United States Office of
Environmental Protection Emergency and
Agency Remedial Response
• EPA/ROD/R03-88/048
April 1988
oEPA Superfund
Record of Decision:
Delaware Sand & Gravel, DE
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50272-101
REPORT DOCUMENTATION 11. REPORT NO.
PAGE . . EPA/ROD/R03-88/048
I ~
3. RedplenC'8 Accesalon No.
4. TIle Ind SWHe
SUPERFUND RECORD OF DECISION
Delaware Sand & Gravel, DE
First Remedial Action
7. AuIhor(a)
~ Report 08.
04/22/88
8.
8. P8rf0nnlng Ofganlzatlon Rept. No.
O. Perfonnlng Ofgelnlzatlon N8In8 and Add-
10. Profec1/Ta8k/WOt1t Unit No.
11. ConIr8ct(C) or Gtant(G) No.
(C)
(0)
1~ ~ng Organiutlon N8In8 and AdchM
U.S. Environmental Protection
401 M Street, S.W.
Washington, D.C. 20460
13. Type 01 R8pOI1 . Period Covered
Agency
800/000
14.
1~ Supplem8nWy No..
18. Allene! (Umlt: 200 _rda)
The Delaware Sand & Gravel (DS&G) site is a 27-acre inactive industrial waste landfill
located in .New Castle County, Delaware. It is bordered by Army Creek to the west, Army
Creek and wetlands to the north, residential and business facilities to the east, and
an abandoned sand and gravel quarry to the south. Also to the west of the site
directly across Army Creek is the Army Creek Landfill NPL site. Residences are located
approximately 30 feet from the landfill and a residential development is located
approximately 0.5 miles south and southwest of the site. Underlying the landfill is
the Potomac Aquifer, which is accessed about 1.25 miles south of the site and is used
as a public water source. The DS&G site consists of four disposal areas, referred to
as the Drum Disposal, Inert Disposal, Ridge, and Grantham South areas. Between 1968
and 1976 the site accepted household and construction wastes, and approximately 7,000
drums containing liquids and sludges from perfume, plastics, paint, and petroleum
refining processes. In 1971, investigations revealed ground water contamination
emanating from the Army Creek and DS&G landfills. In 1976, the Delaware Department of
Natural Resources and Environmental Control .issued an enforcement action requiring DS&G
to discontinue disposal activities. A ground water recovery system was installed to
prevent contaminated water from reaching the nearby private well field, which continues
t6 operate. Investigations were conducted to characterize the source and extent of
17. Doc:ument AnaJ)'8I8 L DMaipeora
Record of Decision - Delaware Sand & Gravel, DE
First Remedial Action
Contaminated Media: gw, soil
Key Contaminants: VOCs (benzene, toluene, xylenes),
metals (chromium, lead)
organics (PCBs, PAH, phenols),
b. Id8t:Itlf\erLlOpen-Ended T8m18
c. COSA 11 FIeIdIGroup
t8. A vallabllty Statement
1.. Se
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EPA ROD/R03-88/048
Delaware Sand & Gravel, DE
First Remedial Action
Abstract (Continued)
contamination from both sites/ and in 1984 EPA initialized an emergency removal action
at; the DS&G site to remove approximately 600 drums from the Drum Disposal area. An
estimated 535,000 yd3 of waste material are located onsite. Wastes identified in the
Drum Disposal area include subsurface soil and debris contaminated with PCBs, organic
liquids, and inorganic solids. The Drum Disposal area is believed to be the major
source of organic ground water contamination. The Ridge area consists of contaminated
surficial soil, and drums, storage tanks and debris scattered on the surface. The
Inert Disposal area contains various domestic waste, cars, trucks and storage tanks
scattered on the surface. The Grantham South area is believed to contain surficial
inert waste as well as deposited chemical wastes. Two hot spots of organic
contamination were identified in this area. The primary contaminants of concern
affecting the soil and ground water are VOCs including benzene, toluene, and xylenes,
other organics including PCBs, PAHs, and phenols, and metals including chromium and
lead.
The selected remedial action for this site includes excavating and incinerating onsite
approximately 36,000 tons of contaminated soil and wastes from the Drum Disposal and
Ridge areas, with on- or offsite disposal of residual ash and grading and revegetating
excavated areas; removal and offsite disposal of all surface debris material from the
Inert area, followed by capping; constructing a RCRA cap over the Grantham South area;
pumping and treating ground water with discharge to Army Creek; and ground water
monitoring. The estimated present worth cost for this remedial action is $24,944,000.
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Record of Decision
Declaration
Site Name. Location and DescriDtion
Delaware Sand and Gravel Site
Grantham Lane
New Castle, DE
Statement of Basis and Puroose
This decision document presents the selected remedial action for the Delaware
Sand and Gravel Site developed in accordance with the Comprehensive
Environmental Response, Compensation, and Liability Act of 1980, as amended by
the Superfund Amendments and Reauthorization Act of 1986, and to the greatest
extent practicable is not inconsistent with the National Oil and Hazardous
Substances Pollution Contingency Plan of 1985 (40 C.F.R. Part 300).
This decision is based upon the contents of the Administrative Record for the
Delaware Sand and Gravel Site.
The State of Delaware developed this decision document in conjunction with EPA
and therefore concurs with the selected remedy.
DescriDtion of the Remedv
The Remedy selected addresses the sources of contamination by remediation of
on-site wastes and contaminated soils as well as addressing remediation of the
groundwater contamination plume.
The major components of the selected remedy include:
Excavate wastes and contaminated soil from
Area and treat the wastes and contaminated
to alleviate the direct contact threat and
major contamination sources on the site.
the Drum Disposal and Ridge
soil by on-site incineration
leachate generation from the
Capping of the Grantham South Area in order to alleviate direct contact
threat and potential leachate generation.
Debris Removal and Capping the Inert Disposal Area to alleviate
potential direct contact threat and to meet State of Delaware Solid Waste
Regulations.
Continue recovery of contaminated groundwater to eliminate potential
groundwater ingestion risk.
Implementation of treatment of recovered contaminated groundwater prior
to discharge to Army Creek.
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Declaration
The selected remedy is protective of human health and environment, attains
Federal and State requirements that are applicable or relevant and
appropriate, and is cost-effective. This remedy satisfies the preference for
treatment that" reduces toxicity, mobility or volume as a principal element.
Finally, it is determined that this remedy utilized permanent solutions and
alternative treatment technology to the maximum extent practicable.
Because this remedy will result in hazardous substances remaining on-site, a
review will be conducted within five years after commencement of remedial
action to ensure that the remedy continues to provide adequate protection of
human health and the environment.
Phillip G. Retallick
Director of the Division of Air and
Waste Management
Dept. of Natural Resources and
Environmental Control' .
State of Delaware
a,t~,:1~/fir
I£f!ff=
jf:ames M. Seif
egional Administrator
EPA Region III
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OFFICE OF THE
DIRECTOR
STATE OF DELAWARE
DEPARTMENT OF NATURAL RESOURCES
8: ENVIRONMENTAL CONTROL
DIVISION OF AIR & WASTE MANAGEMENT
89 KINGS HIGHWAY
P,O, Box 1401
DoVER, DELAWARE 19903
TELEPHONE: (302) 736 - 4765
APf\ ::.1 'IS;>:)
Mr. James M. Seif
Regional Administrator
U.S. EPA Region III
841 Chestnut Street
Philadelphia, PA 19114
Subject:
tion of the ROD - Delaware Sand & Gravel
er
As per Cooperative Agreement #V-003299-01-7, the Delaware Department of
Natural Resources and Environmental Control (DNREC), CERCLA Management Branch
has completed the Record of Decision for the Delaware Sand & Gravel site.
Through the coordinated efforts of DNREC and EPA, the Department feels' an
appropriate remedy for the site has been selected. By signature of the
"ec1aration of the ROD, DNREC has formally expressed its support of the
selected remedy.
In order to finalize the Delaware Sand & Gravel ROD, we are now requesting
EPA's signature on the Declaration of the ROD.
(~J
Phillip G.
Director
Retallick
PGR:NC/mff
NC2100.2
cc:
G. A. Molchan
J. J. Hardman
N. V. Raman
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I.
II.
. III.
IV.
V.
VI.
VII.
TABLE OF CONTENTS
. FOR
DECISION SUKMAB.Y
SITE NAME, LOCATION AND DESCRIPTION
SITE HISTORY
ENFORCEMENT HISTORY
SITE CHARACTERISTICS
A. GEOLOGY/HYDROLOGY
B. NATURE OF WASTES
- Drum Disposal, Ridge Area, Inert Area, Grantham South
C. EXTENT OF CONTAMINATION
- Surficial Soils
- Formation Soils
- Surface Water and Stream Sediments
- Groundwater
- Air
D. SUMMARY OF SITE RISKS
COMMUNITY RELATIONS HISTORY
REMEDIAL ALTERNATIVE OBJECTIVES
REMEDIAL ALTERNATIVE EVALUATION
A. SOURCE CONTROL
B. GROUNDWATER PLUME MANAGEMENT
VIII. DOCUMENTATION OF SIGNIFICANT CHANGES
IX.
SELECTED REMEDIAL ALTERNATIVE
A. DESCRIPTION AND PERFORMANCE GOALS
B. STATUTORY DETERMINATIONS
APPENDIX A. - SUMMARY OF ANALYTICAL DATA
APPENDIX B. - RESPONSIVENESS SUMMARY
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Delaware Sand & Gravel
Record of Decision
Decision Summary
I.
SITE NAME. LOCATION AND DESCRIPTION
The Delaware Sand and Gravel Landfill (DS&G) is an inactive industrial waste
landfill located in New Castle County, Delaware.
The site is approximately
two miles southwest of the City of New Castle on Grantham Lane, west of Route
9, and less than one mile east of the intersections of Routes 13 and 40 as
shown in Figure 1.1
The property considered as the Delaware Sand and Gravel Landfill is
approximately 27 acres in size.
Wastes are located in four smaller areas on
the property.
The smaller areas are referred to as the Drum Disposal, Inert
Disposal, Ridge, and Grantham South areas (Figure 1.2)
Wastes disposed on
site include household and construction waste and approximately 7,000 drums
containing industrial liquids and sludges.
The area surrounding the site includes Army Creek (a tributary to the Delaware
River) to the west, Army Creek and wetland area to tqe north, residential and
business facilities to the east, and an abandoned sand a~d gravel quarry to
the south.
Also to the west of the site, directly across Army Creek, is the
Army Creek Landfill, an inactive municipal landfill currently on the National
Priorities List.
The site is not located in Army Creek's floodplain.
Also it has been
determined no wetlands of significance exist on the site.
Wetlands do exist
in peripheral areas but will not be impa~ted by remedial action on-site.
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The closest residences to the site are located approximately 30 ft. from the
landfill on Grantham Lane.
Also Llangollen Estates, a residential development
is located approximately 1/2 mile south and southwest of the site.
Underlying the site are two water bearing formations.
The uppermost is the
Columbia water table aquifer which is practically nonexistent at the site.
Under the landfill the aquifer of concern is the Potomac Aquifer located
approximately 30 ft. below land surface.
Prior to 1952, groundwater flow in the Potomac aquifer was predominantly to
the west.
Since 1952, groundwater has moved within the Po~omac Aquifer to the
southeast, east, south, and southwest due to various water supply and recovery
well pumpage scenerios.
At present the flow is predominantly in the westerly direction toward the
recovery wells.
The Potomac aquifer is used approximately 1 1/4 miles south of the site as a
public water source by Artesian Yater Company.
II.
SITE HISTORY
The Delaware Sand and Gravel Landfill was formerly operated as a sand and
gravel quarry.
Yaste disposal began on a permitted b~sis in 1968 and
continued until 1976 when the DNREC issued enforcement action for improper
disposal operation.
Investigations in the area began as early as 1971, when a residential well
southwest of the Army Creek Landfill developed water quality problems.
Early investigations revealed that leachate most likely originating from the
Army Creek Landfill and Delaware Sand and Gravel Landfill was contaminating
local aquifers.
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LOCATIO! ~
DELAWAIE SARI) ARD GlAVEL SITE
ImEDIAL IRVESTIGATIOR
CERCLA 85-1
l1pre 1.1
Location ..p for the Dalavara Sand and Graval L8Ddf111
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OCLAWARE SAMO a WUVEL LANDFILL
AREAS OF HASTE DBPOSAL
Figure 1.2: Areas of waste disposal In the DS4C
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In response to the contamination problem from the Army Creek landfill, New
Castle County installed a groundwater recovery system designed to prevent the
movement of contaminants towards the Artesian Water Company wellfield by
maintaining a groundwater divide.
The groundwater recovery system has
operated for 12 years and is operating today successfully capturing
groundwater contamination from Delaware Sand and Gravel.
Investigations characterizing the source of contamination and extent of
contamination continued for both the Delaware Sand and Gravel and Army Creek
Landfill.
In the spring of 1984, EPA/DNREC performed an emergency removal.
After removal of approximately 600 drums from the surface of the Drum Disposal
Area, the removal action was discontinued and the area was covered and
revegetated.
A Remedial Investigation (RI) and Feasibility Study (FS) centering on Delaware
Sand and Gravel (DS & G) began in the fall of 1984.
The RI was completed in
December of 1987 and the FS in February of 1988.
III. ENFORCEHE~~ HISTORY
In 1975 the DNREC began enforcement action against the Delaware Sand & Gravel
Company, which owned and operated the landfill, for violations of the State
Solid Waste Permit.
Specific violations include improper operating procedures
such as poor cover and compaction.
The enforcement action was initiated as
two civil suits which are pending litigation.
Nineteen Potentially Responsible Parties (PRP's) were identified in the June
22, 1985, EPA Final Potentially Responsible Party Report.
The PRP's were con-
tacted by telephone prior to the March 16, 1988, RI/FS public meeting.
The
PRP's were also sent CERCLA 106 letters on March 22, 1988, pursuant to
106
of the Comprehensive Environmental Response, Compensation, and Liability Act,
42.USC
9601.
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In order to allow the PRP's reasonable opportunity to comment and provide
information, the public comment period was extended from March 26, 1988, to
April 18, 1988.
IV.
SITE CHARACTERISTICS
A.
GEOLOGYIHYDROLOGY
Geologically, DS&G is within the Atlantic Coastal Plain physiographic
province.
The coastal plain is a stratified, seaward thic~~ening wedge of
unconsolidated and semi-consolidated sands, silts, clays, and gravels
deposited atop a seaward sloping complex of crystalline basement rock.
In the
Army Creek area, the Quaternary (Pleistocene) Columbia Formation occurs as a
veneer over the seaward dipping Cretaceous-aged Potomac Formation.
Quaternary
(Recent) alluvial deposits occupy current streams and tidal marshes.
Depths
to bedrock range from 400 to 650 feet below land surface.
The contact betwe~n the Quaternary (Columbia) sediments and the Potomac
Formation is an erosional and angular unconformity.
Figure 1.3 is a contour
map depicting the base elevation of the Columbia Formation which is also the
top of the Potomac Formation.
Usually, a dense red clay marks this contact.
This clay (the Uppermost Potomac confining clay) is believed to be absent in
two areas:
one, at the subcropjrecharge zone for the Upper Potomac Hydrologic
Zone about one mile northwest of DS&G; and two, between Army Creek Landfill
and DS&G as a small hole or window as shown in Figure 1.4.
This window is the likely
pathway for contaminants entering the Upper Potomac Hydrologic Zone.
The Quaternary sediments comprise the shallow water-table aquifer which is
essentially dewatered at DS&G.
The Potomac Formation has been interpreted to
include three artesian aquifers.
The uppermost Potomac aquifer, called the
Upper Potomac Hydrologic Zone (UPHZ), is the aquifer of concern in this
investigation, especially the top portion which is referred to as the upper
Upper Potomac.
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DElAWARE ~D . GRA\n
ElEVAlION CJF 1M[
BASE or COlUMBIA
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Delaware Sand
GfOvel Lflfidf
Army Cre
Landfill
Figure 1.4
DELAWARE SAND ft GRAVEL
UPPER POTOMAC CLAY ISOPACH
SCALE IN FEET
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The groundwater within the Columbia is derived from infiltration of rain
water, infiltration from Army Creek, and infiltration from the drainage ditch
east of the Delaware Sand and Gravel Landfill.
