United States
Environments! Protection
Agency
Office of
Emergency and
Remedial Response
EPA/ROD/R06-84/001
June 1984
Superfund
Record of Decision:
Bio-Ecology Systems Site,
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO. 12. 3. RECIPIENT'S ACCESSION NO.
EPA/ROD/R06-84/00l
... TITLE AND SUBTITLE 5. REPORT DATE
SUPERFUND RECORD OF DECISION: 06/06/84
Bio-Ecology Systems Si te, TX 6. PERFORMING ORGANIZATION CODE
7. AUTHORIS) 8. PERFORMING ORGANIZATION REPORT NO.
. V. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT NO.
". CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS 13. TYPE OF REPORT AND PERIOD COVERED
U.S. Environmental Protection Agency 'I";n",1 D()n
401 M Street, S.W. 14. SPONSORING AGENCY CODE
Washington, D.C. 20460
800/00
15. SUPPLEMENTARY NOTES
16. ABSTRACT
The Bio-Ecology site is an 11.2 acre tract located in Grand Prairie, Texas.
The site is bounded in all directions by private property and also on the east and
south by the tributaries of Old Mountain Creek. The Bio-Ecology waste disposal site
was a Class I industrial solid waste management facility which was permitted to:
(1) incinerate combustible liquids, slurries and sludges; (2) chemically treat acids,
caustics and other waste chemical solutions, excluding those containing heavy metals;
(3) treat waste waters using biological oxidation; and (4) landfill solids from other
treatment processes. The site was actively operated from June 1972 through 1978.
The cost-effective remedial alternative includes: raising the elevation above
the 100-year flood plain; construction of an on-site disposal cell with synthetic
liner and a leachate collection system; construction of a final cover, liner and
leachate collection and removal system in accordance with RCRA Part 264; stabilize
the waste and encapsulate in an on-site cell; construct a fence; and install a
grOUnd water monitoring system in accordance with RCRA Part 264. The capital cost
for the selected alternative is estimated to be $2,709,600. Operation and maintenance
costs for the first year are estimated to be $20,000.
Key Words: On-Site Containment; RCRA Landfill; Ground Water Contamination;
Ground Water Monitoring, RCRA Part 264
17. KEY WORDS AND DOCUMENT ANALYSIS
a. DESCRIPTORS b.IDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
Record of Decision
Bio-Ecology Systems Site, TX
contaminated media: gw, sw, soil, sludge
Key contaminants: solvents, PCBs, TCE,
metals
18. DISTRIBUTION STATEMENT 19. SECURITY CLASS (Tllis Report) 21. NO. OF PAGES
None 1R
20. SECURITY CLASS (Tllis page) 22. PRICE
None
EPA Form 2220-1 (Au. "-77)
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1.
INSTRUCTIONS
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2.
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LEAVE BLANK
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Reserved for use by each report recipient.
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TITLE AND SUBTITLE
Title should indicate dearly and brieny the subject ~'overa~e uf the report, and be disl'lay~'d rromin~'nlly, S~'I sllt'litk. if 1I~'tI, in ~malkr
type or otherwise subordinate it to main title, When a report is rrepared in morL' than Lln~' VOIUIIIC, n'",'at th~' rrilllary liliL', .Hld vol\lm~'
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REPORT DATE
Each report shan carry. date indicating at least month and yeu, Indkate the h;lsis un whkh il \\as ",'le~'tL'd (.',[1:.. .loll' oj'i~n,." .101.' oj'
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Ii.
e.
PERFORMING ORGANIZATION CODE
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7.
AUTHORISI
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zation.
8.
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Give name, street, city, state, and ZIP code. List no more than two levels of an ur~anila'iunal hireardlY,
10. PROGRAM ELEMENT NUMBER
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11. CONTRACT/GRANT NUMBER
Insert contract or grant number under which report was prepared.
12. SPONSORING AGENCY NAME AND ADDRESS
Include ZIP code.
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Indicate interim fina!, etc., and if applicable, dates covered.
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15. SUPPLEMENTARY NOTES
Enter information not included elsewhere but useful, such as:
To be published in, Supersedes, Supplements, etc.
