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               Saltwater Transport to

Lake Ballard Through a Remnant Valley at

        Hoffler Creek Wildlife Preserve


Alicia Dobyns, Preston Lewis, Jennifer MacDonald, Heather Moore,

        Nathan Rycroft, Gretchen Teed, and Kellie Wright




                        OEAS 441-442

                     Field Studies I and II

                         Summer 2008

Instructors: Dr. David Burdige, Dr. Richard Whittecar, & Amy Pitts

       Department of Ocean, Earth, and Atmospheric Sciences

                     Old Dominion University
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                                            Introduction

       Lake Ballard, located in Portsmouth, Virginia, was originally created as a borrow pit by

the Virginia Department of Transportation in the late 1970’s and 1980’s in order to provide

construction materials for the local highway system (Figure 1). The lake and its surrounding

forested areas are now part of the Hoffler Creek Wildlife Preserve and are currently used for a

multitude of purposes including recreation, education, and research. Hoffler Creek, a brackish

tidal estuary, marks the border to the west and south of the preserve while a residential

community along the James River borders its northern side. Another development of single

family homes frames the eastern edge of the preserve.

       The borrow pit was excavated in two major sections; one was approximately 8 meters

deep on the western side of the current lake while the other was approximately 16 meters deep

and located on the eastern side. During the excavation, it was necessary to steadily dewater the

pit as groundwater flooded in from the shallow Tabb and deeper Yorktown aquifers. The Tabb

aquifer is made up of mostly sand deposited during the late Pleistocene period. The Yorktown

aquifer, which lies below the Tabb, is composed of gravelly clayey sand and large amounts of

shell fragments (Whittecar et al., 2005).

       The pumping of water caused saltwater intrusion into the aquifers which contaminated

local wells. After excavation, the pit filled with brackish water to approximately the point where

it is currently, close to 13 meters at its deepest point. It was expected that after a period of time,

groundwater recharge and precipitation would reduce the salinity of the lake and eventually

return it to a fresh water state. The salinity of the lake has remained relatively constant since it

filled nearly twenty years ago (Wolny, 1999; Allen, 2004).
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                                       Previous Studies

       Numerous research projects in and around Hoffler Creek Wildlife Preserve have analyzed

chemical and geologic aspects. Allen (2004) mapped the spatial distribution of multiple physical

and chemical properties of Lake Ballard. He found the existence of a thermocline and a

halocline which were approximately mirror images of each other, both existing at approximately

6 meters. Allen also found that the pH of Lake Ballard was approximately 9 at the surface and

then decreased linearly as the depth increased. Another finding was that there was a large anoxic

zone at the bottom of the lake which he attributed to poor vertical circulation and seasonal algal

blooms.

       Austin (2005) described her three-year study which ran from 1999 to 2001. She found

that the thermocline existed mainly in the spring and summer months while there was no change

in the vertical temperature gradient during the winter. Her data also showed that chloride and

alkalinity concentrations remained relatively constant from the surface until approximately 7

meters of depth and then increased dramatically. Austin concluded from her data that there is

little to no mixing in the deep sections of the lake but the top 7 meters are well mixed.

       Whittecar et al. (2005) ran a resistivity survey in the surrounding areas of Lake Ballard in

order to find the areas where saltwater existed underground and the effects that saline water had

on the lake. The study found that a majority of the Tabb aquifer is filled with freshwater except

for areas near the James River, the western end of the lake stretching into Hoffler Creek, and a

channel which exists on the South end of the lake in a remnant creek valley (Figure 2). Although

the data from the Yorktown aquifer was limited, it was presumed that the entire area of the

aquifer underneath the study area contained brackish water. The conclusion of the study was that

the major source of salinity in Lake Ballard is the Yorktown aquifer which comes into direct
                                                                                                     4


contact with the deepest areas of the lake. It was also concluded that the broad area of saline

water which exists on the west side of the lake is seeping from the lake into the Tabb and

eventually into Hoffler Creek.

       Boehmer et al. (2005) and Ranck et al. (2006), both summer field study classes,

confirmed the theory that the broad area of saline water on the west side of the lake is

groundwater which flows from the lake toward Hoffler Creek. They accomplished this by

constructing wells and analyzing head data. Ranck et al. (2006) took the study further and found

that the groundwater flow through the Tabb aquifer around the lake is from east to west. By

collecting water samples and recording data from the YSI meter, the study also found highly

reduced water in the deepest parts of the lake, confirming the observations made by Allen

(2004). The 2006 study found that the reduction of sulfate is a major source of alkalinity in the

lake but cannot be the sole source of the high alkalinity levels at the greatest depths.

       Alexander et al. (2007), another summer field study group, concentrated on the sources of
alkalinity in Lake Ballard. Their results showed that sulfate reduction and calcium carbonate
dissolution are the major sources of the alkalinity in the lake. The study concluded that the lake
does not overturn due to temperature-induced density variations between the upper and lower
waters of Lake Ballard. The study left open the possibility of mixing caused by physical
processes. In addition, the study showed that the lake is not a closed system and concluded that a
source could be introducing ions from either the north or the south side of the lake.


                                         Research Goal

       The primary goal of the Summer 2008 Field Study students is to determine the

significance of a remnant valley on the south side of Lake Ballard as a source of saltwater to the

lake. A secondary purpose is to continue the chemical analyses of the lake and the adjacent

aquifers.
                                                                                                      5


                                             Approach

        Previous studies centered on Hoffler Creek Wildlife Preserve indicated that there is a

continuing source of saline water into Lake Ballard. Using the evidence from the Whittecar,

Nowroozi, and Hall (2005) resistivity study and the suggestion of the Summer 2007 Field Study

class that a source of ions may be intruding from the north or south, we chose to concentrate on

an area of low elevation between Hoffler Creek and Lake Ballard on the southern side of the

preserve. The remnant valley, as it is referred to here, was analyzed using various geochemical

and geophysical methods.



                                              Methods

Surveying

        Surveying was used in order to find the elevations of both existing and newly established

wells as well as the water table. By using the lake as a daily local datum, it was possible to find

relative elevations at selected locations around the lake. Measurements were taken with a self-

adjusting level and a stadia rod. Because water level readings were taken from the top of the

casing of each well, the rod was placed on top of the casing of each well where the reading was

then taken. The elevation of the lake was later verified by measuring the creek at a known high

tide and adjusting all elevations relative to sea level.

Vibracore

        We collected five vibracores along the length of the remnant valley located on the south

side of the Hoffler Creek Wildlife Preserve between Lake Ballard and Hoffler Creek. In order to

start the coring in saturated sediments, we used a post-hole digger to excavate a hole down to the

water table. We used a gasoline engine to power the vibrating head attached to six-meter-long
                                                                                                    6


aluminum core tubes. While it was vibrating, we drove the tube into the saturated soil by pulling

down on ropes connected to the head. Using a jack and attaching it to the head, we hoisted the

core tube out of the ground and sliced it into manageable lengths. In the lab we sliced open the

tubes, described and sampled them, and used a scanner to obtain an image of the archived half.

Pore Water Sampling

       After the soil samples were collected from the vibracore columns, a portion was placed

into labeled centrifuge tubes. The samples were positioned in the centrifuge according to weight

so opposing sides were balanced. The centrifuge was turned on for thirty minutes so the water

would settle on top. The water was then poured into a filter leading to a smaller test tube to store

it, with a couple of drops being placed on a refractometer to determine the salinity. Sulfate and

chloride concentrations were determined in the pore water samples using an ion chromatograph.

Sediment analysis

       Sediments that were collected were analyzed visually and by particle analysis. After

being split, each vibracore tube half was visually analyzed for compilation of a stratigraphic

cross section of the valley. Soil samples were taken to the lab for particle size analysis. The

purpose of particle size analysis is to determine D 10 to use for the Hazen permeability

approximation. In order to determine this value, we ran pipette and sieve analyses. We placed the

samples on separate sheets of paper and used the quartering technique to split the sample, then

transferred it into a pre-weighed beaker. We weighed the sample and beaker then subtracted the

weight of both from the initial weight of the beaker. While we did this, we noted the type and

size of any coarse organic particles present. Using 10mL of sodium hexametaphosphate, we

deflocculated each sample individually to disperse the clay particles. To ensure that all samples
                                                                                                    7


were thoroughly washed, we filled the beaker with enough deionized water to cover the sample

in its entirety. The samples were allowed to sit overnight.

       To separate sand from finer sediment we wet-sieved it using a 4-phi sieve. The water was

captured in a 500mL beaker. Once the water flowing into the beaker was clear, the remaining

sample in the sieve was placed in a new, clean, pre-weighed beaker and set in the oven to bake.

       The liquid portions were placed in 1000mL-graduated cylinders and filled up to 1000mL.

For the pipette test, two samples were drawn from each graduated cylinder at intervals of 20

seconds and 2 hours. The sample for 20 seconds was taken 20cm down from the top of the water

level; the 2-hour reading was taken at 10 cm down from the top of the water level. The samples

were then placed in clean, pre-weighed beakers and allowed to bake at 65°C overnight. They

were then removed from the oven and immediately weighed.

       We dry sieved the coarse portion of the oven-dried samples. Using sieves of -1, 0, 1, 2, 3,

and 4 phi, we placed the sample individually in the top of the sieve stack and placed on the sieve

machine for 15-minute intervals. Each pan was emptied into a pre-weighed and labeled boat and

then re-weighed. The weight of the sample was then found by subtracting the tray from the

tray/sample weight.

Well Construction and Development

       To expand our knowledge of the possible groundwater interaction between Hoffler Creek

and the southern side of Lake Ballard, we decided to construct nine wells in a remnant creek bed.

The number and depth of wells was chosen as the result of visual examination of extracted

vibracores and refractometer readings from the pore water samples collected in the cores. At the

location of vibracore 1 (VC1), closest to Hoffler Creek in the range of Spartina alterniflora, we

found three layers containing mixtures of sand or combinations of sand and mud. Wells were
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hand augered to depths of 70 centimeters and 125 centimeters. For a third well, we utilized the

core sample hole by removing fallen sediments from the bottom to a depth of 3.6 meters. The

wells became named 11a, 11b, and 11c respectively. The second set of wells were placed 14

meters inland toward the lake amongst Spartina patens at the location of VC2. A team of four

students with Dr. Whittecar hand augered two wells, numbers 12a and 12b, to depths of 110

centimeters and 3.75 meters, again using the core sample hole drilled ten days earlier for the

deeper well. Four days later, a second team of students assisted in hand augering one well at the

site of VC3, later named well 13a, in a wooded area between the creek and lake. The well,

located 21 meters north of well 12, penetrates to a depth of 2.03 meters. Two new holes were

excavated on the southern side of the road surrounding the lake to show where peaty valley

sediments of the Kennon Formation had been truncated by excavation and the underlying sandy

Tabb Formation appeared near Lake Ballard. We augered well 14a to a depth of 2.05 meters and

well 14b to 3.51 meters. The last well was placed in the location of VC4 on the edge of the lake

within the reeds. Well 15, as it was named, is 2.21 meters deep and was set into Tabb Formation

sands.

