DEQ-CFW_00074962

DEQ-CFW 00074962

WESTBROOK ASR PROJECT PLAN
TO REMOVE AQUIFER INJECTED WATER
DRAFT
Cape Fear Public Utility Authority
235 Government Center Drive
Wilmington, North Carolina 28403
August 22, 2017
CATLIN Project No. 217081
Cape fear
Prepared By:
CAT LIN
Engineen; and Scientists
220 Old Dairy Road
Wilmington, NC 28405
[phone]
CORPORATE LICENSURE NO. FOR ENGINEERING SERVICES C-0585
CORPORATE GEOLOGY LICENSE NO. C-118
DEQ-CFW-00074963

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WESTBROOK ASR PROJECT PLAN
TO REMOVE AQUIFER INJECTED WATER
WILMINGTON, NORTH CAROLINA
DRAFT
AUGUST 22, 2017
PREPARED FOR:
CAPE FEAR PUBLIC UTILITY AUTHORITY
235 GOVERNMENT CENTER DRIVE
WILMINGTON, NC 28403
CATLIN PROJECT NO.217081
PREPARED BY:
CATLIN ENGINEERS AND SCIENTISTS
P.O. BOX 10279
WILMINGTON, NORTH CAROLINA 28404-0279
[phone]
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DEQ-CFW 00074964

TABLE OF CONTENTS
PAGE
1.0 INTRODUCTION
1.1 GENX RECOVERY PLAN SUMMARY 1
2.0 AQUIFER PUMPING AND DISCHARGE PLAN 1
2
3.0 GENX PLUME DELINEATION PLAN
2
4.0 SAMPLING PLANS
3
5.0 DATA ANALYSIS PLAN
5
FIGURES
FIGURE 1 WESTBROOKASR PROJECT ALGORITHM TO REMOVE AQUIFER INJECTED
WATER
FIGURE 2 WESTBOOK ASR DISCHARGE ROUTE
FIGURE 3 EXISTING SAMPLING WELL LOCATIONSIDATA AND FOUR PROPOSED NEW
MONITORING WELLS (MW-11, MW-12, MW-13, AND MW-14)
FIGURE 4 MAP OF EXISTING PAST HYDROGEOLOGIC CROS"ECTION A A' AND SOME
FUTURE CROSS -SECTIONS WHEN RECOVERY PUMPING BEGINS
FIGURE 5 CROSS-SECTION OF MONITORING WELLS AND DRAW DOWN LEVELSAFTER
APPROXIMATELY 20 DAYS OF 550 GPM WITHDRAWL FROM ASR-1
(OCTOBER 24, 2016 TO NOVEMBER 12, 2016)
CFPUA; 217081_Praliminary P101mt Plan Draft CATLIN Englnaers and Sclendsts
CATUN ProjaCt No. 217081
August 2017
DEQ-CFW 00074965

DRAFT
WESTBROOK ASR PROJECT PLAN
TO REMOVE AQUIFER INJECTED WATER
WILMINGTON, NORTH CAROLINA
August 22, 2017
1.0 INTRODUCTION
1.1 GENX RECOVERY PLAN SUMMARY
From past cycles of Cape Fear Public Utility Authority (CFPUA) treated water
injection from the Cape Fear River for storage into the upper Peedee aquifer
and past removal of water storage, there is an estimated volume of 48.811
million gallons (MG) of remaining injected water in the upper Peedee aquifer
in the area of Aquifer Storage Recovery Well #1(ASR1). The project plan is
to pump 500 Gallons Per Minute (GPM) from ASR1 until at least 50 MG has
been removed from the aquifer. Based on planned monitoring well sampling
activities and radius of recovery drawdown evaluation, the required removal
plan may exceed the injected, treated water volume.
The first step has been the design and analysis of piping from the ASR1
recovery well to the Northside Waste Water Treatment Plant. The second
step has been to obtain approval to pump the recovered aquifer water to the
sewage treatment system. The discharge has been approved and
construction of the pipeline connection will be underway soon.
Before the recovery begins, sampling of available monitoring wells and
selected deep irrigation wells for GenX is planned. in addition to the existing
sampling wells, four new monitoring wells are planned east, northeast and
southeast of ASR1. All of these wells will be measured for static water levels
and sampled for GenX concentrations. This data will help estimate the radius
of GenX in the upper Peedee aquifer and based on the past drawdown
radius data from previous pump tests, the volume of recoverable water with
GenX concentrations will be estimated and used to determine if an additional
volume above 50 MG needs to be recovered. This total volume divided by
the daily recovery rate from ASR1 will establish the plan for the minimum
Pumping duration as well as monitoring and sampling schedules.
Once the recovery from ASR1 begins, maintenance, monitoring and
sampling will be performed in compliance with the scheduled plan. When the
aquifer recovery plan is complete, data will be assessed to determine if
additional recovery plans are necessary. A summary of data and a report of
completion of the planned volume recovery will be submitted. If additional
CFPt/A; 217081 Piellm/nary Project Plan Draft CATUN Engineers and Scientists
CATUN Project No. NMI �
August 2017
DEQ-CFW 00074966

