4101_Guilford_CityHighPoint_Riverdale_MSWLF_Seaboard_FiveYearReport_FID1773672_20230227

FIRST FIVE-YEAR REVIEW REPORT
FORMER SEABOARD CHEMICAL CORPORATION FACILITY AND
RIVERDALE DRIVE LANDFILL SITE
JAMESTOWN, NORTH CAROLINA
EPA ID No. NCD071574164
Prepared by
SEABOARD REMEDIAL ACTION TRUST
c/o de maximis, inc.
1550 POND ROAD, SUITE 120
ALLENTOWN, PA 18103
2/27/2023
R. Craig Coslett, Project Coordinator Date

Table of Contents
LIST OF ABBREVIATIONS & ACRONYMS......................................................................................... 2
I. INTRODUCTION...................................................................................................................................
3
SiteBackground......................................................................................................................................
3
FIVE-YEAR REVIEW SUMMARY FORM.........................................................................................
4
II. RESPONSE ACTION SUMMARY......................................................................................................
5
ResponseActions....................................................................................................................................
5
SiteRelated.............................................................................................................................................
6
ICSummary Table..................................................................................................................................
6
Collection/Treatment System..................................................................................................................
6
CollectionSystem(s)...........................................................................................................................
7
TreatmentSystem(s)...........................................................................................................................
7
IrrigationControls...................................................................................................................................
9
Statusof Implementation........................................................................................................................
9
Systems Operations/Operation & Maintenance(O&M).......................................................................
10
Inspections............................................................................................................................................
11
III. PROGRESS SINCE THE LAST REVIEW.......................................................................................
11
IV. FIVE-YEAR REVIEW PROCESS....................................................................................................
12
DataReview..........................................................................................................................................
12
GroundwaterData.................................................................................................................................
12
SurfaceWater Data...............................................................................................................................
13
OperationalData...................................................................................................................................
15
SiteInspection.......................................................................................................................................
25
V. TECHNICAL ASSESSMENT............................................................................................................
25
QUESTIONA.......................................................................................................................................
25
QUESTIONB.......................................................................................................................................
26
QUESTIONC.......................................................................................................................................
27
VI. ISSUES/RECOMMENDATIONS.....................................................................................................
27
VII. PROTECTIVENESS STATEMENT................................................................................................
29
VIII. NEXT REVIEW..............................................................................................................................
29
APPENDIX A — Reference List...........................................................................................................
30
APPENDIX B — Sample Copy of Weekly Log Checklist....................................................................
31
FIGURE1 — Site Location Map...........................................................................................................
32
FIGURE2 — Site Features Map............................................................................................................
33
FIGURE 3 — Process Flow Diagram.....................................................................................................
34
FIGURE4 — VOC Trend Graphs..........................................................................................................
35
FIGURE 5 — 1,4-Dioxane Trend Graphs..............................................................................................
36
1

LIST OF ABBREVIATIONS & ACRONYMS
2017 CCR 2017 Construction Completion Report
AOC
Administrative Order of Consent
ARAR
Applicable or Relevant and Appropriate Requirement
CERCLA
Comprehensive Environmental Response, Compensation, and Liability Act
CFR
Code of Federal Regulations
COC
Constituent of Concern
DB Pg
Deed Book and Page
DEQ
North Carolina Department of Environmental Quality
EPA
United States Environmental Protection Agency
GC ROD
Guilford County Register of Deeds
GPM
Gallons Per Minute
FYR
Five -Year Review
HMI
Human Machine Interface
ICs
Institutional Controls
LCHT
Leachate
LS
Lift Station
LUR
Land Use Restriction
NCP
National Oil and Hazardous Substances Pollution Contingency Plan
NIS
Northern Intermittent Stream
NPL
National Priorities List
O&M
Operation and Maintenance
PB Pg
Plat Book and Page
PC
Project Coordinator
PE
Profession Engineer
PG
Professional Geologist
PLC
Programmable Logic Controller
PRP
Potentially Responsible Party
RAO
Remedial Action Objectives
RCRA
Resource
ROD
Record of Decision
RPM
Remedial Project Manager
RW
Recovery Well
SITE
Seaboard Chemical / Former Riverdale Drive Landfill
SIS
Southern Intermittent Stream
SRM
Soil Residue Mound
TBC
To be considered
TM#
Technical Memorandum (numbered 1 through 11)
VOC
Volatile Organic Compound

I. INTRODUCTION
As provided in Paragraph F of the Statement of Work, Exhibit A to the Declaration and Order (Docket #
08-SF-249), attached to the Remedial Action Settlement Agreement (RASA) dated December 29, 2008,
for the Former Seaboard Chemical and Riverdale Drive Landfill Site, the purpose of a Five -Year Review
(FYR) is to evaluate the effectiveness of the Approved Remedy and to assess whether the Approved
Remedy remains effective and is protective of human health and the environment. This FYR has been
prepared in substantial compliance with the United States Environmental Protection Agency's (EPA's)
Comprehensive Five -Year Review Guidance and provided to the Division within 180 days of the end of
each five-year reporting period, with the first reporting period commencing on the date the system was
placed into operation.
de maximis, inc., Babb and Associates, and Glover Engineering, PLLC have prepared this five-year
review on behalf of the Settling Remediators to the RASA (the City of High Point, Seaboard Group Il and
the Work Parties), pursuant to the paragraph F of the Statement of Work and in accordance with the
Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) Section 121,
consistent with the National Contingency Plan (NCP)(40 CFR Section 300.430(f)(4)(ii)), and considering
EPA policy.
This is the first FYR for the Former Seaboard Chemical Corporation Facility and Riverdale Drive Landfill
Site. The triggering action for this review is the August 25, 2017 notice of System Operation. The FYR
has been prepared due to the fact that hazardous substances, pollutants, or contaminants remain at the site
above levels that allow for unlimited use and unrestricted exposure (UU/UE).
The Former Seaboard Chemical Facility and Riverdale Drive Landfill Site Five -Year Review was led by
R. Craig Coslett, Project Coordinator, Gary Babb, PG, and Rich Glover, PE. The relevant entities
including the PRPs and NCDEQ representatives were notified of the initiation of the five-year review.
The review covers the period of August 2017 through August 2022.
Site Background
The general vicinity and Site location are shown on Figure 1. The Site consists of two properties as shown
in Figure 2, the former Seaboard Chemical facility property located at 5899 Riverdale Drive, Jamestown,
NC and the adjacent Riverdale Drive Landfill, a closed municipal solid waste landfill. The former
Seaboard Chemical property is approximately 10 acres, while the Riverdale Drive Landfill consists of
approximately 102 acres and bounds the former Seaboard facility on three sides.
Between 1974 and 1989, Seaboard Chemical Corporation operated solvent recovery and fuel blending
processes at the facility. The facility was granted Interim Status under the Resource Conservation and
Recovery Act ("RCRA") as a treatment, storage, and disposal facility in 1982. The facility was divided
into 13 operating areas that included, among other things, distillation, fractionation, and condensation of
organic solvent wastes. In addition, three unlined surface impoundments were in service at the facility
during the time that Seaboard Chemical was in operation. The corporation declared bankruptcy and was
not able to fund the cost of performing the necessary site closure and remediation. Removal activities were
conducted during 1990 and 1992 to remove all remaining waste materials and certain tanks and equipment
from the Seaboard Chemical property. A Removal Action was conducted by the Seaboard Group I,
formed by parties that may have used the services of Seaboard Chemical Corporation in the past. The
Seaboard Chemical property was administered as an asset of the bankruptcy estate of Seaboard Chemical
Corporation by J. Brooks Reitzel, Jr., bankruptcy trustee. The Trustee was not able to dispose of the
3

property in the course of the bankruptcy proceedings, and ownership is believed to have reverted to the
dissolved Seaboard Chemical Corporation by operation of law. Seaboard Group II and the City of High
Point have a recorded perpetual easement to perform remedial activities on the property.
The closed Riverdale Drive Landfill (Landfill) was operated, using customary methods in general use at
the time, from the 1950's until October 1993. The Landfill was permitted by the NCDEQ Solid Waste
Section in 1979. During Landfill operations sections of the two tributary streams that dissect the landfill
property were piped so that the landfill could be expanded, and solid waste was used to fill the drainage
valleys. From approximately 1966 until 1970, Landfill operations also included the disposal and open
burning of spent solvents. The burn pits were periodically cleaned of residue which was accumulated in a
mound located near the former burn pits. Presently this residue mound consists of approximately 600
cubic yards of contaminated soil and is referred to as the "soil residue mound". The soil residue mound
has been capped with an impermeable synthetic liner and stabilized with a vegetative cover. In 1989, a
leachate collection system was added to control leachate seeps along the slopes of the Landfill. Leachate
collection lines were also installed beneath the landfill parallel to the Southern Intermittent Stream piped
section to intercept leachate flow in the filled stream valley. The leachate from this collection system is
accumulated in concrete storage tanks. The closed Landfill is now capped with a minimum of two feet of
native soil and a vegetative cover.
After the Removal Action, the Seaboard Group II (Group) was formed to perform a remedial investigation
and to prepare a baseline risk assessment/feasibility study for the former Seaboard site. As recommended
by the NC Division of Waste Management, the Group and the City entered into an agreement to jointly
perform a remedial investigation, because the close proximity of the Landfill and former Seaboard facility
made joint investigation of the two properties (Site) advantageous for both the City and the Group. The
Parties then entered into an Administrative Order on Consent (AOC) dated January 30, 1996 with the
State to perform the remedial investigation. The feasibility study was conducted under a separate AOC
dated July 22, 1997.
FIVE-YEAR REVIEW SUMMARY FORM
4

