NCD981021157_19920903_New Hanover County Airport Burn Pit_FRBCERCLA FS_Final Feasibility Study Report-OCR

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t<ECifJVtU
SEP O !l 1992
SUPERfUNOSltTI0N
REMEDIAL PLANNING ACTIVITIES AT SELECTED
UNCONTROLLED HAZARDOUS SUBSTANCES DISPOSAL
SITES FOR EPA REGION IV
U.S. EPA CONTRACT NO. 68-W9-0056
FINAL
FEASIBILITY STUDY REPORT FOR THE
NEW HANOVER COUNTY AIRPORT
BURN PIT SITE
WILMINGTON, NORTH CAROLINA
WORK ASSIGNMENT NO. 005-4L5Q
DOCUMENT CONTROL NO.
7740-005-FS-BGSG
September 3, 1992
Prepared for:
U.S. Environmental Protection Agency
Prepared by:
CDM Federal Programs Corporation
2030 Powers Ferry Road
Suite 490
Atlanta, Georgia 30339
**COMPANY CONFIDENTIAL**
reon,....u...,..1..1...1
3 19
G[gj'·
IPA -REGION IV
J'..'l'LANTA,GA
This document has been prepared for the U.S. Environmental Protection Agency under Contract
No. 68-W9-0056. The material contained herein is not to be disclosed to, discussed with, or
made available to any person or persons for any reason without the prior expressed approval of
a responsible official of the U.S. Environmental Protection Agency.
CDM ARCS IV
Atlanta, Georgia
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TABLE OF CONTENTS
Section
EXECUTIVE SUMMARY .............................. ES-1
1.0 INTRODUCTION .................................. 1-1
1.1 Purpose ....................... _ .............. 1-1
1.2 Site Location and History . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1. 3 Environmental Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
1.3.1 Physical Features ........................... 1-5
1.3.2 Hydrology ............................... 1-8
1.3.3 Regional Hydrogeology ....................... 1-9
1.3.4 Site Hydrogeology ......................... 1-13
1.4 Results of Previous Investigations . . . . . . . . . . . . . . . . . . . . 1-21
1.4.1 Remedial Investigation . . . . . . . . . . . . . . . . . . . . . . . 1-21
1.4.2 Baseline Risk Assessment . . . . . . . . . . . . . . . . . . . . . 1-22
1.5 Site Restoration Objectives for Groundwater . . . . . . . . . . . . . . 1-27
1.5.1 Applicable or Relevant and Appropriate
Requirements (ARARs) . . . . . . . . . . . . . . . . . . . . . 1-27
1.5.2 Waivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-31
1.5.3 Media of Concern . . . . . . . . . . . . . . . . . . . . . . . . . 1-37
1.5.4 Remedial Action Objectives . . . . . . . . . . . . . . . . . . . . 1-37
1.5.5 Extent of Groundwater Contamination . . . . . . . . . . . . . 1-38
2.0 IDENTIFICATION, SCREENING, AND EVALUATION OF
TECHNOLOGIES AND PROCESS OPTIONS . . . . . . . . . . . . . 2-1
2.1 Screening of Groundwater Technologies and Process Options . . . . 2-1
2.2 Evaluation of Technologies and Process Options . . . . . . . . . . . . 2-4
2.2.1 Containment Technologies . . . . . . . . . . . . . . . . . . . . . 2-4
2.2.2 Extraction Technology . . . . . . . . . . . . . . . . . . . . . . . . 2-6
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Section
TABLE OF CONTENTS
( continued)
2.2.3 Treatment Technologies ....................... 2-7
2. 2.4 Discharge Technologies . . . . . . . . . . . . . . . . . . . . . . 2-20
2.3 Summary of Process Options Evaluation . . . . . . . . . . . . . . . . 2-23
2.4 Development of Remedial Action Alternatives . . . . . . . . . . . . . 2-23
3.0 EVALUATION OF REMEDIAL ACTION ALTERNATIVES ....... 3-1
3.1 Groundwater Extraction Analysis ...................... 3-2
3 .1.1 Aquifer Characteristics . . . . . . . . . . . . . . . . . . . . . . . . 3-3
3.1.2 Groundwater Modeling Assumptions ............... 3-3
3.1.3 Theis Analysis Results ........................ 3-4
3.2 Alternative 1 -No Action . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6
3.2.1 Descnption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6
3.2.2 Evaluation ............................... 3-7
3.3 Alternative 2 -Vertical Barrier ....................... 3-8
3.3.1 Description ............................... 3-8
3.3.2 Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-10
3.4 Alternative 3 -Groundwater Extraction and Physical Treatment
(Air Stripping) with Discharge to POTW . . . . . . . . . . . . . . 3-14
3.4.1 Descnption .............................. 3-14
3.4.2 Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-16
3.5 Alternative 4 -Groundwater Extraction and Physical/Chemical
Treatment (Chromium Reduction, Metals Precipitation, and
Air Stripping) with Discharge via Spray Irrigation . . . . . . . . . 3-20
3.5.1 Descnption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-20
3.5.2 Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-23
ii
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Section
4.0
TABLE OF CONTENTS
( continued)
3.6 Alternative 5 -Groundwater Extraction and Physical/Chemical
Treatment (Chromium Reduction and Metals Precipitation) with
Discharge to Surface Water . . . . . . . . . . . . . . . . . . . . . . 3-28
3. 6.1 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-28
3.6.2 Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-30
ANALYSIS AND SUMMARY OF ALTERNATIVES ........... 4-1
4.1 Threshold Criteria ............................... 4-3
4.1.1 Overall Protectiveness ........................ 4-3
4.1.2 Compliance with ARARs ...................... 4-3
4.2 Primary Balancing Criteria ......................... 4-5
4.2.1 Long-Term Effectiveness and Performance ........... 4-5
4.2.2 Reduction of M/T/V Through Treatment ............. 4-5
4.2.3 Short-Term Effectiveness . . . . . . . . . . . . . . . . . . . . . 4-11
4.2.4 Implementability . . . . . . . . . . . . . . . . . . . . . . . . . . 4-11
4.2.5 Cost Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-11
4.3 Summary ................................... 4-12
REFERENCES
APPENDICES
Appendix A -Boring and Well Logs
Appendix B -Groundwater Analytical Results
Appendix C -Cost Estimates
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LIST OF FIGURES
Figure
1-1 Site Location Map ................................. 1-2
1-2 Site Features Map • • • • • • ■ • • • • • • • • • • • • • • • • • • • • • • • • • • 1-6
1-3 Regional Hydrogeologic Cross-Section Location Map . . . . . . . . . . . 1-10
1-4 Regional Hydrogeologic Cross-Section A-A' . . . . . . . . . . . . . . . . 1-11
1-5 Site Hydrogeologic Cross-Section Location Map . . . . . . . . . . . . . . 1-15
1-6
1-7
Site Hydrogeologic Cross-Section B-B'
Water Level Elevations -April 9, 1991
1-16
1-17
1-8 Water Level Elevations -April 17, 1991 . . . . . . . . . . . . . . . . . . 1-18
1-9 Water Level Elevations -May 7, 1991 . . . . . . . . . . . . . . . . . . . . 1-19
1-10 Extent of Benzene Contamination in the Surficial Aquifer (µg/1) 1-39
1-11 Approximate.Extent of Chromium Contamination
in the Surficial Aquifer (µg/1) . . . . . . . . . . . . . . . . . . . . . . . . 1-40
1-12 Approximate Extent of Chloroform Contamination
in the Surficial Aquifer (µg/1) . . . . . . . . . . . . . . . . . . . . . . . . 1-41
1-13 Approximate Extent of Benzene Contamination
in the Surficial Aquifer (µg/1) . . . . . . . . . . . . . . . . . . . . . . . . 1-42
1-14 Approximate Extent of Contamination in the Surficial Aquifer . . . . . 1-43
2-1 Typical Air Stripping Tower . . . . . . . . . . . . . . . . . . . . . . . . . . 2-11
2-2 . Typical Activated Carbon Filter . . . . . . . . . . . . . . . . . . . . . . . . 2-16
3-1 Extraction Well Drawdown at Steady State (15 gpm) . . . . . . . . . . . . 3-5
3-2 Cross-Section of Typical Impermeable Surface Cap . . . . . . . . . . . . . 3-9
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LIST OF TABLES
Table
ES-1 Summary of Alternatives Evaluation . . . . . . . . . . . . . . . . . . . . . ES-7
1-1 Well Construction and Water Level Data . . . . . . . . . . . . . . . . . . 1-20
1-2 Groundwater Data Summary . . . . . . . . . . . . . . . . . . . . . . . . . . 1-23
1-3 Groundwater Quality Standard Based Risks . . . . . . . . . . . . . . . . . 1-28
1-4 Potential Chemical-Specific ARARs . . . . . . . . . . . . . . . . . . . . . 1-32
1-5
1-6
2-1
2-2
2-3
2-4
2-5
2-6
4-1
4-2
4-3
4-4
4-5
Potential Action-Specific ARARs for Groundwater . . . . . . . . . . . . 1-34
Potential Location-Specific ARARs . . . . . . . . . . . . . . . . . . . . . . 1-36
Initial Screening of Technologies and Process Options . . . . . . . . . . . 2-2
Optimum Treatment pH Values . . . . . . . . . . . . . . . . . . . . . . . . . 2-9
Henry's Law Constants for Volatile Compounds of Concern
Freundlich Parameter K Values for Contaminant Compounds
2-13
2-17
Effluent Criteria for Discharge Alternatives . . . . . . . . . . . . . . . . . 2-21
Evaluation of Process Options . . . . . . . . . . . . . . . . . . . . . . . . . 2-24
Summary of Institutional and Land Use Restrictions . . . . . . . . . . . . 4-2
Summary of the Public Health and Environmental Effects Evaluation 4-4
Federal Regulations Affecting Implementation of the Alternatives
Under Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6
North Carolina Regulations Affecting the Implementation of the
Alternatives Under Evaluation . . . . . . . . . . . . . . . . . . . . . . . . 4-7
Local Regulations Affecting the Implementation of the
Alternatives Under Evaluation . . . . . . . . . . . . . . . . . . . . . . . . 4-8
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LIST OF TABLES
( continued)
4-6 Long-Term Effectiveness and Permanence Evaluation for
Remedial Action Alternatives . . . . . . . . . . . . . . . . . . . . . . . . . 4-9
4-7 Short-Term Effectiveness and Implementability Evaluation . . . . . . . . 4-10
4-8 Summary of Present Worth Costs for Remedial Action Alternatives . . 4-13
4-9 Summary of Alternatives Evaluation . . . . . . . . . . . . . . . . . . . . . 4-14
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EXECUTIVE SUMMARY
The New Hanover County Airport Burn Pit Site located in Wilmington, North
Carolina, was proposed for inclusion on the National Priorities List (NPL) on June
24, 1988, and was placed on the NPL in March 1989. Soil removal activities were
performed at the site in 1990, following a signed Administrative Order of Consent
from EPA. A remedial investigation (RI) was then conducted by EPA in 1991 (EPA,
1991). The purpose of this feasibility study (FS) is to determine the extent of
groundwater contamination and to evaluate the possible remedial action alternatives
for the site.
SITE DESCRIPTION AND HISTORY
The New Hanover County Airport Burn Pit Site is located on Gardner Drive,
approximately 300 feet west of the New Hanover County Airport, and about 1.5 miles
north of Wilmington, North Carolina. The site is approximately four acres in size
with the former burn pit area occupying about 1,500 square feet near the center of the
site.
Land use in the vicinity of the site is commercial, industrial, and residential. The
Airport Authority intends to maintain the entire west side of the airport for industrial
development and is actively marketing the available industrial property. Currently,
there are several occupants near the site, including a rental car maintenance facility, a
closed sawmill/lumberyard, and a trucking company. The closest residential area is
separated from the site by a road, railroad tracks, and a wooded area, and is
estimated to be approximately 0.2 miles to the west. Southwest of the site are ten
underground storage tanks (USTs). Approximately 600 feet from the site is a forested
area.
ES-1
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An airport facility was originally built at the site in the 1920s .. The airport was used
as a military hospital during World War II. The date of construction of the original
pit is unknown, but a second pit was constructed in 1968 and used until 1979 by the
Air Force Cape Fear Technical Institute and local industries for firefighter training
purposes. The Wilmington Fire Department also used the bum pit for firefighter
training purposes during the years 1968 to 1974. It has been estimated that 100 to
500 gallons of jet fuel were burned in the pit for each practice activity during this
period. Jet fuel, gasoline, petroleum storage tank bottoms, fuel oil, kerosene, sorbent
materials from oil spill cleanups, and on at least one occasion, confiscated marijuana,
were burned in the pit. Although water was the primary extinguishing agent, carbon
dioxide and dry chemicals were also used.
The county applied for a permit to close the bum pit by land application of the pit
contents, but this request was denied by the state. Sampling by the New Hanover
County Department of Engineering in 1985 showed heavy metals and volatile organic
compounds (VOCs) in the pit sludge. In May 1986, the North Carolina Department
of Health Services sampled the bottom sludge layer of the pit and soil adjacent to the
outside of the pit. Heavy metals, polycyclic aromatic hydrocarbons (PAHs), and
VOCs were detected in these samples. A survey for hazard ranking purposes was
conducted at the site on January 9, 1987 by EPA. The site was proposed for
inclusion on the National Priorities List (NPL) on June 24, 1988.
The New Hanover County Airport Bum Pit Site was placed on the NPL in March of
1989. EPA identified the potentially responsible parties (PRPs) as New Hanover
County (owner of the.airport), the City of Wilmington, Cape Fear Technical Institute,
the United States Air Force (all of which trained frrefighters at the site), and the
United States Customs Service (burned confiscated drugs at the site).
The Agency for Toxic Substances and Disease Registry (ATSDR) conducted a health
assessment of the New Hanover County Airport Bum Pit Site in March of 1989. The
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health assessment concluded that the site is of potential public concern because of risk
to human health resulting from possible exposure to hazardous substances at
concentrations that may result in adverse human health effects. On March 19, 1990,
New Hanover County repaired a break in the berm around the bum pit area. In April
of 1990, EPA collected soil and groundwater samples at the site as part of an
emergency response to the break in the berm.
EPA gave approval to the PRPs to perform removal activities at the site following a
signed Administrative Order of Consent effective May 11, 1990. Consequently, in
November and December of 1990, the PRPs removed waste materials from the bum
pit and firefighting area along with contaminated surface and subsurface soils.
Structures associated with firefighter training activities were dismantled and removed.
All removal activities were overseen by EPA. The structures consisted of a fuel
supply tank and associated underground piping, a railroad tank car, automobile
bodies, and an aircraft mockup. Soil removal continued in these areas until no visual
contamination remained or groundwater was encountered. EPA obtained soil samples
from the bottom of the excavated areas prior to backfilling to grade with clean soil.
The sampling investigation was performed following soil removal to confirm the
complete excavation of contaminated soil. Several drums of paint sludge were also
found at the perimeter of the site and were removed and properly disposed of
according to Resource Conservation and Recovery Act (RCRA) regulations.
PREVIOUS INVESTIGATIONS
A remedial investigation was performed by EPA in 1991. Preliminary remediation
goals (PRGs) were developed for the site by EPA for groundwater and soil. The soil
PRGs were intended to be protective of exposure via both air and soil ingestion
pathways. These criteria were used to determine if contaminated soils had been
completely excavated and removed.
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Based on the results of previous soil and groundwater confirmation sampling, it was
determined that all soils above the PRGs had been removed and that the extent of
contaminated groundwater required further delineation. Three rounds of groundwater
samples were collected from the permanent wells. The first round of samples was
collected on April 17, 1991, and analyzed for volatile organic compounds (VOCs),
semi-volatile organic compounds (SVOCs), and metals in groundwater only. The
second round of groundwater samples were collected on May 7, 1991, and analyzed
for VOCs in groundwater only. The third round was collected in November, 1991
and analyzed for voes, SVOCs, and metals.
In April 1992, FPC conducted a human health and ecological assessment to evaluate
the potential risks from exposure to chemicals present at the New Hanover County
Airport Bum Pit Site. The risk assessment concluded that soil, surface water, and
fugitive dust are not expected to be significant pathways of exposure at the site in its
existing condition. However, based on the future potential exposure to local residents
via consumption of contaminated drinking water and inhalation of contaminant vapors
by showering, six groundwater chemicals of concern at the site were identified. The
chemicals of concern in groundwater at the site are benzene, chloroform, chromium,
1,2-dichloroethane, ethylbenzene, and lead, based on toxicity, frequency of detection,
and exceedance of water quality standarcis: Finally, the risk assessment did not
identify the presence of endangered species of flora or fauna.
EXTENT OF CONTAMINATION
The chemicals of conc~m in groundwater at the site are benzene, chloroform,
chromium, 1,2-dichloroethane, ethylbenzene, and lead. The derived cleanup goals for
benzene, chloroform, chromium, 1,2-dichloroethane, ethylbenzene, and lead were
based on the North Carolina Drinking Water Quality Standards. The cleanup goal for
lead was based on new regulations for treatment technique action levels.
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The extent of groundwater contamination was estimated by using a compilation of
three separate plumes --benzene at 5 µg/1, chromium at 50 µgll, and chloroform at
0.19 µgll. Because lead was detected in one well and during one sampling round
only, and 1,2-dichloroethane was detected only in one well during two sampling
rounds, and since these two wells are within the total extent of groundwater
contamination, specific plumes were not estimated for these compounds. The
approximate total areal extent of groundwater contamination is 3.4 acres. The
vertical extent of contamination extends throughout the 28 feet of the surficial aquifer.
However, to better define the extent of contamination, several additional monitor
wells should be installed.
REMEDIAL ACTION ALTERNATIVES
Remedial action alternatives were formulated considering groundwater contaminant
types, contaminant concentrations, and applicable technologies. The five alternatives
assessed for this site are:
Alternative 1 -No Action
Alternative 2 -Vertical Barrier
Alternative 3 -Groundwater Extraction and Physical Treatment (Air Stripping) with
Discharge to POTW
Alternative 4 -Groundwater Extraction and Physical/Chemical Treatment
(Chromium Reduction, Metals Precipitation, and Air Stripping) with
Discharge via Spray Irrigation
Alternative 5 -Groundwater Extraction and Physical/Chemical Treatment
(Chromium Reduction and Metals Precipitation) with Discharge to
Surface Water
The alternatives were evaluated on the basis of long-term effectiveness, compliance
with applicable or relevant and appropriate requirements (ARARs), reduction of
toxicity, mobility, or volume through treatment, short-term effectiveness,
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implementability, and cost. A summary of this evaluation is presented in
Table ~-1.
ES-6
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- - - - ---
I: No Action Ongoing monitoring of
groundwater contaminant
levels would be conducted
to assess contaminant mi-
gration. Does not meet
ARARs.
2: V crtical Barrier The potential for offsite
contamination migration is
greatly reduced. ARARs
are not met at the site.
Length of service un-
known (not permanent).
-- ----- -
TABLE ES-1
SUMMARY OF ALTERNATIVES EVALUATION
NEW HANOVER COUNTY AIRPORT BURN PIT SITE
WILMINGTON; NORTH CAROLINA
None. None. None.
Greatly reduces Potential release of Design of slurry wall and im-
mobility. No reduction organic volatiles dur-permeable cap; stonnwater
in toxicity and volume. ing slurry wall instal-runoff drainage and collection
lation. Noise nuisance for cap. Air monitoring during
due to operation of implementation.
heavy equipment.
- ---
0 74.7
1.5 1,087.7
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- - - -
3: Groundwater
Extraction and
Physical Treatment
(Air Stripping)
With Discharge to
POTW
--
Permanent remedy.
ARARs are met.
- - -
Eliminates MrfN of
contaminants. Elimi-
nates potential for
offsite migration. High
degree of risk reduction
for ingestion and inha-
lation of groundwater.
--
TABLE ES-!
( continued)
Potential release of
organic volatiles dur-
ing extraction and
treatment system
operation. Noise
nuisance due to
operation of drilling
equipment.
----
Design of extraction, treatment,
and discharge systems. Air
stripping of benzene to "below
detection limit" required.
Treatment of air stripping off-
gases may be required. Pre-
treatment for TSS and iron may
be required. Discharge permit
acquisition under consideration.
Ongoing monitoring of ground-
water contaminant levels and the
treatment system should be con-
ducted to assess extraction and
treatment systems performance.
Must meet City of Wtlmington
P01W discharge requirements
and CAA requirements. No
future land use restrictions
would be required.
-
4.5
-- -
1,889.9
NHANFS09.038
---- --
4: Groundwater Permanent remedy.
Extraction and Physi-ARARs are met.
cal/Chemical Treat-
ment (Chromium
Reduction, Metals
Precipitation, and
Air Stripping) with
Discharge via Spray
Irrigation
---
Eliminates MrrN of
contaminants.
Eliminates potential for
offsite migration.
Greatest deg= of risk
reduction for ingestion
and inhalation of
groundwater.
----- -
TABLE ES-I
(continued)
Potential release of
organic volatiles dur-
ing extraction well
installation. Noise
nuisance due to opera-
tion of drilling
equipment.
Sludge/filter cake
generation from pre-
cipitate.
Design of extraction, treatment,
and discharge systems. Metals
precipitation should achieve
required North
Carolina Drinking Water Quali-
ty Standards for inorganics. Air
stripping should achieve stan-
dards for organics. Treatment
of air stripping off-gases may be
required. Pretreatment for TSS
and iron may be required.
Storage may be required during
wet weather and under freezing
temperature conditions. Ongo-
ing monitoring of groundwater
contaminant levels and the
treatment system should be con-
ducted to assess extraction and
treatment systems perfonnance.
Must meet North Carolina
Drinking Water Quality Stan-
dards for groundwater and CAA
emissions requirements.
-- --
4.5 2,319.2
NHA...-F5'09.038
----
5: Groundwater
Extraction and Phys-
ical/Chemical
Treatment (Chromi-
um Reduction and
Metals Precipitation)
with Discharge to
Surface Water
--
Permanent remedy.
ARARs are met.
- --
Eliminates MffN of
contaminants. Reduce
source of groundwater
contamination. Great-
est degree of risk re-
duction for ingestion
and inhalation of
groundwater.
------
TABLE ES-I
(continued)
Potential release of
organic volatiles dur-
ing extraction well
installation. Noise
nuisance, due to oper-
ation of drilling
equipment.
Sludge/filter cake
generation from pre-
cipitate.
Design of extraction, treatment,
and discharge systems. Metals
precipitation should achieve
North Carolina Surface Water
discharge requirements for
inorganics. A 4,000-foot
pipeline would be required for
discharge to Smith Creek.
Permit acquisition under
consideration. Ongoing
monitoring of groundwater
contaminant levels and the
treatment system should be
conducted to assess extraction
and treatment systems
performance. Must meet North
Carolina Surface Water dis-
charge requirements.
----
5 2,326.9
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1.0 INTRODUCTION
1.1 PURPOSE
CDM Federal Programs Corporation (FPC) has prepared this Feasibility Study (FS)
Report for the New Hanover County Airport Burn Pit Site (the site) in Wilmington,
North Carolina, under contract to the U.S. Environmental Protection Agency (EPA).
The purpose of this report is to present viable alternatives for remediation of the New
Hanover County Airport Burn Pit Site. These alternatives are designed to be
consistent with objectives of the Superfund Amendments and Reauthorization Act of
1986 (SARA), the National Contingency Plan (EPA, 1992a) and current EPA
Guidance for Conducting Remedial Investigations and Feasibility Studies Under the
Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA)
(EPA, 1988).
1.2 SITE LOCATION AND HISTORY
SITE LoCATION
The New Hanover County Airport Burn Pit Site is located on Gardner Drive,
approximately 300 feet west of the New Hanover County Airport, 1.5 miles north of
Wilmington, North Carolina at 34 ° 16'29" north latitude and 77°54'55" west
longitude. The site is approximately 4 acres in size with the former burn pit area
occupying about 1,500 square feet near the center of the site. The site location is
shown on Figure 1-1.
Land use in the vicinity of the site is commercial, industrial, and residential. The
Airport Authority intends to maintain the entire west side of the airport for industrial
development and is actively marketing the available industrial property. Currently,
there are several occupants near the site, including a rental car maintenance facility, a
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-CDMFEDERALPROGllAMSCORPORATION
•~olCaq,~A)k.&Nlm=.
SITE LOCATION MAP
NEW HANOVER COUNTY AIRPORT BURNPIT SITE
' WILMINGTON, NORTH CAROLINA
FIGURE No. 1-1
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closed sawmiWlumberyard, and a trucking company. The closest residential area is
separated from the site by a road, railroad tracks, and a wooded area, and is
estimated to be approximately 0.2 miles to the west. Southwest of the site are ten
underground storage tanks (USTs). Approximately 600 feet from the site is a forested
area.
The average annual precipitation of 53.35 inches is fairly evenly distributed
throughout the year. Historically, July is the wettest month. October through
December are generally drier than the spring and summer months. Over an annual
period, average monthly temperatures range from 45.6 degrees Fahrenheit (F) in
January to 80.3 degrees Fin July. The warm summer temperatures, combined with
heavy precipitation in these months, maintain a humid environment.
SITE HISTORY
The airport was built in the 1920s as a civil air facility owned by New Hanover
County. In 1942, the Department of Defense requisitioned the airport for the U.S.
Army Air Corps. In 1947 and 1948, the Army deeded the airport back to the county.
Formerly known as Bluthenthal Airport, in 1970 the facility was renamed as the New
Hanover County Airport.
The airport was originally developed as a military hospital during World War II. The
date of construction of the original burn pit is unknown, but a second pit was
constructed in 1968 and used until 1979 by the Air Force, Cape Fear Technical
Institute, and local industries for firefighter training purposes. The Wilmington Fire
Department also used the burn pit for firefighter training purposes during the years
1968 to 1974. It has been estimated that 100 to 500 gallons of jet fuel were burned in
the pit for each practice activity during this period. Jet fuel, gasoline, petroleum
storage tank bottoms, fuel oil, kerosene, sorbent materials from oil spill cleanups, and
on at least one occasion, confiscated marijuana, were burned in the pit. Water was
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the primary fire extinguishing agent; however, carbon dioxide and dry chemicals were
also used.
The county applied for a permit to close the bum pit by land application of the pit
contents, but this request was denied by the state. Sampling by the New Hanover
County Department of Engineering in 1985 showed heavy metals and volatile organic
compounds (VOCs) in the pit sludge. In May 1986, the North Carolina Department
of Health Services sampled the bottom sludge layer of the pit and soil adjacent to the
outside of the pit. Heavy metals, polycyclic aromatic hydrocarbons (PAHs), and
VOCs were detected in these samples. A survey for hazard ranking purposes was
conducted at the site on January 9, 1987 by EPA. The site was proposed for
inclusion on the National Priorities List (NPL) on June 24, 1988.
The New Hanover County Airport Bum Pit Site was placed on the NPL in March of
1989. EPA identified the potentially responsible parties (PRPs) as New Hanover
County (owner of the airport), the City of Wilmington, Cape Fear Technical Institute,
the United States Air Force (all of which trained firefighters at the site), and the
United States Customs Service (burned confiscated drugs at the site).
The Agency for Toxic Substances and Disease Registry (ATSDR) conducted a health
assessment of the New Hanover County Airport Bum Pit Site in March of 1989. The
health assessment concluded that the site is of potential public concern because of risk
to human health resulting from possible exposure to hazardous substances at
concentrations that may result in adverse human health effects.
On March 19, 1990, New Hanover County repaired a break in the berm around the
bum pit area. In April of 1990, EPA collected soil and groundwater samples at the
site as part of an emergency response to the break in the berm.
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EPA gave approval to the PRPs to perform removal activities at the site following a
signed Administrative Order of Consent effective May 11, 1990. Consequently, in
November and December of 1990, the PRPs removed waste materials from the bum
pit and firefighting areas along with contaminated surface and subsurface soils.
Structures associated with firefighter training activities (shown in Figure 1-2) were
dismantled and removed. All removal activities were overseen by EPA. The
structures consisted of a fuel supply tank and associated underground piping, a
railroad tank car, automobile bodies, and an aircraft mockup. Soil removal continued
in these areas until no visual contamination remained or groundwater was
encountered. EPA obtained soil samples from the bottom of the excavated areas prior
to backfilling to grade with clean soil. The sampling investigation was performed
following soil removal to confirm the complete excavation of contaminated soil.
