NC0002374445_20230301_Hemphill Road TCE_RA SWPP Plan for Source Area Remediation

Stormwater Pollution Prevention Plan
Hemphill Road TCE Superfund Site
Remedial Action
Gastonia, North Carolina
Prepared for:

United States Environmental Protection Agency – Region 4
Prepared by:

EQ CH Remediation 1800 Carrillon Blvd. Cincinnati, OH 45240
Remedial Engineering Services (RES) Contract Line Item Number (CLIN) 2 Contract 68HERH19D0009 Task Order Number 68HE0422F0081 DCN RES-R4-22F0081-02003
March 2023
Stormwater Pollution Prevention Plan Remedial Action Hemphill Road TCE Superfund Site Gastonia, North Carolina
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Contents
Acronyms and Abbreviations ..................................................................................................................................... ii
1. Introduction ................................................................................................................................................... 1
1.1 Site Description ................................................................................................................................. 1
1.2 Site History ....................................................................................................................................... 2
1.3 Description of Remedial Activities ................................................................................................... 6
1.4 Post-remedial Activity Conditions .................................................................................................... 7
2. Sources of Pollution ....................................................................................................................................... 7
3. Stormwater Management and Sediment Controls ..................................................................................... 8
3.1 Spill Prevention, Control, and Response ........................................................................................... 8
3.2 Material Storage and Handling ......................................................................................................... 8
3.3 Material Use ...................................................................................................................................... 9
3.4 Vehicle and Equipment Management ............................................................................................... 9
3.5 Decontamination ............................................................................................................................. 10
3.6 Waste Management ......................................................................................................................... 10
3.7 Good Housekeeping ........................................................................................................................ 11
3.8 Preventive Maintenance .................................................................................................................. 11
3.9 Offsite Tracking .............................................................................................................................. 11
4. Erosion Prevention Best Management Practices ...................................................................................... 11
4.1 Protect Vegetation and Minimize Exposed Surfaces ...................................................................... 11
5. References .................................................................................................................................................... 12
Tables
Table 1-1. Site History ................................................................................................................................................... 3 Table 2-1. Construction Site Pollutants ......................................................................................................................... 7
Figures
Figure 1-1. Site Location Figure 1-2. Site Layout
Figure 1-3. Topography
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Acronyms and Abbreviations
Acronym Definition
BMP best management practice
EPA U.S. Environmental Protection Agency
GCEHS Gaston County Environmental Health Services
GIT Gastonia Industrial Truck, Inc.
ISCO in situ chemical oxidation
NCDEM North Carolina Division of Environmental Management
NCDEQ North Carolina Department of Environmental Quality
PSRG Preliminary Soil Remediation Goal
RI remedial investigation
site Hemphill Road TCE Superfund Site, 5009 Hemphill Road,
Gastonia, Gaston County, North Carolina
SWPPP Stormwater Pollution Prevention Plan
TCE trichloroethene
VOC volatile organic compound
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1. Introduction
This Stormwater Pollution Prevention Plan (SWPPP) was prepared under Contract 68HERH19D0009, Task Order Number 68HE0422F0081 for the Hemphill Road TCE Superfund Site located at 5009 Hemphill Road, Gastonia, Gaston County, North Carolina (site). Figures 1-1 and 1-2 depict the location and layout of the site, respectively.
This SWPPP has been prepared and will be implemented in accordance with good engineering practices. Potential sources of pollution are identified that may reasonably be expected to affect the quality of stormwater discharges from the site. Controls and best management practices (BMPs) are identified that will be used to reduce pollutants in stormwater discharges from remedial activities that include well
installation, in situ chemical oxidation (ISCO) injection, and groundwater sampling.
Because there will be less than 1 acre of land disturbance, permit coverage under North Carolina’s General Permit NCG010000 is not required. This SWPPP is not intended to comply with that permit but generally follows its requirements.