Author name (Project Coordinator): R. Craig Coslett I
Author affiliation: de maximis, inc. I
Review period: 8/1/2017 — 8/1/2022 I
Date of site inspection: 2/15/2023 I
Type of review: Policy I
Review number: 1 I
Triggering action date: 8/25/2017 I
Due date eve years after triggering action date): 2/25/2023 I
II. RESPONSE ACTION SUMMARY
Response Actions
Remedial investigations conducted at the Site have documented the presence of chlorinated and non -
chlorinated hydrocarbon compounds in soils, landfill leachate, groundwater (shallow and deep), and
surface water. The remedial investigation results also indicated the presence of dense non -aqueous -phase
liquids in the fractured bedrock aquifer underlying the Site.
The Remedy Recommendation Document, approved by the Division of Waste Management on September
27, 2005, presents a protective remedial strategy for the impacted media based on the results of the
remedial investigation, baseline risk assessment, and feasibility study. The remedial action consists of
groundwater extraction and treatment in combination with institutional controls including site access
control, recorded land use restrictions, and restriction of water supply well construction. The remedy was
designed and constructed to prevent movement of COCs into Randleman Reservoir and the Southern
Intermittent Stream, as well as to prevent exposure to impacted soils and groundwater at the Site.
The objectives of remedial action at the Site as listed in the Remedy Recommendation Document include
the following:
• Contain the contaminated soils at the source areas to prevent direct contact by potential human and
environmental receptors, reduce percolation and intrusion of storm water and reduce migration of
compounds of concern ("COCs") into the groundwater,
• Control migration of landfill leachate to prevent discharge to surface water at the Site,
• Control migration of contaminated groundwater at the site to prevent offsite migration and
unacceptable impacts to surface water,
• Achieve compliance with North Carolina surface water quality standards for the COCs in the
surface water of the onsite streams,
• Achieve compliance with North Carolina groundwater quality standards for the COCs in the
groundwater beneath the Site, and
• Restrict future Site uses that could present potentially unacceptable exposure risks (e.g., residential
development, use of impacted groundwater, etc.).
For ease in description and comparison to the remedial objectives the components of the Remedial Action
have been broken out into the following categories: Site Related and Collection/Treatment Systems.
5

Site Related
As previously mentioned, the Site consists of two properties, the 10-acre former Seaboard Chemical
facility property located at 5899 Riverdale Drive, Jamestown, NC and the adjacent 102-acre Riverdale
Drive Landfill. Both properties have been closed consistent with local, state and federal requirements and
have met the goals of the remedial action objectives by restricting future Site uses that could present
potentially unacceptable exposure risks, including:
• Have been secured in a manner that restricts unauthorized access (fencing).
• Are subject to recorded land use restrictions (LURs) on future development and groundwater
usage.
• Each property has been closed pursuant to approved closure plans. (Seaboard February 1993
letter approval, April 1994 Riverdale Drive Landfill Post Closure Plan)
• Are inspected on an approved schedule to ensure protectiveness.
In addition, in a letter dated January 8, 2021the NCDEQ issued its satisfactory 5-year review of the
hazardous waste management permit for the Seaboard Chemical facility.
IC Summary Table
Media, engineered
ICs Called
Title of IC
controls, and areas that do
ICs
for in the
Impacted
IC
Instrument
not support UU/UE based
Needed
Decision
Parcel(s)
Objective
Implemented and
on current conditions
Documents
Date (orplanned)
Guilford
Restrict all uses of
Declaration of
Seaboard Chemical
County
property other agency
Perpetual Land
Property — 10.323ac
Yes
Yes
Parcel
approved activities.
Use Restrictions,
Number
Remedial Activities
GC ROD P.B.
158477
have been approved
179 Pg. 17, 2010
Guilford
Restrict all uses of
Land Use
Materials Recycling
County
property other agency
Restrictions, GC
Facility (MRF) —
Yes
Yes
Parcel
approved activities.
ROD P.B. 186
11.657ac
Number
Remedial Activities
Pg. 80, D.B 7588
209709
have been approved
P . 2202, 2014
Guilford
Restrict all uses of
Land Use
Riverdale Drive Landfill
County
property other agency
Restrictions, GC
— 101.779ac
Yes
Yes
Parcel
approved activities.
ROD P.B. 185
Number
Remedial Activities
Pg. 21, DB 7588
209705
have been approved
P . 2191, 2013
Collection/Treatment System
Construction of the collection/treatment system is documented in the April 2017 Construction Completion
Report (2017 CCR) which was approved by NCDEQ on July 25, 2017. This 2017 CCR documents the
final status of the remediation systems as constructed and includes modifications made to the components
of the system after submittal of the January 15, 2014 Remedial Monitoring and Effectiveness Evaluation
Plan. Additional modifications implemented during the current reporting period are provided in the Status
of Implementation below. The constructed elements of the Collection/Treatment systems documented in
the 2017 CCR include:
Con

Collection System(s)
A network of 8 (eight) groundwater recovery wells are utilized for extraction of affected
groundwater. These wells include 1 (one) deep well, PWDR1, and 7 (seven) shallow wells, RW-
SIS 1, RW-SIS2, RW-SIS3, RW-SIS4, RW-LFS 1, RW-LFS2, and RW-NIS. In addition, 5 (five)
leachate collection tanks, and the NIS sump (2 pumps) accumulate landfill leachate at the perimeter
of the landfill in select locations and from the Northern and Southern Intermittent Stream discharge
areas. The locations of the recovery wells and leachate collection tanks are shown in Figure 2.
Flows from recovery wells RW-SIS 1, RW-LFS 1, RW-LFS2, and RW-NIS are combined with the
flows from the leachate tanks in Lift Station 1 (LS-1). The discharge from LS-1 is pumped to Lift
Station 2 (LS-2) where the flow is combined with the flows from PWDR-1, RW-SIS2, RW-SIS3,
and RW-SIS4.
Treatment System(s)
The components of the treatment systems are physically located on both properties with the
majority of the components being located on the former landfill property. The SCADA control
system, LS-2, filter building, and the clarifier are located on the former Seaboard property. The
description of the Treatment System is broken down between the Mechanical Treatment System
(Mechanical System) and the Natural Treatment System (Natural System). All collected water
(groundwater and leachate) is processed through the mechanical system to remove the majority of
constituents of concern (COCs) prior to processing through the natural system to address the
remaining constituents.
Mechanical Treatment System
The Mechanical System refers to the equipment and processes in the extraction well network,
leachate collection network, LS-1, clarifier system, sludge handling system, filter building, LS-
2, and the irrigation network up to the node control panels (See Figure 3 — Process Flow
Diagram). The node control panels separate these components and their associated treatment
equipment from those used in the Natural System. The division between the Mechanical
System and the Natural System is at the node control panel buildings on the Landfill's East
and West Lobes. Within each node control building there is a large electrical control panel that
contains the data loggers and multiplexers, as well as the translation interfaces for the SCADA
control system. The Mechanical System is comprised of the following major components:
• Lift Station 1 — This is a single enclosure used to collect and transfer the recovered
groundwater and the leachate from most of the sources and pump it to the inlet manifold
in Lift Station 2 (LS-2). This includes flow from the five leachate collection tank pumps,
the NIS leachate sump (two pumps), and recovery wells RWNIS-1, RWSIS-1, RWLFS-
1, and RWLFS-2. LS-1 is located nearly 80 feet (vertically) below the elevation of LS-2
near the Landfill perimeter road. LS-1 contains the pneumatic controls for most of the
shallow groundwater recovery wells and all the leachate pumps, and the inlet header from
the leachate and shallow groundwater recovery well networks.
• Lift Station 2 — LS-2 consists of seven enclosures used to regulate the inlet flow to the
clarifier, provide pneumatic control for the remaining shallow groundwater recovery
wells, and store and transfer the process flow from the Mechanical System to the
irrigation network in the Natural System. The LS-2 inlet manifold contains the
proportioning and shutoff valves used to regulate the system flow into the clarifier, then
into the filter building, and from the filter building into the settling vat. It also receives
the treated process flow from the settling vat proportioning manifold and controls the
7