Several drums of paint sludge were also found at the perimeter of the site and were
removed and properly disposed of according to Resource Conservation and Recovery
Act (RCRA) regulations. Groundwater samples were collected from four temporary
monitor wells during the removal action. A discussion of more recent site
investigations and the results of all the groundwater sampling rounds are discussed in
Section 1.4.
1.3 ENVIRONMENTAL SETTING
1.3.1 PHYSICAL FEATURES
The New Hanover County Airport Bum Pit Airport, as well as the subject site, are
situated on a local topographic high point in the area. The site occupies
approximately 4 acres of land on the western side of the airport and is surrounded by
asphalt paved roadways. Topography at and in the vicinity of the site is relatively flat
with elevations ranging from approximately 28 to 32 feet above mean sea level
(ams!). The roadways surrounding the site are slightly elevated, creating a basin
within the site. The site is mainly open and grass-covered. Some interspersed,
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APPROXIMATE
SCALE IN FEET
-
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LEGEND
1!111111
BERM/ROAD
EXCAVATION
POSSIBLE SURFACE WATER
OR.AJNAGE AREAS
ARMY CORPS
OF ENGINEERS
UST FARM
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CDM FEDERAL PROGRAMS CORPORATION
a ,ublidivy o(Camp Dn::Hcr & McKee Enc..
- - ------ - -
TO WILMINGTON
SITE FEATURES MAP
NEW HANOVER COUNTY AIRPORT BURN PIT SITE
WILMINGTON, NORTH CAROLINA
BUILDING
FOUNDATIONS
-
SUPPLY TANK
{Removed)
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FIGURE No. 1·2
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semi-mature to mature pine trees exist along the roadways and in the southeastern
corner of the site. The area surrounding the site is mainly wooded.
Existing man-made structures at the site include the remnants of a military hospital
once present at the site. The remnants consist of three concrete block buildings, two
building foundations, and a septic tank. The three concrete block buildings include
two smaller buildings in the center of the site and a larger structure in the
southeastern corner of the site. All three buildings are abandoned and in disrepair.
The two building foundations are located in the southeastern corner of the site and are
the remnants of the largest buildings constructed on the site. The septic tank utilized
by the hospital is buried and located along the southern site boundary. These site
features are shown in Figure 1-2.
All site features associated with the burn pit and the fire fighter training activities
were removed in November and December of 1990 (previously discussed in
Section 1.2). These features included the burn pit, two oil-stained areas north of the
burn pit, an above-ground 10,000-gallon supply tank, underground piping from the
supply tank to the simulation areas, a valve box, an old automobile in the auto burn
area, two tank trucks and a railroad tank car in the tank car burn area, and a mock
aircraft made from 55-gallon drums in the aircraft burn area. The exact locations
from which the old automobile and the mock aircraft were removed are unknown.
The former burn pit was a 3-foot high, 30-by 50-foot rectangular berm constructed at
land surface. All contaminated soils associated with the burn pit and the two oil-
stained areas north of the burn pit have been excavated and removed from the site.
The excavations have been backfilled and graded to land surface with clean soils.
The areas are now covered with grass.
Regional physical features in the vicinity of the site include the Cape Fear River, the
Northeast Cape Fear River and their associated tidal flats to the west of the site, Ness
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Creek to the northwest of the site and Smith creek to the south of the site (see
Figure 1-1). Land surface elevations increase northeast of the site.
1.3.2 HYDROLOGY
The hydrology, or surface water drainage, at the bum pit site is markedly influenced
by the surficial sands. The surficial sands are permeable, allowing most precipitation
to infiltrate into the sands and recharge the surficial aquifer or become
evapotranspirated through the grasses growing at the site. The surficial sands are
permeable enough such that overland flow does not occur during most precipitation
events. In the rare event when the precipitation rate exceeds the infiltration capacity
of the sands, overland flow is retained onsite due to the slightly elevated roadways
encircling the site. Drainage ditches exist on the site along the southern, western, and
southeastern site boundaries; however, the ditches terminate with no established
discharge points offsite. Three low-lying areas exist along the boundaries of the site
(shown in Figure 1-2) where at times standing water is present; however, it appears
that little or no offsite drainage occurs. Perimeter ditches also exist along the
roadways outside the site on the west, north, and east site boundaries.
Regionally, the bum pit site is located on the western side of a north-south trending
topographic divide. Surface water drainage features splay south and west from the
site vicinity towards the Northeast Cape Fear River and its tidal flats approximately a
mile to the west and Smith Creek, approximately 4,800 feet to the south. Smith
Creek flows west into the Northeast Cape Fear River, which flows south into the
Cape Fear River which continues south into the Atlantic Ocean. Regional surface
water features are shown in Figure 1-1.
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1.3.3 REGIONAL HYDROGEOLOGY
New Hanover County is located in the Coastal Plain Physiographic Province of North
Carolina. The regional geology and hydrogeology of the county are marked by 1,100
to 1,500 feet of unconsolidated and consolidated sediments overlying a crystalline
basement of metamorphic and igneous rock (Bain, 1970). Three aquifers are of
importance as drinking water sources in New Hanover County: (in descending order
below land surface) the surficial aquifer of undifferentiated late tertiary and surficial
deposits, the Castle Hayne limestone of the Castle Hayne Limestone Formation, and
the sandstone aquifer of the Pee Dee Formation. A regional cross-section location
map (Figure 1-3) and a regional cross-section (Figure 1-4) shows the relationships of
these aquifers to one another.
The surficial aquifer, the uppermost in the area, is composed of undifferentiated late
tertiary sediments and surficial deposits and consists mainly of coarse to fine quartz
sands and, to a lesser extent, clays silts and marls. The hydrogeologic unit ranges
from 20 to 60 feet in thickness (Bain, 1970). In the areas of Castle Hayne in the
northern part of the county and in Wilmington south of the site, the surficial aquifer is
absent. The sediments of the surficial aquifer lie unconformably on an erosional
surface. of the slightly dipping sediments of the Castle Hayne Limestone Formation
and the Pee Dee Formation (EPA, 1992b). The water in the surficial aquifer exists
under water table conditions and conforms to the topography in a·subdued manner.
The water table is generally encountered less than 10 feet below land surface.
Regional groundwater flow direction in the surficial aquifer is southeast towards the
Atlantic Ocean; however, local groundwater flow directions are dictated by
topography and recharge/discharge features, such as surface water bodies.
Recharge to the surficial aquifer is through infiltration of precipitation. Studies
indicate that, in some areas of the county, up to 90 percent of precipitation infiltrates
the surficial aquifer (Bain, 1970). Water is discharged from the surficial aquifer to
1-9
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A
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REGIONAL HYDROGEOLOGIC CROSS-SECTION LOCATION MAP
-NEW HANOVER COUNTY AIRPORT BURN PIT SITE
CDM FEDERAL PROGRAMS CORPORATION WILMINGTON, NORTH CAROLINA • sv.t.idicy of Camp ~.t. Mc.Xoe 1Dc. FIGURE No. 1-3
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CDM FEDERAL PROGRAMS CORPORATION
REGIONAL HYDROGEOLOGIC CROSS-SECTION A-A'
NEW HANOVER COUNTY AIRPORT SITE
WILMINGTON, NORTH CAROLINA • Hboidi&r)' orcauv Drc,oer A Mete= tnc. FIGURE No. 1-4
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surface water features and through infiltration to lower aquifers. Regionally, aquifer
parameters measured in the surficial aquifer indicate a range of hydraulic conductivity
values from 14 ft/day to 697 ft/day, transmissivity values from 378 ff/day to greater
than 17,425 ft2/day, storage coefficient (specific yield) values from 0.15 to 0.5
(dimensionless), and specific capacity of well values from 0.1 to 69 gpm/ft of
drawdown (Bain, 1970).
The Castle Hayne limestone lies below the surficial aquifer. The limestone ranges
from 0 to 80 feet in thickness, but is generally less than 50 feet thick and in the
northwestern portions of New Hanover County, the limestone is thin to absent. The
formation is variable lithologically and is typically composed of four units. In
descending order, the units consist of an upper light-green glauconitic mixture of shell
fragments containing bryowans, a "cap rock" of chalk-white siliceous limestone
containing phosphate at its base, a glauconitic shell limestone with interbedded sand,
and a basal sandy shell conglomerate. The entire formation lies unconformably on
the erosional surface of the upper clay aquiclude of the Pee Dee Formation. The
water in the Castle Hayne limestone occurs under water table conditions in the
northern sections of the county but may be confined beneath clay beds in other
sections of the county (Bain, 1970).
The groundwater flow direction in the limestone is southeast toward the Atlantic
Ocean in the eastern portion of the county and west toward the Northeast Cape Fear
River and the Cape Fear River in the western portion of the county. Recharge to the
limestone is through infiltration of water from the overlying surficial aquifer and
through direct infiltration of precipitation in the Wilmington and Castle Hayne areas
where the limestone outcrops at land surface or the surficial aquifer is thin. Aquifer
parameters measured for the limestone indicated a range of hydraulic conductivity
values from 18.7 ft/day to 375 ft/day, transmissivity values from 935 ff/day to
18,750 ft2, storage coefficient values from 0.0001 to 0.25 (dimensionless), and
specific capacity of well values from 3 to 60 gpm/ft of drawdown (Bain, 1970).
1-12
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The sandstone aquifer of the Pee Dee Formation is a major source for drinking water
in New Hanover County. It is separated from the Castle Hayne limestone by the
upper clay aquiclude of the Pee Dee Formation. This aquiclude ranges in thickness
from O to 50 feet. The undifferentiated late tertiary and surficial deposits lie
unconformably on the sandstone aquifer in the northwest areas of the county due to
the slight dip of the sandstone aquifer towards the Atlantic Ocean and an erosional
surface at the top of the aquifer. The aquifer is 35 feet in thickness throughout much
of the county and is composed mainly of quartz sands bound with a calcareous
cement. The aquifer is underlain by 150 feet of silt and clay. This silt and clay
forms an aquiclude that separates the sandstone aquifer from saline aquifers below.
Water in the sandstone aquifer occurs under artesian conditions due to the aquicludes
above and below. Recharge to the aquifer occurs through leakage from the upper
aquiclude and from the undifferentiated late tertiary and surficial deposits where they
overlay the aquifer.
Groundwater flow direction in the sandstone aquifer is toward the Atlantic Ocean in
the eastern part of the county and toward the Northeast Cape Fear River and the Cape
Fear River in the western part of the county. Discharge from the aquifer occurs
along the major stream valleys and through upward migration of water through the
upper beds along the Atlantic Coast (Bain, 1970). Aquifer parameters measured in
the sandstone aquifer indicate a range of hydraulic conductivities values from
28 ft/day to 268 ft/day, transmissivities values from 600 ff/day to 10,720 ft2/day,
storage coefficient values from 0.001 to 0.5 (dimensionless), and specific capacity of
wells from 0.3 to 34 gpm/ft of drawdown (Bain, 1970).
1.3.4 SITE HYDROGEOLOGY
The site-specific geology and hydrogeology of the New Hanover County Airport Bum
Pit Site has been investigated to a depth of 65 feet below land surface (bis) through
test borings and the installation of monitor wells. The investigations thus far have
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indicated three hydrogeologic units of concern beneath the site. These units include a
surficial silty sand aquifer, a thin clay unit beneath the surficial aquifer, and a lower
sand and limestone aquifer. A site hydrogeologic cross-section B-B' located on
Figure 1-5 and shown in Figure 1-6 indicates the hydrogeologic units encountered
beneath the site during investigative activities. Geologic logs of the test borings and
monitor wells shown in the cross-section are given in Appendix A.
· The surficial aquifer at the site, composed predominantly of silt has a thickness
between 25 and 31 feet throughout the site. Recharge to the aquifer occurs through
the direct infiltration of precipitation. All temporary piezometers, observation wells,
and monitor wells at the site have been installed in the surficial aquifer. Water level
contour maps generated from water level data collected from the wells consistently
indicate a groundwater mounding effect in the center of the site. Water level contour
maps generated from April 9, 1991, April 17, 1991 and May 7, 1991 water level data
are shown in Figures 1-7, 1-8, and 1-9, respectively. Water level data and well
construction details are shown in Table 1-1. The contours in Figures 1-7, 1-8, and
1-9 indicate an average hydraulic gradient across the site of 0.0015 ft/ft and a
groundwater flow direction radially out from the center of the site. Average aquifer
characteristics determined through an aquifer performance test performed in the
aquifer on May 8, 1991 indicate that the aquifer has an average transmissivity (T) of
146 ft2/day, an average storage coefficient (S) of 0.0063 (dimensionless), and an
average hydraulic conductivity (K) of 6.6 ft/day.
The unit beneath the surficial aquifer is a firm blue-gray clay. The clay unit was
consistently encountered in all three test borings (TB-1, TB-2, and TB-3) and deep
monitor well MWD-001 at a depth of 25 to 31 feet bis. The thickness of the unit,
determined from test boring TB-1, the only boring to penetrate the entire thickness of
the unit, is 6 feet. Permeability testing and geotechnical testing of a sample of the
clay obtained from the well boring of MWD-001 classify the clay as a sandy clay
with liquid limits of 34, a plastic index of 12, and a permeability of 2.03 x 10-1
1-14
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LEGEi,D
----BERM/ROAD ----
f'ITl''''''''"'"'lr" EXCAVATION
111111 POSSIBLE SURF AC( WAfER
DRAINAGE AREAS ... rrnPORARY PIEZOMETER
8 OBSERVATION WELL
• SHALLOW MONITOR WELL
® DEEP MONITOR WELL
0 fEST BORING
ARMY CORPS
OF ENGINEERS
UST FARM
WL-2
TO WILMINGTON
-
~ -----------------________ s __ lTE HYDROGEOLOGIC CROSS-SECTION LOCATION MAP
----NEW HANOVER COUNTY AIRPORT BURN PIT SITE CDM FEDERAL PROGRAMS CORPORATION
a 111t.idwy of Camp lm:11,cr .t. Md(ce Im:. WILMINGTON, NORTH CAROLINA
! f -N-
~ 100 0 100 200
APPROXIMATE
SCALE IN FEEf
FIGURE No. 1-5
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SOUTHWEST
"' ' g,
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40 "' cil "' ' " " ~ C ::;: 0 0 0 0 "'"' " "'
30
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-10
-20
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LEGEND
I /0'.i:I SlllY SAND
D CLAY
'-' "';; ~~ L>"' "'"' c, C
' ' ~~ ~~ " ,.
h£\t~'.2£l
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MEDIUM TO COARSE SAND
SANDY FOSSILIFEROUS
LIMESTONE
8
NORTHEAST
40
30
20
10 ai • !=,
El BLUE-GRAY CLAY POTENIIOMETRIC SURFACE
IN THE SURFICIAL AQUIFER
(May 7, 1991) 50 0 50 1:;iif.E@ FINE SAND HORIZONTAL
SCALE IN FEET
SITE HVDROGEOLOGIC CROSS-SECTION 8-8'
-NEW HANOVER COUNTY AIRPORT BURN PIT SITE =-=-"--------------CDM FEDERAL PROGRAMS CORPORATION WILMINGTON, NORTH CAROLINA 1.aut.idiaryofCampDrcuer & McKee hie. FIGURE No. 1-6
LEGEND
r<n""''"'"""r
1111111
BERM/ROAD
EXCAVATION
POSSIBLE SURFACE WATER
ORANAGE AREAS
TEMPORARY PIEZOMETER
OFFSITE MONITOR WELL
, ... 27,3 ......
WATER LEVEL CONTOUR (ft. AMSL)
EXTRAPOLAfED WATER LEVEL
CONTOUR (ft. AMSL)
0 SFC-001 (Approximate location)
-
ARMY CORPS
OF ENGINEERS
UST FARM
CDM FEDERAL PROGRAMS CORPORATION
• ntaidw)' of Camp Drc$Xr~ McKee Inc.
TO WILMINGTON
WATER LEVEL ELEVATIONS -April 9, 1991
NEW HANOVER COUNTY AIRPORt BURN PIT SITE
WILMINGTON, NORTli CAROLINA
100 0 100
APPROXIMATE
SCALE IN FEET
200
FIGURE No. 1-7
----BERM/ROAD ----
TJTT''""''"""" EXCAVATION
11111111 POSSIBLE SURFACE WATER
DRAJNAGE AREAS
• SHALLOW MONITOR WELL
® DEEP MONITOR WELL
0 OFFSITE MONITOR WELL
,-27.J-' WATER LEVEL CONTOUR (ft. AMSL)
.,-27.3--' EXTRAPOLATED WATER LEVEL
CONTOUR (ft. AMSL)
0 SFC-001 (Approximate location)
tU
ARMY CORPS
OF ENGINEERS
UST FARM
f
'
COM FEDERAL PROGRAMS CORPORATION
a 1u.baidi.vy o!Camp Drc11cr & McK.cc: Inc.
fO WILMINGTON
WATER LEVEL ELEVATIONS -April 17, 1991
NEW HANOVER COUNTY AIRPORT BURN PIT SITE
WILMINGTON, NORTH CAROLINA
100
l""'5iiiiiill
0 100
APPROXIMATE
SCALE IN FEET
200
FIGURE No. 1-8
-------------------~-~---
LEGEND
----BERM/ROAD ----
mUILliiltiiliiJII EXCAVATION
1111111 POSSIBLE SURFACE WATER
ORftJNAGE AREAS
8 OBSERVATION WELL
• SHALLOW MONITOR WELL
@ DEEP MONITOR WELL
0 OffSITE MONITOR WELL
,,,-21.J-' WATER LEVEL CONTOUR (II. AMSL)
,,,.-27.J-" EXTRAPOLATED WATER LEVEL .
CONTOUR (ft. AMSL)
0 SfC-001 (Appro•imo\e location)
-
ARMY CORPS
OF ENGINEERS
UST FARM
CDM FEDERAL PROGRAMS CORPORATION
11ubsidiary of Camp Dr~ncr & Md(cc Inc.
ro WILMINGTON
WATER LEVEL ELEVATIONS -May 7, 1991
NEW HANOVER COUNTY AIRPORT BURN PIT SITE
WILMINGTON, NORTH CAROLINA
~ ! -N-
~
100 0 100 200 !"""!I+=-
APPROXIMATE
SCALE IN FEEl
FIGURE No. 1·9
Permanent Wells
MWS-001
MWD-001
MWS-002
MWD-002
MWS-003
MWS-004
Temporary Wells
WL-1
WL-2
WL-3
WIA
WL-5
WL-6
WL-7
WL-8
OW-I
OW-2
OW-3
OW-4
OW-5
~ Above Mean Sea Level
-Not Available
14.88 14.7-4.9
27.81 27.6-17.9
14.88 14.7-4.9
27.42 27.2-17.5
15.01 14.8-5.1
14.96 14.8-5.0
TABLE 1-1
WELL CONSTRUCTION AND WATER LEVEL DATA
NEW HANOVER COUNTY AIRPORT BURN PIT SITE
WILMINGTON, NORTH CAROLINA
33.99 31.16
6.20 33.50 31.10
5.72 33.34 30.51
5.72 5.68 33.27 30.48
5.84 5.94 33.31 30.61
4.94 5.04 32.33 29.58
27.30
27.62
27.55 27.59
27.47 27.37
27.39 27.29
28.47
28.15
28.46
28.00
28.11
28.18
28.52
28.39
27.30
27.31
27.32
27.44
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cm/sec. The clay unit is expected to slow or impede contaminant migration from the
upper surficial aquifer to the lower sand and limestone aquifer.
The sand and limestone aquifer below the clay unit is thought to be the Castle Hayne
Limestone Formation. The boring log of test boring TB-1 indicates that below the
clay unit there is a 5.5-foot thick layer of fine sand from 34.5 to 40 feet bis, a 2-foot
layer of sand and clay lenses from 40 to 42 feet bis, and an 18-foot thick layer of
medium to coarse sand from 42 to 60 feet bis. A sandy fossiliferous limestone was
encountered to 60 feet bis. The boring was terminated while still in the limestone at
65 feet bis. Because aquifer testing has not been performed in the lower aquifer, its
characteristics are unknown.
1.4 RESULTS OF PREVIOUS INVESTIGATIONS
1.4.1 REMEDIAL INVESTIGATION
A remedial investigation (RI) was conducted by EPA in 1991. Preliminary
remediation goals (PRGs) were developed for the site by EPA, setting compound-
specific concentration goals for site contaminants. PRGs were established for
groundwater and soil. The soil PRGs were intended to be protective of exposure via
both air and soil ingestion pathways. These criteria were used to determine if
contaminated soils had been completely excavated.
Based on the results of previous soil and groundwater confrrmation sampling, it was
determined that all the soils above the PRGs had been removed and that the extent of
contaminated groundwater required further delineation. Six permanent monitor wells
were installed in April of 1991. On April 17, 1991, the frrst round of samples was
collected and analyzed for VOCs, SVOCs, and metals. A second round of
groundwater samples was collected from the site on May 7, 1991. These samples
were collected to determine baseline conditions at the site since previous groundwater
1-21
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samples were obtained when the site had not yet stabilized from the installation and
development of the monitor wells. A third sampling round was conducted in
November, 1991. A summary of all the groundwater sampling results, including each
sampling round, is presented in Table 1-2. Analytical results for groundwater
samples from all three sampling rounds are presented in Appendix B.
1.4.2 BASELINE RISK ASSESSMENT
FPC conducted a human health and ecological assessment in April 1992 to assess the
potential risk from exposure to chemicals at the New Hanover County Airport Bum
Pit Site. The baseline risk assessment evaluated current conditions in the absence of
any further remedial action at the site. Since the PRPs for this site have completed
permanent remedial activities to remove contaminated soil and other waste materials,
the risk assessment addressed only post-remediation conditions for the site.
Human health risk was quantified for the present baseline conditions. Since there are
residents within a three-mile radius of the New Hanover County Airport Bum Pit Site
who obtain drinking water from private wells, and other area residents who obtain
drinking water from a local community well system, the potential exists for migration
of contaminants from the site to private drinking water wells. Although no drinking
water wells have been found to be impacted by groundwater contamination from the
site, the risk assessment quantified the future potential exposure to local residents via
consumption of contaminated drinking water and inhalation of contaminant vapors by
showering.
Soil, surface water, and fugitive dust are not expected to be significant pathways of
exposure at the New Hanover County Airport Bum Pit Site in its present condition.
Contaminated soil has been removed to achieve the PRGs established for the site
soils, limiting the potential for re-entrainment of contaminated dust or direct contact
1-22
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TABLE 1-2
GROUNDWATER DATA SUMMARY
NEW HANOVER COUNTY AIRPORT BURN PIT SITE
WILMINGTON, NORTH CAROLINA
Inorganic Elements
Aluminum 13/14 23,479.2 58,000.0
Barium 12/14 155.7 410.0
Beryllium 1/14 1.4 1.4
Calcium 14/14 15,835.7 38,000.0
Chromium 13/14 41.6 82.0
Cobalt 1/14 2.2 2.2
Copper 12/14 9.4 21.0
Iron 14/14 15,151.6 40,000.0
Lead 1/14 22.0 22.0
Magnesium 13/14 4,433. I 12,000.0
Manganese 13/14 153.1 490.0
Molybdenum 2/14 2.7 2.7
Nickel 12/14 33.2 110.0
NOTES:
'Treatment technique action level (EPA, 199 I).
References: 'North Carolioa Administrative Code (ISA NCAC !SC. 1500), 1989.
2Safe Driokiog Water Act, EPA, 1991.
50-200
1,000 1,000
I
50 50
1,000 l,3CXf
300 300
so 15'
·so 50
150 100
NHANF.509.017
Potassium 12/14
Sodium 14/14
Strontium 13/14
Titanium 14/14
Vanadium 13/14
Yttrium 7/14
Zinc 14/14
Purgeable Organic
Compounds
Benzene 12/20
Carbon Disulfide 1/20
Chloroform 8/20
1,2-Dichloroethane 2/20
Ethylbenzene 12/20
Toluene 9/20
Xylenes, total 13/20
NOTES:
'Treatment technique action level (EPA, 1991).
4,356.7
82,sos:o
199.6
107.8
33.7
10.4
27.7
46.8
1.8
1.9
3.6
17.9
5.2
28.3
TABLE 1-2
( continued)
11,000.0
260,000.0
640.0
310.0
73.0
17.0
62.0
110.0
1.8
3.4
4.4
43.0
14
82
References: 'North Carolina Administrative Code (15A NCAC lSC.1500), 1989.
'Safe Drinking Water Act, EPA, 1991.
5,000 5,000
1 5
0.19 100
0.38 5
29 700
1,000 1,000
400 10,000
NHANF509,0!7
Extractable Organic
Compounds
2,4-Dimethylphenol 6/14
Methyl ethyl ketone 1/14
2-Methylnaphthalene 3/14
3-or 4-Methylphenol 1/14
2-Methylphenol 4/14
Naphthalene 5/14
NOTES:
'Treatment technique action level (EPA, 1991).
27.5
64
13.7
2.9
4.4
13.9
TABLE 1-2
( continued)
54
64
19
2.9
6.1
21
References: 1North Carolina Administrative Code (ISA NCAC !SC. 1500), 1989.
'Safe Drinking Water Act, EPA, 1991.
170
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with contaminated soils. In addition, there are no permanent surface water bodies at
the site.
The chemicals of concern in groundwater at the site are benzene, chloroform,
chromium, 1,2-dichloroethane, ethylbenzene, and lead due to toxicity, frequency of
detection, and exceedance of water quality standards. Tentatively identified
compounds (TICs) were not evaluated quantitatively since there is a lack of certainty
in identification and absence of critical toxicity values (i.e., reference doses and slope
factors).
Based on the human health risk assessment, the estimated carcinogenic human health
risk for benzene, chloroform, 1,2-dichloroethane is 3 x 10·5, which is at the upper end
of the acceptable risk range of 1 x 104 to 1 x 10-0 as established by EPA. The
estimated carcinogenic risk is the summation of ingestion and inhalation risks
following exposure (FPC, 1992). Since chromium is not expected to volatilize, and is
not expected to be a carcinogen through ingestion, a carcinogenic human health risk
was not calculated for this chemical. Also, since toxicity criteria are not available for
lead, a carcinogenic human health risk was not calculated for this chemical either.
An endangered species survey performed at the site did not identify the presence of
endangered species of flora or fauna. Species diversity was limited due to poor
habitat suitability. The dominant observed fauna onsite were opossum, lizard, and
perching/songbird species. Flora diversity is typical for a coastal range area that has
undergone significant disturbance, remediation, and subsequent revegetation. No
endangered flora species were identified onsite (FPC, 1992).
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1.5 SITE RESTORATION OBJECTIVES FOR GROUNDWATER
Remedial action objectives for the New Hanover County Airport Bum Pit site are
evaluated in this section. To support the development of remedial action alternatives
for the site, risk-based cleanup goals (remediation criteria) were derived for chemicals
of concern in soil, groundwater, sediment, and surface water, as presented in the Risk
Assessment (FPC, 1992). General remedial action objectives are to meet regulatory
requirements and to protect human health and the environment.
Section 121 of CERCLA, as amended by SARA, requires that remedial actions at
Superfund sites comply with applicable or relevant and appropriate requirements
(ARARs) of federal and state laws. In this section, ARARs are presented followed by
the development of remedial action objectives for groundwater at the New Hanover
County Airport Bum Pit Site. Table 1-3 summarizes the estimated risk for state and
federal groundwater quality standards. Risk based goals are derived for each target
risk level of lxlo-4, lxl0-5, and lxlO.;; as recommended by EPA. Finally, the extent
of groundwater contamination exceeding cleanup goals was estimated.
1.5.1 APPLICABLE OR RELEVANT AND APPROPRIATE
REQUIREMENTS (ARARs}
The selected remedial action for the New Hanover County Bum Pit Site must be
protective of public health and the environment and attain ARARs. The
protectiveness of the remedial action for the soils is determined by comparing the
baseline risk assessment and the development of cleanup goals summarized in the Risk
Assessment (FPC, 1992). Selection of and compliance with ARARs are discussed
below.
