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					The Potential Impacts of Limited
  Gravel Extraction on the Lake
   Pleasant Basin, Pennsylvania

                                          Final Draft


                                                     Prepared by:
                                   DAVID S. MILLER, PH.D.
                            GUSTAVIOUS P. WILLIAMS, PH.D.
                  GEOLOGICAL SCIENCE AND INFORMATION TECHNOLOGY
                              ENVIRONMENTAL ASSESSMENT DIVISION
                                   ARGONNE NATIONAL LABORATORY




                                                    Prepared for:
               THE WESTERN PENNSYLVANIA CONSERVANCY




         January 14, 2000
JANUARY 13, 2000                                                   FINAL DRAFT                                 LAKE PLEASANT IMPACT STUDY




Table of Contents

Introduction ...................................................................................................................................... 1

Hydrogeologic Setting ...................................................................................................................... 3

Geology ............................................................................................................................................ 3

Groundwater Drainage and Geochemistry ........................................................................................ 4

Site Visit and Observations............................................................................................................... 6
        Gravel Mine Southwest of Lake Pleasant ............................................................................ 6
        Northern Gravel Mine Extension ......................................................................................... 7

Conclusions ...................................................................................................................................... 9
       Southwestern Mining Area .................................................................................................. 9
       Northern Mining Area ......................................................................................................... 9

Recommendations........................................................................................................................... 10
      Southwestern Gravel Mine ................................................................................................ 10
      Northern Gravel Mine........................................................................................................ 10

References ...................................................................................................................................... 12

Appendix A .................................................................................................................................... 13




ENVIRONMENTAL ASSESSMENT DIVISION                                        ii                                ARGONNE NATIONAL LABORATORY
JANUARY 13, 2000                                                 FINAL DRAFT                                LAKE PLEASANT IMPACT STUDY




List of Figures
Figure 1 Lake Pleasant watershed looking east from a hill overlooking the southern end of the
       lake. The lake outlet and some of the southern wetland area can be seen. ........................... 2

Figure 2 Bank cut in the till northwest of Lake Pleasant showing cobbles, gravel, and sand
       deposits. ............................................................................................................................... 3

Figure 3 An example of lithified glacial outwash. ........................................................................... 5

Figure 4 Lithified layer in the glacial outwash in the southern gravel mine west of Lake Pleasant
       wetland. ............................................................................................................................... 5

Figure 5 Existing gravel operations southwest of Lake Pleasant. This is the location of the
       proposed extraction of an additional 30,000 tons of gravel. The southern edge of Lake
       Pleasant can be seen at the left edge of the figure. ............................................................... 6

Figure 6 Existing buffer along the east edge of the southern gravel pit. This buffer separates the
       adjacent wetlands from surface runoff from the gravel mine. .............................................. 6

Figure 7 Northern gravel mine showing active operations. .............................................................. 7

Figure 8 Location of the proposed 100-foot extension to the northern gravel pit. ........................... 7




ENVIRONMENTAL ASSESSMENT DIVISION                                      iii                              ARGONNE NATIONAL LABORATORY
JANUARY 13, 2000                            FINAL DRAFT                    LAKE PLEASANT IMPACT STUDY




 The Potential Impacts of Limited Gravel
  Extraction on the Lake Pleasant Basin,
              Pennsylvania
                                   DAVID S. MILLER, PH.D.
                                GUSTAVIOUS P. WILLIAMS, PH.D.
                           GEOLOGICAL SCIENCE AND INFORMATION TECHNOLOGY
                                ENVIRONMENTAL ASSESSMENT DIVISION
                                   ARGONNE NATIONAL LABORATORY




Introduction
        The Western Pennsylvania Conservancy (WPC) has requested that the Environmental
Assessment Division (EAD) of Argonne National Laboratory provide technical assistance in
evaluating the potential impacts of gravel mining in the Lake Pleasant watershed located in
western Pennsylvania. The lake is in Waterford and Greene Townships of Erie County.

         Lake Pleasant (Figure 1) was formed as the result of Pleistocene glaciation and much of
its original quality remains intact. The quality, flow, and distribution of the water in this
watershed are key contributors to its environmental qualities. Appendix A identifies 24 plant
species and 4 animals of special concern that occur in the Lake Pleasant watershed (Pennsylvania
DEP 1999 and WPC 1999).

        The area around the lake is relatively undeveloped for residential or industrial use, but
extensive gravel mining has occurred in the watershed. Mining has been particularly intensive in
the upgradient, northern areas of the watershed.

