner is responsible for final closure of the boreholes.

2.3      Ground Water Conditions / Observation
The drill crew observed the boring for ground water 12 hours after the completion of drilling.
The groundwater at that time was recorded at 57.5 feet below existing grade which correlates to
the City of ‘St. Paul datum elevation 206.95. This and other observations and measurements are
noted on the boring log.

Observation post failure indicated localized “weeping” of ground water was occurring in the
general area of the interface between the overburden sand and weathered shale bedrock.


Page 2
Slope Failure Investigation
Lilydale Regional Park - St. Paul, Minnesota
NTI Project No. 13.60260.800



2.4      Laboratory Test Program
The analysis and recommendations in this report are based upon our visual soil classification, our
interpretation of the standard penetration resistance determined while sampling the soils,
laboratory testing as noted within the boring logs (Appendix E) and experience with similar soils.




                                                                                            Page 3
Slope Failure Investigation
Lilydale Regional Park - St. Paul, Minnesota
NTI Project No. 13.60260.800




3.0      GEOLOGICAL REVIEW
As part of the investigation NTI subcontracted with Foth Infrastructure & Environment, LLC to
provide a geological review of the overburden granular soils. Similarly, Summit Envirosolutions,
Inc. was retained to provide a geological review of the underlying limestone/shale bedrock zone.
These recognized experts within their fields of expertise were consulted to provide additional
background on the local depositional history and background into the natural weathering process
that occurs within these specific geological formations.

3.1      Geologic Overview of the Quaternary – Aged Landforms and the Strata of the
         Lilydale Regional Park Area (Text Provided by Dr. Curtis M. Hudak, Ph.D., P.G)

                                  Bedrock Geology and Buried Valleys
Modern valleys in and around the Lilydale Park area are carved into glacial drift and the
underlying Paleozoic bedrock. Relevant bedrock units are the gently dipping but beveled
Platteville Limestone, St. Peter Sandstone, Prairie du Chien Dolomite and Cambrian sandstones
that occur on the northern side of the Twin Cities structural basin. Carbonate units are resistant
and alternate with the more easily eroded sandstones, leading to escarpments along modern
valleys such as that marked by St. Anthony Falls on the Upper Mississippi Valley (UMV) above
the mouth of the Minnesota River Valley (MRV), and in buried paleolandscape positions. Along
the modern course of the Mississippi River, at and downstream of St. Paul, differential bedrock
resistance played a role during catastrophic flooding resulting in buried bedrock ledges that flank
a narrower inner flood channel.

Late Wisconsin glacial drift buries multiple generations of pre-existing bedrock valley segments
cut into these bedrock units. Some of the youngest bedrock valley segments maintain some
expression of relief on the modern land surface; however, most are buried without any hint of
surface expression. Those valleys not entirely filled are now completely abandoned or carry
underfit streams, or are occupied by a chain of lakes. Occupation, re-occupation, modification
and exhumation of different bedrock valley reaches varied spatially and temporally as glacial
advances, retreats and isostatic rebound altered river courses. Down-valley from St. Paul, the
modern UMV re-utilizes older bedrock valley reaches, although the bedrock valley morphology
has been altered by Late Wisconsin- and earliest Holocene-aged catastrophic floods. For the
most part, buried bedrock valley locations and fill sequences are only known from generalized
well-driller logs. Efforts to reconstruct the history of the buried bedrock drainage network
development have relied upon these logs (Schwartz, 1936; Bloomgren et al., 1990; Blumentritt et
al., 2009). Pre-Late Wisconsin glacial deposits have been recognized in the region (Matsch, 1972;
Baker et al., 1983; Hobbs et al., 1990). Most of these deposits have been interpreted from upland
landscape positions to the south, and buried bedrock valleys. Hudak et al. (2011) interpret at
least one stratigraphic unit in Rich Valley, a buried bedrock valley south-southeast of Lilydale in
nearby Dakota County, to be pre-Late Wisconsin in age.




Page 4
Slope Failure Investigation
Lilydale Regional Park - St. Paul, Minnesota
NTI Project No. 13.60260.800



                             Quaternary Geology and Catastrophic Floods
The Lilydale area was impacted by glacial lobes derived from distinct eastern (Labradorean) and
western (Keewatin) source areas of the Laurentide Ice Sheet in Canada (Figure 1A – Appendix
D). The Superior lobe (and related sublobes) advanced southwestward through the Lake
Superior basin, scouring iron- and copper-rich bedrock that imparts a reddish brown hue to its
glacial drift. Superior lobe till is further characterized by sandy loam diamicton textures and an
absence of Cretaceous shale clasts (Hobbs et al., 1990). A balance between ice flow and melting
was achieved to produce the St. Croix end moraine in and around the Twin Cities metropolitan
area sometime between 20,000 and 15,000 C14 yrs. B.P. (23,890 and 18,250 cal. yrs. B.P.[all
calibrated dates herein determined by CALIB 6.0.2]; Mickelson et al., 1983). The slightly younger
Des Moines lobe advanced southward through the Red River lowlands of western Minnesota,
then southeastward, building lateral moraines in western and northern Dakota County, and then
southward into Iowa. As the Des Moines lobe was stagnating in Iowa (Kemmis, 1991), the
Grantsburg Sublobe advanced northeastward, just north of the Twin Cities, about 11,900 C14 yrs.
B.P. (13,750 cal. yrs. B.P.; Wright and Rubin, 1956; Meyer, 1998; Hajic et al., 2009). Des Moines
lobe till is characterized by loam to clay loam diamicton textures, gray (fresh) to yellowish brown
to olive (oxidized) colors, and sparse to abundant Cretaceous shale clasts (Hobbs et al., 1990).
Moraines, till and outwash from advances of these three lobes occur in Ramsey and Dakota
counties near the Lilydale Park area (Figures 1A and 1B – Appendix D). Evidence presented by
Hudak et al. (2011) indicates that one or more tongues of Des Moines lobe ice extended beyond
its generally accepted ice margin limit.

Deglacial events were instrumental in shaping landscape elements of the valleys, as well as
establishing the baseline for Holocene landscape evolution. These deglacial events resulted in
buried paleolandscapes. Configuration of the modern MRV is primarily the result of one or
more catastrophic floods emanating from Lake Agassiz, an enormous proglacial lake that
occupied the Red River lowlands following retreat of the Des Moines lobe (Figure 1A –
Appendix D). Lake Agassiz drained southward through a broad spillway cut through the Big
Stone Moraine (of the Des Moines lobe) which forms the drainage divide between the Minnesota
and Red rivers (Figure 1A – Appendix D ). On geomorphic evidence, Hudak and Hajic (1999)
concluded that the incised MRV formed by catastrophic flooding, sharing many landforms
characteristic of spillway valleys formed or modified by deglacial catastrophic floods (Kehew and
Lord, 1986). MRV-forming catastrophic flood(s) pre-date 10,400 C14 yrs. B.P. (12,270 cal. yrs.
B.P.) based on several radiocarbon ages from the base of valley-bottom alluvial fans and
underlying fluvial deposits in the New Ulm and Mankato vicinities (Figure 1A – Appendix D;
Hudak and Hajic, 1999; Hudak and Hajic, 2005). Alluvial fans were deposited along the length of
the MRV as tributaries incised in response to the rapid cutting. Fisher (2003) used sedimentology
and radiocarbon ages from cores to determine that the spillway occupied by Big Stone Lake was
initially abandoned at its maximum depth of erosion around 10,800 C14 yrs. B.P. (12,700 cal. yrs.
B.P.). Lake Agassiz discharges later shifted to eastern and then northwestern outlets. The age of
initial catastrophic flooding that carved the MRV remains open to question, but had to occur
after the advance of the Grantsburg Sublobe, or about 11,900 C14 yrs. B.P. (13,750 cal. yrs. B.P.).
Fisher (2003) concluded that the spillway through the Big Stone Moraine was effectively inactive
between about 10,800 (12,700 cal. yrs. B.P.) and at least 9,920 C14 yrs. B.P. (11,320 cal. yrs. B.P.)
as indicated by a combination of absolute dates from: (1) lacustrine sediments within Big Stone
Lake; (2) valley-bottom strata within the MRV (Hudak and Hajic, 1999); and (3) forest elements


                                                                                               Page 5
Slope Failure Investigation
Lilydale Regional Park - St. Paul, Minnesota
NTI Project No. 13.60260.800



from the Lake Agassiz basin near Moorhead. That latter set of dates indicated that Lake Agassiz
was north of Moorhead at a relative low stand (Yansa et al., 2002) during the Moorhead Phase
(Fisher, 2003; Fisher et al., 2008). Additional radiocarbon ages that lend support to this
interpretation, particularly the ages of Yansa et al. (2002) and Yansa and Ashworth (2005), come
from approximately 17 km (10.6 miles) farther north of Moorhead in the Lake Agassiz basin near
Georgetown, MN, (Hudak and Hajic, 1999) and elsewhere in the basin (summarized in Fisher et
al., 2008).

The southern outlet was reactivated sometime between 9,900 and 9,400 C14 yrs. B.P. (11,300 and
10,630 cal. yrs. B.P.), but most likely initiation of this second phase of discharge occurred during
the last few centuries of this interval with little if any further incision of the Big Stone Lake
spillway (Fisher, 2003). Hudak and Hajic (1999) documented the preservation of older valley-
bottom alluvial fans and terraces (ca. 10,330-10,400 C14 yrs. B.P.; 12,170-12,270 cal. yrs. B.P.),
which lack evidence of catastrophically-carved paleochannels and therefore indicate that
subsequent Holocene-aged discharges were likely orders of magnitude less than the earlier
discharge that carved the MRV. This latter phase of flow(s) from Lake Agassiz must have been a
relatively low discharge, perhaps with seasonal fluxes.

Upstream from the MRV/UMV confluence, the Mississippi River was mostly a broad, braided
outwash stream that drained along the inner St. Croix glacial end moraine. Later the UMV was
supplied by outwash carried by the Grantsburg sublobe and Des Moines lobe meltwaters. Hajic
(2002) suggested that the Mississippi River may have debouched across the Anoka Sand Plain at
one point, and may have fed an earlier course of the St. Croix River until the Minneapolis North
Gap opened sometime between 11,400 and 11,800 C14 yrs. B.P. (13,270 and 13,640 cal. yrs. B.P.).
Catastrophic flow from Lake Agassiz down the MRV was augmented by the Mississippi River at
Fort Snelling and followed a new course to St. Paul, where it entered an old valley of the
Mississippi River, forming a waterfall over flat-lying Paleozoic rocks. The resulting waterfall
migrated upstream, and as it passed the confluence with the Mississippi River at Fort Snelling
about 10,800 C14 yrs. B.P. (12,700 cal. yrs. BP) the waterfall divided into two (Wright, H.E., Jr.,
personal communication). The Mississippi branch migrated upstream as St. Anthony Falls,
causing third-order falls to develop along its smaller tributaries, and remains visible near
downtown Minneapolis (Wright, 1972). The Minnesota River branch migrated upstream until it
reached the western edge of the Paleozoic caprock that maintained the waterfall (Wright, 1972).

         Mississippi River Valley Landscape Evolution in and near the City of St. Paul
Hudak (2008, 2010) interpreted that a complete Holocene-aged stratigraphic sequence from
10,000±40 C14 yrs. B.P. (11,470 cal. yrs. B.P.) is underlying the UMV floodplain in and near
downtown St. Paul (Figures 2A and 2B – Appendix D). Most strata found underlying the natural
and man-made levees/fills were approximately 24 m thick, and described as “gleyed alluvium and
wetland deposits.” Hudak documented that the radiocarbon ages within and between cores fall
into chronologic and stratigraphic order; and that two “wood twig” ages, one each from Core
08RA-02 and 08RA-01 approximately 780 feet apart and at nearly the same stratigraphic
elevation, have identical dates of 6,230±40 C14 yrs. B.P. (7,160 cal. yrs. B.P.; Beta-242059 and
Beta-242062). (Note: The term “fluvial” pertains to relatively higher energy, larger discharge
river processes; and “alluvial” pertains to relatively lower energy, smaller discharge river
processes.)

Page 6
Slope Failure Investigation
Lilydale Regional Park - St. Paul, Minnesota
NTI Project No. 13.60260.800



Definitive and substantial lake sediments were not identified in any of these core samples, nor
farther downstream between St. Paul and the Interstate-494 Wakota Bridge (Figures 2A and 2C –
Appendix D); Hudak, 2008, 2010; Trocki and Hudak, 2005). Blumentritt et al. (2009, p. 554) also
did not recognize the Lake Pepin, Lake Cannon, and Late Lake Vermillion strata at the Wakota
Bridge. These discrepancies might be explained by the finer-grained lacustrine strata (mostly silt
loams) being preserved in a three-dimensional mosaic pattern, and thus perhaps missed by most
cores; or, the Lake Pepin delta had concurrently prograded into the developing lake.

Hudak (2008) also interpreted “oxidized fluvial gravels” underlying the Holocene-aged sequence
mentioned above as deposits from Lake Agassiz’s waning catastrophic flood deposits. This
coarser sedimentary package is approximately 8-10 m thick, and the core samples were void of
datable materials. Stratigraphically bracketing dates from both above (10,000 ± 40 C14 yrs. B.P.
on wood; 11,470 cal. yrs. B.P.) and below (28,570±210 C14 yrs. B.P. [32,970 cal. yrs. B.P.] on
organic sediment and 34,170±400 C14 yrs. B.P. [39,160 cal. yrs. B.P.] on a carbon-stained root
trace) indicates that this coarse sedimentary package overlaps in time with the catastrophic phase
of discharge from the Agassiz basin.

Underlying the oxidized gravels are “gleyed fluvial gravels” (Hudak, 2008). Gleyed, fine sandy
loam and coarse silt loam were also interstratified within this generally coarser package. One
sediment date and one carbon trace date, which may also include small amounts of sediment,
were risked to confirm that these samples were possibly pre-dating the MRV catastrophic flood.
Sediment dates can be problematic because of detrital carbon causing ages to be too old, but it
was the only datable material available. A carbon trace of a root yielded an age of 34,170±400
C14 yrs. B.P. The other stratigraphically higher sediment sample yielded an age of 28,570±210 C14
yrs. B.P. Incomplete core recovery made determining possible stratigraphic discontinuities
impossible. Obviously the radiocarbon ages may not precisely date the deposit because of the
concern for detrital carbon. Heaving sands caused the boring to halt before reaching bedrock;
however, adjacent Mn/DOT geotechnical borings indicate that bedrock (Oneota Dolomite) is
consistently around the 171-174 m (560-570 ft.) elevation, which is only 1-4 meters (3.3-13 ft.)
deeper than the end of Hudak’s (2008) deepest boring.