The requirement that ARARs be identified and complied with the development and
implementation of remedial actions is found in Section 121(d)(2) of CERCLA,
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Benzene
Chloroform
Chromium
TABLE 1-3
GROUNDWATER QUALITY STANDARD BASED RISKS
NEW HANOVER COUNTY AIRPORT SITE
WILMINGTON, NORIB CAROLINA
0.001 0.005 3 X 10-7
0.00019 0.1 1 X 10-8
0.05 0.05 0.3b• d
1,2-Dichloroethane 0.00038 0.005 4 X 10-7
Ethylbenzene 0.029 0.7 0.008d
Lead 0.05 0.015 ___ c
NOTES:
2 x lo-6
7 x lo-6
0.3b,d
5 x lo-6
0.2d
___ c
• Risk estimated assuming groundwater concentration at NCAC standard or at MCL
and using exposure assessment methods described in Section 3.3.
b
d
Chromium is not carcinogenic by the oral route.
No toxicity criteria available.
Value based on potential for noncarcinogenic effects, < 1 will not cause adverse
effects.
1-28
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42 U.S.C. § 962l(d)(2). Section 12l(d)(2) requires that for any haz.ardous substance
remaining onsite, all federal and state environmental and facility siting standards,
requirements, criteria, or limitations shall be met at the completion of the remedial
action to the degree that those requirements are legally applicable, or appropriate and
relevant under the circumstances presented at the site.
Applicable requirements are those requirements specific to the haz.ardous substance,
location, and/or contemplated remedial action, that are, or will be, related to the site.
These requirements would have to be met under any circumstance. Relevant and
appropriate requirements are those requirements that address problems or situations
sufficiently similar to those encountered at the site, so that their use is well suited to
the site, but for which the jurisdictional prerequisites have not been met.
The degree to which these environmental and facility siting requirements must be met
varies. Applicable requirements must be met to the full extent required by the law.
However, pursuant to Section 12l(e) of CERCLA, no permits are required for
remedial actions that are to occur completely within the site boundaries. On the other
hand, only the relevant and appropriate portions of non-applicable requirements must
be achieved, and only to the degree that they are substantive, rather than
administrative, in nature.
Remedial actions must comply with several different types of ARARs. These are best
categorized in three groups:
•
•
Ambient or chemical-specific requirements are those based on health-
or risk-based values that establish an acceptable amount or
concentration of a chemical that may be found in, or discharged to, the
ambient'environment.
Action specific requirements are technology-or activity-based
requirements or limitations on actions taken with respect to haz.ardous
substances.
1-29
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• Location-specific requirements are limitations on the use of specific
locations, such as wetlands.
These are each discussed separately below.
Section 12l(d)(2) of CERCLA requires that state requirements be identified by the
state in a timely manner, that those requirements be promulgated and consistently
applied, and that the requirements be more stringent than their federal counterparts.
While ARARs are promulgated, enforceable requirements and other types of
information may be useful for designing the remedial action, or necessary for
determining what is protective of public health or the environment. Non-
promulgated, non-enforceable guidelines or criteria that provide useful information are
termed criteria "to be considered" (TBC). Best professional judgment is used to
evaluate TBCs.
ARARs apply to actions or conditions located onsite and offsite. Onsite actions
implemented under CERCLA are exempt from administrative requirements of federal
and state regulations, such as permits, as long as the substantive requirements of the
ARARs are met. Offsite actions are subject to the full requirements of the applicable
standards or regulations, including all administrative and procedural requirements.
Based on the CERCLA statutory requirements, the remedial actions developed in this
FS will be analyzed for compliance with federal and state environmental regulations.
This process involves the initial identification of potential requirements, the evaluation
of the potential requirements for applicability or relevance and appropriateness, and
finally, a determination of the ability of the remedial alternatives to achieve the
ARARs. The determination of whether an ARAR will be met by a remedial
alternative is discussed in Section 12.0 and summarized in Section 13.0.
1-30
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CHEMICAL-SPECIFIC ARARs
Chemical-specific ARARs include those laws and regulations governing the release of
materials possessing certain chemical or physical characteristics, or containing
specified chemical compounds (EPA, 1988). These requirements generally set health
or risk-based concentration limits or discharge limitations in various environmental
media for specific hazardous substances, contaminants, and pollutants. Examples
include drinking water standards and ambient air quality standards. Potential
chemical-specific ARARs are listed in Table 1-4.
ACTION-SPECIFIC ARARs
Action-specific ARARs are technology-based, establishing performance, design, or
other similar action-specific controls or regulations on activities related to the
management of hazardous substances or pollutants (EPA, 1988). An example
includes RCRA incineration regulations. Potential action-specific ARARs are
presented in Table 1-5 for groundwater.
LocATION-SPECIFIC ARARs
Location-specific ARARs are design requirements or activity restrictions based on the
geographical or physical positions of the site and its surrounding area. Examples
include areas in a flood plain, a wetland, or a historic site. Potential location-specific
ARARs are listed in Table 1-6.
1.5.2 WAIVERS
Superfund specifies situations under which the ARARs requirements may be waived
[40 C.F.R. 300.430(f)]. The situations eligible for waivers include:
1-31
NHANFSOO .013
FEDERAL
Safe Drinking Water Act
National Primary Drinking Water Standards
Maximum Ccmtaminant Level Goals
Clean Water Act
Water Quality Criteria
Rcaotircc Conaervntion and Recovery Act
(RCRA), as amended
RCRA Groundwater Protection
Comprehensive Environmental Response,
Compensation, and Liability Act of 1980
(CERCLA)
Clean Air Act
National Primary and Secondary Ambient
Air Quality Standards
National Emissions Standards for Hazardous
Air Pollutants (NESHAPs)
Occupational Safety and Health Administration
TABLE 1-4
POTENTIAL CHEMICAL-SPECIFIC ARAR.,
NEW HANOVER COUNTY AIRPORT BURN PIT SITE
WILMINGTON, NORTH CAROLINA
40 USC Section 300
40 CFR Part 141
Publication L. N" 99-399, 100
Stat. 642 (1986)
33 USC Section 1251-1376
40 CFR Part 131
42 USC 6905, 6912, 6924,
6925
40 CFR Part 264
42 USC 9601 et. oeq.
40 USC 1857
40 CFR Part SO
40 CFR Part 61
29 CFR 1910 Part 120
Establishes health-based standards for public water
systems (maximum contaminant lcvcla).
&tablisbc1 drinking water quality goals set at levels of
no known or anticipated adverse health effects.
Seta criteria for water quality based on toxicity to aquatic
organisms and human health.
Provides for groundwater protection standards, general
monitoring requirements, and technical requirements.
Provide, for response to hazardous substances released
into the environment and the cleanup of inactive
haurdou1 waste disposal 1ite1.
Seta primary and secondary air standards at levels to
protect public health and public welfare.
Provides emissions standard for hazardous air pollutants
for which no ambient air quality standard exists.
Provides safety rules for handling specific chemicals for
site workers during remedial activities.
The MCLI for organic and inorganic contaminanta
are applicable to the groundwater contaminated by
the site since it is a drinking water source.
Proposed MCLG1 for organic and inorganic
contaminants arc applicable to the groundwater
used for drinking water.
The AWQC for organic and inorganic
contaminanta are relevant and appropriate.
The RCRA MCI.a arc relevant and appropriate for
groundwater at the site.
Applicable to the New Hanover County Bum Pit
Site.
May be relevant or appropriate if onsite treatment
units arc part of remedial actions.
May be relevant or appropriate if onsitc treatment
unita arc part of remedial actions.
Health and safety rcquircmellts arc applicable to
all potential remedial actions.
NRANPS9B.OOI
STATE
North Carolina Drinking Water Act
North Carolina Drinking Water and
Groundwater Standard.a
130A NCAC 311-327
!SA NCAC Chaptor 2L
TABLE 1-4
(continued)
Regulates water systems within the state that supply
drinking water that may affect the public health.
Establishes groundwater classification and water quality
ltandards. Applicable to groundwater at the site.
Provides the atatc with the authority needed to
assume primary enforcement responsibility under
the federal act.
Guideline, for allowable· lcvclt of toxic organic
and inorganic compounds in groundwater used for
drinking water. Applicable to groundwater at the
site.
NKANFS9B.001
---- --- - - - - - - - - ---l!!!!!-c=-iii!i!-~=--=--=~-=-=-=TAB==LEl-5 =-=--==--~
FEDERAL
Groun.dwaur &traction and Treatment
Rcsoun:c Conservation and Recovery Act (RCRA), as amended
Identification of Hazardous Waste
Treatment of Hazardous Wastes in a Unit
Requirementa for Generation, Storage, Transportation, and
Dispoaa.l of Hazardous Waste
Safe Drinking Water Act (SOWA)
Primary Maximum Contaminant Levels (MCL)
Maximum Contaminant Level GoaJs (MCLG)
Disposal -Discharge to Surface Water/POTW
Clean Water Act (CW A)
Requires use of Best Available Treatment Technology
(BACI)
National PoUutant Diachargc Elimination System Permit
Regulations
Discharge must be consistent with the requirements of a
Water Quality Management Plan approved by EPA
Discharge must not increase contaminant concentrations in
off site surface water.
Super-fund Amendments and Reauthorization Act (SARA)
POTENTIAL ACTION-SPECIFIC ARAlu FOR GROUNDWATER
NEW HANOVER COUNTY AIRPORT BURN PIT SITE
Wll.MINGTON, NORTH CAROLINA
42 USC Section 6901 ct. aeq.
40 CFR261
40 CFR 264.601
40 CFR 265 .400
40 CFR263
40 CFR264
42 USC Section 3001 et. seq.
40 CFR 142
40 CFR 142
50 FR 46936
(November 13, 1985)
33 USC Section 1351-1376
40 CFR 122
40 CFR 122 Subpart C
40CFR 122
Section 121 (d)(2)(B)(liQ
42 USC Section 9801 et. seq.
Federal requirements for classification and ~dentification of hazardous wastea.
Rules and rcquircmenta for the treatment of hazardous wastes.
Regulates storage, transportation, and operation of hazardous waste generaton.
Primary MCI.a arc adopted for the protection of human health but include an analysia of feasibility
and cost of attainment.
EPA baa also established Maximum Contaminant Level Goals (MCLGs). The nonenforceable
standards arc based on health criteria. The MCLGa arc goals for the nation's water supply.
Use of beat available technology economically achievable is required to control discharge of toxic
pollutants to POTW.
Use of best available technology economically achievable for toxic pollutants discharged to surface
watcn.
Discharge must comply with EPA-approved Water Quality Management Plan.
Selected remedial action must establish a standard of control to maintain surface water quality.
Discharge must comply with Federal Water Quality Criteria.
NHANFm.001
STATE
North Carolina Water Quality Standards
North Carolina Groundwater Standards
Wastewater Discharge to Surface Watcn
North Carolina Air Pollution Control Requirement,
City of Wtlmington POTW Discharge Criteria
NCAC -15A-2B
NCAC -15A-2L
NCAC -15A-2H
NCAC -15A-2D
Article m
Section 12-76 to 12-162
Surface water quality standards.
Groundwater quality standards, regulates injectiOn wells.
Regulates surface water discharge and discharges to P0TW.
Air pollution control air quality and emissions standards.
Minimum quality standards for disposal to the Northsidc POTW.
-----
FEDERAL
Resource Conservation and Recovery Act
(RCRA), as amended
RCRA Location Standards
Fish and Wildlife Coordination Act
Floodplain Management
Executive Order
Endangered Species Act
Clean Water Act
Dredge or Fill Requirements
(Section 404)
Riven and Harbon Act of 1889
(Section 10 Permit)
Wtldcmeaa Act
National Wildlife Refuge System
--
42 use 6901
40 CFR 264.18(b)
16 USC 661-666
- - - - -
TABLE 1-6
POTENTIAL LOCATION -SPECIFIC ARARs
NEW HANOVER COUNTY AIRPORT BURN PIT SITE
WllMINGTON, NORTH CAROLINA
-
A TSD facility must be designed, constructed, operated, and
maintained to avoid washout on a 100-year floodplain.
This regulation requires that any federal agency that proposes
to modify a body of water must consult with the U.S. Fish
and Wtldlifc Services. This requirement is addressed under
CW A Section 404 Requiremects.
---~-=---
Potcnlial remedial alternatives with.in the 100-ycar
floodplain. Requirement is relevant and appropriate.
Potential remedial alternatives may include stream
redirection during sediment dredging activities.
Potentially relevant and appropriate.
Executive Order 11988;
40CFR6.302
Actions that aro to occur in floodplain should avoid adverse
effects, minimize potential hann, restore and pre1ervc natural
and beneficial value.
Remedial actions arc to prevent incursion of
contaminated groundwater onto forested floodplain.
16 use 1531
33 USC Section 1251
40CFR230
33 USC Section 403
16 USC 1311
16 use 688
50 CFR 27
Requires action to conserve endangered species or threatened
apecics, including consultation with the Department of
Interior.
No threatened or endangered species or critical habitata
were identified in or near the site.
Requires pennit for discharge of dredged or fill material into No alternative will be developed which will discharge
aquatic environment. dredge or fill material into an aquatic environment.
Requires pcnnit for structures or work. in or affecting No alternative involves work that would affect a
navigable waters. navigable waterway.
Arca must be administered in such a way as will leave it un-No wilderness areas exist onaite or adjacent to the site.
impaired as wilderness and will preserve it as a wilderness.
Restricts activities within National Wildlife Refuges. No wildlife refuge area exist onsite or adjacent to the
site.
NHANFm.001
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1.5.3
Interim remedies,
Remedies in which attainment of the ARAR would pose a greater risk
to human health or the environment than would nonattainment,
Technical impracticability of attainment,
Inconsistent application or enforcement of a state requirement,
Fund balancing (financial restriction within the Superfund program), or
Attainment of equivalent performance without the ARAR.
MEDIA OF CONCERN
Based on the results of the remedial investigation and the baseline risk assessment, the
New Hanover County Airport Bum Pit Site is comprised of only one contaminated
medium. Because the contaminated soil at the site has been excavated and removed,
groundwater is the only contaminated medium.
1.5.4 REMEDIAL ACTION OBJECTIVE
Considering the requirements for risk reduction discussed in the Baseline Risk
Assessment (COM, 1992), the risk-based cleanup goals derived, and the ARARs
discussed in Section 1.5.1, the remedial action objectives specifically developed for
the groundwater at the New Hanover County Airport Bum Pit Site are presented in
Table 1-3.
To obtain cleanup criteria for the New Hanover County Airport Bum Pit Site, FPC
used the applicable or relevant and appropriate requirements (ARARs) for this site,
including the North Carolina Drinking Water Quality Standards and federal Safe
Drinking Water Act (SOWA) Maximum Contaminant Levels (MCLs), for each
chemical of concern. The most conservative of these values were selected as the site-
specific cleanup goals as previously presented in the risk assessment (FPC, 1992). In
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addition, human ingestion and inhalation risks were estimated for each selected
cleanup goal.
1.5.5 EXTENT OF GROUNDWATER CONTAMINATION
The most conservative ARARs were selected to estimate the contaminant plumes for
each chemical of concern. Contaminant plume aerial extents were extrapolated
toward the north, east, and west of the bum pits due to lack of groundwater quality
data in this area. To better refine the extent of contamination, several additional
monitor wells should be installed on the north, east, and west sides of the bum pits.
The extent of groundwater contamination is a combination of the three separate
plumes for benzene at 1 µ.g/1, chromium at 50 µ.g/1, and chloroform at 0.19 µ.g/1, and
ethylbenzene at 29 µ.g/1 as shown on Figures 1-10, 1-11, 1-12 and 1-13, respectively.
Because lead was each found in well MWS-001 in one sampling round only, and 1,2-
dichloroethene was detected only in MWD-002 in two sampling rounds (and since
these two wells are within the total areal extent of groundwater contamination),
specific plumes were not estimated for these compounds. The approximate horiwntal
extent of contamination was estimated by overlaying the individual contaminant
plumes for benzene, chromium, chloroform and ethylbenzene and is shown on
Figure 1-14. The vertical extent of contamination extends throughout the 28 feet of
the surficial aquifer. The approximate volume of contaminated water is 9,694,080
gallons, based on a porosity of 0.20.
1-38
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---------------------
LEGEND
----BERM/ROAD ----
rTflllliiilliiil!ITr EXCAVATION
llllllil POSSIBLE SURfACE WATER
DRANAGE AREAS
0 TEMPORARY MONITOR WELL
• SHALLOW MONITOR WELL
@ DEEP MONITOR WELL
J ESTIMATED VALUE
NO NOT DETECTED
.,.-25.5...,,,. CONCENTRATION CONTOUR (ug/1)
, .. 25,5 ..... EXTRAPOLATED CONTOUR {ug/1)
ARMY CORPS
OF ENGINEERS
UST FARM
NOTE: 1 ug/I is the North Carolina
Water Quo lily. Standard.
100
TO WILMINGTON
EXTENT OF BENZENE CONTAMINATION IN THE SURFICIAL AQUIFER (ug/1)
NEW HANOVER COUNTY AIRPORT BURN PIT SITE
CDM FEDERAL PROGRAMS CORPORATION
a ,ut.idwy of Camp Dn:uu &. McKee Inc. WILMINGTON, NORTH CAROLINA
0 100
APPROXIMATE
SCALE IN FEET
200
FIGURE No. 1-10
LEGEND
----BERM/ROAD ----
fTTTl"'"'""""r EXCAVATION
11!1111 POSSIBLE SURFACE WATER
DRAlNAGE AREAS
0 TEMPORARY MONITOR W[ll
• SHALLOW MONITOR WELL
@ OEfP MONITOR WELL
NA NOT ANALYZED
,-50_,,,. CONCENTRATION CONTOUR ("g/1)
, .. 50 .. , EXTRAPOLATED CONTOUR ("g/1) ·
ARMY CORPS
OF ENGINEERS
UST FARM
J
' NOTE: 50 ug/1 is the SOWA MCL.
100 II
10 WILMINGTON
0 100
APPROXIMATE
SCALE IN FEET
~ APPROXIMATE EXTENT OF CHROMIUM CONTAMINATION IN THE SURFICIAL AQUIFER (ug/1)
ll!Wliil NEW HANOVER COUNTY AIRPORT BURN PIT SITE .
200
~? .. ~~?i!~.!:R:~1!~!1s CORPORATION . WILMINGTON, NORTH CAROLINA FIGURE No. 1-11
LEGEND
fTT'"'"'"'"""r
11111111
~
•
@
J
ND
,,,-0.19_.
... -0.19 .. ,
BERM/ROAD
EXCAVATION
POSSIBLE SURFACE WATER
ORANAGE AREAS
TEMPORARY MONITOR WELL
SHALLOW MONITOR WELL
OEEP MONITOR WELL
ESTIMATED VALUE
NOT OETECTEO
CONCENTRATION CONTOUR ( uq/1)
EXTRAPOLATED CONTOUR (uq/1) /,
// I/ 1/
II
I
ARMY CORPS
OF ENGINEERS
UST FARM
NOTE: 0.19 ug/1 is the North Carolina
Waler Quality Standard.
100
TO WILMINGTON
0 100
APPROXIMATE
SCALE IN FEEi
200
APPROXIMATE EXTENT OF CHLOROFORM CONTAMINATION IN THE SURFICIAL AQUIFER (ug/1) ~ NEW HANOVER COUNTY AIRPORT BURN PIT SITE CDM FEDERAL PROGRAMS CORPORATION
a •11t.idwy o(Cunp lln:Hcr & Mc~c Inc. WILMINGTON, NORTH CAROLINA FIGURE No. 1·12
LEGEND
,,.,,, .. ,,, .... ,,""
•
@
J
ND
NS
,,,..-29 _,,
,, .. 29 .. ,
BERM/ROAD
EXCAVATION
POSSIBLE SURfACE WATER
DRAINAGE AREAS
TEMPORARY MONITOR WELL
SHALLOW MONITOR WELL
DEEP MONITOR WELL
ARMY CORPS
OF ENGINEERS
UST FARM
NOTE: 0.19 ug/I is the North Corolino
Water Ouolity Standard.
It
/1
11
\\
\\
\\ ,,
\\ TO WILMINGTON
100
! -r
0 100
APPROXIMATE
SCALE IN FEET
200
~ APPROXIMATE EXTENT OF ETHYLBENZENE CONTAMINATION IN THE SURFICIAL AQUIFER (ug/1) ~ NEW HANOVER COUNTY AIRPORT BURN PIT SITE
CDM FEDERAL PROGRAMS CORPORATION
• subsidia')' of. Camp Dr-& Mcltc,,:i b:. WILMINGTON, NORTH CAROLINA FIGURE No.1-13
-
LEGEND
m,11n11n11mor
•
@
,--'
BERM/ROAD
EXCAVATION
POSSIBlI · SURFACE WATER
DRANAGE AREAS
TEMPORARY MONITOR WELL
SHALLOW MONITOR WELL
DEEP MONITOR WELL
APPROXIMATE LIMITS OF
GROUNDWATER CONTAMINATION
ARMY CORPS
OF ENGINEERS
UST FARM
100
TO WILMINGTON
0 100
APPROXIMATE SCAI.£ IN FEET
APPROXIMATE TOTAL EXTENT OF CONTAMINATION IN THE SURFICIAL AQUIFER
NEW HANOVER COUNTY AIRPORT BURN PIT SITE
200
CDM FEDERAL PROGRAMS CORPORATION
a~ cl.Camp Dr-A Mc.K,:,,:, Im:.
WILMINGTON, NORTH CAROLINA FIGURE No. 1-14
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2.0 IDENTIFICATION, SCREENING, AND EVALUATION OF
TECHNOLOGIES AND PROCESS OPTIONS
This section presents the identification and screening of corrective action technology
types and process options applicable to the New Hanover County Airport Burn Pit
Site. The area to be addressed through groundwater remediation ( discussed in
Section 1.5) was considered throughout the development of applicable technologies.
Potential technologies for long-term extraction, treatment, containment, and discharge
were identified and screening was conducted to eliminate infeasible or impractical
extraction, treatment, containment and/or disposal options.
General response actions for groundwater remediation include several extraction,
treatment, containment, and disposal options. Technologies within these categories
have been considered for dissolved constituents in groundwater at the site. A
preliminary screening of technologies was conducted on the basis of technical
implementability by reducing the universe of potentially applicable technologies.
Those technologies that can be technically implemented at the site were further
evaluated on the basis of effectiveness, implementability, and cost.
Those technologies retained for groundwater remediation at the site have been
combined to form site-wide remedial action alternatives, which are presented in
Section 2.4 and discussed in detail in Sections 3.2 through 3.6.
2.1 SCREENING OF GROUNDWATER TECHNOLOGIES
AND PROCESS OPTIONS
The preliminarily identified technology types and process options applicable to
groundwater remediation at the New Hanover County Airport Burn Pit Site are
presented in Table 2-1. As shown, several entire technology types and process
2-1
NHANFS09 .001
Groundwatar General
Response Actions Remedial Technology
INITIAL SCREENING OF TECHNOLOGIES AND PROCESS OPTIONS
NEW HANOVER COUNTY AIRPORT BURN PIT SITE
WILMINGTON, NORTH CAROLINA
Process Optlon Description
..._I _No_k_tio_n_-----'1--.... / _No_ne ______ 1----._j _No_t_appli_;_.:_icabl __ e ____ _ No action
A£cess restrictions Deed restrictions lnstiMional
actions Monitoring 1---~ Groundwater monitoring L__ _ _:_ ___ __J
SlulJY wall
Containment --Vertical barriers ~--------' Grout curtain
Sheet pllilg
Extraction weDs
Colection 1-.... ~ Extraction
Treatment
(586 flllXI page}
Discharge
/586 flllXI page I
/586 flllXI page I
P ,,,,, ''ial Process option eliminated ·from further consideratlon
Deeds for property in the area of influence
would include restlictions on wells
Ongoing monitoring wells
Trench around areas of contamination is filled
with a soil (or cement) bentonite slUIJY to form
an impermeable barrier
Pressure injection of grout In a regular pattern
of dnlled holes to form an impermeable barrier
Lengths of steel sheets are connected together
and driven Into the ground to form an
Impermeable barrier
Series of wells to extract contaminated
groundwater
Injection wells Inject uncontaminated
water to Increase flow ti extraction wells
Per1orated pipe In trenches backfilled with
porous rneda k> collect contaminated water
System of Injection and extraction wells Introduce
bacteria and nutrients to degrade contamination
System ol wells to Inject air Intl groundwater to
rem0'18 volables by air s!JWlng
Downgradlent trendies backfilled with actlvaled
carbon k> r81110W1 contaminants from water
System of Injection wells k> Inject oxidizer such
as hyltogen peroxide to degrade contaminants
Screening Comments
Required for consideration by NCP
Potentially applicable
Potentially applicable
Potentially applicable
Potentially applicable
Potentially applicable
Potentially applicable
Not feasible because NCDNR
prohibits Injection wells
Not feasible for Intercepting contaminated
groundwater because of vertical depth
of 28 feet bis
Not feasible because of low concentrations of
organic contaminants and Ineffectiveness In
removing Inorganic contaminants
Not feasible because of potential for wlatizlng organic
contaminants and recontaminating dean soils and
Ineffectiveness in removing inorganic contaminants
Not feasible because of Ineffectiveness In remO'<lng
Inorganic contaminants
Not feasible because of potential for wlatizlng organic
contaminants and recontaminating dean soils and
Ineffectiveness In removing inorganic contaminants
Groundwalar General
Response Actions Remedial Technology Process Option
Precipitation _
Air Stripping Collection /see
previous page}
Treatment/see
previous page}
Physical/Chemical
-...-i treatment --~ Camon adsorption
Discharge
Offslte treatment
Onsite discharge
Offslte discharge
k ·' -'' ?: I Process option eliminated from further consideration
Ion exchange
ChromiJm Reduction
Hazardous Wastewater
Treatment Facility (TSO)
Spray irrigalbn
POTW
Plpellne to surface water
TABLE 2-1 (Continued)
Description
Alteration of chemical equilibria to reduce
solubility of the contaminants
Mixing large volumes of air with water In a
packed column to promote transfer of VOC's to air
Adsorption of contaminants onto _activated cart>on
by passing water through cart>on column
Screening Comments
Potentially applicable
Potentially applicable
Potentially applicable
Use of high pressure to force water through a Contaminant concentrations too low for
membrane leaving contaminants behnd treatment
Contaminated water is passed through a resit bed Potentially applicable
where ions are exchanged between resin and water
Reduction of Cr" to Cr" followed by Cr" removal Potentially applicable
through h)'ltoxlde precipitation
Extracted groundwater transported to a TSD facility Not feasille due to excessive cost
for treatment ·
Degradation of 01gank:s using microorganisms
in an aerobic environment
Degradation of 01gank:s using microorganisms
in an aerobic environment
Injection wells inject extracied and treated
water into aquifer
Extracted and treated water discharged to
onslte Infiltration basins
Extracted and treated water discharged through
perforated pipe In trenches backfilled with
porousmeoa
Extracted and treated water discharged through
plant ~lake and~ (evapotranspiation)
and percolation through soil
Extracted and treated water dischared to City of
Wilmington Northslde POTW for treatment
Extracted and treated water discharged to
Smith Creek
Not applicable as organic contaminants are more
volatile than biodegradable at the site
Not applicable as organic contaminants are more
volatie than biodegradable at the site
Not feaslille because NCDNR prohiJits
Injection wells
Not feaslille because of shallow groundtlater
table and expected moundng effects
Not feaslille because of shallow groundwater
table and expected moundng effects
Potentially applicable
Potentially appl"icable
Potentially applicable
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options are eliminated from further consideration solely on the basis of technical
implementability or cost effectiveness at this specific site. The retained technologies
are further evaluated in Section 2.2.
The no action technology was retained to be combined with the groundwater
monitoring process option. The no action alternative is further evaluated in
Section 3.0. In addition, deed restrictions are also considered for each alternative
evaluated in Section 3.0.