1.1 Site Description
The site is in a mixture of residential and commercial/industrial area of South Gastonia and is currently owned and operated by Gastonia Industrial Truck, Inc. (GIT). GIT, located near the center of the property on the developed northwestern parcel, sells and repairs forklifts. Current structures on the GIT property include a metal main facility building and a smaller garage located approximately 150 feet south of the main facility building. A concrete pad and a loading dock are on the northern side of the main facility building. The loading dock and concrete pad stored equipment and miscellaneous parts. The land around
the GIT buildings consists of either a gravel driveway/parking lot or a grass field that was used in the forklift repair operations. Some junked automobiles and a dilapidated semi-trailer are present that the property owner uses as storage. The wooded areas onsite generally consist of hardwood trees and dense to
moderately dense underbrush (for example, brambles). Fallen trees, tree limbs, and leaf matter cover the floor of the wooded areas.
The site is bordered on the northwest by an unnamed tributary, on the west by Hemphill Road, and to the
northeast, east, and south by private/residential property. Two individual residences and the Kensington Estates subdivision are southwest of the site directly across Hemphill Road. Kensington Estates contains approximately 60 housing units. Wesley Acres is toward the southwest along Forbes Road. The Wesley Acres community potable water well serves approximately 66 homes. Several other residences are located along Hemphill Road, and several additional subdivisions, mobile home communities, and individual homes are within a 0.5-mile radius of the site (Versar, 2020).
Surface drainage at the site is generally to the northwest. Surface water features onsite include an unnamed tributary along the northern border that flows northeast to southwest and a small unnamed pond located just north of the northeastern boundary (Figure 1-3). There are also two natural drainageways that drain northwestward to the unnamed tributary. One drainageway is located on the western portion of the site, and the other is located west of the site between the private residences along Hemphill Road and the
Kensington Estates subdivision. Reportedly, the offsite drainageway was previously large, deep, and filled in with rubble when the Kensington Estates subdivision was constructed.
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The onsite and adjacent surface water features ultimately flow to an unnamed creek, then to Crowders Creek, and then to Lake Wylie in South Carolina. There are no water supply intakes within the 15-mile surface water pathway. The nearest fishery, Crowders Creek, is approximately 2.2 miles downstream of the site. The nearest wetland (as defined in the U.S. Environmental Protection Agency [EPA] Hazard Ranking System) along the 15-mile surface water pathway is approximately 3.5 miles downstream of the site (Versar, 2020).
Groundwater beneath the site is made up of the Piedmont aquifers. Although simply described as a two-component (regolith and bedrock) groundwater system, the aquifers are quite complex systems (USGS, 2008). In general, the groundwater-flow system at the site consists of saturated unconsolidated regolith
(residuum saprolite and alluvium) overlying saturated fractured bedrock. The primary direction of groundwater flow within the residuum on the southern side of the unnamed tributary is to the northwest toward the unnamed tributary. Groundwater flow within the residuum on the northern side of the
unnamed tributary is to the south-southwest toward the unnamed tributary. Groundwater flow in the fractured bedrock aquifer is complex but is apparently to the west toward the Crowders Creek drainage basin. Private and community water supply wells are screened within the fractured bedrock.
Trichloroethene (TCE) contamination is present in the subsurface soils at concentrations greater than the North Carolina Department of Environmental Quality (NCDEQ) Protection of Groundwater Preliminary Soil Remediation Goals (PSRGs) for subsurface soil, possibly representing a continuing source of groundwater contamination. Cobalt, iron, manganese, and thallium were detected in nearly every subsurface soil sample collected and exceeded the NCDEQ Protection of Groundwater PSRGs at several sampling locations, including the background location, possibly indicating that the metal concentrations are naturally occurring. TCE is present in the groundwater both in the residuum and in the fractured bedrock (Versar, 2020).
1.2 Site History
In the 1950s, the southeastern portion of the site was reportedly used for storage and disposal of industrial waste materials. During the early 1950s, 500-pound bales of waste cardboard from local cotton mills reportedly were stored on the property. An estimated 1 million pounds of this material accumulated but
was then destroyed by fire. The parcel was sold in 1955 and was reportedly used by that property owner to recycle chemical drums by emptying their residual contents onto the ground surface, burning, and crushing the drums for scrap metal recycling.