Geomorphically beneath the Mounds Park bluff adjacent to the Warner Road Bridge crossing
over Childs Road is another study area that also contained a Holocene-aged sequence; albeit not
as uniformly consistent of depositional rates as the aforementioned Lafayette Bridge project area
(Figures 2A and 2C – Appendix D). If we were to strip all the “post-Euroamerican-aged
settlement” sediment off of both the Lafayette Bridge area floodplain and also the terrace
sediment assemblage geomorphically below us, then both terraces would be at the same elevation
of approximately 207-210 m (679-689 ft.; slight elevation differences are the result of channel
forms on the paleo-surface). Near-surface strata of both areas bear a weakly developed soil,
especially apparent when closer to the modern day active channel. The terrace sediment
assemblage at Childs Road is floored by a bedrock bench at 196-197 m (643-646 ft.) elevation.
The bedrock bench under Childs Road is approximately 21-26 m (69-85 ft.) higher in elevation
than the lowest bedrock elevations at the Lafayette Bridge crossing (171-174 m; 560-570 ft.). The
two lowermost sediment sequences found at the Lafayette Bridge project area are not well
represented at the Childs Road location, if at all, but rather are represented here locally by
sediments indicative of a suite of wetland, overbank, and minor lacustrine environments.


                                                                                             Page 7
Slope Failure Investigation
Lilydale Regional Park - St. Paul, Minnesota
NTI Project No. 13.60260.800



Hudak (2010) interprets the terrace sediment assemblage at Childs Road from top to bottom as
3-6 m (10-20 ft.) of “oxidized alluvium and overbank deposits” of post-Euroamerican settlement
age; overlying 10-11 m (33-36 ft.) of “gleyed fluvial and alluvial deposits”; overlying 1.5-3.0 m (5-
10 ft.) of “gleyed and unoxidized wetland, overbank, and lacustrine deposits;” overlying up to 0.5
m (1.6 ft.) of “gleyed fluvial deposits” such as rounded exotic gravels and angular local bedrock;
all overlying shale bedrock. Two wood samples each from different core samples yielded basal
ages (immediately above the bedrock bench) of 9,910±50 C14 yrs. B.P., and 9,400±40 C14 yrs. B.P.
(11,310 and 10,630 cal. yrs. B.P., respectively). These dates are consistent with the Lafayette
Bridge stratigraphic sequence that post-dates the MRV catastrophic flood gravels. The
uppermost recovered basal peat bed was matted with leafy matter, extremely compact and dense,
and yielded a radiocarbon date of 7,610±70 C14 yrs. B.P. (8,410 cal. yrs. B.P.); therefore the
“wetland/overbank/lacustrine depositional environments” lasted from approximately 9,900-
7,600 C14 yrs. B.P. (11,300-8,400 cal. yrs. B.P.). These differences in environments and elevations
indicate that while this environment existed on the bench from 9,900-7,600 C14 yrs. B.P., the
sedimentary depositional environments described at the Lafayette Bridge project area were
occurring geomorphically deeper in the valley trench. Shortly after 7,600 C14 yrs. B.P. (8,400 cal.
yrs. B.P.) the valley trench was apparently filled with enough sediment to cause the river waters to
overtop the once relatively stable bench environment at approximately 197 m (646 ft.) elevation.

Trocki and Hudak (2005) cored a natural levee on Pig’s Eye Island 3.2 km (2 mi) downstream
from the Childs Road bench project area (Figure 2A – Appendix D). They showed the
relationships between the overlying levee sediment assemblage and the underlying terrace
sediment assemblage. The levee sediment assemblage consisted of fine sand to fine loam. The
underlying terrace sediment assemblage consisted of gleyed medium to coarse fluvial sands with
thin, gleyed, laminar, silty clay loam overbank deposits. The boundary between the levee and
terrace sediment assemblages was identified in one location at a depth of 4.6 m (15-ft.) where it
was demarcated by an ash layer of burned peat, grasses, and fish bones. The charred peat plants
and ash yielded a radiocarbon date of 3,080±60 C14 yrs. B.P. (3,290 cal. yrs. B.P.).

Trocki and Hudak (2005) interpreted Pig’s Eye Island to be a three-dimensional mosaic
patchwork of different aged landforms, some of which were created during recent floods. The
island has seen both scouring in the form of crevasse splay channels breaching the natural levee,
and chutes behind the levee; and deposition in the form of splays and other overbank deposits.
The Pig’s Eye Island record demonstrates the dynamic geological and geomorphic character of
the Late Holocene in the UMV upstream of Lake Pepin.

                      Lilydale Core Description Summary and Interpretations
The Quaternary-aged strata of the Lilydale core are interpreted in broader terms, and are not
defined by specific geologic events such as the ice advances or catastrophic flooding described in
the previous paragraphs. More detailed analyses beyond the current scope of work would be
required to help definitively identify the lithostratigraphic units and depositional environments.
Examples of more detailed analyses might include rock and mineral identifications from the
core’s till samples, additional coring to better define the three-dimensional geometry of each
stratum, Optically Stimulated Luminescence (OSL) dating of the fluvial deposits, and fabric
studies on the till samples.


Page 8
Slope Failure Investigation
Lilydale Regional Park - St. Paul, Minnesota
NTI Project No. 13.60260.800



The Quaternary section of the Lilydale Core #1 has the following interpreted depositional
sequences starting from youngest (top) to oldest (bottom, or top of bedrock):

0.0-4.5 feet – mostly brown silt loams with faint bedding interpreted to be fine grained alluvium or
colluvially reworked loess.

6.6-24.5+ feet – mostly brown to dark brown fine sands to sandy loams with common pebbles
and weakly to moderately developed bedding all interpreted to be deposited by fluvial or glaciofluvial
processes.

26.6-27.0+ feet – brown silty clay loam to sandy clay loam with pebbles that is interpreted to be
fluvially or alluvially reworked till.

29.1-31.6 feet – brown sandy clay loam diamicton with subrounded pebbles all oriented in
parallel with a 45-50 degree dip and which is interpreted to be a glacial till.

31.6-31.7 feet – gravel lag deposit with an underlying thin iron oxidized sand bed.

31.7-39.5 feet – brownish yellow to yellowish brown fine to very coarse sand with few to
common pebbles interpreted to be fluvial deposits.

39.5-43.0+ feet – granite boulder that may represent a lag deposit.

44.7-45.0+ feet – brownish yellow sandy clay loam diamicton with pebbles interpreted to be a
glacial till.

46.6-47.0+ feet – brown to light yellowish brown coarse silt loam, which may be loess or
alluvially/colluvially reworked loess.

49.1-50.9+ feet – dark grayish brown clay loam diamicton to strong brown sandy clay loam
diamicton with traces of fabric all interpreted as either one or two glacial tills.

51.8-57.0+ feet – grayish brown to brownish gray fine sands and silt loams with weak bedding all
interpreted as alluvium or colluvium.

59.1-59.5+ feet – olive brown fine to coarse poorly sorted sands indicating a fluvial flood deposit.

60.2-60.5 feet – alternating and variably multicolored strata of silt loams, silty clay loams, and
sandy clay loams with thin bedding all indicating a fluvially-reworked bedrock.

60.5-61.0 feet – brown very coarse and angular sands consisting of fluvially-reworked local bedrock.

61.0 feet – shale bedrock; end of split-spoon sampling.




                                                                                                 Page 9
Slope Failure Investigation
Lilydale Regional Park - St. Paul, Minnesota
NTI Project No. 13.60260.800



                      Lilydale Geomorphology Summary and Interpretations
The Lilydale area of the MRV was most recently carved by catastrophic flood(s) coming from the
draining Glacial Lake Agassiz (Figure 1A – Appendix D). These catastrophic floods carved deep
into the pre-existing Quaternary-aged strata and the underlying Paleozoic bedrock sometime
between about 11,900 C14 yrs. B.P. (13,750 cal. yrs. B.P.) and 10,800 C14 yrs. B.P. (12,700 cal. yrs.
B.P.). This geologically young age range is based on several independent lines of evidence
presented by Fisher (2003), Hudak and Hajic (1999, 2005), and Hudak et al. (2011) as mentioned
in preceding paragraphs. In addition, Hudak (2008, 2010) interpreted that a complete Holocene-
aged stratigraphic sequence from 10,000±40 C14 yrs. B.P. (11,470 cal. yrs. B.P.) is underlying the
UMV floodplain in and near downtown St. Paul, just a short distance downstream from Lilydale
and the confluence of the Minnesota and Mississippi Rivers.

Geomorphically, the UMV at Lilydale is relatively young in appearance, as indicated by the
relatively steep valley bedrock walls, which have not yet had enough time to reach their angle of
repose. The Quaternary strata portions of the bluff walls in the Lilydale area (see Foth’s Core
Log #1) are also relatively steep, especially for a stratigraphic sequence of mostly unconsolidated
materials. The interpreted glacial tills (i.e., clay diamictons) represent the most erosional-resistant
units of the Quaternary-aged strata in the described core; and yet the erosion of any underlying
more unconsolidated coarser-grained strata would likely leave a small clay bed overhang for a
short time before its own weight took the clay overhang down. This process would eventually
continue until the angle of repose for each stratum was achieved in part and then finally together
as a whole slope consisting of multiple strata. This localized physical erosion may include
alluvial, colluvial, and eolian processes. The colluvial processes may include gravity, freeze-thaw
cycles, and sheetwash, for example. All of these geologic processes are normal and will continue
until the master valley wall reaches its angle of repose.

3.2       Geological Overview of the Decorah Shale Formation (Text Provided by Mr. Brian
          L. Gulbranson)
Summit observed the rock core provided by NTI that was obtained from a depth of 61.1 feet to
100 feet below the ground surface (bgs) that appeared to be comprised of a portion of the
Decorah Shale.

                                   General Decorah Shale Description
The Ordovician age Decorah Shale is the lowermost member of the Galena Group and is
conformably overlain by the Cummingsville Formation, another member of the Galena Group,
and is unconformably underlain by the Platteville Formation (Mossler, 2008). Both the
Cummingsville Formation and the Platteville Formation are carbonate lithic units of Ordovician
age. Age dating and correlation of a K-bentonite unit of the Decorah Shale give results of 454.2
million years ago (Sloan, 1987).

The Ordovician period marked a transition from a shallow-water environment where sand was
predominantly deposited to a deeper-water environment of dominantly carbonate deposition.
The result is that the Decorah Shale consists of both calcareous shale (containing marine fossils)
and thin layers of fossiliferous, gray, argillaceous limestone.


Page 10
Slope Failure Investigation
Lilydale Regional Park - St. Paul, Minnesota
NTI Project No. 13.60260.800



                                      General Rock Core Description
The rock core Summit observed contained limestone and shale that exhibited two distinct fabrics
as described below. Summit’s drill log description of the rock core is attaché (Appendix B)

The upper four feet (61.1 to 65 feet deep) of the rock core was observed to be limestone and
included a vertical to sub-vertical fracture (61.1 to 63.75 feet deep) indicating a highly fractured
zone or an extremely coincidental drilling location to have intersected this fracture in the two-
inch core. The remainder of the limestone portion of the core was generally thin-bedded and
parting was generally along horizontal bedding planes.

The remaining 35 feet of core (65 to 100 feet deep) was observed to be shale, K-bentonite, and
limestone. The clay mineral assemblage of the shale at the location cored is primarily illite, with
minor kaolinite and chlorite (Parham, 1966). The engineering properties of the shale of this
section are controlled by the fabric (preferred orientation of clay minerals) of the shale (Parham
and Austin, 1969). Summit noted two types of shale present in the core which represent two
types of fabric: a parallel to bedding orientation (exhibiting thin, wavy partings), and a random
orientation of clay minerals (exhibiting massive bedding). Parham and Austin (1969) use a playing
card analogy to describe these two types of fabric making it easy to visualize. The parallel to
bedding type is represented by a “deck of cards”, whereas the random orientation type is
represented by a “house of cards”.

According to Parham and Austin (1969), development of these fabrics is interpreted as being a
function of rate of accumulation of sediment and not a function of rock age or depth of burial.
The flocculation of clays entering a marine environment has been recognized since the 19th
century and it is assumed from the abundant marine fossils present in the Decorah Shale that the
clays forming this shale were deposited in a flocculated, or house-of-cards, type of environment.
During periods of rapid sediment accumulation, the individual clay minerals collapse under the
weight of the rapidly accumulating clay material above, rearranging the orientation of the platy
clay minerals into a deck-of-cards type of fabric. Periods of slow accumulation allow bonds
between the clay minerals to develop sufficient strength to resist the weight of the overlying
material, preserving the house-of-cards mineral orientation.

Where the platy clay minerals are oriented in the deck-of-cards arrangement, the shale will break
most commonly along the smooth surfaces parallel to bedding planes. The effect of clay mineral
orientation on permeability can be pronounced. Where the clay minerals are oriented parallel to
bedding, the permeability is very low perpendicular to the bedding plane surfaces, but the
permeability parallel to the bedding planes can be quite high. This occurs by water moving into
the air-dried shale along the bedding planes through capillary action. As the water moves into the
shale it drives air ahead into constricted spaces. The air exerts increasing pressure on increasingly
smaller constricted spaces as it is compressed by the advancing water. This force can pry mineral
contacts apart unless the clay minerals are extremely thin and flexible or the contacts well
cemented. Prying action of this type in a shale where there is a high degree of preferred clay
mineral orientation parallel to bedding plane surfaces cause expansion normal to the bedding
surface (Emerson, 1967).




                                                                                              Page 11
Slope Failure Investigation
Lilydale Regional Park - St. Paul, Minnesota
NTI Project No. 13.60260.800



Where there is a lack of preferred orientation to the clay minerals (house-of-cards arrangement),
the shale will not break smoothly parallel to normal bedding plane direction, but rather will break
along irregular surfaces (Parham and Austin, 1969). Water can infiltrate this random orientation
of clay minerals type of shale from any direction and may result in relatively small but equal
expansion in all directions (Emerson, 1967).

The ability of the Decorah Shale (irrespective of the limestone beds) to maintain a constant slope
on exposed cuts is partly a function of whether the natural moisture content of the shale can be
maintained. When the shale is exposed to drying conditions, air is able to move into the spaces
between clay minerals. During rainfall events, the air-dried shale will take water into its structure,
expand, and disaggregate via the mechanisms described above within a short time period
(Parham and Austin, 1969). Pieces of shale, loosened by the swelling action, travel downslope
exposing a fresh face or cut, which in turn dries and the process is repeated during the next
rainfall event.

This natural weathering and erosion cycle in addition to the yearly freeze/thaw cycle has the
effect of producing unstable slopes and undercut banks which, when overlain by incompetent
material as in the potentially fractured limestone present at this site (61 feet to 65 feet in the
core), may contribute to or produce slides when the undercutting proceeds beyond the capacity
of the material to support the weight above. As this drying and wetting, swelling and erosion
cycle continues, it is possible that additional slides may occur in the future.

Additionally, the K-bentonite beds have low shear strength when horizontal stresses become
large, and may act as a shear plane between more competent rocks above and below. With large
vertical loads the K-bentonite may squeeze out from between more competent beds, further
destabilizing the rock face.

To summarize, the natural weathering processes of the Decorah Shale present at the site likely
contributed to the slides that have occurred and may occur in the future.