2.2 EVALUATION OF TECHNOLOGIES AND PROCESS OPTIONS
The following sections present a detailed description and an evaluation based on
effectiveness, implementability, and cost for each of the retained remedial
technologies and associated process options under the groundwater containment,
collection, treatment, and discharge response actions.
2.2.1 CONTAINMENT TECHNOLOGIES
The containment process options under evaluation consist of three types of vertical
barriers: slurry wall, grout curtain, and sheet piling. Because initial screening
indicated all three options are potentially applicable to the site, one will be selected
for the purpose of developing and evaluating site-wide alternatives. However, if an
alternative involving containment were to be selected for implementation at the site,
these process options should be evaluated in detail during the remedial design phase
of the project.
Slurry Wall
Containment of the contaminant plume can be achieved through plume encapsulation
by placing an impermeable slurry wall at the limits of the plume. In this method, a
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trench is excavated in the presence of a bentonite-water slurry beyond the, depth of the
plume. After excavation is complete, the trench can be backfilled with a mixture of
the excavated material and bentonite, or a cement-bentonite mixture. This technique
is an effective method of creating an impermeable barrier to prevent further migration
of the contaminant plume. The slurry wall would have to extend over the entire
perimeter of the plume, approximately 1,600 feet in length, and to a depth of at least
30 feet bls. This approach can be implemented using standard engineering techniques
and methods. An impermeable cap will be required in ·conjunction with the slurry
wall to minimize the potential of groundwater mounding at the site.
Grout Curtain
Because of the sandy soil conditions at the site, the grout curtain process option seems
to provide a viable alternative to the slurry wall and other vertical wall technologies.
However, because of the presence of the organic and inorganic contaminants in
groundwater, proprietary fixation chemicals would have to be injected to ensure the
presence of an impermeable barrier. This technology relies on boring head that
includes five in-line drill bits powered by submersible motors. The entire boring head
is suspended by cables from a conventional construction crane. The barrier wall
chemicals are supplied under low pressure through the auger head and mixed during
extraction. The low pressure prevents the grout outflow that is· common with
conventional injection methods. An impermeable cap will be required in conjunction
with the grout curtain to minimize the potential for groundwater mounding at the site.
Because this technology is innovative with respect to the groundwater chemical
environment present at the site, the cost of implementing this technique would be very
high compared to that of a slurry wall. Therefore, the grout curtain process option is
eliminated from further consideration.
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Sheet Piling
This technology involves driving lengths of connected steel sheets into the ground to
form an impermeable barrier. Steel is the best form of sheet pile, compared to wood
and concrete) since corrosion has not been shown to be a factor in causing failures.
Initially, sheet piles are not totally impermeable; however, after a period of time,
gaps in the sheet pile connections are formed as fine particles in the groundwater clog
the gaps (Knox, et al., 1986). To date, use of sheet piling has been proposed to
control groundwater pollution, but few specific applications have been conducted
(Knox, et al., 1986). An impermeable cap would be required in conjunction with the
sheet piling to minimize the potential for groundwater mounding at the site.
Although sheet piling can be an effective technique for groundwater containment and
it could be easily implemented, its cost would be high when compared to the slurry
wall process option. Due to relatively high costs and a limited history of use, sheet
piling is eliminated from further consideration.
2.2.2 EXTRACTION TECHNOLOGY
Removal of the groundwater contaminant plume can prevent contaminant migration
offsite. The principal means of optimizing contaminated groundwater recovery is
through the alteration of the groundwater gradient to enhance and/or control
contaminant movement. This can be accomplished by placing an extraction system
downgradient of the contaminated area or artificially influencing an existing gradient
via groundwater extraction.
The reduction of contaminant concentrations over time is the primary indicator of the
effectiveness of an extraction system for aquifer restoration. The ideal scenario
would be a steady decrease in contaminant concentrations until the target level is
attained. However, performance records suggest that although concentrations may
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drop initially, decline is often followed by a leveling of concentrations with little or
no further decrease over time (EPA, 1989).
Extraction wells are commonly used as an extraction method to influence groundwater
flow and recover dissolved constituents. Extraction wells are used to contain the
migration of a contaminant plume or reduce its size, and would be located
downgradient of the original source area, surrounding the burn pits. In general,
extraction wells are versatile under a variety of site conditions and have design and
operating flexibility. Although single or multiple wells can be used to sufficiently
contain the spread of the dissolved constituent plume, multiple wells should be
positioned in such a way that the cones of influence overlap. Due to their ease of
installation, effectiveness at other groundwater remediation sites, and low capital and
· maintenance costs, extraction wells will be retained for further consideration.
2.2.3 TREATMENT TECHNOLOGIES
A review of the retained process options, all of which are representative of
physical/chemical treatment technologies, was conducted to determine the most
appropriate treatment process for the removal of dissolved organic and inorganic
contaminants in the groundwater. As discussed previously in this report, the organic
chemicals of concern are benzene, chloroform, 1,2-dichloroethane, and ethylbenzene.
Lead and chromium are the inorganic chemicals of concern present in groundwater at
concentrations above cleanup criteria, although required removal efficiency will be
dictated by the selected discharge option. Applicable treatment options include
precipitation, air stripping, carbon adsorption, ion exchange and chromium reduction,
included as a contaminant-specific treatment option to enhance removal of hexavalent
chromium (Cr+6), in the event it is present at the site. These process options are
described and evaluated below. Because initial screening indicated all five process
options are potentially applicable to the site, specific combinations of options will be
selected for the purpose of developing and evaluating sitewide alternatives. However,
2-7
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if an alternative involving physical/chemical treatment were to be selected for
implementation at the site, these process options should be evaluated in detail during
the remedial design phase of the project.
Precipitation
Precipitation involves the addition of a treatment chemical (i.e., sodium hydroxide,
calcium hydroxide, hydrochloric acid, sulfuric acid, sodium sulfide) to vary pH and
transform a contaminant from the dissolved to the solid (salt) form so that it can be
removed by clarification and/or filtration. Metals removal is the most common
application of the precipitation process. The treatment agent may chemically alter the
contaminant, or it may create a more rapidly settling material. In the case of metal
ions, a treatment chemical is added to the wastewater, forming relatively insoluble
compounds (generally hydroxides or sulfides) with the metal ions present. The degree
to which any dissolved metal is precipitated depends on the solubility of the resultant
metal hydroxide or sulfide (which is generally pH dependent) and on the pH at which
the process is operated. Usually, the insoluble compounds are then flocculated with
polyelectrolytes, to aid in clarification, and settled out of solution in a clarifier. A
properly designed and operated precipitation system can result in effluent metals
concentrations ranging from 10 to 100 µg/1, depending on influent loadings and the
solubility of the metal salt. Filtration reduces the levels even further by removing
residual suspended solids.
Since the treatment system at the New Hanover County Airport Bum Pit Site must
address two different metals (chromium and lead), bench-scale treatability studies
should be conducted to select the appropriate treatment chemical and optimize the pH
for effective removal of all three metals, to define design criteria for clarification and
to determine if filtration will be necessary to meet discharge limitations. Table 2-2
presents optimum treatment pH values for the metals of concern at the site.
2-8
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TABLE 2-2
OPTIMUM TREATMENT pH VALUES
NEW HANOVER COUNTY AIRPORT BURN PIT SITE
WILMINGTON, NORTH CAROLINA
Chromium, trivalent
Lead
NOTE:
7.5
9
101 9.8
10 8
10.0
10
1Considerable disagreement exists regarding the effect of pH on the solubility
of chromium hydroxide.
Source: J.W. Patterson, 1985.
2-9
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The precipitation process generates a significant volume of solids because it does not
effectively distinguish between the chemical of concern and other easily precipitated
\
ions, such as calcium and iron. Proper management of these solids is necessary in
order to prevent short-or long-term negative impacts to the environment. Any design
must also include provisions for the proper handling of the treatment chemicals.
Precipitation (along with required clarification and filtration) is a proven technology in
removing the indicator metals at the site and is retained for further evaluation.
Air Stripping
Air stripping towers have been used effectively for removing of dissolved VOCs from
groundwater. A typical air stripping tower is shown in Figure 2-1. Contaminated
water enters the stripping tower at the top and is evenly distributed across the internal
packing media through distributor nozzles. Clean air is introduced into the bottom of
the tower below the packing using a forced air blower, and flows upward through the
packing. As the falling contaminated water flows countercurrent to the rising air
stream, VOCs are stripped from the water and enter the air stream. These organics
are carried by the air stream out of the tower to the atmosphere. The internal packing
media acts to increase the total surface area available for mass transfer of the organic
contaminants from the liquid to the vapor stream. Treated water falls from the
packing into the stripper basin and exits the tower as contaminant-free water. Since
contaminant levels in groundwater are fairly low, it is likely that further treatment of
off-gases from air stripping will not be required; however, off-gas concentrations
should be calculated during the preliminary design stage to determine the need for
treatment in order to meet state and federal air quality regulations.
The extent of compound removal by air stripping is governed by many factors,
including contaminant concentrations in groundwater, air and water temperatures, the
air-to-water ratio, and contaminant physical properties. One such physical property is
2-10
NHANFS09.001
EXHAUST AIR
WATER DISTRIBUTION
NOZZLES OR
DISTRI.BUTION PLATE
PACKING MEDIA
AIR BLOWER
t TO ATMOSPHERE
INFLUENT WATER
FROM
CONTAMINATED
WELL
,..,.-TREATED WATER
TYPICAL AIR STRIPPING TOWER
-NEW HANOVER COUNTY AIRPORT BURN PIT SITE ~~--------CDM FEDERAL PROGRAMS CORPORATION WILMINGTON, NORTH CAROLINA . FIGURE No. 2·1
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the Henry's Law constant. Henry's Law states that the partial pressure of a
compound (a measure of the concentration in the gas phase) at equilibrium is equal to
a constant (Henry's Law constant) multiplied by the concentration of the compound in
the liquid phase. The Henry's Law constant is a partition coefficient that describes
the relative tendency for the compound to partition between the gas and liquid phases
at equilibrium conditions. The larger the Henry's Law constant, the greater the
equilibrium concentration of the contaminant in the air phase. High Henry's Law
values indicate compounds that are more easily removed from solution than those
having lower values. Volatile compounds typically have dimensionless Henry's Law
constants greater than 0.1 (Patterson, 1985).
The Henry's Law constant for both benzene and 1,2-dichloroethane is 0.23 and for
chloroform is 0.14 (Patterson, 1985). As shown in Table 2-3, benzene, chloroform,
1,2-dichloroethane, and ethylbenzene should be easily removed by air stripping due to
high Henry's Law constants.
Air stripping tower performance also depends largely on the presence or absence of
various inorganic compounds and suspended solids in the groundwater. Groundwaters
with elevated hardness will result in calcium and magnesium salt deposits in the tower
packing media. Elevated iron concentrations, when oxidized in the air stripper, will
result in iron hydroxide precipitation, which can severely foul the packing media and
reduce its effectiveness to remove VOCs. In addition, elevated total suspended solids
(TSS) concentrations in the groundwater can also result in solids deposition on the
tower packing and reduce liquid-to-air mass transfer. Groundwater at the New
Hanover County Airport Burn Pit Site apparently contains relatively high
concentrations of iron (up to 40 ppm have been reported in site monitor wells) and
may contain moderately high concentrations of TSS, which are unreported for the
site. The use of air stripping would require pretreatment to remove iron and TSS.
2-12
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TABLE 2-3
HENRY'S LAW CONSTANTS FOR VOLATILE COMPOUNDS OF CONCERN
NEW HANOVER COUNTY AIRPORT BURN PIT SITE
WILMINGTON, NORTH CAROLINA
Benzene
Chloroform
1,2-Dichloroethane
Ethylbenzene
NOTES:
0.231
0.142
0.231
0.271
1 Source: James W. Patterson, 1985, pp. 320-322.
2 Experimentally determined values (Moore, 1976).
2-13
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Pretreatment equipment could consist of clarification/equalization basins or
multi-media filters to remove TSS followed by greensand filters to remove iron.
Multi-media filters remove suspended particles by filtration using several layers of
filter media, usually consisting of coarse anthracite coal above various gradations of
finer silica sand. When the filter bed becomes loaded with suspended matter, it is
backwashed with treated water to remove the solids deposited on the filter media. In
the case of greensand filtration, dissolved iron is oxidized to the insoluble iron
hydroxide form by contact with a chemically treated filter media called manganese
greensand. The insoluble iron hydroxide along with particulate iron in the
groundwater is then filtered by the greensand media, and removed by backwashing.
When the oxidizing capacity of the greensand media is exhausted, the filter bed is
regenerated with a weak potassium permanganate solution, thus restoring the
oxidizing capacity of the bed.
An alternative approach to pretreatment equipment may be the use of proprietary
chemical complexing agents that prevent iron from precipitating in the air stripping
tower combined with more innovative "lower profile" towers and/or trayed towers
that reduce the total surface area available for fouling. In these stripping towers,
slotted trays and/or customized baffles are used to achieve the appropriate liquid-to-air
mass transfer instead of conventional packing media. The need for pretreatment
should be explored during the remedial design phase and the appropriate combination
of pretreatment steps identified.
Air stripping is an effective and relatively low-cost process option to remove VOCs
from groundwater and is therefore retained for further discussion.
Carbon Adsorption
A second process option for organics removal from groundwater is activated carbon
adsorption. This option is widely used for the removal of both volatile
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and non-volatile organic compounds. Activated carbon adsorption is most often
carried out in a pressurized vessel that contains a bed of granular activated carbon.
Figure 2-2 shows a typical activated carbon filter. Contaminated water enters the
pressurized vessel at the top and is evenly distributed over the granular activated
carbon. As contaminated water flows downward through the activated carbon media,
organic compounds are adsorbed onto the microporous surfaces of the activated
carbon by an electrical attraction. When the microporous surfaces of the carbon
become saturated with adsorbed organics, the carbon must be replaced with new or
thermally regenerated carbon media. Operating time before carbon exhaustion is a
function of both the flow rate and the concentration of organic compounds in the feed
stream. Treated water flows through a header and lateral collection assembly •
positioned at the bottom of the vessel and then exits the carbon filter.
Activated carbon adsorption is a surface attraction phenomenon influenced by several
factors. These include physical properties of the carbon and contaminant compounds
and system characteristics such as dissolved solids concentration, water temperature,
and pH. The combined quantitative effect of all these factors can be expressed by the
Freundlich adsorption equation, in which the amount of compound adsorbed per unit
mass of carbon is equal to a constant (K) multiplied by the final concentration of the
compound after treatment and raised to the power of another constant (n). Both K
and n, known as Freundlich parameters, are determined empirically on a
compound-specific basis. K is an approximate indicator of adsorption capacity and n
of adsorption intensity. Table 2-4 shows the Freundlich adsorption parameter K for
the contaminants of concern at hypothetical contaminant concentrations of 1.0 mg/I
and a neutral pH.
The performance of activated carbon filters depends in part on the concentration of
suspended solids in the influent stream. High concentrations of suspended solids and
oxidized iron, if not removed, will plug the carbon media and negatively affect
system hydraulics. As a result, multi-media filtration or clarification/equalization to
2-15
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SPLASH
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PRESSURE
GAUGE
.. -~,,.-
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EFFLUENT
HEADER AND
LATERALS
GRANULAR
ACTIVATED
CARBON
MEDIA
GRAVEL
SLPPORT
BED
ROCK
SUPPORT
BED
CON TAM IN A TED
WATER IN
TYPICAL ACTIVATED CARBON FILTER
-NEW HANOVER COUNTY AIRPORT BURN PIT SITE -"--'="-----------CD M FEDERAL PROGRAMS CORPORATION WILMINGTON, NORTH CAROLINA • sut:.idiuy c,fCamp 0---• Mc.x.. IDc. FIGURE No. 2·2
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TABLE 2-4
FREUNDLICH PARAMETER K VALUES FOR CONTAMINANT COMPOUNDS
NEW HANOVER COUNTY AIRPORT BURN PIT SITE
WILMINGTON, NORTH CAROLINA
Benzene 1.0 5.3
0.7 7.0
Chloroform 2.6 5.3
7.0 11
1,2-Dichloroethane 3.6 5.3
Ethylbenzene 53 7.3
Source: James W. Patterson, 1985, pp. 331-333.
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remove suspended solids may be required as pretreatment to activated carbon. In
some cases, further filtration using in-line cartridge filters may be required to remove
smaller suspended matter. The cost involved in changing out the carbon at bed
exhaustion and disposal of the spent carbon as hazardous waste are negative impacts
of using activated carbon as a process option.
Due to relatively high K values (>0.1) shown for the contaminants at the site, it is
expected that activated carbon would be an effective groundwater treatment technique.
However, due to relatively high O&M costs when compared to air stripping and
because the organic contaminants at the site would be more readily volatilized than
adsorbed, for the purposes of alternative evaluation, carbon adsorption will be
dropped in favor of air stripping for organics removal.
Ion Exchange
Ion exchange treatment uses resins to remove dissolved metals and other inorganic
compounds from aqueous streams. Contaminant ions removed from the aqueous
solution are replaced with relatively harmless ions held by the exchange resins.
Specific ion exchange and sorptive resin systems are designed on a case-by-case basis.
The ion exchange would occur in a pressurized vessel where the matrix of the ion
exchange resins react with the contaminated water. The reactions continue until the
resins and the solution (water) in which the resin is immersed all reach equilibrium;
and consequently, the resins remove the metals. Resins lose their exchange/sorptive
abilities as they become saturated, and after a period of time, they must be
regenerated. Regeneration is a process whereby a resin-specific solution is passed
through the column, exchanging one ion (such as sodium or hydrogen) for the
contaminant ion. Significant amounts of this regenerant solution must then be
disposed of, typically as a hazardous waste. This technology is applicable for the
removal of contaminants from dilute solutions. High concentrations, however, rapidly
exhaust the resins and require frequent regeneration.
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Selective ion exchange using a special exchange resin is an effective option for
chromium (Cr+6 and cr+3) removal and lead removal at the New Hanover County
Airport Burn Pit Site. Since chromium must exist in the hexavalent state for effective
removal using ion exchange, further analysis on the groundwater is necessary to
determine the ionic form of the chromium at the site. Bench-scale testing would also
be required to demonstrate its effectiveness relative to conventional chromium
reduction followed by chemical precipitation. For the purpose of alternative
evaluation, this process option is dropped from further consideration for reduction of
concentrations of lead and chromium at the site, due to its questionable effectiveness
in removing the inorganics of concern. If physical/chemical treatment is ultimately
selected for implementation at this site, it may be worthwhile to evaluate this option
in more detail during the design phase.
Chromium Reduction
Chromium occurs in aqueous systems in both the trivalent (Cr+3) and the hexavalent
(Cr+6) ionic form, with cr+6 being much less likely to form an insoluble precipitate
than cr+3• Reduction of cr+6 to cr+3, and subsequent hydroxide precipitation of the
trivalent chromium ion, is the most common method of chromium removal. The
most common technique is to lower the waste stream pH to 2.0 -3.0 with sulfuric
acid, and convert cr+6 to cr+3 with a chemical reducing agent such as sulfur dioxide,
sodium bisulfide, metabisulfite or hydrosulfite, or ferrous sulfate. The CrH is then
removed, usually by hydroxide precipitation at an elevated pH. However, effective
reduction of cr+6 to cr+3 depends on the time allowed for reduction to occur, pH of
the reaction mixture, and concentration and type of reducing agent employed. Use of
sulfuric acid to reduce pH followed by sulfur dioxide to reduce cr+6 has been
reported to achieve cr+6 reductions from an initial concentration of 900 µg/1 to a final
concentration of 10-30 µg/1 (Patterson, 1985).
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Although it is unknown whether chromium exists in the cr+6 or cr+3 state in the
groundwater at the New Hanover County Airport Bum Pit Site, this process option is
retained for application in conjunction with chemical precipitation. Bench-scale
treatability studies should be conducted prior to finalizing the process scheme.
2.2.4 DISCHARGE TECHNOLOGIES
Because the water treatment system design is dependent on the effluent criteria for the
discharge of treated groundwater from the site, several discharge alternatives were
considered. Each discharge option is discussed and evaluated below.
Discharge to Publicly Owned Treatment Work)' (P01WI
Sanitary sewers that serve the New Hanover County Airport eventually discharge to
the James A. Loughlin Northside Wastewater Treatment Plant (Northside POTW)
operated by the City of Wilmington, North Carolina. Under a city code prohibiting
discharge of wastewaters containing explosive material (including petroleum-related
compound) (Wilmington City Code Section 12-137(3)), the groundwater may need to
be treated for benzene prior to discharge to the Northside POTW, depending upon
permit conditions. The Northside POTW discharge criteria are presented in
Table 2-5. This option has been retained for further consideration.
The exact address of the POTW under consideration is as follows:
James A. Loughlin Northside Wastewater Treatment Plant
2311 North 23rd Street
Wilmington, North Carolina 28405
Contact: Mr. Jerry Nichols, Plant Manager
Telephone: [phone]
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TABLE 2-5
EFFLUENT CRITERIA FOR DISCHARGE ALTERNATIVES
NEW HANOVER COUNTY AIRPORT BURN PIT SITE
WILMINGTON, NORTH CAROLINA
Organics
Benzene
1,2-Dichloroethane
Chloroform
Ethylbenzene
Inorganics
Chromium
Lead
NOTES:
NS -No Standard
BDL -Below Detectable Limits
NS
NS
NS
NS
50
25
1
0.38
0.19
29
50
155
1 NCDNR Administrative Code Section 15 NCAC 2B.02ll(b).
2 State Drinking Water Quality Standards, 15A NCAC lSC.1500.
3 Wilmington City Code Section 12-137(3).
~1•
NS
NS
BDL
2,000
NS
4 Benzene is not permitted into the POTW; therefore, groundwater must be treated to
below the detection limit (BDL) of benzene (1 µg/1).
5 The cleanup goal for lead is based on new EPA regulations for treatment technique
action levels (TTALs), (EPA, 1991). The SDWA MCL for lead is currently
50 µg/1. However, effective December 1992, the TTAL for lead, 15 µg/1, will
become the SDWA MCL. [The TTAL is based upon the need for water at the tap
to be less than 50 µgll, and takes into account any lead pipe and other fixtures that
may contribute to lead contamination prior to leaving the tap (EPA, 1991).)
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Surface Water Discharge
Nearby surface water bodies were evaluated as potential receiving waters for the
treated effluent from the groundwater treatment system. The surface water of
primary interest is Smith Creek, located offsite, south of the New Hanover County
Airport.
Disposal of treated effluent to Smith Creek would include approximately 4,000 feet of
buried piping and a low pressure distribution system to convey treated groundwater.
National Pollutant Discharge Elimination System (NPDES) permitting would be
required for offsite discharge. Standard construction practices would be used for
installing the buried pipeline. The treated effluent would be monitored to ensure
compliance with NPDES permitting requirements. Surface water discharge criteria,
which apply to inorganic contaminants, are listed in North Carolina Administration
Code 15A NACAC 2B.0211 and are also presented in Table 2-5. Since this option is
a viable alternative for treated water disposal, surface water discharge has been
retained for further consideration.
Onsite Discharge
The onsite discharge technology retained for the New Hanover County Airport Burn
Pit Site is spray irrigation. Spray irrigation incorporates the disposal of water through
plant uptake and evaporation (evapotranspiration) and percolation through the soil.
The hydraulic loading is limited by the infiltration capacity of the soil. Major factors
for site selection include: the type of soil, the depth to groundwater, groundwater
control and movement, and distance from the source. In addition, the efficiency of
soil infiltration would decrease under freezing conditions. As a result, an alternate
disposal or storage technology (i.e., storage tanks) would be required. The
groundwater discharge criteria that apply to both organics and inorganics present at
the New Hanover County Airport Burn Pit Site are also presented in Table 2-5.
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Since land is available at the site for spray irrigation, which can be implemented
through standard engineering methods, this discharge process option has been retained
for further consideration.
2.3 SUMMARY OF PROCESS OPTIONS EVALUATION
Based on the evaluation of the retained process options, groundwater would be
contained by a slurry wall or extracted using recovery wells. The extracted
groundwater would be pumped through a groundwater treatment system, which may
vary depending on the discharge alternative selected. The discharge options for
treated groundwater include: onsite spray irrigation, discharge to the City of
Wilmington Northside POTW, or discharge to Smith Creek. The evaluation of the
process options is summarized in Table 2-6.
2.4 DEVELOPMENT OF REMEDIAL ACTION ALTERNATIVES
In combining groundwater containment, collection, treatment, and disposal process
options to develop remedial action alternatives, all technologies feasible for the New
Hanover County Airport Burn Pit Site were considered. As previously discussed,
where more than one process option is appropriate within a given technology group,
one option or combination of options is used in the development of alternatives for
ease in evaluation. Further, more detailed, evaluation of specific processes should be
conducted after remedy selection (remedial design phase). The following are the
sitewide alternatives developed for the site.
Alternative 1 -No Action
Alternative 2 -Vertical Barrier
Alternative 3 -Groundwater Extraction and Physical Treatment (Air Stripping) with
Discharge to POTW
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TABLE2-6
EVALUATION OF PROCESS OPTIONS
NEW HANOVER COUNTY AIRPORT BURN PIT SITE
WILMINGTON, NORTH CAROLINA Groundwater General
Response Actions Remedial Technology Process Option Effectiveness
~I N_o_A_c_tio_n __ ~H~~-o_ne ____ _!"--;_I _N_ot_app_li_cab_le ____ ---'
Institutional
actions
Containment
Access restrictions
Monitoring
e---1 Vertical barriers
t------1 Deed restrictions
1------. Groundwater monitoring
Slurry wall
Does not achieve remedial action objectives
Effectiveness depends on continued future
implementation. Does not reduce contamination.
Useful for documenting conditions. Does not
reduces risk by itself.
Effective, but susceptible to weathering. Capping
required to prevent mounding.
Effective if proprietary fixation chemicals are
used to ensure lmpenneable banier. capping
required to prevent mounding.
Implementability
Not acceptable to locaVpublic
govemmenl
Legal requirements and authorily
Aiona, not acceptable to public/local
govemmenl
Cost
None
Negligible cost
Low capital, low O&M
Readily implementable, adequate salely High capital, low
measures required when digging trench maintenance.
Appropriate fixation chemicals Very high capital, low
would be required. Treatabilitiy maintenance.
tests may be required.
Effective, least susceptible to cracking. Capping Readily implementable Very high capital, low
maintenance.
CoUectlon
Treatment
Discharge
Extraction
1---~ PhysicaYchemical
treatment
Onsite discharge
Olfsite discharge
Precipitation
Air stripping
e-----. Spray irrigation
POTW
Pipeline to surface water
::::::::::::::/::! Process option eliminated from further consideration ~-------~
required to prevent mounding.
Effective and reliable; conventional technology
Effective and reliable; conventional technology.
Requires sludge disposal.
Effective and reliable; Proper pretreatment
required.
Effective and reliable; Proper pretreatment
required. Requires disposal of used carbon.
Effective and reliable
Effective and reliable; Prope,r monitoring required.
Effective and reliable; Effluent needs to meet
required discharge limits.
Effective and reliable; Effluent needs to meet
required discharge limits.
Effective and reliable; Effluent needs to meet
required discharge limits.
Readily implementable
Readily implementable
Readily Implementable
Readily implementable
Readily implementable
Penni! required; must provide storage
during cold and wet weather.
Further negotiations may be required
to ensure acceptance of treated water
by POTW
Pennit required
Pennit required
Low capital, moderate O&M
High capital,
highO&M
Low capital,
lowO&M
High capital, high O&M
High capital, moderate O&M
Moderate capital,
moderate O&M
Moderate capital,
moderate O&M
Low capital,
lowO&M
Moderate capital,
lowO&M
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Alternative 4 -Groundwater Extraction and Physical/Chemical Treatment (Chromium
Reduction, Metals Precipitation, and Air Stripping) with Discharge
via Spray Irrigation
Alternative 5 -Groundwater Extraction and Physical/Chemical Treatment (Chromium
Reduction and Metals Precipitation) with Discharge to Surface Water
These alternatives are discussed further in Section 3.0.
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3.0 EVALUATION OF REMEDIAL ACTION ALTERNATIVES
In this section, a description and evaluation of each remedial action alternative is
provided. The evaluation of alternatives generally involves developing a conceptual
design for the corrective action and identifying key factors relating to the remediation.