         Each well is constructed of a 1¼ -inch diameter PVC pipe riser with varying lengths of

PVC well screen and a cap at the base. We glued extensions together with clear PVC cement

after preparing the surface with purple primer. Once the riser was in place, we filled the hole

with sand to cover the screen, and then added a layer of bentonite to preserve the integrity of

water entering the well. Castings and additional sand filled the remainder of the hole, and then it

was topped by more bentonite at the surface. Details of each construction are located in

Appendix A. Each well was developed using a plunger to improve the flow of groundwater
                                                                                                     9


through the well screen and remove settled matter from the base. A hand-held PVC bailer was

also used to remove all standing water as a way to develop the wells and to test recovery rate.

Water Sampling

       By collecting many water samples from Lake Ballard, Hoffler Creek, and the wells

constructed from this summer as well as prior years, chemical content was analyzed to better

explain groundwater flow. By using a Water Level Indicator, YSI Model 85, bailer, and

Masterflex E/S Portable Sampler, data about water level heads and concentrations of chloride,

sulfate, and saltwater can be observed. Oxygen content, conductivity and temperature is also

observed by the YSI. The following sections detail the YSI, Water Level Indicator, Masterflex

E/S Portable Sampler, and bailer.

YSI Model 85: Oxygen, Conductivity, Salinity, and Temperature

       The YSI is a handheld device that is used to determine oxygen, conductivity, salinity, and

temperature of a water sample at certain depths. The handheld device is attached to a wire with

three electrode sensors on the other end that are lowered into the water at a desired depth. After

the numbers stabilize on the YSI handheld screen, they can be recorded. The oxygen is recorded

in milligrams per liter, the salinity in parts per thousand, and the temperature in degrees Celsius.

This is used on all wells, Lake Ballard, and Hoffler Creek.

Water Level Indicator

       The Water Level Indicator is used to measure the level of the heads in the wells by

indicating the top of the water standing in them. Once the indicator is turned on, the wire with

the sensor on the end is lowered down into the well until a slight buzzing noise is heard. The

reader’s fingers are then placed on the wire at the top of casing measuring the depth to water.
                                                                                                      10


The number on the wire where the reader’s fingers are placed is recorded, signifying the depth to

water.

Masterflex E/S Portable Sampler and Bailer

         The portable sampler and bailer are used to take water samples out of Lake Ballard,

Hoffler Creek, and wells around the lake. The liquid is placed in clean bottles, and taken back to

the lab for testing of chloride and sulfate content. The bailer, used for the wells containing too

little water to sample with the Masterflex E/S Portable, is lowered until it is filled with water. A

ball within the bailer traps water in once the bailer is pulled up, then the water is poured into a

bottle from the other end of the bailer. Each bottle is labeled with a date of when it is taken and

what well number the sample came from. This process is done for all wells including preexisting

wells 1-8 and the nine wells constructed this summer (11a-c, 12a-b, 13, 14a-b, and 15).

         For the samples in Lake Ballard and Hoffler Creek, the portable sampler is used by

clamping the soft part of a tube to the machine and lowering the other end to the desired depth. A

filter is attached to the soft end of the tubing to ensure an accurate sample. The pump switch is

then turned on and the water sample flows through for a moment to clear the tube of any other

water sample. A bottle is then placed at the tip of the filter and filled with the sample. Each bottle

is labeled at what depth, station, and date the sample is taken. A weight must be placed on the

end of the tube in order to ensure it reaches the desired depth without curling.

         All lake samples were taken on June 2nd, 2008 at stations 1-6 (Figure 3). At station one,

samples were taken at depths of 1 to 8 meters and at station two they were taken at depths of 1 to

13 meters. Station three’s samples were collected at every meter between 1 through 6. An

additional collection was made at 6.5 meters for clarification of the thermocline. Then samples

were taken every meter between 7 and 11 meters. Closer to the halocline, sampling was taken at
                                                                                                  11


every half meter at 11.5, 12, and 12.5 meters. Station four was relatively shallow, so samples

were taken at 1 to 4 meters. Station five samples were taken at depths of 1 to 6 meters and station

six samples came from 1 to 6, 6.5, and 7 through 12 meters. Two small boats were used to arrive

at these stations within the lake and an anchor was dropped to keep the boats stationary. The

station’s GPS readings were recorded along with the rest of the YSI data.

Ion Chromatograph (IC)

       Ion Chromatography is used to measure concentrations of major ions in an aqueous

solution. Michael Tswett originally developed the principles and application of ion

chromatography in 1903, and techniques incorporating elluent suppression were perfected in the

1970’s (Dionex Corporation, 2002).

       Within the study area, water samples were collected from Lake Ballard, Hoffler Creek,

and from each well. An ion chromatograph (IC) consisting of Rainin and Dionex components

was used in order to obtain a chemical profile of each water sample from the study area. Each

pore water, lake, creek, and well sample was analyzed for chloride (Cl-) and sulfate (SO 4 2-) ions.

       At the beginning of each run, standards of chloride with concentrations ranging from 0

µM to 1,000 µM and sulfate with concentrations ranging from 0 µM to 2,000 µM were used to

calibrate the IC and create a daily calibration curve. On average, five standards were run prior to

the analysis of samples. The retention time was used to determine the peak associated with a

specific ion, and the area count of the peak used to determine the concentrations of each sample.

       Each sample from the study area was filtered using Whatman 0.45 µm prior to injection.

Approximately 0.5 mL of each sample was injected into the sample loop, where it was combined

with elluent and the ions were allowed to separate from the sample for detection. The

conductivity detector was set at 1000 µS. Some of the samples had to be diluted using deionized
                                                                                                  12


(DI) water in order to obtain a reading for chloride. Mac Integrator II software was set up to

acquire and analyze data from the chromatographs. The computer then displayed the area of

each peak and the data collected from Lake Ballard, Hoffler Creek, and from each well and

vibracore site. Data was then entered into a spreadsheet to calculate the concentration levels in

each sample. The following equation used the displayed area to calculate the concentration of

anions in each of the non-diluted samples.

       Anion Concentration = (Area Under the Curve – Y-Intercept)
                                                  Slope

The concentration levels in the diluted samples were determined using the following equation.

       Adjusted Concentration = (Ion Concentration x Total Volume)
                                   (Sample Volume x 1000)
       **Where: total volume = sample volume + DI water

Titration

       The main purpose of completing a titration is to determine alkalinity. Alkalinity can be

defined as the ability of water to resist a change in pH. When a sample of water is said to have a

high alkalinity, it has a greater ability to resist a change in pH. When a sample has a low

alkalinity, small changes in pH make a difference in the solution and only small amounts of

buffering occur. In the lab, an automated titrator is used to take out human error and give more

accurate results.

       After water samples were taken in the field, the Titrino automated titrator was used to

measure the alkalinity. The machine does this by the addition of small amounts of hydrochloric

acid (HCl) to the water until the sample can no longer resist the change in pH. The equation that

the computer uses to give a value to alkalinity is:

                              alkalinity =                           .
                                                                                                    13


While the samples are tested in an automated machine, it is possible to get similar results with a

manual titration and use this same equation to obtain alkalinity numbers.

       The Titrino pH electrode was calibrated using buffers with a pH of 4, 7, and 10. In order

to verify that the calibration of the machine was accurate, a slope close to a standard should be

generated. After we calibrated the machine we obtained a slope that was reasonably close, which

meant that we could begin titrating lake samples. To begin the titration, two grams of the sample

were placed into a 4 mL vial with a small stir bar. The small amount is used so that a volume of

HCl could be added and not overflow. After the correct program was downloaded to the

machine, the weight of the sample could be entered in to the machine so that the alkalinity could

be calculated. If these pieces of information are entered wrong it is possible that the end point of

the titration could be over-shot and require a second run. During the process, the downloaded

program placed a predetermined volume of HCl into the vial, and then small additional doses

were metered periodically. During the titration the pH is constantly measured. When the pH is

unable to resist the change, the titration is complete.



Ground-Penetrating Radar (GPR)

       Ground-Penetrating Radar was used in attempt to estimate the thickness and width of

fluvial sediment deposited in the remnant valley and to determine the possible presence of

saltwater. This radar, a PulseEKKO 100, sends repetitive pulses of electromagnetic waves in

frequencies of 100 MHz into the ground. Once the waves have reached the reflectors or changes

in strata, they reflect a pulse back to the surface. While the leading paddle, the transmitter, sends

the signal into the ground, the second paddle, the receiver, collects the waves bounced back to

the surface. Data is transferred to an attached computer until it can be processed. Along each
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GPR transect, the spacing of the antennae, or the transmitter and receiver, was 1.0 m and the step

distance was 0.5 m. After the relative elevations of points around the lake and across the remnant

valley were surveyed with a level and rod, GPR transects were run along the road on the south

side of Lake Ballard across the top of the remnant valley (LB266 TP), down the middle of the

remnant valley, across the valley near the creek (LBI2), and a control on the north end of the

parking lot (LBLOT). A common mid-point test (LBCMP) for velocity was shot on the east side

of the lake where the transmitter and receiver were moved 1.0 m apart each run, the final spacing

distance equaling 10 m (Figure 4). During the run along the road, the transmitter and receiver at

each shot was placed 1.0 m apart along a 140 meter distance, with a break in the run made at the

60 meter mark. For the run across the creek, the transmitter and receiver set at 1.0 m apart shot a

total distance of 65 meters. The run along the North end of the parking lot was run the same way

along a total distance of 40 m. The run down the middle of the remnant valley was aborted due to

rain and battery problems.

       In the lab, files were created for each transect and placed in the radar program. A graph

was then created and the velocities for each were changed to fit a better slope and account for

depth of radar penetration. The elevations from the survey were also entered into the chart. Data

were processed with PulseEKKO software, including modifications for topography.



                                             Results

Mechanical Sediment Analysis

        Four vibracores were taken from the area through the remnant valley (Figure 5). The

vibracores were then sealed and taken back to the lab for further analysis. Upon visual analysis,

the core closest to the creek (VC 1) was observed to be reduced mud with fibrous organics mixed
                                                                                                  15


throughout. Vibracores two (VC 2) and three (VC 3) both showed visible signs of mud with

mixed organics. Some sand was present in the upper layers of each core. The fourth vibracore

(VC 4) was extracted closest to Lake Ballard and contained mainly construction fill with Tabb

sands at the bottom. Pictures were taken of each core and pieced together in order to assemble a

complete cross-section (Figure 6).