Page 12
Slope Failure Investigation
Lilydale Regional Park - St. Paul, Minnesota
NTI Project No. 13.60260.800




4.0      CIVIL REVIEW OF NEAR SITE UTILITIES

                       Manmade and Natural Storm Water Runoff Drainage-
                          Ways within the Lilydale Regional Park Area
The following limited analysis is based on field observations and materials provided by the City
of St. Paul’s engineering staff including a drainage area map with a schematic of the storm sewer
system, aerial topographic contour mapping, and sheet 7 of 18 of St. Paul’s 2013 Citywide Sewer
Repairs Contract “A”. (Appendix B). No field surveys were conducted.
The residential neighborhood up-gradient (i.e. up-stream) of Lilydale Park is surface drained with
a series of catch basins, manholes and pipes culminating on the east side of Cherokee Heights
Boulevard in a stilling basin/energy dissipater. Storm water flowing from the energy dissipater
collects in a rip-rap lined swale along with storm water from two 12-inch pipes. The storm water
then flows under Cherokee Heights Boulevard via a 60-inch reinforced concrete pipe culvert.
From the end of the culvert to the river, storm water flows down a deep ravine cut into glacial
till. The bottom of this ravine is lined with natural boulders and manmade materials including
concrete rubble, bricks and vitrified clay, concrete and corrugated metal pipes. The longitudinal
slope of the upper 160 feet of the ravine is relatively steep, whereas the final 120 feet is relatively
flat with water flowing on top of the shale formation. The overall slope, based on provided aerial
topography, is approximately 30%. Near the area of the slide, the ravine ends with a 5 foot drop
into a pool and then a 30 foot waterfall to the bottom of the historic East Clay Pit.
The total contributory drainage area upstream of the 60-inch culvert is approximately 50 acres.
Assuming a time of concentration on the order of 20 minutes the peak flow would equal
approximately 100 cubic feet per second (“CFS”) during a 10 year rainfall and 150 CFS during a
100 year rainfall. A 10 year rainfall has a 10 percent probability of occurring in a given year
whereas the 100 year rainfall has a 1 percent probability. The above estimated storm water flow
volumes closely match the flow capacity of the 60-inch culvert.
Given the average slope and visually observed cross section, the velocity of runoff in the ravine
during peak events may exceed 20 feet per second (“FPS”). The native sands will begin to erode
at a velocity of approximately 2 FPS and the shale at 6 FPS. This explains the eroded channel
shown in the photos (Appendix D).
The width of the East Clay Pit near the water fall is 40 to 50 feet. Given an estimated velocity of
20 FPS and a drop of 30 feet it is possible for water to occasionally stream as far as the opposite
side, but this would occur so infrequently that it is unlikely this contributed to the observed slide.
At the time of the slide, construction was taking place on Cherokee Heights Boulevard above the
60 inch culvert. As shown on the plan sheet (Appendix D), this work included the removal and
replacement of existing catch basins, pipes, curbs and pavement. It is highly unlikely this type of
construction would produce seismic vibrations of such intensity as to cause failure of the slope.


                                                                                                Page 13
Slope Failure Investigation
Lilydale Regional Park - St. Paul, Minnesota
NTI Project No. 13.60260.800



5.0       SLOPE STABILITY ANALYSIS

As part of the investigation NTI has analyzed the area of the slope failure to determine, to the
extent practical, the likely factor of safety of the slope prior to failure as well as occurring at onset
of failure. These factors of safety are only a snapshot in time and vary as the moisture content of
the sand and shale, and the “apparent cohesion” of sand soils from rooted vegetation changes
over time (changes can occur due to natural events such as rainfall or man derived activity).

5.1       General Slope Stability - Background Information
Within the regional geology there are generally a few common types of slope failures. In order to
analyze the failure we must first understand the mechanics of the failure and the ground
movement associated with the failure.

1.    Surficial sloughing of the near surface soils: This type of sloughing generally does not generate
      a large soil mass and only results in minor changes to the slope geometry when taken as
      a single event.
2.    Deep seated circular failures: This type of failure is typical in low strength soils such as fat
      clays, swamp deposited soils and silts. Circular failures occur when the up slope mass
      creates a stress in the slope that cannot be compensated for by the down slope mass
      and the shear strength along the failure plane. This style of failure most often results in
      a raise in grade at the bottom of the slope.
3.    Block Failures: This style of failure can be identified by a movement of a mass of soil
      down slope in a block fashion and does not have a circular rotational component to the
      movement.
4.    Shear Plane Failure(s) through Faulted Bedrock: Weathered zones within bedrock as well as
      banded / layered plains within a sound bedrock profile can shear / fault leading. Water
      accumulation within such zones and any freezing during cold weather can widen prior
      cracks and move the rock mass. The resulting faulted bedrock mass can readily fail due
      to overburden loading and/or “self-weight”.

In NTI’s opinion, the slide under investigation was a block/shallow fault failure of the
weathered shale combined with surficial shear and sloughing of moist to wet, naturally
occurring overburden sand, a fault and failure process which appears to be common to
the area, as per observation of local topography.

Finally, in order to analyze the slope there has to be general understanding of the forces acting
upon the slope and how these relate to the resulting calculated factor of safety (FS) in regard to
the slope. In the most basic form the gravitational forces acting upon the individual soil particles
can be broken into two components. These being:

      A. A perpendicular force that is acting into the slope at a 90 degree angle and,
      B. A tangential component that is acting tangential to the slope.



Page 14
Slope Failure Investigation
Lilydale Regional Park - St. Paul, Minnesota
NTI Project No. 13.60260.800



The perpendicular gravitational component will aid in stabilizing the slope and resisting potential
slide failures. The tangential gravitational component results in a shear stress parallel to the
slope (i.e. shear face) that acts to draw the potential failure mass down the slope. The steeper
the slope the greater this shear stress becomes with a corresponding reduction in the
gravitational resisting force perpendicular to the slope.

Along with the gravitational stresses within the slope we must also consider the role of water
within the soil mass. The in-situ moisture content within the soil matrix can add to the stabilizing
shear strength or reduce the shear strength depending upon the porosity of the mass as well as
moisture content occurring at time of analysis (movement).

The overburden sand soils at this site are a frictional soil by nature. Meaning that the more
points of contact between the individual sand particles the greater the shear strength of the soil.
In addition, to this point to point contact the in-situ moisture content plays a role in the relative
shear strength of the soil. If we have moisture contents that are sufficient to provide a layer of
water around the sand particles but the sand particle remains in a drained condition we will have
an increase in strength from the surface tension of this water layer. We will consider this to be
one contributing component of apparent cohesion, a positive factor contributing to the shear
strength side of the equation.

However, if the moisture content were to increase rapidly so that we no longer had a fully
drained condition, an increase in the pore water pressure within the soil mass would occur,
resulting in a reduction in the normal force imparting point to point contact of the sand particles.
A continued increase in the ground water content of the sand would eventually cause excess pore
water pressure to develop within the voids occurring between sand particles, whereas the
resulting excess pressure would lessen the point to point contact of the sand particles, resulting in
a decrease to shear strength.

A simple analogy to the above is the construction of a sand castle. If the sand has insufficient
moisture, the particles will be frictional only in nature and will not have the benefit of the
apparent cohesion resulting from surface tension. This would be similar to trying to construct
your sand castle with dry sand that does not “hold together” [the maximum vertical angle that
could be constructed would be limited to the angle of repose of the dry sand].

If the moisture content of your sand used for the sand castle is too high, there would be a loss of
point to point contact of the sand particles. This may be seen as sand flowing away from the
base as water drains at the base of your sand castle.

If you strike the correct delicate balance of moisture content within the sand, construction of the
sand castle can be achieved as you maintain the point to point contact of the sand particles
combined with the benefit of surface tension provided by the moisture within the sand... The
completed sand castle will stand as long as the in-situ moisture content remains favorable and no
outside force is applied (like a wave or child pushing on the completed castle).




                                                                                               Page 15
Slope Failure Investigation
Lilydale Regional Park - St. Paul, Minnesota
NTI Project No. 13.60260.800



The final, more influential locally, and much more difficult-to-model force acting within the slope
is the role played by the vegetation root zone. These roots act as tiny soil nails essentially helping
to stable the overburden soil mass together. We have modeled such vegetation root growth
within the slope as a separate soil strata occurring along the face and top of the slope profile.
The strength of the composite root and sand zone realized through application of a second,
stronger apparent cohesion used to resist soil failure.

In summary, if we consider all the forces acting negatively on the slope to be shear stresses and the
combination of forces acting positively on the slope to be shear strength, then the corresponding
factor of safety of the slope can then be expressed by the following equation:

                                    FS = Shear Strength/Shear Stress

The FS of a slope that is standing yet inherently unstable and likely to fail at some point in the
future is considered to have a FS of 1.0. Further discussion on stability analysis of the failed
slope is presented within Section 5.2.

5.2       Lilydale Regional Park Slope Failure Analysis
In order to analyze the original slope, NTI had to approximate the original pre-failure slope
geometry. To such extent as possible, we utilized LIDAR map data, publicly available satellite
imagery and engineering judgment to estimate the cross section of the slope prior to failure. The
LIDAR cross sections were overlaid onto the post slide surveyed cross sections to generate a
before and after approximation. These are shown as lighter lines within the cross section
drawings of Appendix B. Due to the heavy tree cover and the undercut slopes, portions of the
LIDAR produced sections were considered inaccurate, thus we created a new section through the
failure using observation of adjacent natural slopes. This estimated original profile zone is shown
as a dashed line on Cross Section #4 (Appendix B). The resulting divergent profile between
Cross Section #4 and post failure survey section defines the probable failure surface of the slope.

In NTI’s opinion analysis of the slope pre-failure should be based on a marginally stable profile
having nominal 1.0 FS when assessed using consolidated drained [CD] soil shear strengths
amended to include apparent cohesion from water surface tension and root zone of vegetative
cover. Direct Shear testing of the overburden was used to establish the internal friction angle of
the sand. Similarly, ring shear testing was utilized to establish approximate friction angle and
residual friction angle of the shale formation. A moist unit weight of the sand and shale deposits
were established from laboratory samples and/or estimated based on correlation with other
parametric laboratory findings. Table 1 presents a summary of soil strength parameters used to
assess stability of the slope immediately prior to and at failure.

                                   Table 1: Soil Strength Parameters Note 1
                                                       Overburden Sand               Weathered
Parameter                                      (in root zone)   (beyond root zone)     Shale     Shale
Moist Unit Weight                 γm (pcf)         120                 120              140       150
Sat. Unit Weight                 γsat (pcf)        130                 130              145       155
Consolidated – Drained: S        C´ (psf)          300                 15               500      > 600
(C-D Triaxial)                   Φ´ (deg)          32                  32               24        26


Page 16
Slope Failure Investigation
Lilydale Regional Park - St. Paul, Minnesota
NTI Project No. 13.60260.800



                                    Table 1: Soil Strength Parameters Note 1
                                                       Overburden Sand               Weathered
Parameter                                      (in root zone)   (beyond root zone)     Shale          Shale
Consolidated – Drained             C´R (psf)       300                 15               400           > 500
(residual): S R (see discussion)   Φ´R (deg)        26                 26               16             16
Consolidated – Undrained: R        C´ (psf)        250                  0               500           > 600
(C-U Triaxial)                     Φ´ (deg)        32                  32               24             26
Note 1 Soil strength parameters established per soil strength tests and/or from correlation information provided
     by U.S. Army Corps of Engineering (COE) Engineering Manuals EM 1110-2-1906 “Laboratory Soil Testing”,
     EM 1110-2-1902 “Slope Stability”; and/or Naval Facilities Engineering Command, Design Manual 7.01, “Soil
     Mechanics” & Design Manual 7.02 “Foundations & Earth Structure”.

As our premise, soil strata for our analysis and corresponding phreatic water surface prior to and
at onset of slope failure is depicted by Figures 1A and 1B, respectively. Note herein that the
numerical modeling of the slope
utilized two dimensional “finite
difference” evaluation of slope
using FLAC Slope® software as
developed by H C Itasca. While
this powerful software can
virtually assess strength of any
profile, our observation of actual
failure provides basis for limiting
our assessment to the upper
portion of the slope / bedrock
feature. This and an additional
simplification of precluding any
undercut of the profile provides
basis of our analysis [i.e. any
minor protrusion of the shale
interface was excluded from the
overall assessment of slope as the
shear failure did not extend into
the protruding materials.
Depicted in Figures 1A and 1B
by the near vertical exclusion
zone established within the
weathered shale strata].

We reiterate it is our opinion per
observation that the natural slope
profile prior to collapse was likely
unstable and held solely in place
due to apparent cohesion
developed within the overburden
sand formation [from vegetation
root growth and capillary water

                                                                                                         Page 17
Slope Failure Investigation
Lilydale Regional Park - St. Paul, Minnesota
NTI Project No. 13.60260.800



surface tension]. Thus initial
assessment of the original
estimated profile was based on a
FS equal to 1.0. Figure 2 depicts
the areas of high strain rate
derived from this initial stability
assessment. The area of high
color banding of Figure 2 define
a profile slightly rearward of the
actual shear failure established by
comparative review of cross
sections (see previous
discussion).

We surmise local heavy
precipitation occurring
immediately prior to the shear
failure and collapse of slope
increased the water content and
elevation of the phreatic ground
water profile occurring within the
overburden sand. This would
have eliminated the apparent
cohesion caused by capillary
water tension, and increased pore
water pressure within the sand
soils. Both issues reduce shear
strength of the formation.

Such response was modeled
assigning consolidated –
undrained [CU] shear strength to
the respective “root zone” and
“non-root zone” overburden sand soils combined with increasing the phreatic water surface
profile occurring above the weathered shale. Such site conditions and corresponding stability
analysis findings are depicted by Figure 3 whereas the shear profile, as depicted by higher stress
levels, show a forward movement of a shear failure surface (i.e. left hand section of the Y shear
band occurring within the overburden sands – Figure 3). For the CU assessment, the FS falls
below unity and approaches a 0.8 finding, an unstable condition [as per premise of site conditions
and soil strength]. It is this forward branch of the shear ban which depicts the approximate
location of observed Lilydale slope failure.




Page 18
Slope Failure Investigation
Lilydale Regional Park - St. Paul, Minnesota
NTI Project No. 13.60260.800




6.0      OPINION

Based upon the completed analysis we conclude it is highly unlikely that recent “man-made”
activity contributed to the triggering the May 2013 slide event occurring within Lilydale Regional
Park. Contrary, in NTI’s opinion the two most likely failure mechanisms are as follows.

  1:     Due to additional ground water accumulation within the overburden alluvium (from
         recent rain events), the unit weight of the sand increased while any capillary tension
         benefit occurring at prior moisture content, if any, was lost. A majority of the water
         would have likely been concentrated directly on top but infiltrated any cracks occurring
         within the low permeable shale. The prior noted increase in soil mass, loss of
         beneficial capillary tension and water intrusion of the weathered shale would weaken
         the supported weathered zone, causing onset of shear and triggering shear collapse of
         the profile.