This section describes five remedial action alternatives for the New Hanover County
Airport Burn Pit Site. In accordance with the NCP, these alternatives were evaluated
based on the following factors:
• Overall protectiveness
• Compliance with ARARs
• Long-term effectiveness and permanence
• Reduction of mobility/toxicity/volume (M/T/V)
• Short-term effectiveness
• Implementability
• Cost
First, by using the overall protectiveness criterion, each alternative was assessed to
determine its ability to adequately protect human health and the environment (both
short-and long-term) from unacceptable risks posed by the groundwater contaminants
present at the site. Second, the alternative was assessed to determine whether its
compliance with ARARs under federal, state, and local environmental laws applicable
to this specific site. Third, the alternative was also evaluated for the long-term
effectiveness and permanence it affords, along with the degree of certainty that the
alternative will prove successful. Fourth, the degree to which the alternative reduces
toxicity, mobility, and volume was assessed. Fifth, the short-term impact of the
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alternative was assessed. Sixth, the ease or difficulty of implementing the alternative
was assessed. Finally, the capital, annual operation and maintenance (O&M) costs,
and net present value of capital and O&M costs were evaluated.
3.1 GROUNDWATER EXTRACTION ANALYSIS
In order to identify operating criteria for the long-term corrective action alternatives
involving groundwater extraction, FPC developed a groundwater model for the New
Hanover County Airport Burn Pit Site to simulate an extraction scenario using
extraction wells. The results of the groundwater extraction analysis are presented as
the first component in the evaluation of corrective action alternatives.
FPC developed a two-dimensional groundwater flow model for conditions at the site
to help estimate the duration of pumping required to capture the dissolved
contaminant plume. The flow model was also developed to predict the impact of
pumping on local groundwater levels. FPC selected the model for this analysis based
on the Theis groundwater flow equation (Theis, 1935). This analytical equation
describes transient flow to a well pumping from a homogeneous, isotropic aquifer of
uniform thickness and infinite extent, where wells are screened throughout the depth
of the aquifer and have an infinitesimally small diameter. Simulated water level
drawdown contours were performed by superimposing the field-measured regional
hydraulic gradient to determine the resultant hydraulic gradient at the site. Based on
the resultant hydraulic gradient and Darcy's Law for calculating groundwater flow
velocities, approximate durations of extraction required to capture the contaminant
area were calculated. Generally, this method applies only to flow in confined
aquifers, but the error involved in applying it to unconfined situations, such as the
New Hanover County Airport Burn Pit Site, is small (EPA, 1989).
Several assumptions were made to simulate groundwater extraction at the site.
Sufficient monitoring should be performed during the design, installation, and
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operation of the final extraction system to confirm these assumptions and fully assess
the effectiveness of the extraction system. Existing wells and piezometers are not
adequate to fully define the extent of contamination. The installation of new monitor
wells and piezometers will be necessary to adequately monitor the effects of the
groundwater recovery system on groundwater quality and drawdown of the aquifer.
3.1.1 AQUIFER CHARACTERISTICS
For the purposes of groundwater modeling, an average storativity of 6.3 x 10·3
(unitless) and effective porosity of twenty percent were assumed to sufficiently
represent the hydrogeologic conditions at the site. In addition, a static head of 28 feet
of water column is used as a representative value for the average static head
conditions within the area modeled. The average hydraulic gradient is assumed to be
relatively flat based on the inconsistent and relatively small variations in water level
measurements presented in EPA's remedial investigation report, and the fact that
water level elevations tend to follow surface topography, which is relatively flat
within the New Hanover County Airport Bum Pit Site. A hydraulic conductivity of
6.6 ft/day and a transmissivity of 146 ft2/day are assumed to be representative of the
saturated thickness of the unconfined aquifer (EPA, 1992b).
3.1.2 GROUNDWATER MODELING ASSUMPTIONS
In order to model the groundwater conditions at the site, the following assumptions
were made.
1. Estimates of the duration of pumping required to capture the area of
contamination assumes only advective transport. Properties such as
sorption, retardation, dispersion, and biodegradation are not modeled.
2. Groundwater flow during continuous pumping conditions is assumed to
be steady-state.
3-3
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3.1.3
3.
4.
5.
The aquifer is assumed to be homogeneous and isotropic.
The extraction wells are assumed to be screened throughout the depth
of the aquifer and have an infinitesimally small diameter.
The source of groundwater contamination is assumed to be removed or
non-existent.
THEIS ANALYSIS RESULTS
The principal means of optimizing contaminated groundwater recovery is through the
alteration of the water gradient to enhance and/or control contaminant movement.
This can be accomplished by placing an extraction system downgradient of the
contaminant area, inducing a water gradient, or artificially influencing an existing one
via groundwater extraction.
Three groundwater extraction wells, placed downgradient within the contaminant
plume (see Section 1.5.1) to contain the plume and prevent further migration of
contaminated groundwater offsite, were evaluated. The groundwater extraction wells,
depicted in Figure 3-1 as EX-1, EX-2, and EX-3, are approximately 120 feet apart,
overlapping the cones of influence to ensure complete capture of the contaminant
plume. A production rate of 5 gpm per well (15 gpm total) for the three extraction
wells was assumed based on the Theis analysis and results from the aquifer test
presented in EPA's remedial investigation. Although actual flow rates are not
expected to vary significantly from those assumed, exact capacities should be
determined in the field during installation of the extraction wells.
Referring to Figure 3-1, the scenario presented above was simulated for steady-state
conditions at the 15 gpm total pumping rate, and the resulting hydraulic gradient
shows capture of the contaminant plume. However, due to the tendency for
petroleum hydrocarbons to adsorb to soil particles, extraction of several pore volumes
of contaminated groundwater is often required for adequate capture of the dissolved
3-4
NHANFS09 .002
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LEGEND
rrn,1111,,,,,,,,,,,
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BERM/ROAD
EXCAVATION
POS98LE SURFACE WATER
DRAINAGE AREAS
SIMULATED
EXTRACTION WELL
,,,,-21 _,,,. DRAWDOWN CONTOUR
(Feet)
ARMY CORPS
OF ENGINEERS
UST FARM
,
II
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---------~:::.::::--
. ,,
'
/
TO WILMINGTON
APPROXIMATE TOTAL
EXTENT OF CONTAMINATION
IN GROUNDWATER
<,'<-~
,,,,J <l,<:j
~ ~ -N-~
100 0 100
APPROXIMATE
SCALE IN FEET
EXTRACTION WELL DRAWDOWN AT STEADY STATE -15 GPM
NEW HANOVER COUNTY AIRPORT BURN PIT SITE
[
~ ~
"' ~ ~
200
CDM FEDERAL PROGRAMS CORPORATION
•~ofCmq,l>Raer-.t. Mdtce Inc. WILMINGTON, NORTH CAROLINA FIGURE No. 3-1
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constituents. As a result, this can increase the duration of cleanup required by a
factor of three or more. The reduction of contaminant concentrations over time is the
primary indicator of the effectiveness of an extraction system. The ideal scenario
would be a steady decrease in contaminant concentrations until a target level is
attained. However, performance records suggest that although concentrations may
drop initially, decline is followed by a leveling of concentrations with little or no
further decrease over time (EPA, 1989). The number of estimated pore volumes
required to capture the estimated 9,694,080 gallons of contaminated groundwater can
be approximated based on cleanup goals for the site. Generally, it is assumed that
three to five pore volumes may flush the site of dissolved contamination.
Based on the aquifer and contaminant characteristics and Darcy's Law for calculating
flow rates, the estimated duration to capture three pore volumes of the contaminant
plume at a pumping rate of 15 gpm is estimated to be 4 years. However, this is only
an approximation and could be predicted more accurately at the design stage through
field tests (i.e., grain size, total organic content, and pump tests).
3.2 ALTERNATIVE 1 -NO ACTION
3.2.1 DESCRIPTION
This alternative provides the baseline case for comparing remedial actions and the
level of improvement achieved. This alternative consists of leaving the site as it is
without conducting any further remedial actions. However, long-term groundwater
monitoring of six monitor wells, including three proposed wells on the northern,
western, and eastern edges of the plume, would be conducted to track changes in
environmental quality over an estimated 30-year period.
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3.2.2 EVALUATION
Overall Protectiveness
The no-action alternative does not eliminate any exposure pathways or reduce the
level of risk.' The risk assessment concludes that existing contamination would result
in an excess lifetime cancer risk exceeding 10--6 for groundwater at the site.
Compliance with ARARs
This alternative does not achieve the remedial action objectives or ARARs established
for the site.
Long-Term Effectiveness and Permanence
The continued contaminant migration via groundwater transport to potential offsite
receptors is a long-term impact of this alternative.
Reduction of M/T/V
No reductions in contaminant M/T/V are realized and groundwater cleanup goals
would be exceeded. The no-action alternative, therefore, is not considered to be
protective of human health and the environment.
Short-Term Effectiveness
Since no further remedial actions would be implemented at the site, this alternative
poses no short-term risks to onsite workers. It is assumed that Level D personal
protection would be used when sampling the existing wells for groundwater
monitoring purposes.
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Implementability
This alternative could be implemented immediately.
Cost
The estimated annual operation and maintenance (O&M) cost for this alternative is
approximately $7,920. The present net worth O&M costs for this alternative is
approximately $74,661, a discount rate of 10 percent over 30 years. Detailed cost
estimates are presented in Appendix C.
3.3 ALTERNATIVE 2 -VERTICAL BARRIER
3.3.1 DESCRIPTION
This alternative involves containing the groundwater plume with a vertical barrier
(i.e, slurry wall) and constructing an impermeable cap to prevent groundwater
mounding. When using a slurry wall, a trench would be excavated around the
approximate extent of contamination shown in Figure 1-13. The trench would extend
over a length of approximately 1,600 feet and a depth of at least 30 feet bis and
should be anchored to the confining layer. After excavation, the trench can be
backfilled with a mixture of cement-bentonite to create an impermeable vertical
barrier that would prevent potential migration of the plume. Some dewatering may be
required during implementation of this technology. For ease in implementation and to
minimize worker exposure risks, the excavation would be performed in phases. This
technology would have to be used in conjunction with capping of the site to prevent
any mounding that could occur due to the rainfall infiltration that would be captured
by the vertical barrier. A cross-section of the cap is shown on Figure 3-2.
3-8
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2% MINIMUM SLOPE
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'v /VVVVVV.' ,,, '' "' "' "' "~VVVVVVV / · f V v V V v V -c;~ACJED.SOlL C\)VE!:l• V v V V V V V '-V VVVVVVVVVVVVVVVVVVVV / vvvvvvvvvvvvvvvvvvvv, V VVVVVVVVVVVVVVVVVVVV / vvvvvvvvvvvvvvvvvvvv,
. ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' . ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' '
40 MIL HDPE
SYNTHETIC LINER
GEOTEXTILE
{8 Ounces)
CROSS-SECTION OF TYPICAL IMPERMEABLE SURFACE CAP
-NEW HANOVER COUNTY AIRPORT BURN PIT SITE =-"'-=--------------CD M FEDERAL PROGRAMS CORPORATION WILMINGTON, NORTH CAROLINA
llllbaidla:ry of(:ai:i:ip ~& McJCoo loc. FIGURE No. 3·2
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Capping would prevent infiltration and applicable drainage structures (i.e., ditches and
retention basins) may be required to redirect surface runoff. The cap would be
installed over the approximate extent of contamination (shown in Figure 1-13), which
extends over an approximate area of 3.5 acres. An impermeable cap typically
consists of four layers. A minimum of 6 to 12 inches of cover material would be
placed over the existing soils to provide a foundation to support the cap. An
impermeable membrane (i.e., 40 mil HDPE liner) would be placed over the cover
material and would be underlain by a protective geotextile fabric to protect it from
puncture. A I-foot drainage layer above the liner would be constructed of sand. The
top foot of the cap would consist of topsoil to provide a root wne for vegetative
growth to prevent erosion. The cap would have a minimum slope of 2 percent.
Surface runoff would be directed through appropriate drainage channels. Precipitation
that percolates through the topsoil would flow laterally through the sand drainage
layer and into the drainage channels.
3.3.2 EVALUATION
Overall Protectiveness
The contaminated groundwater would be contained, therefore minimizing the risk of
contaminating downgradient drinking water wells. This alternative greatly reduces the
risk of groundwater ingestion and inhalation during showering for potential receptors.
Compliance with ARARs
Containment of the plume would be achieved. Groundwater contaminant
concentrations, however, would not meet the established cleanup goals for the New
Hanover County Airport Bum Pit Site.
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Long-Term Effectiveness and Permanence
The potential for long-term migration of the contaminant plume would be greatly
reduced. Although weathering of the slurry wall may occur, slurry walls are typically
expected to have a serviceable life of at least 30 years. Installation of an
impermeable cap would result in increased runoff, which could cause offsite erosion.
Although liners are typically warranted for 20 years, the serviceable life could well
extend beyond this timeframe. Restrictions on future land use would be required.
This remedy is not considered permanent.
Reduction of M/T/V
No reductions in contaminant toxicity or volume are realized and groundwater cleanup
goals would be exceeded. However, the mobility of the groundwater contamination
would be greatly reduced.
Short-Term Effectiveness
Adequate shoring mechanisms (i.e., sloping and use of retaining walls) should be
considered when excavating the trenches to minimize risks to workers. Construction
activities at the site could result in the release of toxic gas emissions from the
contaminated groundwater. Also, operation of heavy equipment during construction
would produce some noise nuisance. It is assumed that Level D personal protection
would be used during construction activities.
Equipment and personnel decontamination facilities would also be necessary. A
heavy equipment washdown pad would be constructed and trench excavation
equipment, if in contact with contaminated groundwater, would be decontaminated
prior to leaving the site. Washwater would be stored in drums and removed for
offsite treatment.
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Implementability
Preliminary Schedule
Approximately six months would be required for design and contractor selection.
Construction of the vertical barrier would require approximately six months.
Construction of the surface cap would require approximately two months. Assuming
no major delays, this alternative could be implemented in approximately 1.5 years.
Installation of three monitor wells to better determine the total extent of contamination
along the northern, western, and eastern edges of the plume.
Engineering Considerations for Vertical Barrier
The major engineering considerations for the implementation of a slurry wall are:
• Selection of slurry materials to be compatible with groundwater
contaminants
• Design and installation of offsite downgradient monitor wells
• Design and determination of barrier depth
• Design and construction of subsurface drains for dewatering purposes
Engineering Considerations for Impermeable Cap
The major engineering considerations for the implementation of the cap are:
• Anticipated serviceable life of the liner
• Liner permeability, tensile strength, resistance to shrinkage, punctures
and tears, handling, and seaming
• Cap thickness and infiltration potential
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• Capping materials
• Design and construction of a stormwater runoff collection system
• Environmental factors, including temperature, rainfall, wind, and
sunlight
• Design and construction of subsurface drains
Equipment and Materials
The major construction equipment and materials required for implementing this
alternative include:
• Contractor's temporary facilities and utilities
• Soil cover
• Synthetic liner materials
• Bulldozer
• Backhoe
• Front-end loader
• Dump trucks
• Hydroseeding equipment
• Cement and bentonite for slurry wall
• Water source for barrier construction
Operation and Maintenance
Short-and long-term monitoring would be required for this alternative. Air
monitoring during trench excavation activities would be necessary to ensure that a
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safe working environment is maintained and that no threat to the public health or the
environment is created by the volatilization of groundwater contaminants at the site.
For costing purposes, it was assumed that four new downgradient monitor wells
would be sampled annually for 30 years. Samples would be analyzed for benzene,
chloroform, 1,2-dichloroethane, chromium, ethylbenzene, and lead.
The total present net worth cost for this alternative is approximately $1,087,652,
including capital costs of $925,887 and present worth O&M costs of $161,766, using
a discount rate of 10 percent over 30 years. The estimated annual O&M cost for this
alternative is approximately $17,160. Detailed cost estimates are presented in
Appendix C.
3.4 ALTERNATIVE 3 -GROUNDWATER EXTRACTION
AND PHYSICAL TREATMENT (AIR STRIPPING}
WITH DISCHARGE TO POTW
This alternative includes groundwater extraction, VOC removal using air stripping,
and discharge to the Northside POTW, owned by the City of Wilmington. A detailed
description of the remediation to be conducted under this alternative is provided
below.
3.4.1 DESCRIPTION
Groundwater would be extracted as described in Section 3 .1. The estimated locations
of groundwater extraction collectors are represented in Figure 3-1. Groundwater
would be extracted from extraction wells located within the dissolved plume.
Groundwater would be pumped directly to the onsite treatment system. Groundwater
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recovery would be accomplished at an approximate steady-state rate of 15 gpm.
Groundwater remediation is estimated to take approximately 4 years.
As previously discussed, groundwater contaminants to be removed from the site are
benzene, chloroform, 1,2-dichloroethane, chromium, ethylbenzene, and lead. After
extracting the contaminated groundwater exceeding cleanup goals, benzene and
ethylbenzene would be treated onsite by air stripping to meet the "below detection
limit" (i.e., 1.0 µg/1 for benzene) requirement for ultimate discharge to the POTW.
Existing chloroform and 1,2-dichloroethane concentrations would also be significantly
reduced through air stripping. Treated groundwater would flow from the air stripper
to a sewer connection to the POTW. Sewer lines exist along the perimeter roads of
the New Hanover County Airport. Pretreatment equipment such as green sand filters
may be required to remove TSS and iron prior to air stripping. For costing purposes,
the use of a pretreatment system is assumed to avoid the potential fouling of the air
stripper.
The groundwater treatment system would be designed to operate 24 hours per day.
System controls would allow for complete automatic operation with minimal operator
attention. Alarms and switches would be furnished as required for fail-safe operation.
Instruments to monitor key operating parameters, such as water flow rate, system line
pressure, and multi-media filter differential pressure, would be included.
For costing purposes, it is assumed that all treatment equipment would be leased. To
the extent possible, major equipment would be furnished skid-mounted and complete
with all piping and controls mounted on structural steel support skids. Due to low
VOC concentrations in the groundwater it is assumed that air quality standards may
not be exceeded; therefore, no air quality control equipment would be required to •
capture residual VOCs released from the air stripper.
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3.4.2 EVALUATION
Overall Protectiveness
The greatest reduction in the potential risk of groundwater ingestion and inhalation
would be achieved since all contaminated groundwater would be extracted, and treated
to levels acceptable for POTW discharge.
Compliance with ARARs
Groundwater contaminant concentrations would meet the established cleanup goals for
the New Hanover County Airport Burn Pit Site. The treated effluent would meet the
POTW requirements.
Long-Term Effectiveness and Permanence
The potential of offsite contaminant migration via groundwater would be eliminated
permanently. The groundwater treatment system would require performance
specifications to ensure the adequate operation of the system. Long-term public
health risks associated with groundwater ingestion and inhalation would be eliminated.
No future site use restrictions would be required once groundwater extraction
treatment is completed.
Reduction of M/T/V
Extraction and treatment of contaminated groundwater would achieve a maximum and
permanent reduction of contaminant mobility, toxicity, and volume in the
groundwater.
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Short-Tenn Effectiveness
Small-scale construction activities during installation of the extraction wells and
during air stripper operation may result in the release of minimal volatilized
contaminants, and the operation of drilling equipment would produce additional noise.
Therefore, health and safety requirements while implementing this alternative would
include periodic monitoring of organic vapors and the use of personal protection
equipment by all personnel at the site. It is assumed that Level D personal protection
would be used. Equipment and personnel decontamination facilities would also be
necessary.
Implementability
Preliminary Schedule
Approximately six months would be required for design and contractor selection.
Groundwater extraction and remediation would require approximately 4 years.
Assuming no major delays, this alternative could be implemented in approximately
4.5 years.
Engineering Considerations for Groundwater Extraction and Discharge
The major engineering considerations to implement the groundwater extraction and
discharge systems include:
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Design, installation, and testing of extraction well system
Potential for well plugging (reduction in flows) over time
Monitoring requirements including the installation of three new monitor
wells, one located on the northern, western, and eastern edges of the
plume
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Difficulty in capturing residual contaminant concentrations
Cleanup verification
Well abandonment
Piping of treated effluent to sewer line connected to POTW
• Permit requirements for the Northside POTW and ability to obtain a
discharge permit
Engineering Considerations for Groundwater Treatment
The major engineering considerations to implement the groundwater treatment system
include:
• The need to implement pretreatment equipment
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Siting and design of pretreatment units (if required) and air stripper
Monitoring the effluent water quality for POTW discharge
The need to implement treatment equipment for off-gases from the air
stripper and monitoring the effluent air quality from the air stripper
• Process effectiveness monitoring
• Potential for fouling of media
Equipment and Materials
The major system components required for operations under this alternative include:
•
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Submersible groundwater pumps
Air stripping tower (with packing) for the groundwater treatment
system and only pretreatment equipment required
Piping, fittings, and valves for fluids transport
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• Electrical conduit and wiring for electric power and sensors
• System instrumentation and controls
The major construction equipment and materials required to implement this alternative
include:
• Contractor's temporary facilities and utilities
• Well drilling equipment
• Front-end loader
• Backhoe
Operation and Maintenance
Long-term groundwater monitoring for cleanup verification purposes would be
required for this alternative. It is assumed that six wells would be sampled (including
new wells) and water levels recorded on a quarterly basis for the first 4 years
(assuming 4 years for plume capture) and on an annual basis for the following 26
Yeat;S.• Samples would be collected and analyzed for benzene, chloroform,
1,2-dichloroethane, chromium, ethylbenzene, and lead.
The groundwater treatment system would also require monitoring and maintenance
during its approximate 4-year operational life. Monitoring of the treatment system
would include periodic sampling of the influent and effluent from the treatment
system and analyzed in accordance with the POTW discharge permit requirements.
Sample collection is assumed to be on a weekly basis. Samples are anticipated to be
analyzed for benzene, ethylbenzene, and pH, and any other parameters required by
the Northside POTW discharge permit.
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Maintenance of the extraction and treatment systems would be performed in
accordance with O&M requirements developed after equipment specification and
procurement are completed. At a minimum, it is expected that regular periodic
maintenance would be required on the submersible pumps, valves, and fittings of
fluids piping systems, as well as on the treatment system components (i.e., tower
packing media cleaning and/or replacement) to ensure the efficient operation of the
system.
The total present net worth cost for this alternative is approximately $1,879,801,
including capital costs of $805,617 and present worth O&M costs of $1,074,184,
using a discount rate of 10 percent over 30 years. The estimated annual O&M cost
for this alternative is approximately $315,985 for the first 4 years and $7,920 for the
remaining 26 years. Detailed cost estimates are presented in Appendix C.
3.5 ALTERNATIVE 4 -GROUNDWATER EXTRACTION AND
PHYSICAL/CHEMICAL TREATMENT (CHROMIUM
REDUCTION. METALS PRECIPITATION. AND AIR STRIPPING}
WITH DISCHARGE VIA SPRAY IRRIGATION
This alternative includes groundwater extraction, chromium reduction, metals
precipitation, air stripping, and onsite discharge by spray irrigation. A detailed
description of the remediation to be conducted under this alternative is provided
below.
3.5.1 DESCRIPTION
Groundwater would be extracted as described in Section 3 .1. The locations of
groundwater extraction collectors are represented in Figure 3-1. Groundwater would
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be extracted from extraction wells located within the dissolved plume. Groundwater
would be pumped directly to the onsite treatment system. Groundwater recovery
would be accomplished at an approximate steady-state rate of 15 gpm. Groundwater
remediation is estimated to require approximately 4 years.
As previously discussed, groundwater contaminants to be removed from the site are
benzene, chloroform, 1,2-dichloroethane, chromium, ethylbenzene, and lead. After
extracting the contaminated groundwater exceeding cleanup goals, the groundwater
would be treated onsite by chromium reduction, metals precipitation, and air stripping
to meet state requirements for ultimate groundwater discharge via spray irrigation.
To meet these requirements, concentrations of all six site contaminants must be
reduced. Treated groundwater would be pumped from the metals precipitation system
into the air stripper and finally to a pipeline with sprinklers to be spray irrigated
onsite.
For evaluation purposes, it is assumed that this alternative would consist of chromium
reduction, metals precipitation using sodium hydroxide, flocculation, clarification, and
filtration. Flocculation and clarification are necessary to enhance solids removal,
reducing the load on filtration, and minimizing filter backwashing frequency. The
treatment scheme involves pumping the contaminated groundwater into a series of
mixing tanks where it is rapidly combined with chemicals for pH adjustment,
chromium reduction, precipitation, and flocculation. Following the mixing stage, the
water flows into a clarifier, where the solids-liquid separation occurs. Due to the low
effluent limits for metals, it is expected that sand or multi-media filtration will be
required to remove residual solids after settling.
The settled sludge is then pumped to a storage tank for subsequent dewatering using a
filter press. The water recovered from the dewatering operation would be recycled to
the treatment's influent stream, and the concentrated sludge/filter cake analyzed and
disposed offsite at a hazardous or solid waste landfill, as applicable. The treated
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effluent from the filter would be discharged to the air stripper to remove voes of
concern. All metal and organic concentrations would be reduced to below state
groundwater discharge permit requirements. The treated groundwater would then be
pumped to an onsite spray irrigation system. Operation of the extraction system
during wet weather or freezing temperature conditions requires provisions for
sufficient storage of treated groundwater, anticipating an appropriate design rainfall.
A variation to this treatment scheme should be considered during the design phase.
Although hexavalent chromium can be reduced in a pretreatment step prior to
precipitation, it can also be removed as cr+6 by an ion exchange column after the
filtration step has effectively removed other metal hydroxide solids.
The groundwater treatment system would be designed to operate 24 hours per day.
System controls would allow for complete automatic operation with minimal operator
attention. Alarms and switches would be furnished as required for fail-safe operation.
Instruments to monitor key operating parameters, such as water flow rate, system line
pressure, and multi-media filter differential pressure, would be included.
For costing purposes, it is assumed that all treatment equipment would be leased. To
the extent possible, major equipment would be furnished skid-mounted and complete
with all piping and controls mounted on structural steel support skids. It is assumed
that no air quality control equipment would be needed to capture voes released from
the air stripper, due to their low concentrations in the groundwater.
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3.5.2 EVALUATION
Overall Protectiveness
The greatest reduction in the potential risk of groundwater ingestion and inhalation
would be achieved since all contaminated groundwater would be extracted and treated
to levels acceptable for onsite groundwater discharge.
Compliance with ARARs
Groundwater contaminant concentrations would meet the established cleanup goals for
the New Hanover County Airport Bum Pit Site. The treated effluent would meet
state groundwater discharge permit requirements. Spray irrigation would meet all
substantive requirements for state permitting of spray irrigation fields.
Long-Term Effectiveness and Permanence
The potential for offsite contaminant migration via groundwater would be eliminated
permanently. The groundwater treatment system would require performance
specifications to ensure the adequate operation of the system. Long-term public
health risks associated with groundwater ingestion and inhalation would be eliminated.
No future site use restrictions would be required once groundwater extraction and
treatment are complete.
Reduction of M/T/V
Extraction and treatment of contaminated groundwater would achieve a maximum and
permanent reduction of contaminant mobility, toxicity, and volume in the
ground water.
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Short-Term Effectiveness
Small-scale construction activities during installation of the extraction wells and
during air stripper and mixing equipment operation may result in the release of
minimal volatilized contaminants, and the operation of drilling equipment would
produce additional noise. Therefore, health and safety requirements while
implementing this alternative would include periodic monitoring of organic vapors and
the use of personal protection equipment by all personnel at the site. It is assumed
that Level D personal protection would be used. Equipment and personnel
decontamination facilities would also be necessary.
Implementability
Preliminary Schedule
Approximately six months would be required for design and contractor selection.
Groundwater extraction and remediation would require approximately 4 years.
Assuming no major delays, this alternative could be implemented in approximately
4.5 years.