       Using the cross-section constructed from the visual interpretations of the cores, a

geologic interpretation was constructed (Figure 7). The peat- and mud-rich sediments throughout

the remnant valley is the Kennon Formation, deposited during the present sea-level rise

approximately 10,000 years to present. This formation consists of mainly tidal marsh fill. Close

to Lake Ballard, we drew a thick, black vertical line where we estimate the location of the wall of

the remnant valley. On the north side of the thick, black vertical line are Tabb Formation

sediments. This sediment was deposited 120,000 years to 70,000 years ago during the last

interglacial time period. It contains clean sands with pebbles. The thick horizontal black line over

the Kennon and Tabb sediments is a geologic unconformity separating anthropogenic fill from

the Kennon and Tabb. The anthropogenic fill consists of agricultural runoff from farmlands and

mining waste from the removal of Tabb sands.

       From half of each vibracore, samples were extracted and used for particle size analysis.

For vibracore one, two samples were taken at 80-90 cm and at 270-280 cm. The first sample has

a very low percentage of very coarse sand with the most abundant grain size being medium-fine

sand. In the second sample, medium-fine grained sand is also the most abundant grain size with

very coarse sand being the least abundant.

       From VC 2, two samples were taken at 90-100 cm and 200-210 cm respectively. For 90-

100 cm, the most abundant grain size is silt followed by clay with the least abundant being very
                                                                                                  16


coarse sand. The second sample was well sorted. The majority of grain sizes were between

medium-fine sand to silt.

        The third vibracore was extracted from the middle of the forest and also at the highest

elevation. The samples were taken from 50-60 cm and 130-140 cm. In the shallow sample, the

majority of sediment was silt. Very fine sand was not as abundant as the rest of the sediment.

The deeper sample showed the majority of grains being medium-fine sand and contained little

clay.

        For Well 14, we hand dug down to 3.5 meters. Two samples were taken from the sand

and mud. The sand showed a majority of medium-fine sand grain and very coarse sand to be less

abundant. The mud section of the hole showed a very high percentage of silt with very little

sand.

        VC 4 came from the shore of Lake Ballard. The sample from 0-10 cm showed the

majority being medium-fine sand. The sample from 120-130 cm revealed that medium-fine sand

was the majority, followed by very-fine sand, and medium sand. The least abundant grain size at

this level was silt.

        Details of each particle size analysis are found in Appendix B.

Head Data/Rainfall

        Head data was collected from the nine new wells in the remnant valley and from the

existing wells around Lake Ballard. Four data sets were taken from wells 11 through 15,

beginning approximately one week after construction (Figure 8). On June 23, 2008, the depth to

water was the greatest in each of the wells. Two weeks later, on July 7, wells 11 and 12 exhibited

a shallower water table. Wells 13, 14, and 15 all remained approximately the same. Three days
                                                                                                     17


afterwards, water rose near the surface at well 12. The wells closer to Lake Ballard remained at

similar levels as on the previous sample dates. On the last day of testing, July 14, levels in the

wells near Hoffler Creek had resided toward the original head levels.

       Measurements of depth to water were collected on the west side of Lake Ballard on three

of the same dates as the remnant valley. The east side was tested twice. Separating the data from

the shallow wells that penetrate the Tabb Formation, results showed a general decrease in head

from east to west (Figure 9). The two deep wells that sample the Yorktown aquifer, one on the

west side of the lake, and one on the east gave elevations lower than the lake (Figure 10).

       Rainfall data for the period of the study was collected from www.weather.com. Very

little precipitation occurred during the first two weeks in the field. On June 17, accumulation of

over two centimeters fell. Rain became more common as June ended and July began. Between

the first and second head sampling dates, on July 4, over three centimeters were recorded by the

weather service. Details of each accumulation were graphed along with our key field dates

(Figure 11).

Tide Data

       Based on a conversation with a Hoffler Creek Wildlife Preserve Foundation member, we

know that at only one time, during hurricane Isabel in September 2003, has saltwater from the

creek flooded over the berm reaching 2.4 meters above sea level, and spilling into Lake Ballard.

This information led us to research how tides influence the presence of saltwater in the lake on a

more frequent basis.

       Hoffler Creek is a tidal creek that branches off of the James River. The creek is greatly

affected by the rise and fall of the Chesapeake Bay’s semidiurnal tidal fluctuations. Using the

National Oceanic and Atmospheric Administration (NOAA) website, we were able to browse
                                                                                                   18


through an immense resource of historic tide data from various locations throughout the

Chesapeake Bay watershed. The nearest location to Hoffler Creek that records regular tidal data

was located at Sewell’s Point which is in Norfolk, VA. Maps found on Google Earth indicate

Hoffler Creek is approximately 5 miles from Sewell’s Point (Figure 12). To use the vast database

we had to first ensure that the Sewell’s Point data would correspond to the tidal fluctuations

occurring at our location at Hoffler Creek. We took tidal data from October 5-6, 2007 at Hoffler

Creek and compared it to the tidal data from Sewell’s Point on those same days (Figure 13).

With these results we were able to calculate a lag time of 3 hours and 42 minutes. We then

normalized the tide readings from Sewell’s Point and Hoffler Creek (Figure 14). The results

prove that the tidal record taken from Sewell’s Point correlates with and can be used to predict

the tide levels occurring at Hoffler Creek. This correlation now opens up for us and future

researchers an extensive tidal database.

       Using the NOAA database and its high tide record, and comparing this with the

elevations of the remnant valley which are known through surveying, we can estimate how far

the saltwater from the creek rises in the remnant valley that connects the lake and the creek.

During the time we took water samples, there was a significantly higher storm tide of 1.1 meters

on the 17th of June (Figure 15), which correlates with our rainfall record. This storm tide rose

past the surface at well 12.

Pore Water & Well Profiles

       In order to help validate the remnant creek valley as a source of ions into Lake Ballard, it

was necessary to examine the soils and groundwater in that area. Using the vibracore, four

samples were taken of the soil at locations VC1, VC2, VC3, and VC4. These locations

correspond with the locations of wells 11, 12, 13, and 15. Well 14 was constructed at a point
                                                                                                19


where no core sample was taken, therefore, there are no pore water samples from that site. Pore

water samples were taken from multiple sections in each core.

       A refractometer was used to find salinity readings immediately after centrifuging each

pore water sample (Figure 16). The result showed a decrease in salinity with depth and across the

remnant valley from Hoffler Creek towards Lake Ballard.

       The ion chromatograph was used in order to find the concentrations of both chloride and

sulfate. Because we were most concerned with the areas which lie just above the confining mud

bed, we mainly took into account the samples which originate from that area. Also, several of

the wells which we constructed (11b, 12a, and 13) were placed specifically in the area above the

mud layer so that we could observe the groundwater which flows at that level. The pore water

sample from VC1 taken at a depth of 85 cm was found to have a chloride concentration of

141.04 mM and a sulfate concentration of 385.09 mM. The sample from VC2 taken at a depth

of 95 cm had a chloride concentration of 73.32 mM and a sulfate concentration of 0.26 mM. The

sample from VC3 taken at a depth of 95 cm had a chloride concentration of 37.89 mM and a

sulfate concentration of 0.12 mM (Figure 17). The well water samples in these areas were found

to have very similar concentrations. On July 14th, wells 12 and 14 were found to have much

higher chloride concentrations.

Lake Profiles

       Water samples from Lake Ballard were analyzed in order to determine the depth,

temperature, salinity, dissolved oxygen, sulfate, chloride, and alkalinity measurements. The YSI

meter was used to determine the levels of temperature, salinity, and dissolved oxygen. The data

was then plotted into depth profiles of temperature and salinity values. The temperature

decreased consistently with depth, although at approximately 12 meters the temperature of the
                                                                                                    20


lake water began to increase slightly (Figure 18). The salinity remained fairly stable until around

10.5 meters where it began to drastically increase (Figure 19). Dissolved oxygen data showed

that the anoxic zone of the lake has become more shallow over the past year, beginning at 6.5

meters in depth (Figure 20).

       The ion chromatograph determined concentrations of the sulfate and chloride levels in the

samples taken from the lake. These concentrations, when plotted in a depth profile, showed that

sulfate decreases slightly with depth and that chloride increases slightly until 10 meters. At that

point, sulfate ions drop significantly while chloride increases (Figure 21). The alkalinity data

measured by the Titrino Titrator was recorded against the depth of the lake. The data showed

that there was a dramatic increase in alkalinity values at 10.5 meters.

Well Recovery Rate

       After developing the nine new wells on July 7, they were emptied with a bailer to test the

recovery rate. Both shallow wells close to Hoffler Creek could not be emptied because the water

returned before it could be withdrawn completely. The deep well at the same location, number

11c, did not recover during the testing period. Well 12a did not refill completely after thirty eight

minutes. A malfunction of the plunger line lost the developing tool in well 12b, making it

impossible to test for recovery rate. Wells 13, 14a, and 14b all refilled completely between tests.

The well closest to Lake Ballard, well 15, did not return to its initial water level within one hour.

Details of the test are listed in Appendix C.

Ground Penetrating Radar (GPR)

       The Ground Penetrating Radar was used to determine the presence of a valley shape and

saline water within our area of interest, the remnant valley. In order to find this, 4 tests were run:

velocity test between the pavilion and Lake Ballard, background check in the parking lot, and 2
                                                                                                  21


runs across the remnant valley (Figure 4). For the velocity run, a common midpoint analysis had

to be run in order to find a velocity of the pulse through these materials. Over a 10 meter run, it

took 35 nanoseconds for the radar to bounce back to the surface or receiver giving us a velocity

of 10 m per 35 ns or 0.14 m/ns (Figure 23). The background check in the parking lot was done to

determine how far the GPR penetrates in a non-saline environment. Figure 24 shows the

penetration to be about 10 meters down, but strangely attenuates the rest of the run. The run done

nearest to the creek (Figure 25), shows the radar penetrating about 2 meters down along the sides

or tops of the valley, whereas the middle of the valley shows about just barely a meter. Figure

26, the run along the road, shows a penetration of 2 to 3 meters on the sides of the valley and

about 1 meter in the middle of the valley.

***ANALYSIS NOT EDITED***

                                             Analysis

Sediment Analysis

       After the particle size analysis had been conducted, D10 could be found for the Hazzen

Approximation. We used the Hazzen Approximation in order to estimate permeability and ease

of groundwater flow. D10 was collected for samples containing less than 10% mud and then

displayed graphically on the Hydraulic Conductivity graphic (Figure ). It was found that the

easiest conduit for groundwater to move from Hoffler Creek to Lake Ballard would be above the

mud layer and, by density flow, sink through the Tabb sediments and into the depths of Lake

Ballard.

Hydro-geologic Sediment Analysis (Preston)

       When trying to understand how salt can travel from Hoffler Creek to Lake Ballard the

subject of diffusion was brought up as a possible explanation. When looking at the sediment
                                                                                                       22


cores diffusion is seems like a sound explanation the problem. However, after plugging in the

values from Lake Ballard into the Einstein-Smoluchowski equation I have a much different idea

of how long it takes for ions to diffuse though sediment. When solving the equation, distance

was one of the variables that needed to be accounted for. To do this, measurements were taken

from Google Earth at the high tide, low tide, and an average of the two in order to get

representative distances to consider. After plugging in the variables that we needed for the

equation, it was evident that it would take orders of magnitude longer than the lake has been

there. Going back to the equation I rearranged the variables to solve for distance, given that the

lake has been there for 20 years in order to see how far ions could have moved since the lake was

created. The equation showed ions could have only moved a distance of 84 cm, not nearly

enough to have an effect on the salinity of the lake. This same equation was used to show the

time it would take ions to move from Hoffler creek to the Lake on the west to east direction.