18. ABSTRACT
Include a brief (200 words or less) factual summary of the most sil(nitkllnt information ~'untainl'd III 1111' 1I'l'ml. If 1111' 1\'l'lIfll.'''II;OI/lS a
significant bibliography or literature survey, mention it herc,
Prepared ill cuoperation with. Troll1slalllll1l1", I'rCSl'lIlI'd ;01 l'IIU 11'1 1'111 I' IIf,
17. KEY WORDS AND DOCUMENT ANALYSIS
(a) DESCRIPTORS. Select from the Thesaurus of Engineerir.~ and Sdl.'nlifi~' Tcrms thc pruper aUlh..rill'd II'rllls IIIal Idcnllfy Ihe majm
concept of the research and are sufficiently specific and precise to be used as iOlk~ I.'ntries for I.:ataluj:lnj:,
(b) IDENTlrJERS AND OPEN.ENDED TERMS - Use identifiers for project namlS, code namcs, eljuipment Ikslj:niltors, dc, Use "I'CII-
ended terms wrillen in descriptor form for those subjects for which no descriptor exists.
(c) COSA TI HELD GROUP. Held and group assignments are to be takl.'n from the 1965 COS,\ 11 Suhic...t Call'j:llry Ust, S!nI.:L' thc mil-
jority of documents are multidisciplinary in nature, the Primary Held/Group ils.signmcnus, will be Spt".III'. d"...pllnc, ar~'iI u' hU1!liI~
endeavor, or type of physical object. The application(s) will be crosNcfercneed with ,cl'undary I Il'hl/< .rulll' iI"Ij:IIIIICII!\ that wllllullll'"
the primary postingcs).
18. DISTRIBUTION STATEMENT
Denote releasability to the public or limitation for reasons other than security for cXilmplc "Rdeas~' 1;111111'111'11." ('il" all!, aVililahilil~' III
the public, with address and price.
18..20. SECURITY CLASSIFICATION
DO NOT submit classified reports to the National Technical Information scrvil:e,
21. NUMBER OF PAGES
Insert the total number of pages, including this one and unnumbered pages, but cxdudc distribution lis', II ilny,
22. PRICE
Insert the price set by the National fechnicallnformation Sl.:rvil.:c or the Government Printing Office, if known,
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ROD ISSUES ABSTRACT
Site:
............
Bio-Ecology Systems Site, Texas
Region:
VI
AA, OSWER
Briefing Date:
February 6, 1984
SITE DESCRIPTION
The Bio-Ecology site is an 11.2 acre tract located in Grand
Prairie, Texas. The site is bounded in all directions by private prop-
erty and also on the east and south by the tributaries of Old Mountain
Creek. The Bio-Ecology waste disposal site was a Class I industrial
solid waste management facility which was permitted to: 1) incinerate
combustible liquids, slurries and sludges~ 2) chemically treat acids,
caustics and other waste chemical solutions, excluding those containing~ .
heavy metals~ 3) treat waste waters using biological oxidation~ and.
4) landfill solids from other treatment processes. The site was ac-
tively operated from June 1972 through 1978.
SELECTED ALTERNATIVE
The cost-effective remedial alternative includes: raising the ele-
vation above the 100-year flood plain; construction of an on-site dis-
posal cell with synthetic liner and a leachate collection system; con-
struction of a final cover, liner and leachate collection and removal
system in accordance with RCRA Part 264; stabilize the waste and
encapsulate in an on-site cell~ construct a fence~ and install a ground
water monitoring system in accordance with RCRA Part 264. The capital
cost for the selected alternative is estimated to be $2,709,600.
Operation and maintenance costs for the first year are estimated to be
$20,000.
ISSUES AND RESOLUTIONS
KEY WORDS
1.
A source control remedy was considered which
provided a degree of protection somewhat
less than that of the fully protective RCRA
consistent remedy. However, the source con-
trol remedy which includes construction of an
on-site RCRA landfill was selected because it
complies with appropriate RCRA regulations
and provides a high degree of long ~erm reli-
ability with a minimal increase in cost.
. On-Site Containment
. RCRA Landfill
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Bio-Ecology Systems Site, Texas
February 6, 1984 .
Continued
ISSUES AND RESOLUTIONS
2.