  2:     A second possible failure mechanism would be similar in nature with initial movement
         and shear occurring within the overburden sand layer as opposed to the weather shale.
         The increase in local ground water within the overburden sands would have caused an
         increase in pore water pressure within the sand matrix, lessening point to point contact
         of the grain structure and shearing under gravimetric load. The loss of shear strength
         within the sand profile would result in either “fluid like” cascade flow over the face of
         the weathered shale or cause increased loading and shear of the weathered shale strata.

Both of the above scenarios would produce a debris pile similar to the observed debris field at
the base of the failure. Regardless as to which triggered the failure, either scenario is the result
of changes occurring within the natural environment combined within ongoing weathering
impacts to the strata (root zone decay within the sand and/or water and ice damage of shale
deposit).

In conclusion, you should consider all bluff areas of similar geometry and geologic layers in and
around Lilydale Regional Park as being susceptible to this type of natural process and at risk
relative to collapse. Due to the many variables within this region it would be difficult to predict
with any certainty if, when, of what magnitude and where the next slide will occur. The only
variable that is predictable with a high level of certainty is that slopes of this nature, although
apparently stable to a non-professional, are inherently unstable, will undergo additional
weathering, and are highly likely to undergo failures of varying degrees in the future.




                                                                                                Page 19
Slope Failure Investigation
Lilydale Regional Park - St. Paul, Minnesota
NTI Project No. 13.60260.800




7.0        CLOSURE
Our opinions are based upon the available data assumed representative of the site. However, site
access limited us to only one boring and a hand auger. This report has been prepared for the
exclusive use of the City of St. Paul and its agents. Northern Technologies, Inc. has endeavored
to comply with generally accepted geotechnical engineering practice common to the local area.
Northern Technologies, Inc. makes no other warranty, express or implied.

Northern Technologies, Inc.
                                                       I herby certify that this plan, specification, or
                                                       report was prepared by me or under my direct
                                                       supervision and that I am a Duly Licensed
                                                       Professional Engineer under the Laws of the
Ryan M. Benson, P.E.                                   State of Minnesota.
Senior Engineer


                                                                      Ryan M. Benson
Steve Johnston, P.E.                                   Date: 8-21-2013         Reg. No. 42724
Vice President



Marc D. Shannon, P.E.
President


Bret R. Anderson, P.E.
Associate

RMB:ms:ba

Attachments
Lilydale Slide Investigation .doc




Page 20
APPENDIX A
         GEOTECHNICAL EVALUATION OF RECOVERED SOIL SAMPLES

We visually examined recovered soil samples to estimate distribution of grain sizes, plasticity,
consistency, moisture condition, and color, presence of lenses and seams, and apparent geologic
origin. We then classified the soils according using the Unified Soil Classification System (ASTM
D2488). A chart describing this classification system and general notes explaining soil sampling
procedures are presented within appendices attachments.
The stratification depth lines between soil types on the logs are estimated based on the available data.
Insitu, the transition between type(s) may be distinct or gradual in either the horizontal or vertical
directions. The soil conditions have been established at our specific boring locations only. Variations
in the soil stratigraphy may occur between and around the borings, with the nature and extent of such
change not readily evident until exposed by excavation. These variations must be properly assessed
when utilizing information presented on the boring logs.
We request that you, your design team or contractors contact NTI immediately if local conditions
differ from those assumed by this report, as we would need to review how such changes impact our
recommendations. Such contact would also allow us to revise our recommendations as necessary to
account for the changed site conditions.


                            FIELD EXPLORATION PROCEDURES


Soil Sampling – Standard Penetration Boring:
Soil sampling was performed according to the procedures described by ASTM D-1586. Using this
procedure, a 2 inch O.D. split barrel sampler is driven into the soil by a 140 pound weight falling 30
inches. After an initial set of six inches, the number of blows required to drive the sampler an
additional 12 inches is recorded (known as the penetration resistance (i.e. “N-value”) of the soil at the
point of sampling. The N-value is an index of the relative density of cohesionless soils and an
approximation of the consistency of cohesive soils.


Soil Sampling – Power Auger Boring:
The boring(s) was/were advanced with a 6 inch nominal diameter continuous flight auger. As a result,
samples recovered from the boring are disturbed, and our determination of the depth, extend of various
stratum and layers, and relative density or consistency of the soils is approximate.


Soil Classification:
Soil samples were visually and manually classified in general conformance with ASTM D-2488 as
they were removed from the sampler(s). Representative fractions of soil samples were then sealed
within respective containers and returned to the laboratory for further examination and verification of
the field classification. In addition, select samples were submitted for laboratory tests. Individual
sample information, identification of sampling methods, method of advancement of the samples and
other pertinent information concerning the soil samples are presented on boring logs and related report
attachments.
                                                       General Notes
             DRILLING & SAMPLING SYMBOLS                                            LABORATORY TEST SYMBOLS
SYMBOL              DEFINITION                                          SYMBOL        DEFINITION
 C.S.               Continuous Sampling                                   W           Moisture content-percent of dry weight
 P.D.               2-3/8” Pipe Drill                                     D           Dry Density-pounds per cubic foot
 C.O.               Cleanout Tube                                         LL, PL      Liquid and plastic limits determined in
                                                                                      accordance with ASTM D 423 and D 424
  3 HSA                 3 ¼” I.D. Hollow Stem Auger                       Qu          Unconfined compressive strength-pounds per
                                                                                      square foot in accordance with ASTM D
                                                                                      2166-66
  4 FA                  4” Diameter Flight Auger
  6 FA                  6” Diameter Flight Auger
  2½C                   2 ½” Casing
  4C                    4” Casing                                                  Additional insertions in Qu Column
  D.M.                  Drilling Mud                                      Pq         Penetrometer reading-tons/square foot
  J.W.                  Jet Water                                         S          Torvane reading-tons/square foot
  H.A.                  Hand Auger                                        G          Specific Gravity – ASTM D 854-58
  NXC                   Size NX Casing                                    SL         Shrinkage limit – ASTM 427-61
  BXC                   Size BX Casing                                    pH         Hydrogen ion content-meter method
  AXC                   Size AX casing                                    O          Organic content-combustion method
  SS                    2” O.D. Split Spoon Sample                        M.A.*      Grain size analysis
  2T                    2” Thin Wall Tube Sample                          C*         One dimensional consolidation
  3T                    3” Thin Wall Tube Sample                          Qc*        Triaxial Compression
                                                                                     * See attached data Sheet and/or graph

                                                  Water Level Symbol
Water levels shown on the boring logs are the levels measured in the borings at the time and under the conditions indicated. In sand,
the indicated levels can be considered reliable ground water levels. In clay soils, it is not possible to determine the ground water
level within the normal scope of a test boring investigation, except where lenses or layers of more pervious water bearing soil is
present and then a long period of time may be necessary to reach equilibrium. Therefore, the position of the water level symbol for
cohesive or mixed soils may not indicate the true level of the ground water table. The available water level information is given at
the bottom of the log sheet.

                                               Descriptive Terminology
                          DENSITY                                                      CONSISTENCY
          TERM                          “N” VALUE                       TERM                               “N” VALUE
          Very Loose                          0-4                       Soft                                     0-4
          Loose                               5-8                       Medium                                   5-8
          Medium Dense                      9 – 15                      Rather Stiff                            9 – 15
          Dense                            16 – 30                      Stiff                                  16 – 30
          Very Dense                       Over 30                      Very Stiff                             Over 30
          Standard “N” Penetration: Blows per foot of a 140 pound hammer falling 30 inches on a 2 inch OD split spoon.

          Relative Proportions                                                         Particle Sizes
      TERMS                      RANGE                         Boulders                     Over 3”
       Trace                       0-5%                        Gravel - Coarse              ¾” – 3”
       A little                    5-15%                                 Medium             #4 – ¾”
       Some                        15-30%                      Sand - Coarse                #4 - #10
       With                        30-50%                                Medium             #10 - #40
                                                                         Fine               #40 - #200
                                                               Silt and Clay                Determined by plasticity characteristics.
                                                               Note: Sieve sizes are U.S. Standard.
Classification of Soils for Engineering Purposes
ASTM Designation D-2487 and D 2488 (Unified Soil Classification System)

                                                                                                        Group
Major Divisions                                                                                                    Typical Names                                                                                                         Classification Criteria
                                                                                                        Symbols
                                                                                                              Well –graded gravels
                                                                                                                                                                                                                                                                  Cu = D60 / D10                                        greater than 4.
                                                                                        Clean Gravels
                                                                                                              and gravel-sand
                                                                                                        GW
                                            50% or more of coarse fraction




                                                                                                                                                                                                                                                                  Cz = (D30)2 / (D10 x D60)




                                                                                                                                                                                             requiring use of duel symbols.
                                                                                                              mixtures, little or no                                                                                                                                                                                    between 1 & 3.
                                                                                                              fines.
                                                                                                              Poorly graded gravels




                                                                                                                                                                                             Borderline Classification
                                            retained on No. 4 sieve.




                                                                                                              and gravel-sand
                                                                                                        GP    mixtures, little or no
                                                                                                                                                                                                                                                                  Not meeting both criteria for GW materials.




                                                                                                                                                                                             GW, GP, SW, SP
                                                                                                                                                                                             GM, GC, SM, SC
                                                                                                              fines.
                                                                                                                                                                                                                                                                  Atterberg limits




                                                                                                                                           Classification on basis of percentage of fines.
                                                                                                              Silty gravels, gravel-                                                                                                                                                                             Atterberg limits plotting
                                                                                                        GM                                                                                                                                                        below “A” line, or
                                                                                 Gravels with




                                                                                                              sand-silt mixtures.                                                                                                                                                                                in hatched area are
                                                                                                                                                                                                                                                                  P.I. less than 4.
                                            Gravels




                                                                                                                                                                                                                                                                                                                 borderline
More than 50% retained on No. 200 sieve *




                                                                                                                                                                                                                                                                  Atterberg limits
                                                                                 Fines




                                                                                                              Clayey gravels, gravel-                                                                                                                                                                            classifications requiring
                                                                                                        GC    sand-clay mixtures.
                                                                                                                                                                                                                                                                  above “A” line with                            use of dual symbols.
                                                                                                                                                                                                                                                                  P.I. greater than 7.




                                                                                                                                                                                             From 5% to 12% passing No. 200 Sieve:
                                                                                                                                                                                             More than 12% passing No. 200 Sieve:
                                                                                                                                                                                             Less than 5% passing No. 200 Sieve:
                                                                                                              Well-graded sands and
                                                                                                                                                                                                                                                                  Cu = D60 / D10 greater than 6.
                                                                                        Clean Sands




                                                                                                        SW    gravelly sands, little or
                                                                                                              no fines.                                                                                                                                           Cz = (D30)2 / (D10 x D60) between 1 & 3.
                                            fraction passes No 4 sieve.
                                            More than 50% of coarse




                                                                                                              Poorly-graded sands
Course Grained Soils




                                                                                                        SP    and gravelly sands, little                                                                                                                          Not meeting both criteria for SW materials.
                                                                                                              or no fines.
                                                                                                                                                                                                                                                                  Atterberg limits
                                                                                                              Silty sands, sand-silt                                                                                                                              below “A” line, or                             Atterberg limits plotting
                                                                                                        SM    mixtures.
                                                                                 Sands with




                                                                                                                                                                                                                                                                  P.I. less than 4.                              in hatched area are
                                                                                                                                                                                                                                                                                                                 borderline
                                            Sands




                                                                                                                                                                                                                                                                  Atterberg limits
                                                                                 Fines




                                                                                                              Clayey sands, sand-                                                                                                                                                                                classifications requiring
                                                                                                        SC                                                                                                                                                        above “A” line with
                                                                                                              clay mixtures.                                                                                                                                                                                     use of dual symbols.
                                                                                                                                                                                                                                                                  P.I. greater than 7.
                                                                                                              Inorganic silts, very fine
                                                                                                        ML    sands, rock flour, silty                                                                                                                                     Plasticity Index Chart
                                                            Liquid Limit of 50% or




                                                                                                              or clayey fine sands.                                                                                 60
                                                                                                              Inorganic clays of low to
                                                            Silts and Clays




                                                                                                              medium plasticity,                                                                                                         Chart f or classif icat ion of f ine gr ained soils
                                                                                                                                                                                                                    50                   and t he f in f ract ion of coar se gr ained soils.
                                                                                                        CL    gravelly clays, sandy                                                                                                                                                                               CH Soils
                                                                                                              clays, silty clays, lean                                                                                                   At t er ber g Limit s plot t ing in hat ched area are

                                                                                                              clays.                                                                                                40
                                                                                                                                                                                                                                         border line classif icat ions r equiring use of dual
                                                                                                                                                                                                 Plasticity Limit




                                                                                                                                                                                                                                         symbols.

                                                                                                              Organic silts and
                                                            less




                                                                                                        OL    organic silty clays of
                                                                                                              low plasticity.                                                                                       30
                                                                                                              Inorganic silts,                                                                                                                            CL Soils
More than 50% passes No. 200 sieve *




                                                                                                                                                                                                                                                                                                                                     " A" Line
                                                                                                              micaceous or                                                                                          20
                                                            Liquid Limit greater than




                                                                                                        MH    diatomaceous fine
                                                                                                              sands or silts, elastic
                                                                                                                                                                                                                                                                                                                             OH & M H Soils
                                                                                                              silts.                                                                                                10
                                                            Silts and Clays




                                                                                                                                                                                                                                             CL-M L Soils

                                                                                                              Inorganic clays of high                                                                                                                                              OL & M L Soils
                                                                                                        CH    plasticity, fat clays.                                                                                   0
                                                                                                                                                                                                                                     0          10             20             30               40     50    60       70         80            90   100
Fine Grained Soils




                                                                                                              Organic clays of                                                                                                                                                                   Liquid Limit
                                                            50%.