Once again, diffusion could be ruled out as a possible source of salt in the lake. Originally

diffusion was an explanation for the salinity of the lake. However, the equations results tell us

that it is safe to say diffusion is not possible in the time that the lake has been there. This will

allow us to concentrate our efforts elsewhere to find the source of salinity.

        After all of the vibracore samples were separated and run through a series of particle size

analysis, it was possible to use the Hazen approximation. This is an equation that uses an

empirical equation to estimate the conductivity of particular sediment using effective grain

size            ). When using this approximation only samples that have 10 percent or less mud

can be used to obtain reliable results. The results that are obtained from this method are given in

cm/sec, which can later be converted into an actual velocity. Once the permeability (K) is

obtained then that value can be plugged into the seepage velocity equation to get the approximate
                                                                                                      23


velocity of the ground water. This equation is Vs=       , where “K” is permeability, “ne” is

porosity (obtained from a table of values), “dh” is the difference in head between two wells and

“dx” is the change is distance between two wells. With results from this equation we will be

able to determine of the sediment in the area has the ability to move water at a velocity that can

move saline water from the creek to the lake. In order to get values from the seepage velocity

equation that were reliable, the correct gradients had to be choose. To do so, the change in head

was determined from a single day of sampling in which the head in well 12 was higher that that

of well 15. The change in head (41cm) divided by the distance (50m) gave us a value that we

could complete the equation with. After plugging in all of the values it was determined that

ground water has the ability to flow through the system in the order of several days. Using other

gradients obtained from the wells and the distances gave the same results, orders of days not

weeks or months (salt flow rate figure). The seepage velocity equation works very well for our

project. This is because all of the variables that are used in the equation are site specific. This

allows us to use a range of particle sizes and varying gradients to see if it is even possible to get

through flow from the creek to the lake.

Well and Creek Discussion Section (Nate)

       The data retrieved by the YSI meter and water samples on each of the thirteen wells

studied showed the temperature, salinity, chloride, sulfate, and dissolved oxygen of the

groundwater at the specific depths of the screens in each well. The data shows that there is a

clear pattern of salt water in both the Tabb Aquifer on the West side of the lake and in the

remnant creek valley on the South end. The analyses of water samples from wells which

penetrate to the top of the mud layer in the Kennon Formation (Wells 11b, 12a, 13, and 14a)

show a pattern of steadily decreasing salinity from the well closest to Hoffler Creek (Well 11b;
                                                                                                   24


8.8 ppt) to the well which is closest to the lake (Well 14; 3.3 ppt). Because the mud layer was

excavated during the initial construction, Well 15 does not come into contact with the mud layer

hence the reason that it is not included in the analysis. The wells which border the west side of

the lake show a pattern of salinity which indicate the possible movement of ions across a

gradient from the creek (25.0 ppt) through Well 8 (2.9 ppt) and Well 1 (2.4 ppt) and possibly into

the lake (2.9 ppt). Of course, this data is not necessarily conclusive because well 8 and well 1

are at different depths with Well 8 located just above the Yorktown Formation and well 1 being

fairly shallow into the Tabb. The difference in depths could affect the salinity because the more

saline water will tend to fall to the bottom of the formation while less brackish water will remain

higher in the column. Also, head data (discussed earlier) shows that advection actually opposes

the concentration gradient thereby retarding the diffusion of ions into the lake. In the well

samples, there were several odd chloride concentrations found in Wells 12 and 14 where the

chloride levels were much higher than expected. These findings occurred after several days of

heavy rains leading to the possibility that salt which was deposited in the soils was dissolved by

the rain and then affected those wells.




                                             Conclusions



                                            Future Work

                                   •      Salt Budget for Lake Ballard

                              •   Residence time of ions in Lake Ballard

                             •    Continued GPR studies around the lake
                                                                        25


•   To measure water table levels in the valley during a storm surge.

                   Year round lake sampling
                                                                                                              26


                                                       Figures




Figure 1. Lake Ballard is located within Hoffler Creek
Wildlife Preserve in Portsmouth, Virginia. The site lies
within Virginia’s Coastal Plain.




      Figure 2. The shaded area to the west and northwest of Lake Ballard in addition to lobes at the north and
      south indicate areas of brackish water found during the Whittecar et al. (2005) resistivity study.
                                                                                                     27




Figure 3. Locations of Lake Ballard samples taken on June 2, 2008 are pictured.




      GPR Paths
                         Velocity Test Run: LB-CMP

                                  Parking Lot: LBLOT




                     Southside Rd: LB 266 TP

                Bottom of Remnant Creek Valley:
                          LBI12TOPO

Figure 4. This shows the paths run for the GPR including a velocity run, background check in the parking
lot, and two runs across the remnant valley.
                                                                                                    28




Figure 5. Vibracore samples were extracted along the southern side of Lake Ballard. The locations
became the sites of the wells constructed during the Summer 2008 Field Study.
                                                                                                      29




                      VC 1         VC 2           VC 3             VC 4
             0
             M
                                                                                     Vibraco

   Mud
   layer
             1
             M




               2
               M

Figure 6. Vibracores scans show detail used in visual analysis. A layer of mud is indicated above between
the blue lines. Scale for the length of each vibracore is indicated on the left.
                                                                                                                              30




Figure 7. This stratigraphic cross-section of the remnant valley is oriented with Hoffler Creek to the left,
off the diagram, and Lake Ballard to the north at the right. Vertical lines represent the 5 primary holes
used for sediment analysis.



                                                   Horizontal Distance from Mean Tide (m)


                                        10         20        30        40          50             60
                       2
                                                                                   14a
                                                                  13                                          6/23
                                                                                                              7/7
                            11a              12a
                       1
                                  11b                                                                         7/10
                                                                       FILL                                   7/14
   Elevation (m)




                                                                                                   15



                   0                                                                                          Lake
                                                                                                             Ballard

                                                                                                             Lake Elev.
                                                                    Unconformity
                       -1                                                                                     (0.36 m)

                                                                                                        Qt

                   -2
                                                                                         Kennon/Tabb
                                                                                           Boundary
                                                        Qk
                   -3


                                                         Hydraulic Head Data
                   S                                                                                                      N
                                                             Summer 2008
Figure 8. Depth to standing water in wells was recorded on four sampling dates.
                                                                      n/a
                                                                      1.19 m                                                                  2.13 m                      31
                                              1.44m                   0.26 m                                       1.18 m                     0.85 m
                                              Dry
                                              Dry               2
                                                                    7 8             1.51 m
                                                                                                   Results
                                                                                                    0.98 m
                                                                                                                   0.76 m
                                                                                                                   -0.13 m
                                                                                                                                         5
                                                                                                                                              0.37 m
                                                                                                                                               6
                                                                          1         0.30 m          0.76 m                     3
                                                                                    0.24 m          0.36 m
                                                  0.0 m

                                              HCk                                                                                                         Qt
                                                           Qt
                                              Qk                                                                               Groundwater Flow
                        Elevation (m)




                                        Density Methods
                                                                                                                   Ty
                                                                                                                                                                 E
                                                  W

                                              0        90           180        270     360    450   540     630    720   810       900       990     ’
                                                                                                                                                   1080   1170   1260

                                                                                                          Distance (m)                              Hydraulic Head 2008
                                                                                                                                                          Summer 2006
                                                                              Hydraulic Head and Groundwater Flow                                         Summer 2007
                                                                                          Tabb Aquifer                                                    Summer 2008
                                                                                          Summer 2008


Figure 9. Well heads around Lake Ballard along the East to West cross-section indicate
groundwater flow in the shallow Tabb aquifer and a general drop in water level.



                                                  n/a                         Hydraulic Head and Groundwater Flow
                                                                                                                                                     1.03 m
                                                  1.37 m                                Yorktown Aquifer
                                                  0.22 m
                                                            2
                                                                7 8
                                                                                               Results
                                                                                          Summer 2008
                                                                                                                                         5    6
                                                                                                                                                     0.82 m
                                                                                                                                                     -0.13 m
                                                                      1
                                          HCk                                                                                  3

                                              0.0 m

                                                                                                          0.98 m
                                                                                                                                                          Qt
        Elevation (m)




                                                                                                          0.76 m
                                                       Qt                                                 0.36 m
                                          Qk


                           Density Methods
                                                                                                                   Ty
                                                                                                                                                                 E
                                              W

                                          0           90        180           270     360    450    540    630     720   810       900       990     ’
                                                                                                                                                   1080   1170   1260

                                                                                                      Distance (m)
                                        Summer 2006
                                        Summer 2007
                                        Summer 2008

Figure 10. Hydraulic head data from the Yorktown aquifer wells indicate a decrease in water
level, similar to the Tabb wells. Data for groundwater flow is inconclusive.
                                                                        Portsmouth Rainfall 2008
                                                                          Portsmouth Rainfall 2008
                                                                                                                                                                      32
                  4.00
                  3.50
                  3.00
   Amount(cm)cm
                  2.50
          in

                                                                                                                                                   s
                  2.00
   Amount



                  1.50        v/s                                                         s                                      s      s
                                                            w          w
                  1.00
                  0.50
                  0.00
                          1   2   3 4   5 6   7   8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

                         June                                                                   Day            July

                         V – Vibracore
                         W – Well Construction
                         S – Sample Dates



Figure 11. During the two months of field study, several rain events in Portsmouth occurred.
Dates of interest are indicated by arrows. Vibracore sampling was taken on June 2, 2008. Well
construction occurred on June 12 & 16. Water samples and/or head data was collected June 23
through July 14, 2008.