testing is necessary or more aquifer recovery is required, recommendations
for additional activities will also be submitted to CFPUA. Figure 1 shows the
Westbrook ASR Project Algorithm to Remove Aquifer Injected Water.
2.0 AQUIFER PUMPING AND DISCHARGE PLAN
ASR1 was the well used for past injection and recovery and will now be used for
pumping to recover the last 48.811 MG of injected, treated water. The as -built data
for ASR1 shows that it is 188 feet deep and is screened in the upper Peedee
aquifer from approximately 150 feet to 188 feet. The well is cased and sealed with
bentonite-cement from a depth of 150 feet to the surface level. Past pumping data
shows that ASR1 has been pumped at over 1,028 GPM during a 24-hour test, but
for discharge safety, our plan is to continuously pump ASR1 at 500 GPM.
Our discharge request into the Northside Waste Water Treatment Plant was applied
at a flow of 500 GPM to assure that discharge does not exceed the North Carolina
Department of Environmental Quality (NCDEQ) established limit of 140 Parts Per
Trillion (PPT) of GenX. Recovered aquifer water at ASR1 will be tested every week
to evaluate discharge compliance.
To connect ASR1 to the sewer system, the CFPUA has designed a temporary
pipeline to safely connect to an existing 16" sewage force main pipeline on Military
Cutoff Road. The Westbrook ASR Discharge Route is attached as Figure 2.
Additionally, the discharge pipe design has a Reduced Pressure Zone (RPZ) valve
device near the recovery well and a check valve at the connection to the 16"
pipeline to ensure that if ASR1 is shut down, no sewage can backflow to the well.
Construction of the temporary discharge pipe is estimated to begin in August, 2017
and finish construction to start pumping in September, 2017.
3.0 GENX PLUME DELINEATION PLAN
Prior to starting the ASR1 recovery pump, existing CFPUA monitoring wells
screened in the upper Peedee aquifer will be sampled. Additional plume delineation
data will include the recent samples of the George Page supply well and
Wrightsville Beach water supply well #11 (WB well #11). Based on the GenX
concentrations found in WS well #11 and the lack of monitoring wells between WB
well #11 and ASR1, four new wells are planned to be installed in the near future.
These wells will also be screened in the upper Peedee aquifer and sampled prior to
recovery.
West and northwest of ASR1 are two irrigation wells screened in the upper Peedee
aquifer. The owners have agreed to allow sampling of these irrigation wells. The
map of all existing CFPUA monitoring wells, proposed new monitoring wells, WB
well #11, the George Page private supply well and the two irrigation wells is
CFPUA; 21708i_Preriminary ProJoct Plan Draft CATUN Engineers and Scientists
CA TUN Protect No. 2f7011 2
August 2017
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attached as Figure 3.
The two goals of the pre -aquifer recovery plan for well sampling are to measure the
static water levels for the evaluation of aquifer drawdowns during aquifer recovery
and to determine the GenX concentrations prior to beginning aquifer remediation.
The GenX concentrations will be contoured in order to:
A. Delineate and calculate the area of GenX to determine the volume of water
in the upper Peedee aquifer that needs to be recovered. This volume may
exceed the injected amount of treated water.
B. Based on the estimated radius of GenX that is present in the aquifer, the
sampling plan will be updated. Additional well construction requirements will
also be evaluated.
C. The New Hanover County Health Department has been requested to provide
information of any permitted water supply wells in the area around ASR1.
When these locations and depths are received and the GenX plume
contours have been estimated, we will determine if any more water supply
wells need to be tested during aquifer remediation. We will then contact the
owners and request permission to sample their wells.
4.0 SAMPLING PLANS
Data for the initial GenX plume estimate will be evaluated from the following well
sampling plan:
The depth to static water level will be measured at each monitoring well prior
to sampling. This will also be measured before any future sampling during
recovery pumping to determine aquifer drawdown levels. Static water level in
the irrigation wells and permitted supply wells will unlikely be able to be
measured.
Based on the water level, the well depth and well diameter, a minimum of
three volumes will be purged from the well prior to sampling. To determine
the volume of water to be removed from each monitoring well prior to
sampling, use the following calculations for three volumes to be removed.
2" diameter well = (depth of well - depth to water table) x 0.1633 gal, x 3 = purge gallons
4' diameter well = (depth of well - depth to water table) x o.6531 gal. x 3 = purge gallons
WB 11 10" diameter well = (depth of well - depth to water table) x 4.0816 gat. x 3 = purge gallons
During recovery activities the three volume gallons to be purged will
decrease as drawdown occurs. For the irrigation wells and supply wells to be
sampled that do not have access to measure depth to water level, we will
CFPUA; 2l7081_Prellminary Pm%cf Plan Drag CA TUN Engineers and Scientists
CATLIN Pmject No. 217081 3
August 2017
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assume the static water levels from the pre -pump cross sections to insure
adequate purging. Purged water will be stored in a mobile tank and after
sampling of the well is complete the tank will be discharged safely into a
nearby sewage manhole. The Wrightsville Beach Well #11 purge water will
be pumped to their storage tank.
C. A submersible pump will be necessary to purge and sample monitoring wells
MW-9, MW-10, MWA 1, MW-12, MW-13 and MW-14. The other wells to
sample have existing pumps.
D. Sampling —As previously mentioned, wells will be purged at least three well
volumes of water utilizing a submersible pump and tubing. Once three well
volumes are removed, the wells will be sampled by pumping aquifer water
directly from the well into laboratory provided bottles. For each groundwater
sample collected, three (3) 250 mL plastic bottles will be filled with water
pumped directly from the well. The plastic bottles contain 5 grams/L of
Trizma which serves as a buffering agent to remove free chlorine that may
be present in the sample. The samples will be shipped on ice under proper
chain -of -custody procedures to Eurofins Eaton Analytical, 110 South Hill
Street, South Bend, IN 46617. The samples will be analyzed for the GenX
compound per EPA Method 537 v1.1.
E. A list of the pre -recovery sampling wells and the planned sampling order is
shown below.
) Recently sampled with existing pump
Well
��G..rg-%ge
Recently sampled with existing pump
MW-2
Recently sampled with temporary pump
L ASR1
_
Recently sampled with existing recoverypump
MW-10
Sample with new pump
MW-13
Sample with new pump
MW-14
Sample with new pump
MW-11
Sample with new pump
_ MW-12 _
^
Sample with new pump
MW-9
Sample with new pump
MW-5
Sample with existing pump
MW-7
Sample with existing pump
Irrigation Well —11B
Sample with existing pump
Irrigation Well — 9B
Sample with existing ourrno
F. Based on the initial GenX laboratory data, we will contour the estimated
CFPUA; 217081_Pre/lminary Project plan Draft CATLIN EngJnaers and Scientists
CATLIN PioJQO No. 217081 4 August 2017
DEQ-CFW 00074969