flow to the discharge networks.
• Clarifier System — The clarifier is a vertical wall cylindrical clarifier system which is
approximately 15 feet tall and 18 feet in internal diameter. It receives all the flow from
all sources in LS-1 and LS-2 and performs the initial treatment to remove mineral salts
by pH adjustment, flocculation and settling.
• Sludge Handling System — The sludge from the bottom of the clarifier is pumped to one
of two sludge dewatering boxes (referred to as tipper boxes). These two dewatering boxes
are mounted on elevated stands to allow them to be tipped to empty the dewatered sludge.
A polymer is added to the sludge in the line between the clarifier and the tipper boxes to
enhance dewatering. Sludge is directed to one of the tipper boxes until it is full. At that
time, flow is directed to the idle tipper box, and the full box drains any free water to a
sump that is pumped into the clarifier equalization tank. Once the sludge is dried
sufficiently, the box is emptied, and the solids disposed on -site.
• Filter Building — The filter building receives flow from the clarifier including LS-1 and
the shallow bedrock recovery wells RWSIS-2, RWSIS-3, RWSIS-4, and deep
groundwater pumping well PWDR-1. It provides filtering to 25-microns+/-, addition of
a sequestrant, and polishing in a 6-tray air stripper. It is then passed through to the settling
vat in the effluent treatment system.
• Maintenance Building — The maintenance building is located near the filter building and
contains the lime and ferric chloride storage tanks, chemical feed pumps, air compressors
and other appurtenances associated with the clarifier chemical feed systems. It is also
used for storage of spare parts and equipment.
Natural Treatment System
The Natural System is a 32±-acre tree stand consisting of a variety of conifer tree species first
planted in 2007 located entirely on the former landfill property. An irrigation system for the
tree stand is divided into 16 approximately two -acre zones that can be activated sequentially
to dispense water at approximately 50 gpm per zone. The Natural System is comprised of the
following components, including irrigation control:
• The tree stand, first planted in 2007, occupies 22 acres on the west lobe of the landfill and
about 10 acres on the east lobe;
o The tree species include loblolly pine, Virginia, and Japanese Black pine as well as
eastern red cedar.
o The trees are arranged in rows 10 feet apart, and trees within a row are roughly on 10-
foot centers (approximately 435 trees per acre).
• The irrigation system for the tree stand is divided into 16 approximately two -acre zones
that can be activated sequentially to dispense water at about 50 gpm (0.055 inches per
hour).
• Each irrigation zone has multiple drip lines.
• Liquid fertilizer can be dispensed to the tree stand via the drip lines (fertigation). A
fertilizer tank that can be filled with liquid nutrients is connected to a pump, solenoid valve
and a flow meter. Nutrient solution can be injected, at a specific dilution factor, into the
irrigation water.
N.

Irrigation Controls
In each of the zones, the drip -irrigation system is monitored to prevent over -irrigation and excessive
drainage below the root zones of the trees. Each irrigation zone is instrumented with sensors that provide
data to the PLC that provides the operator with information needed to manage the volume of irrigation
being used in each of the zones.
• Irrometer Watermark sensors measure resistance to the flow of electricity expressed in kohms
(kD)•
• Soil temperature sensors. On each lobe of the landfill, in one of the nests of soil moisture sensors,
three soil temperature sensors were installed at the same depth as the moisture sensors. A fourth
sensor in each nest was installed at approximately 4-inches below grade to monitor freezing at the
drip line elevation.
Operating decisions for the irrigation system are documented on the weekly logs and verified in the field.
Status of Implementation
Following construction completion of the collection and treatment system, the Mechanical System and
Natural System were subject to testing procedures to prove the system was operating as designed. This
"prove -out" testing is presented in detail in the Construction Completion Report and documented that
different components of the constructed elements could meet the design requirements that were
established to address the Remedial Action Objectives for the system. Throughout the operation period,
the system continued to be optimized to address inefficiencies identified. The following provides a
summary of items completed during this reporting period.
• Installation of surge suppressors — lightning strikes and electric surges affected equipment causing
extended down time on more than one occasion following startup. Surge suppression has been
installed throughout the electrical components.
• Sparge Tank Addition — To optimize treatment, a 200-gallon sparge tank was installed as the initial
phase of treatment. The sparge tank provides a number of benefits as the initial treatment step
including; balances flow (minimizes peaks of COCs entering the clarifier), increases pH, and mixes
the influent coming from the different extractions points prior to chemical additions and further mixing
in the clarifier unit.
• Abandonment of Monitoring Wells — In a letter dated May 2018 a list of 26 existing monitoring wells
were proposed for abandonment as they were determined to be not needed for future monitoring at the
Site. In a letter dated June 5, 2018, DEQ provided approval of the recommended abandonment work
which was completed in the summer of 2018.
• PLC/HMI Update — In a letter dated April 18, 2019, a proposal to replace the PLC/HMI control system
to eliminate electronic issues that stemmed from obsolete equipment was submitted to DEQ. The
proposed work included installation of new hardware (valves and controllers) to replace equipment
that was no longer available, wiring of new equipment and installation of new programmable control
logic. The proposal also included complete removal of the equipment associated with the AOP+
system that was non-functional. This work was approved by DEQ in a letter dated May 6, 2019.
• Remedial Monitoring and Effectiveness Evaluation Report — In April 2020, the Seaboard Group II and
City of High Point (Parties) submitted the Remedial Monitoring and Effectiveness Evaluation Report
that documented operations, maintenance and monitoring of the Extraction and Treatment systems for
the Former Seaboard Chemical and Riverdale Drive Landfill Sites for the initial 2 years following
DEQ approval of the Remedial Action construction. A recommendation that came out of the April
I

2020 Report was to evaluate the shallow groundwater interactions within the Southern Intermittent
Stream (SIS) area.
Additional Monitoring Well Installation — During the Spring and Summer of 2021, an evaluation of
the existing extraction system, COC source areas, and capacity of the current treatment system
(mechanical and natural) was conducted to determine if modifications would increase the effectiveness
of the remedial system and improve the removal of COC mass. These efforts included the installation
and sampling of additional assessment monitoring wells in the SIS basin area, drawdown tests of the
existing extraction wells at the SIS basin, and yield testing of select existing wells at the Seaboard
Property near the former Pond 3 area. This work led to the submittal of Technical Memorandum 11.
Technical Memorandum 11 (TM-11) — On February 3, 2022, TM -II was submitted to DEQ to
evaluate the effectiveness of adding select wells in the vicinity of the SIS basin and near the former
Pond 3 Area of the Seaboard property to the extraction system. TM -I I was conditionally approved
by DEQ in a letter dated February 18, 2022. The conditions of the approval (IE additional monitoring)
were addressed. Work associated with TM -I I is being conducted currently with the initial quarterly
report being submitted to DEQ on January 17, 2023.
Systems Operations/Operation & Maintenance (O&M)
Operation, Maintenance, and Monitoring of the system has been conducted by Piedmont Industrial
Services since start-up.
As previously presented, following construction completion of the collection and treatment system, the
mechanical and natural systems were subjected to testing procedures to prove the system was operating
as designed. "Prove -out" testing documented that different components of the constructed elements could
meet the design requirements that were established to address the Remedial Action Objectives for the
system. The Operation and Maintenance (O&M) plan was developed to outline data collection and
monitoring requirements in addition to operation requirements to run the collection and treatment systems.
The physical data collection and monitoring activities are documented on a weekly basis by the O&M
contractor following the weekly log checklist. A sample copy of the weekly log checklist is provided as
Appendix B. The collected information is then used to prepare summaries of Site activities that are
submitted to NCDEQ as Quarterly Progress Reports. Data collected weekly and used to prepare the
Quarterly Progress Reports includes:
• Meter Readings — Weekly flow information from various locations including leachate collection
system, groundwater extraction wells, discharge to natural treatment areas, compressor run times, and
pump counter information from individual extraction locations (wells and sumps).
• Chemical Levels — Tank levels are tracked showing chemical usage of the various chemicals employed
in operating the system (lime slurry, flocculant, sulfuric acid, sequestrant, and sodium hydroxide).
• In -House Lab Samples — Weekly tests are run on the effluent in order to check for changes prior to
the monthly sampling. The weekly tests are run on -site for iron, total suspended solids, pH, oxidation-
reduction potential, conductivity, and total dissolved solids. Changes in effluent parameters alert the
operator of issues so that the necessary actions can be taken to resolve any potential problems.
• Contract Lab Samples — Monthly samples are collected from the raw influent water, prior to the Air
Stripper, and effluent water prior to discharge to the Natural System. These samples are analyzed by
a NC Certified Laboratory for volatile organic compounds, inorganics, hardness, pH, total dissolved
and suspended solids, and 1,4-dioxane. These samples evaluate the effectiveness of the metals
removal process and air stripper operation prior to distribution to the Natural System.
10