                                                                                 Sewell’s Point Tide
                                                                                 Observation Station




                                                                 James River




                                                   Hoffler
                                                   Creek
                                                   Preserve
                                                                                                            Elizabeth
                                                                                                            River




Figure 12. Map of James River and study area show proximity of NOAA Sewell’s Point Tide Observation
Station to Hoffler Creek Wildlife Preserve. (photo courtesy of Google Earth)
                                                                                                                                                                                                          33



                                        Comparing Tidal Readings From Sew ells Point and Hoffler Creek On 10/5/2007-10/6/2007

                           1.4
                                                                                                                                                                                          Tidal
                           1.2                                                                                                                                                            Readings at
                                                                                                                                                                                          Sewells Point
                                                                                                                                                                                          from NOAA
                            1
   Tide Levels in Meters




                                                                                                                                                                                          Tidal
                           0.8                                                                                                                                                            Pressure
                                                                                                                                                                                          Readings
                                                                                                                                                                                          From Hoffler
                           0.6
                                                                                                                                                                                          Creek
                                                                                                                                                                                          Average
                           0.4                                                                                                                                                         (Sewell’s Pt)


                           0.2
                                                                                                                                                                                          Average
                            0                                                                                                                                                          (Hoffler Creek)
                                 0:00
                                        2:24

                                               4:48
                                                      7:12
                                                             9:36
                                                                    12:00
                                                                            14:24
                                                                                    16:48
                                                                                            19:12
                                                                                                    21:36
                                                                                                            0:00
                                                                                                                   2:24
                                                                                                                          4:48
                                                                                                                                 7:12
                                                                                                                                        9:36
                                                                                                                                               12:00
                                                                                                                                                       14:24
                                                                                                                                                               16:48
                                                                                                                                                                       19:12

                                                                                                                                                                               21:36
                                                                                            Time in Minutes


Figure 13. The tidal pressure readings taken at Hoffler Creek between October 5 & 6, 2007 show
a wave curve similar to readings from Sewell’s Point on the same days.
                                                                                                                                                                                                                                                                         34



                                                   Comparing Tidal data from Sewell's Point and Hoffler Creek with adjusted lag time and adjusted
                                                                                         height difference

                         1


                        0.9


                        0.8

                                                                                                                                                                                                                                                            Tide data from
                        0.7                                                                                                                                                                                                                                 NOAA
 Tide level in meters




                        0.6


                        0.5


                        0.4


                        0.3
                                                                                                                                                                                                                                                            Tide data from
                                                                                                                                                                                                                                                            Hoffler Creek
                                                                                                                                                                                                                                                            adjusted for a 3:42
                        0.2                                                                                                                                                                                                                                 lag time and a
                                                                                                                                                                                                                                                            0.399 tidal
                                                                                                                                                                                                                                                            difference
                        0.1


                         0
                                                                         10:12
                                                                                 11:54
                                                                                         13:36
                                                                                                 15:18
                                                                                                         17:00
                                                                                                                 18:42
                                                                                                                         20:24
                                                                                                                                 22:06
                                                                                                                                         23:48




                                                                                                                                                                                    10:00
                                                                                                                                                                                            11:42
                                                                                                                                                                                                    13:24
                                                                                                                                                                                                            15:06
                                                                                                                                                                                                                    16:48
                                                                                                                                                                                                                            18:30
                                                                                                                                                                                                                                    20:12
                                                                                                                                                                                                                                            21:54
                                                                                                                                                                                                                                                    23:36
                              0:00
                                     1:42
                                            3:24
                                                    5:06
                                                           6:48
                                                                  8:30




                                                                                                                                                 1:30
                                                                                                                                                        3:12
                                                                                                                                                               4:54
                                                                                                                                                                      6:36
                                                                                                                                                                             8:18




                                                                                                                         Time in minutes




Figure 14. When adjusted for time lag and normalized, the overlain tidal data curves from
Sewell’s Point and Hoffler Creek are virtually identical.
                                                                                                                                           35



                                    High and Low tidal levels at Sewell’s Point in Norfolk, VA

                                                      June 1st - July 31st 2008




Figure 15. Observed water level on June 17, 2008 was approximately 1.1m at Sewell’s Point,
according to NOAA. This coincides with a large rainfall event in Portsmouth.

                                                      Salinity for Pore Water Samples (ppt)
                                                                   Summer 2008
                                                          Horizontal Distance from Mean Tide (m)


                                          10         20             30               40              50            60
                               2
                                                                                                          Pore Water June 2, 2008


                               1                                                5

                                    13           7
           Elevation (m)




                                                 6                              2
                           0                                                                                      N/A
                                    10           5                                                                         Lake
                                    5           3.5                             0     Unconformity                N/A
                                                                                                                          Ballard
                                                                                                                          Lake Elev.
                               -1                                                                                          (.36 m)
                                    2                                          0.5                                 N/A
                                                 2                                                                   Qt
                                    1
                               -2
                                                                                                          Kennon/Tabb
                                    2                                                                       Boundary
                                                0.5         Qk
                           -3



                           S                                                                                                           N

Figure 16. Salinity measurements from pore water samples were taken using a refractometer.
                                                                                                                                        36


                                            Chloride Averages for Pore Water/ Wells (mM/L)
                                                            Summer 2008
                                                        Horizontal Distance from Mean Tide (m)


                                       10          20             30            40               50            60
                         2
                                                                                                      Pore Water June 2, 2008
                              Hoffler Creek                                                           Well Water June 23, 2008
                              270.51
                         1    290.54
   Elevation (m)




                                                                                                                      42.48
                              141.04                                                         N/A
                                              73.32                      24.83              40.30                     46.85
                     0        157.48          100.77                     33.22                                          Lake
                               83.02                                                                                   Ballard
                              113.22                                         Unconformity
                                                                                                                       Lake Elev.
                         -1                                                                                             (.36 m)
                                                                                                             N/A
                                                                                                                Q
                                                                                                            12.06 t
                         -2
                                                                                                      Kennon/Tabb
                                                                                                        Boundary
                                                          Qk
                     -3



                     S                                                                                                              N

Figure 17. Chloride data for the creek, lake, and wells


                                                        Temperature vs Depth

                          0        5          10           15          20            25          30           35        40
                    0
                    -2
                    -4
  Depth (m)




                                                                                                                                2006
                    -6
                                                                                                                                2007
                    -8
                                                                                                                                2008
                   -10
                   -12
                   -14
                                                                Temperature (C)




 Figure 18. Lake Ballard temperature vs. depth
 profile. The 2008 thermocline mirrors prior years
 when considering that each sample was taken under
 slightly different conditions. Of particular note is
 the small increase in temperature at the bottom of
 the lake.
                                                                                                      37
                                                Salinity vs Depth

                       0.0   1.0       2.0        3.0            4.0        5.0        6.0   7.0
                   0
                  -2
                  -4
     Depth (m)




                                                                                                   2006
                  -6
                                                                                                   2007
                  -8
                                                                                                   2008
                 -10
                 -12
                 -14
                                                     Salinity (ppt)


Figure 19. Lake Ballard has a halocline at approximately 11 meters. Summer 2008 data is consistent with
previous summer studies.



                                       Lake Ballard Data
                                         Dissolved Oxygen vs Depth

                       0           5            10                     15         20          25
                  0
                  -2
                  -4
   Depth (m)




                                                                                                   2006
                  -6
                                                                                                   2007
                  -8
                                                                                                   2008
                 -10
                 -12
                 -14
                                             Dissolved Oxygen (mg/L)


 Figure 20. The profile for dissolved oxygen in Lake Ballard shows a significant difference in
 depth at which the level drops to zero mg/L when compared to 2006 and 2007. 2008
 measurements are similar to those taken by Allen (2004).
                                                                                             38




Figure 21. Ion chromatograph data for Lake Ballard. Sulfate decreases below 10 meters. Chloride
ions increase at approximately the same depth.
                                                                                                 39


                                    Well Data 7/07/2008
                                  Depth
                                    to
                                  Water     Minutes
                                  (DTW)     between    Recovery
                        Well #      ft       DTW        DTW ft     Comment
                                                                   unable to
                           11a       1.37         18        1.49   empty
                                                                   unable to
                           11b       1.45         23        1.51   empty
                           11c       3.08         16       11.33   slow
                           12a       2.49         38        4.78   slow
                           12b       4.66
                           13a       5.11         49        5.11
                           14a       6.31         66        6.28
                           14b       6.55         70        7.05
                            15       1.97         59        4.94   slow

Figure 22. Well recovery rates. Shallow wells closest to Hoffler Creek could not be emptied by
bailing. Deep well 11c, shallow well 12a, and well 15 all failed to recover to their initial water
levels. Well 12b could not be tested due to a line failure that left the plunger in the well.




            GPR-Velocity Test Run-LBCMP

                                            10m/35ns= 0.14 m/ns
                                        Velocity Test Run: LB-CMP
                                                              Parking Lot: LBLOT




Figure 23: This shows the velocity run where a common midpoint analysis was run to find the
velocity through materials in this area.
                                                                                             40




                     GPR-Parking Lot-LBLOT




Figure 24: This shows a background check done in the parking lot at Hoffler Creek Wildlife
Preserve and was done to show how far the radar penetrates the ground in a non-saline
environment, here being about 10m.



                  Bottom of Remnant Creek
                      Valley-LBI2TOPO



                                        Well 11c                                       0


                                                                                      2


                                                   8.8ppt                             4

                                                   5.1ppt
                                                                                      6




Figure 25: This run was done across the remnant valley closest to Hoffler Creek. The shows
salinity concentrations in Well 11c, with a mud layer 2 meters down.
                                                                                               41




             GPR-Southside Road-LB175TO


                                                                                          0
                                        Well 14a



                                                3.3ppt

                                                2.9ppt                                    5




Figure 26: This run was done along the south side road around Lake Ballard showing us the
salinity concentrations in Well 14a and mud layer 2 meters in depth. Valley strata are also very
well present here.
                                                                                                        42



            Hydraulic Conductivity of Core
                      Samples




Figure 27. Using D10 and the Hazen Approximation, the permeability of sediments along the remnant
valley could be calculated. The most permeable areas are indicated by the largest octagons. The small
squares show where samples were tested but contained more than 10% mud, so they fell outside of the
test’s range of computation.




         Figure 27. Calculation of time for saltwater to travel through a variety of sediment sizes
                                                                                                                                           43




                                                                              Stratigraphic Controls:

                                                    10             20           30           40           50        60
                                  2

                                          Storm surge/Spring tide
                                  1
                                                                                            FILL

                              0                FILL


                               -1

                                                                                                                         Qt
                               -2
                                                                    Qk

                               -3




Figure 28. In the event of a storm surge or spring tide, the saltwater of Hoffler Creek could cover ground
above well 12 then travel through the sediments in the pattern indicated.