Based on analysis of the historical aerial photographs (Versar, 2020), both GIT parcels and surrounding areas were used for agriculture in 1951 and a residential home was present on the western side of site. The 1956 aerial photograph showed new roads, a fenced-in area, light-toned mounded material, ground scarring, and a shed in the southeastern portion of the site. This is in the same timeframe that the drum recycling activities were reportedly occurring. The northern parcel remained agricultural during this time
period. EPA used the 1956 aerial photograph to focus the remedial investigation (RI).
The previous property owner re-acquired the southeastern land parcel in 1957 and reportedly planted the property with trees. During tree clearing on the southeastern parcel to construct a residence, the property
owner reportedly encountered buried debris of an unspecified nature and stopped the clearing activities. The property was sold to GIT in 1972.
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During the late 1980s, Gaston County Environmental Health Services (GCEHS) collected water samples from the GIT facility’s production well and two domestic wells at 4901 and 4825 Hemphill Road. The results revealed a high concentration of TCE, which significantly exceeded North Carolina Groundwater Standards (NCAC, 2022) and EPA benchmarks. Upon being notified of the contamination, the homeowners installed carbon filtration units on their respective domestic wells, and the GIT facility stopped using its production well for potable water. During the late 1980s and early 1990s, sampling by GCEHS and the North Carolina Division of Environmental Management (NCDEM) detected volatile organic compounds (VOCs) at additional domestic wells near the site. Table 1-1 summarizes the environmental investigations that followed the initial VOC discovery.
Table 1-1. Site History
Name of Event or Report Date(s) Summary
1 NCDEM sampling events at GIT facility 1989 and 1992 Chlorinated chemical cis-1,2-dichloroethene detected at less than 0.5 part per billion in a waste oil underground storage tank northeast of the facility’s main building; NCDEM issued a Notice of Violation to GIT in November 1992.
2 GIT wastewater sampling 1989 A wastewater sample from the facility detected toluene, ethylbenzene, xylenes, phenol, phthalates, and possible fuel-oil residue.
3 GIT soil investigation 1993 A soil investigation at the underground storage tank and in a loading dock area revealed petroleum contamination in the surface soil, affecting approximately 88 cubic yards of soil. Based on the findings of the soil investigation, GIT removed the petroleum-contaminated soil.
4 NCDEM monitoring well sampling events 1993 and 1994 NCDEM installed monitoring wells on and adjacent to the site property; sampling data indicated that TCE groundwater contamination was concentrated beneath the southeastern parcel but extended northwest beneath the adjacent forklift repair facility toward Hemphill Road.
5 EPA and North Carolina Superfund Section cPA/SI 1999 TCE contamination was found in both of the Kensington Estates community wells, greater than 10 µg/L and exceeding federal benchmarks and state groundwater standards. Gaston County and the NCDWQ MRO shut down both Kensington Estates community wells, provided a temporary alternative drinking water supply to the residents, and subsequently connected the subdivision to two existing community wells at the neighboring Amy Acres subdivision.
In July 1999, sampling by NCDWQ detected TCE breakthrough at the domestic well carbon filtration units at 4825 and 4901 Hemphill Road. In response, the property owners replaced the saturated filtration media in each well.
The cPA/SI Report recommended further remedial action under CERCLA.
6 North Carolina Superfund Section SRR March 2001 The SRR reversed the cPA/SI recommendation.
7 North Carolina Superfund Section letter April 2001 The North Carolina Superfund Section sent a letter to NCDWQ MRO and GCEHS recommending the following:
 Connect Amy Acres (and Kensington Estates) subdivision to Gastonia municipal water lines or, alternatively, sample Amy Acres community wells quarterly or semiannually for TCE.
 Connect residences at 4825 and 4901 Hemphill Road to Amy Acres via Kensington Estates.