        Large-scale gravel mining may have serious potential impacts on a watershed like the
Lake Pleasant watershed. Excavating below the water table exposes groundwater to surface
conditions. Exposing the water to sunlight and the atmosphere may change it biologically and
chemically, and those changes may propagate through and change the watershed. Removal of
large volumes of sand and gravel may also change the flow paths and rates at which water travels
through the watershed.




ENVIRONMENTAL ASSESSMENT DIVISION               1                     ARGONNE NATIONAL LABORATORY
JANUARY 13, 2000                             FINAL DRAFT                   LAKE PLEASANT IMPACT STUDY




         The WPC questions whether the removal of an additional 30,000 tons of gravel from an
active gravel mine southwest of Lake Pleasant (and the associated land disturbance) would be
expected to have significant impacts on the water quality and hydrology of the lake and adjacent
wetlands. A second issue raised by the WPC is whether there would be significant impacts to the
water quality of the lake and wetlands from extending the sidewall of an existing gravel mine north
of Lake Pleasant an additional 100 feet.

        It is important to note that no judgment is made here as to the overall changes that may
have resulted to the historic water quality of the lake and its wetlands from past gravel mining
operations. This study only addresses the potential relative impacts of additional, limited gravel
mining.




Hydrogeologic Setting
        Lake Pleasant, a 64 acre lake, lies within a 6 mi2 watershed in the French Creek drainage,
located south of the Lake Erie plain. French Creek is part of the Ohio River basin.

         The Lake Pleasant watershed occupies a valley approximately two miles wide. The axis
of the valley is oriented generally northwest-southeast, with parallel ridges bounding the valley to
the northeast and southwest. Surface water drains to the southeast. The ridges are formed in rock


ENVIRONMENTAL ASSESSMENT DIVISION                 2                     ARGONNE NATIONAL LABORATORY
JANUARY 13, 2000                             FINAL DRAFT                   LAKE PLEASANT IMPACT STUDY

of the Devonian Venango formation, an interbedded, coarse-grained sandstone and shale
formation (Richards et al. 1987). The bedrock of the valley is composed of the Devonian
Chadokoin formation, an interbedded shale and sandstone that is more easily eroded than the
Venango formation.

Geology
         The valley is filled with sediments deposited by glacial ice and meltwater. Several major
episodes of glaciation and de-glaciation occurred during the Pleistocene epoch. Each major
episode included a number of minor advances and retreats of the glacial front. The Lake Pleasant
vicinity experienced between 5 and 10 advances and retreats of the ice front in the last two major
glaciations: the Illinoian (older) and Wisconsin (younger) glaciations. The two most recent minor
advances and retreats, known as the Kent and Lavery advances, were responsible for the current
valley surface topography and near-surface geologic configurations in the Lake Pleasant valley
(White et al. 1969). The Kent ice advance and retreat occurred between 20,000 and 25,000 years
ago; the Lavery advance and retreat occurred between 15,000 and 20,000 years ago.

         As the glaciers advanced, they carried and pushed clay, silt, sand, cobbles, and boulders
(Figure 2). As they melted and retreated, they left the sediments and rocks behind in deposits
known as glacial till. Till is typically a complex mix of clay, silt, sand, boulders, and cobbles. The
till occurs in thin veneers a few feet thick on the ridges and their flanks. However, toward the axis
of the valley, the till thickens and is estimated to be at least 100 feet thick in the center of the
valley beneath the lake and wetlands (Richards et al. 1987).
         Great amounts of water flowed from the glaciers as they melted. Enormous blocks of ice
broke away and were carried with the meltwater. The meltwater eroded a complex series of
channels through the previously deposited till and also laid down sediments of its own. Meltwater
deposits, known as glacial outwash deposits, are better sorted than till. Relatively well-sorted,
discrete clay, silt, sand, and gravel beds were laid down in the meltwater rivers depending on the
velocity and depth of the water. Clays and silts were deposited in relatively quiet water, while
sand and gravel layers formed where the water moved more rapidly. The gravel deposits of
concern to this study were formed in this manner.

         Because of the multiple advances and retreats of the glaciers, a complex configuration of
till and outwash was deposited in the Lake Pleasant valley. Tills were eroded by meltwater, which
laid down outwash deposits, which were eroded by later glacial advances. Then, the remnants
were covered with till and outwash from the latest glacial advance.