                 Sulfate vs. Chloride with Seawater Mixing Line
                             15.00



                             13.00



                             11.00
              Sulfate (mM)




                              9.00


                                                                                                                    SULFATE VS. CHLORIDE
                              7.00                                                                                  LAKE BALLARD
                                                                                                                    Linear (MIX LINE)


                              5.00



                              3.00



                              1.00


                                      0   20   40   60   80   100 120 140 160 180 200 220 240 260 280 300 320 340
                             -1.00

                                                                  Chloride (mM)

                                      Figure 29. Sulfate vs. Chloride data indicates diluted seawater.
                                                                                                                          44


                               Appendix A: Well Completion Reports
                                            Well Completion Report
Project: Lake Ballard Ancient Creek                       Well Name: 11a
Location: 36.89108N, 76.39969W                            Constructed by Alicia Dobyns, Jennifer MacDonald,
Top of casing elevation: 1.06 m (3.49 ft)                 Nathan Rycroft, Gretchen Teed, Dr. Rich Whittecar
                                                          Construction Date: 06/12/08
Scale (cm)          Borehole Information                           Well Construction Information



                                                                                     Above ground riser of 40 cm

     0              0-10 cm: mud & roots (initial hole)

                                                                                  Bentonite

     50             10-70 cm: gray sand
                                                                                  Filter pack of medium sand


    100



    150



    200



    250



    300



    350


                 Hand augered to 0.70 m                          Riser: Schedule 40 PVC 1¼ inch diameter
    400
                                                                Joints: glued using purple primer and clear PVC
                                                                cement

    450                                                         Screen: 0.010 slot PVC well screen
                                                                Well developed by hand plunger and bailing to
                                                                remove fines.
    500



                                                              Report Approved by:______________________
                                                                     Department of Ocean Earth and Atmospheric Sciences
                                                                         Old Dominion University, Norfolk, Virginia
                                                                                                                            45


                                            Well Completion Report
Project: Lake Ballard Ancient Creek                         Well Name: 11b
Location: 36.89108N, 76.39969W                              Constructed by Alicia Dobyns, Jennifer MacDonald,
Top of casing elevation: 1.09 m (3.58 ft)                   Nathan Rycroft, Gretchen Teed, Dr. Rich Whittecar
                                                            Construction Date: 06/12/08
Scale (cm)          Borehole Information                             Well Construction Information



                                                                                       Above ground riser of 37 cm

     0              0-10 cm: mud & roots (initial hole)

                                                                                     Bentonite

     50             10-70 cm: gray sand


                    70-125 cm: sand grading into gray mud                            Filter pack of medium sand
    100             with organic matter



    150



    200



    250



    300



    350


                 Hand augered to 1.25 m                            Riser: Schedule 40 PVC 1¼ inch diameter
    400
                                                                  Joints: glued using purple primer and clear PVC
                                                                  cement

    450                                                           Screen: 0.010 slot PVC well screen
                                                                  Well developed by hand plunger and bailing to
                                                                  remove fines.
    500



                                                                Report Approved by:______________________
                                                                       Department of Ocean Earth and Atmospheric Sciences
                                                                           Old Dominion University, Norfolk, Virginia
                                                                                                                             46



                                             Well Completion Report
Project: Lake Ballard Ancient Creek                          Well Name: 11c – VC1
Location: 36.89108N, 76.39969W                               Constructed by Alicia Dobyns, Jennifer MacDonald,
Top of casing elevation: 1.13 m (3.70 ft)                    Nathan Rycroft, Gretchen Teed, Dr. Rich Whittecar
                                                             Construction Date: 06/12/08
Scale (cm)           Borehole Information                             Well Construction Information



            Depths of pore water samples from VC 1                                      Above ground riser of 40 cm

     0               0-10 cm: mud & roots (initial hole)



     50              10-70 cm: gray sand

                                                                                      Sandy cuttings

    100              70-140 cm: sand grading into gray mud
                     with organic matter


    150

                                                                                      Bentonite

    200
                     140-260 cm: black mud with fibrous
                     organic matter

    250

                                                                                      Filter pack of medium sand

    300


                     260-360 cm: gray mud with sand and
    350              roots



                 Hand augered to 3.6 m                              Riser: Schedule 40 PVC 1¼ inch diameter
    400
                                                                   Joints: glued using purple primer and clear PVC
                                                                   cement

    450                                                            Screen: 0.010 slot PVC well screen
                                                                   Well developed by hand plunger and bailing to
                                                                   remove fines.
    500



                                                                 Report Approved by:______________________
                                                                        Department of Ocean Earth and Atmospheric Sciences
                                                                            Old Dominion University, Norfolk, Virginia
                                                                                                                          47


                                             Well Completion Report
Project: Lake Ballard Ancient Creek                       Well Name: 12a
Location: 36.89114N, 76.39971W                            Constructed by Alicia Dobyns, Jennifer MacDonald,
Top of casing elevation: 1.34 m (4.39 ft)                 Nathan Rycroft, Gretchen Teed, Dr. Rich Whittecar
                                                          Construction Date: 06/12/08
Scale (cm)           Borehole Information                          Well Construction Information



                                                                                     Above ground riser of 25 cm

     0               0-76 cm: muddy sand (initial hole)

                                                                                   Bentonite

     50


                     76-86 cm: gray & black sand
                                                                                   Filter pack of medium sand
    100              86-110 cm: finely bedded sand
                     mud lamination


    150



    200



    250



    300



    350


                                                                 Riser: Schedule 40 PVC 1¼ inch diameter
    400
                                                                Joints: glued using purple primer and clear PVC
                                                                cement
                 Hand augered to 1.10 m
    450                                                         Screen: 0.010 slot PVC well screen
                                                                Well developed by hand plunger and bailing to
                                                                remove fines.
    500



                                                              Report Approved by:______________________
                                                                     Department of Ocean Earth and Atmospheric Sciences
                                                                         Old Dominion University, Norfolk, Virginia
                                                                                                                              48


                                             Well Completion Report
Project: Lake Ballard Ancient Creek                          Well Name: 12b – VC2
Location: 36.89114N, 76.39971W                               Constructed by Alicia Dobyns, Jennifer MacDonald,
Top of casing elevation: 1.55 m (5.07 ft)                    Nathan Rycroft, Gretchen Teed, Dr. Rich Whittecar
                                                             Construction Date: 06/12/08
Scale (cm)           Borehole Information                              Well Construction Information



            Depths of pore water samples from VC2                                        Above ground riser of 25 cm

     0               0-76 cm: muddy sand (initial hole)
                                                                                         Bentonite


     50


                     76-86 cm: gray & black sand
    100              86-116 cm: finely bedded sand
                     mud lamination
                     116-146 cm: mud with trace amounts of                               Filter pack of medium sand

    150              fibrous organic matter
                     146-156 cm: sand & mud with organic matter


    200
                      156-366 cm: mud with fibrous organic                               Bentonite
                      matter

    250


                                                                                          Filter pack of medium sand
    300



    350

                   366-375 cm: gray mud and sand
                                                                    Riser: Schedule 40 PVC 1¼ inch diameter
    400
                                                                    Joints: glued using purple primer and clear PVC
                                                                    cement
                 Hand augered to 3.75 m
    450                                                             Screen: 0.010 slot PVC Johnson well screen
                                                                    Well developed by hand plunger and bailing to
                                                                    remove fines.
    500



                                                                  Report Approved by:______________________
                                                                         Department of Ocean Earth and Atmospheric Sciences
                                                                             Old Dominion University, Norfolk, Virginia
                                                                                                                            49


                                              Well Completion Report
Project: Lake Ballard Ancient Creek                         Well Name: 13 – VC3
Location: 36.89130N, 76.39964W                              Constructed by Preston Lewis, Heather Moore,
Top of casing elevation: 1.62 m (5.31 ft)                   Gretchen Teed, Kellie Wright, Dr. Rich Whittecar
                                                            Construction Date: 06/16/08
Scale (cm)           Borehole Information                            Well Construction Information



            Depths of pore water samples from VC3                                      Above ground riser of 27 cm

     0               0-120 cm: sands (initial hole)
                                                                                     Bentonite


     50



    100



    150              120-203 cm: finely bedded mud & sand
                     with organic matter                                             Filter pack of medium sand


    200



    250



    300



    350


                 Hand augered to 2.03 m                            Riser: Schedule 40 PVC 1¼ inch diameter
    400
                                                                  Joints: glued using purple primer and clear PVC
                                                                  cement

    450                                                           Screen: 0.010 slot PVC well screen
                                                                  Well developed by hand plunger and bailing to
                                                                  remove fines.
    500



                                                                Report Approved by:______________________
                                                                       Department of Ocean Earth and Atmospheric Sciences
                                                                           Old Dominion University, Norfolk, Virginia
                                                                                                                              50


                                            Well Completion Report
Project: Lake Ballard Ancient Creek                           Well Name: 14a
Location: 36.891389N, 76.399236W                              Constructed by Preston Lewis, Heather Moore,
Top of casing elevation: 2.00 m (6.56 ft)                     Gretchen Teed, Kellie Wright, Dr. Rich Whittecar
                                                              Construction Date: 06/16/08
Scale (cm)          Borehole Information                               Well Construction Information



                                                                                         Above ground riser of 38 cm

     0              0-107 cm: very compacted silty sand
                                                                                       Bentonite


     50

                                                                                       Sandy cuttings

    100                                                                                Bentonite
                    107-137 cm: cleaner tan sand grading to
                    gray sand

    150
                    137-168 cm: clay with organic matter

                                                                                       Filter pack of medium sand
    200             168-205 cm: clay grading to gray sand




    250



    300



    350


                 Hand augered to 2.05 m                              Riser: Schedule 40 PVC 1¼ inch diameter
    400
                                                                    Joints: glued using purple primer and clear PVC
                                                                    cement

    450                                                             Screen: 0.010 slot PVC well screen
                                                                    Well developed by hand plunger and bailing to
                                                                    remove fines.
    500



                                                                  Report Approved by:______________________
                                                                         Department of Ocean Earth and Atmospheric Sciences
                                                                             Old Dominion University, Norfolk, Virginia
                                                                                                                                 51


                                            Well Completion Report
Project: Lake Ballard Ancient Creek                              Well Name: 14b
Location: 36.891389N, 76.399236W                                 Constructed by Preston Lewis, Heather Moore,
Top of casing elevation: 2.08 m (6.83 ft)                        Gretchen Teed, Kellie Wright, Dr. Rich Whittecar
                                                                 Construction Date: 06/16/08
Scale (cm)          Borehole Information                                  Well Construction Information



                                                                                            Above ground riser of 46 cm

     0              0-137 cm: sandy fill with clean sand at
                                                                                          Bentonite
                    bottom


     50

                                                                                          Sandy cuttings

    100



    150



    200
                    137-274 cm: silt/sand with lots of organic
                    chunks, roots, fibers

    250
                                                                                          Bentonite


    300
                                                                                          Filter pack of medium sand

                      274-351 cm: fine grey clean sand
    350


                 Hand augered to 3.51 m                                 Riser: Schedule 40 PVC 1¼ inch diameter
    400
                                                                       Joints: glued using purple primer and clear PVC
                                                                       cement

    450                                                                Screen: 0.010 slot PVC well screen
                                                                       Well developed by hand plunger and bailing to
                                                                       remove fines.
    500



                                                                     Report Approved by:______________________
                                                                            Department of Ocean Earth and Atmospheric Sciences
                                                                                Old Dominion University, Norfolk, Virginia
                                                                                                                                52


                                              Well Completion Report
Project: Lake Ballard Ancient Creek                             Well Name: 15 – VC4
Location: 36.89158N, 76.39942W                                  Constructed by Preston Lewis, Heather Moore,
Top of casing elevation: 1.04 m (3.42 ft)                       Gretchen Teed, Kellie Wright, Dr. Rich Whittecar
                                                                Construction Date: 06/16/08
Scale (cm)          Borehole Information                                 Well Construction Information



                                                                                           Above ground riser of 39 cm

     0              0-91 cm: construction fill (initial hole)
                                                                                         Bentonite


     50

                                                                                         Sandy cuttings

    100             91-121 cm: medium to fine grained
                    orange/yellow sand