As such, water in the Columbia
at the Delaware S~nd and Gravel Landfill moves vertically downward under
unsaturated conditions until it encounters the uppermost Potomac clay.
Water
encountering the Uppermost Potomac clay may build up to a depth of a few feet
creating a saturated thickness in some locations, but within much of the
Delaware Sand and Gravel Landfill, it moves as "sheet flow" on top of the clay
to discharge through the zero area into the UPHZ.
The flow regime in the UPHZ near the Delaware Sand and Gravel Landfill has
changed significantly over time.
The major factors that have affected
groundwater flow and contaminant migration from the Delaware Sand and Gravel
and Army Creek Landfills have been Army Creek, the zero clay area located
between the landfills, and the pumpages from the Llangollen Estates well
field, the Amoco well field, and the Army Creek recovery well field.
In response to water supply and recovery well pumpage, groundwater has moved
within the UPHZ to the southeast, east, south, and southwest at various times
since 1952.
Likewise, after waste emplacement began (1960 for Army Creek
landfill;
1968 for DS&G) contamination from both landfills migrated in those
different directions along with the groundwater.
Since 1982 a westerly flow
pattern has been predominant due to five new recovery-wells installed by New
Castle County.
B.
NATURE OF WASTES
The Delaware Sand and Gravel landfill site was operated from 1968 to 1976.
Wastes were deposited in four distinct areas on the site:
the Drum
Disposal Area, the Ridge Area, the Inert Disposal Area, and the Grantham South
Area (Figure 1.2).
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The Drum DisDosal Area is located just south of the railroad tracks and
occupies 0.42 acres.
The area was originally a pit approximately 150 x 70 x
15 feet.
It is estimated that 7,000 drums in various conditions were disposed
of. in this area of the site.
It has been reported that many of the drums
contents were emptied into the pit prior to crushing and disposing of the
drums.
The drums reportedly contained liquids and sludges from various
industrial processes including perfume, plastics, paint and petroleum r.efining
processes. During the surface removal operation in 1984, the majority of drum
contents were characterized as organic and inorganic solids.
Liquids
characterized included organics and PCB's.
It has been estimated this area
would contain approximately 20,000 yards3 of contaminated material.
The Ridge Area is immediately east of recovery well 13 and covers an area of
0.5 acres.
Surficial wastes, drums, large storage tanks, pallets etc. are
scattered on the slope and top of the ridge.
Subsurface waste disposal has
probably not occurred in this area.
Contaminated surficial soils and surface
wastes in the Ridge Area are estimated at 9722 yards3.
The Inert DisDosa1 Area is approximately 10.7 acres and is topographically the
highest waste disposal area on site.
This area is estimated to contain
approximately 432,000 yards3 of waste material.
Much of the waste is believed
to consist of wire, hose, twine, cork dust, tires, cardboard and styrofoam.
Cars, trucks, trailers, buses, storage tanks, domestic wastes, etc. scatter
the surface of the Inert Disposal Area.
The Grantham South Area is located on the southern side of Grantham Lane.
Disposal of wastes in this area is uncertain, however it is believed inert
waste as well as scattered chemical wastes were deposited in this area.
The
area surface is mostly ash and resinous waste product.
There is little soil
cover.
Based on a topographic map, this area is approximately 35 feet thick
and contains approximately 73,400 yards3 of soil and waste.
NC5003
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C.
EXTENT OF CONTAMINATION
The following is a summary of the extent to which various media (air, surface
soils, formation soils, surface water, stream sediments, and groundwater) are
contaminated at the site.
Surficial Soils
The analytical results for the surficial soils indicate only isolated
"hot spots" with significant concentrations of organics and metals on
both the Ridge and Grantham South areas.
Surficial soils are not a concern at the Drum DisDosal Area because of
the removal action in 1984, which removed surface drums, covered the area
and revegetated. Also the Inert Area is not a concern for surficial soil
contamination.
In the Rid~e Area, sampling detected "hot spots" of metals and organics.
Tables 5.11 and 5.12 in Appendix A summarizes the inorganic and organic
constituents detected in the surface soils of the Ridge Area.
Metals
detected above background included arsenic, antimony, barium, copper and
lead.
The major organic detected was PCB's at concentrations from 97 ppb
to 49,000 ppb.
Contractor personnel noticed several corroded barrels and.
some spilled product in the Ridge Area and sampled some of the spilled
product at sampling location R-14s.
Soil 2 feet. below the spilled
product (sample R-14d) was not contaminated, indicating that the
contamination had not leached vertically 2 feet into the soil profile and
suggesting that migration of the surficial soil contaminants may not be a
large concern.
Grantham South Area sampling revealed two "hot spots" of organics (G-01d
and G-03d).
Tables 5.11 and 5.12 in Appendix A summarize the organic and
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inorganic constituents detected in the suface soils of the Grantham
South Area.
Organics were not of concern in the surficial soils of the
Grantham South Area.
Almost every other sample had increased metals
concentrations (especially copper, lead, nickel, and zinc).
Formation 50ils
The analytical data for the split-spoon samples indicate. that organic and
metal contamination is emanating from the DS&G Drum DisDosal Area and
that some metal contamination is possibly emanating from the Inert
Disposal Area.
Organic compounds were detected in soil boring samples
collected from:
1.
the Drum Disposal Area proper (DGC-6);
2.
the base of the Columbia Formation close to the D~um Disposal Area
(DGC-4);
3.
the uppermost Potomac silty clays beneath and adjacent to the Drum
Disposal Area (DGC-4); and
4.
the top portion of the upper Upper Potomac sands (DGC-4, DGC-7, DGC-
8).
Organic compounds detected in formation soils included, toluene,
methylene chloride, Acetone, 4-Methyl-2 Pentanene, ethylbenzene, 1-2
dichloroethane, xylene, phenol, bis (2-chlor-ethyl) ether, napthalene, 4-
Methylphenol" 2-Methylphenol and 2-Butanone.
Also, Columbia Formation
samples generally have increased metals concentrations (chromium, lead,
and nickel in DGC-4, DGC-6, DGC-8 and DGC-9).
In general, the formation
soil chemistry mimics the groundwater chemistry in extent and nature.
Apparently, contamination is migrating with the groundwater and adsorbing
onto the soils. Organic and Inorganic Analytical Results for soil boring
sampling are presented in Table 5.14, 5.15, and 5.16.
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Surface ~ater and Stream Sediments
~ater and sediments from Army Creek, the Gravel Pit pond, and the
intermittent stream east of DS&G are not significantly degraded due to
the landfills.
Organics were not detectable in either water or
sediments.
In water, the only detectable metals are iron, manganese,
magnesium, and to a lesser extent, b~rium.
For stream sediments,
analytical results for metals are similar to the surficial soil metals
data.
Iron and manganese concentrations are predominant and at the same
order of magnitude as the surficial soils.
Lesser concentrations of
barium, chromium, zinc, lead and copper are also present in the
surficial soils.
Additionally, mercury, arsenic, selenium and beryllium
were detected at very low concentrations.
Thallium, antimony,
cadmium and silver were not detected.
Inorganic Analytical Results for
surface water are summarized in Table 5.17 and 5.18.
In general, Army Creek is the primary concern in terms of surface water
and stream sediments.
However, the impacts of the landfills and the
recovery well discharges on Army Creek do not appear significant and
distinct trends in the surface water quality from upstream to downstream
of the landfills are not apparent.
To further evaluate the environmental
status of Army Creek, a biomonitoring survey of Army Creek was performed
by EPA to evaluate the impacts of the landfills on the biota in the
stream.
The
results indicate there is stress on aquatic life in Army
Creek.
The creek water, in general, has been degraded below normal
surface water.
However, the organisms in the creek are stressed more
upstream of the landfills.
That is, both the benthic survey and the
aquatic chronic toxicity test have shown that the water in the Army Creek
upstream of the landfills is of poorer quality than the downstream
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segment. Sediment toxicity tests have detected chronic toxicity in the
pond stations.
Although the water that is pumped from the recovery wells is degraded
compared to typical well water in the area, and chronic toxicity was
detected in Army Pond Sediments, the benthic data indicated no adverse
effects to Army Creek due to the landfills or the recovery wells.
The
Army Creek environment though is very complicated.
For example, the
Army Creek pond habitat is different from th~ upstream
and downstream
creek segments.
The Army Creek pond is eutropic and the benthic
community there is dominated by pollution tolerant organisms.
The pond tends to act as a treatment system so the quality of the pond
effluent is better than the pond influent.
Regardless, the water quality
of the creek, extending from the upstream to the downstream station, is
all degraded.
Further bioassay studies to continue to monitor the situation will be
completed as a requirement of The National Pollution Discharge Elimination
System permit issued to New Castle County in 1987.
Groundwater
Analytical results from the groundwater sampling indicate the quality of
groundwater in the Upper Potomac Hydrologic Zone in the vicinity of DS&G
has been degraded.
The data indicate that the shallower portion of the
UPHZ, the upper Upper Potomac, is of poorer quality than the deeper,
lower Upper Potomac.
Further, a distinct plume has been identified in
the upper Upper Potomac for organics and metals which emanates from the
DS&G Drum Disposal Area southwestward toward recovery wells RW-13, 31,
RW-12, 29 and 28.
The predominant contaminants identified in this plume
are benzene, toluene, xy1enes, ethyl benzene, bis (2-ch10roethy1) ether,
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MIBK, MEK, iron, and manganese.
Individual plumes for benzene, toluene,
and xylenes in the upper UPHZ are shown in Figures 1.5 through 1.7.
Concentrations of these compounds in groundwater from the lower Upper
Potomac were too low to be contoured.
Organic and metal contamination were detected in a few lower Upper
Potomac wells at very low levels.
The wells that have shown organic
contamination are all located in the immediate vicinity of the Drum
Disposal Area.
Organic and Inorganic analytical results for groundwater sampling are
presented in Table 5.22 and 5.23.
Though not the only source, the DS&G Drum Disposal Area is apparently the
major source of organic groundwater contamination, in the vicinity of
Army Creek.
Inorganic contamination from both DS&G and Army Creek
Landfill is also evident, however, organics predominate DS&G
contamination and inorganics seem to predominate Army Creek Landfill
contamination.
Air
Air monitoring indicates that ambient air quality degradation is not a
concern with respect to volatile organics in the viciriity of DS&G during
non-disruptive on-site activities and that adverse health effects due to
gaseous emissions from the DS&G site are not expected.
Natural
atmospheric dispersion at the site is sufficient to decrease
concentrations of gases emitted from the landfill to below detectable and
harmful limits.
These conclusions are supported historically and by the
results of the Remedial Investigation (Ecology and Environment, Inc.,
1982b; NUS Corporation, 1983b; and Weston, 1986).
-15-
-------
M7>«M1
Dalaworc
Londfni
Figure 1.5
DELAWARE SAND ft GRAVEL
CONCENTRATIONS WITHIN THE
UPPER UPPER POTOMAC FOR 4/M
SCALE IN FTCT
!•. Jt. 31. AW*. AWC7 ft AW003
INr* N* UM« ki
Of
-------
M7IOAJ
SAND"* GRAVEL
-------
Kill III
t^l^MOp ffl"^
-------
Ambient, open-air, total volatile organic concentrations measured during
this investigation at the DS&G Drum Disposal, Inert Disposal, Ridge, and
Grantham South areas were the same as off-site background levels (about 1
. ppm).
Most ambient open-air concentrations measured while drilling were
at background levels; a few readings at DGC-6 were slightly above
background levels.
None were higher than 2ppm.
Higher total volatile organic concentrations were detected during
drilling operations immediately upon opening some of the split spoons
from borings DGC-2 through DGC-9.
These higher concentrations, however,
represent deep soil or groundwater quality, not ambient air quality.
D.
SUMMARY OF SITE RISKS
After evaluating the extent of contamination, the risks were characterized for
each potential or existent exposure pathway.
Since no significant air or
surface water and sediment contamination was detected, it was determined no
risks were posed by these media.
The following three areas were found to
present potential risk to the public health and the environment.
Risk posed by Groundwater Ingestion
Groundwater in the upper Upper Potomac Hydrologic Zone is contaminated by
leachate emanating from the Drum Disposal Area. Groundwater contamination has
migrated away from the Drum Disposal Area; however, the current recovery well
pumping scenerio prevents DS & G contaminants from migrating to any known
water supply sources.
Consequently groundwater ingestion risks were calculated on the potential
exposure though development of domestic wells installed within or on the site
boundary.
-19-
-------
Groundwater from DS&G monitoring wells (DGC-02d, DGC-02s, DGC-04, DGC-05 and
DGC-06) is unsafe for human consumption due to carcinogenic and non-
carcinogenic risks while groundwater from Army Creek recovery wells (RW-13,
31, RW-12, and 29) is unsafe for human consumption due only to carcinogenic
risks. (See table 1 thru table 4).
Risk posed by soil ingestion. inhalation and dermal contact
Organic and Inorganic surficial soil contamination was detected in the
Ridge and Grantham South areas. Only PCB's and arsenic were found to
constitute a carcinogenic risk in surficial soils while lead, antimony,
copper, and barium constitute non-carcinogenic risk. Based on available
data, all risk posed by soil ingestion/inhalation appears limited to the
Ridge Area. Associated Risks are summarized in Table 14.
Surficial soils contamination in the Drum Disposal Area is nonexistent
due to the removal, regrading and soil cap completed in 1984 at this
disposal area.
Risks posed bv site access
4
- Physical injury resulting from uneven terrain, industrial scrap,
protruding waste, etc. remains a concern at the site. The site is
accessable from the east, and south. Also, while public water supply
wells have not been compromised due to groundwater contamination, the
recovery well discharge does present a direct contact risk.
-20-
-------
TABLE 1
Total Carcinogenic Risks (Oral and Inhalation)
From Contamination Found at the Recovery Wells
(Based on April 1986 Sampling)
Recovery Well
NUllber
* Risk
Factor
Primary Constitutent(s)
of Risk Factor
Additional Cancer
Case Ratio
RW-13
1.2 x 10.4
bis(2 chloroethyl) ether
1 in 10,000
RW-3l 4.4 x 10-4 benzene 1 in 2,300
bis(2 chloroethyl) ether
RW-12 1.1 x 10-4 benzene 1 in 10,000
bis(2 chloroethyl) ether
RW-29 1.1 x 10.3 bis(2 chloroethyl) ether 1 in 1,000
NC5005
3/88
ciLI
-~-
-------
,.
TABLE 2
Total Carcinogenic Risks (Oral and Inhalation)
From Contamination Found at the MonitoringWells
(Based on April 1986 Sampling)
Monitor Well Risk Primary Constltutent(s) Additional Cancer
Number Factor of Risk Factor Case Ratio
DGC-02d 1.6 x 10-5 benzene 1 in 100.000
DGC-02s 1.1 x 10.2 benzene 1 in 100
b1s(2 chloroethyl) ether
DGC - 04 4.6 x 10-2 bis(2 chloroethyl) ether 1 in 20
1.2-dichloroethane
methylene chloride
DGC-05 . 4.0 x 10-5 benzene 1 in 25,000
DGC-06
2.2 x 10.5
benzene
1 in 500
bis (2 chloroethyl) ether
1,2 - dichloroethane
NC5005
3/88
~
--2.l. .