 Further evaluate domestic well contamination and water usage at 4708 Hemphill Road.
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Table 1-1. Site History
Name of Event or Report Date(s) Summary
8 NCDWQ MRO reporting 2008 TCE concentrations in two community wells supplying the Cedar Grove subdivision, located approximately 1.5 miles southeast of GIT, had been increasing, approaching the 5.0 µg/L federal National Primary Drinking Water Regulations MCL. In 2009, MRO notified the North Carolina Superfund Section that TCE contamination existed in additional community wells near the site. TCE reportedly existed in the two community wells supplying the Wesley Acres subdivision, located directly across Forbes Road, south of Kensington Estates.
9 NCDWQ MRO reporting 2009 NCDWQ MRO notified the North Carolina Superfund Section that TCE contamination existed in the two community wells supplying the Wesley Acres subdivision, located directly across Forbes Road, south of Kensington Estates.
10 North Carolina Superfund Section Removal Request 2009 A Removal Request was transmitted to EPA Region 4 Emergency Response and Removal Branch, incorporating the previously described information. EPA assigned an On-scene Coordinator who sampled the GIT facility production well, two of the onsite monitoring wells, and the domestic wells at 4825, 4901, and 4708 Hemphill Road. Sampling revealed that TCE breakthrough had occurred again in the carbon filters at 4825 and 4901 Hemphill Road; the On-scene Coordinator arranged for replacement of the filtration media in both units. Sample data at GIT and 4708 Hemphill Road were consistent with results from previous investigations.
11 North Carolina Superfund Section SRR 2012 The second SRR recommended the site for further remedial action under CERCLA.
12 North Carolina Superfund Section Expanded Site Inspection
2012 A well survey within approximately 0.5 mile of the GIT property identified 7 community wells and approximately 150 homes served by private drinking water wells. In March 2012, a total of 9 monitoring wells, 1 production well, 7 community wells, 76 private wells, and 5 surface water locations were sampled. TCE contamination exceeding the MCL was found in the private wells at 4727, 4825, and 4901 Hemphill Road, and the Emergency Response and Removal Branch replaced filter systems at 4825 and 4901 Hemphill Road and added a new filter system at 4727 Hemphill Road. TCE contamination was also found in the three surface water samples located in the northwestern corner of the site and downstream.
In August 2012, eight private wells were sampled for VOC analysis. TCE contamination exceeding the MCL was found in the pre-filter samples collected at 4727, 4825, and 4901 Hemphill Road but was nondetect in the post-filter samples. TCE was not detected in the remaining private wells sampled.
In November 2012, eight private wells and the two community wells at the Wesley Acres subdivision were sampled for VOC analysis. TCE contamination exceeding the MCL was found in the pre-filter samples collected at 4825 and 4901 Hemphill Road but was nondetect in the post-filter samples. TCE contamination was detected at the Wesley Acres North Well at a concentration of 2.5 µg/L, which is less than the MCL. TCE was not detected in the Wesley Acres South Well or any of the remaining private wells sampled.
13 North Carolina Superfund Section Expanded Site Inspection
2013 The private potable wells at 4825 and 4901 Hemphill Road were sampled and analyzed for VOCs in three quarterly sampling events. During each sampling event, TCE contamination exceeding the MCL was found in the pre-filter samples collected at 4825 and 4901 Hemphill Road but was nondetect in the post-filter samples.
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Table 1-1. Site History
Name of Event or Report Date(s) Summary
14 RI 2013–2017 The RI consisted of the following:
 Geophysical magnetic anomaly surveys were performed in the southeastern parcel, the western area of the site along Hemphill Road, and the southern area of the site along Hemphill Road; no presence of buried metallic debris was detected.
 Surface and subsurface soil sampling was conducted both onsite and offsite. Low levels of VOCs, semivolatile organic compounds, and pesticides were found in many of the surface and subsurface soil samples. TCE exceeded the NCDEQ PSRG of 21 micrograms per kilograms at three locations; the high TCE concentrations in the subsurface soil in these locations could be a continuing source of groundwater contamination.