• Well Transducer Readings — Weekly well levels are recorded in the observation wells that are
equipped with level transducers. These levels confirm the drawdown by the recovery wells and offer
evidence of the capture zone.
• Comments — Specific details on run time, alarms, tasks completed, inspections, shutdowns, and
resolutions. Further detail is provided by the operator in the transmittal of the weekly logs.
• Checklist — The check list is composed of dozens of items that need to be checked or serviced for
preventative maintenance. The checklist items are broken into categories of bi-weekly, weekly,
monthly, and quarterly.
Inspections
Inspections of the Site and operations are conducted on a weekly basis as noted on the Weekly Log
Checklist. Inspections are conducted during routine operations and are documented in the daily logbook
when issues are identified. Sitewide inspections are also conducted on a quarterly basis and issues are
identified in the Site logbook and reported in quarterly reports. If issues are identified, a narrative
summary of the issues and the corrective measures taken are provided.
The Landfill is also monitored separately by the City on a quarterly basis for the presence of
methane/explosive gases at the waste boundary. These monitoring events are conducted by a third -party
contractor and the results are submitted to NCDEQ quarterly. In addition to the routine site inspections
of the natural treatment areas, weekly inspections are conducted by City personnel to identify any post -
closure issues involving erosion control, site security, leachate seepage, etc. Inspections are also
conducted after significant rainfall events to assure site erosion control measures remain effective.
III. PROGRESS SINCE THE LAST REVIEW
This is the 1st FYR for the Seaboard Chemical/Former Riverdale Drive Landfill Site.
The Remedy for the Site has been constructed as designed with approved revisions documented in
Technical Memoranda # 1 through # 10. Additional extraction as documented in Technical Memorandum
#11 is currently being evaluated. The constructed remedy has been effective at addressing the Remedial
Action Objectives as listed in the Remedy Recommendation Document as follows:
• Contain the contaminated soils at the source areas to prevent direct contact by potential human and
environmental receptors, reduce percolation and intrusion of storm water and reduce migration of
compounds of concern ("COCs") into the groundwater. COMPLETED — through the approved
Closure Activities on the Seaboard Site and Former Riverdale Drive Landfill. Seaboard Group I
conducted closure activities at the Facility in 1990 and 1992, during which time the waste materials
in surface tanks and equipment, as well as the empty tanks and process equipment, were cleaned and
removed from the property. In February 1993 NDEQ Hazardous waste division issued approval of
Phase I of the Site Closure. The approved Post Closure Plan for the Riverdale Drive Landfill is dated
April 1994.
• Control migration of landfill leachate to prevent discharge to surface water at the Site. ONGOING —
Active leachate collection is part of the extraction and treatment systems.
• Control migration of contaminated groundwater at the site to prevent offsite migration and
unacceptable impacts to surface water. ONGOING — The remedy has been designed to reduce
migration of impacted groundwater and to collect contaminated groundwater from strategic locations
11

to prevent migration off Site and/or discharge to surface water. The work identified in TM- 11 is being
evaluated as a means to further support this corrective action.
Achieve compliance with North Carolina surface water quality standards for the COCs in the surface
water of the onsite streams. ONGOING — Fluctuations in COCs concentrations in surface water
samples has led to additional corrective measures and further evaluation of additional extraction
locations.
Achieve compliance with North Carolina groundwater quality standards for the COCs in the
groundwater beneath the Site. ONGOING — Progress has been made, but additional evaluation
and implementation of the remedial process is necessary to achieve this objective.
Restrict future Site uses that could present potentially unacceptable exposure risks (e.g., residential
development, use of impacted groundwater, etc.). COMPLETED — Land Use Restrictions (LURs)
are in place for the three properties; Seaboard Chemical, Riverdale Drive Landfill, and the Materials
Recycling Facility (MRF). Annual Certifications are provided confirming details of the LURs are in
place.
IV. FIVE-YEAR REVIEW PROCESS
Data Review
The FYR included a review of relevant Site documents, monitoring data, and operational data with a focus
on operational data collected in the five-year period from August 2017 through August 2022. A review
of findings and data trends for groundwater are included in this section. Time -series graphs showing
monitoring data trends in wells are discussed below. Surface water data for this reporting period is
tabulated below. The groundwater and surface water data were collected and summarized in annual
monitoring reports previously submitted to NCDEQ. Operational data generated as part of on -going long-
term remedial action activities were summarized and included in progress reports submitted on a quarterly
basis.
The Remedy was designed to capture and extract contaminated groundwater and leachate from select
locations along the northern portion of the Site (referred to collectively herein as the "extraction network").
As reported in the 2022 Groundwater Monitoring Report, the collection system has been successful in
retaining contaminated groundwater on Site. Analytical data indicate the extraction and treatment systems
are effective at controlling groundwater contamination migration from the Site.
A review of groundwater and surface water monitoring results over the past five years indicates a
declining trend in COC concentrations. The contaminant trends in groundwater have been plotted for the
past ten years to show this trend and establish the background COC concentrations prior to full-time
operation of the treatment system. Note that the treatment system was in operation on an intermittent
basis beginning in 2013/2014 prior to the official startup date in August 2017. The effect of this earlier
extraction operation is evident from the trend graph plots. A discussion of this data for each of the
media types is provided below:
Groundwater Data
Groundwater analytical data for the past ten years have been summarized for total volatile organic
compounds (VOC) and 1,4-dioxane. The COC trend graphs for these compounds are provided in Figures
4 and 5. Please note the variation in the scale of the y-axis for these graphs, which is significant at some
locations.
12

VOC Trend Graphs
The concentration trend of VOCs on Figure 4 indicates significant COC reduction in monitoring
wells MW-3C, PW-5D, PW15D, and PW-16D. These monitoring wells are all within the capture
zone of the primary extraction well PW-DR1. These trends indicate the capture zone created by
the PW-DR1 is controlling groundwater flow and preventing further off -site COC migration. The
noted reduction in COC concentration is related to dewatering of the shallow bedrock aquifer and
the introduction of less contaminated water.
The VOC contaminant trend in monitoring well W-4A, located downgradient of the former
Seaboard Site, shows a similar COC reduction from groundwater extraction operations. Shallow
extraction well RW-SIS2 is located immediately adjacent to monitoring well W-4A and has
lowered the groundwater elevation by 10' since operation began.
Groundwater monitoring well MW-15A is located immediately downgradient of the Soil Residue
Mound (SRM) and is outside of the influence of any of the extraction wells. The VOC trend in
this monitoring well shows an overall downward trend confirming the remedial approach to cap
the SRM in 2010. The synthetic cap was installed to reduce rainfall infiltration and the generation
of leachate from the waste mass.
The VOC data plot for monitoring well PW-3D does not show a clear trend. This well, located
between the former Seaboard Site and the Landfill, has been outside of the influence of the
groundwater extraction system until the recent TM- I I work which is currently being evaluated.
This well is also located hydraulically downgradient of the former Pond 3.
1,4-Dioxane Trend Graphs
The COC data graphs for 1,4-dioxane follow a similar trend noted with the VOC graphs (Figure
5). The COC concentrations in the monitoring wells near the primary extraction well PW-DR1
show a significant reduction in 1,4-dioxane concentration. This data indicates dewatering of the
shallow bedrock.
Monitoring well W-4A has also shown a decreasing 1,4-dioxane trend due to its proximity to
groundwater extraction well RW-SIS2. The continued operation of the expanded extraction
associated with TM -I I should also assist to improve the groundwater quality at this location.
The 1,4-dioxane trend in monitoring well MW-15A, located downgradient of the SRM, shows a
steady decrease in COC concentration. As discussed earlier, this is likely due to the installation
of the synthetic cap which serves to reduce rainfall infiltration and the generation of leachate.
The 1,4-dioxane concentration trend in PW-31) is increasing, however, the overall 1,4-dioxane
concentration is relatively low and it is anticipated that the continued operation of the TM -I I
extraction wells located immediately upgradient of PW-31) should improve this trend.
Surface Water Data
Surface water samples are collected annually at several locations across the Site and on Randleman Lake
(Figure 2). The surface water samples collected on Randleman Lake are collected at two discrete depths:
1' below the surface and V above the bottom of the Lake. A brief description of the sample locations is
provided below:
13

Northern Intermittent Stream (NIS) — Samples SW-1 and SW-2
Southern Intermittent Stream (SIS) — Samples SW-3, SW-4, and SW-5
Randleman Lake — Samples SW-6, SW-DRP2, SW-7, and SW-DRPI I
Surface Water VOC Data
The laboratory analytical data for surface water samples collected from the Northern Intermittent
Stream (NIS) and Randleman Lake (surface and bottom samples) did not identify appreciable
concentrations of VOCs over the initial 5 years of remedial system operation. Note that the NIS
has a limited watershed area, and the sample locations are frequently dry.
The upper SIS samples have shown occasional single -digit detections of VOCs, especially in
surface water sample SW-3. The SW-3 surface water sample location is hydraulically
downgradient of the former Seaboard Site. The VOC concentrations in these samples are
significantly lower than observed prior to the operation of the remedial system. Pre -remedial VOC
concentrations at the SW-3 location ranged from 100 ug/l to 200 ug/l prior to operation of the
shallow extraction wells at the upper SIS area.
The VOC results for the lower SIS sample (SW-4) has shown a highly variable COC concentration
over the past 5 years. This variation is attributed to rainfall patterns and groundwater contribution
to the SIS.
Surface Water Samples - 1.4-Dioxane Concentrations
Sample ID
10/2017
11/2018
9/2019
10/2020
10/2021 10/2022
Northern Intermittent Stream Samples
SW-1
Dry
12 ug/1
BQL
Dry
Dry
Dry
SW-2
BQL
22 ug/1
BQL
Dry
Dry
14 ug/1
Randleman Lake Samples
SW-6(S)*
13 ug/1
BQL
1.6 ug/1
BQL
BQL
BQL
SW-6(B)*
14 ug/1
BQL
BQL
BQL
BQL
BQL
SW-DRP2(S)
19 ug/1
BQL
1.4 ug/1
0.83 ug/1
BQL
BQL
SW-DRP2(B)
21 ug/1
BQL
BQL
BQL
BQL
BQL
SW-7(S)
26 ug/1
BQL
BQL
BQL
BQL
BQL
SW-7(B)
20 ug/1
BQL
BQL
BQL
BQL
BQL
SW-DRP11(S)
31 ug/1
BQL
1.3 ug/1
BQL
1.4 ug/1
1.0 ug/1
SW-DRPI I(B)
31 ug/1
BQL
BQL
BQL
1.2 ug/1
BQL
Upper Southern Intermittent Stream Samples
SW-5
14 ug/1
23 ug/1
5.8 ug/1
3.5 ug/1
2.2 ug/l
1.6 ug/1
14