-------
TABLE 3
Total Non-Carcinogenic Risks (Oral and Inhalation)
From Contamination Found at the Recovery Wells
(Based on April 1986 Sampling)
Note:
Values greater than 1 indicate risk
Recovery Well
Number
Risk
Factor
Primary Constitutent(s)
of Risk Factor
Risk
Posed
RW -13
0.077
xy1enes
No
RW-3l 0.143 benzene No
xy1enes
RW-12 0.044 ch1orobenzene No
RW-29
0.195
benzene
ch1orobenzene
No
NCS005
3/88
~~
-~-
-------
TABLE 4
Total Non-Carcinogenic Risks (Oral and Inhalation)
From Contamination Found at the Monitoring Wells
(Based on April 1986 Sampling)
Note:
Values greater than 1 indicate risk
Monitor Well Risk
Number Factor
DGC-02d 0.029
DGC-02d 13.082
Primary Constitutent(s)
of Risk Factor
Risk
Posed
toluene
xylenes
toluene
xylenes
MEK
MIBK
DGC - 04
15.544
toluene
xylenes
styrene
MIBK
phenol
DGC-05
0.084
toluene
xylenes
DGC - 06
7.099
ethyl benzene
toluene
xylenes
MEK
NC5005
3/88
~t/-
~-
No
Yes
Yes
No
Yes
-------
TABLE 5
Inorganic8 Detected in Selected Surficial SoU SaJlPles
and Their Associated Risks
Ingestion/Inhalation
&.:.Q1. R-14s P&I R-09d ~
Antimony (Sb) 2.1 8.97 1
Barium (Ba) 1. 83 1 1
Copper (Cu) 1 6.93 1
Lead (Pb) 54.4 1.85 4.5
Arsenic (As)* 1.23E-02 5.43E-02 6.14E-03
PCB* 1.49E-04 4.85E-03 1. 88E-05 9.61E-06
*considered as a carcinogen with appropriate risk level
+100\ absorption is assumed
NC5005
3/88
d,S
-~-
-------
v.
COMMUNITY RELATIONS HISTORY
The DS&G Landfill is located in a sparsely populated and lightly industria1-
ized area south of the city of New Castle.
Along Grantham Lane there are
about ten domestic residences, a private health club, some small commercial
businesses, the State of Delaware Division of Air and Waste Management office
and a small tavern.
There are other residences and small businesses south.of
Grantham Lane along Route 9 and the Llangollen Estates housing development is
about a mile southwest of DS&G.
Residents were invited to 3 public meetings involving the Delaware Sand and
Gravel site.
One prior to the Emergency Removal in the spring of 1984, one
prior to the initiation of The Remedial Investigation/Feasibility Study in
the fall of 1984 and one on March 16, 1988 to solicit comments on the Proposed
Plan.
Attendance at these meetings has been less than 25 people and no
outstanding resistance to activities at the site has been brought to DNREC or
EPA's attention.
A public comment period starting February 26, 1988 and
continuing to April 18, 1988 was utilized to solicit comments from the public
regarding the proposed plan.
The DNREC has attempted to respond to all the comments, in the Responsiveness
Summary which is attached.
-26-
-------
VI.
REMEDIAL ALTERNATIVE OBJECTIVES
Objectives identified for this study included the following:
1)
2)
Select a remedy that is protective of human health and environment
Select a cost effective remedy.
3)
Select a remedy that will attain State and Federal Applicable, Relevant
and Appropriate Requirements upon completion.
4)
Select a remedy that uses permanent solutions and alternative
technologies to the maximum extent practicable.
5)
Select a remedial alternative which prefers treat~ent of the
principal threat to reduce mobility, toxicity and volume of the
hazardous waste.
6)
Select a remedy that provides best results across all evaluation
criteria.
7)
Ensure the chosen groundwater remedial alternative is compatible
with the selected Army Creek Landfill groundwatr alternative.
In approaching these goals, the NCP, 40 CFR 300.68 (F), requires that at least
one alternative from each of the following categories be evaluated within the
requirements of the feasibility study guidance (EPA, 1985).
5)
NC:cjw
NC5004
1)
2)
Alternative for treatment or disposal at an off-site facility;
Alternative which attains applicable or relevant and appropriate
Federal public health or environmental standards;
3)
Alternative which exceeds applicable or relevant and appropriate
public health or environmental standards;
4)
Alternative which does not attain applicable or relevant and
appropriate public health or environmental standards but will
reduce the likelihood of present or future threat from the
hazardous substances;
No action alternative.
-27-
-------
Alternatives were assessed on how adequately they met the above referenced-
goals and objectives.
The alternatives were assessed using the following
eight criteria.
These criteria were developed based upon the requireme~ts of
Section 121 of CERCLA, amended by SARA.
1)
Overall Protection of Human Health and the Environment - All
alternatives were assessed from a standpoint of whether they provided
adequate protection of human health and the environment.
2) Compliance with Applicable, or Relevant, and Appropriate Requirements
(ARAR's) - Alternatives were assessed as to whether they attained legally
applicable or relevant and appropriate requirements of other Federal and
State environmental and public health laws.
3)
Long-term Effectiveness and Permanence - Alternatives were assessed
for the long-term effectiveness and permanence they afford along with the
degree of certainty that the remedy will prove successful.
4)
Reduction of Toxicity, Mobility or Volume - Alternatives which employ
treatment were evaluated for their reduction of toxicity, mobility or
volume.
5)
Short term Effectiveness - Alternatives were assessed on how
effective they were on a short term basis.
6)
Implementability - Alternatives were assessed on the technical and
administrative considerations of actually implementing the
alternative.
7)
Community Acceptance - Alternatives were assessed on predicted
community attitudes and actual responses toward the alternatives.
8)
Cost - Alternatives were also assessed on various types of costs to
be incurred with each alternative.
-28-
-------
Alternatives reaching the detailed evaluation are listed in Table 6 below. per
Disposal Area and Groundwater Plume Management.
,
osw; RHedi.l ktian AltEfn.U" PiChgK for Dttuhd Asllllllllt
3121/88
._----_._----~- I
--------
I Drill Di !tIowl Iru I 1
: iIId Ridge ~H : Intrt Dispowl IrH : linnthM South kH
:--------- .._----: ------------1--
I I I
I I I
: . '10 Action : . tiI Actjpl : . No AcUIII
I I I
I I t
: ': I
: . F.HO¥.l .~ : . SurhClDlDris I . ~i",
: Off ," te CISjloul : RHoviJ II1CI ~i", I
I I I
I I I
I I I
I I I
: . RNOv.l IIId ()!~it, : :
: Incloer.tl ~'f': :
I I I
I I I
I I I
I I I
: - RMOv.I, ~'"Si te : :
: Inciner.tion, iftd : :
: 8iurttlilat.1on of : :
: Soils: :
I I I
I I I
I I
: SrDllldNltlr :
1-"-"-----:
I I
I I
I . St.tus b . :
: No Further Action :
I I
I . I
: . StAtus ~o - :
: Plus TrHtltnt :
I ,
I I
I I
I I
: - CaUl Present ~
: bcoVIrY "'11 J
: 51stll
I
I
I
I
.
I
I
.
I
I
.
I
.--------- -
------------------------------------
-29-
-------
VII. ALTERNATIVE EVALUATION
A.
SOURCE CONTROL
Drum Disposal Area and Ridge Area
Alternative 1. - No Action - The reason for evaluating a No Action
Alternative is to provide a basis for comparison of existing conditions
.'
with other proposed remedial alternatives.
The No Action alternative for
the Drum Disposal Area and Ridge Area would result in no additional
remediation in these areas.
The Drum Disposal Area is the primary source of groundwater contamination
and the Ridge Area is the primary source of soil contamination on the
site.
Groundwater contamination emanating from the Drum Disposal Area
has not had a direct impact on the production wells in Artesian Water
Company we1lfie1d (present receptors); however, contaminants in the
upper upper potomac groundwater aquifer have been detected above
acceptable levels (MCL's or 10-6 risk levels at the site boundary.)
Surficial soil contamination in the Ridge Area has also been determined
to present a direct contact risk.
By leaving the wastes in place, compliance with MCL's at the site
boundary (assuming groundwater contaminant recovery system continues.)
is estimated to be over 30 years.
Also if wastes are not removed or
treated contaminated surficial soils would continue to present a direct
contact risk.
The no action alternative would not reduce volume, toxicity or mobility
of the wastes located in the Drum Disposal and Ridge Area.
-30-
-------
Over the short-term the effectiveness of the no action a1ternative-ii
obviously poor.
No reduction of the potential groundwater ingestion risk
or the surficial soil direct contact Lisk would occur.
Over the 10ng-
term the potential groundwater ingestion risk may be reduced after an add-
itiona1 30 years of operating the groundwater contaminant recovery system.
No cost would be incurred with this source control remedy.
Community
acceptance of the alternative would more than likely be negative since
the alternative presents no improvement over present site conditions.
Alternative 2. - Removal and off-site disposal - This alternative
involves waste characterization in both areas and excavation of the waste
and contaminated soils in the drum disposal area and contaminated
surficial soils from the ridge area.
No treatment of wastes and soils
would occur with this alternative.
Wastes and contaminated soils would
be transported to an off-site land disposal facility.
This alternative would be required to meet Resource Conservation and
Recovery Act transportation and disposal requirements.
Land disposal
restrictions under subtitle C of RCRA are expected to negatively affect
this alternative.
After November of 1988, it will be difficult to comply
with land disposal restrictions of the wastes and contaminated s011s
unless treatment is utilized prior to disposal.
This alternative involves handling approximately 36,000 tons of wastes
and contaminated soils that have been on-site and compacting for several
years.
Disturbing these materials will likely cause bulking, an
increase in volume.
Removal and disposal without treatment do nothing to
-31-
-------
reduce the waste's toxicity.
Likewise, nothing would be done to decrease
the waste's mobility while on-site; instead, the waste would be removed
from the site altogether.
The short-term effectiveness 1s only fair.
While the remedy works to
reduce the risks, the community and, especially, the workers face
increased exposure risks) during waste removal, characterization,
transportation, and redisposal.
This increased exposure period, however,
is short-lived.
Once the waste has been removed and redisposed off-site,
there is minimal potential of future releases.
The long-term
effectiveness, thus, would be good, and since the wastes are actually
removed from the site, the solution offers a high degree of permanance
relative to on-site conditions.
Implementation of this alternative would be technologically and
operationally straightforward.
Transportation permits and off-site
disposal arrangements would be necessary.
Excavation equipment and
operators could be arranged for by the time off-site action permitting
would be complete.
No major construction would be necessary to implement
this alternative.
Overall, its implementability is good.
Proposing a removal and off-site disposal action for the Drum Disposal
Area and the Ridge Area would result in mixed community reaction.
Though
residents would react adversely to the transportation of haz~rdous wastes
through their communities, they would support the total removal of the
wastes from their area.
Overall community acceptance, then, should be
good.
Costs for this alternative for the Drum Disposal Area and for the Ridge
-32-
-------
Area total approximately $20,250,000.
Waste Characterization and
Excavation for the Drum Disposal Area and the Ridge Area is estimated at
$3,250,000.
Off-site disposal of the excavated waste is estimated at
approximately $17,000,000.
No operation and maintenance costs would be
involved with this source control alternative.
This alternative is most
expensive of the four source control alternatives evaluated for the Drum
Disposal and Ridge Area.
Alternative 3 - Removal, On-Site Incineration - Under this alternative
wastes would be removed from the ridge and drum disposal area as in
Alternative 2.
Treatment of wastes and contaminated soils would occur
via on-site incineration.
Soils and waste in the Drum Disposal Area
would be excavated to a level where the leachate emanating from them to
the groundwater no longer poses an unacceptable long term carcinogenic
risk.
These levels have been calculated and are presented in Table 7,
Column IV.
Surficial Soils and waste in the ridge area would be excavated to
approximately 5 feet in depth to ensure no residual contamination.
Incineration of the material, approximately 36,000 tons, would be
conducted with a mobile incinerator.
The most appropriate type of
incinerator would be determined during the remedial design.
The
estimated time frame for incineration is 3 to 5 years.
All emissions
from the incineration operation would meet Air Pollution Control
Regulations as well as RCRA Regulations.
Residual ash, would be sampled
to determine remaining constituents followed by appropriate disposal of
ash.
-33-
-------
.
While permits are not required for on-site remedial actions at Superfund
Sites, any action must meet the substantive technical requirements of the
permit process.
The incineration unit would comply with all the
applicable requirements of 40 CFR Part 264 Subpart 0 of RCRA, and also Air
Quality Control regulations.
This alternative in conjunction with continued operation of the
groundwater contaminant recovery system would assist in meeting MCL's at
the site boundary.
The estimated time frame for reaching acceptable
levels of contaminants in groundwater is less than ten years after removal
While this remedy eventually reduces the risks to the public, the short-
term effectiveness is only fair.
The community and the workers face
increased exposure risks, while on-site; however, these risks would be mitigated
through proper health and safety programs and site access restrictions.
Once the wastes have been incinerated, the residual risk and the
potential of future releases include only those related to the ash from
the incineration process.
Operation and maintenance of the incinerator
would continue as long as it is in use, but with proper training and
health and safety programs, associated risk would be minimized.
Overall,
the long-term effectiveness of this package would be good.
The permanence of this remedy would be good to excellent.
All the wastes
from the Ridge Area and the Drum Disposal Area would be fed to the
incinerator and most would be destroyed.
Only residual ash would need to
be disposed of on. or off-site, and since contaminant content would be
low, post-disposal management would be minimal.
-34-
-------
Compound
• >
Toluene (9)
Methylene Chloride
Acetone (9)
4-Methyl-2Pentanone (9)
•t i
Ethylbenzene (9)
1,2-Dichloroethane
Xylene (9)
Phenol (9)
Bis(2-Chloroethyl)Ether
Naphthalene (8)
4-Methylphenol (9)
2-Methylphenol (9)
2-Butanone
Acceptable Water
Exposure (ug/1)
2000
0.7
9500
£750
£80
5
2
3500
0.03
400
1750
1750
1750
Table 7
Source
MCLG
CAGUCR
SPHEM
IRIS (AIC)
MCLG
MCL
MCL
IRIS (oral)
(RfD)
10~6 RISK
ENVIRON RfD
SPHEM
SPHEM
IRIS
Koc
Acceptable Soil 1
Concentration (ug/kg)
Hi^^st Soil
Cone. Observe
At DS+G (ug/k
300
8.8
2.2
4.5**
1100
14
240
14.2
13.9
1072A
264A
*A
35
• 6.0X106
61.6
7.7xl04
7.88xl04
7.48xl06
700
4800
4.97X105
4.17
4.3X106
4.6xl06
4.6xl06
6.1xl05
1900
725
4400
3100
200
1200
1100
2100
180
4200
240
1400
7600
*
**
Acceptable soil concentrations calculated from product of acceptable water exposure
and koc value, followed by ten-fold allowance for dilution, i.e. (Acceptable
water Exposure)x(Koc)x(10)
I = Koc calculated from koc/kow relationships reported in Lyman etal.(1982)
equation for napthalene: Log Koc = 1.00 Log Kow - 0.21
equation for 4-methylphenol: Log Koc = 0.544 Log Kow + 1.377
No Kow data available for 2-methylphenol; assume value similar to 4-methylphenol
No Kow data available - assume value similar to MIBK Peroxide
-35-
-------
Incineration is technologically developed and reliable.
Incinerators: and
storage buildings are availabl~ from several manufacturers, and both
could be constructed within 6 months.
Excavation equipment and operators
would also be readily available.
Necessary storage and disposal
facilities would be on-site, so there would be no availability problems
and no permit applications.
All these factors affect the implement-
ability of this remedy.
In general, the implementability of this
remedial package would be good.
The neighboring communities would probably view the extensive management
of hazardous wastes as a hazard.
The construction and operation of an
incinerator close to their homes would also likely generate an adverse
reaction.
Therefore, community acceptance of this plan is considered
marginal.
Cost estimates for this alternative for the Ridge Area total $18,250,000.
Waste Characterization and Removal for the Drum Disposal Area and for the
Ridge Area is estimated at $3,250,000.
On-site incineration of 36,000
tons of waste and contaminated soil with a mobile incinerator and
disposal of residual ash is estimated at $15,000,000.
No operation and
maintenance costs would occur with this source control alternative.
This
alternative is the least expensive of the four source control alterna-
tives evaluated for the Drum Disposal and Ridge Area.
Alternative 4 - Remova1-0n-Site Incineration and Biorec1amation of soils
- This alternative is similar to Alternative 3, however, additional
treatment in the drum disposal area would occur to ensure no remaining
. soil contamination would contribute to groundwater contamination.