                                                                                                        OH    medium to high
                                                                                                              plasticity.
                                                            Organic
                                                            Highly




                                                                                                              Peat, muck and other
                                                                                                        Pt
                                                            Soils




                                                                                                              highly organic soils.
APPENDIX B
                                                                                                                                                                                   Northern Technologies, Inc.
                                                                                                                                                                                   1408 Northland Drive, Suite 107
                                                                                                                                                                                                                                                                                             BORING NUMBER HA-1
                                                                                                                                                                                   Mendota Heights, MN 55120                                                                                                                                         PAGE 1 OF 1
                                                                                                                                                                                   651-389-4191



                                                                                                                                                                CLIENT City of St. Paul                                                         PROJECT NAME Lilydale Slide
                                                                                                                                                                PROJECT NUMBER 13.60260.800                                                     PROJECT LOCATION Lilydale, MN
                                                                                                                                                                DATE STARTED 7/10/13                                 COMPLETED 7/10/13          GROUND ELEVATION 199.68 ft                                     HOLE SIZE 3 inches
                                                                                                                                                                DRILLING CONTRACTOR NTI                                                         GROUND WATER LEVELS:
                                                                                                                                                                DRILLING METHOD Hand Auger                                                            AT TIME OF DRILLING --- No groundwater observed.
                                                                                                                                                                LOGGED BY RL                                         CHECKED BY RMB                   AT END OF DRILLING ---
                                                                                                                                                                NOTES N-Value estimated via Dynamic Cone Penotrometer (DCP)                           AFTER DRILLING ---
                                                                                                                                                                                                                                                                                                                                             ATTERBERG




                                                                                                                                                                                                                                                                                                                                                                            FINES CONTENT
                                                                                                                                                                                                                                                          SAMPLE TYPE




                                                                                                                                                                                                                                                                                                               DRY UNIT WT.
                                                                                                                                                                                                                                                                        RECOVERY %




                                                                                                                                                                                                                                                                                                 POCKET PEN.
                                                                                                                                                                                                                                                                                                                                               LIMITS




                                                                                                                                                                                                                                                                                                                              CONTENT (%)
                                                                                                                                                                                                                                                                                                                               MOISTURE
                                                                                                                                                                                                                                                                                     (N VALUE)
                                                                                                                                                                         GRAPHIC




                                                                                                                                                                                                                                                            NUMBER




                                                                                                                                                                                                                                                                                      COUNTS




                                                                                                                                                                                                                                                                                                                                                               PLASTICITY
                                                                                                                                                                DEPTH




                                                                                                                                                                                                                                                                                       BLOW
                                                                                                                                                                                                                                                                           (RQD)
                                                                                                                                                                           LOG




                                                                                                                                                                                                                                                                                                                   (pcf)




                                                                                                                                                                                                                                                                                                                                                     PLASTIC
                                                                                                                                                                                                                                                                                                     (tsf)




                                                                                                                                                                                                                                                                                                                                                                                  (%)
                                                                                                                                                                  (ft)




                                                                                                                                                                                                                                                                                                                                            LIQUID
                                                                                                                                                                                                              MATERIAL DESCRIPTION




                                                                                                                                                                                                                                                                                                                                                                 INDEX
                                                                                                                                                                                                                                                                                                                                             LIMIT

                                                                                                                                                                                                                                                                                                                                                      LIMIT
GEOTECH BH COLUMNS - REVISED DATA TEMPLATE_7-20-12.GDT - 8/14/13 12:21 - C:\USERS\RACHELL\DESKTOP\GNIT FILES\LILYDALE SLIDE_7-10-13\LILYDALE SLIDE (H.A.).GPJ




                                                                                                                                                                 0.0
                                                                                                                                                                                      2" TOPSOIL
                                                                                                                                                                                                                                                               HA
                                                                                                                                                                                      SILTY SAND - (SP), fine to medium grained, trace roots, trace                                     8
                                                                                                                                                                                                                                                                1
                                                                                                                                                                                      gravel, brown, moist, loose to dense

                                                                                                                                                                                                                                                               HA                       7                                         4

                                                                                                                                                                                      NOTE: Trace shale below 1 foot
                                                                                                                                                                                                                                                               HA
                                                                                                                                                                                                                                                                                        8
                                                                                                                                                                                                                                                                2


                                                                                                                                                                                                                                                               HA                       6                                         5                                            20


                                                                                                                                                                                                                                                               HA
                                                                                                                                                                                                                                                                                       11
                                                                                                                                                                                                                                                                3
                                                                                                                                                                 2.5

                                                                                                                                                                                                                                                               HA                      17                                         6

                                                                                                                                                                                      NOTE: Cobbles at 3 feet
                                                                                                                                                                                                                                                               HA
                                                                                                                                                                                                                                                                                       14
                                                                                                                                                                                                                                                                4


                                                                                                                                                                                                                                                               HA                                                                 6


                                                                                                                                                                                                                                                               HA
                                                                                                                                                                                                                                                                5


                                                                                                                                                                                                                                                               HA
                                                                                                                                                                 5.0
                                                                                                                                                                                      NOTE: Occasional shale fragments at 5 feet
                                                                                                                                                                                                                                                               HA
                                                                                                                                                                                                                                                                                                                                  7                                            23
                                                                                                                                                                                                                                                                6

                                                                                                                                                                                      SHALE - gray
                                                                                                                                                                                                                                                               HA
                                                                                                                                                                                                                                                                7

                                                                                                                                                                                                               Boring terminated at 6.0 feet.
                                                                                                                                                           Northern Technologies, Inc.
                                                                                                                                                           1408 Northland Drive, Suite 107
                                                                                                                                                                                                                                                                          BORING NUMBER SB-1
                                                                                                                                                           Mendota Heights, MN 55120                                                                                                                                              PAGE 1 OF 3
                                                                                                                                                           651-389-4191



                                                                                                                                        CLIENT City of St. Paul                                                          PROJECT NAME Lilydale Slide
                                                                                                                                        PROJECT NUMBER 13.60260.800                                                      PROJECT LOCATION Lilydale, MN
                                                                                                                                        DATE STARTED 6/8/13                                    COMPLETED 6/12/13         GROUND ELEVATION 264.45 ft                                         HOLE SIZE 5" Casing inches
                                                                                                                                        DRILLING CONTRACTOR STS Enterprises LLC                                          GROUND WATER LEVELS:
                                                                                                                                        DRILLING METHOD 3 1/4 in. H.S.A.                                                          AT TIME OF DRILLING ---
                                                                                                                                        LOGGED BY RTM                                          CHECKED BY RMB                     AT END OF DRILLING 58.00 ft / Elev 206.45 ft Taken in morning.
                                                                                                                                        NOTES See below for casing and sampling notes                                             AFTER DRILLING 57.50 ft / Elev 206.95 ft Taken in morning (6/12/13).
                                                                                                                                                                                                                                                                                                                          ATTERBERG




                                                                                                                                                                                                                                                                                                                                                         FINES CONTENT
                                                                                                                                                                                                                                      SAMPLE TYPE




                                                                                                                                                                                                                                                                                            DRY UNIT WT.
                                                                                                                                                                                                                                                    RECOVERY %




                                                                                                                                                                                                                                                                              POCKET PEN.
                                                                                                                                                                                                                                                                                                                            LIMITS




                                                                                                                                                                                                                                                                                                           CONTENT (%)
                                                                                                                                                                                                                                                                                                            MOISTURE
                                                                                                                                                                                                                                                                  (N VALUE)
                                                                                                                                                 GRAPHIC




                                                                                                                                                                                                                                        NUMBER




                                                                                                                                                                                                                                                                   COUNTS




                                                                                                                                                                                                                                                                                                                                            PLASTICITY
                                                                                                                                        DEPTH




                                                                                                                                                                                                                                                                    BLOW
                                                                                                                                                                                                                                                       (RQD)
                                                                                                                                                   LOG




                                                                                                                                                                                                                                                                                                (pcf)




                                                                                                                                                                                                                                                                                                                                  PLASTIC
                                                                                                                                                                                                                                                                                  (tsf)




                                                                                                                                                                                                                                                                                                                                                               (%)
                                                                                                                                          (ft)




                                                                                                                                                                                                                                                                                                                         LIQUID
                                                                                                                                                                                      MATERIAL DESCRIPTION




                                                                                                                                                                                                                                                                                                                                              INDEX
                                                                                                                                                                                                                                                                                                                          LIMIT

                                                                                                                                                                                                                                                                                                                                   LIMIT
                                                                                                                                          0
                                                                                                                                                              6" TOPSOIL
                                                                                                                                                                                                                                           SS                     2-2-2-2
                                                                                                                                                              FILL: CLAY, trace roots, brown, moist, medium                                           50
                                                                                                                                                                                                                                            1                       (4)
                                                                                                                                                                                                                                           HS
                                                                                                                                                                                                                                           SS                     2-2-5-6
                                                                                                                                                                                                                                                      58
GEOTECH BH COLUMNS - REVISED DATA TEMPLATE_7-20-12.GDT - 8/21/13 13:25 - C:\USERS\PUBLIC\DOCUMENTS\BENTLEY\GINT\PROJECTS\LILYDALE.GPJ




                                                                                                                                                                                                                                            2                       (7)
                                                                                                                                          5                                                                                                HS
                                                                                                                                                              FILL: POORLY GRADED SAND WITH A LITTLE SILT - (SP-SM),                       SS                     6-6-9-9
                                                                                                                                                                                                                                                      67
                                                                                                                                                              fine to medium grained, trace gravel, brown, dry, medium dense to             3                      (15)
                                                                                                                                                              dense                                                                        HS
                                                                                                                                                                                                                                           SS                    9-12-15
                                                                                                                                                              5" Casing from 0 to 8 feet                                                             100
                                                                                                                                                                                                                                            4                      (27)
                                                                                                                                                              4" Casing from 8 to 41 feet
                                                                                                                                         10                                                                                                HS
                                                                                                                                                              CLAYEY SAND - (SC), fine to medium grained, trace gravel,                                          12-12-12-
                                                                                                                                                              brown, moist, dense to very dense                                            SS
                                                                                                                                                                                                                                                      92            15
                                                                                                                                                                                                                                            5
                                                                                                                                                                                                                                                                   (24)
                                                                                                                                                                                                                                          RW
                                                                                                                                                                                                                                          SS                     12-16-18
                                                                                                                                                                                                                                                     100
                                                                                                                                                                                                                                           6                       (34)

                                                                                                                                         15                                                                                               RW
                                                                                                                                                                                                                                           SS                     9-11-9
                                                                                                                                                                                                                                                     100
                                                                                                                                                                                                                                            7                      (20)
                                                                                                                                                                                                                                          RW
                                                                                                                                                              POORLY GRADED SAND WITH A LITTLE SILT - (SP-SM), fine
                                                                                                                                                              to medium grained, trace gravel, brown, moist, dense                         SS                    5-7-9-11
                                                                                                                                                                                                                                                      63
                                                                                                                                                                                                                                            8                      (16)
                                                                                                                                         20                                                                                               RW
                                                                                                                                                                                                                                          SS                      8-10-8
                                                                                                                                                                                                                                                      83
                                                                                                                                                                                                                                           9                       (18)
                                                                                                                                                                                                                                          RW

                                                                                                                                                                                                                                           SS                    10-9-8-11
                                                                                                                                                                                                                                                      63
                                                                                                                                                                                                                                           10                      (17)
                                                                                                                                                              CLAYEY SAND - (SC), fine to medium grained, trace gravel,
                                                                                                                                         25                   brown, moist, medium dense                                                  RW
                                                                                                                                                                                                                                           SS                     8-7-7-9
                                                                                                                                                                                                                                                      75
                                                                                                                                                                                                                                           11                      (14)
                                                                                                                                                                                                                                          RW
                                                                                                                                                              SANDY CLAY - (CL), trace gravel, brown to gray, moist, stiff                 SS                    5-8-10-12
                                                                                                                                                                                                                                                     100
                                                                                                                                                                                                                                           12                       (18)
                                                                                                                                         30                                                                                               RW
                                                                                                                                                              POORLY GRADED SAND WITH A LITTLE SILT - (SP-SM), fine                       SS                     8-11-13
                                                                                                                                                              to coarse grained, trace gravel, light brown, waterbearing, dense                       89
                                                                                                                                                                                                                                          13                       (24)
                                                                                                                                                              to very dense                                                               RW

                                                                                                                                                                                                                                                                 12-18-18-
                                                                                                                                                                                                                                           SS
                                                                                                                                                                                                                                                      92            20
                                                                                                                                                                                                                                           14
                                                                                                                                                                                                                                                                   (36)
                                                                                                                                         35                                                                                               RW
                                                                                                                                                                                             (Continued Next Page)
                                                                                                                                                           Northern Technologies, Inc.
                                                                                                                                                           1408 Northland Drive, Suite 107
                                                                                                                                                                                                                                                                          BORING NUMBER SB-1
                                                                                                                                                           Mendota Heights, MN 55120                                                                                                                                             PAGE 2 OF 3
                                                                                                                                                           651-389-4191



                                                                                                                                        CLIENT City of St. Paul                                                          PROJECT NAME Lilydale Slide
                                                                                                                                        PROJECT NUMBER 13.60260.800                                                      PROJECT LOCATION Lilydale, MN
                                                                                                                                                                                                                                                                                                                         ATTERBERG




                                                                                                                                                                                                                                                                                                                                                        FINES CONTENT
                                                                                                                                                                                                                                     SAMPLE TYPE




                                                                                                                                                                                                                                                                                           DRY UNIT WT.
                                                                                                                                                                                                                                                   RECOVERY %




                                                                                                                                                                                                                                                                             POCKET PEN.
                                                                                                                                                                                                                                                                                                                           LIMITS




                                                                                                                                                                                                                                                                                                          CONTENT (%)
                                                                                                                                                                                                                                                                                                           MOISTURE
                                                                                                                                                                                                                                                                 (N VALUE)
                                                                                                                                                 GRAPHIC




                                                                                                                                                                                                                                       NUMBER




                                                                                                                                                                                                                                                                  COUNTS




                                                                                                                                                                                                                                                                                                                                           PLASTICITY
                                                                                                                                        DEPTH




                                                                                                                                                                                                                                                                   BLOW
                                                                                                                                                                                                                                                      (RQD)
                                                                                                                                                   LOG




                                                                                                                                                                                                                                                                                               (pcf)




                                                                                                                                                                                                                                                                                                                                 PLASTIC
                                                                                                                                                                                                                                                                                 (tsf)




                                                                                                                                                                                                                                                                                                                                                              (%)
                                                                                                                                          (ft)




                                                                                                                                                                                                                                                                                                                        LIQUID
                                                                                                                                                                                      MATERIAL DESCRIPTION




                                                                                                                                                                                                                                                                                                                                             INDEX
                                                                                                                                                                                                                                                                                                                         LIMIT

                                                                                                                                                                                                                                                                                                                                  LIMIT
                                                                                                                                         35
                                                                                                                                                              POORLY GRADED SAND WITH A LITTLE SILT - (SP-SM), fine                       SS                    12-14-16
                                                                                                                                                              to coarse grained, trace gravel, light brown, waterbearing, dense                      89
                                                                                                                                                                                                                                          15                      (30)
                                                                                                                                                              to very dense (continued)
                                                                                                                                                                                                                                         RW
                                                                                                                                                                                                                                         SS          83         20-50/0"
                                                                                                                                                                                                                                         16

                                                                                                                                         40                                                                                              RW
                                                                                                                                                              NOTE: Granite boulder from 39.5 to 43 feet.