A waiver was not granted from RCRA ground
water protection regulations (Part 264
Subpart F). Existing data was not adequate
to determine if contaminated ground water
was. leaving the site. A monitoring program
was developed to comply with RCRA. If con-
tamination is identified in the future, re-
medial action will be evaluated consistent
with the NCP.
-2-
KEY WORDS
. Ground Water
Contamination
. Ground Water
Monitoring
. RCRA Part 264
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RECORD OF DECISlOO
REMEDIAL ALTERNATIVE SELECTION
SITE:
Bio-Ecology Systems, Inc., Site, 4100 East Jefferson Avenue,
Grand Prairie, Texas
00CUMEN1'S RE.VI~
I have revie'Wed the following docl.1!Tlents describing the analysis of
cost-effectiveness of remedial alternatives for the Bio-Ecology Site:
- Bie-Ecology Site Investigation, W:>odward & Clyde Consultants,
April 1983.
~
.
-
~
- Bie-Ecology Remedial Alternatives Analysis, W::>odward & Clyde Consultants,
July 1983. .
- Staff summaries and recommendations.
Description of Selected Remedy
- Raise the elevation of the site above the 100-year flood plain.
- Construct an on-site disposal cell with synthetic liner and a
leachate collection system.
- Construct a final cover and liner and leachate collection and removal
system in accordance with standards promulgated under 40 CFR Part 264
, 'and applicable guidance.
- Stabilize the waste and place in on-site cell.
..
.
.
- Construct a fence with warning signs.
- Install a ground water nonitoring system in accordance with standards
promulgated under 40 ern Part 264.
DECI.ARATI~
..
Consistent with the Canprehensive Environmental Response, Chrrpensation,
and Liability Act of 1980 (CERCIA), and the National Contingency Plan (40 CFR
Part 300), I have determined that containment of wastes in an on-site landfill
in canpliance with applicable technical regulations of RCRA is a cost-effective
remedy and prcwides adequate protection of public health, welfare, and the '
environment. '!he State of Texas has been consulted and agrees with the approved
remedy .
I ha\7e also determined that the action being taken is appl.op£ iate when
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t
.
-
0-
.
.
",
- 2 -
I am also approving a ground water ~nitoring program to determine the
existence of any present ground water contamination outside the containment
area: however the decision to proceed with this cleanup does not enconpass
renec'iial action with respect to any ground water contamination that may be
discovered. If such ground water contamination is found, appropriat~ remedial
response will be evaluated, and I will make a future determination regarding
the compliance of this response with RCRA requirements. If no existing
contanination is found, the nonitoring program will ensure the continued
. effectiveness of the selected containment remedy. In accordance with section
104(c)(3), the State is r€quired to ensure the continued operation and
maintenance of the selected remedy.
~. ~ ~\;~--<~
lee M. 'Ihanas
Assistant Administrator
Office of Solid Waste and Emergenc:y Respcanse
~..
6" \~ ~ '-I
Dab
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Remedial Implementation Alternative Selection
Bio-EOOlogy Systems, Inc., Site
Grand Prairie, Texas
September, 1983
..
-
Site Location and Description
The Bio-Ecology site is an 11.2 acre tract located at 4100 East Jefferson
Avenue in Grand Prairie, Texas shown in Figure 1. The actual waste disposal
facili ty occupied a portion of the 11.2 acres owned by Bio-Ecology. The
site is bounded in all directions by ~rivate property and also on the east
and south by the tributaries of old Mountain Creek. Mountain Creek Lake
and the Trinity River are located approximately 0.75 miles southwest and
2.5 miles north of the site, respectively. The site is located in the
floodplain of Mountain Creek (Trinity River Basin) and has been extensively
flCX>ded on at least two past occasions during operations (June 1973 and.
June 1974). A site diagram of the Bio-Eoology Facility is shown in Figures -
2 and 3.
.