-36-
-------
Treatment of soil would be through bioreclamation of soils using
.
microorganisms to biodegrade organic contaminants.
This alternative is the same as the previous package with the addition of
bioreclamation of soils.
All of the criteria that were met by
alternative 3 are met or exceeded by this alternative.
Specifically,
soils would be treated beyond the acceptable levels listed in Table 15.
With the addition of bioreclamation, the long-term effectiveness ranks
good.
Bioreclamation treats any contaminated material missed in removal
operations, therefore assisting the groundwater contaminant recovery
system in meeting MCL's at the site boundary. The insurance provided by
the bioreclamation also upgrades the probable compliance with ARAR's to
excellent.
The imp1ementabi1ity of this alternative is be1eived to be
good.
Prior to implementation of bioreclamation of DS & G, lab studies
are necessary to determine optimal conditions needed.
Also site specific
studies would be necessary to accurately predict the treatability of
specific contaminants, substrate removal rates, adn overall effectiveness
and performance.
It is estimated that the process would be effective in
reducing residual contaminants in the soil after removal has occurred.
Like the package without biorec1amation, it is be1eived this package
would reduce the volume, toxicity and mobility of the contaminated soils
in the Drum Disposal Area.
The cost estimate for this remedy is higher
than that of the previous alternative to reflect biorec1amation costs.
The estimate is $19,985,400.
Waste Characterization and Removal for the
Drum Disposal Area and for the Ridge Area is estimated at 3,250,000.
Incineration and disposal of residual ash is estimated at $15,000,000.
-37-
-------
-
Additional bioreclamation of contaminated soil, remaining after removal,
is estimated at $1,735,400.
This alternative is more expensive than
alternative 3 Removal and On-Site Incineration; however it is less
expensive than Alternative 2 Removal and Off-Site Disposal.
Inert Disposal Area
Alternative 1. - No Action - The reason for presenting a No Action
Alternative is to provide a basis for comparison of existing conditions
with other proposed remedial alternatives.
The no-action alternatives
for the Inert Disposal area would result in no remedial action in this
disposal area.
This alternative would not meet the ARAR's for this area covered under
40 CFR 264 RCRA Subtitle D and Delaware Solid Waste regulations 7
Delaware Code, Chapter 60, for proper closure of a solid waste landfill.
Since this area contributes little to no contamination problem at the
site, the cnly short-term and long-term risk is the existing risk of
physical injury from surface debris and inert wastes.
Also over the
long-term, the existing inert waste piles will continue to attract
illegal dumping at the site.
No costs would be incurred with the no action alternati~e.
The no action alternative at the Inert Area would not change-the
appearance of the site and therefore would not be favored by the public.
Alternative 2. - Surface Debris Removal and Capping - This
alternative
involves removing surface debris (i.e., trucks, wood debris, trash) from
-38-
-------
the surface, regrade and apply a surface cap as per DNREC Solid Wast;
R~gu1ations.
This alternative would meet the ARAR's (RCRA Subtitle D
and DNREC Solid Waste Regulations) for this area.
Reduction of toxicity andmobi11ty of the waste is not a major concern at
this area on site since there is not any apparent contribution to site
contamination from this area.
Reduction of volume of solid waste would
not occur with this alternative.
The short term effectiveness of this alternative would be elimination of
the physical injury risk this area poses.
Over the long-term this
. alternative would reduce the continued illegal dumping at the site.
Surface cleanup procedures and capping are well developed, reliable, and
available technologies.
Because wastes to be disposed off site are not
hazardous, there would be no problem arranging for a disposal facility to
accept the wastes.
\
beneficial results would be immediate.
Cleanup and capping would be completed in a year, and
Community acceptance of this
alternative is highly favorable.
The community would favor an
improvement in the appearance of the landfill and also a reduction of
illegal dumping in the area.
The cost of this alternative is estimated at $1,161,000 for capping the
Inert Area.
Grantha1D South
Alternative 1. - No Action - The reason for presenting a No Action
Alternative is to provide a basis for comparison of existing conditions
with other proposed remedial alternatives.
The No Action Alternative in
-39-
-------
the Grantham South Area would result in no remedial action in this'
disposal area.
The no action alternative does not meet closure
requirements under Federal and State RCRA requirements.
Since it is
believed hazardous wastes. may be distributed randomly throughout the
basically inert waste, the closure requirement under hazardous waste
regulations should be met.
No other regulations are applicable, relevant
and/or appropriate for this area.
The no action alternative would not reduce volume, or toxicity. Since the
Grantham South Area is virtually dewatered, the mobility of contaminants
is low and the contribution to groundwater contamination from this area
is beleived to be minimal.
The potential direct contact risk in this area would not be reduced in
the short or long term with this alternative.
No cost would be incurred with this alternative.
Community acceptance
,
of this alternative would not be favorable since wastes would continue to
be exposed and a direct contact risk would still exist.
Alternative 2. - Capping - Under this alternative, the surface would be
regraded and capped.
The cap would comply with Resource Conservation and
Recovery Act closure requirements, 40 CFR 264 RCRA Subtitle C.
C~pping this area would adhere to RCRA closure-requirements.. No other
regulations are applicable, relevant and/or appropriate for this area.
This action would not reduce the volume and toxicity of wastes in this
area;
however the potential mobility of the contaminants would be
. reduced.
-40-
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Capping this area would reduce the direct contact risk associated with
this alternative.
Capping of the area would be completed in four months.
The long-term effectiveness of this remedy would be good.
Potential
leachate generation in this area would be prevented in the long-term.
Since capping is a well developed, reliable and available technology, the
imp1ementabi1ity of this alternative is good.
Since the alternative would alleviate both risks presented in this area,
it is believed the community would accept this alternative.
The cost estimated for capping the Grantham South Area is $830,000.
B.
GROUND~ATER PLUME MANAGEMENT
Groundwater Contamination Plume
Alternative 1. - Status Quo - No further action.
This alternative
involves continuing the groundwater recovery system specifically wells R~
13, ~e11 31, R~12, ~el1 29, and ~ell 28, until acceptable risk levels are
met at mo~itoring wells near the site boundary.
The acceptable risk
levels for designated contaminants detected in monitoring of recovery
wells are listed in table 7 Column I.
Discharge to Army Creek of recovered
contaminated groundwater would continue.
This alternative would continue
to effectively recover contaminated groundwater from the drum disposal
area at Delaware Sand & Gravel.
Federal and State ARAR's for this alternative include Safe Drinking ~ater
Act, SD~A 42 USC 300, (MCL's or 10-6 risk levels for groundwater)
National pollution Discharge Elimination System, ~A 40 CFR 122.
This
. alternative would assist in meeting requirements of SD~A (i.e. t MCL's) at
-41-
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or near the site boundary.
.
It has been determined however that direct
discharge of recovery well ground-water would not meet the NPDES
requirements.
This alternative does effect a change in the the mobility of contaminated
groundwater; however, the volume and toxicity is not reduced.
Over the short-term this alternative does not reduce exposure risk at the
recovery well discharge point or eliminate any potential Army Creek water
quality degradation.
This alternative is implementable.
It was initially implemented in 1974
by New Castle County with alterations for better contaminant recovery in
1979.
Community acceptance is fair since the recovery well system does and
will continue to protect water supply wells from contamination
emanating from DS&G.
The cost of this alternative is estimated at $1,081,000.
Installation of
the 5 recovery well system is estimated at $322,130.
Operation and
Maintenance of the recovery wells for an estimated 10 years is $759,613.
Operation and maintenance includes quarterly sampling of at least 10
monitoring wells.
Alternative 2. - Status Quo - Plus Treatment.
This alternative
includes Alternative 1 and treatment of the recovery well groundwater
before discharge to Army Creek.
. The type of treatment required would be determined by the Army Creek
-42-
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second operable unit Record of Decision and the Regulations on National
Pollution Discharge Eliminations.
This alternative has the same ARAR's as the alternative 1; however, this
alternative would meet all those requirements of SDWA and NPDES.
Reduction of volume, toxicity and mobility of contaminated groundwater
would occur, since treatment of groundwater would be completed under this
alternative.
Reduction of risk at the recovery well discharge point or the potential
risk to Army Creek would be eliminated shortly after implementation of
the alternative.
Over the long-term (less than 10 years after source
removal) this alternative would be successful in restoring the aquifer to
acceptable groundwater ingestion levels and also in restoring Army Creek.
The permanence of the remedy in restoring affected areas is good.
Sludges frore treatment of groundwater would be handled in an appropriate
manner.
Implementability of the recovery well system is technical feasible as
well as construction and maintenance of the treatment facility.
Community acceptance of this alternative would be favorable since it
would reduce any potential for Army Creek degradation and eliminate
direct exposure risks.
The total cost for this alternative is $4.753,000.
Installation of the
recovery well system and treatment plant is estimated at $1.418,948.
Operation and maintenance for an estimated ten years is approximately
$3,334,501.
Operation and maintenance includes quarterly sampling of at
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least 10 monitoring wells.
This alternative is much higher than other
groundwater plume migration management alternatives; however it would
meet all ARAR's and be protective of human health and the environment.
Alternative 3. - Cease Present Recovery Well System. - This alternative
would result in no action for remediating the groundwater contamination
plume.
This alternative is included for comparison with other
alternatives.
This alternative would not meet the relevant and appropriate requirements
of meeting MCL's or 10-6 risk levels at the site boundary.
No reduction of volume, toxicity and mobility of contaminated
groundwater would exist with this alternative.
Over the short-term eliminating the groundwater recovery well system
would still be protective of public health at the present day receptor;
however potential groundwater users on or near the site may not be
protected over the long-term.
Also, model simulations show contaminated
water may reach Army Creek as base flow after the cessation of recovery
wells.
Community acceptance of this alternative would be unfavorable since
the cessation of the recovery well system may not be protective of
public health and the environment.
No major costs would be incurred with
this alternative.
A qualitative evaluation of Remedial Action Alternatives as per criteria
listed in'Alternative Objectives section are presented in Table 8.
NC5~06
-44-
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Table 8
3124/11 triteri. 'ew 5I1.di.. Df ...,
,
,.IDf2
I IrN Df I Wltti.. i..r. I !iIIart - T.. I ~-Terl I I I =Ii.e I t.uit, I 1
I Cane.,. ......1 'K'" I 'aldt" .. Mml, I £fI.di..... I Eff. i WIIIII I hrlllllllCt I ,.,I...t..Uity I iii MIll I kc.,h.lCt I taat 1
1-- 1
I I III~II_. I ID I ID I ,"trid I I I 1 I
1 he IiIfCllll 1 - .., leU.. - St&t." I" dIIIit I. taidt, I ,Id..di.. I I'IIMU.. I KctHi.mt, I lOt wUuIIlt I ID I ID I I
I IrH I I II n.jIll "UIt, I Df ,iu I afrlu I I I I I. I
IIZIIIII I. . 1.1 I I
I .. the I I I I . I 1 I I
.
1 Ai. IrN I - III" ~Id..hatl. l.r. I~ I rilk.., I 110 I tliffladt, I I I I
1 I .. IIIIIIWII I .. ~ I. t.ldt, I illCt l1li I r_cti.. ":'"Jurr4t I il citll'l~ I ,.. I ... I I1O,Z!O,ooo I
1 I - Df'1itt Ii"" I .. dI8it I. ..mi, I _I.. I Df rlu I aff-.It. pit tI I I I I
I I I I r.ow.1 I I I I I I
I I I I I
1 I I
1 1 I I I 1 I I
I I - IIftt. (WKt.hati.. I I I t.IIIII[lII, I I I
I I " ~&I I ¥AI. ,_U.. I riu .., 110 I ''''''111 I I I
I I - TIIpCI'.' Stew.. 1 ,..Ielt, rltlldl. 1 Iler.... r_U. ~...t 1 t,Ht.lllt, I ,.. I ..,i 1111 1I.,Z!O,ooo I
I I Dl1ite Ild_ItI... I Mmt, nMtl. I wi.. of rlu rllpdrlll I It'''l" I I I
. I I 1M Chitt Ii"" I I r.owu I ...... I I I
I I I I I I I I
I I I I I I I I
I I I
I I I I I I I I
I I . illite OI.Kt.II&tI. I I I I I I
I I '" IIIIIIWII I I rlu.., I I I I
I I - '''''.' ...., I 1rII. rlllllrt1. I I.,.. rltlldllll I . I tlUfiRit I I
I I hlte 'ltl_ItI., I ,..Ielt, rltlldl. I wi.. of rl. I ....... I ta "Nt I ,.. ..,1..1 .I..ID.- I
I I.. Dt1Ue II~ I Mmi, ,..1. I ~U I r.rlll I ehlll 18t" I 1
I I . liew.1MatI. Df Sall1 I I I I I I
I I I I I I 1 I
I I 1 I I I I I
I I
I I 1"~I.... I ,.Icll I ,.lcll I r"trld I I I
I ... II""" I . .. ktl.. - ..ta.. I" ~ II taldt, I -... I . .... I KCIII..mi, I lOt WUulll. I . . I
I IrH I I .. dI8it I. "lilt, I Itlll .11t I Itill IIIIt I I I I
I I I
I I I I I 1 I I I
I 1- k'" "II"" I Val. rltlldl. I rl".., I I ,..Iatllt I I I
I I 1M OIl11t. 11..1 II ~ I. t..ldt, I I.,.. I rlllldi. I 1""'1... I ...- I ... ptI '1.1'1.000 I
I I - c."i.. I P8tI1~e ..mty I wi.. I If rI. I ,.rlll I ttdlDllIIY I I
I 1 I rlllidi. I r.owil I I I I I
I I I ,. I I I I I I
. lirllllldllat. aitewt.. Mr &11 iii"" ... II 11tarJIIF1btl1IItIIr U. IF"""" .. Df aKn.
-45-
-------
Table 8
3/24/11 Crit.il '11' Sliidie. 01 ....,
,. 2 01 2
1 kHoI I 1III6d1. t. 111.1 I 1IIIt-,.. I ~,.. I I I =".. I r.1_1t, I I
1 C..I ..... "'" IT.ldt,. 1M Mill ,I £1f.U.... I £ff.l- I Pw.... I 1..1....nU, I III MIll I Ia..t.. I flit I
1 -I
1 I 1 .. c-.. I. -. I . . 1 ,"trld 1 I 1 I 1
01 "...1iIub 1 -II ktl. -"ltlte.. I" C'-It t. tIIldt, I ,..dl. ,IMU. I 1COIIi'lIIt, 1 lilt ...U~I. I . I . I I
1 kH 1 III G8j11. _UIt, I If ,I. If ,I. 1 1 1 1 I I
1 I 1
1 1 1 It 0.,. II -. 1 ,I. -, 1 ,..1.1, 1 I 1 1 I
1 1 - tlfflll 1 It ~ II tIIldt, 1 llIUHII ,IMU. I i..,..l- 1 ".... I '" 1 fil, I 8110.000 1
1 1 1 ,....11 _illt, 1 ..I", 01 ,I. I '.,.. 1 tldllal.., 1 1 1 1
I 1 1 ,IMU. 1 '8IV11 1 1 1 1 I I
I
1- 1
1 1 III~II_. I . . I ...lItail 1 .I...Iull, 1 1 1 I
1 GrCUl6ild. 1 - lID Idl. - Stat." I It "-it II t.ldt, 1 ,..U. ,.U. 1 ,.oww, -II 1 ~a:rtt I . 1 fal, 1 11.111.000 1
1 1 1 .. ~ tl _mt, I 01 ,I. II ,iI. I .pt. 1 I 1 1 1
I I I
I 1 1 1 I I 1 I 1 1 I
I 1 - StltlS .. 1 II cUItI II WIll. 1 ,..dl. 1 ,..ldl. 1 _llIbill 1 "... 1 1 1 1
1 1 - o...Itt T,... 1 '.Ielt, ,... I If 1 If 1 ,...., _II 1 ~IIY 1 '" I ... I 84,153,000 I
1 1 - IbIltll'ill 1 It "-It II _lilt, 1 rl. 1 ,1. I .,.t. I I 1 I I
1 I I I I I I I I I I
1 1 I
1 I I I I I 1 I I I I
1 1 - r.slll 1ItMr, IIU 1 ~... -. 1 .I,.t ,.t.t 1 .1,1d ccat.t 1 "UII' I 1 1 I .t.... cOlts I
1 I ~ I ,16d1. I ,I. I ,I. I ItrHl 1 lilt ...U~I. I . I . 1 1
1 1 - IbII tarlll III w.11 t.ldt, I iller"" 1 iltr... I I I I I I
1 I I It D8iI i. _Ult, I I I I 1 I I I
-46-
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VIII.DOCUMENTATION OF SIGNIFICANT CHANGES
No significant changes to the preferred alternative presented in the
proposed plan have occurred.