Groundwater Drainage and Geochemistry
          Wellington (1991) noted the absence of surface water sources to Lake Pleasant, a
characteristic feature of geologic settings where the materials have high porosity and permeability.
 Sand and gravel deposits, like those of the Lake Pleasant watershed, allow rainfall and snowmelt
to infiltrate into the ground rather than run off to streams. The result is that virtually all of the
water flowing to Lake Pleasant and its wetlands from the farthest reaches of its watershed travels
along subsurface pathways, where it chemically interacts with the subsurface materials.


ENVIRONMENTAL ASSESSMENT DIVISION                 3                     ARGONNE NATIONAL LABORATORY
JANUARY 13, 2000                            FINAL DRAFT                  LAKE PLEASANT IMPACT STUDY



          Rocks and minerals
from far into Canada to
nearby in Pennsylvania
compose the till and outwash
of the Lake Pleasant valley.
An important aspect of the
till and outwash in the valley
is that they contain
significant fractions of
limestone and dolomite
(carbonate-rich rocks)
(White et al. 1969). During
a field inspection of the
gravel quarry, several
lithified beds of outwash deposits were noted. Lithification occurs when the particles comprising a
sedimentary deposit are bound together by a cementing agent. The observed beds ranged in
thickness from a few centimeters to nearly a meter (Figures 3 and 4). It is presumed that the
lithification is due to carbonate cement since a vigorous reaction was observed upon contact with
dilute hydrochloric acid. The carbonate content of the till and outwash is significant because
virtually all of the water reaching Lake Pleasant and its wetlands must move through the
carbonate-rich till and outwash before entering the lake, thus contributing carbonate-rich
groundwater to the lake and wetlands.

         The carbonate-rich groundwater influences the pH of the lake and wetlands water. The
pH and dissolved oxygen of the water of Lake Pleasant were measured at one meter depth intervals
near the center of the lake in August 1991 (Wellington 1991). Below 6 meters in depth, the pH
ranged from 6.7 to 7.1 and the dissolved oxygen ranged from 0.6 to 1.7 ppm. In the top 6 meters
of the water profile, the pH was very nearly constant between 8.1 and 8.2, except in the 5 to 6
meter interval where the pH was 7.6. The dissolved oxygen ranged between 8.9 and 9.4 ppm in
the top 5 meters of the water profile and was 6.7 ppm between 5 and 6 meters in depth.




ENVIRONMENTAL ASSESSMENT DIVISION               4                     ARGONNE NATIONAL LABORATORY
JANUARY 13, 2000                    FINAL DRAFT     LAKE PLEASANT IMPACT STUDY




ENVIRONMENTAL ASSESSMENT DIVISION       5         ARGONNE NATIONAL LABORATORY
JANUARY 13, 2000                             FINAL DRAFT                    LAKE PLEASANT IMPACT STUDY




Site Visit and Observations

Gravel Mine Southwest of Lake Pleasant
        This gravel mine is located southwest of Lake Pleasant and adjacent to the western edge of
the wetlands south of the lake (Figure 5). It has been proposed to extract an additional 30,000 tons
of gravel from this mine.

          Representatives of EAD and the WPC conducted a field inspection of the Lake Pleasant
gravel mines on December 7 and 8, 1999. The current mine, southwest and down gradient of the
lake, is separated from the wetlands by a vegetated buffer at least 25 feet wide (Figure 6). The
surface of the buffer is at, or very near, the original natural grade and is higher than the bottom of
the gravel pit and adjacent wetland. The buffer provides a barrier to surface flow from the pit to
the adjacent wetlands. Inspection revealed that currently there is no route for surface water to
move from the gravel mine to the wetland, so any water moving from the mine to the wetland
must travel via subsurface flow paths. It is probable that higher rates of groundwater flow occur
through the coarse-grained outwash deposits relative to the finer-grained till. Because the outwash
and till have been deposited in a complex manner, the actual flow paths are expected to be
complicated.

         Because the lithified sediments observed in the mine are cemented with carbonate
minerals, water flowing toward the wetland has, at some point in the past, been saturated with
respect to carbonate. It is unknown whether lithification is currently occurring.

          The pattern of gravel
mined to date showed that
the gravel deposits occur
near the valley floor and
extend in lobate fingers
down-valley and toward the
wetland in the valley axis.
Most of the water moving
through the carbonate rich
till in the upper reaches of
the watershed would
eventually enter the wetland
through one of these
coarse-grained, subsurface
flow paths.