Site History
The Bio-Eoology waste disposal site was a Class I industrial solid
waste management facility, originally authorized by a permit issued by the
Texas Water Quality Board on April 24, 1972. Permitted activities included:
(1) incineration of combustible liquids, slurries, and sludges (subject to
'Iexas Air Control Board standards for odors and emissions): (2) chemical
treatment of acids, caustics, and other waste chemical solutions, including
those containing heavy metals; (3) biological oxidation of waste waters
resulting fran separation of ltUJd-water and oil-water mixtures and fran
chemical treatment of other wastes: and (4) a modified landfill of solids
resulting fran the other treatment processes. '!he site was actively operated
fran June 1972 through June 1978.
i
Operations at the site were characterized by frequent litigation
filed by the Texas Department of Water Resources and its predecessor agency
(Texas Water Quality Board) . Both agencies had attempted to force the -
company to comply with permit standards and all the applicable Federal and i
State laws and regulations. During the 6-year operation of the facility,
Bio-Ecology was cited for a nl.mlber of major violations including: ( 1)
construction of new facilities (i.e. - retaining basins) without proper
autoorization, (2) discharge of wastewater into Mountain Creek, (3) allowing
liquid levels in holding basins to reach the brink without any freeboard,
(4) storage of drums, several times beyond the permit maxi.nu..rn (200 drums),
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-2-
Fram June 3 through June 4, 1973, approximately 5 inches of rain fell
on the site during a 24-hour period. Approxirrately 90 percent of the
Bio-Ecology facility (11.2 acres) was inundated. State inspections of the
site otserved flooding in several storage basins and wastewater runoff into
Mountain Creek. The site was to have been designed to adequately protect
against a 24-hour, 25-year rainfall; however, the rainfall during June 3
through June 4 was of less than a 25-year frequency. Judgments were entered
by the Texas courts on July 6, 1973, and March 24, 1977, requiring Bio-
Ecology to comply with its permit and remedy the above mentioned violations.
On June 13, 1978, Bio-Ecology filed for bankruptcy under the provisions of
Chapter XI of the Bankruptcy Act.
..
-
After payment of all priority creditors, the Texas Department of Water
Resources was able to recover $28,870.50 trorn Bio-Ecology for cleanup
activities. In December 197~, a contract was made to partially close the
site. Under the contract, (1) all open receiving basins and pits were
drained, (2) all containerized wastes were bJried onsite and covered with ~
a pelletized lime blanket, and (3) sludges in various lagoons and landfills
were rroved to consolidate than onsite. Due to constraints in funding, a
number of metal tanks containing oils, solvents, and paint sludges remained
at the site. Approxirrately $34,000 (including $28,87U.50 obtained fram
Bio-Ecology bankruptcy) was expended during the period fram December 12,
1979, through February 15, 1980, for the partial site cleanup.
.
t
In November 1981, the application for a Cooperative Agreement for
remedial investigations and feasibility studies at the Bio-Ecology site
was filed. The Cooperat i ve Agreement between EPA and the State of TeXCIs
was approved on April 12, 19~2. An award of $328,000 was authorized to
conduct a remedial investigation and feasibility study (RI/FS) at the
Bio-Eco1ogy site. In November 1982, ~~ard-Clyde Consultants of Houston,
Texas, was selected to conduct the RI/FS. The site work for the investigation
was completed in January of 1983 and the final report was approved in
April of 1983. The Feasibility Study was started in F~bruary of 1983 and
was canp1eted in July of 1983. Tt'te major findings of the investigation
and feasibility reports are discussed in the section titled "Current Site
Status".
In addition to the above work an Initial Remedial Measure (IRM) has i
been performed at the Bio-Ecology site in September of 1983, to perform the
rem::>val of all surface structures at the site. The IRM cleal'U.lp activities
included the following:
1. Renove and dispose of approximately 80,000 gallons of hazardous
liquids and sludges. (organics, PCB's, Heavy Metals)
2. Decontaminate and rem::>ve the 15 storage tari
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4.
Surface cleanup. (miscellaneous debris, site grading, etc.)
This action was deemed necessary according to the National Contingency
Plan (NCP) section 300.68 with regard to hazardous substances in drums,
barrels, tanks, or other bulk storage containers above surface posing a
threat to public health or the environment and contaminated soi~s largely
at or near the surface posing a threat to public health or the environment.
CURRENT SITE STATUS
The Bio-Eco1ogy remedial investigation that was performed included a
hydrologic analysis, a stratigraphy analysis, a hydrogeological analysis
and a geochanica1 analysis. The following is a surrrnary on the results of
this investigation.
The hydrologic analysis showed the site to be poorly drained and sub-
ject to surface run-off, erosion and flooding. Approximately 75 percent
of the site is within the 10o-year floodplain.