                                                                                                                                                              5 1/8" diameter rock bit from 0 to 41 feet                                  RC
                                                                                                                                                              3 7/8" diameter rock bit from 41 to 41.5 feet
                                                                                                                                                              Reamed boulder with 3 7/8" diameter core barrel                                                   20-21-23-
                                                                                                                                                                                                                                          SS
GEOTECH BH COLUMNS - REVISED DATA TEMPLATE_7-20-12.GDT - 8/21/13 13:25 - C:\USERS\PUBLIC\DOCUMENTS\BENTLEY\GINT\PROJECTS\LILYDALE.GPJ




                                                                                                                                                                                                                                                    100            41
                                                                                                                                                              SANDY CLAY - (CL), trace gravel, brown to gray, moist, very stiff           17
                                                                                                                                         45                                                                                                                       (44)
                                                                                                                                                                                                                                          SS                    15-30-33
                                                                                                                                                                                                                                                    100
                                                                                                                                                                                                                                          18                      (63)
                                                                                                                                                                                                                                         RW
                                                                                                                                                                                                                                                                15-25-40-
                                                                                                                                                                                                                                          SS
                                                                                                                                                                                                                                                     75            60
                                                                                                                                                                                                                                          19
                                                                                                                                                                                                                                                                  (65)
                                                                                                                                         50                                                                                              RW
                                                                                                                                                                                                                                         SS                     15-30-50
                                                                                                                                                                                                                                                    100
                                                                                                                                                                                                                                         20                       (80)
                                                                                                                                                              POORLY GRADED SAND - (SP), very fine grained, brown,                       RW
                                                                                                                                                              waterbearing, very dense
                                                                                                                                                                                                                                                                25-35-30-
                                                                                                                                                                                                                                          SS
                                                                                                                                                                                                                                                     88            35
                                                                                                                                                                                                                                          21
                                                                                                                                                                                                                                                                  (65)
                                                                                                                                         55                                                                                              RW
                                                                                                                                                                                                                                         SS                     15-30-40
                                                                                                                                                                                                                                                    100
                                                                                                                                                                                                                                         22                       (70)
                                                                                                                                                              POORLY GRADED SAND - (SP), fine to medium grained, trace                   RW
                                                                                                                                                              gravel, brown, waterbearing, very dense
                                                                                                                                                                                                                                                                30-35-38-
                                                                                                                                                                                                                                          SS
                                                                                                                                                                                                                                                     92            50
                                                                                                                                                                                                                                          23
                                                                                                                                                                                                                                                                  (73)
                                                                                                                                         60                                                                                              RW
                                                                                                                                                              WEATHERED SHALE OCCASIONALLY INTERBEDDED WITH                              SS          50           50/4"
                                                                                                                                                              LIMESTONE                                                                  24
                                                                                                                                                              30% water loss while coring                                                RB


                                                                                                                                                              NX Casing was set from 0 to 61 feet and cleaned out with 2 15/16"           RC
                                                                                                                                                                                                                                                     90
                                                                                                                                                              rock bit                                                                    25
                                                                                                                                         65                   NX 2 15/16" core barrel sampling from 61 to 71, and 73 to 100 feet
                                                                                                                                                              After sitting overnight with broken diamond bit at 71 feet, hole was
                                                                                                                                                              cleaned out on 6-11-13 with rock bit from 71 to 73 feet.
                                                                                                                                                              100% water loss and 1 broken diamond bit while coring from 66 to
                                                                                                                                                              71 feet

                                                                                                                                                                                                                                          RC
                                                                                                                                                                                                                                                     80
                                                                                                                                                                                                                                          26
                                                                                                                                         70


                                                                                                                                                                                                                                          RB
                                                                                                                                                                                                                                                                                                            16           43       16         27
                                                                                                                                                                                                                                          27
                                                                                                                                                              0.5 hrs to core from 73 to 78 feet.

                                                                                                                                         75
                                                                                                                                                                                             (Continued Next Page)
                                                                                                                                                           Northern Technologies, Inc.
                                                                                                                                                           1408 Northland Drive, Suite 107
                                                                                                                                                                                                                                                                           BORING NUMBER SB-1
                                                                                                                                                           Mendota Heights, MN 55120                                                                                                                                               PAGE 3 OF 3
                                                                                                                                                           651-389-4191



                                                                                                                                        CLIENT City of St. Paul                                                               PROJECT NAME Lilydale Slide
                                                                                                                                        PROJECT NUMBER 13.60260.800                                                           PROJECT LOCATION Lilydale, MN
                                                                                                                                                                                                                                                                                                                           ATTERBERG




                                                                                                                                                                                                                                                                                                                                                          FINES CONTENT
                                                                                                                                                                                                                                        SAMPLE TYPE




                                                                                                                                                                                                                                                                                             DRY UNIT WT.
                                                                                                                                                                                                                                                      RECOVERY %




                                                                                                                                                                                                                                                                               POCKET PEN.
                                                                                                                                                                                                                                                                                                                             LIMITS




                                                                                                                                                                                                                                                                                                            CONTENT (%)
                                                                                                                                                                                                                                                                                                             MOISTURE
                                                                                                                                                                                                                                                                   (N VALUE)
                                                                                                                                                 GRAPHIC




                                                                                                                                                                                                                                          NUMBER




                                                                                                                                                                                                                                                                    COUNTS




                                                                                                                                                                                                                                                                                                                                             PLASTICITY
                                                                                                                                        DEPTH




                                                                                                                                                                                                                                                                     BLOW
                                                                                                                                                                                                                                                         (RQD)
                                                                                                                                                   LOG




                                                                                                                                                                                                                                                                                                 (pcf)




                                                                                                                                                                                                                                                                                                                                   PLASTIC
                                                                                                                                                                                                                                                                                   (tsf)




                                                                                                                                                                                                                                                                                                                                                                (%)
                                                                                                                                          (ft)




                                                                                                                                                                                                                                                                                                                          LIQUID
                                                                                                                                                                                      MATERIAL DESCRIPTION




                                                                                                                                                                                                                                                                                                                                               INDEX
                                                                                                                                                                                                                                                                                                                           LIMIT

                                                                                                                                                                                                                                                                                                                                    LIMIT
                                                                                                                                         75
                                                                                                                                                              WEATHERED SHALE OCCASIONALLY INTERBEDDED WITH
                                                                                                                                                              LIMESTONE (continued)                                                          RC
                                                                                                                                                                                                                                                        81
                                                                                                                                                              700 gallons of water used from 71 to 85 feet                                   28
                                                                                                                                                              50% water loss while coring

                                                                                                                                                              0.5 hrs to core from 78 to 79.5 feet.

                                                                                                                                         80                   1.2 hrs to core from 79.5 to 84.5 feet.                                                                                                         14           52       19         33


                                                                                                                                                                                                                                             RC
                                                                                                                                                                                                                                                        97
                                                                                                                                                                                                                                             29
GEOTECH BH COLUMNS - REVISED DATA TEMPLATE_7-20-12.GDT - 8/21/13 13:25 - C:\USERS\PUBLIC\DOCUMENTS\BENTLEY\GINT\PROJECTS\LILYDALE.GPJ




                                                                                                                                         85



                                                                                                                                                              60 gallons of water loss from 84.5 to 92 feet
                                                                                                                                                                                                                                             RC
                                                                                                                                                                                                                                                        73
                                                                                                                                                                                                                                             30

                                                                                                                                         90




                                                                                                                                                              50 gallons of water loss from 92 to 100 feet

                                                                                                                                         95
                                                                                                                                                                                                                                             RC
                                                                                                                                                                                                                                                       100
                                                                                                                                                                                                                                             31




                                                                                                                                        100
                                                                                                                                                                                     All shale and limestone drilled hard.
                                                                                                                                                                                     Voids or soft layers were not sensed with drill.
                                                                                                                                                                                     Very slow drilling with low downward pressure in
                                                                                                                                                              shale.
                                                                                                                                                                                     Borehole backfilled with neat cement grout.
                                                                                                                                                                                     Boring terminated at 100.0 feet.
Core/Profile: Lilydale Core #1
Location: Northing 147504.8050 – Easting 570917.7170
Legal description: SW¼ SE¼ SE¼ Section 12 T28N R23W
County: Ramsey
Parent material: Glaciofluvial
Vegetation: Unknown
Slope: Unknown
Elevation: 958.71 feet (292.2 meters) NAVD 88 Datum
Remarks: Hollow-stem auger with discontinuous split-spoon sampling. Drillers reported drilling through a granite
boulder at 39.5-43.0 feet depth. All samples were moist unless noted otherwise. Core described by Curtis M.
Hudak on June 27, 2013.

Depth                    Horizon
(feet)                   or Zone      Description
1.6-1.8                       C       very dark grayish brown (10YR3/2) silt loam to loam; few medium distinct
                                      strong brown (7.5YR4/6) mottles; massive to very weak thin platy
                                      structure; friable; non-effervescent; abrupt lower boundary; faint bedding
                                      may be indicative of sheetwash, alluvial/colluvial. NTI Sample #1.
1.8-2.0                       C       alternating brown to dark brown (7.5YR4/4) and dark brown (7.5YR3/2)
                                      coarse silt loams; weak thin laminar bedding; friable; non-effervescent;
                                      unknown lower boundary; laminar beds are of the same textures but
                                      different colors and suggest transport of materials from nearby upslope
                                      sources, alluvial/colluvial. NTI Sample #1.
4.1-4.5                       C       yellowish brown (10YR5/4-5/6) silt loam; few fine distinct strong brown
                                      (7.5YR4/6) mottles; very weak traces of laminar bedding; friable; non-
                                      effervescent; unknown lower boundary; common fine rootlets; one
                                      subangular metamorphic pebble lower boundary, alluvial/colluvial. NTI
                                      Sample #2.
6.6-7.0                       C       pink (7.5YR7/4 dry; brown to dark brown 7.5YR4/4 when moistened) fine
                                      sand with few fine pebbles; single grain; loose; slight effervescence;
                                      unknown lower boundary; one coarse angular possibly fossiliferous pebble,
                                      fluvial. NTI Sample #3.
9.1-9.5                       C       brown (7.5YR5/4) fine loamy sand with pebbles; single grain; weak thin
                                      bedding; very friable to loose; strong effervescence; unknown lower
                                      boundary; coarse pebbles are angular sandstones; fine pebbles are
                                      subrounded metamorphics. NTI Sample #4.
11.6-12.0                     C       alternating brown (7.5YR5/4; saturated) fine sand thin bedding and dark
                                      brown to brown (7.5YR4/4; saturated) sandy loam medium beds; sandy
                                      loam medium beds part to thin beds; fines sands are loose; sandy loams are
                                      very friable; strong effervescence; unknown lower boundary; single
                                      subrounded 1.75”x1.25”x1.0” red granite pebble, fluvial. NTI Sample #5.
14.1-14.5                     C       dark brown to brown (7.5YR4/2-4/4; moist) loamy sand to sandy loam with
                                      few pebbles; weak medium bedding; very friable; strong effervescence;
                                      unknown lower boundary; subangular 1.0”x1.25”x1.0” black basalt pebble,
                                      fluvial. NTI Sample #6.
16.6-17.0                     C       dark yellowish brown to brown to dark brown (10YR-7.5YR4/4) loamy
                                      sand with few pebbles; very weak thin to medium bedding; very friable;
                                      strong effervescence; unknown lower boundary; subangular
                                      0.75”x1.0”x0.5” white chert pebble; subangular 0.75”x1.0”x0.5” black
                                      basalt pebble, fluvial. NTI Sample #7.
19.1-19.5                     C       brown to dark brown (7.5YR4/4) fine loamy sand with fine to medium
                                      pebbles; very weak medium bedding to massive; very friable to loose;
                                      slight effervescence; unknown lower boundary; single thin medium sand
                                      lens, fluvial. NTI Sample #8.
21.6-22.0                     C       brown to dark brown (7.5YR4/4; saturated) fine loamy sand with medium
                                      pebbles; very weak medium bedding to massive; very friable to loose;
Depth       Horizon
(feet)      or Zone   Description
                      slight effervescence; unknown lower boundary; triangular shaped
                      subangular 1.25”x1.0”x0.5” black basalt pebble, fluvial. NTI Sample #9.
24.1-24.5       C     dark yellowish brown to brown to dark brown (10YR-7.5YR4/4)
                      alternating fine sandy loam with pebbles and very fine to fine sand; very
                      weak bedding to massive (sandy loam) and single grain (fine sands); very
                      friable (loams) and loose (sands); slight effervescence; unknown lower
                      boundary; abrupt boundaries between intra-sample beds, fluvial. NTI
                      Sample #10.
26.6-27.0       C     brown (7.5YR5/4; saturated) silty clay loam to sandy clay loam with
                      medium pebbles; massive; firm; slight effervescence; unknown lower
                      boundary; chert and metamorphic pebbles are subrounded; sedimentary
                      pebbles are subangular, fluvial/alluvial. NTI Sample #11.
29.1-29.5       C     brown (7.5YR5/4; saturated) sandy clay loam diamicton; few very coarse
                      prominent gray to grayish brown (2.5Y5/0-5/2) mottles; massive; very firm;
                      slight effervescence; unknown lower boundary; subrounded fine to medium
                      pebbles with long axis dipping 45-50 degrees (fabric orientation could not
                      be determined from uncontrolled split-spoon sampler), till. NTI Sample
                      #12.
31.6-32.0       C     uppermost 0.25 inches are same as above except for abrupt gravelly lag
                      deposit to 31.7 feet at lower boundary; very thin iron oxidized sand bed
                      under lag deposit; 31.7-32.0 feet is strong brown to reddish yellow
                      (7.5YR5/4-6/8) coarse to very coarse sand with crumbling pebbles; single
                      grain; loose; slight effervescence; unknown lower boundary, till over lag
                      over fluvial. NTI Sample #13.
34.1-34.5       C     brownish yellow (10YR6/8) medium to coarse sand with common pebbles;
                      single grain; loose; slight effervescence; unknown lower boundary; pebbles
                      and coarse sands are well rounded to subangular, fluvial. NTI Sample #14.
36.6-37.0       C     brownish yellow (10YR6/8) fine to medium sand; single grain; loose; slight
                      effervescence; unknown lower boundary; single fine flat crumbling black
                      schist pebble (aerodynamic shape may explain this being the only pebble
                      amongst the finer sand grains), fluvial. NTI Sample #15.
39.1-39.5       C     yellowish brown (10YR5/4; saturated) very coarse sand to loamy sand;
                      common medium distinct very dark brown (10YR2/2) and reddish yellow
                      (7.5YR6/8) mottles; single grain; very friable to loose; slightly sticky in
                      localized spots; slight effervescence; unknown lower boundary; variety of
                      mottles indicates that a textural/hydraulic boundary may be in close
                      proximity, fluvial. NTI Sample #16.
39.5-43.0             drillers reported drilling through granite boulder, possible lag deposit.
44.7-45.0       C     brownish yellow (10YR6/8) sandy clay loam diamicton; many coarse
                      prominent yellowish red (5YR4/6 & 5/8) and very dark gray (10YR3/1)
                      mottles (darker mottles are MnOx staining); alternating wavy and irregular
                      bedding; firm; strong effervescence; unknown lower boundary; subrounded
                      1.0”x1.0”x0.5” black metamorphic pebble; mottle banding within texturally
                      distinct bedding, till. NTI Sample #17.
46.6-47.0       C     brown to light yellowish brown (10YR5/3-6/4) coarse silt loam; common
                      medium distinct reddish yellow (7.5YR6/8) and light gray (2.5Y7/0)
                      mottles; massive; friable; slight effervescence; unknown lower boundary;
                      possible loess or alluvially/colluvially reworked loess. NTI Sample #18.
49.1-49.5       C     very dark grayish brown to dark grayish brown (2.5Y3/2-4/2) clay loam
                      diamicton; massive; extremely firm; slight effervescence; unknown lower
                      boundary, till. NTI Sample #19.
50.5-50.9       C     strong brown (7.5YR5/6) sandy clay loam diamicton; common fine
                      prominent black (10YR2/1) mottles (MnOx staining along joints); massive
                      with traces of fabric; very firm; strong effervescence; unknown lower
Depth                Horizon
(feet)               or Zone    Description
                                boundary. Drillers reported lithologic change at 51.7 ft., till. NTI Sample
                                #20A
51.8-52.0                C      grayish brown (2.5Y5/2) fine sand; single grain; loose; noneffervescent;
                                abrupt lower boundary, alluvium. NTI Sample #20B
54.1-54.5                C      light brownish gray (2.5Y6/2-6/4) silt loam; many medium distinct strong
                                brown (7.5YR5/8) mottles; weak thin bedding; friable; strong
                                effervescence; unknown lower boundary, alluvium/colluvium. NTI Sample
                                #21.
56.6-57.0                C      uppermost 0.04 feet is a light brownish gray (10YR-2.5Y6/2) fine silt loam;
                                few fine prominent reddish yellow (7.5YR6/8) mottles; massive; friable to
                                firm; slight effervescence; abrupt lower boundary; lowermost 0.3 feet is a
                                light brownish gray (10YR-2.5Y6/2) very fine sand; few medium faint
                                brownish yellow (10YR6/6) mottles; very weak bedding to massive; very
                                friable; spotty effervescence; unknown lower boundary, alluvial. NTI
                                Sample #22.
59.1-59.5                C      olive brown (2.5Y4/4; saturated) fine to coarse sand; few fine distinct
                                strong brown (7.5YR5/6) mottles; single grain; loose; slight effervescence;
                                poorly sorted sands indicates probable flood deposit, fluvial. NTI Sample
                                #23.
60.2-60.5                CR     multicolored and alternating silt loams (2.5Y6/0-6/2; possibly weathered
                                shale), silty clay loams (10YR5/4), and sandy clay loams (7.5YR6/8);
                                common prominent black (10YR2/1) MnOx stains; thin bedding; silt loams
                                are hard or weakly cemented and have slight effervescence; silty clay loams
                                are very firm and have strong effervescence; sandy clay loams are firm and
                                have strong effervescence; boundaries within sample are irregular;
                                unknown lower boundary; subrounded 1.75”x1.0”x0.75” pebble at lower
                                boundary, fluvially reworked bedrock. NTI Sample #24.
60.5-61.0              RC & R   brown (10YR5/3) very coarse sands; single grain; loose; violent
                                effervescence; unknown lower boundary; very poor recovery; sand grains
                                are angular and probably represent locally reworked sedimentary bedrock
                                lying on top of shale bedrock; bedrock shale beds reported by drillers at
                                60.5 feet. NTI Sample #25.
End of Split-Spoon              top of bedrock elevation is 897.71 ft.
Boring @ 61.0
                                                                                            LOG OF BORING 13-60260-800
                                      Project Name        : Lillydale Slide
                                      Summit Project No. : 2198-0001
                                                                                             Date              : 7/2/13
                                      Project Location    : Lillydale, MN                    Company/Method : Northern Technologies Inc.
                                      County              : Ramsey                           Sample Method : Wire line Core
      Summit Envirosolutions, Inc.                                                           Field Observer(s) : Ryan Benson
    1217 Bandana Boulevard North      Description Performed by: Brian Gulbranson
                                                         :
                                                                                             Weather           :
       St. Paul, MN 55180-5114        Surface grade elelvation:   N/A