ENVIRONMENTAL ASSESSMENT DIVISION                 6                      ARGONNE NATIONAL LABORATORY
JANUARY 13, 2000                           FINAL DRAFT                  LAKE PLEASANT IMPACT STUDY


Northern Gravel Mine
Extension
         It is proposed to extend the
current sidewall of an existing gravel
mine in the northern part of the
watershed 100 feet toward the lake.
Figure 7 is a photograph of the
existing gravel operation in the
northern part of the watershed.
Figure 8 shows the sidewall where
the proposed 100-foot extension is to
occur.

        This site was also inspected
by EAD and WPC representatives.
The current southern sidewall of this
mine is at least 600 feet from the
wetland north of the lake. It is
approximately 2,000 feet from the northern edge of the lake. The mine is active, and the proposed
extension is located away from the water flow line in the southeastern corner of the mining pit.
The base of the current mine intercepts groundwater. No surface water pathways were noted
leading from this mine to either the wetland or the lake. The proposed mining extension is very
small compared to the size of the active gravel mine.




ENVIRONMENTAL ASSESSMENT DIVISION               7                    ARGONNE NATIONAL LABORATORY
JANUARY 13, 2000                             FINAL DRAFT                    LAKE PLEASANT IMPACT STUDY


Conclusions
Southwestern Mining Area
         Thirty-thousand tons of gravel is a relatively small amount of gravel to be removed
compared to what has already been mined southwest of the lake. Because of the presence of the
raised buffer area that separates the mining operation from the adjacent wetlands, there is little
likelihood that sediments will be carried into the wetland by surface water unless the buffer
adjacent to the gravel mine is breached.

         Each ton of gravel occupies about 2/3 of a cubic yard. If the excavation to remove the
additional 30,000 tons of gravel is 3 feet deep, it would extend over a square area approximately
400 feet on a side. Shallower excavations would affect a larger area. This size of area is
insignificant in relation to the area of the existing mine.

        Care should be taken during continued mining to maintain the integrity of the existing
raised buffer area to eliminate the possibility of surface erosion and transport of sediment to the
wetland. If these precautions are taken, additional impacts from the removal of an additional
30,000 tons are gravel are expected to be slight.

        Minor changes in groundwater flow rates and pathways are likely to occur in the
immediate vicinity of the proposed gravel removal. However, these changes are expected to be
negligible relative to the changes that have occurred as a results of past mining and are not
expected to change current conditions in the areas immediately surrounding the gravel mine.

Northern Mining Area
         The extension of the existing operation in the northern end of the watershed is very small
compared to the extent of the existing mine and is located in a area of the mine away from the
central drainage. The mine is currently active, and even if this extension is not approved, mining
operations will continue in other areas of the pit. The additional impacts to the water quality of
Lake Pleasant resulting from a 100 foot extension of the sidewall in this southeastern corner is
expected to be insignificant.




ENVIRONMENTAL ASSESSMENT DIVISION                 8                      ARGONNE NATIONAL LABORATORY
JANUARY 13, 2000                              FINAL DRAFT                    LAKE PLEASANT IMPACT STUDY


Recommendations
        It is important to re-state that no judgment is made here as to the overall changes that may
have resulted to the historic water quality of the lake and its wetlands from past gravel mining
operations.

        A number of actions related to the limited removal of gravel could cause impacts to the
wetland. The following actions are recommended to protect the wetland:

Southwestern Gravel Mine
         1) Care should be taken to maintain a minimum buffer zone 25 feet wide along the eastern
         and southern edges of the gravel pit at an elevation as close to the original natural grade as
         possible. In no case should the buffer zone be breached so that surface water may escape
         from the gravel pit via an overland flow path that would not have existed prior to the
         inception of the first gravel mining. (In essence, this translates to no surface flow over the
         buffer, even during extreme hydrologic conditions).

         2) Care should be taken to prevent the surface disturbance of the buffer zone, including
         removal of vegetation, dumping, or moving or storing equipment or supplies on the buffer
         zone. If the surface of the buffer zone is disturbed, erosion could result, potentially
         impacting the wetland areas.

         3) Maximizing the width of the buffer wherever possible is recommended.

Northern Gravel Mine
         1) The sidewall slope of the extension in the northern gravel mine should be graded gently
         enough to provide a stable slope face and minimize the formation of rills. Where feasible
         the slope should be graded at 1 ft vertical to 3 ft horizontal (1 to 3 slope). In no case
         should the grade exceed 1 ft vertical to 2 ft horizontal (1 to 2 slope).

         2) The slope should be re-vegetated as soon as is practically possible after the gravel is
         removed.