 Groundwater samples were collected from temporary wells located on the GIT property and surrounding private properties. In addition, groundwater samples were collected from permanent monitoring wells and private potable wells located on the GIT property and surrounding private properties. The TCE contaminant plume generally follows the surface topography to the west/northwest and extends across Hemphill Road toward the unnamed tributary as predicted by the water table aquifer potentiometric surface gradient. The source of TCE contamination in the residuum appears to be within the southeastern parcel near temporary well DPT-31 and near temporary wells DPT-22 and DPT-24 and permanent well GIT-006 where the drum dumping/recycling activities were reported to have taken place. The lateral and vertical extent of detectable groundwater contamination in the fractured bedrock aquifer was not determined.
 Surface water and sediment sampling was performed within the unnamed tributary and the small pond located to the north of the GIT property. TCE was detected at 11 of the 18 sampling locations at concentrations ranging from 0.81 to 17 µg/L; the highest TCE concentration was found in the seep sample located about 300 feet downstream of the northwestern corner of the GIT property.
 An extensive vapor intrusion study was conducted over a period from July 2013 through April 2017 at onsite and offsite properties. The private residential properties located near the northwestern border of the GIT property and the GIT facility building are located within the residuum TCE plume and are potentially susceptible to vapor intrusion.
15 Interim Action Record of Decision 2018 The major components of the Interim Action Record of Decision consisted of the following:
 Predesign investigation to further define areas requiring remediation and collect additional data needed to design the remedy
 Bench-scale and pilot-scale treatability studies conducted during the remedial design phase to select the appropriate ISCO product and determine appropriate product loading rates
 ISCO treatment of contaminated groundwater using an appropriate oxidant
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Table 1-1. Site History
Name of Event or Report Date(s) Summary
16 Predesign investigation 2019–2020 The predesign investigation consisted of the following:
 Five new monitoring wells were installed onsite, and permanent monitoring wells, temporary monitoring wells, and potable wells (onsite and offsite) were sampled. Analytical results and groundwater elevation data were consistent with previous data.
 Bench-scale and pilot-scale treatability studies were performed to assess the potential for ISCO using permanganate and activated persulfate to oxidize chlorinated solvents, primarily TCE in aquifer samples. The results suggested that the use of permanganate injection using hydraulic fracturing was the preferred method.
 Pilot-scale treatability study results showed that hydraulic fracturing was successful at distributing permanganate and that potassium permanganate is effective at reducing TCE concentrations within the 15-foot radius of influence.
Source: Versar, 2020.
µg/L = microgram(s) per liter
CERCLA = Comprehensive Environmental Response, Compensation, and Liability Act
cPA/SI = Combined Preliminary Assessment/Site Inspection
MCL = maximum concentration level
MRO = Mooresville Regional Office
NCDWQ = North Carolina Division of Water Quality
SRR = Site Reassessment Report

1.3 Description of Remedial Activities
The following will be performed as part of the remedial activities for the site:
 Mobilization and demobilization activities, including underground utility locates, migratory bird survey, and vegetation clearance
 Installation and development of 5 permanent and up to 35 temporary monitoring wells
 Groundwater sampling of 34 permanent monitoring wells (29 existing and 5 new) and up to 35 temporary monitoring wells to further delineate the area requiring treatment and optimize ISCO injections
 Installation of up to 26 temporary ISCO injection wells
 Injection of potassium permanganate using hydraulic fracturing
 Abandonment of the 35 temporary monitoring wells and 26 ISCO injection wells
 Surveying
 Performance monitoring of 14 permanent monitoring wells 1 month, 3 months, and 6 months following the ISCO application to evaluate VOC concentrations within the target treatment zone and
to identify whether additional ISCO injections are warranted
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 Quarterly monitoring of 34 permanent monitoring wells and 4 residential potable wells to evaluate VOC concentrations within the target treatment zone and monitor for contaminant migration; up to 8 quarterly events every 3 months starting at 9 months after ISCO injections.