IX. SELECTED REMEDIAL ALTERNATIVE
According to 40 CFR Section 300.68(i) of the NCP, the appropriate extent
of remedy shall be determined by the lead agency's selection of a cost-
effective remedial alternative that e~fectively mitigates and minimizes
threats to and provides adequate protection of human health and the
environment.
In addition, CERCLA requires selection of a remedy which
provides protection to human health and the environment, which is cost-
effective and utilizes permanent solutions and alternative treatment
technologies or resource recovery options, to the maximum extent
practicable and attains federal and state ARAR's to the greatest extent
practicable.
In addition, treatment of the principal threat at the site
to reduce the mobility, toxicity and volume of the hazardous substance is
preferred.
The remedy selected for each disposal area and for
groundwater plume management resulted in the Selected Remedial
Alternative "Package" discussed below.
A.
DESCRIPTION OF SELECTED REMEDIAL ALTERNATIVE PACKAGE AND PERFORMANCE GOALS
Drum Disposal and Ridge Area
Alternative 3. - Removal and On-Site
Incineration - Waste characterization in both areas will occur to
distinctly define areas before removal.
Complete removal of contaminated
wastes and soils will occur in both areas.
In the Ridge Area removal
will occur to approximately a 5 foot depth across the entire area.
In
. the drum disposal area removal of soils will occur until the accept-
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able soil concentrations listed in Table 7 are met.
Upon completion.
of complete removal, the areas will be properly graded and revegetated.
Wastes and contaminated soils will then be treated on-site by
incineration.
The most appropriate type of incinerator to be used on-
site will be determined via engineering evaluation and treatability
studies during the remedial design.
Residual ash, scrubber water etc.
from the incineration operation will be analyzed and disposed of in
accordance with all State and Federal Resource Conservation Recovery Act
Subtitle C or D requirements.
The incinerator will operate as per A~r Pollution Control Regulations, 40
CFR 60 CAA, as well as Resource Conservation and Recovery Act Part 264
Subpart 0 Regulations.
It is estimated this portion of the remedial
action package will take 3 to 5 years.
Inert Area
Alternative 2. - Removal of Surface Debris and Capping.
Before
attempting to cap this area removal of all surface debris (i.e., trucks,
buses, cars, etc.) must occur.
The surface debris will be removed from
the site in order to prevent physical injury and disturbance of any
remedial action and operation and maintenance.
Capping of this area will
occur as per the Delaware Solid Waste Regulations (7 Delaware Code
Chapter 60).
The capping operation is estimated to be completed in one
year.
Grantham South Area
Alternative 2. - Capping - Capping of this area will comply with the RCRA
requirements (40 CFR 264 RCRA Subtitle C) for permeability.
An
appropriate type of cap will be chosen in the remedial design
-48-
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phase.
The capping operation is estimated to be completed in
four to six months.
Groundwater Plume
Alternative 2." - Groundwater Pumping and Treatment of Discharge -
Recovery of contaminated groundwater will occur with the 5 recovery well
system - RW-13, Well 31, RW-12, Well 29, Well-29 - currently recovering
DS&G contamination.
Pumping will continue with quarterly inspections and
maintenance of the recovery well system.
Wells will be inspected and
maintained to insure their continual functioning.
Monitoring of at least
10 monitoring and/or recovery wells in the area of Delaware Sand and
Gravel will be required quarterly in order to evaluate the continued
effectiveness of the remedial action.
Cessation of the recovery well system will occur sometime after source
removal has occurred and the groundwater at the site boundary has
consistently met the acceptable water exposure levels indicated in Table
7. Presently 10 years of recovery well operation is estimated.
Recovered contaminated groundwater will be treated as per the National
Pollution Discharge Elimination System regulations before being
discharged into Army Creek.
Queration and Maintenance of the Selected Remedial Alternative
Drum Disposal and Ridge Area - Maintenance of land surface in response to
subsidence and/or erosion will be required.
Inert Area and Grantham South Area - Maintenance of both caps will be
, required to ensure they are functioning properly.
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Groundwater/Surface Water - Sediments
Upon cessation of the groundwater recovery and treatment system
(cessation of discharge to Army Creek) the pond and creek water levels
and vegetation will be evaluated for 2 years.
If a drastic reduction of
water flow occurs and Phragmites becomes the dominant species, it is
recommended the area be seeded with indigenous species.
Also required
will be 2 sediment sampling events in Army Creek: one after 5 years of
initiation of remedial action and one a year after pumping and treatment
has ceased.
The sediment sampling will include sediment chemistry and
sediment bioassays. .
B.
STATUTORY DETERMINATIONS
Drum DisDosal and Rid~e Area - The selected alternative, Removal and
Incineration for the Drum Disposal Area, was determined to be protective
of human health and the environment, to have manageable short-term risks,
to be cost effective, to attain all ARAR's and reduce the toxicity,
mobility or volume of wastes.
Alternative 1 for the Drum Disposal and Ridge Areas - No Action - was
determined to leave potential groundwater ingestion risk for a minimum of
30 years and also do nothing to reduce the direct contact risk to surface
soils in the Ridge Area.
Alternative 2 Removal and off-site disposal was
found to reduce on-site risks; however, this alternative had the
potential to produce long-term risks at an off-site facility.
Alternative 4 Removal - On-Site Incineration and Bioreclamation of soils
was determined to be over protective of human health and the environment.
. Consequently, Alternative 3 was determined to be the best alternative for
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adequately protecting human health and the environment in the Drum
Disposal and Ridge Areas of the site.
Each alternative evaluated for the Drum Disposal and Ridge Areas
presented some degree of short-term risks.
Removal and incineration pose
short-term risks associated with removal, and incineration.
These could
be properly mitigated through proper health and safety programs and site
access restriction.
Also the long-term effectiveness (reduction of
risk) of the selected alternative for the Drum Didsposa1 and Ridge Area
for out weigh the manageable short-term risks.
The selected remedy affords overall effectiveness proportional to its
costs.
Of the four alternatives presented for the Drum Disposal and
Ridge Area the one chosen is estimated to cost $18,250,000.
This cost is
less than the other 3 alternatives, and it provides the best overall
effectiveness of the four alternatives.
The selected alternative for the Drum Disposal and Ridge Area is
consistent with all applicable or relevant and appropriate State and Federal
requirements listed below.
1.
National Primary Drinking Water Standards pursuant to SDWA, 42 USC
3~0, and/or appropriate risk levels for potential exposure to
contaminated groundwater.
2:
Federal and State Pollution Discharge Elimination Standards pursuant
to CWA, 40 CFR 122, for treatment and discharge of recovered
groundwater.
3.
Federal and State RCRA regulations pursuant to 40 CFR 264 RCRA
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Subtitle C for closure of a hazardous waste landfill with waste ih
place.
4.
State Solid Waste Regulations pursuant to 7 Delaware Code, Chapter
60, for closure of a Solid Waste landfill with waste in place.
5.
Federal and State Ambient Air Quality Standards pursuant to 40 CFR 60
CAA for control of emissions during the operation of an on-site
incinerator.
6.
Federal and State RCRA regulations pursuant to Part 264 Subpart 0 of
RCRA for design and operation requirements of hazardous waste
incinerator.
7.
Federal and State Coastal Zone Management requirements pursuant to
Delaware Code Chapter 70 for operation of an incinerator within a
coastal zone area.
8.
Delaware River Basin Commission and State of Delaware Water Supply
requirements for continued operation of the recovery well system.
Alternative 1 No Action attained none of the ARAR's, Alternative 2
attained some, but compliance with RCRA land disposal requirements would
cause p~oblems when implementing this alternative.
Alternative 3
attained all ARAR's to a degree over and above those required for
protection of human health and the environment.
The selected alternative for the Drum Disposal and Ridge Area also
satisfies the statutory preference for remedies employing treatment that
permanently and significantly reduces the toxicity, mobility or volume of
hazardous substances.
Incineration of wastes and soils from the Drum
Disposal and Ridge Areas well permanently reduce the volume, toxicity and
-52-
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mobility of waste and contaminated soil and also indirectly reduces the
leaching of contaminants into the groundwater.
Alternatives 1 and 2 did not reduce to any degree the toxicity, mobility
or volume of hazardous waste.
Alternative 3 further reduced the
toxicity, mobility and volume of wastes in soils, however this was
determined to be over protective and not cost-effective.
Inert Area - The selected alternative for the Inert Area was determined
to be protective of human health and the environment, to eleiminate long-
term risks, to be cost effective, and to atttain all ARAR's.
In the Inert Area Alternative 2 Surface Debris Removal and Capping
elimates the physical contact risk associated with this area and
therefore was determined to be protective of human health and the
environment.
Alternative 1 - No Action did not eliminate the present
risk and therefore could not be considered protective.
Alternative 2 for the Inert Area in the short-term presents no risk and
it also eliminated the physical injury risk as well as the continued
potential for illegal dumping.
Alternative 1 No Action eliminated no
risks.
Alternative 2 for the Inert Area also is consistent with the applicable
RCRA subtitle D or Delaware Solid Waste Regulations.
Alternative 1
does not attain the above mentioned ARAR.
For the Inert Area the capping alternative was determined to be the best
alternative when overall effectiveness and cost was considered.
The
-53-
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~
capping option was more expensive than the no action; however capping was
less expensive than removal of wastes and off-site disposal.
- Grantham South. The selected alternative, Capping for the Grantham
South Area; was determined to be protective of human health and the
environment to mitigate short and long-term risks, to be cost effective,
to attain all ARAR's and reduce the mobility of hazardous wastes.
In the Grantham South Area Alternative 2 Capping was determined to
eliminate any direct contact risk and also reduce potential migration
of hazardous constituents into the groundwater.
Alternative one did not
reduce any risks and therefore was not protective of human health and the
environment.
In this area the capping alternative was determined to be the best
alternative when overall effectiveness and cost was considered.
The
capping option was more expensive than the no action; however capping
was less expensive than removal of wastes and disposal or treatment.
In the Grantham South Area Alternative 2 Capping is consistent with the
applicable RCRA Subtitle C closure requirements.
Alternative 1 - No
Action does not attain the above mentioned ARAR.
Groundwater Plume Manaiement . The selected Alternative 2 Pump and treat
for the Groundwater Plume was determined to be-protective of human health
and the environment, to mitigate long-term risks, to be cost-effective,
to attain all ARAR's and reduce the mobility toxicity and volume of
hazardous substances in the groundwater.
-54-
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.
In the Groundwater Plume Management Alternative 2, Pump and Treatment was
determined to reduce the groundwater ingestion risk (in conjunction with
source removal) in less than 10 years; therefore in the long run being
protective of the human health;
Also the alternative treats the
discharge unlike alternative 1 (pumping with no treatment) making the
selected remedy protective of the environment.
Alternative 3 No Action
was not protective of human health and the environment.
No short-term risks to on-site workers was determined for any of the
groundwater plume management alternatives.
The selected groundwater alternative was determined to be the best
alternative when overall effectiveness and cost was considered.
The
Alternative 2 was estimated at $4,753,000, well over the cost of
Alternatives 1 and 3.
However, Alternatives land 3 were determined not
to be protective of human health and the environment.
Alternative 2 for the groundwater plume management considers the relevant
and apprcpriate requirements of SDWA (MCL's) and NPDES for discharge
limits.
Alternative 1 would not attain NPDES standards or the SDWA requirements
of MCL's.
Th~ Groundwater Plume Management selected alternative will reduce the
mobility toxicity and volume of contaminated grounwater by pumping and
treating contaminated groundwater.
Alternative 1 would reduce the volume
but not the toxicity.
Alternative 3 would reduce none.
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THE SELECTED ALTERNATIVE
Drum Disposal and Ridge Area - Removal On-Site Incineration
$18,250,000
Inert Disposal Area
- Capping
1,161,000
830,000
Grantham South
- Capping
Groundwater Plume
- Pump and Treat
4.753.000
$24,994,000
The selected alternative meets the goals and objectives for remediation of
this site.
NC5007
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-
APPENDIX A .
SUMMARY OF ANALYTICAL DATA
-------
Table 5.11
Inorganic Analytical Results of April, 1986
Delaware Sand and Gravel Landfill RI/FS Surface Soil Sampling
1,1
t
>*tllM *-
MlMli! iHitllr tauiM
l*f Uli
IKv**l| •<* wtlli lifllH M u«ll*t
crltarl* «rt Ml •(
l*|llM lli|l« iM»U M
Irw
-------
Table 5.12
Organic Analytical Results of April, 1986
Delaware Sand and Gravel Landfill RI/FS Surface Soil Sampling
(mlcrograms per kilograms)
I !
Ittlll INrmt 1 MkflMt M
Hit HMMwil CklirlM fcrtw*
Ml 1 1 1 IN (II
Mil 1 U 1 (1 (IS
Hi: ; i : a gs
Mil 1 1 1 N SI M
MM 1 1 1 N UN
^li I n i N ll M
MM 1 1 M hM
MM 1 1 N IM M
MM 1X1 M ISM
Mil III M (II
MM (41 N ISM
MM S.1II M (II
Mil i II 1 N UN
Mil III M 11 N
Till 1 II ""PS Til
Mil 1 IS 1 1 N IN
MM 1 II 1 IN (It
Mh 1 14 1 111 (li
MM 1 » 1 SN (11
Mto 1 n 1 1 N (11
MM 1 11 I IN 4M
I-IM 1 11 1 1 W (II
I-IM 1 li 1 IN (II
Mfc 1 11 1 IN (11
IM 1 II 1 1U (II
Ml I 1 . II 1 N (II
Ml t 1 t 1 N II M
Ml 1 It 1 N (II
MM H Ml N ISM
I-IM il Ul 1 M (II
MM 1 It 1 N MM
Ml 1 II 1 N (It
Ml H 1 N JIM
1-1} i il 1 N (ii
MM 1 II 1 1 N (II
MH 1 II 1 t N (II
MM II 1 IN (It
I-IM 1 1 1 i N (II
MS 1 II 1 IN (II
1-14 1 1 1 In (||
Ml 1 1 1 1 N (II
1,1 V Mllll IMllN l-r MMllM ll
t- Ifl-
ttMM ckltrr
(•II llkMt
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(IS IM
II S J .
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(U (4
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(II (1
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III (S
(It (!*"
(It (4
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(li (I
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(11 1 N
(1 1 M
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(11 (4
(II (4
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(II (S
(II (1
(14 (1
J' i?
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m (4
(li (4
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it Iff III 'f Mil
l-M«k,l
1-tMlM*
liiKi
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di
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di
di
di
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M 1-
ktltlMI
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(11
(II
(II
(II
(II
(II
(li
di
di
di
di
di
di
di
ill
di
di
di
(ii
di
di
di
di
di
(14
M
(It
(11
(II
(II
(II
(11
(II
(II
(II
(II
1 1-1- MM
ikltrt-
Hlnt
(••••• 99 ••
(S
M
(1
it
(4
(4
(4
(1
(1
(4
(4
(1
(1
(1
(1
it
(1
it
(1
(4
(4
it
(4
(1
(1
(1
it
(4
(4
(4
(1
(S
(1
(1
(4
IN lilvi
tllMM
(S
IN
IN
it
N
M
N
M
(4
it
it
<|
(|
it
IN
it
(4
(4
(4
it
(i
i?