ENVIRONMENTAL ASSESSMENT DIVISION                  9                      ARGONNE NATIONAL LABORATORY
JANUARY 13, 2000                          FINAL DRAFT                 LAKE PLEASANT IMPACT STUDY


References
Pennsylvania Department of Environmental Protection (1999), http://www.dep.state.pa.us/ -
       dep/deputate/polycomm/update/03-12-99/03129936.htm, accessed December 12, 1999.

Richards, David B., H. Jack McCoy, and John T. Gallaher (1987), Groundwater Resources of Erie
       County, Pennsylvania,Water Resources Report Number 62, prepared by the US
       Geological Survey, Water Resources Division, in cooperation with the Pennsylvania
       Geological Survey, Harrisburg, Pennsylvania.

Wellington, Robert J. (1991), Lake Pleasant Survey, Erie County Department of Health, August
                        28.

WPC (Western Pennsylvania Conservancy) (1999), Pennsylvania Natural Diversity Inventory.

White, George W., Stanley M. Totten, and David L. Gross (1969), Pleistocene Stratigraphy of
       Northwestern Pennsylvania, Bulletin G 55, Pennsylvania Geological Survey, Harrisburg,
       Pennsylvania.




ENVIRONMENTAL ASSESSMENT DIVISION             10                   ARGONNE NATIONAL LABORATORY
JANUARY 13, 2000                       FINAL DRAFT             LAKE PLEASANT IMPACT STUDY


Appendix A
         PENNSYLVANIA NATURAL DIVERSITY INVENTORY
                           Western Pennsylvania Conservancy

   SPECIAL CONCERN RESOURCES OF LAKE PLEASANT(Erie Co.,
                           PA)


SCIENTIFIC NAME                             COMMON NAME

Natural Communities:
BASIN GRAMINOID-FORB FEN                    BASIN GRAMINOID-FORB FEN

CALCAREOUS GLACIAL LAKE                     CALCAREOUS GLACIAL LAKE



Plants of Special Concern:
ASTER BOREALIS                              RUSH ASTER
CARDAMINE PRATENSIS VAR PALUSTRIS           CUCKOOFLOWER
CAREX ALATA                                 BROAD-WINGED SEDGE
CAREX DIANDRA                               LESSER PANICLED SEDGE
CAREX PRAIREA                               PRAIRIE SEDGE
CAREX PSEUDOCYPERUS                         CYPERUS-LIKE SEDGE
CLADIUM MARISCOIDES                         TWIG RUSH
ELEOCHARIS INTERMEDIA                       MATTED SPIKE-RUSH
ELEOCHARIS OLIVACEA                         CAPITATE SPIKE-RUSH
EPILOBIUM STRICTUM                          DOWNEY WILLOW-HERB
GALIUM LABRADORICUM                         LABRADOR MARSH BEDSTRAW
MEGALODONTA BECKII                          BECK'S WATER-MARIGOLD
MYRIOPHYLLUM EXALBESCENS                    NORTHERN WATER-MILFOIL
POLYGONUM ROBUSTIUS                         ROBUST SMARTWEED
POLYGONUM SETACEUM VAR INTERJECTUM          A SWAMP SMARTWEED
POTAMOGETON FRIESII                         FRIES' PONDWEED
POTAMOGETON GRAMINEUS                       GRASSY PONDWEED
POTAMOGETON ILLINOENSIS                     ILLINOIS PONDWEED
POTAMOGETON RICHARDSONII                    RED-HEAD PONDWEED
POTAMOGETON ZOSTERIFORMIS                   FLAT-STEM PONDWEED
RANUNCULUS LONGIROSTRIS                     EASTERN WHITE WATER-CROWFOOT
RHAMNUS ALNIFOLIA                           ALDER-LEAVED BUCKTHORN
RIBES TRISTE                                RED CURRANT
UTRICULARIA MINOR                           LESSER BLADDERWORT


Animals of Special Concern:
BOTAURUS LENTIGINOSUS                       AMERICAN BITTERN
ETHEOSTOMA EXILE                            IOWA DARTER
LEPOMIS GULOSUS                             WARMOUTH
NOTROPIS HETERODON                          BLACKCHIN SHINER




ENVIRONMENTAL ASSESSMENT DIVISION          11              ARGONNE NATIONAL LABORATORY
JANUARY 13, 2000                    FINAL DRAFT     LAKE PLEASANT IMPACT STUDY




WESTERN PENNSYLVANIA CONSERVANCY
      5/14/99




ENVIRONMENTAL ASSESSMENT DIVISION       12        ARGONNE NATIONAL LABORATORY

				
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