 Characterization and disposal of the remediation-derived waste.
Mobilization is planned for April 2023. Abandonment of temporary wells will occur after sampling has been completed, which is anticipated to occur in July 2023. ISCO injection wells will be abandoned once remediation objectives are achieved. It will be the Site Safety Liaison’s responsibility to conduct the tasks according to the specified procedures.
The following sections provide general descriptions of these activities. The Technical Management Plan
provides a detailed description of all tasks, including a description of project deliverables (EQ CH JV, 2023a).
1.4 Post-remedial Activity Conditions
Land disturbance from site activities will be minimized and is expected to be limited to a small area
around each new monitoring well and injection location from the drill rig and injection equipment.
Final grading around each of these locations will match the pre-activity conditions as closely as possible.
Reseeding is not expected to be required.
2. Sources of Pollution
Table 2-1 describes the potential pollution sources and activities for this site that may affect the quality of stormwater discharges from the construction site. At least one structural control or BMP is identified in the following subsections to address each of these potential sources to minimize the potential for contact
with stormwater.
Table 2-1. Construction Site Pollutants
Potential Stormwater Contamination Point or Activity Potential Pollutants Potential Problem
Location Control Measure or BMP
Construction site entrance or exit Sediment Tracking soil offsite by heavy equipment has the potential to add sediment to stormwater runoff.
Entrance and exit of construction site Offsite tracking
Fuel and oil storage area Gasoline, diesel, motor oil, hydraulic fluid Leaks or spills from fuel or oil storage containers can contaminate stormwater.
Staging area Material storage and handling, material use
Injection material storage areas Permanganate Leaks or spills from chemical storage containers can contaminate stormwater.
Staging area Material storage and handling, material use
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Table 2-1. Construction Site Pollutants
Potential Stormwater Contamination Point or Activity Potential Pollutants Potential Problem
Location Control Measure or BMP
Heavy equipment use and maintenance
Heavy equipment staging area
Fuel and oil Leaks or spills of fuel or oil from the heavy equipment can contaminate stormwater.
Staging area Vehicle and equipment management, preventive maintenance
Waste storage areas Solid waste, sanitary waste Leaks or spills from solid or sanitary waste containers can contaminate
stormwater.
Staging area Waste management
Loading or unloading and material use ISCO chemicals, waste Leaks or spills of materials can contaminate stormwater as they are loaded, unloaded, or used around the site
Staging area Material storage and handling, material use
Decontamination Sediment, site contaminants[a], ISCO
chemicals
Sediment, site contaminants, and ISCO chemicals are mobilized as equipment is decontaminated.
Staging area Decontamination
[a] TCE is the primary site contaminant.
3. Stormwater Management and Sediment Controls
3.1 Spill Prevention, Control, and Response
Spills will be minimized and controlled using the procedures in the Hemphill Road TCE Superfund Site Spill Control Plan (EQ CH JV, 2023b) The Spill Control Plan also contains spill response procedures.
3.2 Material Storage and Handling
The following proper material storage and handling practices are to be implemented in all areas where delivery and storage or materials may be detrimental to the environment to prevent spills or leaks into the stormwater:
 Equipment and vehicles will be fueled offsite whenever possible. Fuel, if stored onsite, will be stored in a bermed area in containers compatible with the fuel stored. Section 3.4 provides further information on vehicle and equipment management.
 Equipment and vehicles maintenance will occur offsite whenever possible. Vehicle maintenance liquids (for example, antifreeze, motor oil, hydraulic fluid) will be stored either indoors or in bermed areas in containers compatible with the material stored. Section 3.4 provides further information on
vehicle and equipment management.
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 ISCO chemicals will be stored in a secure location and within secondary containment, properly
labeled as “Oxidizer.”
 Safety data sheets will be made available for all materials.
 Sufficient separation will be allowed between storage containers to allow for cleanup and emergency
response.