IN
1 N
(4
(4
(«J
(4
(4
(4
III Mil
KM
Mtint
(S
(1
(1
it
(1
(4
(4
(1
(1
(1
it
(1
(1
(1
(1
(1
it
(1
(1
(1
(1
(1
(1
it
(4
(1
(1
1 t
it
(4
(4
(4
(4
(S
(4
(1
U
ItlMttll
lltll
IflMM
(S
M
(1
(1
II
(4
II
S
11
(1
(1
it
it
(4
(4
(4
(4
(1
(4
it
(4
(4
(4
it
(4
(1
i?
it
(1
(1
(1
(1
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(1
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I iMlltf
llftMlM*
(iiit
(IMM
(IMM
(IMM
(}IMI
-------
Delaware
Table 5.12 (cont'd)
Organic Analytical Results of April. 1986
Sand and Gravel Landfill RIIFS Surface Soil Sampling
(micrograms per kilogram)
----------...----------
I I . ". ,
, ...,1- I"'" .- . ..,,,.. '1,'- ,
I"". n.- "'('- ..,n ....- ~- ::f'.- ""r fO- fa. ....t., ..,. "I,.....,
, ".. '.I~ Pyr. ..... .t. ,......,.. . .,..,.. c"" '154 12.. ...... 'If. 1- It.. .
Il T I ----....-----.................................-.---.......- ---I
. HI I CIN CIN m.. m.. u.. ml u" u... IS'" m.. m.. m.. -
-------
of ;
.. . Table 5. 14
Inorganic Analytical Results of February/Karch. 1985
Delaware Sand and Gravel Landfill Rl/FS Soil Boring Sampling
(1n 8!crogra.s per gra. unless otherwise noted)
-------------------------------------------------------------------------------------------------------------------------------------------------------------------
I I Suo 1 -..t, 1 1.1 Ihrc.t I :
I .... I I. I tft.1 I ....114 I IIIhh... 1 FI III tr" II " 1:. lit .. h I. Ii 1:. 1:. II V .. n I:D II .8 lit I
1-""'...--------------------------------------------------------------------------------------------1
ll11t-I'1 "I 1 20-22 1 t. I ".2 1 "522 ".82 UO <10 ..... 51.78 UO <0.4 <1 (0.5 21.35 .. I' I' .. II .. .. IIA .. IIA .. I
I 1 5'1 1 20-22 1 I: 1 15.5 1 11:301 '2.21 (10 (10 25.64 24." (10 (0.4 (1 (0.' 21.60 I' I' I' I' I' I' I' I' .1 .. II 1
1 1 520 : .0-.2 I .up 1 I'.' : 3,OJ2 31.22 (10 (10 13.31 (10.00 (10 (0.4 (3 (0.5 12.42 II I' I' .. .. I' I' I. II I' I' 1
I 1 531 I 150-1'2 I lUP I 1'.1 1 2,068 31.13 (10 (10 10.54 (10.00 (10 (0.4 (3 (0.5 11.4' I' II I' .. II I' .. .. II .. .. I
1--------------------------------------------------------------------------------,---------------------------------------------------------------------------------
ID&I:-2'1 112 1 55-51 1 ,UP I 21.1 1 2,411 21.04 (10 (10 (10.00 (10.00 (10 (0.4 (3 (0.5 16.02 11.02 II I' .. I' I' II .. .. .. I' 1
I I 114 I 6,.61 I .UP I 15.1 I 2,402 4'.13 (10 (10 (10.00 (10.00 (10 (0.4 (] (0.5 11.78 12.76 I' I' I' I' I' I' I' I' I' I' I
I I 5251 1 120-122 I IUP I 16.1 I 1.' 10.'2 (10 (10 (10.00 <10.00 (10 (0.4 (] (0.' (10.00 11.'2 I' I' .. I' .. II .. I' I' I' I
I------!_!~~_!.!!!:!~~.!.--~~.--!..!~:!._!----!!!_..!~:!!_.~!!_-~!!.~!!:!!..~!!:!!.~!!..~!:!_-~~_.~!:~..!!!:!!--!!:!!._~~._~~.~~.-~~.~~--~~-~.~--~~~-I .
IDIC-]'I Sill I SO-52 I UPec I I'.' 1 1,124 14." (10 (10 10.99 <10.00 (It (0.4 (] (0.' 14.99 I' II II I' .. IIA I' II I' II II I
1 1 Sill 1 So-'2 I UPec I 11.6 1 4,415 11.20 (10 (18 1'.IJ (10.00 (10 (0.4 (] (0.5 10.11 I' II II II I' IIA II IIA I' .. I' I
I I 111 I '0-62 I .UP I 21.J I 1 0'6 10.11 <10 <10 <10.00 21.08 <10 <0.4 <1 <0.5 15.72 II II I' I' I' .. II I' I' .. II I
I I 122 I 105-IOJ I IUP 1 11.5 I 1:111 <10.00 (18 (10 <10.00 (10.08 (10 (0.4 <3 (0.5 (10.00 II II I' II I' .. II IA .. II .. I
-------------------------------------------------------------------------------------------------------------------------------------------------------------------
I "'Iic.t. ".11'" .
II S..,I, lOt ".'114 'ar t'l. ,...tlf,
I: 1:01"'1. farllt . : .
UPcc u"., 'otll.t cIII..II, cl.,
utf ~P" Up,., 'Dtouc M.Ylrolltic I.,
ltf 10111t u"., ,.tllac 1I,.rlll,l, J.I
-------
Inorganic
Delaware Sand
Table 5.15
Analytical Results of February/March.
and Gravel Landfill RI/FS Soil Boring
(milligrams per kilogram)
1986
Sampling
.
, '...., ..... , ... he'" I
, 1111 I , I , IIU '...... ''''IbrI' . . II II II fI ~ rr CI r. F, .. .. II .. . . It.. II n .. , II'
,------ ----- , ------- - I
,-... '''''' ,.. , I, SJ.I I.'" C8 1.1 ,.. U C1.8 ne I'" II (II ..... '.1 '268 .. CI." It m n.1 CU (18. cu CJ8 '81 t2,
,.... 'I-l' ,I-" , ,..., SM88 m '1.1 iii cu U.I .. ..1 I' US mM 11.1 '4" ,... CI." 21 511 CI'I CI.I eme (1.8 en '1 It,
I === I 1:1111 II:B 1 I 1":1'1 !!! :19& :::& m :I:' u:l:m I::: m :::: r.= :J : It :::11' :III m: U:I U:& m: :u m (f, C::., I
,.... I f., I Jl-n , , ,. rn; C c,., CI9 II.' 11.1 m, ,., III Ct.J '41. I.t, tIS 'II CI.' II II" U. 84.1 IISM CJ.I Cli ur \I I
I.... 'I"t' ." I 8'tc , 'I. 'I'" c, CU ctI CI.I CU. .., III ... ml 1.1' mi.' CI.' m III CI.I CU 116M CJ.' en II
-------
Table 5.16
Organic Analytical Results of February/March 1986
Delaware Sand and Gravel Landfill RI/FS Soil Boring Sanpllng
(mlcrograms per kilogram)
1 t 1
1 1
lit- III
1 1 1 IhrCMt 1 t-Mtkyl- 1.1- I.I.I- 11-cMvt 1- 1- 111- llttkfl
Ml llwjltl h-lk 1 IIM Itolttvll Mkfltw t-MMMt l-»MtiMM lUfl ttttl lUiltrt trltiltrt ttkyll «4kTl Mtkfl ktlil Mirll MMMc taut
MMfr llMkrl till lltMltJ 1 III 1 MMM CMirIM KttMt UUI MINI IMIM* I|I*M itk*M &!*«(«* rikM* AM*! itktr BMM! yktMl fklMlat* |ktkil*lt MrttaltM Mil wtkricM*
MC-M .1
MC-M t
NC-M 1
NC-M 1
NC-M 1
MC-M 1
MC-M
MC-M
MC-M 1
MC-M 1
MC-M
Mt-M
82
Kg
MC-MH
NC-MH
MC-M
MC-M
MC-M
NC-M
MC-M
MC-M
MM)
MC-«
MC-I
MC-«
MM
MC-«
MC-I
MM
MC-I
MC-I
MC-I
MBF.J
83
NC-4
1 Mt-4
Mt-4
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1 1
•1
II
1
1
g"*M 1
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183!
84
|MC*M_
k
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1 MC-I
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1
1 MC-M 1
1 MC-M II
1 MC-M H
IMC-M 1
IMC-M 1
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M
1
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-111-411
-Ill-Ill
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(if
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41.1 U.I (4.1
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V.III 111! 411 411 (1.1 (4.1 U.I
•f" fit *il I! <»•• «••• «••
r n\ Mr IM (it (i; IN
r KM IIM IIM MI m INI
II IfM IN* lit* (41 (41 (41
? I
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II MM IIM I MI4 (M (M I44B
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41.1 (I. M MMMMMMM
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(1.1 (1.1 (4M (4M (4M (4M III U (141 (4M (INI (IM
(1.1 (1.1 MMMMM M MMM
(4.1 (4.1 (4M (Ml (Ml (4M Mil 4M U (4M (MM (*M
(M (If (MM! 41MM 4MMI (144M MM! B M4M II 4JM 1 4IIMM (MJM
So iii 'ii* i" (2* B*J *3*j 1SJ v **$? (2*
U.I 41.1 I4M IM (Ml INI Hill IMI (Ml (MM (Ml
U.I (1.1 )IM ill (IN 4111 MM 3 1NU (IN (MM (IN
411 411 M, M M M M M MMM
U.I (I.I M M M M M M M M £
(1.1 (I.I MMMMM M MMM
(1.1 411 MMMMM M MMM
(4.1 (4.1 MMMMM M MMM
(I.I (1.1 MMMMM M MMM
(1.1 (1.1 MMMMM M MMM
(1 (1.1 (4M 44M (4M 44M 4M H W* U 4444 (INI (441
44. U.I (IN (Ml (Ml (IM MtB Ml 3 (Ml (MM (Ml
(4.1 (4.1 (*M («M 44M (4M IN B 4M II 44M 414M (4M
(1. (1.1 (4M (4M («M (4M 1MU Mill (4M (I4M 44M t
(I. (1.1 MMMMM M MMM?
(4.1 (4. MMMMM M MMMI
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(1.1 14.1 MMMMM M MMM
41.1 U. MMMMM M MMM.
(4.1 (4. MMMMM M MMM
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(1.1 (11 MMMMM M MMM
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(4.1 (1.1 MMMMM M MMM
U.I U.I MMMM M M M'M M
(|.i (I.I MMMMM M MMM
(II (Ii M M M M M M MMM
(M (M (4M IMI IN INI IfM II III II (4M (MM (4M
(II (II (Ml (IM INI (Ml 1MB 1MII (Ml (MM (Ml
(If (M MMMMM M MMM
(11 (11 M M M M M M MMM
(If (If IN (4M IMI (4M MM II 4M II 44M (14M (4M
(11 (11 I4M I IM 1 I4M IM 1 (IN IIM II JM 1 (MM (IN
(1. (1.1 (4M (Mt (4M (4M 14M II Ml B (4M (MM (4M
U. U.I MMMMM M MMM
(» (M MMMMM M MMM
(4. (4.1 (IM (Ml (Ml (Ml fM U Ml II (Ml (MM (Ml
(4. U.I (IN (IN (IN (IN 14MU IN S (IN (MM '(IN
(II (11 M M M M M M MMM
(1. (11 MMMMM M MM.M
(1. '(I.I MMMMM M MMM
(4. U.I MMMMM M MMM
(ll (11 M M M M M M MMM
(IfilfUMMMM M MMM
U.I ' (4.1 MMMMM M MMM
• I MMMlflTMtlM ,
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-------
....--........-........-....-.-...--...-......--.....-------...-----...---.....--...-....-------------.......-......-----..-....---------..---
Tabl. 5.16 (continued)
Orlanic Analytical Reaulta of February/Marcb 1986
Delaware Sand and Gravel Landfill Rt/FS Sol~ Borina Sa8Plina
(alcrolra.. per kilolraa)
. . . . . . , .......
I ;"11 1.....1.... I... 1=='1' "''''''' I-W- I=~ I'", ,.... ..:,1;,. ,:,:&1;" '~:Ir"...t. ...~, e;--I' 't::tr' ""'1 ....,
I "'r. I....,. flU ''''''III''U ,..- D'ir'" Ir"- .... 11... "'.- 1,,- et... Qt.,... .,.... ...., .,.. ...... ...... fII'" eta fII,...1te .......- K" .'''8,;11/"
I.""'''''''''''''---''''''''..-_.'''-~--,,--- -----....-..-... ...--......--....---........--..--..........-....-.....-..-........--....-...........-..-.....---..---..---..--------........-. i
I -.., . I-I' "I . I, II C"I Cf'l 1111 CII en cr.' cr.' cr.' cr.' cr.' . . . . . . . . . j
. .-8J 'I- . tor, ,. C . C . ." II us Cli CU cr.' cr.' cr.' cr.' . . . . . . . . III I
U~1: 1'1:' " I~i" I I U:I Ct'L ft ~ :IIi ~I, ~::: :::: :::: :::: U:: c~ c~ cra c~ .:. II c:-a c:l. c:. c:-a ;
,.-1' ,-s It-, ~ U. 1 II .. II U UJ cu cu cu cu cu c. c. c. c. ISM II . II C. CM c. !
I =~: II~ 'I It 1 I ': :t : II g ~ u m :t:: :::: :::: :::: :t:: c:' c:' c:' c:. :. II :. II c:' c:' ce.
,_.., 'H ;: , "I . C 1 I ~ II en m cu cu ..., cu cu . . . . . . . . .
,--., ,a.. , .'J ,8Itc , I I, c . . II II UI CU cu cu cu cu . . . . . . . . .
,_.., '1-1"'" 8U ., c. CA.I C II U ..., CU CA.' eu cu . . . . . . . . ..
,--., i-'l'. ... 18 J.. B II II CU CU CA.' cu ".1 . . .. . . . . . .
, -.., -, .. . . C II U U "'1 cu eu "'1 cu . . . . . . . . .
-.., -', .. C . . . C, ct. !t-' Ct.. !t. ct., . . . . . . . . t
1 -i::J : III , A :: : ~ ~ III !!! eu" U: :11 U: :11' u: :m :m :m := 1= I C= II := m: : 28
I :1' .111 :I: 1 . .,. 8M ci:1 It:1 U:I - U:I U:I I I I: I I: I: I: I: .
I I~J 1 -I I :: :1 :~I .. :II UI :'11 U: :1: U:I U:: :t:: :: :: :: :: :: :: :: :: :: i
I i~f I H 1..111' i I': ~ ... CI II i'll il U:I U:! ih it:! it:! 5 5 5 5 5 5 5 5 5 i
! a~I,1 :D IliliJ I = 11,1. ~I 'tl. :0- :1' iil U:! U:! it:! it:! U:: 5 5 5 55! 5 5 5 1,1
, -.., . -M Ili'u ' "* .. C"I '1:' UI U U ...t .... ".1 cu cu . . . . . . . . . .
i ii ;11 11'1' =1: 'iltl i~1 ~II' i ;'1' II 1',' it irl' ~U ii~11 ~i iU 5 5 5 5 5 5 5 5 5 I
, =.., - II '8' I: u: Ct C I C CII Ct u:1'" "'1 "'1 . . . . .. . . . . I
I.. .., , .. , ..!-_'!.-.!.. C C C c.. ~~_.~ . . . ~ . . ~. ,-_I
,_.., 'tJ 1 I, I'" ',.. ... . i" m m .... cu .... .. . .... . . . . . . . . .. i
I Si =I - I ,Er, i 'll'III' :11 t Iii .£. ill U! U:! il:l ii:1 !!~, :u il! ill i!! il! cj! J :a I 1ii iE! im IIi
'-== I 'JU ... I' is .J II UI CI' CI" u:,; CI' CII :1':: «lit cm cm mt . It «lit U.. CJIt
! S== I - I ~B I. i~, I ~I t~1I I:t i! . hi is:' :1: id : :f i :, 5 E E E 5 5 5' E :.1
11:1 I ..I ~ I:: I,EII I: I I ~ '.1'. U CIJ :t:1 ".t :t:1 :::i :1:1 e:' cft. cft. c:' ft. , 'A' cft. clft. c:a. l
'-! '1-11' .11 '..c , "'I'~ J.I II i' . U :111 "'j :::1 ... ... ".1 . . . . . . . . .'~
,- ,I- I SJ I . 'H' I ., II~ II U U cs. ct. cs. cs. clot . . . . . . . . .. I
I I:.. -I I :t :: I': .,. II :I U U U: :::! :::1 :::1 :t:1 :: :: :: :: :: :: :: :: :: 'I
'.1'1' .,1. c"ll" '" U CIJ e,. .. CA. .., CA. . . . . . . . . .