SW-3
9.7 ug/1
13 ug/t
1.7 ug/1
3.9 ug/l
4.6 ug/1
2.1 ug/1
Lower Southern Intermittent Stream Sample
SW-4
1,700 ug/l
48 ug/l
1,800 ug/l
79 ug/l
1,500 ug/l
14 ug/l
Randleman Lake Samples: (S)=Shallow sample; (B)=Bottom sample
* Upgradient background samples
Surface Water 1,4-Dioxane Data
The laboratory analytical data for surface water samples collected from the NIS reported detectable
concentrations of 1,4-dioxane in samples collected in 2018 and 2022. These detections appear to
be attributed to above -average rainfall and runoff from the phytoremediation zones at the time of
sample collection.
The surface water samples from Randleman Lake (1' below surface and 1' above bottom samples)
reported concentrations of 1,4-dioxane in all samples during the initial startup of operations (2017).
Since that time, the concentrations have been minor and may be attributed to background sources.
Note that surface water sample SW-6 is located 3,500' upstream of the Site and provides
background surface water quality.
Randleman Lake surface water sample SW-DRP 11 is located 4,100' downstream of the Site at the
confluence of Richland Creek. At least two known sources of 1,4-dioxane in surface water are
located on Richland Creek upstream of this confluence.
The upper SIS samples have shown a significant reduction in the 1,4-dioxane concentration over
the initial 5-year operational period. The operation of the three shallow extraction wells (RW-
SIS2, RW-SIS3, and RW-SIS4) along the upper SIS has resulted in an improvement of surface
water quality.
The 1,4-dioxane results for the lower SIS sample (SW-4) have shown a highly variable
contaminant concentration over the past 5 years of operation. This variation is attributed to rainfall
patterns and groundwater contribution from the SIS drainage channel.
Operational Data
The information provided in this report includes five years of monitoring following the NCDEQ's
approval of the construction of the remedy, August 25, 2017 through August 2022. This information is
essentially a summary of the data that has been previously reported to the department in the form of
Quarterly Progress Reports, including the 3rd Quarter 2017 through the 3rd Quarter 2022.
Several operational issues were encountered that required modifications to the system throughout this
five-year period. Summaries are provided below:
• February 2018 — Hazen & Sawyer re-evaluated Mechanical System, recommended additional air
sparging prior to clarifier and chemical dosing modifications.
• Spring 2018 —New air sparge tank installed prior to clarifier to enhance metals removal. Installed
surge suppressors to protect treatment system components from lightning strikes and other
15

electrical spikes.
• December 2018 — Replaced fiber optics cable from LS-1 to primary treatment building.
• Summer 2019 — Removed AOP+ (PhotoCat) system from LS-2 treatment enclosure for recycling.
• October through December 2019 — Major upgrade of PLC/HMI control systems.
• Summer 2020- Spring 2021 — Evaluated the SIS corridor by way of video, pump tests, dye
tracing, new monitoring well installations.
• Summer 2020 — Summer 2021 — Continued fertigation of the entire phyto system along with
tissue sampling to ensure proper nutrient levels within the Natural System.
• September 2021 — Hazen & Sawyer re-evaluated the mechanical treatment system for the
addition of the new extraction wells along the SIS corridor as described in TM-11. New chemical
dosing setpoints were recommended along with the installation of a soda ash feed system.
• Fall 2021 — Winter 2022 — A new plug was installed at the upper end of the NIS collection pipe
along with regrading of areas of ponding water along the route to reduce inflow and infiltration
of clean surface water into the collection system.
• Fall 2021 — Planted 400 additional trees to fill in bare areas of the phyto zones and other areas of
seepage.
• Fall 2021 — Replaced and repositioned two lysimeters.
• Spring 2022 — Installed new soda ash feed system per Hazen recommendations.
• Summer 2022 — Plumbed in two new wells and two existing wells along the SIS corridor into the
extraction system per TM-11.
• Summer 2022 — Rovisys integrated the soda ash feed system and new wells into the PLC system
and added priority programming for source points.
• Summer 2022 - Fall 2022 — Redesigned the twenty-four miles of drip lines and purchased
materials for the wholesale replacement of existing lines. Installation is scheduled to be done in
the Winter of 2022-2023.
• Summer 2022-Winter 2022 — Evaluated and tested a new radio network for transmitting well
transducer levels to the PLC. Installation is in progress.
• Ongoing — Replacement of collection system pumps to higher capacity pumps. The majority of
extraction pumps have been changed to higher capacity pumps based on monitoring activities,
mostly because of higher precipitation and leachate collection.
In addition, there were many shorter duration modifications / optimizations completed throughout the 5-
year reporting period. These modifications are presented on the following table:
Issues Encountered
Date
Resolution
Frozen chemical feed lines and
Added heat trace and/or insulation to
•
irrigation control valves
18-Jan
lines
• Electrically damaged communication
18-Feb
Added surge suppression on low
I/O cards
voltage lines
• Intermittent power failures
18-Feb
Added low voltage UPS devices
• Scaling of pumps and process lines
18-Mar
Modified chemical feed rates and
se uestrant type per Hazen report
• Scaling of pumps and process lines
18-May
Installed air sparge tank prior to
clarifier
• Intermittent communication loss
18-Dec
Replaced fiber optic cable from LS-2 to
LS-1 and the node buildings
16

Scaling of pump lines from LS-1 and
Re -piped the force mains in LS-1 to
0 LS-2
18-Dec
allow individual citric washes while in
operation
LS-1 compressor failed due to water
Replaced LS-1 compressor and wired
0 build-up from unloading
18-Dec
LS-2 compressor for temporary back-
up
• Intermittent communication loss
19-Jan
Replaced Profibus connections
0 Pressure loss at LS-1 compressor
19-Jun
Replaced pneumatic pumps, valves,
and regulators
a Clogged sludge lines
19-Oct
Replaced sludge pumps and re -piped
manifolds
• Continual communication losses and
19-Oct
Replaced all drives, communication
lack of replacement parts
I/O racks, HMI's and PLC
• Filter Building (FB) compressor
20-May
Tied air lines to LS-2 compressor and
frequent failures
eliminated small FB compressor
•
Replaced pump and motor with one
PWDR-1 motor failure
21-Jul
more properly sized for current
operational parameters
• Ongoing issues with LS-1 and LS-2
22-Feb
Installed oil -mist separators and purge
compressors
lines to increase load time
•
Replace hydraulic seals, installed
Sludge drying box hydraulics failure
22-May
additional grease fittings, increased
pressures
0 Clarifier cone and chemical feed failure
22-Aug
Replaced supports and fee connections
with higher resistance materials
•
Replaced screens and placed additional
Sludge drying box loss of efficiency
22-Aug
cleanings on an annual maintenance
schedule
As presented, modifications were implemented throughout this reporting period. With the difficulties
encountered, the overall system run time has been calculated to be 74% during this reporting period.
System run time has increased significantly following completion of the ongoing modifications listed
above. As shown below:
17

100.0%
90.0%
80.0%
70.0%
a 60.0%
30.0%
20.0%
10.0%
0.0%
System Run-time % & Average Flow
r- n 00 CO CO CO 07 07 Q7 Q7 O O O O N N
N N N N N N N N N N N 0 C 0 0 0 C 0 CD 0 0 O O O O O O O O O O O
N N N N N N N N N N N N N N N N N N N N N
ro t rl N M It r-I N ro -It 1-1 N rn �* 1- N ro It N M
a a Cr a a a Cr a a a a a a a a a a a a a a
50.0
45.0
40.0
35.0
7.
a
30.0 U
15.0 Q
10.0
5.0
0.0
fRun-time(%) fAverageFlow (GPM) ......••• Linear (Run-time(%)j ......••• Linear (AverageHow (GPM))
The trend for the run-time percentage has continued upward over the 5-year period. Dips in the runtime
are due to system modifications such as the PLC control network replacement in Q4 2019. The trend for
the average system flow has stayed steady over the review period. As contaminated aquifers are de -
watered, extraction levels have been lowered and additional source points have been brought online to
maximize the system resources.
The influent flows have varied over the course of the review period. Variations in the flow are due to
seasonal changes such as rainfall, operating efficiencies, and de -watering of certain areas. Due to
increased efficiencies of the system, larger extraction pumps, and additional flow sources, the amount of
water processed has generally increased. The chart below illustrates the total processed flow vs. the
various extraction sources:

5,000,000
= 4,500,000
w
Q 4,000,000
3,500,000
LL
w
N 3,000,000
z
O 2,500,000
2,000,000
1,500,000
1,000,000
500,000
0
Flow Comparison
r- r- c0 00 00 00 a) a] a) 07 O O O O r-I r-I r-I r-I N N N
r-I r-I r-I r i r-I r-I r-I rl r-I r-I N N N N N rIj N N N N rIj
O O O O O O O O O O O O O O O O O O O O O
N N N N rIj N N N N rIj N N N N N rq N N N N rIj
ro �t rl N rn �t r-I N rf) * r-I N M �t 1- rIj M �* 1- N M
a a a a a a a a a a Cr Cr Cr a a Cr a a a a Cr
f LEACHATE (GALLONS) f LS1-RWs (GALLONS) --&-- PWDR1 (GALLONS)
f SIS-RWs (GALLONS) —0— PHYTO DISCH. (GALLONS) ......••• Linear (LEACHATE (GALLONS))
......••• Linear (LS1-RWs (GALLONS)) ........ Linear (PWDR1 (GALLONS)) ......••• Linear [SIS-RWs (GALLONS)]
......••• Linear (PHYTO DISCH. (GALLONS)}
The processed water from the shallow recovery wells at LS 1 and SIS has increased during the entire period
due to larger extraction pumps, additional sources, higher run-times, and increased precipitation. The
amount of leachate processed has increased due to larger extraction pumps, higher run-times, and
increased precipitation. PWDR-1 production has decreased over the review period, even though pumping
elevations have been lowered, as the aquifer is dewatered. The overall result shows a general increase in
total production through the system.
19

A breakdown of the amount of flow from each of the individual source points over the 5-year review
period is detailed in the table below:
MATED INDIVIDUAL SOURCE VOLUMES (2017-2022)
TOTAL
AVG. GALLONS
% OF TOTAL
% OF
GALLONS
PER MINUTE
FLOW
GROUP
PWDR1
24,952,443
10.7
34.4%
% OF GROUP
LCHT-1*
203,501
0.1
0.3%
1%
LCHT-2
4,787,621
2.1
6.6%
18%
LCHT-3
563,432
0.2
0.8%
2%
LCHT-4
1,694,953
0.7
2.3%
6%
LCHT-5
6,315,118
2.7
8.7%
24%
LCHT-NIS1
6,815,507
2.9
9.4%
26%
LCHT-NIS2
5,860,026
2.5
8.1%
22%
26,240,158
11.3
36.1%
100%
RW-NIS
8,051,605
3.5
11.1%
55%
RW-LFS1*
3,566,640
1.5
4.9%
24%
RW-LFS2
2,188,461
0.9
3.0%
15%
RW-SIS1*
949,128
0.4
1.3%
6%
14,755,834
6.3
20.3%
100%
RW-SIS2
1,885,197
0.8
2.6%
31%
RW-SIS3
2,373,984
1.0
3.3%
39%
RW-SIS4
1,778,122
0.8
2.4%
29%
6,037,303
2.6
8.3%
100%
CITRIC/RAIN/TANK FILL
179,908
0.1
0.2%
BACKWASH
442,062
0.2
0.6%
621,970
0.3
0.9%
* INOPERATIVE PUMP COUNTERS SKEW SOME RESULTS
72, 607, 708 31.2 100%
20

Influent concentrations to the system gradually decreased over the 5-year review period indicating an
effective remedy in the areas of treatment. In order to further prevent COC migration through the SIS
corridor, recovery wells RW-SIS7, RW-SIS8, R-1, and PWSF-1 were brought online in the summer of
2022 as detailed in TM-11. The resulting influent COC concentrations increased immediately. These
events are illustrated in the chart below (note the 1 Ox concentration difference between the left and right
vertical axis):
VOCs & 1,4-D Concentrations
22,500
20,000
17,500
15,000
o�
12,500
z
w
J 10,000
z
7,500
5,000
7..500 _
0 -
61
IV �O .tip T ti0 y0 ti� 1ti 1ti IV 1� 1� T IV tiV T T ti0 �O ti61ti
6? C� Cti Cti 03 C� Cv 01 0 C� C~ 01 C3 Coy Cti OV C3 C3
f1NFLUENTVOCs(ug/L) fEFFLUENTVOCs(ug/Q
21
2,500
2,250
2,000
J
1,750 nod
1,500 Q
c-i
1,250
H
1,000 z
LU
750 LL
U-
w
500
250
0
—0--1,4-DIOXANE (ug/L)

Due to the increase in the amount of water processed, the increase in run-time, and the increase in removal
efficiency, the total VOC mass destruction from the Mechanical System has generally increased as well
over the review period, even though influent concentration decreased over that same time. Once the
additional recovery wells were brought online in the summer of 2022, the mass destruction rate increased
dramatically. The total mass of VOCs removed by the Mechanical System during the initial 5-year
operating period is 1346 Kg (2967 lbs). The results are illustrated in the chart below:
300.0
275.0
250.0
d
225.0
200.0
a
Z 175.0
�a 150.0
0
0
E 125.0
a�
N 100.0
N
2 75.0
50.0
25.0
0.0
Mechanical System - VOC Mass & % Removal
rn rn m m co 0o rn m rn rn O o O O 14 14 1-4 14
1l �A �A rA r A 1l N N N N N N N N
O O O O O O O O O O O O O O O O O O
N N N N N N N N N N N N N N N N N N
rn rl N rn -t N M �t N n1 -* r A N rn tll
a d d a d a a a a a a Or d a d d
t MECHANICAL MA55 VOC RE MOVAL (kg) --0— MECHANICAL VOC REMOVAL %
......••• Linear (MECHANICAL VOC REMOVAL %)
N N N
O 0 0
N N N
N rn
a Cr Cr
100%
99%
98%
97%
96%
95%
0
94% E
93% y
M
92%
91%
90%
89%
88%
The Natural System received and processed approximately 72 million gallons of irrigation water from the
Mechanical System. The irrigation system consists of 16 individual zones which comprise a total of 32.5
acres.
The mass of VOCs and 1,4-dioxane removed by the Natural System is determined by a comparison of the
influent concentration from the Mechanical System and the effluent concentrations determined from
samples collected from the lysimeters installed in various irrigation zones. The total mass of additional
VOCs and 1,4-dioxane removed during the initial 5-year operating period is 18 kg (40 lbs.) and 179 kg
(395 lbs) respectively.
22

The percent of COC removal is based on the calculated water balance for the natural treatment area which
takes into account the following parameters:
• Irrigation water applied to the 32.5 acre treatment area
• Daily rainfall measurements
• Rate of water use by the tree stand
• Interception (rainfall caught by the needles of the trees and evaporated)
• Overland Flow or Runoff
The Natural System has shown a consistent removal pattern over the 5-year review period. The remaining
VOC's removal by the Natural System results in a 99.97% total overall removal for the entire 5-year
period. The Natural System has also been able to achieve over a 94.3% 1,4-dioxane removal during the
same period. These results are illustrated in the charts and table below:
100
90
80
(V
r- 7,0
m
ti 60
Y
5.0
0
4.0
VI
M 3.0
20
1,0
00
Natural System - VOC Mass Removal & Total System - VOC % Removal
I� r• CO CO CO Co a) 07 G7 a) C O C O -4 N N N
rl rl N N N N N N N N N N N
O C C O O O O O O O C O O C C C C O C O O
N N N N N N N N N N N N N N N N N N N N N
M �r ri N M -t r-1 N M It r-1 N M �t ri N M It ri N M
f NAT. SYSTEM MASS VOC REMOVAL ft) ♦TOTAL SYSTEM VOC % REMOVAL
......••• Linear (TOTAL SYSTEM VOC %REMOVAL)
23
100,0%
99.9%
99.8% F
99.7%
0
99.6%
VI
99.5%
99.4% y
a
99.3%
99.2% 0
99.1%
99.0%

Natural System - 1,4-Dioxane Mass & % Removal
20
100.0%
18
...........
90 0%
16
80.0%
14
70.0%
m
e
12
60.0%
bb
Y
0
Fa 10
50 0% E
>
0
o
8
40.0% rc
y
y
6
—
30.0%
4
20.0%
2
10 0%
0
0.0 %
1,
n
00
CO
00
00
07
07
Q7
Q7
O
O
O
O
N
N
N
rl
O
CD
O
rl
O
CD
O
CD
O
rl
O
CD
O
CD
O
O
O
O
O
O
O
O
O
O
O
O
O
O
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
M
rl
N
fM
zt
rA
N
fM
-zt
.--I
N
rn
rl
N
fM
rl
N
M
cr
cr
a
a
a
cr
cr
cr
cr
cr
a
ct
a
a
cr
cr
a
a
a
rr
a
f 1,4-❑IOXANE MASS REMOVAL (kg) f 1,4-❑IOXANE REMOVAL % ......••• Linear (1,4-DIOXANE REMOVAL %)
MASS DESTRUCTION DETAILS (2017 Q3 - 2022 Q3)
MASS REMOVAL
REMOVED (kg) EFFICIENCY (%)
VOC's
MECHANICAL SYSTEM 1346 98.7%
NATURAL SYSTEM 18 97.5%
TOTAL VOC's 1364 99.97%
1,4-DIOXANE
NATURAL SYSTEM 179 94.3%
OVERALL SYSTEM TOTAL 1543 99.3%
WE