    150             121-171 cm: medium to fine yellow sand                               Bentonite
                    with black spots
                    171-173 cm: mud lens
                    173-193 cm: medium to fine sand with                                 Filter pack of medium sand
    200             black spots

                    193-221 cm: coarse sand yellow grading to tan

    250



    300



    350


                 Hand augered to 2.21 m                                Riser: Schedule 40 PVC 1¼ inch diameter
    400
                                                                      Joints: glued using purple primer and clear PVC
                                                                      cement

    450                                                               Screen: 0.010 slot PVC well screen
                                                                      Well developed by hand plunger and bailing to
                                                                      remove fines.
    500



                                                                    Report Approved by:______________________
                                                                           Department of Ocean Earth and Atmospheric Sciences
                                                                               Old Dominion University, Norfolk, Virginia
                                                                                                 53


        Appendix B: Sediment Analysis Reports
          Vibracore 1: Sediment Analysis Results


Description based on visual inspection
                                                                            2.486     1.383
                                                                                        1.698
                                                           15.579                          0.980




                                          9.225



                                                                                                          41.589




                                                   21.810




                                                                    0.419
                                                                                      11.778
                                                  15.456




                                                                                                  9.777

                                          6.890


                                                                                               0.931

                                                  5.773

                                                                             16.155
                                                                                              54


          Vibracore 2: Sediment Analysis Results

Description based on visual inspection                                0.682      0.641
                                                              0.125

                                                                                          1.058
                                                                                                   5.919




                                         20.716




                                                                                                   9.665




                                                                              3.370




                                                                       2.235

                                                  15.166                                  9.447




                                                                                                   6.239



                                                                                                   0.951
                                         8.827




                                                      6.482                              16.925
                                                                                                    55


                     Vibracore 3: Sediment Analysis Results



                                                                                       8.842


                                                                                                 7.967
Description based on visual inspection           30.007

                                                                                                   6.435


                                                                                                 6.347

                                                          5.253                         9.849
                                                                   4.771
                                                                     3.937 0.140
                                                                                   1.850 4.259
                                                                  1.597

                                                      10.284
                                                                                                   13.227




                                                                          59.997
                                                                                                      56


                   Well 14 Sediment Analysis Results


Description based on visual inspection
                                                                       1.235
                                                               0.797
                                                            1.328
                                                       6.467            3.067

                                             6.108



                                                                                            27.141




                                              53.857




                                                                       0.908
                                                                                0.928

                                                                                   1.197

                                                                                           2.517




                                                                                                   7.737


                                           22.385



                                                                                             2.125

                                                                                        1.032
                                                                                              57


                Vibracore 4: Sediment Analysis Results
                                                                    2.809        2.679
                                                            2.312        0.605
                                                                                      2.571
Description based on visual inspection                  6.569                             3.522




                                                                           73.099




                                                                      0.621   6.337
                                                         12.177
                                                                                          8.834




                                               12.078                                             7.741




                                                                                                  16.153




                                                        31.710
                                                                                 58


                                   Appendix C: Tables

Table I – YSI data collected from Lake Ballard

                                         June 2, 2008

                        Lake Ballard - Station 1 - N 36.89250 W 76.40062
                   Depth from                                         D. O.
                   Surface (m)     Temp ( C )       Salinity (ppt)   (mg/L)
                               -1            25.7               2.8        8.1
                               -2            25.5               2.8        8.5
                               -3            24.2               2.8        7.9
                               -4            22.1               2.8        9.8
                               -5            17.1               2.8       10.4
                               -6            12.1               2.8       10.6
                               -7            10.2               2.9        0.4
                               -8             9.3               2.8          0



                      Lake Ballard - Station 2 - N 36.89236 W 76.39981
                     Depth from                                     D. O.
                     Surface (m)     Temp ( C ) Salinity (ppt)     (mg/L)
                                 -1         25.7            2.9         8.3
                                 -2         25.5            2.9         8.9
                                 -3         24.3            2.8         8.8
                                 -4         21.9            2.8         8.5
                                 -5         16.8            2.8        11.2
                                 -6         12.4            2.8        10.6
                                 -7         10.3            2.8        0.13
                                 -8           9.1           2.8           0
                                 -9           8.6           2.9           0
                               -10            8.3           2.9           0
                               -11            8.3           3.1           0
                               -12            8.7           5.7           0
                               -13            9.1           6.3           0
                                                       59


 Lake Ballard - Station 3 - N 36.89223 W 76.39972
 Depth from                     Salinity    D. O.
 Surface (m)     Temp ( C )      (ppt)     (mg/L)
            -1          25.1         2.9          8
            -2            25         2.9        8.9
            -3            24         2.8        8.3
            -4          22.1         2.8        8.7
            -5            17         2.8       10.8
            -6          12.3         2.7       10.5
          -6.5          10.7         2.9        2.6
            -7            10         2.8       0.11
            -8             9         2.9          0
            -9           8.5         2.9          0
           -10           8.2         2.9          0
           -11           8.3         3.1          0
        -11.5            8.5         3.2          0
           -12           8.7         5.6          0
        -12.5            8.9         6.1          0



 Lake Ballard - Station 4 - N 36.89295 W 76.40158
Depth from                     Salinity     D. O.
Surface (m)     Temp (C)         (ppt)     (mg/L)
          -1          26.9             2.8      8.3
          -2          25.9             2.8      9.6
          -3          24.5             2.8      8.7
          -4          23.8             2.8      3.8



 Lake Ballard - Station 5 - N 36.89287 W 76.40068
Depth from                      Salinity     D. O.
Surface (m)     Temp ( C )       (ppt)      (mg/L)
          -1           26.6            2.9       8.8
          -2           25.7            2.8       9.5
          -3             24            2.8       9.3
          -4           22.2            2.8       9.5
          -5           16.6            2.8      10.4
          -6           12.8            2.8       9.8
                                                                                                      60


                           Lake Ballard - Station 6 - N 36.89297 W 76.40015

                        Depth from
                        Surface (m)      Temp ( C )    Salinity (ppt)    D. O. (mg/L)
                                 -1           26.9                2.8             8.8
                                 -2           25.4                2.8             9.2
                                 -3           24.1                2.8               9
                                 -4           22.4                2.8             9.7
                                 -5           16.7                2.8            11.7
                                 -6           12.8                2.9            11.4
                               -6.5           10.5                2.9            0.79
                                 -7             9.9               2.9             0.2
                                 -8               9               2.9               0
                                 -9             8.5               2.9               0
                                -10             8.2               2.9               0
                                -11             8.3                 3               0
                                -12             8.6               5.5               0



Table II – Alkalinity data for Lake Ballard (blank for dropped or no runs)

                           Lake Ballard - Station 3 - N 36.89223 W 76.39972
                                                                                         Alkalinity
                                                               Alk.        Alkalinity      (meq)
           Depth    Alkalinity   Alkalinity    Alkalinity    Average      (meq) Std.      Average
            (m)     (meq) 1      (meq) 2        (meq)3        (meq)          Dev          Std. Dev
              2       1.9171       1.8996         1.9112       1.9093    0.00890337     0.00726957
              4       2.0342       1.9454         1.9430       1.9742    0.05197538     0.04243772
              6       1.9098       1.9122         1.9155       1.9125    0.00286182     0.00233666
              7                    2.0350         2.0027       2.0189    0.02283955         0.01615
              9       2.0080       1.9402         2.0262       1.9915    0.04532122     0.03700462
             10       2.1988       2.2051                      2.2020    0.00445477         0.00315
             11       2.5849                     2.5874        2.5862    0.00176777         0.00125
             12       5.5487                     5.7264        5.6376    0.12565288         0.08885



                           Lake Ballard - Station 6 - N 36.89297 W 76.40015
                                                                                         Alkalinity
                                                                Alk.       Alkalinity      (meq)
          Depth    Alkalinity    Alkalinity   Alkalinity     Average       (meg)Std       Average
           (m)     (meq) 1       (meq) 2       (meq)3         (meq)        Deviation      Std. Dev
             2       1.9322        2.0072        1.9312     1.9568667     0.04359281    0.03559338
             4       1.9509        1.9456                      1.94825    0.00374767        0.00265
             6       1.8821        1.9012       1.9146          1.8993     0.0163331    0.01333592
             7       2.0059        2.0403                       2.0231    0.02432447         0.0172
             9       1.7136        2.1613       2.1563          2.0104     0.2570485    0.20987922
            10       2.1961        2.1938                      2.19495    0.00162635        0.00115
            11       2.9037        2.8907                       2.8972    0.00919239         0.0065
            12      11.6594       11.6762                      11.6678    0.01187939         0.0084
                                                                                               61


                                   Table III – Well Data

                                           YSI

     Well Data 6/23/2008                           Well Data 7/14/2008

                              Dissolved                                           Dissolved
          Temp     Salinity    Oxygen                    Temp        Salinity      Oxygen
Well #     °C        ppt        mg/L          Well #      °C           ppt          mg/L
      1     19.9        2.2        0.09             1      20.7           2.4          0.08
      2                                             2
      7     20.0       2.8         0.38             7         17.1          3.1         0.00
      8     19.9       2.5         0.28             8         17.6          2.9         0.23
      3     20.1       0.8         0.00          11a          23.0         10.0         0.15
      5     17.0       0.5         0.00          11b          21.5          8.8         0.06
      6     16.3       1.4         0.00          11c          16.6          2.9         0.13
   11a      21.9       0.3         6.48          12a          21.3          6.5         0.10
   11b      22.2       0.0         1.85          12b    n/a          n/a          n/a
   11c      15.9       5.1         0.00          13a          19.5          2.7         0.03
   12a      20.0       7.2         0.01          14a          20.1          3.3         0.31
   12b      20.2       3.5         0.07          14b          16.9          2.2         0.26
   13a      17.9       2.4         0.01            15         21.2          1.5         0.16
   14a      19.4       2.9         0.31        Creek          27.0         25.0         4.70
   14b      18.3       2.2         0.59         Lake          29.5          2.9         7.50
     15     23.2       1.0         0.29
 Creek      26.3      18.6         6.48
  Lake      28.9       2.9         5.25
                                                                                                          62