   Depth                                                 MAJOR LITHOLOGY                                       MINOR LITHOLOGY
     in           GRAPHIC LOG                             DESCRIPTIONS                                           DESCRIPTIONS
    feet


                                     Decorah limestone, gray green, argillaceous, fossiliferous
                                     (bryozoans, brachiopods, ostracods, crinoids), extensively
                                     bioturbated (flattened burrows), yellow brown ooids, trace FeS     Calcareous shale, green gray, thin,
                                     fossil replacement, trace black phosphatic grains, rare gypsum     slightly wavy partings
                                     nodules along bedding planes, thin bryozoan coquina beds




                                                                                                        Subvertical fracture, 61.1 - 63.75




                                                                                                        Subvertical fracture, 64.4 - 64.75

  65



                                     No sample



                                     Calcareous Decorah shale, gray green, thinly bedded, clay
                                     particles parallel bedding, rare fossils                           Argillaceous Limestone




                                                                                                        Argillaceous Limestone, 67.4 - 68




  70




                                     Calcareous Decorah shale, gray green, massive, rare fossils




End of Boring at 100 feet.
                                                                                                                      Page 1 of 4
                                                                                           LOG OF BORING 13-60260-800
                                      Project Name        : Lillydale Slide
                                      Summit Project No. : 2198-0001
                                                                                            Date              : 7/2/13
                                      Project Location    : Lillydale, MN                   Company/Method : Northern Technologies Inc.
                                      County              : Ramsey                          Sample Method : Wire line Core
      Summit Envirosolutions, Inc.                                                          Field Observer(s) : Ryan Benson
    1217 Bandana Boulevard North      Description Performed by: Brian Gulbranson
                                                         :
                                                                                            Weather           :
       St. Paul, MN 55180-5114        Surface grade elelvation:   N/A


   Depth                                                 MAJOR LITHOLOGY                                      MINOR LITHOLOGY
     in           GRAPHIC LOG                             DESCRIPTIONS                                          DESCRIPTIONS
    feet




                                     Decorah limestone as above with numerous shale laminae




  75
                                                                                                       Shale, 75 - 75.6




                                     Calcareous Decorah shale, gray green, thinly bedded, clay
                                     particles parallel bedding, rare fossils

                                                                                                       Limestone, 76.7 - 76.75




                                                                                                       Limestone, 79.1 - 79.2


                                                                                                       Limestone, 79.6 - 79.7
                                                                                                       Limestone, 79.8 - 79.85
  80




                                                                                                       Shaly Limestone, 81.1 - 81.65




                                                                                                       Limestone, 82 - 82.2


End of Boring at 100 feet.
                                                                                                                     Page 2 of 4
                                                                                             LOG OF BORING 13-60260-800
                                      Project Name        : Lillydale Slide
                                      Summit Project No. : 2198-0001
                                                                                             Date              : 7/2/13
                                      Project Location    : Lillydale, MN                    Company/Method : Northern Technologies Inc.
                                      County              : Ramsey                           Sample Method : Wire line Core
      Summit Envirosolutions, Inc.                                                           Field Observer(s) : Ryan Benson
    1217 Bandana Boulevard North      Description Performed by: Brian Gulbranson
                                                         :
                                                                                             Weather           :
       St. Paul, MN 55180-5114        Surface grade elelvation:   N/A


   Depth                                                 MAJOR LITHOLOGY                                        MINOR LITHOLOGY
     in           GRAPHIC LOG                             DESCRIPTIONS                                            DESCRIPTIONS
    feet




  85                                 Decorah limestone, blue gray, coarsely crystalline, massive,        Coquina, 84.9 - 85
                                     fossiliferous, trace black phosphatic grains, rare gypsum nodules
                                                                                                         Shale, 85.2 - 85.35
                                                                                                         Coquina, 85.4 - 85.7


                                                                                                         Coquina, 86 - 86.1


                                                                                                         Coquina, 86.6 - 86.7


                                                                                                         Coquina, 87.2 - 87.4
                                                                                                         Shale, 87.5 - 88


                                                                                                         Coquina, 88.1 - 88.6




                                                                                                         Shale, 89.15 - 89.25



  90
                                     No sample




                                     K - Bentonite




End of Boring at 100 feet.
                                                                                                                       Page 3 of 4
                                                                                                LOG OF BORING 13-60260-800
                                      Project Name         : Lillydale Slide
                                      Summit Project No. : 2198-0001
                                                                                                Date              : 7/2/13
                                      Project Location     : Lillydale, MN                      Company/Method : Northern Technologies Inc.
                                      County               : Ramsey                             Sample Method : Wire line Core
      Summit Envirosolutions, Inc.                                                              Field Observer(s) : Ryan Benson
    1217 Bandana Boulevard North      Description Performed by: Brian Gulbranson
                                                         :
                                                                                                Weather           :
       St. Paul, MN 55180-5114        Surface grade elelvation:     N/A


   Depth                                                  MAJOR LITHOLOGY                                         MINOR LITHOLOGY
     in           GRAPHIC LOG                              DESCRIPTIONS                                             DESCRIPTIONS
    feet


                                     Coquina: calcitic, fossiliferous hash of bryozoans, brachiopods,
                                     ostracods and crinoids, includes shaley matrix




                                     Calcareous Decorah shale, gray green, thinly bedded, clay
                                     particles parallel bedding, rare fossils, some detrital fragments



                                     Decorah limestone, blue gray, coarsely crystalline, massive,
  95                                 fossiliferous, trace black phosphatic grains, rare gypsum nodules

                                     Calcareous Decorah shale, gray green, massive, rare fossils

                                                                                                           Limestone, 95.6 - 95.8

                                                                                                           Limestone, 96 - 96.2




                                                                                                           Limestone, 97.4 - 97.6


                                                                                                           Limestone, 98 - 98.25




                                                                                                           Limestone, 98.85 - 98.9


                                                                                                           Limestone, 99.45 - 99.75

100




End of Boring at 100 feet.
                                                                                                                        Page 4 of 4
APPENDIX C
APPENDIX D
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                                                                  0   0.275   0.55   1.1                                         508
                                                                                       Kilometers
                                                             

Photo 1 - 12-inch inlet pipe upstream of 60-inch culvert.
                                                                          

Photo 2 - Energy dissipater and 27-inch pipe upstream from 60-inch culvert.
Photo 3 - Inlet to 60-inch culvert. Note 12-inch pipe connected directly to 60-inch apron.
Photo 4 - Outlet of existing 60 inch diameter concrete culvert. Note channel and bank erosion.
Photo 5 - Bulk headed pipe from Cherokee Heights Blvd. adjacent to outlet of 60-inch culvert
Photograph 6 - Bank erosion near middle of ravine.
Photo 7 - Culvert of unknown origin near middle of ravine. Note
                          blockage.
Photo 8 - Upper waterfall above East Clay Pit.
Photo 9 - Waterfall at East Clay Pit (as viewed from above). The origin of this pipe is unknown.
Photo 10 - Small waterfall present on the southeastern portion of the "horseshoe shaped" bluff
                                     area near failed slope.
Photo 11 - View of failed slope (from above and taken from waterfall area). Note the freshly
cleaved face in the overburden sands on the left section of the bluff wall. The resulting debris
                pile from the slide is located in the bottom center of the image.
Photo 12 - Close view of the slide area. Note the lack of surficial root zone in new scarp as
                compared to ancient scarp on the right side of the image.
Photo 13 - Close view of the newly formed scarp within the slide area (as viewed from below).
APPENDIX E
                                                                                                                                                                                                                    
                                                                                      Direct Shear Test
                                                             ASTM: D3080
                                                                                                                                                                              Job No.:                             9014
    Project/Client: Lilydale Slide / Northern Technologies, Inc.
    Boring No.:HA 1               Sample No.                 Depth: 4-5                                                                                                         Test Date:                         7/10/2013
    Location:                                                       Sample Type: Bag                                                                                        Date Reported:                         7/29/2013
    Soil Type:      Sand with Silt and gravel, fine to medium grained (SP-SM/SM)                                                                                                                      Shear Rate
                                                                                                                                                                                                0.003 (in/min)
    Remarks:      Specimens compacted to given densities, using -#10 material in loose condition; Inundated after                                                                                                              
    applying normal load. Consolidated and sheared to given displacements at constant rate of 0.003 inches/minute.                                                                                                             
                                                                                                                                                                                                   Liquid Limit:
                                                                                                                                                                                                                               
                                                                                                                                                                                                Plastic Limit:                 
 
                                                                                                                                                                                           Plasticity Index:                   
                                                                                                                         (*) = Assumed Specific Gravity                           Specific Gravity (*):                       2.68
                                                                                                                                                                     
                                                                                                                              
                                        0                                                                                                                            
                                                                                                                             Failure Criterion:                      
                                                                                                                                     Max Stress                         A                      B              C                    D
                                  -0.005                                                                                             Initial                                                                                         X
                                                                                                                                 Diameter (In.)                    2.50                       2.50           2.50
                                                                                                                                 Thickness (In.)                   0.92                       0.92           0.92
                                   -0.01
     Change in Thickness (inch)




                                                                                                                          Water Content (%)                         5.7                       5.7            5.7
 
                                                                                                                             Dry Density (pcf)                     107.9                   107.9            107.9
                                                                                                                                 Before Shear
                                  -0.015
                                                                                                                                 Thickness (In.)                   0.91                       0.91          0.89
                                                                                                                          Water Content (%)                        20.2                       19.6          18.8
                                   -0.02                                                                                     Dry Density (pcf)                     108.6                   109.7            111.3
 
                                                                                                                                 Normal Stress                     0.50                       1.00           2.00
                                  -0.025                                                                        Shear Stress             0.34            0.71        1.31
                                                                                                         "These tests are for informational purposes only and must be reviewed by a
                                                                                                         qualified professional engineer to verify that the test parameters shown are
                                   -0.03                                                                 appropriate for any particular design."
                                                                                                                                                                                                                                              
                                                                                                                                               Peak Conditions                            At Given Shear Disp. Of:                           0.2
                                  -0.035                                                                                 Friction Angle:                φ=     32.7 deg.                  Friction Angle:              φ=     32.7 deg.
                                            0    0.05             0.1          0.15      0.2                                     Apparent
                                                                                                                                                                
                                                                                                                                                                                              Apparent
                                                                                                                                                                                                                                          
                                                                                                                                                               0.037 TSF                                                0.036            TSF
                                                                                                                             Cohesion                                                         Cohesion
                                  1.4                                                                                         
                                                                                                                             2
 
                                                                                                                      
                                  1.2
                                                                                                                     1.75
 
 
                                    1                                                                                    1.5
 
                                                                                                Shear Stress (TSF)




 
 
       Shear Stress (TSF)




                                                                                                                     1.25
                                  0.8
 
                                                                                                                                 1
                                  0.6
 
                                                                                                                     0.75
 
                                  0.4                                                                                     
                                                                                                                         0.5
 
 
                                                                                                                      
                                  0.2                                                                                0.25
 
 
                                    0                                                                                        0
                                        0       0.05             0.1           0.15       0.2                                         0         0.25     0.5       0.75               1            1.25     1.5             1.75             2
                                                                                                                              
                                                       Shear Displacement (inch)                                                                                   Normal Stress (TSF)
 