GenX contaminant plume and use this to determine future sampling wells
during and after aquifer recovery pumping. The information that is pending
from the New Hanover County Health Department may also add sampling for
Private supply wells in the plume area.
G. Future drawdown data measurement and GenX sampling after aquifer
recovery begins:
1) When pumping the recovery well foraquifer remediation, ASR1 will be
sampled once per week to evaluate GenX discharge concentrations
to the Northside Wastewater Treatment plant. Each week the water
level transducer will also be recorded.
2) During the first month of aquifer recovery, WB well #11 weekly water
levels will be recorded and this data will be provided by Wrightsville
Beach staff.
3) During the first month of aquifer recovery, all available monitoring
well's depth to water will be measured each week to provide aquifer
drawdown changes, stabilization data and the potential radius of
recovery.
4) If the pre -recovery GenX contour evaluation requires new monitoring
wells, they will be installed during the aquifer recovery pumping as
soon as possible.
5) All wells planned for future sampling will be sampled for GenX at the
end of the first month of aquifer recovery and each following month
during recovery. Depth to water will also be measured in these wells
once per month after the first four weeks of measurements.
6) When pumping of ASR1 has reached the estimated recovery water
volume and has been turned off, selected wells will be measured the
first and second week. The monitoring wells previously tested during
recovery will also be sampled for GenX on the second week.
7) Once all of the above stated measurements and data is obtained, it
will be evaluated to determine if the project can be deemed
"complete" or if additional aquifer recovery is necessary.
5.0 DATA ANALYSIS PLAN
A) Update the recovery and monitoring plan after the initial GenX
concentrations have been evaluated prior to the beginning of aquifer
recovery pumping.
CFPUA; 217091_Pierimrnary Pr%ct Pran_praft CATLIN Engineers and Sclentlsts CATLIN RoJect No. 2170e1 5 August 2017
DEQ-CFW 00074970