 Chemically incompatible materials will not be stored together or in the same storage facility.
 All containers and materials will be properly and legibly labeled.
 Hazardous material storage and handling will comply with applicable regulations and requirements.
 Leaks or spills will be contained and cleaned up immediately.
3.3 Material Use
The following practices are implemented to ensure minimal water quality impacts from the use of construction materials:
 Safety data sheets will be made available for all materials.
 Original labels will not be removed. Materials will be re-labeled properly to maintain current, legible labels with proper safety and disposal information.
 Less hazardous, recycled, or non-toxic materials will be used whenever possible.
 Used and excess materials will be recycled or properly disposed.
 Materials will be used only where and when necessary to complete the remedial activity. Excess
application of materials will be avoided.
 Wastes will be segregated and handled by appropriately licensed contractors and disposed of according to applicable regulations. Section 3.6 provides further information on waste management.
The subcontractor is responsible for identifying proper material use measures for all materials used at constructions site projects.
3.4 Vehicle and Equipment Management
The following practices for this BMP are to be used at facilities or designated work areas during vehicle and equipment staging, fueling, cleaning, and maintenance to prevent associated pollutants from entering stormwater:
 Cleaning, washing, and maintenance will be performed in a centralized station offsite where possible.
 Designated onsite stations should be located indoors on impervious surfaces where possible.
 Drip pans or absorbent materials will be used under equipment to catch/contain leaks.
 Plastic will be placed under the drill rigs when actively drilling to catch or contain leaks.
 The amount of toxic or hazardous solvent used will be eliminated or reduced where possible.
 Proper waste or recycling drums will store used or spilled fluids; materials will be separated and
recycled when possible.
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 Liquid waste will not be poured into floor drains or sinks.
 Hosing down of workstations will be avoided.
 Vehicles and equipment will be checked routinely for leaking oil or fluids.
 Proper spill and illicit discharge reporting and cleanup procedures will be followed for both
hazardous and nonhazardous materials.
3.5 Decontamination
A temporary decontamination area will be established within the site. Washing will be conducted within a contained area, and the wash water and solids generated will be contained, collected, sampled, and disposed of according to federal, state, and local regulations.
Under no circumstances will wash water be discharged onto the ground or into a drainageway.
3.6 Waste Management
This subsection identifies and describes measures to be used to prevent the discharge of building or other similar materials to surface waters of the State.
Waste generated is expected to include solid waste (such as, general trash, used personal protective equipment) sanitary waste, and nonhazardous waste.
Waste will be managed according to the Site Management and Waste Management Plan (EQ CH JV,
2023c).
The following are general requirements for the site specifically to prevent stormwater pollution:
 Litter will be minimized in all construction areas and collected on a regular basis into water-tight dumpsters. Trash receptacles will be provided in various locations within the construction site boundaries. Collected trash will not be placed near drainage inlets or watercourses. A trash hauling contractor will be used to properly dispose of the collected waste in a timely manner.
 Dumpsters will not be washed out at the construction site.
 Storage areas for solid waste will be located at least 50 feet from drainageways and watercourses, and will not be located in areas susceptible to frequent flooding. Sediment barriers (such as berms, dikes, or other temporary diversion structures) will be used as necessary to prevent stormwater runoff from contacting stored solid waste at the site.
 Solid waste will be segregated properly into various categories for recycling or disposal. Proper disposal is required for each waste category.
 The contractor will make every attempt to recycle useful vegetation, packaging material, and surplus
construction materials when practical. Most construction materials can be recycled at recycling facilities.
 Sanitary wastes will be stored in individual portable san-o-lets, which will be periodically hauled off
by a licensed disposer.
 Temporary sanitary facilities will be located at least 50 feet from drainageways, inlets, receiving waters, areas of high traffic, and areas susceptible to flooding or damage by construction equipment.
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 In project areas susceptible to strong winds, temporary sanitary facilities will be secured to prevent
overturning.