                                            Head Data

                        Well Data 6/23/2008
                               Depth
                                 to
           Top of              Water                           Bottom      Amt of
           Casing    TOC in    (DTW)       Head      Head      Depth       H2O in
Well #    (TOC) ft     m          ft         ft      in m         ft         ft        Notes:
      1       7.64     2.33        6.68      0.96      0.29        9.51       2.83     Lake rod reading 12.06 ft
      2       8.63     2.63          dry       <1                  7.61         dry    Lake elevation 1.17 ft
      7      11.09     3.38      10.18       0.91      0.28      40.99      30.81        (0.36 m)
      8      10.37     3.16        9.48      0.89      0.27      26.31      16.83      Based on tide data from
      3       7.75     2.36        8.18     -0.43     -0.13      10.85        2.67     6/23/08 @ Old Pt. Comfort
      5      10.21     3.11      10.56      -0.35     -0.11      17.54        6.98     (2.2 ft @ time of data)
      6       9.60     2.93        9.85     -0.25     -0.08      50.30      40.45
   11a        3.49     1.06        2.88      0.61      0.19        3.70       0.82     Creek rod reading 11.03 ft
   11b        3.58     1.09        2.66      0.92      0.28        5.51       2.85
   11c        3.70     1.13        3.82     -0.12     -0.04      11.58        7.76
   12a        4.39     1.34        3.77      0.62      0.19        5.55       1.78
   12b        5.07     1.55        4.54      0.53      0.16      14.83      10.29
   13a        5.31     1.62        5.11      0.20      0.06        6.66       1.55
   14a        6.56     2.00      6.265       0.30      0.09        6.73     0.465
   14b        6.83     2.08        6.46      0.37      0.11      11.49        5.03
     15       3.42     1.04        2.08      1.34      0.41        7.29       5.21



                         Well Data 7/07/2008
                                Depth
           Top of                 to
           Casing               Water                           Bottom       Amt of
          (TOC) ft   TOC in     (DTW)       Head      Head      Depth ft     H2O in
Well #      6/23       m          ft         ft       in m       (6/23)        ft              Notes:
   11a        3.49      1.06       1.37      2.12       0.65        3.70        2.33           DTW taken after several
   11b        3.58      1.09       1.45      2.13       0.65        5.51        4.06                days of heavy rain
   11c        3.70      1.13       3.08      0.62       0.19       11.58        8.50           Metric conversion by

   12a        4.39      1.34        2.49      1.90      0.58        5.55        3.06           OnlineConversion.com
   12b        5.07      1.55        4.66      0.41      0.12       14.83       10.17           Plunger dropped in 12b
   13a        5.31      1.62        5.11      0.20      0.06        6.66        1.55
   14a        6.56      2.00        6.31      0.25      0.08        6.73        0.42
   14b        6.83      2.08        6.55      0.28      0.09       11.49        4.94
    15        3.42      1.04        1.97      1.45      0.44        7.29        5.32
                                                                                                63


                        Well Data 7/10/2008
                              Depth
          Top of                to
          Casing              Water                          Bottom      Amt of
          (TOC)      TOC in   (DTW)       Head      Head      Depth      H2O in
Well #    ft 6/23      m         ft        ft       in m     ft (6/23)     ft
      1       7.64     2.33       6.87     0.77       0.23        9.51      2.64
      2       8.63     2.63         dry       <1                  7.61
      7     11.09      3.38     10.34      0.75      0.23        40.99     30.65
      8     10.37      3.16       9.35     1.02      0.31        26.31     16.96
      3       7.75     2.36         n/s                          10.85
      5     10.21      3.11       7.46      2.75      0.84       17.54     10.08
      6       9.60     2.93     10.21      -0.61     -0.19       50.30     40.09
   11a        3.49     1.06       1.31      2.18      0.66        3.70      2.39
   11b        3.58     1.09       1.42      2.16      0.66        5.51      4.09
   11c        3.70     1.13       7.01     -3.31     -1.01       11.58      4.57
   12a        4.39     1.34       1.72      2.67      0.81        5.55      3.83
   12b        5.07     1.55       4.49      0.58      0.18       14.83     10.34
   13a        5.31     1.62       4.83      0.48      0.15        6.66      1.83
   14a        6.56     2.00       6.17      0.39      0.12        6.73      0.56
   14b        6.83     2.08       6.44      0.39      0.12       11.49      5.05
     15       3.42     1.04       2.12      1.30       0.4        7.29      5.17



                        Well Data 7/14/2008
                              Depth
          Top of                to
          Casing              Water                          Bottom      Amt of
          (TOC)      TOC in   (DTW)       Head      Head      Depth      H2O in
Well #       ft        m         ft         ft      in m     ft (6/23)     ft       Notes:
      1       7.64     2.33       6.99      0.65      0.20        9.51      2.52    No rain over weekend
      2       8.63     2.63         dry        <1                 7.61        dry
      7     11.09      3.38     10.63       0.46      0.14       40.99    30.36
      8     10.37      3.16       9.69      0.68      0.21       26.31    16.62
   11a        3.49     1.06       2.38      1.11      0.34        3.70      1.32
   11b        3.58     1.09       2.51      1.07      0.33        5.51          3
   11c        3.70     1.13       5.02     -1.32     -0.40       11.58      6.56
   12a        4.39     1.34       2.75      1.64      0.50        5.55        2.8
   12b        5.07     1.55       4.36      0.71      0.22       14.83    10.47
   13a        5.31     1.62       4.87      0.44      0.13        6.66      1.79
   14a        6.56     2.00       6.22      0.34      0.10        6.73      0.51
   14b        6.83     2.08       6.41      0.42      0.13       11.49      5.08
     15       3.42     1.04       2.18      1.24      0.38        7.29      5.11
                                                                                                   64


                                 Table IV – Pore Water Salinity Data

            VCI                                  VC2                                    VC3
Depth        mid     Salinity                      mid     Salinity                       mid      Salinity
 (m)        depth     (ppt)          Depth (m)    depth     (ppt)          Depth (m)     depth      (ppt)
        0                                    0                                      0
                                                                                                   No
   0.1                                     0.1                                    0.1              data
   0.2                                     0.2      0.15         7                0.2
   0.3        0.25        13               0.3                                    0.3
   0.4                                     0.4                                    0.4      0.35            5
   0.5                                     0.5                                    0.5
   0.6                                     0.6                                    0.6
   0.7                                     0.7      0.65         6                0.7
   0.8                                     0.8                                    0.8
   0.9        0.85        10               0.9                                    0.9
     1                                       1      0.85         5                  1      0.95            2
   1.1                                     1.1                                    1.1
   1.2                                     1.2      1.15       3.5                1.2
   1.3        1.25         5               1.3                                    1.3
   1.4                                     1.4                                    1.4
   1.5        1.45       4.5               1.5                                    1.5
   1.6                                     1.6                                    1.6      1.55            0
   1.7                                     1.7                                    1.7
   1.8                                     1.8                                    1.8
   1.9        1.85         2               1.9                                    1.9
     2                                       2                                      2
   2.1                                     2.1      2.05         2                2.1
   2.2                                     2.2                                    2.2      2.15           0.5
   2.3        2.25         1               2.3                                    2.3
   2.4                                     2.4                                    2.4
   2.5                                     2.5                                    2.5
   2.6                                     2.6                                    2.6
   2.7                                     2.7                                    2.7
   2.8        2.75         2               2.8                                    2.8
   2.9                                     2.9                                    2.9
     3                                       3                                      3
   3.1                                     3.1      3.05       0.5                3.1
   3.2                                     3.2                                    3.2
   3.3                                     3.3                                    3.3
   3.4                                     3.4                                    3.4
        No data was recovered from VC4 due to the absence of pore water in the sediment samples.
                                                                                65


                        Table V – Ion Chromatograph Data

                                 Lake Data

          June 2, 2008                                  June 2, 2008
         June 16, 2008                                 June 16, 2008
             Depth     Sulfate                             Depth     Chloride
Station       (m)       (mM)                 Station        (m)       (mM)
Station 3      2         1.43                Station 3       2        42.48
    3          4         1.44                    3           4        41.69
    3          6         1.40                    3           6        43.11
    3          7         1.42                    3           7        42.69
    3          9         1.44                    3           9        43.19
    3          10        1.43                    3           10       43.33
    3          11        1.31                    3           11       46.41
    3          12        1.09                    3           12       58.20
Station 6      2         1.38                Station 6       2        39.53
    6          4         1.44                    6           4        40.76
    6          6         1.45                    6           6        40.98
    6          7         1.44                    6           7        43.90
    6          9         1.44                    6           9        45.10
    6          10        1.43                    6           10       45.63
    6          11        1.40                    6           11       50.02
    6          12        0.88                    6           12       80.64



                  Well Data                          Well Data

               June 23, 2008                       June 23, 2008
               June 30, 2008                       June 30, 2008
                      Chloride                             Sulfate
            Well #      (mM)                    Well #      (mM)
               1        39.54                      1         0.60
               3           -                       3         0.19
               6        17.85                      6         1.36
               7        41.68                      7         1.35
               8        41.37                      8         1.10
              10         1.04                     10         0.03
             11A       157.48                    11A         0.11
             11B       113.22                    11B         0.26
             11C       129.07                    11C         2.00
             12A       100.77                    12A         0.17
             12B         2.00                    12B         0.32
             13A        44.80                    13A         0.57
             14A        40.30                    14A         1.56
             14B        30.02                    14B         1.24
              15        12.06                     15         0.25
                                              66

    Core Data              Core Data

    June 2, 2008           June 2, 2008
   June 26, 2008          June 26, 2008
            Chloride                Sulfate
Sample       (mM)      Sample        (mM)
  VC-1        24.83      VC-1         4.52
 VC-3A        62.41     VC-3A         0.34
 VC-3C       100.16     VC-3C         6.79
 VC-4A        29.72     VC-4A         1.83
 VC-6A       128.38     VC-8A       230.66
 VC-6B        73.32    VC-11A       103.67
 VC-8A       136.31     VC-14        16.54
 VC-8B       165.04     VC-15         4.63
VC-11A        24.66     VC-16       385.09
VC-11B        13.84     VC-24         0.90
 VC-14        83.02
 VC-15        39.23
 VC-16       141.04
 VC-18        20.12
 VC-22        37.89
 VC-24        24.83
                                                                                                67


                                          References

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       application of various field data collection and GIS techniques.” Unpublished report. Old

       Dominion University, Norfolk, Virginia, 9 pgs.

Alexander, B., Jones, C., Schweitzer, C., Taylor, S., & Williams, J. (2007). “The sources of

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       report. Old Dominion University, Norfolk, Virginia, 63 pgs.

Austin, D. D. (2005). “A comprehensive physical and chemical study of Lake Ballard, a brackish

       water lake in Portsmouth, Virginia.” Unpublished M.S. thesis, Christopher Newport

        University, Newport News, Virginia, 67 pgs.

Dionex Corporation. (2002). Principles and Troubleshooting Techniques in ION

       CHROMATOGRAPHY.

Google Earth [computer software]. (2008). Available from http: www.google.com

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The Weather Channel. Portsmouth rainfall data [Data file]. Retrieved from

       http://www.weather.com

Tides and Currents. (July, 2008). National Oceanic and Atmospheric Association.

       Retrieved July 28, 2008, from http://tidesandcurrents.noaa.gov/index.shtml.

Whittecar, G. R., Nowroozi, A. A., & Hall, J. R. (2005). Delineation of saltwater intrusion

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        Geoscience, XI(3), 209-219.
                                                                                 68


Wolny, J. L. (1999). A study of the seasonal composition and abundance of

       phytoplankton and autotrophic picoplankton in a brackish water lake,

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       Norfolk, Virginia, 54 pgs.

				
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