WQ0003271_Comprehensive Site Assessment Work Plan_20241023

kimley-horn.com 600 North Pine Island Road | Suite 450, Plantation, FL 33324 954 535 5100

October 23, 2024
Nathaniel Thornburg
North Carolina Department of Environmental Quality
Division of Water Resources – Non-Discharge Branch
1617 Mail Service Center
Raleigh, NC 27699-1617

RE: Comprehensive Site Assessment Work Plan
Hestron Park Wastewater Treatment Plant Permit No. WQ0003271
Carteret County, North Carolina

Dear Mr. Thornburg:

Kimley-Horn and Associates, Inc. (Kimey-Horn) has prepared the following Comprehensive Site
Assessment Work Plan on behalf of Carolina Water Services, Inc. (Carolina Water) for their Hestron
Park Wastewater Treatment Plant (WWTP). This Work Plan was prepared in response to the
Department’s September 14, 2023 correspondence regarding the facility which Kimley-Horn discussed
during our August 2, 2024 meeting with the Department.
Project Understanding

Pursuant to the Department’s September 14, 2023 correspondence, Carolina Water is required to
complete a Comprehensive Site Assessment for the Hestron Park facility to address the cause,
significance, and extent of the groundwater contamination observed during recent sampling at the
WWTP. Concentrations of chloride, total dissolved solids, and total nitrate as nitrogen have been
reported in the groundwater above the maximum contaminant levels (MCL). The purpose of the
Comprehensive Site Assessment is to determine whether the operation of the facility’s high-rate
infiltration system has contributed to the localized groundwater impacts.
WORK PLAN

The following Work Plan has been prepared in general accordance with 15A NCAC 02L .0106. The
assessment activities will consist of soil and groundwater screening. Pending the results of the
groundwater screening, permenant groundwater monitoring wells will be installed on-site to
characterize the extend of the groundwater contamination and verify the hydraulic parameters of the
surficial aquifer.
Groundwater Screening

Kimley-Horn will be prepared to collect up to 20 groundwater screening samples as shown in Figure
1. The purpose of the screenings samples is to confirm groundwater quality relative to the contaminants
of concern (COC), which include chloride, total dissolved solids and nitrate. Direct -push technology
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(DPT) will be used to advance up to 20 temporary groundwater screening points in a grid pattern across
the Site. The groundwater screening points will be installed to a nominal depth of 15 feet below land
surface (bls). However, at both shallow and deep groundwater samples will be collected at eight of the
twenty locations, At these eight locations, screening po ints will be advanced to 15 feet bls and 30 feet
bls. The purpose of the deep groundwater samples is to vertically characterize groundwater quality.
Groundwater samples will be collected from each screening point by Kimley -Horn. We will purge the
screening points prior to sampling to facilitate the collection of representative groundwater samples.
Throughout the purging process we will measure and record field parameters including pH,
temperature, specific conductance, turbidity and dissolved oxygen. Kimley -Horn will collect
groundwater samples from each screening point once the field parameters hav e stabilized. We will
collect the samples in laboratory provided and preserved containers. The samples will be placed in an
iced cooler for transport to the designated laboratory under chain-of-custody protocol.
The groundwater screening locations will be abandoned by the drilling contractor following sampling.
The corresponding boreholes will be backfilled with Portland cement or bentonite.
Soil Screening

Kimley-Horn will be prepared to collect soil samples from each of the 20 groundwater screening borings.
Up to two samples will be collected from each location for a total of 40 soil samples. One sample will
be collected at the land surface at 0 to 2-feet bls. The second sample will be collected from the 2-foot
interval immediately above the water table. We will collect the soil samples in laboratory provided and
preserved containers. The samples will be placed in an iced cooler for transport to the designat ed
laboratory under chain-of-custody protocol.
Monitoring Well Installation and Sampling

Kimley-Horn will review the groundwater screening data to determine the location of up to eight
additional permanent monitoring wells that will be used to characterize the extent of the groundwater
impacts. We anticipate that permanent monitoring wells will be installed at the source area or “hot spot”
as well as the up-gradient, down-gradient and side-gradient edged of the contaminant plume.
We will retain a North Carolina Licensed Water Well Contractor to install and develop the proposed
monitoring wells. The monitoring wells will be installed using hollow stem-auger or DPT techniques.
They will be constructed of 2-inch diameter, schedule 40 PVC casing with 10-feet of 0.01-inch machine
slotted well screen. The annular space between the well screen and borehole wall will be backfilled
with clean quartz sand. The monitoring wells will be installed so that the well screen splits the water
table. We anticipated that each well will be completed to a depth of 12 to 15 feet bls, depending on the
static water table elevation at the Site. Each monitoring well will be completed at grade, with a locking
pressure cap and flush-mounted well cover and 2-foot by 2-foot concrete well pad.
The water well contractor will develop the monitoring wells following installation. Development will be
performed to facilitate the removal of silt and sediment that accumulates in the well casing and sand
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pack during installation. Well development will continue until silt and sediment have been removed form
the well and the discharge water is relatively turbid free.
During the drilling of the monitoring wells, the water well contractor will collect continuous lithologic
samples from the land surface to the termination depth of each borehole. The lithology of each
monitoring well will be logged by Kimley-Horn using the Unified Soil Classification System. We will
prepare separate lithologic logs and well construction logs for each proposed monitoring well.
The cuttings will be containerized in 55-gallon drums by the water well contractor. Kimley -Hon will
collect composite soil samples from each drum for characterization purposes. The drums will be staged
on-site on pallets pending the results of the characterization data. Likewise, the development and purge
water from the monitoring wells will also be containerized in 55 -gallons drums. We assume that the
water will be treated by the WWTP. Therefore, we assume characterization will not be required.
Kimley-Horn will collect up to two rounds of groundwater samples from the five existing and eight
proposed monitoring wells. The monitoring wells will be purged and sampled for chloride, total dissolved
solids, total nitrate as nitrogen and ammonia. The two rounds of groundwater samples will be collected
no less than one month apart. Depth to groundwat er measurements will be recorded prior to each
groundwater sampling event. The monitoring wells will be purged by Kimley -Horn prior to sampling to
facilitate collection of representative groundwater samples. We will collect the groundwater samples in
laboratory provided and preserved sample containers. We will retain a NCDEQ certified environmental
laboratory to analyze the groundwater samples collected from th e monitoring wells. Sample analysis
will be performed on a normal 7 to 14-day turnaround time.
Kimley-Horn will retain the services of a Professional Land Surveyor licensed by the State of North
Carolina to survey the northing and easting coordinates, ground surface elevation and top of casing
elevation of the proposed monitoring wells. The elevation data will be used by Kimley-Horn to
normalize the depth to groundwater data and estimate the localized direction of groundwater flow.
Hydraulic Conductivity Testing