Engineering Considerations for Groundwater Extraction and Discharge
The major engineering considerations to implement the groundwater extraction and
discharge systems include:
• Design, installation, and testing of extraction well system
• Potential for well plugging (reduction in flow) over time
• Monitoring requirements
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Cleanup verification including the installation of three monitor wells on
the northern, western, and eastern edges of the plume
Well abandonment
Spray irrigation system
• Permit requirements for the onsite groundwater discharge
Engineering Considerations for Groundwater Treatment
The major engineering considerations to implement the groundwater treatment system
include:
• Siting and design of metals removal system and air stripper
• Volume of sludge generated from metals precipitation
•
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Monitoring the effluent water quality for groundwater discharge
Monitoring the sludge/filter cake generation from the metals removal
system
Determining the need for treatment of off-gases and monitoring the
effluent air quality from the air stripper
Ease in treatment system operation
Determining if system-generated waste materials are hazardous wastes
under RCRA
Process effectiveness monitoring
Potential for fouling of stripper media
Provision for chemical storage
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Equipment and Materials
The major system components required for operations under this alternative include:
• Submersible groundwater pumps
• Tankage, mixers, controls associated with metals removal system
• Sodium hydroxide, sulfuric acid, required flocculants and coagulants,
and other treatment chemicals
• Air stripping tower
• Pumps, piping, fittings, and valves for fluids transport
• Electrical conduit and wiring for electric power and sensors
• Instrumentation and controls
• Spray irrigation system
The major construction equipment and materials required to implement this alternative
include:
• Contractor's temporary facilities and utilities
• Front-end loader
• Backhoe
Operation and Maintenance
Long-term groundwater monitoring for cleanup verification purposes would be
required for this alternative. It is assumed that six wells would be sampled (including
two new wells) and water levels recorded on a quarterly basis for the first 4 years
(assuming 4 years for plume capture) and on an annual basis for the following
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26 years. Samples would be collected and analyzed for benzene, chloroform,
1,2-dichloroethane, chromium, ethylbenzene, and lead .
The groundwater treatment system would also require monitoring and maintenance
during its approximate 4 year operational life. Monitoring of the treatment system
would include normal troubleshooting and periodic water sampling of the influent,
midpoint, and effluent from the treatment system and analysis in accordance with the
groundwater discharge permit requirements. Collection of samples is assumed to be
on a weekly basis. Samples are anticipated to be analyzed for benzene, chloroform,
1,2-dichloroethane, chromium, ethylbenzene, lead, pH, and any other parameters
required by state groundwater discharge permit. In addition, any sludge generated
would have to be packaged and disposed offsite at a hazardous or solid waste landfill,
as applicable. Finally, downgradient groundwater monitoring would be required to
ensure that the permit conditions are met, including groundwater table level
requirements.
Maintenance of the extraction and treatment systems would be performed in
accordance with O&M requirements developed after equipment specification and
procurement are completed. At a minimum, it is expected that regular periodic
maintenance would be required on the pumps, valves, and fittings of fluids piping
systems, as wells as on the treatment system components (i.e., cleaning of pH probes,
filter backwashing, replacement of consumable items, and sludge generation) to
ensure the efficient operation of the system.
The total present net worth cost for this alternative is approximately $2,319,154,
including capital costs of $1,053,938, and present worth O&M costs of $1,265,217,
using a discount rate of 10 percent over 30 years. The estimated annual O&M cost
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for this alternative is approximately $376,250 for the first four years and $7,920 for
the remaining 26 years. Detailed cost estimates are presented in Appendix C.
3.6 ALTERNATIVE 5 -GROUNDWATER EXTRACTION AND
PHYSICAL/CHEMICAL TREATMENT <CHROMIUM REDUCTION
AND METALS PRECIPITATION) WITH DISCHARGE
TO SURFACE WATER
This alternative includes groundwater extraction, metals precipitation, and discharge
to Smith Creek located approximately 4,000 feet south of the site. A detailed
description of the remediation to be conducted under this alternative is provided
below.
3.6.1 DESCRIPTION
Groundwater would be extracted as described in Section 3.1. The locations of
groundwater extraction collectors are represented in Figure 3-1. Groundwater would
be extracted from extraction wells located with the dissolved plume. Groundwater
would be pumped directly to the onsite treatment system. Groundwater recovery
would be accomplished at an approximate steady-state rate of 15 gpm. Groundwater
remediation is estimated to require approximately 4 years.
As previously discussed, groundwater contaminants to be removed from the site are
benzene, chloroform, 1,2-dichloroethane, chromium, ethylbenzene, and lead. After
extraction of the contaminated groundwater exceeding cleanup goals, the groundwater
would be treated onsite by chromium reduction and metals precipitation to meet the
State of North Carolina requirements for ultimate surface water discharge. Treated
groundwater would flow from the treatment system to a pipeline that follows Gardner
Street into 23rd Street and eventually discharging into Smith Creek.
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The primary objective of treatment would be reduction of chromium concentrations.
The treatment portion of this alternative would consist of chromium reduction metals
precipitation using sodium hydroxide, flocculation, clarification, and filtration.
Flocculation and clarification are necessary to enhance metal removal, reducing the
load on filtration, and minimizing backwashing. The treatment scheme involves
pumping the contaminated groundwater into a series of mixing tanks where it is
rapidly combined with chemicals for pH adjustment, chromium reduction,
precipitation, and flocculation. Following the mixing stage, the water flows into a
clarifier, where the solids-liquid separation occurs.
The settled sludge is then pumped to a storage tank for subsequent dewatering using a
filter press. The water recovered from the dewatering operation is returned to the
treatment's influent stream, and the concentrated sludge/filter cake is analyzed and
disposed offsite at a hazardous or solid waste landfill, as applicable. All metal
concentrations would be removed to below the state surface water discharge permit
requirements. The treated groundwater would flow from the treatment system to a
pipeline that runs offsite to Smith Creek.
A variation to this treatment scheme should be considered·:·· Although hexavalent
chromium can be reduced in a pretreatment step prior to precipitation, it can also be
removed as cr+6 by an ion exchange column after filtration step has removed any
solids. There are also other newly-developed process technologies for removal of
multivalent cations, such as ion-specific resin and magnesium oxide media. The
ultimate selection of the most appropriate process would be best accomplished during
the design stage.
The groundwater treatment system would be designed to operate 24 hours per day.
System controls would allow for complete automatic operation with minimal operator
attention. Alarms and switches would be furnished as required for fail-safe operation.
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Instruments to monitor key operating parameters, such as water flow rate, system line
pressure, and multi-media filter differential pressure, would be included.
For costing purposes, it is assumed that all treatment equipment would be leased. To
the extent possible, major equipment would be furnished skid-mounted and complete
with all piping and controls mounted on structural steel support skids.
3.6.2 EVALUATION
Overall Protectiveness
The greatest reduction in the potential risk of groundwater ingestion and inhalation
would be achieved since all contaminated groundwater would be extracted and treated
to levels acceptable for offsite surface water discharge.
Compliance with ARARs
Groundwater contaminant concentrations would meet the established cleanup goals for
the New Hanover County Airport Bum Pit Site. The treated effluent would meet the
state surface water discharge permit requirements.
Long-Term Effectiveness and Permanence
The potential for offsite contaminant migration via groundwater would be eliminated
permanently. The groundwater treatment system would require performance
specifications to ensure the adequate operation of the system. Long-term public
health risks associated with groundwater ingestion and inhalation would be eliminated.
No future site use restrictions would be required once groundwater extraction
treatment is complete.
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Reduction of M/T/V
Extraction and treatment of contaminated groundwater would achieve a maximum and
permanent reduction of contaminant mobility, toxicity, and volume in the
groundwater.
Short-Term Effectiveness
Small-scale construction activities during installation of the extraction wells as well as
operation of the mixing equipment may result in the release of minimal volatilized
contaminants, and the operation of drilling equipment would produce additional noise.
Therefore, health and safety requirements while implementing this alternative would
include periodic monitoring of organic vapors and the use of personal protection
equipment by all personnel at the site. It is assumed that Level D personal protection
would be used. Equipment and personnel decontamination facilities would also be
necessary.
Implementability
Preliminary Schedule
Approximately six months would be required for design and contractor selection.
Groundwater extraction and remediation would require approximately 4 years.
Application and successful acquisition of an NPDES permit would require
approximately six months. Assuming no major delays, this alternative could be
implemented in approximately 5 years.
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Engineering Considerations for Groundwater Extraction and Discharge
The major engineering considerations to implement the groundwater extraction and
discharge systems include:
• Design, installation, and testing of extraction well system
•
•
Potential for well plugging (reduction in flow) over time
Monitoring requirements
• Difficulty in capturing residual contaminant concentrations
•
•
•
•
Cleanup verification including the installation of three monitor wells on
the northern, western, and eastern edges of the plume
Well abandonment
Pipeline to Smith Creek
NPDES permit requirements for the surface water discharge
Engineering Considerations for Groundwater Treatment
The major engineering considerations to implement the groundwater treatment system
include:
•
•
•
•
•
•
Siting and design of treatment system
Volume of sludge generated from metals precipitation
Monitoring the effluent water quality for surface water discharge
Monitoring the sludge/filter cake generation from the metals removal
system
Determining if system-generated waste materials are hazardous wastes
under RCRA
Process effectiveness monitoring
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•
•
Ease in system operation
Provision for chemical storage
Equipment and Materials
The major system components required for operations under this alternative include:
• Submersible groundwater pumps
• Tankage, mixers, controls associated with metals removal system
• Sodium hydroxide, acid required flocculants and coagulants, and other
•
•
•
treatment chemicals ·
Pumps, piping, fittings, and valves for fluids transport
Electrical conduit and wiring for electric power and sensors
Instrumentation and controls
The major construction equipment and materials required to implement this alternative
include:
• Contractor's temporary facilities and utilities
•
•
Pipeline to Smith Creek
Front-end loader
• Backhoe
Operation and Maintenance
Long-term groundwater monitoring for cleanup verification purposes would be
required for this alternative. It is assumed that six wells would be sampled (including
two new wells) and water levels recorded on a quarterly basis for the first 4 years
(assuming 4 years for plume capture) and on an annual basis for the following
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26 years. Samples would be collected and analyzed for benzene, chloroform,
1,2-dichloroethane, chromium, ethylbenzene, and lead.
The groundwater treatment system would also require monitoring and maintenance
during its approximate 4 year operational life. Monitoring of the treatment system
would include normal troubleshooting and periodic water sampling of the influent,
midpoint, and effluent from the treatment system and analysis in accordance with the
NPDES discharge permit requirements. Collection of samples is assumed to be on a
weekly basis. Samples are anticipated to be analyzed for beryllium, chromium, lead,
pH, and any other parameters required by state surface water discharge permit. In
addition, any sludge generated would have to be packaged and disposed at an
hazardous or solid waste landfill, as applicable.
Maintenance of the extraction and treatment systems would be performed in
accordance with O&M requirements developed after equipment specification and
procurement are completed. At a minimum, it is expected that regular periodic
maintenance would be required on the pumps, valves, and fittings of fluids piping
systems, as well as on the treatment system components (cleaning of pH probes, filter
backwashing, replacement of consumable items, and sludge generation) to ensure the
efficient operation of the system.
The total present net worth cost for this alternative is approximately $2,326,958,
including capital costs of $1,132,478, and present worth O&M costs of $1,194,481,
using a discount rate of 10 percent over 30 years. The estimated annual operation
and maintenance (O&M) cost for this alternative is approximately $353,935 for the
frrst four years and $7,920 for the remaining 26 years. Detailed cost estimates are
presented in Appendix C.
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4.0 ANALYSIS AND SUMMARY OF ALTERNATIVES
This section compares and summarizes the effectiveness of each remedial action
alternative. In general, cost-effectiveness is an important criterion in comparing
treatment alternatives that provide similar levels of protection. However, cost alone
cannot be used to evaluate treatment alternatives in comparison to no action, or to
screen treatment versus non-treatment alternatives. Because the lowest cost
alternative may not satisfy remediation objectives or be protective of human health
and the environment, several factors other than cost are considered in the evaluation.
These non-economic factors include threshold criteria ( overall protectiveness and
compliance with ARARs) and primary balancing criteria (long-term effectiveness,
reduction of M/T/V through treatment, short-term effectiveness, and
implementability).
In order for a specific alternative to be selected for remediation of the New Hanover
County Airport Burn Pit Site, three main criteria must be met: the threshold criteria,
the primary balancing criteria, and the modifying criteria. This section summarizes
the evaluation of each alterative based on the threshold and primary balancing criteria.
The modifying criterion, which includes state and community acceptance, would be
evaluated by EPA and the state prior to final selection of a remedy.
Restrictions that should be considered to reduce future potential for ingestion of
contaminated groundwater are outlined in Table 4-1. Restrictions might also be
placed upon future use of the site that could compromise the integrity of the remedial
actions. For offsite areas, restrictions would be implemented to limit the use of
property where contaminated groundwater may exist in the future.
4-1
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TABLE 4-1
SUMMARY OF INSTITUTIONAL AND LAND USE RESTRICTIONS
NEW HANOVER COUNTY AIRPORT BURN PIT SITE
WII.MINGTON, NORTH CAROLINA
I: No Action Yes Yes Yes
2: Vertical Barrier Ye, Ye, Yes
3: Groundwater Extraction and Physical Treatment (Air Stripping) Yes No No
with Discharge to P01W
4: Groundwater Extraction and PhyaicaVChcmical Treatment Ye, No No
(Metals Precipitation and Air Stripping) with Discharge Via
Spray Irrigation
S: Groundwater Extraction and Physical/Chemical Treatment Yes No No
(Mctala Precipitation) with Discharge to Surface Water
lfil!!a:
u.1 Fencing rcstrictiona apply to the period of remediation only (except for no action).
Y cs Restrictions apply.
No No restrictions after remediation assuming that .AR.ARB and cleanup goals arc met.
liiiii I!!!!!!! liiiiiii iiiii
Yes Yes
Yes Ye,
No No
No No
No No
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4.1 THRESHOLD CRITERIA
Overall protection of human health and the environment and compliance with ARARs
are threshold requirements that each alternative must meet in order to be eligible for
selection.
4.1.1 OVERALL PROTECTIVENESS
Each alternative was evaluated to determine whether it is likely to effectively mitigate
and minimize the long-term risk of harm to public health and the environment
currently presented by the site. A summary of this evaluation is presented in
Table 4-2.
4.1.2 COMPLIANCE WITH ARARs
A goal of Superfund remedial activities under SARA is to attain ARARs of federal,
state, or local environmental statutes, whichever are more stringent. Federal
standards may include RCRA, the Clean Air Act, Safe Drinking Water Act, Ground
Water Protection Strategy, Clean Water Act, Toxic Substances Control Act, or Water
Quality Criteria. State standards include any promulgated by the North Carolina
Department of Environment, Health, and Natural Resources (NCDNR) and local
statutes include those promulgated by the City of Wilmington. Each remedial
alternative was evaluated with regard to its ability to comply with the ARARs, which
are generally based on acceptable levels of contamination to preserve the
environment, public health and welfare. ARARs for the site were presented in
Section 1.0.
Because the New Hanover County Airport Burn Pit Site is on the NPL, Superfund
policy and procedures are applicable. CERCLA compliance policy distinguishes
between onsite and offsite remedial actions. Environmental permits are not required
for fund-financed or enforcement actions taken at an NPL site if these actions are
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TABLE 4-2
SUMMARY OF THE PUBLIC HEALTH AND ENVIRONMENTAL EFFECTS EVALUATION
NEW HANOVER COUNTY AIRPORT BURN PIT SITE
WILMINGTON, NORTH CAROLINA
1: No Action
2: Vertical Barrier
3: Groundwater Extraction and
Physical Treatment (Air Stripping)
with Discharge to POTW
4: Groundwater Extraction and
Physical/Chemical Treatment
(Metals Precipitation and Air
Stripping) with Discharge via Spray
Irrigation
5: Groundwater Extraction and
Physical/Chemical Treatment
(Metals Precipitation) with
Discharge to Surface Water
Does not eliminate any exposure
pathways or reduce the level of risk.
Offsite contaminant migration would be
eliminated. Greatly reduces potential
risk of ingestion and inhalation.
Offsite contaminant migration would be
eliminated. Minimal operation and
maintenance of treatment system.
Eliminates potential risk of ingestion
and inhalation.
Same as Alternative 3.
Same as Alternative 3.
4-4
Not in compliance
Not in compliance
In compliance
In compliance
In compliance
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completely confined to the site (i.e., no discharge or implementation activities
performed offsite). It is anticipated that EPA will take lead responsibility in the
design and implementation of site remediation.
Compliance with ARARs for the five site remediation alternatives was evaluated in
Table 4-1. Table 4-3 identifies the federal regulations applicable to the five
alternatives under evaluation, with the exception of regulations under the Superfund
program. Table 4-4 identifies North Carolina regulations pertaining to the
alternatives. The City of Wilmington regulations are shown in Table 4-5.
4.2 PRIMARY BALANCING CRITERIA
The five primary balancing criteria are long-term effectiveness and permanence;
reduction of M/T/V through treatment: short-term effectiveness; implementability;
and cost. These are discussed below.
4.2.1 LONG-TERM EFFECTIVENESS AND PERMANENCE
These two aspects of remedial actions determine their desirability on the basis of
effectiveness and effective life. Effectiveness refers to the degree to which an action
will meet the site cleanup goals, which were derived to minimize risk to public health
and the environment. The effective life is the length of time this level of
effectiveness can be maintained. The long-term effectiveness and permanence factors
associated with each alterative is summarized in Table 4-6.
4.2.2 REDUCTION OF M/T/V THROUGH TREATMENT
The degree to which the remedial action alternative reduces the mobility, toxicity,
and/ or volume of contamination is a second factor used to determine its desirability.
An evaluation of each alternative on the basis of M/T/V reduction is presented in
Table 4-7.
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TABLE 4-3
FEDERAL REGULATIONS AFFECTING IMPLEMENTATION OF THE
ALTERNATIVES UNDER EVALUATION
NEW HANOVER COUNTY AIRPORT BURN PIT SITE
WILMINGTON, NORTH CAROLINA
National Interim Primary
Drinking Water
Standards
National Secondary
Drinking Water
Standards
Clean Air Act
40 CFR 141 Maximum contaminant levels (MCLs) for
heavy metals, anions, bacteria, pesticides,
radionuclides, and organic chemicals of
concern in drinking water. These MCLs have
been adopted as groundwater standards for the
surficial aquifer at the site because the
groundwater at the New Hanover County
Airport Burn Pit Site is classified as Class I.
EPA' s cleanup policy is most stringent for
Class I groundwater, and involves cleanup to
background or drinking water levels. Several
of these MCLs have been adopted as cleanup
goals for the site.
40 CFR 143 Maximum contaminant levels (MCLs) for
constituents affecting the aesthetic quality and
use of drinking water.
40 CFR 61 National emission standards for hazardous air
pollutants. Applicable to air stripping of
contaminants.
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TABLE 4-4
NORTH CAROLINA REGULATIONS AFFECTING THE IMPLEMENTATION OF THE
ALTERNATIVES UNDER EVALUATION
NEW HANOVER COUNTY AIRPORT BURN PIT SITE
WILMINGTON, NORTH CAROLINA
Water Quality Standards
Applicable to the
Groundwaters of the State
North Carolina Drinking
Water Quality Standards
Classification of
Surface Waters
Surface Water
Quality Standards
Coastal Waste
Treatment Disposal
Wastewater Discharge to
Surface Waters
Wastewater Discharge
to Waters other than
Surface Waters
of the State
Control of Sources of Air
Pollution
15 NCAC 2L.0200
15 NCAC 18C.1510
through !8C.1518
!SA NCAC 2B.0100
!SA NCAC 2B.0200
!SA NCAC 2B.0400
!SA NCAC 2H.0100
!SA NCAC 2H.0200
!SA NCAC 2H.0602
through 2H.0601
4-7
Classifications and water quality standards for
groundwater which is an existing or potential source
of drinking water supply for humans.
Drinking water quality standards applicable to ground-
water at the New Hanover County Airport Bum Pit
Site. Applicable to Alternatives 2, 3, 4, and 5.
Procedures for assignment of water quality standards
for surface waters. Smith Creek is a Class C surface
water. Applicable to Alternative 5.
Classifications and water quality standards applicable
to surface waters of North Carolina. Applicable to
Alternative 5.
Treatment standards to ensure compliance with water
quality standards promulgated by the North Carolina
Environmental Management Commission for
propagation of shellfish in coastal waters (i.e., Class
C waters). Applicable for discharge to Smith Creek.
Applicable to Alternative 3.
Requirements and procedures for application and
issuance of State NPDES permits. Applicable to
Alternative 5.
Requirements and procedures for application and
issuance of permits for discharge to sewer systems,
disposal systems, treatment works, and sludge disposal
systems. Applicable to Alternative 3.
Requirements and procedures to ensure compliance
with air quality standards applicable to the Staie of
North Carolina. Applicable to Alternatives 3 and 4.
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TABLE 4-5
LOCAL REGULATIONS AFFECTING THE IMPLEMENTATION OF THE
ALTERNATIVES UNDER EVALUATION
NEW HANOVER COUNTY AIRPORT BURN PIT SITE
WILMINGTON, NORTH CAROLINA
Discharge to POTW City of Wilmington Article III,
Sections 12-76 to 12-162
4-8
The City of Wilmington has
established minimum quality
standards for disposal to the
Northside POTW. Applicable
to Alternative 3.
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TABLE 4-6
LONG-TERM EFFECTNENESS AND PERMANENCE EVALUATION FOR REMEDIAL ACTION ALTERNATNES
NEW HANOVER COUNTY AIRPORT BURN PIT SITE
I: No Action
2: Vertical Barrier
3: Groundwater Extraction and Physical
Treatment (Air Stripping) with Discharge
to P01W
4: Groundwater Extraction and
Physical/Chemical Treatment {Chromium
Reduction, Metals Precipitation, and Air
Stripping) and Discharge Via Spray
Irrigation
5: Groundwater Extraction and
Physical/Chemical Treatment (Chromium
Reduction and Metals Precipitation) and
Discharge to Surface Water
WllMINGTON, NORTH CAROLINA
Docs not limit migration of or remove
contaminants. AR.ARs are exceeded.
Doea not remove contaminants, but will limit
off site migration of contaminants. ARARa are
not met.
Remove, contaminants. AR.AR, arc met.
Eliminates offsitc migration of contaminaotJ.
Same as Alternative 3.
Same aa Alternative 3.
Not applicable.
At least 30 years, but not
conside~ pcnnanent.
Permanent remedy.
Permanent remedy.
Permanent remedy.
Not applicable.
Weathering and cracking of slurry wall or
other vertical barrier.
Operator error or system failure could result
in release of contaminated effluent to sewer
connection. Pump-and-treat system1 have
difficulty removing final low concentrations
from aquifer.
Operator error or system failure could result
in release of contaminated effluent to
groundwater. Pump-and-treat systems have
difficulty removing final low concentrations
from aquifer.
Operator error or system failure could result
in release of contaminated effluent to surface
water. Pump-and-treat systems have difficulty
removing final low concentrations from
aquifer.
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No Action
Vertical Barrier
Groundwater Extraction and Physical
Treatment (Air Stripping) wi.th
Discharge to P01W
Groundwater Extraction and
Pbyaical/Chcmical Treatment
(Chromium Reduction, Mctala
Precipitation, and Air Stripping) with
Discharge Via Spray lnigation
Groundwater Extraction and
PhyaicaVChcmical Treatment
(Chromium Reduction and Metals
Precipitation) with Discharge to Surface
Water
11!!!!!!!1 I!!!!!!! !!!!! I!!!!!!! == == liiiiiiii liiiiiii
TABLE 4-7
SHORT-TERM EFFECTIVENESS AND IMPLEMENT ABILITY EVALUATION
NEW HANOVER COUNTY AIRPORT BURN PIT SITE
WIIMINGTON, NORTH CAROLINA
Poses no short-term risks.
Small-scale construction DlllY result in the potential
release of a minimal amount of volatile organics.
Noise nuisance from treatment equipment.
Small-scale construction may result in the release of
volatile organic emissions from the groundwater. Air
emissions and noise nuisance from treatment
equipment.
Same as Alternative 3 and residual sludge/filter cake
would be generated from filter backwashing process.
Air cmiaaiona and noise nuisance from ttutmcnl
equipment.
Residual sludge/filter cake would be generated from
filter backwashing proccaa.
None.
Design and construction of impermeable cap and
vertical barrier.
Recovery of the full extent of the estimated
groundwater plume could take a long time.
Treat.ability testing of treatment system would be
required to demonstrate ultimate effectiveness.
Possible difficulties in acquiring POTW discharge
permit.
Same as Alternative 3. Design and construction of
spray irrigation system necessary and special
considerations for wet weather under freezing
temperature conditions.
Same as Alternative 3. Design and construction of
4,000-foot discharge pipeline and outfall neceuary.
Possible difficulties in acquiring NPDES discharge
permit.
Iii!!!! l!!!I
Immediately
1.5 yean
4.5 years
4.5 yean
5.0 years
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4.2.3 SHORT-TERM EFFECTIVENESS
Each alternative was examined to determine whether the alternative itself or its
implementation would present any significant risks to public health or the
environment. This evaluation generally involves short-term risks that would occur
only while the alternative is being implemented. A temporary disruption to the
habitat in the immediate New Hanover County Airport Burn Pit Site area would result
from implementing any of the groundwater remedial alternatives. Additional possible
risks include airborne releases of pollutants. The short-term effectiveness evaluation
of each alternative is summarized in Table 4-7.
4.2.4 IMPLEMENTABILITY
For each alternative, constraints to implementation, such as difficult engineering
requirements, the availability of equipment or offsite facilities, and permit and
treatability/pilot study requirements, are considered. Also evaluated under this
category are the labor and time requirements to attain the desired results should the
alternative be implemented. These considerations are summarized in Table 4-7.
4.2.5 COST EVALUATION
The present worth of each alternative provides the basis for the cost comparison. The
present worth cost represents the amount of money that, if invested in the initial year
of the remedial action at a given rate, would provide the funds required to make
future payments to cover all costs associated with the remedial action over its planned
life .
The present worth analysis was performed on all remedial alternatives using a 10
percent discount (interest) rate over a period of 30 years. Inflation and depreciation
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were not considered in preparing the present worth costs. The present worth costs for
the remedial action alternatives are summarized in Table 4-8. Appendix C contains
spreadsheets showing each component of the cost summarized in Table 4-8.
4.3 SUMMARY
A detailed evaluation of the remedial action alternatives in terms of cost and non-cost
criteria was described in Section 3. A summary of this evaluation is presented in
Table 4-9 to concisely show the major differences among the remedial action
alternatives with regard to the criteria used: technical effectiveness and
implementability, environmental and public health risk, institutional requirements, and
costs.
4-12
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liiiiiiil liiiiiiil lliiiiiiil liiii liii!iiil liiiil liiiliiil l!i!iii!iil li!i!ii!iii li!iiiii! l!i!!J!!§ l!iiil
TABLE 4-8
SUMMARY OF PRESENT WORTH COSTS FOR REMEDIAL ACTION ALTERNATIVES
NEW HANOVER COUNTY AIRPORT BURN PIT SITE
WIIMINGTON, NORTH CAROLINA
1: No Action
2: Vertical Barrier
3: Groundwater Extraction and Physical Treatment {Air Stripping) with Discharge to P0TW
4: Groundwater Extraction and Physical/Chemical Treatment (Chromium Reduction, Metals
Precipitation, and Air Stripping) with Discharge Via Spray Irrigation
5: Groundwater ExtractioQ and Physical/Chemical Treatment (Chromium Reduction and Metals
Precipitation) with Discharge to Surface Water
lfilm:
(l.) Present worth of O&M Costa for 30 years using a 10 percent interest rate.
Detailed costs arc presented in Appendix C.
0
925.9
805.6
1,053.9
1,132.5
l!!!!!!!I I!!!!!! l!!!!!!!I l!!!!!I
74.7 74.7
161.8 1,087.7
1,074.2 1,889.9
1,265.2 2,319.2
1,194.5 2,326.9
== == == ==
I: No Action Ongoing monitoring of
groundwater contaminant
levels would be conducted
to assess contaminant mi-
gration. Docs not meet
ARARs.
2: Vertical Barrier The potential for offsite
contamination migration is
greatly reduced. ARARs
are not met at the site.