1) Map the pre -recovered radius of GenX concentrations.
2) Calculate upper Peedee volumes in the plume radius.
3) Determine necessary volume recovery duration at 500 GPM.
4) Determine the need for additional monitoring wells.
5) Summarize the proposed modified well sampling plan and schedules
for monitoring during aquifer recovery.
Hydrogeologic plan to evaluate aquifer recovery data:
1) Prior to aquifer recovery, prepare hydrogeologic cross -sections from
existing and new monitoring wells with as -built data and pre -recovery
static water levels_
2) When recovery begins, update cross-section drawdown levels from
each well during the first month of pumping at 500 GPM to estimate
the radius of recovery. If the GenX plume exceeds the radius of
recovery, adjust the initial volume recovery duration calculation to the
maximum recovery radius diameter.
3) Update each cross-section after the following monthly measurement
data is obtained to evaluate hydrogeologic stability and possible
impacts from other pumping wells.
4) Figure 4 shows potential cross-section locations.
5) Figure 5 shows the cross-section of A -A'. This cross-section has the
geologic data from the existing ASR monitoring wells and the past
drawdown levels after approximately 20 days of 550 GPM withdrawal
from ASR1, pumped from October 24, 2016 to November 12, 2016.
This cross-section is an example of the other hydrogeologic cross -
sections that will be evaluated when data is obtained before and
during aquifer pumping.
6) After the ASR1 recovery pump is turned off, the plan is to measure
the depth to water table in all monitoring wells the first and second
week after pumping stops to obtain hydrogeology information on the
rate of static water level restoration.
C) GenX Recovery Analysis Plan
The weekly sampling data from the ASR1 recovery well will be
charted to determine GenX concentrations during aquifer drawdown
and concentration changes as recovery continues.
Monthly monitoring well sampling data before, during and after the
planned recovery schedule, will be contoured to determine the areas
CFPUA; 217081_Flip eliminary Project Plan_Draft CATlJN Englnears and Scientits s CATLIN Project No. 217081 8
August 2017
DEQ-CFW 00074971

of GenX concentration changes. This data will be used to determine
recovery success or the need for additional recovery plans. To
evaluate remediation success or additional recovery needs, the future
GenX aquifer concentration environmental standards will continue to
be researched.
D) A summary report of all data will be prepared and submitted to the CFPUA
after the end of this recovery plan. All data, plume contour maps, cross -
sections, lab analysis and measurements will be Included in the report. if
additional remediation is necessary, preliminary remediation/recovery
recommendations will be included in the report.
CC t" 217081_Prepminary Project Plan Draft CATLN Engineers and Scientists
CATf IN Project N0. 217081 7 August 2017
DEQ-CFW 00074972

FIGURES
CFPUA; 217081 Piellm/nary project p/an_prafr CATLIN Engineers and Scientists CATLIN Project No. 217081
August toff
DEQ-CFW 00074973

DEQ-CFW 00074974

DEQ-CFW 00074976

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DEQ-CFW 00074977

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