, - ,IS- . It.' c.. 'r II B c' UI "'1 ":1 "'1 ":1 "'1 . . . . . . . . .,
. - I Ii II. C~ . i & c, U ... ... C,. c.. ... . . . . . . . . ..
I - . I f". U U ct. ct. C . CI. CS. . . . . . . . . . ,
- So C 'U U cS.1 ct. (.1 CI. ct.' . . . . . . . . . !
I I... 1 III'" t c, ,'L ft II :J' :: :I:. :::1 :s:, :::. :::: :: :: :: :: :: :: :: :: :: I
I 1:= I -II, 1::1:',' I: : 1 c:t. 11111 z: u :8 :II cu.. cII... c:l.. C:I.' ~u.. :: :: :: :: :: :: :: :: .:: I
,.... . II, 'I-'t!' ,. , ,. e, 1111 1tt e cs..., U Clt ca caa . . . . . . . . . I
I::: I t.ft III::IB I :: I It., ,:1:' 'II ~:: HI :If :U :I:' : :1 :1" :U . =. :: :: :: :: :: :: :: .:
,.... '1-1" n"'D' lit , ,.., 'clot, II nt ca CIJ es.' ct.. CS. ct.. cs.' . . . . . . . . ..
...----..,
-....----..---
..---
--------
-.........----
t
.
~-
"'Ure', .......
j~l. lit ."1.,.111 .. W. c...,...
"" ..., flcell.
-.t ... .....'111 ... ... 'I .... ~ c.clltlat'.. I. CIIf'" U. ,,-..
...,.. ...1It, ... ...111, c.'"1 crU.I. .t - ... .
~ r..a"'t ,...... .
IPrI ..,., ht- ..UI!" cI.,
,. ....... ht- """"'1 1-
"* -- Pil- '''1''..- cI~
,., ,-... ..,- .,.",,,11 I..
IPI .."" Pit- EI., .
-------
4-Mtftfl-
t-MMMt l-HltM
JM IKII III*)
(SI
Table 5.16 (continued)
Organic Analytical Results of February/March 1986
Delaware Sand and Gravel Landfill RI/FS Soil Boring Sampling
(mlcrograma per kilogram)
„
tltll
IflMt
(SI
(it
i!i
(i
(i
(i
(I!
(I
(i:
(i
(ii
(U
ii!
(i:
58 %
<» "•
(i.l
(i.f
(i
(i
(i
I
(l
(i:
i!
(i:
(i:
(IS
(i.i
(S.I
(S.{
(s!<
(S.I
(S.I
(S.
(S.
({,'
d.i
(M
(I.I
d.i
(it*
(ii
(fr1
?f
i!
(i.i
(4.1
(4.1
(4.1
(If
(IS
i!
at
(S.4
(S.I
ai
(II
ii!t
(if
d.i
(»
a.
i]|'(
«if'
ft
(M
(I
(4.
(I.
l.t-
Mciltrt
HkaM
_._„
(»
ll
(IS
(4.1
(S.I
(S.I
(S.t
(S.4
(S.I
(S.I
(S.I
(»!i
(if
(4.1
(M
id
(I
'('.,
(I
(L«
CMvijIm
1
'ill
(IS
I.I.I-
trlctlvi
ilkiM Mml
(I.I
(1.1
(S.I
(14
<»•!
<4.l
(I.t
(S.I
ill
(II
(If
(it'1
iit'
(4.1
(It
(14
(14
(If'
it;
(4.1
(411
(H
UKMtrillM U ttrflrt III prtMCt.
IttlMti) fMrtlli tacMt «ulllr ttrtrfi trllirlt mn Mt MC.
PrflltlMrfi II Mt CMlMiMtlw iriclrfM MtHrMtlw tt CMpM* pmiKt v
f Mrtkli NrMllii
Vcc ttt* MMK caHilM cli*
-V mpt *MT MMK Mr»l4lc !•
V* $HT MMK IM4l-« cl*f
IV IMT (MrAfrit ir«rtlt|lc !•
-------
Table 5.17
Inorganic Analytical Results for Surface Water
iMlftlcil *MlU H toll
IM* »H *rml llfft
III
1 iMfll
jUttllM IfM iMfMMI ttTMlM MltV IlK UM tlMM ferCVf
II *.4f) I.IM (MM (I.IM II.IM II.IM II.IM (I.MI
II MM MM (C M (MM (I.IM (I.IM (I.IM (I.MI
il.JJJ l.m (». M ((.IN (I.IM (I.IM (I.IM (I.MI
.III MM 1) 11
I.M (M 1 (Ml II.) 4t ()
l.ll 4.1 11 I.D llt.l Ml M
II. *Mfl. M.-T IMII. Mill Tl. HI- 1^..
M M • M • M •
M M M M « M »
• M M M) M M Ml
8 8 B 8 8 B B 1
\ m m m m m m m
-
'
fctWUll llMlIt *
MMT* bM *t fcml llffl hrlm klv |M«||«| III
llMflll
lUMlltil lr«
Mcltl
wf 1MH« dtall Tit M«!MI
— —
1
1
1
I.I
1.
1.
(1.
<<:
1.
t
«
I
1
1
1
1
1
1
1
1
tl
.in ii.ui
.111 11.11!
.IN 11.11
.Ml 11.11
.U (l.ll
.144 (l.ll
(11.111 11.11
11.111 IMI
l.lll 11.11
(Mil (i.n
(Mil (I.I
(l.lll (I.I
(l.lll (I.I
(l.ijl (i.i
(l.ll* (1.11
(Mil (1.1
(i.iti i.«
(Mil l.ll
1 (Mil (I.M) (I.MI (l.lll (I.M9 (MB II.MI (I.M) (1.491 (I.IM (l.lll (I.IM (I.IM (I.M* S.IM
(Mil (I.MS II.MI 11.41* II.IM
(l.lll (I.MJ i.Wi (Mil (I.M9
(l.lll (l.iM II.MI ll.lll (l.4«
(l.lll (I.M (I.MJ (l.lll (I.MI
(Mil (I.M I.Mt (l.lll (I.M
(Ml* (I.M) (I.MI (l.ll* (I.M
ll.lll (I.MJ (I.MI (l.lll (I.MI
(Mil (I.M) II.MI (Mil (I.MI
(Ml) (I.4M (I.M) (I.IM (I.IM (Mil (I.IM (I.M* (I.IM
(MM (MM (I.M) (I.IM (4.1*1 (Ml* (I.IM (I.M* (I.H*
11.11) (».*M (1
(MM (».IM (1
(l.lH (I.IM (1
(Ml) (I.MI (1
(l.tl) (I.M* (1
(Ml) . (I.MI (1
I.MI
.M
I.M
I.M
I.M
>.M
(*.*M (MM (l.lll (*.»» (1.441 (I.IM (!
(I.M* K.4M (l.lll (I.IM (I.IM (I.M* (
(I.IM (I.M* (1.414 (MM (1.441 (I.Mt
(•.•M (».«M (Mil (I.4M (I.IM (I.IM C
(MM (I.M* (4.414 (I.4M (I.IM (I.IM (
(I.IM (I.M* (Mil (I.IM (1.441 (I.IM 1
.m
.IM
.M*
.4M
.«*
.M*
.M*
.IM
. frlf (TMl, M tt iHll II
. *rif Crtrt CM( *l tail 11,
riKt
%ftr*M tl Mr
«t»,
I. Irtf &M4, Mv lallrtil trl«|f
L Ir^r Crtrt, N«U ItU, tot iTlMto f
T. l/Mtl nitmt
*. UttrKtlMl It/M IM« 4f Nil
Nr tMl *****
M IM.I* M( MMlriM ta
III toll* It M* !•(•»! ff
-------
fable 5.18
Inorganic Analytical Results for Stream Sediments
I MMll
lUCltlM
H
u
IfM
»*••«•«
If.Wt
1:8
44,*ll
4F.M
M.M
H.*
:
M
71*
Ml
(MTMtU fculHICll fcNltl tl iKlt IW
hM u* Irml IM4IIII ll/fl MrtM M!IM(
IU ilcr^trtM >«r
III
•muni CfeMlM Nlw tlK IM* CMMM «rt»r trwU MM!M MT!M CMMT CalclM Hctol
tMlIlM CMdl Til MMtM MMMlM
II. M
11.1
u-[
n.i
n.n u.Ji
-------
Table 5.22
Inorganic Analytical Results of April, 1986
Delaware Sand and Gravel Landfill RI/FS Groundwater Sampling
(mlcrograms per liter)
I Mil I I l«k I M B • It to U U
to
ft
II
i*
8!5i
4)1 (
tc
(U
KM
411
411
411
411
411
IS!
a
8
ii
(I.I (II IIM I (II
(I.I (II MM I (II
(I.I (1.1 IMM (4.
(I.I (1.1 till I (1
(1.1 (I.I UM (I.
. (1.4 (4.1 UN (I.
II (I. I (1.1 ItM (I.
I Mt-1 I I
I MC-I I I
iBflili
I (It (ft 411 II (I.I 411 IIM J (1 (I.I t.l U
j 411 (M 411 M (I.I (II UM I (1 (I.I I.t U
i'UVH BttlWW'il: IHl!1"
I (It (U 411 n 41.1 (II MN I t. (I.I II U
i at i
iat i m
i at i
i at i
i at t
i M
IM
i—
I Mt-411
I KC-llt
I MMM
I Mt-lh »l I* I
I Nt-lh tl Ot I
I MC-tll I Ot I
I MC-lk I Ot I
i MC-M 11 at i
i MC-M 11 at i
I Mt-49 I at I
i Mt-M 11 at i
I Mt-M t I U I
i Mt-iii i at
IMt-OIt
I MC-M4
I Mt-Mt
i Mc-m i at i
i Nt-Mt ti at i
i Nt-it* ti at i
!S:!S^!
I Mt-lll
I Mt-IN
"(it
(n
(ii
Ml
II
IB!
i at i
i MC-I
ir~ '
I M-ll I
I M-ll t
-tit i at
•u i u
i at
i at i
at i
i
Ml (U
in (it
II (U
M (1
Mdl
(It (M
Mm
M(U
(Hilt
a (11
M (S
M(M
M(U
(It (It
(It (II
(If (H
11(11
(lt(H
111 (It
(HOI
44 (n
(It (It
Mdt
(1
(II U
(II III
411
II
M
(II 111
(II
. M
(II IIM
(II lit
(II Mt
(II Ut
(II Ml
(1 M
(II n
411 111
(II 111
(II tit
(II M
(II III
III if
(II ItM
(II 111
(II 111
(II M
(II 111
I M
(I.I (II IIM I t,
(I.I (I.I UN (I.
(I.I (II I MM I
(I.I (II IIMI 1
(I.I (II IIM I
(M (l.l M
(I.I (II HIM
(I.I (1.1 till !
(I.I (1.1 IMM
(I.I (J.I MM!
(I.I (J.I HIM
(I.I (I.I MM
(I.I (II IltM
(1.1 (I.S M
(I.I (II MM I i
O.I (II MIM
(I.I (II UN I
(I.I (II HIM I <
(I.IXII IMM!
(I.I (II IIMI I
(I.I (II IJIM I
(I.I (I.I IJIIM
(I.I (I.I IIII
(1.1 (4.1 IUM
(I.I (II ItM I
(I.I (II ««M !
l.l (I.I M
(I.I
(I.I
(I.I
(I.I
-------
Organic
Delaware Sand and
Table 5.23
Analytical Results of April, 1986
Gravel Landfill RIfFS Groundwater
(micrograms per liter)
Sampling
.........--..-----------..----------------.-------...-------.-------------------------------.----------------------- ..----------
I I I ... 6...,.. .-...,1 2- I
I I I I ,- 2- ',2- 12-'''rl 12-c'1., c.... 2- .",1 1
, I I .dl., ...... IIc.I., ..." ,...1 ...,1 .",11 .",1.. .n.. "Ir' ,..,..... ,....1 I
I ..... '~I"'....... I'" ..... "'1111 .,1- ,.".ht. "'1" t.,- I'" c..... 11£1. c'I.. III.' 1e-c'",11 I
1----- --..-------- -- ---..---------- -e. ---- ------..---------------- --- ---- ------------..------....---------- ------1
I S. I ell I III IS . III ., IS , , , III IS , , III IS . 15 U' U' U' I
1 2. I ell I '" 15 II III IS IS 15... IS IS U' 2 III IS U' II' U' I
I n I I: I g Ii .. III (S (S IS . III ., (S III (S ., U, U8 II' I
1 ., I I.. ( II ., IS , ,.. . III , - ... (S 2 'U. , , II I
I . , I II ( . III (S (S ., U II IS ., J ,(S (S U8 I II U. I
I .. , ell, J II (S .. III (S IS (S . III (S IS III ., , , , 'U. U. I
, U I ai, . II es II III es. IS es 2J III (S ., CII 2 III ,.. III U. ell I
1- ------------------------..----.--------..-----------------------1
'.-2 I aI I J II el II II ., (I (S U. el el u. U (I Cli u. CII I
'.-J I all II e , III C) e es elt e ( UI cell ell ell
. .-11. .. e e (M e ( III 12. e e e e e ( (
I .-IJ . . ell I '" es II II es es es CII es IS CI. eS es CI. CI. "I'
. .-11 . I all II III e. , II es es e, Cli ., es III es IS Cli ell "I I
,----------------------------....---..------------..---------------,
, ... . ell. '" el II II es es (S UI (S (S Cli '" (S CII (II UI I
I H . ell I III , es U II (I (I . , . II , , , , U8 II II (S CI. , , CI. .
.-------------------------------------..-----------------------1
. lie.... 'al I J III (S , III (S es (S Sill., IS U8 ., es "I III "I'
. ..... I ell I . III es , III (, II . , Jiles (S . , I III IS UI UI III'
... I ell 1 U., (S .. ., IS , , . , I III , U "I IS e, CII II' CII.
. ...h '1 ell II'" III (211 .... III (211 I'" ,.. 2 III ... ,... JIt (211 (211 (SIt JIt , 2S I
. .-th .. U Ill.. c. t2t 21 ,.. ... e21 '" S2tt '" (M (. e21 UI .
I ...,. I ell. .., e, U III es , , . , , ., (S (S III (S (S "I . , (II I
I S"Je I UP IISIt III (211 1M III I" , ... II" II ., IS' .... 22t e211 (211 eSlt IS' JIt I
I -It . I UP IISIt II e211 ,... III (1St 22t, ,... U II ISIt .... I'" U'" (211 eSlt SIt . II I
, -It . , aI "* II e211 ,... III (1St 218 "" I III ISIt I'" ,.. ,.... e211 e* SIt "I
,...., ,UP, 52 III 2 , II II , , S I 2t 2 III II II III (S (S CII Cli (II I
I ..... . I aI 11211 II (211 '*" (211 218 I JIt , III It I 2* SS It III e211 eSlt (SIt J' I
I ..... . 'U 11* (.. '" eM 1St III e21 "U88 St etlt eM eM 211 I
I ...,. I UP I 2S III II It " e, es , , tiles es "' , II IS CII Cli III'
I ...,. I aI I Utll cSt "' III It , 1M 2It ""...... SA cSt 118 II , IS , III I
I lie.... I aI. . III el I II el (I 2 , 2 III el eS Cli 2 III eS ell Cli CII I
I."" I C1P I n III cIS sr II cIS ,. ,.. . III ... Jtt 2M CIS CD C. cSt U. I
'.-ttc I UP I. I II el . II IS es es ell IS IS CII IS el CI. "' CII I
I lie"" '11" .. III e' . III II CI e' " " e, IS CII , III e, CII Cli UI.