                                                                                                     Grain Size Distribution ASTM D422                                                                                        Job No. :          9014
            Project:                           Lilydale Slide                                                                                                                                                                Test Date:          7/10/13
        Reported To:                           Northern Technologies, Inc.                                                                                                                                                 Report Date:          7/10/13
                                                                                                                Sample
                                     Location / Boring No.                    Sample No.             Depth (ft) Type                                                                      Soil Classification
                                                                                                                     
         *                               Side of Debris Pile                                                             Bag                                                   Silty Sand w/a little gravel (SM)
                                                                                                                     
                                              HA 1                                                      4-5              Bag                                                 Sand w/silt and gravel (SP-SM/SM)
                                                                                                                                  
     
                                                         Gravel                                                                Sand                                                                         Hydrometer Analysis
                                              Coarse                          Fine               Coarse                  Medium                            Fine                                                   Fines
                                               2         1      3/4               3/8       #4            #10                  #20          #40                 #100         #200
             100
     
     
                       90
     
     
                       80
     
     
                       70
     
     
                       60
     
         Percent Passing




     
                       50
     
     
                       40
     
     
                       30
     
     
                       20
     
     
                       10
     
     
                            0
                                              50               20                           5                 2                          .5                .2                       .05               .02                      .005       .002
                                100                                               10                                         1          Grain Size (mm)                0.1                                          0.01                           0.001
     
                                                                    Other Tests                                                        Percent Passing
     
                                                        *                                                                        *                                                                      *                   
                           Liquid Limit                                                                Mass (g)                982.0          1039.9                                      D60                               
                      Plastic Limit                                                                                 2"                                                                    D30                               
             Plasticity Index                                                                                     1.5"                                                                    D10                               
             Water Content                             7.5                  5.8                                     1"                         100.0                                      CU                                
         Dry Density (pcf)                                                                                        3/4"         100.0           91.6                                       CC                                
         Specific Gravity                                                                                     3/8"             98.5            87.2                                 Remarks:

     
                             Porosity                                                                              #4          95.5            80.1     
     
         Organic Content                                                                                          #10          78.8            69.6     
     
                                    pH                                                                            #20          65.6            59.8     
     
          Shrinkage Limit                                                                                         #40          50.6            44.7     
     
                 Penetrometer                                                                                 #100             27.3            15.9     
                             Qu (psf)                                                                         #200             20.0            11.6     
               (* = assumed)

     
     
                                                   2401 W 66th Street                                                                                                                            Richfield, Minnesota 55423-2031



 
                                                                                  Direct Shear Test
                                                         ASTM: D3080
                                                                                                                                                         Job No.:                      9014
Project/Client: Lilydale Slide / Northern Technologies, Inc.
Sample No.            Slide Debris Pile                  Depth:                                                                                           Test Date:                 7/10/2013
Location:                                                       Sample Type: Bag                                                                      Date Reported:                 7/29/2013
Soil Type:      Silty Sand with a little gravel (SM)                                                                                                                    Shear Rate
                                                                                                                                                                   0.003 (in/min)
Remarks:      Specimens compacted to given densities, using -#10 material in loose condition; Inundated after
applying normal load. Consolidated and sheared to given displacements at constant rate of 0.003 inches/minute.
                                                                                                                                                                   Liquid Limit:
                                                                                                                                                                  Plastic Limit:
                                                                                                                                                               Plasticity Index:
                                                                                                                 (*) = Assumed Specific Gravity            Specific Gravity (*):            2.68

                                    0
                                                                                                                   Failure Criterion:
                                                                                                                        Max Stress                A               B              C             D
                              -0.005                                                                                    Initial                                                                X
                                                                                                                    Diameter (In.)               2.50           2.50         2.50
                                                                                                                    Thickness (In.)              0.92           0.92         0.92
                               -0.01
 Change in Thickness (inch)




                                                                                                                  Water Content (%)               7.5            7.5             7.5
                                                                                                                   Dry Density (pcf)             108.3          108.3        108.3
                                                                                                                    Before Shear
                              -0.015
                                                                                                                    Thickness (In.)              0.91           0.90         0.90
                                                                                                                  Water Content (%)              19.6           19.3         18.9
                               -0.02                                                                               Dry Density (pcf)             109.8          110.3        111.0


                                                                                                                    Normal Stress                0.50           1.00         2.00
                              -0.025                                                                        Shear Stress             0.40           0.74         1.46
                                                                                                     "These tests are for informational purposes only and must be reviewed by a
                                                                                                     qualified professional engineer to verify that the test parameters shown are
                               -0.03                                                                 appropriate for any particular design."

                                                                                                                              Peak Conditions                  At Given Shear Disp. Of:            0.2
                              -0.035                                                                             Friction Angle:         φ= 35.2 deg.          Friction Angle:         φ=   35.1 deg.
                                        0    0.05             0.1          0.15       0.2                           Apparent                                     Apparent
                                                                                                                                               0.046 TSF                               0.046       TSF
                                                                                                                   Cohesion                                      Cohesion
                              1.6
                                                                                                                   2

                              1.4
                                                                                                                 1.75

                              1.2
                                                                                                                  1.5
                                                                                            Shear Stress (TSF)




                                1
   Shear Stress (TSF)




                                                                                                                 1.25


                              0.8
                                                                                                                   1


                              0.6                                                                                0.75


                              0.4                                                                                 0.5


                              0.2                                                                                0.25



                                0                                                                                  0
                                    0       0.05             0.1           0.15       0.2                               0         0.25   0.5      0.75     1          1.25   1.5        1.75       2
                                                   Shear Displacement (inch)                                                                     Normal Stress (TSF)
                                           Laboratory Test Summary
      Project:                                         Lilydale Slide                Job:    9014
      Client:                                   Northern Technologies, Inc.          Date: 7/31/2013


                                              Sample Information & Classification

     Boring #

     Sample #

     Depth (ft)           71         80

   Type or BPF           Bag         Bag


     Material          Lean Clay   Fat Clay
   Classification        (CL)       (CH)




                                              Moisture Contents & Atterberg Limits

Moisture Content (%)     16.3       13.8


 Liquid Limit (%)        43.0       52.4

 Plastic Limit (%)       16.4       18.6

Plasticity Index (%)     26.6       33.8


                                              Sample Information & Classification

     Boring #

     Sample #

     Depth (ft)

   Type or BPF


     Material
   Classification




                                              Moisture Contents & Atterberg Limits

Moisture Content (%)


 Liquid Limit (%)

 Plastic Limit (%)
Plasticity Index (%)
                                                                                        Torsional Ring Shear Test
                                                                                                          ASTM D:6467-06a                                                                                              Job #:       9014
                          Project: Lilydale Slide                                                                                              Client: Northern Technologies, Inc.                                      Date:       7/29/2013
                          Boring:                                                                        Sample:                                                                                       Depth:                  71
                     Location:
            Soil Type:                                                                                          Lean Clay (CL)
              Remarks:                           Testing performed in general accordance with ASTM:D6467-06a. The testing chamber was modified to minimize sidewall friction.
The specimen was air dried and ground through a #200 sieve. The specimen was the rehydrated past the liquid limit and allowed to adjust for at least 10 days. The specimen was then placed into the testing
chamber with a spatula. The sample was incrementally consolidated to 7.7 tsf and then unloaded to the initial testing pressure and presheared a minimum of 1 full rotation. The testing chamber was then removed
from the apparatus and the wall height adjusted to specimen height minimizing sidewall friction. The testing chamber was then placed into the appatarus and sheared at the given rate until a constant load was
measured. The specimen was then loaded to the next normal pressure and sheared again. This was repeated for a 3rd pressure before completing the test.

 Shear Rate:                                0.0270   °/min                Initial Ht:   0.197 in    Outer Dia.:    3.937 in                                    Inner Dia.:     2.756 in                       Atterberg Limits
                                                                                    Consolidated Specimen Info                                                                                                            LL:          43.0
Normal                                       1.50 tsf                         2.25 tsf                     3.00 tsf                                                            tsf                                        PL:          16.4
Height                                            in                               in                           in                                                             in                                         PI:          26.6
Residual                                     0.57 tsf                         0.83 tsf                     1.10 tsf                                                            tsf                      Clay Fraction (%):
Secant                                       20.7 °                           20.3 °                       20.1 °                                                              °                   Organic Content (%):

                                                            Secant Angles                                                                                                              Strength Envelope
                          5                                                                                                                    5


                                                                                                                                                                                                       ɸ =19.4°        c =0.04 TSF

                          4                                                                                                                    4




                                                                                                                    Shear Stress TSF
  Shear Stress TSF




                          3                                                                                                                    3




                          2                                                                                                                    2




                          1                                                                                                                    1




                          0                                                                                                                    0
                              0              1                2                3              4             5                                      0                   1                 2                3                4                  5
                                                              Normal Stress                                                                                                              Normal Stress

                                             Shear Stress vs Angle of Rotation                                                                                         Change in Thickness vs Angle of Rotation
                          1.2                                                                                                                  0.012



                                                                                                                                                   0.01
                              1
                                                                                                                    Change in Thickness (in)




                                                                                                                                               0.008
                          0.8
       Shear Stress tsf




                                                                                                                                               0.006

                          0.6

                                                                                                                                               0.004


                          0.4
                                                                                                                                               0.002



                          0.2
                                                                                                                                                       0



                              0                                                                                                                -0.002
                                  0   0.5     1       1.5      2    2.5        3        3.5   4    4.5      5                                              0     0.5       1     1.5         2   2.5      3      3.5      4      4.5      5
                                                             Degrees Rotation                                                                                                           Degrees Rotation
                                                                                        Torsional Ring Shear Test
                                                                                                          ASTM D:6467-06a                                                                                               Job #:      9014
                          Project: Lilydale Slide                                                                                              Client: Northern Technologies, Inc.                                      Date:       7/24/2013
                          Boring:                                                                        Sample:                                                                                       Depth:                  80
                     Location:
            Soil Type:                                                                                          Fat Clay (CH)
              Remarks:                           Testing performed in general accordance with ASTM:D6467-06a. The testing chamber was modified to minimize sidewall friction.
The specimen was air dried and ground through a #200 sieve. The specimen was the rehydrated past the liquid limit and allowed to adjust for at least 10 days. The specimen was then placed into the testing
chamber with a spatula. The sample was incrementally consolidated to 7.7 tsf and then unloaded to the initial testing pressure and presheared a minimum of 1 full rotation. The testing chamber was then removed
from the apparatus and the wall height adjusted to specimen height minimizing sidewall friction. The testing chamber was then placed into the appatarus and sheared at the given rate until a constant load was
measured. The specimen was then loaded to the next normal pressure and sheared again. This was repeated for a 3rd pressure before completing the test.

 Shear Rate:                                0.0270   °/min                Initial Ht:   0.197 in    Outer Dia.:    3.937 in                                    Inner Dia.:     2.756 in                       Atterberg Limits
                                                                                    Consolidated Specimen Info                                                                                                             LL:          52.4
Normal                                       1.50 tsf                         2.25 tsf                     3.00 tsf                                                            tsf                                         PL:          18.6
Height                                            in                               in                           in                                                             in                                          PI:          33.8
Residual                                     0.46 tsf                         0.68 tsf                     0.90 tsf                                                            tsf                      Clay Fraction (%):
Secant                                       17.3 °                           16.8 °                       16.7 °                                                              °                   Organic Content (%):

                                                            Secant Angles                                                                                                              Strength Envelope
                          5                                                                                                                    5

                                                                                                                                                                                                                ɸ =16.1°       c =0.03
                                                                                                                                                                                                                TSF
                          4                                                                                                                    4




                                                                                                                    Shear Stress TSF
  Shear Stress TSF




                          3                                                                                                                    3




                          2                                                                                                                    2




                          1                                                                                                                    1




                          0                                                                                                                    0
                              0              1                2                3              4             5                                      0                   1                 2                3                4                   5
                                                              Normal Stress                                                                                                              Normal Stress

                                             Shear Stress vs Angle of Rotation                                                                                         Change in Thickness vs Angle of Rotation
                              1                                                                                                                    0.01


                          0.9
                                                                                                                                               0.008
                          0.8
                                                                                                                    Change in Thickness (in)




                          0.7                                                                                                                  0.006
       Shear Stress tsf




                          0.6
                                                                                                                                               0.004

                          0.5

                                                                                                                                               0.002
                          0.4


                          0.3                                                                                                                          0

                          0.2
                                                                                                                                               -0.002
                          0.1


                              0                                                                                                                -0.004
                                  0   0.5     1       1.5      2    2.5        3        3.5   4    4.5      5                                              0     0.5       1     1.5         2   2.5      3       3.5      4      4.5      5
                                                             Degrees Rotation                                                                                                           Degrees Rotation
APPENDIX F
                                          Bibliography

Emerson, W. W., 1967, Coherence of clay crystals in water: (Abst.) Clays and Clay Minerals, p.
255.

Kolata, D.R., Frost, J.K., Huff, W.D., 1986, K-bentonites of the Ordovician Decorah Subgroup,
Upper Mississippi Valley: Correlation by chemical fingerprinting: Illinois State Geological Survey
Circular 537.

Levorson, C.O., Gerk, A.J., Sloan, R.E., and Bisagno, L.A., General Section of the Middle and
Late Ordovician strata of Northeastern Iowa, in Sloan, R.E., ed., Middle and Late Ordovician
lithostratigraphy and biostratigraphy of the upper Mississippi valley: Minnesota Geological Survey
Report of Investigations 35, p.25 – 39.

Mossler, J. H., 2008, Paleozoic Stratigraphic Nomenclature for Minnesota: Minnesota Geological
Survey Report of Investigations 65.

Mossler, J. H., and Hayes, J.B., 1966, Ordovician potassium bentonites of Iowa: Journal of
Sedimentary Petrology, v. 36, p. 414 – 427.

Ojakangas, R. W., and Matsch, C. L., 1982, Minnesota’s Geology, Minneapolis, University of
Minnesota Press, p. 75 – 79.

Parham, W. E., 1966, Lateral variations of clay mineral assemblages in modern and ancient
sediments: International Clay Conf. Proc., v. 1, p. 135 – 145.

Parham, W. E., and Austin, G. S., 1969, Clay mineralogy and industrial uses of the shale of the
Decorah Formation, Southeastern Minnesota: Minnesota Geological Survey Report of
Investigations 10.

Pettijohn, F.J., 1975, Sedimentary Rocks (3rd Edition): New York, Harper & Row, 628 p.

Rice, W. F., 1987, The systematic and biostratigraphy of the brachiopoda of the Decorah Shale at
St. Paul, Minnesota, in Sloan, R.E., ed., Middle and Late Ordovician lithostratigraphy and
biostratigraphy of the upper Mississippi valley: Minnesota Geological Survey Report of
Investigations 35, p.136 - 166.

Sloan, R. E., 1987, Tectonics, biostratigraphy and lithostratigraphy of the Middle and Late
Ordovician of the upper Mississippi valley: in Sloan, R.E., ed., Middle and Late Ordovician
lithostratigraphy and biostratigraphy of the upper Mississippi valley: Minnesota Geological Survey
Report of Investigations 35, p.7 -20.

				
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