Kimley-Horn will conduct hydraulic conductivity testing on up to four of the new and existing monitoring
wells. The slug tests will be performed in accordance with ASTM D4044-96 Standard Test Method for
(Field Procedure) for Instantaneous Change in Head (Slug) Tests for Determining Hydraulic Properties
of Aquifers.
We will analyze the data collected from the slug tests using the software program AquiferWin 32. The
program will allow Kimley-Horn to estimate the hydraulic conductivity of the aquifer pursuant to 15A
NCAC 02L .0111(b). The hydraulic conductivity estimates will be calculated for each monitoring wells
and will be used to estimate an average value for the surficial aquifer at the Site.
Laboratory Analysis

Kimley-Horn will collect the soil and groundwater samples in laboratory provided and preserved
containers. Sample collection will be performed in general acrodance with the NCDEQ’s standard
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operating procedures. Analysis of the smaples will be performed by a laboratory certified by the NCDEQ
and accredited by the NELAC (National Environmental Laboratory Accreditation Conference) Institute.
The soil and groundwater samples will be analyzed for chlorides, total nitrate as nitrogen, and ammonia.
Sample analysis will be performed by the laboratory on a normal 7 to 14 day turnaround time.
Reporting

The results of the soil and groundwater samples will be reported to the NCDEQ in accordance with
the following sections.
Data Summary

Following the initial data collection effort, Kimley -Horn will tabulate and summarize the soil and
groundwater quality data. The data will be compared to the MCLs and state-specific standards. In
addition, we will prepare groundwater contour maps based on the depth to groundwater measurements.
The data summary will also include lithologic and well construction logs. We assume that this initial
data summary will be used for discussion purposes with the Client and NCDEQ. As such, the data will
be marked by Kimley-Horn as “provisional” or “draft”. We assume that final data summaries will be
included with the CSA to be submitted to NCDEQ upon completion of the site assessment activities.
Comprehensive Site Assessment Report
Upon receipt of the laboratory data for the two-rounds of groundwater sampling, Kimley-Horn will
prepare a Comprehensive Site Assessment Report for the facility. The report will be prepared in
accordance with 15A NCAC 02L .0111. The report will include a summary of the sampling
methodologies and interpretation of the corresponding results. Additionally , the report will include, but
is not limited to the following:
• Tabulated summaries of the soil and groundwater quality data
• Maps depicting the soil and groundwater sample locations
• Monitoring well location maps
• Groundwater contours maps
• Hydrostratigraphic cross-sections
• Soil boring logs
• Monitoring well construction logs
• Slug test data and calculations
• Laboratory data sheets.
The report will be signed and sealed by a Professional Geologist licensed in the state of North
Carolina. The report will be submitted to the Department in electronic (PDF) format.

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kimley-horn.com 600 North Pine Island Road, Suite 450, Plantation, FL 33324 954 535 5100

On behalf of Carolina Water Systems, Inc. Kimley-Horn appreciates the Department’s cooperation with
this facility. Please contact Endicott Parks at [phone] or [e-mail]
should you have any questions regarding this work plan.
Respectfully,
KIMLEY-HORN

Endicott Parks Jason C. Sheasley, P.G.
Environmental Analyst Professional Geologist No 2207

Figures:
1 Sample Location Map
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N C H i g h w a y 2 4
24E-003
E-002
E-001
E-004
E-005
15' & 30' BLS 15" BLS 15" BLS 15" BLS 15" BLS
15" BLS 15' & 30' BLS 15" BLS
15" BLS
15' & 30' BLS
15' & 30' BLS
15" BLS
15" BLS 15' & 30' BLS
15' & 30' BLS
15" BLS 15' & 30' BLS 15" BLS 15' & 30' BLS 15" BLS
0 100 20050
Feet
Hestron WWTP
September 2024
Morehead City, NC
¯
¯
Hestron WWTP
Legend
15" BLS
15' & 30' BLS
Existing Observation Wells
Force Main
WWTP Parcel Boundary
Wetlands
Figure 1 - Proposed Soil and Groundwater Screening Locations