3.7 Good Housekeeping
Good housekeeping procedures will be followed during this project, including keeping the site free of
trash and debris, keeping material and equipment storage areas clean, and ensuring timely, proper disposal of project waste.
3.8 Preventive Maintenance
Equipment used during this project will be maintained in good working condition and will be subject to routine, preventive maintenance in according with the manufacturer’s recommendations.
3.9 Offsite Tracking
Once mobilization is complete, heavy equipment will not leave the site until work is complete for that piece of equipment. Before leaving the site, the equipment will be dry-brushed or decontaminated as appropriate. Section 3.5 provides further information on decontamination measures.
If offsite tracking of sediment is noted, it will be swept using a broom or push sweeper and removed.
4. Erosion Prevention Best Management Practices
Based on the limited disturbance, structural controls (such as, fiber rolls, silt fence) are not expected to be necessary.
4.1 Protect Vegetation and Minimize Exposed Surfaces
Vegetation is the most effective way to control erosion, and disturbing soil removes this natural protective measure. Trees, bushes, and strips of natural vegetation are natural elements that serve to help hold soil particles in place, absorb the impact of rainfall, encourage infiltration, and slow the velocity of runoff. Avoiding disturbance is the optimal measure to control erosion and sedimentation.
The existing vegetation will be preserved as much as possible using one or more of the following measures:
 Provide designated entries and exits as part of work access plan to minimize the extent of land disturbance
 Define limits of construction on the plans and in the field during mobilization to the maximum extent possible
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5. References
EQ CH JV. 2023a. Technical Management Plan, Hemphill Road TCE Superfund Site, Gastonia, Gaston County, North Carolina. January.
EQ CH JV. 2023b. Spill Control Plan, Hemphill Road TCE Superfund Site, Gastonia, Gaston County,
North Carolina. March.
EQ CH JV. 2023c. Site Management and Waste Management Plan, Hemphill Road TCE Superfund Site,
Gastonia, Gaston County, North Carolina. March.
North Carolina Administrative Code (NCAC). 2022. Title 15A of the NCAC, Subchapter 02L Groundwater Classification and Standards. Readopted Effective June. http://reports.oah.state.nc.us/ncac/title%2015a%20-%20environmental%20quality/chapter%2002%20-%20environmental%20management/subchapter%20l/subchapter%20l%20rules.pdf.
U.S. Geological Survey (USGS). 2008. Hydrologic Setting, Ground-Water Flow, and Ground-Water
Quality at the Langtree Peninsula Research Station, Iredell County, North Carolina, 2000-2005, Scientific Investigations Report. 2008-5055.
Versar, Inc. (Versar). 2020. Final (100%) Remedial Design, Hemphill Road TCE Site, Gastonia, Gaston
County, North Carolina. July.

Figures
Figure1-2_Site_Layout
Hemphill Site
Gastonia City Limits
Streams
LEGEND
Figure_1-1_Site_Location_v2
Source: Versar, 2020. Final (100%) Remedial Design, Hemphill Road TCE Site, Gastonia, Gaston County, North Carolina.
Figure 1-1. Site Location
Hemphill Road TCE Superfund Site
Gastonia, Gaston County
North Carolina
LEGEND
Hemphill Site
Streams
Figure_1-2_Site_Layout_v2
Source: Versar, 2020. Final (100%) Remedial Design, Hemphill Road TCE Site, Gastonia, Gaston County, North Carolina.
Figure 1-2. Site Layout
Hemphill Road TCE Superfund Site
Gastonia, Gaston County
North Carolina
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City Limits
Countour at 100 feet
Countour at 500 feet
Countour at 20 feet
Countour at 4 feet
Countour at 2 feet
LEGEND
Figure_1-3_Site_Topography_v2
Source: Versar, 2020. Final (100%) Remedial Design, Hemphill Road TCE Site, Gastonia, Gaston County, North Carolina.
Figure 1-3. Site Topography
Hemphill Road TCE Superfund Site
Gastonia, Gaston County
North Carolina
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U n n a m e d T r i b u t a r y
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