Length of service un-
known (not permanent).
;:;:a ;;;;a ==
TABLE 4-9
SUMMARY OF ALTERNATIVES EVALUATION
NEW HANOVER COUNTY AIRPORT BURN PIT SITE
WILMINGTON, NORTH CAROLINA
None. None. None.
Greatly reduces Potential release of Design of slurry wall and im-
mobility. No reduction organic volatiles dur-permeable cap; stormwater
in toxicity and volume. ing slurry wall instal-runoff drainage and collection
lation. Noise nuisance for cap. Air monitoring during
due to operation of implementation.
heavy equipment.
0 74.7
1.5 1,087.7
NHANF009.0J8
l!!!!I ~ ==
3: Groundwater
Extraction and
Physical Treatment
(Air Stripping)
Wl1h Discharge to
POTW
== ==
Permanent remedy.
ARARsarcmct.
r:;;;; liiiiiiiil
Eliminates MrrN of
contaminants. Elimi-
nates potential for
offsite migration. High
degree of risk reduction
for ingestion and inha-
lation of groundwater.
liiiiiiiiiil li!iiiiil l!!!!!i!!I
TABLE 4-9
(continued)
Potential release of
organic volatiles dur-
ing extraction and
treatment system
operation. Noise
nuisance due to
operation of d~g
equipment.
Design of extraction, treatment,
and discharge systems. Air
stripping of benzene to "below
detection limil" required.
Treatment of air stripping off-
gases may be required. Pre-
treatment for TSS and iron may
be required. Discharge permit
acquisition under consideration.
Ongoing monitoring of ground-
water contaminant levels and the
treatment system should be con-
ducted to assess extraction and
treatment systems performance.
Must meet City of Wilmington
POTW discharge requirements
and CAA requirements. No
future land use restrictions
would be required.
1!!!!!!!11 l!!!!!I
4.5 1,889.9
NHANFS09.0l8
--- ---
4: Groundwater Permanent remedy.
Extraction and Physi-ARARs arc met.
cal/Chemical Treat-
ment (Chromium
Reduction, Metals
Precipitation, and
Air Stripping) with
Discharge via Spray
Irrigation
- -
Eliminates MrrN of
contaminants.
Eliminates potential for
offsitc migration.
Greatest degree of risk
reduction for ingestion
and inhalation of
groundwater.
!!!!I l!!!!!I
TABLE 4-9
( continued)
Potential release of
organic volatiles dur-
ing extraction well
installation. Noise
nuisance due to opera-
tion of drilling
equipment.
Sludge/filter cake
generation from pre-
cipitate.
== liiii:iil liiiiiiil
Design of extraction, treatment,
and discharge systems. Metals
precipitation should achieve
requi=I North
Carolina Drinking Water Quali-
ty Standards for inorganics. Air
stripping should achieve stan-
dards for organics. Treatment
of air stripping off-gases may be
requi=I. Pretreatment for TSS
and iron may be requi=I.
Storage may be required during
wet weather and under freezing
temperature conditions. Ongo-
ing monitoring of groundwater
contaminant levels and the
treatment system should be con-
ducted to assess extraction and
treatment systems performance.
Must meet North Carolina
Drinking Water Quality Stan-
dards for groundwater and CAA
emissions requirements.
iiiiii!! li!!!!!!i !!!!I
4.5 2,319.2
NHANFS09.038
-- - -
5: Groundwater
Extraction and Phys-
ical/Chemical
Treatment (Chromi-
um Reduction and
Metals Precipitation)
with Discharge to
Surface Water
- -
Permanent remedy.
ARARs are met.
--~
Eliminates MrrN of
contaminants. Reduce
source of groundwater
contamination. Great-
est degree of risk re-
duction for ingestion
and inhalation of
groundwater.
!!!!!I l!!!!l!!I i::= == liiiiiil
TABLE 4-9
(continued)_
Potential release of
organic volatiles dur-
ing extraction well
installation. Noise
nuisance, due to oper-
ation of drilling
equipment.
Sludge/filter cake
generation from pre-
cipitate.
Design of extraction, treatment,
and discharge systems. Metals
precipitation should achieve
North Carolina Surface Water
discharge requirements for
inorganics. A 4,~foot
pipeline would be required for
discharge to Smith Creek.
Permit acquisition under
consideration. Ongoing
monitoring of groundwater
contaminant levels and the
treatment system should be
conducted to assess extraction
and treatment systems
performance. Must meet North
Carolina Surface Water dis-
charge requirements.
Ii!!!!!! 11!1111
5 2,326.9
NHANFS09,038
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REFERENCES
Bain, G.L. 1970. Geology and Groundwater Resources of New Hanover County,
North Carolina. U.S. Geological Survey Division of Groundwater, Groundwater
Bulletin Number 17, 72 p.
CDM Federal Programs Corporation. April 1992. Final Risk Assessment Report for
the New Hanover County Airport Burn Pit Site, Wilmington, North Carolina.
Choppin and Johnson. 1972. Introductory Chemistry.
Cushnie, George C., Jr. 1984. Removal of Metals from Wastewater. Noyes
Publications, Park Ridge, New Jersey.
Knox, R.C., et al. 1986. National Center for Ground Water Research, University of
Oklahoma, Aquifer Restoration State of the Art.
Noonan, D. and J. Curtis. 1990. Groundwater Remediation and Petroleum: A
Guide for Underground Storage Tanks, Lewis Publishers.
Patterson, James W. 1985. Industrial Wastewater Treatment Technology.
Butterworth Publishers, Boston, Massachusetts.
U.S. Environmental Protection Agency, Office of Research and Development,
Cincinnati, Ohio. April, 1980. Carbon Absorption Isotherms for Toxic Organics.
U.S. Environmental Protection Agency. 1989. Evaluation of Groundwater
Extraction Remedies.
U.S. Environmental Protection Agency, Office of Groundwater and Drinking Water.
May 1991. Fact Sheet: National Primary Drinking Water Regulations for Lead
and Copper.
U.S. Environmental Protection Agency, Office of Emergency and Remedial
Response. October 1988. Guidance for Conducting Remedial Investigations and
Feasibility Studies Under Comprehensive Environmental Response, Compensation,
and Liability Act of 1980 --Interim Final.
U.S. Environment Protection Agency. January 1992a. National Oil and Hazardous
Waste Contingency Plan Under Comprehensive Environmental Response,
Compensation, and Liability Act of.1980 (CERCLA).
R-1
NHANFS09.019
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U.S. Environmental Protection Agency, Region IV, Environmental Compliance
Branch, Hazardous Waste Section. January 1992b. Remedial Investigation, New
Hanover County Airport, North Carolina.
U.S. Environment Protection Agency. January 1992c. National Emission Standards
for Hazardous Air Pollutants, Code of Federal Regulations, Title 40, Part 61,
U.S. Government Printing Office, Washington, D.C., 1973-1990.
R-2
NHANFS09 .019
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APPENDIX A
BORING AND WELL LOGS
NHANFS09.022
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A USEPA Region IV MWD-001 Boring Log and Page ~ ESD/ECBIHWS Well Construction Details lofl
PROJECT ill: 91£-019 DRILLER: Charles Till, PG
SITE: New Hanover Burn Pit GEOLOGIST: Jonathan va,1
LOCATION: Wilmington, NC DATE: 04/12/91
~ !,l :c W<C ~ ... -f§ DE~lfG'l."lftoN i:8 .... GEOLOGIC OESCRJPTION WELL OJAGRAM WELL SPECJFICA TIONS ~ ~~ ::, 0 "'= ..
-5-.
.
. -a Top or ~asing 2.4 rt aoove gound •
.
0 -SM ti ~ANO. with ,, sand'!¥"" Q ~~ 1,,;oncrete Pad 8" thick, • sQu•e .. Concrete to 2 ft BLS . .. . . ril 1ng oertormed with e.2 ', ' .. hollo• stem augers. ~~< 0 . 7 7 Vtil'19,•tt?nitg ~•out ~o . [/ t • L 10. IDs/gal
. -~ . . .. / 5 -/ . V, .. .. .. > .. / . .. .. ;~ . . . .. / / 10-. ~ ~ . / .. : V, . ,· . .. .. / [/
' / . .. . , v; 15-.. / ~ -. ,and rack to •• rt ~L, . .. . . . I OP 01 ,creen vu.,. rt_ lot.S . ~ 20-.. .. Screen is 2' 0.0lr Wir, . ~ Wound Stainless IHI ASTM 304) .. .. Filt!f Pack is 20•40 Flint Sand, .. cu•l7Q .. .. ~ .. ~ .. ~ . . . . .
25-~ ~
~ . ~ . .. . . . . . -
Pyi~rtv· i CL
Bottom o, ..... ,~en '7,JQ ft RIC:
Hollow stem au~rinp Bottom Cl Wei •• , .• , rt BLS X terminate~ at ! f BLS AMPLE 3" ShelDy uDe ample collected
30-for. permeacmtr analosis, samole inteoa 28-3 .5 ft -. ~ottom I erminated at ,u.> rt ~L~ Bottom 01 ~cring 130.> rt ~L~
.
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A USEPA Region JV MWS-001 Boring Log and Page ~ ESD/ECB/HWS Well Construction Details I of/
PROJECT ii: 91£-019 DRILLER: c11artes Tl'll, PG
SITE: New Hanover Burn Pit. GEOLOGIST: Jonat/lan Vail
LOCATION: Hl'lmington, NC DATE: 04/11/91
:z:_ "'" u
t.:1: jffi OE!tt:lfioN ~8 ~ GEOLOGIC OESCRIPTION WELL OIAGRAM WELL SPEC!FICA TIONS ~ ~ i"' :::,
-5-NA
.
~
~ i Top 01 ,asing 2.SJ ft aoo,e ground, .
.
G ~ 0 -concrete Pad o" thick, J sQuare SM suty SANU, tan .. ,. b Concrete to _LS ft BLS . •, b ·: .. i; ~ .... Volclay _nntonit• . .i•• 7.ut to " ~ . 2.4 ft BLS (10.2 lbs gal) ~ ·: •. B.entoniJ• .!'tUets to . ~ 3.4 ft LS SM suty SANO, orown ~ 5ana Pack to 15.5 .ft ~L:, .
5 -" t Top or 5CrNn 14.5 ft Bl5
. [ . ~ SM :iAN□, creamy white to 1t\~•Q g . Sil y N with SP sand layers
.
E Screen is 2' 0.01g' Wir, .. Wouna Stainless ltet ASTM 304) . . .. 10-..
~ Fite, Paci is 20-40 Flint Sand, " cu•L19 .. . . .
,,
. ~ . . . ~ . . . . ..
. . . . . .. ~
" . 15-MOltom or r 114. II .. Bottom.of weu 014.Sa It 1:11.5 . .
Boring Term,natea at 15.5 It. Bottom ol Boring 015.o It ~L5 .
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-· ·---'1z USEPA Region JV MW0-002 Boring Log and Page ESO/ECBIHWS Well Construction Details /of/
PROJECT I: 91£-019 DRILLER: Charles Till, PG
SITE: New Hanover Burn Pit GEOLOGIST: Jonathan Vail
LOCATION: t•mmington, NC DATE: 04115/91
.,./ u . i:-i OE!1'ce."HtoN :i:8 "' .... bl GEOLOGIC DESCRIPTION WELL DIAGRAM WELL SPECIFICATIONS ~ "'! ~~ ::,
-5-NA .
.
~ ii Top of Cumg 2.,v II aoove gound, .
.
0 -... SM oill7i 5ANO, ._,ith ~,. sana 1giers ~ ~ Concrete Pad 8 .. thick, J sciuare " . riling Per formed with 8.2 ,l Concrete to t5 II BLS hollow stem aygers. . ,, .,
VOl~an R•ntonil! Grout lo r/ t•. LS (10. ll>s/ gal) . .. I/ r/ . r~ I ..
5 -r/ . •, r/
,
/ .. / . ,
. ..
/ /
10-/ './ i:,., > . / / I'/ ./ . I/ /
I/ ~ .
/
/ > . ;.. -.. .. . . sana Pack to ,, .5 ft BLS 15-·.· . . . ..
.
~ Top 01 Scrffn &If"' II BLS .
. .. .. i 20-... .. Screen is 2• o.oig• Wlr~ . i Wouna StainleU IHI ASTM 30•) . . ..
Fitter Pack is 20-•o Flint Sand, ... cu•l.7a .
. .~
[ 25-
. ..
.. ~ . '.'''
Boring l erminatea at 27., fl BLS ttom ot c:.crE~j. ft 01..: .
""\' m nf W•II '.-:ii ft 1c . Bottom of earing t21 .5 II BLS
30-
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A USEPA Region IV tvlWS-002 Boring Log and Page
~ ESO/ECBIHWS Well Construction Details I of/
PROJECT f; 9tE-0l9 DRILLER: c11ar1es rm. PG
SITE: New Hanover Burn Pit GEOLOGIST: Jonathan Vail
LOCATION: Wilmington, NC DATE: 04/15191
:,: i !:! "' ... -0£!1~%0N i:8 ~ fl! GEOLOGIC DESCRIPTION WELL DIAGRAM WELL SPEC!F!CA TIONS
"! ~ .. ::,
-s-NA
.
. -= i Top ot ~a sing 2.83 It acove ground,
.
B ~ 0 -
concrete Pad 6" thick, J' square
.. SM silty ::>AN\J, "Nitl'l·sl" sand layers Concrete lo lO ft BLS
" -. J 0
. ~
.. , ·,-e_entinII" Pellets to
·.·. :, 3.0 t LS
... ,·
. ·-.· ~ .. .•~
. ..:,
.
,_ .a: Sand Pack to 15.5 It BLS
.
5 -§ rop 01 Scrnn •4,g4 It BLS
. ... ...
t:.
.. § ..
. "
... ... ... ...
" ·-
~ Screen is 2• 0.0lg' w~, ... wound Stainless Itel ASTM 304) ...
10-" '• E ... FUter Paclt is 20-40 Flint San<!.
,,
... cu•l7Q
. •,
...
. '• ~ " ...
. "
... ...
" " ~ .
"
... ...
... ·.·.
...
. ...
.. '
...
.. ~
15-.. m "' r ili14,, ,,
Bottom of Well 014.88 It SLS
Soring ierminated at 15.5 It. oottom of Boring 115.5 It BLS
.
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·-A USEPA Region IV MWS-003 Boring Log and ~ Page
ESD/ECB/HWS Well Construction Details I off
PROJECT I: 91£-019 DRILLER: Charles THI, PG
SITE: New Hanover Burn Pit GEOLOGIST: Jonathan Vail
LOCATION: HHmington, NC DATE: 04/13/91
J u ~-.. c
fffi ~•M't-n ls 1/) c..U ~ GEOLOGIC DESCRIPTION WELL DIAGRAM WELL SPECIFICATIONS ~ 0! IClNA ON iJ "'!
-5-NA
.
. -ii . Top ot Casing 2.,u II acove gounc1, .
.
0 ~ 0 -SM silty SANO, dark Clack concrete ,.., 8" 1nick, l' sQuare
~ 0 Concrete to to It BLS
&. ~
r.1 ~ V_Q!!:lfiY-Brtonite er0111 to .. i;: 2.0 I BL (10.11111/glll) :
" ~ : .-:. . . ' ·, B_entoniJe re11eu to -~ ·, l.0 II LS . ::::,; ;..
~ .. a Paek to 17.0 It BLS
..
5 -~ Top of ScrNn ft BLS
.
SM Sil~ SANO. Qark tnown. with " S sand layers ~ . f .. ..
. . . .. ~
.. . E .
~ Screen ~ 2• 0.0~• w1r~ . wouno tlinlall teal ASTM 30•) 10-
" Filler Pr=• is 20-•0 Flint Sano, •, cu•L7
" .. ~ . ·.· ..
. ..
~ .
'•' . ~ . "
~
15-.. II '"•f 111,&, It
" Bottom of Wed 115.ol fl BLS
"
.
Boring T ermrnateo at 11.TII. Bottom or Boring lt7.0 ft BLS
.
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ft USEPA Region JV MWS-004 Boring Log ana ~ Page
ESDIECB/HWS Well Construction Details I of I
PROJECT #: 91£-019 DRILLER: Charles T,71, PG
SITE: New Hanover Burn Pit GEOLOGIST: ·Jonathan Vail
LOCATION: Hilmington, NC DATE: 04/13/91
~-.,al u ..... fffi O~f1f.1'A'-rtON I§ ~ GEOLOGIC DESCRIPTION WELL DIAGRAM WELL SPECIFICATIONS w.!! Q cn3
-5-NA
.
. -~ i , op of Casing 2.1~ rt aoo,e ground, .
.
G ~ 0 -Concrete P6d tr' thick, l sQuare SM silty :SAN □, with ~,. sane layers ,, b Concrete to LO fl 8LS . ~ ~ Volctay_B\ntonite Gr7,ut to .. 2.0 It BL (lO.l Ills gal) . " ,., . L" ---Sl~f{'°JfseHets to .... ~ ~ ---Sand Pack to 18.0 ft BLS
-
" •.
5 -" " ~ Top Of Screen .,.u, It BLS
.
" " § . .
. ~ •
~ . ~
~ Screen Is 2• 0.0ig• Wir, Wound Stlinless tell ASTM 304) 10-Filter ffk is 20-40 Flint Sand, .. cu•L , . " ~ ..
" .
" " ~ " "
. .. '• ~
15 -" nl r ., .. ., .. ,.
Bottom ol Wed 114.98 fl SLS
Boring l erminated at 16.0 It. Bottom ol Boring 118.0 fl 8LS
.
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A USEPA Region JV TB-01 Boring Log aria Page ~ ESD/ECBIHWS Well Construction Details tofl
' PROJECT f: 91£-019 DRILLER: Charles Till, PG
SITE: New Hanover Burn Pit· GEOLOGIST: Jonathan Vail
LOCATION: Hi/ming/on, NC DATE: 04/09/91 .
i=-..,:i " ..... f~ fAMPLf: ls ~ GEOLOGIC OESCRIPTION WELL OIAGRAM WELL SPECIFICATIONS ~ 0! lGNA ION i"' ::, "'!
0 -. ~ I~ f\ s11ck sand] L~~-~• ro~! zone. I No Wea Installed >::: ... rillinl"'.I· ;.._., • I .i.u r . SM silty line ~ANO, t>IICk Ind grey .
.
5 -SM
.
silty lin"s ~•Nu. yellow-tan-white, wet at II • . . SP fine ~•Nu, non•p1astic white " .. . 10-..
. . SM Silto iAN,□, with ~,. sana layers 15-" UA 13' ... Una011 to continue drilling with . " stat auger due to cave 1n. . ·. Drilling continued •ith mua rotary . . . 20-.. .
• . . .
" . ..
25-. . . . CL Sllty ,LAY, film, lignt to dirk grey 3~
. . 35-SP line SANO ' ' . .
40,:
. .· .. !:: ~ SANu and ,LAY lenses . SP m,edium to COltSt gtllnt<I QllltlZ SANL . liQl,t grey 45-
" .
'
. . ·:.· . . .. so-...
'• . . '• .. . ,, . ... -:.· 55-.. . . .. . . .
6~ ~ NX CORE Au .. r us.-1 NX r• to . X ~ARRE~ san0y tossdit~o~LL 0M~~.,, '{~E • AMPL Ol'l"'•""natic --1-i . 0-11 ' . ~ louilite,ius fi~~~ I NE • 65-'-calcite. 1-8 It. · . sandy lo~~ihl8e!°u1 LIMES, ONE, ,.,c,te. -8 .5 t. . fossili_l~iu_,s L1~1r I uNE, --•!cite. 1}i•6 t 70-Boring Terminated at o, ft.
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A ~ USEPA Region JV
ESOIECB/HWS
PROJECT f: 9/E-019
SITE: New Hanover Burn Pit
LOCATION: Hilmington, NC
TB-02 Boring Log and
Well Construction Details
DRILLER: Charles Ti/I, PG
GEOLOGIST: Jonathan Vail
DA TE: 04/11/91
Page
I of/
GEOLOGIC DESCRIPTION WELL DIAGRAM WELL SPECIFICATIONS
0 -
.
.
5 -.
.
.
.
10-
.
.
.
.
15 -
.
.
.
.
20-
.
.
.
.
25-
.
. '
.
30-
.
'
.
35-
NA ...
. : .
. . . : .
' ...
SM
SM
CL
lilly --S-AN1l dark Olack
Boring pe,}ouned with .t'" solid
stem auaers to ascertain depth
of clay raver acrou site .
Silty SANO, oark brown Nilh ~r
sand layers
7:LAY, blue-gay
retrieved with 4" ~111t .........
Boring 1 erminated at 32 It
NO Wei lnstaUed
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~ USEPA Region JV
ESD/ECBIHWS
PROJECT I; 9/E-019
SITE: New Hanover Burn Pit
LOCATION: Hilmington, NC
TB-03 Boring Log and
Well Construction Details
DRILLER: Charles Till, PG
GEOLOGIST: Jonathan Vail
DA TE: 04/11/91
Page
I oft
GEOLOGIC DESCRIPTION NELL DIAGRAM NELL SPECIFICA T!ONS
0 -NA
.
.
.
5 -
.
.
.
10-
-
-
-
-
15-
-.
.
20-
.
-
' -
-
25-
-
.
.
-
30-
·:.
" --
.. ..
. ...
._. '•
.. ·.·.
" .. . .
. . .. . . .
....
S14 lilly SANO-,l ... itn SP sand layers
Soring cer ormed •ith ,. .. solid
stem auoers to asc11tttain deolh
of ctay rayer across site.
e!§3 CL CLAY, Dive-gay
Boring Terminated at ,o ft
No Nea Installed
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APPENDIXB
GROUNDWATER ANALYTICAL RESULTS
NHANFS09 .022
---- --1!11!!!1 1!!!!!!11 ;a l!Jl!!ii Ii!!!!!! !!!!!I
TABLE B-1
FIRST ROUND GROUNDWATER DATA SUMMARY-APRIL 1991
NEW HANOVER COUNTY AIRPORT SITE
WILMINGTON, NORTH CAROLINA
Inoreanic Elements (µg/1)
Aluminum 52,000 56,000
Barium 99 160
Calcium 25,000 22,000
Chromium 82 72
Copper 21 17
Iron 12,000 28,000
Magnesium 3,200 7,700
Manganese 99 360
Nickel 36 23
Potassium 3,200 4,800
Sodium 37,000 37,000
Strontium 250 480
Titanium 180 310
Vanadium 56 73
Yttrium IOU 17
Zinc 52 53
Pesticide/PCB Compounds
NOTES:
I -Estimated value
N -Presumptive evidence of presence of material (tentative identification).
U -Material was analyzed for but not detected. Value is quantitation limit.
-Not detected in the sample.
36,000 46,000
370 290
38,000 28,000
60 58
17 12
40,000 22,000
12,000 7,000
490 130
69 69
9,000 11,000
260,000 250,000
640 160
300 220
63 67
13 17
62 40
== li!1iii
58,000 16,000
92 50
6,300 8,600
65 71
14 IOU
11,000 6,100
2,800 2,600
61 59
33 110
3,500 2U
9,700 6,100
56 59
190 85
60 20
IOU IOU
40 40
NHANOIS.027
- -- --l!!!!!!I
Extractable Organic Compounds (µg/1)
Bicycloheptyl
[(Butoxyethoxy)ethoxy]ethanol
Dihydrodimethylindcne
Dihydromethylindene
Dihydronaphthalenone
Dimethylnaphthalene
2,4-Dimethylphenol
Dimethylphenol (Not 2,4-)
Ethyldimethylbenzene (2 Isomers)
Ethyldimethylbenzene (3 Isomers)
Ethyldimethylbenzene (6 Isomers)
1-Methylnaphthalene
2-Methylnaphthalene
2-Methylphenol
Methylbenzeneacctic Acid
Methylbenzenemethanol
Methylpyrrolidinone
Naphthalene
Naphthalic Anhydride
Tetrahydromethylnaphthalene
Tetrahydronaphthalene
NOTES:
J -Estimated value
!OU
!OJN
4JN
!OU
!OU
!OJN
3JN
20JN
!OU
3JN
4JN
li!iiil
TABLE B-1
( continued)
3JN
3JN
SJN
6JN
2.3]
4JN
20JN
20JN
60J
2.1]
20JN
6JN
N -Presumptive evidence of presence of material (tentative identification).
U -Material was analyzed for but not detected. Value is quantitation limit.
-Not detected in the sample.
l!!i!!i!!I
40JN
42J
60JN
6.!J
SOJN
llJ
54
20JN
!OOJN
!6J
5.!J
91
==
SJN
!OU
!OU
== ;;;; liiiiiiil
20U
20U
ZOU
20U
NHANOU.027
l1iiiii
---- -
l!!!!!!!I
Extractable Organic Compounds (µg/1)
(continued)
Tetrahydrothiophenedioxide
Trimethylbenzoic Acid (3 Isomers)
Trimcthylhexanoic Acid
2 Unidentified Compounds
5 Unidentified Compounds
Purgeable Organic Compounds (µg/1)
Benzene
Carbon Disulfide
Chloroform
1,2-Dichlorocthane
Ethyl Ether
Ethyl Benzene
Ethylmethylbenzene
Methoxymethylpropane
Toluene
Total Xylenes
Trimethylbenzene
Trimethylbenzene (3 Isomers)
Trimethylbenzene (2 Isomers)
J -Estimated value
1!111
20JN
4JN
3.5]
25U
2.IJ
IOU
90JN
3.3]
JO.SJ
TABLE B-1
(continued)
40JN
7.9]
25U
IOU
IOU
300JN
8.5]
IOJN
2.0J
25.3]
80JN
N -Presumptive evidence of presence of material (tentative identification).
U -Material was analyzed for but not dete.cted. Value is quantitation limit.
-Not detected in the sample.
I!!!!!!!
500JN
700JN
2001
110
62U
25U
4.4]
34
14]
82]
80JN
l!!!!!!!I
600JN
1,000JN
900]
110
120U
sou
sou
43]
200JN
5.81
19.4]
60JN
==
!U
I.SJ
2.9]
0.89]
SU
;;;;;a liiii
!U
12U
1.21
SU
SU
NliAN015.027
I!!!!!!!
---- -
Purgeable Organic Coml!Qunds (µgn)
Benzene
Chloroform
1,2-Dichloroethanc
Dimethyl Pcntanonc
Ethyl Ether
Ethyl Benzene
Ethy!mclhylbenzene (2 Isomer,)
Methoxymcthylpropanc
Methoxypropanol
Methyl Ethyl Ketone
Melhylpropanol
Tetrahydrothiophene
Toluene
Total Xylenes
Trimethylbcnzcnc
Trimethylbenzcnc (2 Isomers)
Trimethylbenzcne (3 Isomers)
fillm,
J Estimated value
l!!l!!!I 11!!1 l!!!!i!!!I I!!!!!!
TABLE B-2
SECOND ROUND GROUNDWATER DATA SUMMARY -MAY 1991
NEW HANOVER COUNTY AIRPORT SITE
WILMINGTON, NORTH CAROLINA
1.1 7.7 I.OU I.OU
3.41 1.11 1.61 O.Sll
s.ou s.ou s.ou s.ou
301N 2001N
1.21 7.4 s.ou s.ou
201N
sou sou sou sou
101N
s.ou I.SI s.ou s.ou
4.11 21.91 s.ou 0.111
SIN
601N
N Presumptive evidence of presence of material (tentative identification).
U Material was analyzed for but not detected. Value is quantitation limit.
Not detected in the sample.