Site Inspection
The inspection of the Site was conducted on 2/15/2023. In attendance were Eric Aufderhaar, Joshua
Hanks, and Dan Girdner, NCDEQ, Robby Stone, Melinda King, and Mike Spencer City of High Point,
and Gary Babb, Babb and Associates, Rich Glover, Glover Engineering, Craig Coslett, de maximis, and
Bruce Braswell, Trustee. The purpose of the inspection was to assess the protectiveness of the remedy.
Participants of the Inspection met at the Treatment facility located at Recovery Way before Inspecting the
various components of the Remedy using vehicles to traverse the Site. The FYR Inspection included the
routine annual site inspection conducted by the NC Hazardous Waste Section due to the former Seaboard
Chemical's status as a treatment, storage, or disposal facility.
V. TECHNICAL ASSESSMENT
QUESTION A: Is the remedy functioning as intended by the decision documents?
YES - The remedial actions summarized above in Section II — Response Action Summary have been fully
implemented and operate on a continuous basis. Numerous upgrades to the system have been evaluated
and incorporated into the treatment system as described in the Status of Implementation section of this
report.
Surface water COC levels have been reduced due to the operation of the extraction system and
contaminant levels are consistently at or near standards and or target values. Groundwater COC levels
have also been significantly reduced as the extraction systems have outpaced COC recharge from the
source areas. Further expansion of the extraction system, as provided by TM-11, will enhance
containment of COC migration and improve mass removal near the source areas.
The capture zones created by the extraction systems are controlling the majority of the contaminant plume
in the SIS watershed. Additional evaluation is ongoing to determine the effectiveness of the expanded
shallow aquifer extraction system at the SIS Basin Area and the shallow bedrock extraction system at the
Pond 3 Area. These two new extraction areas are being evaluated quarterly for 1 year. The first two
quarterly evaluation reports of these systems had been submitted to the NC DEQ at the time the 5YR
Report submittal.
Improvements are also underway to replace the irrigation lines in the phytoremediation zones which will
better balance flow to each zone, tailor the irrigation flow based on past operational observations, and
allow for easier inspection and maintenance of the irrigation system.
The institutional controls implemented at the Site, primarily security fencing around the entire site and
land use restrictions, have been effective in preventing exposure to contaminated soil, waste residues, and
treatment operations. No unauthorized access to the Site has been reported during the 5-year operational
period.
25

QUESTION B: Are the exposure assumptions, toxicity data, cleanup levels, and remedial action
objectives (RAOs) used at the time of the remedy selection still valid?
YES - The exposure criteria at the Site have not changed significantly over the 5-year operating timeframe.
The COCs have not varied from the original assessment work performed at the Site; however, the
concentration of the COCs has decreased during the 5-year operational period. This overall reduction in
COC concentrations improves the exposure potential for workers at the Site. Also, the institutional
controls implemented prior to full operation of the treatment system have prevented exposure from
unauthorized personnel.
Regulatory standards and guidance have changed since the effective date of the RASA in 2008. Both
groundwater and surface water standards are periodically updated based on the most recent available
toxicological data. The most recent update to these standards occurred in 2022. A summary of the updated
groundwater and surface water regulatory standards for the COCs at the Site is provided below:
Comparison of Groundwater Standards
Compound Name
Original Standard *
Current Standard **
1,1,2-Trichloroethane
No Standard
0.6 a /l
1, 1 -Dichloroethane
700 a/1
6 u /1
1,1-Dicloroethene
7 u /1
350 a/1
1,2-Dichloroethane
0.38 u /1
0.4 u /1
1,2-Dichloro ro ane
0.56 u /1
0.6 u /1
1,4-Dioxane
7 u /1
3 u /1
Acetone
700 a/1
6,000 u l
Chloroethane
2,800 u 1
3,000 u 1
Chloroform
0.19 u /1
70 u /1
Eth lbenzene
29 u /1
600 u /1
Toluene
1,000 u 1
600 a/1
trans-1,2-Dichloroethene
70 a/1
100 a/1
Trichloroethene
2.8 u /1
3 u /1
Vinyl Chloride
0.015 u 1
0.03 u /1
X lenes (Total)
530 a /1
500 a/1
* Standard at the time of signing RASA (2008)
** As of January 2023
Comparison of Surface Water Standards
Compound Name
7-original Standard *
Current Standard **
1,1,2-Trichloroethane
200 a/1
2,500 u 1
1, 1 -Dichloroethane
42 u /1
6 u /1
1, 1 -Dicloroethene
0.057 u 1
300 u /1
1,2-Dichloroethane
0.38 a/1
9.9 a/1
1,4-Dioxane
3 u /1
0.35 u /l ***
Acetone
350 u /1
3,100 u 1
Chloroethane
860 u /1
NE
cis-1,2-Dichloroethene
33 u /1
60 u /1
Methylene Chloride
4.7 a/1
11,000 a/1
Tetrachloroethene
0.8 a/1
0.7 a/1
trans-1,2-Dichloroethene
700 u /1
290 u /1
Trichloroethene
3.08 u /1
2.5 u /1
Vin l Chloride
2 u /1
0.025 u 1
26

X lenes Total
88.5 a /l
6,200 u 1
2-Butanone
2,090 u 1
20,000 u /1
NE — Not Established
* Standard at the time of signing RASA (2008)
** As of January 2023
*** Not a regulatory standard but an In -Stream Target Value
While several of these updated standards represent significant changes, they are not expected to affect the
current remedial action at the Site. The Mechanical System and Natural System have been designed to
address the concentration of VOCs and 1,4-dioxane present at the Site. As this is a containment remedy,
continued groundwater and surface water monitoring is necessary to evaluate the effectiveness of the
groundwater extraction systems. Continued monitoring, evaluation and modification (when applicable)
to the extraction and treatment systems will improve the efficacy of the remediation and further improve
water quality at the Site.
QUESTION C: Has any other information come to light that could call into question the protectiveness
of the remedy?
NO - As provided in this report, frequent modifications/improvements to the mechanical and natural
treatment systems, extraction systems, groundwater and surface water monitoring, and
operation/maintenance have occurred over the 5-year operational period. These
modifications/improvements were implemented to increase the effectiveness of the overall remedial
system to meet the objectives of the RASA. Any limitation identified in the remedial system has been
proactively addressed in a timely manner.
VI. ISSUES/RECOMMENDATIONS
Issues and Recommendations Identified in the Five -Year Review:
Issue Category: Monitoring
Issue: Detectible COC concentrations in on Site Surface water (NIS) during
periods of heavy precipitation.
Recommendation: Increase monitoring to quarterly to evaluate NIS surface
water conditions following replacement of irrigation lines in the
phytoremediation areas.
Affect Current
Affect Future
Party
Oversight Party
Milestone Date
Protectiveness
Protectiveness
Responsible
Yes
Yes
PRPs
State
l/l/2025
The laboratory analytical data for surface water samples collected from the NIS reported detectable
concentrations of 1,4-dioxane in samples collected in 2018 and 2022. These detections appear to be
attributed to above -average rainfall and runoff from the phytoremediation zones at the time of sample
collection.
27

Replacement and balancing of the irrigation lines in the phytoremediation zones is scheduled to be
completed in 2023. It is anticipated that this work will minimize runoff.
Issue Category: Monitoring
Issue: Fluctuating COC concentrations in on Site Surface water (SIS)
Recommendation: Complete TM-11 Evaluation / Increase monitoring of
select surface water locations in the SIS to quarterly.
Affect Current
Protectiveness
Affect Future
Protectiveness
Party
Responsible
Oversight Party
Milestone Date
Yes
Yes
PRPs
State
1/1 /2024
The upper SIS samples have shown a significant reduction in the 1,4-dioxane concentration over the initial
5-year operational period. The operation of the three shallow extraction wells (RW-SIS2, RW-SIS3, and
RW-SIS4) along the upper SIS has resulted in an improvement of surface water quality. However, the
1,4-dioxane results for the lower SIS sample (SW-4) has shown a highly variable COC concentration over
the past 5 years of operation. This variation is attributed to rainfall patterns and resultant flow in the SIS.
The impact of additional extraction wells located in SIS basin on surface water quality at the SW-4
location is currently being evaluated as part of the TM -I I study. Quarterly monitoring and evaluation of
the SW-3 and SW-4 locations is recommended to supplement that study.
Issue Category: Monitoring
Issue: Potential Impacts from other sources.
Recommendation: Eliminate downgradient surface water sample collection
from SW-DRPII locations from future sampling events
Affect Current
Protectiveness
Affect Future
Protectiveness
Party
Responsible
Oversight Party
Milestone Date
No
No
PRPs
State
8/31/2023
Surface Water monitoring station S W-DRP 11 is located 4,100' downstream of surface water monitoring
station SW-7 at the confluence of Randleman Lake and Richland Creek. There are two known sources of
1,4-dioxane surface water contamination in the Richland Creed watershed, located between 2 and 3 miles
upstream from the Randleman Lake confluence. Surface water concentrations of 1,4-dioxane as high as
21 ug/l have been documented downstream of these two known sources. The collection of surface water
samples at the SW-DRP1 Ilocation does not provide representative samples of water quality downstream
of the Seaboard/Riverdale Drive Landfill Site.