I ..... '1 aI , .re IS n , e, II 21 , II II II " I III es CII II U. I
, ..... .1 UP . 'St el "' , e, I II CII II IS CII 2., e, CII I I ell .
I 1Ie-'" I UP I I' III e' II III e, c, J , Sill eS 2 , Ctl cS e, CI. ... ell I
I 1Ie-lh I ell I 121' IS I III es es e' Ctl e, IS ell 2 III " Ctl UI ell I
I lie-II' I UP I . III es I III e, IS e, J " e, IS ell e, C, ell (II U. I
I lie-II. 111' I IS III el , III es IS e, CII IS es ell I' e, UI III ell I
I 1Ie-'H 11111 '" (S 1111 eS e, e, Ctl e, IS UI 2 III e, ell ell UI I
I 1Ie-'h 1111 I "" es n III e, es e, . III IS es UI I., es ell (II (II I
I .-n . I 111' '" el II II eS es I' U. e, e, Cli 2 III es III Cli ClI'
1 lIe-n . I Ii I eM e2 e21 e2 (2 CII c. C2 (2 e2 e21 C2 II ell - I
I. ----------.-------..----..- --------- ------- .---..- - -- -------- ---..--.---..-----------..... ---"-------"--"'----------"--------1
I .-11' . UP I . III e, S III e, I' e, I " e, IS CII (S e, CII UI (II I
I .-11' 1111", III e, (II e, IS IS..I I' e, CII I .,. IS CII "I "' I
I .-11 I 11' I I III IS . III (S IS IS , III IS IS . 'es I' CII ell ... 1
'.-12 . Ct., I .11 IS 11111 e' es e, ell , S II e, (S ell II' (II I
I ..n I a.r. ..., e, II III IS "St 2 III It (, . , es . e, UI I ~ CII I
I.-It I 1111 . III e, U III IS I' es 2 III e, IS "I' J III (, ell ... CII I
. n I Ct.,. , II 2 , , II IS (S (, J III I 'eS ..J IS e, CII e II "I I
I 21 I W 1 I III I' , III e, e, (, ell J , IS . It ., e, e, u. (II (II I
I 2t I a.r I I III 2 , , III 2 I . , es CII . oJ, II e, 2 I CII e.1 ... I
. II . . W I II III e, , III e, II It J".. . ,... ". e, ~ IS (II . ~ ., I
I II . 1 Ii I eM e2 (. II I 8J e2t »1...... II' e21 e2 II ell 1
-.-.--....--------.-------...-------.-...--....-------......_---------_.__.~._..._...._-_.._._--_._--_.-.._-_..._-------
. '-lIc", ."''"
- "'I,lInl .... II lit ...11.....
, 1111..... ..,..It, AIC... ,,'''h c..,11 C,It.'8 ..... lit lit.
, ".118""'1 II... CII'.'"IIII "tel... cIIII,..1I1I .f C..,... "..... ... ....11',.
., . c..,... ... .'lCt.. ... .It I. 'I" ...... Cllelltrlll... II ellfln III "IIIIC',
-------
Table 5.23 (cont'd)
Organic Analytical Results of April, 1986
Delaware Sand and Gravel Landfill RI/FS Groundwater Sampling
(rolcrograms per liter)
" 'S
*
1 1 tit 1,2- 1,4-
j 1 M|l llcklwi cklv* tlcklwk
Ml 1 i I* IfMkUlU ItkMt kMIM kMIM*
1* 1 Of 1
ft 1 Of 1
» 1 Of 1
31 1 Of 1
U 1 Of 1
S-l IB!
HC-«1 1 1 U 1
M-n 1 1 of i
MC-fl M Of 1
Kl Of 1
i Of 1
Hi-Ill 1 Of 1
S-4II 1 Of 1
-121 1 Of 1
MC-I2I H Of 1
HC-I2I H U 1
MC-IU 1 Of 1
MC-IU 1 Of 1
Nt-M i 1 Of 1
MC-14 l 1 Of 1
Mt-*S (Of 1
MC-4* I 1 Of 1
Nt-«4 • 1 U 1
MC-IU 1 Of 1
MC-lll 1 Of 1
Mt-*M 1 Of 1
Mt-Mi 1 Of 1
MC-Mc 1 Of 1
Mt-*M 1 Of 1
MC-Mi •! Of 1
MC-4* II Of 1
Mt-IM 1 Of 1
MC-lta 1 Of 1
MC-II* 1 Of 1
MC-IU 1 Of 1
MC-IN 1 Of 1
Mt-lh 1 Of 1
Mt-ll • 1 Of 1
MC-II » MI i
M-ll i 1 Of 1
M-ll i 1 Of 1
•-II 1 Of 1
M-12 I Of I
M-ll 1 Of 1
KH4 1 Of 1
11 IOf 1
M I0f 1
2f IOf 1
11 • 1 Of 1
11 • 1 U 1
(II (3 (3 (II
(ii
(3 (!
(3 M*I tkwil
(3
(3
(3
(3
(3
(3
(3
_
(2
(3
(3
(3
(3
...
(3
(3
(231
(21
(3
(231
(231
(21*
(3
(23*
(41
(3
121
(S
(23
(3
(3
(3
(3
(3
(3
(3
(3
ii
(2
(3
(3
(3
(3
. (3
(3
(3
(3
ii
(2
(It
(II
(II
(II
(II
(II
(II
(It
(2
(II
(II
(It
(II
(II
(It
(II
II
1
(II
(M
(M
kl
(II
(II
(2
(II
(II
(It
(II
(II
(II
(II
(II
(It
(II
(It
(II
(II
(II
(II
(1
(II
(II
(II
(II
(II
(II
(II
(II
(II
(II
(2
(It
(II
(It
(It
(II
(II
(II
(II
(t)
(II
(II
(II
(II
(II
(II
(II
(It
((
(n
(3*
11 1
Ikl
(II
(II
(4
(II
(II
(II
(II
(II
(II
(It
(It
(II
(II
(II
(II
(II
(II
(II
(II
(It
(It
(II
(II
(II
(II
(II
(II
(II
1*1 kitt
fail ydui
-------
APPENDIX B
RESPONSIVENESS SUMMARY
-------
XI.
RESPONSIVENESS SUMMARY
As called for in Section 117 of Superfund Amendments and Reauthorization Act
of 1986, DNREC and EPA has presented the proposed plan for public review.
DNREC and EPA accepted written comments on the proposed plan and draft
Remedial Investigation, Feasibility Study until April 18, 1988.
A public
meeting was held on March 16, 1988 at the New Castle DNREC building in New
Castle Delaware to discuss the proposed remedial action directed toward
addressing sources of contamination by removal and on-site incineration as
well as addressing remediation of the groundwater contamination plume.
The Responsiveness Summary details the comments received from interested
citizens during the public comment period.
The discussions answer the most
prevalent concerns expressed by citizens, as well as addressing individual
comments.
Verbatim transcripts of the public meeting, written comments,
meeting notes, telephone memoranda, newspaper accounts, and notes made
following conversations were used when compiling the comments.
Subject:
Groundwater Contamination
1.
A Resident on Route 9 with a private well was concerned about
contamination reaching his well in the future.
EPA/DNREC assured the citizen that the plume should not migrate in
the direction of his residence now or during the remedial action.
Continued monitoring of the plume will occ~r during the.remedial
action.
If contamination moves toward residential wells, those
residential wells would be continually monitored to insure no risk
to those receptors occurs.
-------
2.
New Castle County expressed concerns on how those who read portions
of the RI/FS may make conclusions that contamination (Specifically
l,2-dichloroethane) at AWC-7 is a result of Army Creek Landfill.
DNREC/EPA assured the county that due to insufficient sampling ~nd
analysis that we were not making any conclusions about Army Creek
Landfill.
DS & G Remedial Investigation Executive Summary page 1
states "As indicated by the solute transport modeling, the source of
the 1,2
dichloroethane contamination is not likely DS & G.
The
source is likely west of DS & G, but sampling and analysis was not
sufficient to identify the source of this contamination.
A formal
response to the county was drafted and is attached to this
responsiveness summary.
3.
New Castle County suggested that Delaware Sand and Gravel may
actually be the source of the 1,2 - dichlorethane contamination at
AWC-7.
Although the RI report notes that there was a potential for
DS & G contamination reaching AWC-G3, the observed groundwater
quality data do not support this.
Despite the fact that 1,2
dichloroethane was detected near the DS & G Drum Disposal Area, the
concentration values decrease rapidly moving away from the Area.
Finally, balancing information on observed water quality trends and
historical plume shapes with the simulated flow and traftsport
results simply does not support DS & G as a potential source of
contamination at AWC-7.
4.
New Castle County suggested that other areas may be the source of
the 1,2 dichloroethane contamination at AWC-7.
Evan though not all
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of the listed sources were evaluated, it is felt that none of these
are likely candidates because of the thickness of the clay confining
layer, the distance from AWC-7, or the fact that the contamination
would have to be detected in either AWC-2 or AWC-6 first and this
has not been observed.
The analysis of flow paths, groundwater
quality, and geo1gy suggest that Army Creek. Landfill seems to be the
source of 1,2 dichloroethane contamination prior to 1982, when
additional ~ecove'ry wells were installed.
With the new recovery
wells, potential flow paths from Army Creek Landfill to AWC-7 seem
to have been eliminated and water quality improvements in AWC-7 have
been realized since then.
5.
New Castle County feels that the groundwater modeling in the DS & G
RI/FS is not correct because the model had contamination emanating
from Army Creek Landfill prior to that from DS & G, the model kept
RW-3 in operation for six years after it was shut off, and the model
was not calibrated as rigorously as possible.
For the model, it was assumed that leaching of contaminants and
contaminant migration away from Army Creek Landfill began before DS
& G because wastes were placed there earlier.
Even though the exact
leaching events and pathways are unknown, the "times of initiation"
are not far enough in error to cause a si~nificant change in the
past - 1982 simulated results.
As far as RW-3 is concerned, the
additional pumpage (actually four years, not six) should not
significantly alter the simulation results, eaxcept maybe to enhance
the maintenance of a stronger groundwater divide.
Finally, the
modeling calibration was done in accordance with accepted methods
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Subject:
Subject:
but, due to the extreme complexity of the system and the
simplifications involved in the model, it was not possible to
develop a fully calibrated numerical model capable of matching the
observed heads at all times.
Regardless, the calibration of the
model was sufficient to evaluate the contaminant transport in the
vicinity of DS & G and Army Creek Landfill.
A more rigorous
calibration would not hav~ significantly affected the conclusions
based on the existing simulations.
Surface Debris and Continued Dum?ini
1.
A resident of Grantham lane commented on the surface debris and
continued dumping on the inert area.
EPA/DNREC assured the resident that the surface debris would be
removed during the remedial action.
DNREC's Waste Management
Section is addressing the continued dumping of material in this area.
Incit1eration
1.
A representative of the area expressed concerns about emissions
(chemical and odor) from the stack of the incinerator.
EPA/DNREC assured the public emissions would have to meet stringent
requirements of RCRA and Air Pollution Control Regulations.
In
meeting these requirements emissions and ~dor would be {educed to
minimal amounts which would not be harmful to the public health or
environment.
2.
A representative was concerned with how long the incineration would
take to complete.
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Subject:
EPA/DNREC estimates incineration will take 3 to 5 years.
3.
The question was asked if off-site incineration was considered.
EPA/DNREC did consider off-site incineration; however, the risks of
transportation and the additiorial costs of transportation and usage
of an off-site incinerator did not make this alternative the best
overall.
4.
A PRP questioned how an incin~rator could be operated without proper
characterization of the wastes.
EPA/DNREC have required in the selected alternative that waste be
further characterized and treatability studies be completed in order
to determine the proper type of incinerator to be mobilized in order
to meet performance standards required by RCRA, and Air Pollution
Control Regulations.
Costs of Treatment and Recovery Wells
1.
New Castle County requested more detailed documentation of
implementation of 5 Recovery Well Systems and treatment of
groundwater.
Alternative 1 - 5 Recovery well system
Implementation Capital Costs -
$
322,130
o & M 10 years -
759.613
$1,081,743
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Subject:
Alternative 2 -
Costs from Alt. 1
$1,081,743
Capital Costs Treatment System
1,096,818
for 5 recovery wells
o & M for 10 years
2.574.888
$4,753,450
Remedial Action for Inert. Ridge and Grantham South Areas
1.
The PRP group stated that based on the technical information it
does not appear that any special remedial action is required for
the Inert Disposal, Grantham South or Ridge Area.
DNREC/EPA has documented direct contact risk to surface soils in
the Ridge Area, warranting remedial action.
In section 121 of SARA all remedies must be consistence with any
applicable relevant or appropriate requirements.
A no action at
the inert area would not meet the applicable closure require-
ments of the Delaware Solid Waste Regulations.
The
selected alternative, surface debris removal and capping is
consistent with the Delaware Solid Waste Regulations.
Also a no action at the Grantham South Area would not be
consistent with closure requirements under RCRA.
Capping this
area, the selected alternative, would attain this relevant and
appropriate ARAR.
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Subject:
Subject:
Evacuation of Wastes
1.
New Castle County expressed concerns about openning and
subsequent disturbance of the Drum Disposal and Ridge Areas.
They feel this action could result in significantly greater
concentrations of contaminants in the recovery wells which may
negatively impact upon the design and operation of the treatment
system.
DNREC/EPA recognizes that disturbance of the waste in the Drum
Disposal Area may increase the groundwater contaminant
concentrations for a short period of time during and immediately
after excavation.
This potential scenerio will be investigated
in the remedial design phase and handled in such a manner was as
to minimize impact to the treatment facility.
2.
A PRP stated the risk associated with excavating the wastes and
exposing them to ambient air had not been quantified.
DNREC/EPA
recognize a short-term risk to on-site workers from the
excavation of the Drum Disposal Area.
However DNREC/EPA
believes this short-term risk could be properly mitigated
through proper health and safety programs and site access
restrictions.
Pumoini and CaDDini
1.
A PRP suggested the alternative for pumping and capping the Drum
Disposal Area would provide a reduction in the mobility of
contaminants present in this area.
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Subject:
Subject:
DNREC/EPA agrees that capping the Drum Disposal Area would to
some extent reduce the mobility of the contaminants in this
area; however the potential source would still exist.
SARA
mandates reduction of mobility, toxicity, and volume if at all
possible, by using source treatment alternatives.
By removing
and incinerating these wastes, we will be reducing the ,mobility,
toxicity and volume of the major source of groundwater
contamination on site.
Extent and Nature of Contamination
1.
The PRP group feels the nature and extent of contamination at
the site still remains undefined.
DNREC/EPA has investigated, the air, surface soils, formation
soils, groundwater and surface waters on or near the site and
has adequately defined the nature and extent of contamination.
See Chapter 5 Nature and Extent of Contamination pg. 106-217
Remedial Investigation for Delaware Sand & Gravel.
In-Situ Technologies
1.
The PRP group suggested in-situ technologies should be examined
in greater detail for the Drum Disposal Area.
Several types of in-situ treatments were considered in the
initial screening (Delaware Sand & Gravel Feasibility Study.
Table 2.7)
The waste to be treated at Delaware Sand & Gravel
varies in contaminant content consequently many of these
technologies were eliminated since they are very contaminant
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Subject:
NC."'Jw
NCS007
-,.-
specific.
Bioreclamation of residual contaminated soil wAs the
only in-situ treatment reaching the final screening.
However,
Bioreclamation of soils was determined to exceed the cleanup
standards necessary for protection of public health and the
.>
environment.
Groundwater Treatment
1.
The PRP group noted that no type of treatment facility was
chosen for the groundwater discharge.
The actual type of treatment required to meet the applicable
NPDES requirements will be documented in the second operable
unit Record of Decision for Army Creek Landfill.
The facility
designated under the Army Creek Landfill Record of Decision will
treat all discharges.
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