!!!!!I ~ == Ciiiiiiil liii1il
31 94
I.SI 2SU
IOU 2.71
401N
9.21 30
1001N 1001N
SOIN
641 2S0U
20JN
201N
2.Sl 131
9.11 821
SOIN
301N
--- - --
Inorganic Elements (µgfl)
Aluminum
Barium
Beryllium
Calcium
Chromium
Cobalt
Copper
Iron
Lead
Magnesium
Manganeac
Molybdenum
Nickel
Potassium
-== li!!ii!I
TABLE B-3
THIRD ROUND.GROUNDWATER DATA SUMMARY -NOVEMBER 1991
NEW HANOVER COUNTY AIRPORT SITE
WllMINGTON, NORTH CAROLINA
16000 6600 6200 4500 4700
260 n 75 12 130
l.4 I.OU I.OU I.OU I.OU
13,000 18,000 18,000 2,800 17,000
34 14 12 4.2 ll
2.0U 2.0U 2.0U 2.0U 2.2
ll 6.2 5.2 2.0U 3.2
16,000 17,000 16,000 1,200 19,000
22 8.0U 8.0U 8.0U 8.0U
1,900 4,600 4,600 230 3,800
41 280 280 2:6 84
2.0U 2.0U 2.0U 2.0U 2.0U
18 4.9 4.1 4.0U 8.1
1,600 2,900 2,800 540 6,600
330
410
I.OU
31,000
30
2.0U
2.7
33,000
8.0U
8,800
350
2.0U
5.8
7,500
Sodium 31,000 43,000 43,000 870 140,000 240,000
Strontium 120 290 290 16 100 350
Titanium 64 44 41 42 19 10
Vanadium 19 9.5 9.3 6.0 41 12
Yttrium 7.7 2.8 2.7 2.0U 12 3.6
Zinc 23 17 15 2.6 14 6.1
NOTES,
J Estimated value.
N Presumptive evidence of presence of material (tentative identification).
U Material was analyzed for but not detected. Value is quantitation limit.
Not detected in the sample.
== liiiiil
2400 6700 40U
40 34 2.0U
I.OU I.OU I.OU
5,800 6,100 100
8.1 31 2.0U
2.0U 2.0U 2.0U
2.3 3.2 3.4
5,000 1,800 22
8.0U 8.0U 8.0U
1,300 1,700 20U
21 13 2.0U
2.7 2.7 2.0U
5.5 16 4.0U
880 760 400U
10,000 8,400 82,000
40 34 2.0U
17 22 6.1
5.1 6.7 2.0U
2.0U 2.0U 2.0U
9.7 21 7.7
- -- -
1!!!!11
Extractable !2!K,anlc Comt2,ounds (µg/l)
Bcnzoic Acid
Butoxycthanol
Dicthylb"enzcnc
Dihydrodimethylindenc
Dihydromethylindene
Dihydromcthylindcne (2 isomers)
Dihydromethylindcnonc 6JN
Dihydromcthylnaphthalcnc
Dihydronaphthalenone 2JN
Dimethylbenzofuranonc 1/N
Dimethylbcnzoic Acid
Dimethylisobenzofurand.ione (2 isomers)
Dimctbylisobcnzofurandionc
Dimcthylnaphthalcne (3 isomers)
Dimethylnaphthalcnc (2 isomers)
2,4-Dimcthylphcnol IOU
Dimcthylphcnol (not 2,4)
(Dimethylphcnyl)cthanonc IIN
Ethyldimethylbcnzene (2 isomers)
Hcxanoic Acid
Mcthoxymcthylbcnzene
Methyl(propcnyl)bcnzenc
Mcthylbenzcneacctic Acid
Methylbenzeneacctic Acid (2 isomers)
(McthylmcthylpropyQbcnzcnc
NOTES:
J Estimated value.
N Presumptive evidence of presence of material (tentative identification).
U Material was analyzed for but not detected. Value is quantitation limit.
Not detected in the sample,
JIN
1/N
2JN
20JN
8JN
7JN
30JN
3.61
3JN
8JN
SJN
30JN
TABLEB-3
(continued)
1/N
SJN
IOJN
30JN
3.41
9IN
2JN
IOJN
20JN
8JN
IOU
li!!!!!!!I l!!!!!!!!I == == ;;;.
20IN
IOOJN
60JN
22J 411 IOU IOU IOU
701N 401N
401N
JIN
2001N
-iiiiiii ii!l!I l!!!!!!!ll!I
Fxtractabk Qrg_anic Com(!!lunds (µg/1)
(conlinued)
1-Mcthylnapbthalcne 8/N 20/N
2-Mcthylnaphthalenc IOU 19
Methylnaphthalcneacctic Acid
2-Mcthylphenol IOU 3.8/
3-and/or 4-Mctbylphenol IOU 2.91
Mcthylpyrrolidinonc 40/N
Mcthylpyrrolidone
Naphthalene 1.51 21
Naphthalcneacctic Acid IOIN
N aphthalcnccarboxylic Acid
Naphthalcncdicarboxylic Acid
Octahydroindcnone
Petroleum Product N N
Tctrahydromethylnapbthalcne 3/N
Tctrahydronaphthalcoe 3/N
Tctrahydrothiophcnedioxidc
Tctramethylbcnzcne (2 isomers) 7/N
Tctramethylbenzenc 3/N
Trimcthylbenzoic Acid (3 isomers) 60/N
Trimethylbenzoic Acid, Methyl Eater 3/N
Trimcthylbcnzoic Acid (2 isomers) 20/N
Trimethylpbcnol
4 Unidentified Compounds
7 Unidentified Compounds 100/
!filI!2:
J Estimated value.
N Presumptive evidence of presence of material (tentative identification).
U Material waa analyzed for but not detected. Value is quantitation limit.
Not detected in the sample.
TABLEB-3
(continued)
20/N
18
20/N
3.71
2.6/
20/N
20
IOIN
9/N
3/N
N
4/N
61N
40/N
21N
501
60/N
IOU IOU
IOU IOU
IOU IOU
IOU 171
40/N
N
200/N
!!!!!!I ~ == == liiiiiil
IOU IOU IOU IOU
IOU IOU IOU IOU
IOU IOU IOU IOU
IOOU IOU IOU IOU
N
400/N
11111111111 iiiiiil iiii iiiil l!!!!!!!!!!!I l!!!!!l!!!!I
Pesdcitk/PCB Compounds
Purg,eabk Orz..anic Comt!,ounds (µg/l)
Benzene 4.2 7.7
Ethyl Benzene 4.51 8.8
Ethyl Ether 701N 2001N
.Ethylmethylbenzene (2 isomcn) 20JN
Mcthoxymcthylpropane
0-Xylenc 9.4 16
Tert-Butyl Alcohol
Tctrahydrothiophcne
Toluene 5.0U I.II
Trimcthylbcnzenc (2 isomers) 20JN
Trimethylbcnzenc (3 isomers) 50JN
Trimethylbcnzenc
(M-and/or P-)Xylcnc 3.7) 9.0
llilI!l§:
I Estimated value.
N Presumptive evidence of presence of material (tentative identification).
U Material was analyzed for but not detected. Value is quantitation limit.
Not detected in the sample.
TABLEB-3
(continued)
7.8
8.7
2001N
101N
17
I.II
501N
8.9
I.OU
5.0U
5.0U
5.0U
5.0U
~
74
28
lOOJN
7.81
401N
30JN
25U
30JN
25U
110 I.OU I.OU I.OU
371 5.0U 5.0U 5.0U
200JN
27) 5.0U 5.0U 5.0U
5.91 5.0U 5.0U 5.0U
60JN
39) 5.0U 5.0U 5.0U
I
I
I
g
n
n
D
D APPENDIXC
D COST ESTIMATES
D
m
m
m
m
m
~
I
D NHANFS09. 022
in
g
u
Table Numba: B-1 PRESENT WOR1H COST
D Alternative No.: 1
No Action
D
Site Name: New Hanover County Airport Project ¥-naaer: TRC Site Location: Wihnington, North Carolina Date, 0Bn4/92
ANNUAL UNIT PRICE TITTAL ANNUAJ OPERATION PRP.SENT ITEM DESCRIPTION UNITS QUANTIT, DOILARS COST, DOT.TAR! TIME, YEARS WOR1H
LONG-TERM GROUNDWATER MONITORING
Penonnel hou, 24 $50 $1,200 30 $11~12 Supplies eacl, 12 $250 $3,000 30 $28,281 Annual Well Sampling & sample 6 $500 $3,000 30 $28,281
Laboraiory Testing (6 Weil,)
SUBTOTAL $7,200 $67,874
CONTINGENCY -Cost Based on 10% of Subtotal $720 $6,787
a TOTAL $7,920 $74,661
ALTI.WKl
I
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I
D
u Tablo Numbor: .. , PRESENT WORTH COST
AltmIWivo No.: 2
D Vankal Burlm
Sito Nuno: Now Hmovw County Airport Projod Manai=: TilC
Sit,:, Locatlcc: W~ Neri. Carolina D&tll: 08/14J}l
D UNITPRJCB TOTALOOST
rrBM DBSCRlPTION UNITS QUANlTrY OO!ll.R.S OO!ll.R.S
D FENCING ft 2,000 S20 $40,000
MOBU.IZA.TION
Trampart Bquipzmm: A Slaff .... I $15,000 $15,000
D
Temporary P,cllha ""' I Sl0,000 $10,000
CAPPING
Sim Prcplrlliw -,., $3,000 $10,200 Cap Material • 40 ml Linar ... 150,000 0.4.5 $67,lOO
E c.p """""""' -,., $4,400 $14,960
Covet M.w:rial, &cement. " 1,075 .. $8,600 &----" 530 .. $4,240
CJradmamd~ -, .• 57,000 $23,800 SoodmdMwcl, -,., $2,000 $6,800
°""""""""""' ... 150,000 0.17 $23,lOO Pila Pabrk ... 150,000 0.24 $3~000 Boddma Mc,rlal • Smd & Cmvcl " 1075 S7 S7~1'l
Dctcntioa Pm4 .... I $10,000 $10,000
Sur£ace Rimof!Co1loetlon Sylltllm .... I $30,000 $30,000
hutallalian of Monhor Well, .... ' $2,500 S7~00
VERTICAL BARRIBR
Bxavation " 5,300 110 $53,000
Cemc:m-Bcmanho Slurry ., 48,000 S4 $192,000
Monitor Woll lmtallatlm wcll 4 $3,500 $14,000
BQUIPMENI' & MATilRlAU
I Hoalth & Sd,ty Bqllipiri,:,iit .... I $5,000 $5,000
AIR QUALITY MONlTORINO _, 48 $200 $9,600
MJSCEIJ.ANBOUS BQIJIPMHNT & SUPPUH lumpJUtn I SI0,000 $10,000
I Subtotal· Capital Cm s«n.m
Cmtnc1or'1 Fon ( I~ or Capital Coll) $90,184
I Lea;al Pee■, l...k::c:mca & Pt:rmh,( 10'i\ of Capital Coll) $60,123
Engineering & Administn.tiY11 ( 15% of Capital Colt) $90,184
n ··-$841,715
Cwtingcncy ( lO'i\ o!Si.btw.l) $84,172
I TOTAL CONS1RUCTTON COST $925,887
PRESENT WORTI-1 O&M COST $161,766
TOTAL PRBSBNT WORnl COST $1,087,652
I ALTI.WKl
B
I
D
D Tablo Nmnbar: 8-2 (Cmulnuod) OPBRATION & MAIN'IBNANCll. COSTS
AltllmUivo No.: 2 Ptriodo!Monitorina: 30~
Vortkal Bamtlt DbeamtR&m!IO"lo
D Project Manqcr: TRC
SIIDNmm: Now Hmovor CWDly Airport Dam: 08/14192
Sllzi Location: Wilmm&ton, Nath Carolina
E ANNUAL UNITPRICII irorALANNUAL OPBRATION PRESl!NT
rrBM DBSCRIPTION UNITS QUA>mTY DOLLARS msT,DOLU.RS 11MB, Yl!AR5 WOR1H
CAP MAINTBNANCB AND REPAIR --,. "' $4~00 30 $4S,~9 '"""" """ 12 $500 $6,000 30 s.,6,561
LONO-TBRM GROUNDWATER MONITORING --16 "' $800 30 17,542 '"""" """ 8 5230 $~000 30 $18,854
AmlD.11 Woll Saq,lln, & ...... • ubcntttyTcatma; (4 Wolb)
ssoo szooo 30 $18,854
SUBTOTAL $15,(i()() $147,060
CONTINGENCY· Con Bucid m 1~ of Subtotal $1,560 $14,706
I TOTAL $17,160 $161,766
ALTl.WJU
I
D
I
I
I
I
I
I
I
I
I
0
D Tatu Number: .. , PRBSBNT WORTI{ COST
Allmtlativo No.:]
D Allmtl&tive: Cm.uidwlll:lr Bx1r1etim md Pb)'llal TrN!mCIDt
CAh Slripptni) wbh DIK.lwp to P01W
SilDNmm: New Ha.noYor County Ahpcrl: Silo Project Manapr: TRC
Sillll.«.&tia:i: Wilmlnpm,Nonb.C.,ollna DD: 08/14/92
E UNITPRICB TOTALCX)ST
fI1!M DESCRIPTION UNITS QUANITIY DOLLARS DOLLARS
PBNCINO • 1,800 S20 $36,000
MOBll.tl.ATION
Tl"&?llpmt Bqupnt ,I; Staff .... I $15,000 $15,000
Tcmpozuy Facllita """ I $10,000 S10,000
GROUNDWATER BX'TRACTION
Sim Pl'cpanw:a -,., $3,000 Sl.500
&lnetlonWe.1.1 woll 3 $3,500 S10,500
Pipca, V1J:....,a, & P'lltlnp • 400 S20 $8,000
WATER TRHATMENT FACILITY
Silo Prc,paratia:i •= ,., $3,00) $1,500 ........ " '" '" $3,750
I WATER 1'RBATMENTPROCliSS UNITS
Bqu,Jballon Tllllk .... • Sl!i,000 $60,000
PrwoatmDm PM:lllty lump tum I $100,000 $100,000
D
Air Slrippma Unh lump tum I $35,000 $3!5,000
Trm!orPumpt ""' 4 $4,500 $18,000
Plpina, ValV011, &. Appurrlmmcm lump nm I $10,000 S10,000
Fi11mPrea .... I $10,000 SI0,000
lmtl'1luicm and Control, lumpnm I $15,000 SU,000
n --lwnptum I S10,000 $10,000
Bqwpnmlt lmtallatiaD. lump tum I $49,875 $49,87!1
DISOIAROB TO P01W
Volum,, Pco 748 pl 12,900 $2.01 S26,1150
I Smoho,g, lump tum I $10,000 $10,000
MISCE..LANBOUS BQUIPMRNT, ,I; sum.,m 1,mp= I 520,000 $20,000
btal.latkm of Maniu:ir Wela .... ' $2,500 S7'00
I ANALITlCALLABORATORY
Tcstina fir Prw.cu Vcriflcalia:i ...... 144 S,00 $7~000
Subtcnl • Capltal Ca.t $529,67!1
I C«itraaor'1Peo( 15'ofCapltalCOlt) $79,451
Legal Poca, u~ .t Pamil.( 10':II of Capital COit) S,'967
I BnJin,::ering & A.dminl,tratlw ( IS~ of Capital Co.i ) $79,451
'""""" $741,S.W
I Cauinac:ncy ( 101' of Subtotal ) S74,1S4
TOTAL CONSTRUCTION COST $815,699
PRESHNI' WORTH O&M COST Sl,074,184
I TOT AL PRESHNT WORTI-l COST SI,889,883
ALT4,WKI
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0
u T.-blo Number: 9.3 (Cantb:iu.od) OPERATION & MAINIBNANCE COSTS Alamtiw No.: 3 lwiodofMmil:.orin&:30yoart Altmmtivo: Orawiw&lm lb.tractioo. and Pbyaiw Treatm;nt Dllcaml: Ra!D: I O'l,
E (Air Slripplna) wl!h Diaclarp to P01W P,oJo«-TRC SilD Nu:rm: New Hatmw Cowuy Alzpat SilD Dam: 08/14Hl Sim L«atkn: Wi1mlD&tm, Nri Carolina
E ANNUAL UNJTPRICB TOTALANNUAl OPBRATIO? PRBSl!NT rrRM DESCRIPTION UNITS QUANTITY DO!ll.RS COST, 001.U.RS TlMB, YJWe WOR1H
OROUNDWATBR 'IllBATMENT SYSTBM
m MONITORING (1' aprn)
HNBROY(l5HP) twh, "'" S0.07 $6,859 • $21,742
MAINTBNANCE & REPAIR _,. 12 $3,00) S3~000 • $114,115 I OPBRATINO LABOR (24 bOlln: per day) •= 2,920 $.50 $146,000 4 $462,800
'
MISClilJ...ANEOUS OiBMICALS _,. 12 $500 $6,000 • $19,019
m SHORT•TBRM GROUNDWATER MONITORil<lO -•= 288 $.50 $14,400 • $45,646 S,ppilo, '"" ,, '"° S6!)00 • $19,019 Wccldy Well SampUna & umplo 144 1.500 $72,000 • $228,130 • Labaatay Tostma (6 Wolla)
LONO-TI!RM GROUNDWATER MONITORING -h= ,, $.50 11,200 ,. S10,993 S,ppilo, """ 12 '"° $3,000 ,. $77,483 I Ammal Well SamplfDa & ,_., ' $.500 $3,000 ,. $27,483 Lab<ratay TOl1hig (6 Woll.I)
SUBTOTAL $294,459 $976,531 I CONTINOBNCY. CmBuodon lO'ilo orS11btotal $29,446 $97,653
TOTAL $32.3,90, $1,074,184
I ALT4.WJCI
D
D
I
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I
I
• •
I
D Tatu Niunbn: ... PRESENT WORlH COST
AID:itmttve No.: 4
AllmlW!vc: Oroundwatm Bxlnetlon IDd Ph)'l1cal,/Ch:,mlcal Tn,almCIIlt
(Circmium Raductkm, Metal, ~tb:l, and Air
D Strlppini) wl!b. Dildwp Via Spn.y 1nipticm
SilDNamo: N-Hm:M:r Cmllt)' Ahpat Sill:I Projc,c:tMamacr.TRC
Sita Location: W~ North Carolina Da!D: 08/14f}l
UNITPRICB TOTALOOST
I ITEM DBSCRJPTION UNITS QUANIIT DOll.ARS DOll.ARS
Fl!NCINO ft 3,000 $20 $60,000
MOBll.l'l.ATION
Tramp,rc BquipmDm & swr ..,. I $25,000 $25,000
TemporuyPKlllda ..,. I SU,000 $15,000
OROUNDWATBRBXTRACTION
SilDPff;pvatla:I -I $3,000 $3,000
Extraction Well ..u 3 $3,500 $10,.SOO
Pipes, VUv,:,1, &. P1tt1op ft 400 S20 $8,000
WATER TRRATMBNT FAat.rrY
s "" --., $3,000 $1,500 ..,.,,. ... "' 250 m $3,750
Troatmcnt Paclllry Hou.q lump ram I $10,000 $10,000
WATER lRBATMBNrPROCESS UNITS
BqwiulloD Timk ..,. 4 $10,000 $40,000
MctabRi:imovalFacillticl ·--I $150,000 $150,000
Air Stripplna Uull "--I $35,000 $35,000
Trlilfc:rPum~ ""' 4 $2,500 $10,000
Plpina. ValVCII, & AppurtenaDcm lump ram I $15,000 Sl!i,000 Pila,_ ""' I $10,000 Sl0,000
lnstnimcmb: &Dd c.cm.!IW ·--I $20,000 $20,000 --·--I $15,000 $15,000
Equipm=i lmtall.aticm. lump ram I $64,375 $64,375
DlSOlAROB VlA SPRAY IRRIGATION
Pmnp, P1p1na, Sp-lnklcr &ad. lump nm I $20,000 51.0,000
StcnplTIIIW ..,. 4 Sl!i,000 $60,000
"""""""' Jump1um I $8,750 $8,750
MISCBI.J..ANBOUS EQUIPMENT & SUPPUBS ·--I $20,000 $20,000
imtallatlaoofMonilOl"Wclb '""' 3 $2,500 $7,500
ANALYTICAL LABORATORY
I Tcating for Pro<:e.. Vcrificatlmi ...... 144 $500 $72,000
Subtcw. Capital Cost $684,375
Cmtnctor'1 Peo ( 15'\ of Capital Cost) S102,656
I Leaallw-, Ucomoa & Permit, ( 1~ of Capital Coll) $68,438
~ma & Adrniru.tnativv ( 15' o! Capital Cost) $102,656
I S""""1 S958,I25
Cwtingcncy ( lO'J, or Si.btotal ) S95,813
TOTAL CONSlRUCTION COST SI,053,938 n PRBSBN'T WORTII O&M COST Sl,265,217
TOT AL PRBSBN'T WORTil COST S2,3I9,I54
ALT4,WJCI I
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D
D
D
I
Tttio Niu:nbor. B_. (Cmtil'Juod) OPERATION & MAlN'IBNANCE COSTS Al~No.:4 Period o! Momtarina: 30 )'Olnl AllmDllM:i: Chamdwl.lZII' &tractioii and Pb)'lblJCbcmkal TM&tmem Dbcwmllam:10',\
(~ Rodw::tioo, Matab Proc:lpltatimi, IIDd Air Projoc:t Manapr. lllC
Stripp!Da) with Dlacharp Via Spny lrrlption Dam: 08/14/Yl SitDNanm: Now~ Couniy Airport Silo
Silo Locat!iu: WiJ.m.ln&too, Ninh Cuollna
D ANNUAL UNITPRICB fl'OTAL ANNUAL bPBRATION PRBSBNT rrBM DBSCRIPTlON UNITS QUANim DOLLARS ICOST, 001.LARS iThm,YBARS WORnl
GROUNDWATER TRBATMBNT SYSTEM MONTI'ORINO
(15apm)
BNBROY(20HP) ,..,. 130,650 $-0.1)7 SSl,146 4 $28,990
MAINIENANCll & REPAIR ...... 12 $4,000 $48,000 • $152,154
OPllRATINO LABOR (2.4 ~ poz-day) bo,u i920 '" $146,000 4 $462,800
PLOCCUU.N'TS/COAOULANTS _., 12 S.000 $24,000 4 f(l~<m
SUJDOB DISPOSAL drum (55-pl) 33 !SOO $16,500 4 ssi'°'
I MlSCEUANBOUS OiE.\t:ICAI.S ...... 12 ssoo $6,000 4 $151,019
SHORT-TERM OROUNDWATBRMONITOIIDW -·-288 150 $14,400 • $45,646 S!lpplict ""' 24 $250 $6,000 4 $19,019 Weekly Wall Samplin1 & -· 144 S,00 "7iooo 4 $218,230 l..aba-atay TostJna (6 Wclb)
LONO-TERM OROUNDWATBR MONITOR.nm -bo,u 24 $50 $1,200 ,., $10,993 ,,.,,.,., ""' 12 1250 $3,000 ,.. SZ7,483 Amm.a1 Well SampliDa; & -' !SOO $3,000 ,. $27,483 Labirmry Tertina (6 Wclbi)
I SUBTOTAL $349,246 Sl,1.50,197
CONTINOBNCY. Cost Buodc.i lO'i\ o£Subcotal $34,925 $115,020
D TOTAL $384,170 $1,265,217
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D Tatu. Numbcir: .. , PRESBNT WOKlli COST
AllzlnlaUYo No.: !I
Alll:lmali.vo: Chwndwat=" &traalon ml Piiytkll/CIDmk:al. T~o:Pent
D (Cbromhim Rocmcdcc md Mlliab Proclpitatia::i) wbb
Dwdwp to SllnKO Wat=
SltoNamo: N~w 1-wKr.a Cwnty AbpM Sito Projoet Manapr. TRC
Site Locatim1: Wilmingta:i, N!Wi Carcl.ina Data: C):1/14/92
E UNITPRICB TOTALOJST
ITEM DESCRIPTION UNITS QUANTITY DOLLARS D011>.RS
PBNCINO • aooo S20 $40,000
D MOBil.lZATION
TfllllpM Bquipmi,nt & Staff """ I Sl!l,000 Sl!l,000
Tomponry PacllltJc. ""' I $10,000 $10,000
GROUNDWATBRHXJRACl1ON & RRINJBCTlON
SltoPrcparuimi •= I $3,000 $3,000
Exlr'IC:tkm Well .... 3 $3,500 $10,500
Pqm, ValYi:11, & Plttinp • 400 S20 $8,000
WATBR TRBATMRNT FACILITY
Sito Propatatloo -= o., $3,000 $1,500 ......... " 250 115 SJ,750
WATBR 1RRA1MBNT PROCl!SS UNITS
Bquallwiou Timk ""' • $15,000 $60,000
MDtaltRomovalP&eillty ·--I $150,000 $150,000
Bquipmmlthuitall.tiw ·--I $66,000 $66,000
TrlWCZ" l'llmpi '"" • $2,500 $10,000
Pipin,&, Valves, ct AppUJ1mW1cc1 lump1JU1D. I $10,000 $10,000
PiltmPrca ""' I $10,000 $10,000
lnrtt slion imd Cwtrob ·--I $15,000 Sl!i,000 -..... ·--I $10,000 $10,000
Bqu.lpm::nt lmtallaticm ·--I $69,625 $69,625
DISCHARGE TO SURPACll WATBR
Pipin1 If 4,000 125 $100,000
Tnmfc:rPump ""' I $3,500 $3,500
1nmlhtim, lump tum I $40,000 $40,000
MlSCll.J.ANEOUS BQUIPMBNT & SUPPUBS ·--I $20,000 $20,000
lnnall&tloo of Monitor Woll, """ 3 $2,500 $7~00
ANALYTICAL LABORATORY
T"1:mi far Pnx:eu Vcrlfiwi!Kl ..... , 144 $500 17SOOO
Subtta.l • Cq,ltal Cost $735,375
Cwtnc:tor'1 Pea ( 15'1-of Capital Coa) $110,306
legal Fcc1, Licon.c:1 & Permits ( 1or.. of Capital Cost) $73,538
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&iu-rina & Administrative ( 15'1-of Capllll Coa) $110,306
'"""" SI,029.S25
Cmtingenc:y ( 1~ o!Sllbtotal) $1()2,953
I TOTAL CONSTilUCTION COST $1,132,478
PRBSBN'T WOKJll O&M COST Sl,194,481
I TOT AL PRBSBN'T WORTII COST $2,326,958
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D Table N11Z11bor: B-5 (Ccmtlnuod) OPERATION A MAINmNANCi COSTS
Allmmlivt1No.:5 Pwiod olMonl.torio,: 30 )'Call
Altllmatfvc: OrDWldwatm &traetlo:n md Pbytlc:al/ClJcmleal Tniatmmt D~iwD:10',\
(Clromhmi Rodll.ctko 111d Mawa Proclpiw1oo) WI.lb Projoc:IMamacr:TRC
Dlaclmaa toSurfaeo Watm Data: 08/14m
SilDNum: Now lWKMlr County Abpcn Sito
S1111 i.oc.tm: Wilm.lnatm, NCl'tb Cardin,.
ANNUAL UNIT PRJC!! TOTAL ANNUAi OPBRATim PRBSBNT ITBM DBSCRIP110N UNITS QUANrITY DOLLARS COST, D01.UJtS TIMB,,YRAR WOR111
GROUNDWATER TIIBATMBNT SYSTEM MONITORING
(UIPUI)
BNRROY(15HP) kwlu "'" $0,07 $6,859 • Sll,742
I MAINJBNANCB & REPAIR _,. 12 $3,000 $36,000 • $114,115
OPBRATINO LABOR (2.4 boun per day) •= 2,020 $50 $146,00J 4 $462,800
I PLOCCULAm'SJC()AOULANTS ="' 12 12,000 $24,000 4 t76,rm
SWOOB DISPOSAL drum (S5-aal) 33 $500 $16,500 4 $52,303
SHORT·Tl!RM GROUNDWATER MONITORING
I -•= "' $50 S14,400 • $45,646
Sllpp.im ""' 24 1250 $6,000 4 S19,019 Wcckly Woll S1unplln1 & -144 $500 172,000 4 1228,230
~tcry Tcnina: (6 Woll1)
I LONO-TBRM OROUNDWATBR MONrfORINO --24 $50 Sl,200 ,. S10,993
'""'"" '"" 12 '"' $3,000 ,. $27,483
Anmw Woll SampliDa; .t -6 $500 $3,000 ,. SZ7,483
l..abcr.iay Tcstin& (6 Wclh)
I SUBTOTAL $328,959 $1,085,891
I CONTINGENCY· CM Sued ai. lO'll, of Subtotal $32,896 ,1108,589
NfAL $361,855 $1,194,481
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