Issue Category: Remedy Performance
Issue: COCs in groundwater below the Site
Recommendation: Continue Implementing the Remedial Action
Affect Current
Protectiveness
Affect Future
Protectiveness
Party
Responsible
Oversight Party
Milestone Date
Yes
Yes
PRPs
State
2/29/2028
The selected remedy is operating as designed and as demonstrated by the data collected over the initial 5
years of system operation is effective at controlling the migration of Site COCs downgradient of the Site.
Evaluation of COCs in groundwater below the Site will continue.
VII. PROTECTIVENESS STATEMENT
Protectiveness Determination:
Protective
Planned Addendum
Completion Date:
N/A
Protectiveness Statement: The Remedy is protective of human health and the environment. The
immediate threats were addressed through separate removal and closure activities at the
Seaboard Chemical Property and Former Riverdale Drive Landfill Sites. Effective measures
to address the remedial action objectives have been constructed and are currently being
implemented and monitored.
VIII. NEXT REVIEW
The next five-year review report for the Seaboard Chemical/Former Riverdale Drive Landfill Site is
required five years from the completion date of this review and is anticipated to be February 2028.
29

APPENDIX A — Reference List
• 2017 Construction Completion Report
• Remedial Recommendation Document
• Remedial Monitoring and Effectiveness Evaluation Report, 2022
• Quarterly Progress Reports (2017 through 2022)
• Weekly O&M Log Reports
• Annual Groundwater and Surface Water Monitoring Reports, (2018, 2019, 2020, 2021, and
2022)
kro

APPENDIX B — Sample Copy of Weekly Log Checklist
31

WEEKLY LOG WEEK: TO
SEABOARD GROUP II & THE CITY OF HIGH POINT
METER READINGS:
LS1 LEACHATE
LS1 RWs
PWDR1
SIS RWs
PHYTO DISCH.
POTW DISCH.
AIR STRIPPER
LS1 COMPR. (d1)
LS1 COMPR. (d4)
LS2 COMPR. (d1)
LS2 COMPR. (d4)
ELECT. METER
WATER METER
BACKWASH
SPARGE BLOWER
RAIN GAUGE
(WEEKLY READING)
CHEMICAL LEVELS
SULFURIC ACID
SODIUM HYD.
WATER-WORX
FLOCCULANT
LIME SLURRY
FERRIC CHLORIDE
CITRIC ACID (LBS.)
SODA ASH (LBS.)
SODA ASH (GAL.)
ID
FIT-122
FIT-123
FIT-212
FIT-213
FIT-400C
FIT-400 D
B-605
AC-120
AC-120
AC-200
AC-200
HP-EM
HP-WM
FIT-603
B-600
RG
GALLONS):
T-303
T-304
T-614
T-615
T-711
T-712
WARE.
WARE.
T-713
SOURCE WATER:
(CIRCLE APPLICABLE SOURCES)
COMMENTS:
READING
UNITS
GAL
GAL
GAL
GAL
GAL
GAL
RUN HRS
RUN HRS
LOAD HRS
RUN HRS
LOAD HRS
EFFLUENT
LAB SAMPLE
PWDR-1 SIS RWs LS1 RWs LS1 LCHT
DATE
BY
WELL
LEVELS
OWDR-4
OWDR-2
PWDR-1
OWDR-3
PW-6D
OWLFS-2
PW-16D
PW-15D
LAKE
PUMP
LCHT-1
LC H T-2
LCHT-3
LC H T-4
LCHT-5
LCHT-NIS1
LCHT-NIS2
RW-NIS
RW-LFS1
RW-LSF2
RW-SIS7
RW-SIS8
RW-SIS2
RW-SIS3
RW-SIS4
R-1
PWSF-1
(DATE, TIME ARRIVED, TIME DEPARTED, PERSONNEL ON SITE, TASKS COMPLETE, ISSUES)

CHECKLIST:
(INITIAL ALL THAT APPLY) (DATE)
(2 TIMES PER WEEK)
MON
TUES
WED
THUR
FRI
SAT
SUN
CHECK FLOC QUALITY (2X PER TRIP)
SKIM CLARIFIER
REPLACE LS2 FILTER BAGS
CHECK ELECTRIC PUMPS
CHECK PNEUMATIC PUMPS
(1 TIME PER WEEK)
CHECK CALIBRATION TUBES
CHECK CHEMICAL STORAGE AREAS
TIP DRYING BOX
MOVE DUMPED SLUDGE
CHECK PUMP COUNTERS
REPLACE FB FILTER BAG
CLEAN RAIN BUCKET (NO WATER)
CHECK GAUGES & METERS
CHECK VALVES
CHECK GATES/LOCKS
(MONTHLY)
SAMPLE INF., EFF., & PRE A.S.
GREASE BLOWER (2X PER MONTH)
CHECK BLOWER OIL
CHECK AIR COMPRESSOR OIL
CHECK FIRE EXTINGUISHERS
CHECK EYE WASH STATIONS
PEST CONTROL IN JBZs & BUILDINGS
MOW & LIMB CRITICAL PATHS, BLDGS.
CALIBRATE pH PROBES
CALIBRATE METHANE DETECTORS
CHANGE CITY WATER FILTER
FLUSH HYDRANT AND YARD HYDS.
CHECK FENCE INTEGRITY
CHECK FOR STRESSED VEGETATION
CHECK FOR PONDING WATER
CHECK IRR. CONTROL BOXES
(QUARTERLY)
CHECK FOR CAP SUBSIDENCE
CHECK FOR SLOPE EROSION
CHECK CAP EROSION
CHECK SLOPE DRAINS
CHECK FOR LEACHATE BREAKOUTS
VACUUM PANELS
MOW ALL AREAS
CHECK EACH ZONE FOR LEAKS
SAMPLE TCLP & 8270 (ANNUALLY)
CHANGE AIR FILTERS
CLEAN EXHAUST FANS
INVENTORY SPARE PARTS
CHECK FOR NIS SCOUR
COMMENTS:

FIGURE 1 — Site Location Map
32

- Greensboro
are I
r"
i, wIJ44 l
I ++rr
High Point r" -
� ea a-oard/ rverdaLI Land-61 Site..` f e y
4 ;..
-- - Site Location
.I
I f
Figure 1 — Site Location Map Seaboard Group II
Former Seaboard/Riverdale Drive Landfill Site and
5899 Riverdale Drive The City of High Point
Jamestown, North Carolina
Scale- Prep. By. Rev. By- Date.
1" = 1.5 miles G. Babb G. Babb February 2023

FIGURE 2 — Site Features Map
33

SW-1
Phyto
Zones
1-11
SW-6
.. Located Upstream
�At Kivett Dr. Bridge
SW-2
RW-NIS ENIS Sump
MW-12A!„��
Ob MW-12B
MW-12D PW-14D
SW-DRP2
Igh
lop,
PW-131 MW-3C "POW-DR2
Soil
'd; .LCHT3
Residue
PW-5D , •PW-DR1
M anical Treatment
Mound System LS-2
.................�
ORW-slss
and
ORW-SIS7
LCHT5E ' SW-4
LCHT4
s�SP
MW-15A
SW-3
W-4A191h
SW-5 •RW-SIS2
Igh RW-SIS4� •-SIS3 �� Ai Phyto
PW-SF10 PW-3D PW-41 Zones
12-16
R-1
r
.�"''r' •
N
,k PW-16D
mr
PW-15D
:D
PW-6D
PW-61
LCHT2
RW-LFS20
OW-LFS2
71--1.
PW-10IAOIhMW-10
go
Rw-LFs1 �, PW-10D
LCHT1
SW-7
Q; Groundwater Monitoring Well
Surface Water Monitoring Location
Leachate Collection Tank/Sump
Shallow Groundwater Recovery Well
Deep Groundwater Recovery Well -,
SW-DRP11
Located Downstream
At The Confluence O
Richland Creek

FIGURE 3 — Process Flow Diagram
34

ll —L— IT 1 I F -Li F
Lori LCKr.3 Lcur-a U"-& U>rm ►m,&U.A
LFArMTE OO LECTM TANK8
I 1I -Ltna
RW4191 kW4-F92 aw-ml Rw-ml
44tAuI 4 7 F C"
GRCMNOWATER RECOVERY WELLS
PP-Cf41
fmui
(—Law) MHkLOM { VAL!LO p
M
N
O
N
L
�i
cu
L
• O
CD
LL
O
cz
LIFT STATION 2
V
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FILTER SUILDiNG
L -2
T-am T-001 Fk44
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CIMRER
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FINIYFi
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TAM
TAW
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V
m
Q
G4T1 '-
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�y
FLOW DIAGRAM
Y'
FORMER SEABOARD CKEMICAL FAC) ..# 1 # I
FORMER
�
k SALE DRIVE LANDFILL WE
co
ova
4F14TORE}1EA1f,7104
M
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IRRMTM
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0 Z
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(0 L (n
Z
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0 co
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Figure 3

FIGURE 4 — VOC Trend Graphs
35

FIGURE 5 — IA-Dioxane Trend Graphs
36