.
.
t
The stratigraphic analysis identified four subsurface strata within
the upper nO feet at the site. The uppermost stratum fran the surface to
about 20 feet in depth consists of modern alluvial deposits fram the meander
deposition of Old Mountain Creek on the north, east and south of the site.
These m:>dern alluvial deposits are pervious deposits capable of transmit-
ting water vertically and laterally and are thus subject to infiltration
by rainfall and high flood waters of Old Mountain Creek. Underlying the
modern alluvial deposits are older alluvial deposits fran floodbasin deposi-
tion of the Mountain Creek valley. These deposits are primarily high
plasticity clays with occasional beds of low plasticity clays. The older
floodbasin soils contain fissures and cracks caused by cyclic shrinkage
and swelling. The older alluvial deposits therefore act as a leaky aquitard
capable of transmitting fluids vertically. These deposits vary in thickness
fran 25 to about 40 feet across the site. Below this stratum is about a
S-ft layer of remnant quaternary gravel deposits which is the first signif-
icant aquifer encountered. Beneath the gravel deposits is about a 20o-ft
section of the Eagle Ford shale. This shale is for all practical purposes
impervious and overlies the WOodbine aquifer. The WOodbine Aquifer is
used as a drinking water supply for the City of Grand Prairie (See Figure.
4 for a typical cross section). i
The groond water flow, at the time of investigation, was generally
fran northwest to southeast across the site in the remnant gravel aquifer.
Ground water encountered was also under an artesian head of about 15 feet
(measured from the older alluvial deposits). This aquifer is slightly
contaminated in the vicinity of the site and is subject to contamination
from wastes at the site migrating through the secondary structure of older
alluvial deposits. Ground water is present in the upper alluvial deposits
at water levels belOIoI the level of surface water in the adjacent stream.
channel and nearby pond northwest of the site. These surface waters are
recharging the alluvium at the site.
.
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The geochemical analysis showed:that surface contamination at the
site is primarily restricted to on-site locations and to off-site drainage
areas. en-site surface contamination is extensive for metals, cyanide and
organics. Composite samples fram the site indicate high concentrations of
lead (1,100 mg!kg), arsenic (210 mg!kg), and cyanide (1,030 mg!kg). Analysis
also indicated the presence of many organic contaminants including toluene
(19,000 ppb), trichloroethylene (1,000,000 ppb), benzene (1,500 ppb),
methylene chloride (87 ppb), and naphthalene (240,000 ppb). Off-site
contamination did not appear to be severe at the time of the field
investigation. Likewise, subsurtace contamination appears to be primarily
restricted to waste deposits and their vicinity.
There are approximately 40,000 cubic yards of wastes and highly
contaminated soils at the site.
The conclusions of the remedial investigation are the following:
o
.
...
-
0
Significant waste quantities containing high concentrations of
metals, cyanides and aromatic organics are present at the Bio-EcOlogy
site;
.
Seventy-five percent of the site is located within the 10o-year
floodplain and is susceptible to severe flooding;
o Migration pathways and migration mechanisms are present at the site
for potential significant long-term waste migration to surface and
subsurface waters and adjacent areas;
o
Evidence of surface contamination in off-site drainage ditches and
traces of subsurface contanination in the quaternary gravel aquifer
beneath the site were found;
o Waste migration to date has been primarily restricted to on-site
locations with the exception of past surface off-site migration
caused by flooding;
..
).
o Target receptors currently impacted are adjacent land areas (dead
and dying vegetation) and surface waters;
-
i
Remedial actions should be undertaken to prevent future surface and
subsurface migration of wastes to surface water, groond waters and
adjacent prope.rty; and
o A search of drinking water well records was conducted during the
investigation and did not reveal anyone using the shallow aquifer.
-------
.
-5-
The feasibility study completed by Wbodward &
July 1983 developed the following objectives based
remedial investigation:
Clyde Consultants in
on the results of the
o
Remove above ground structures, dispose of contents, ana treat the
associated northern off-site contaminated soil area;
o
Raise site above IOo-year floodplain;
o
Provide anequate site drainage;
o
Treat special wastes (PCBs in Tank T2: buried drums and containers
including medical vials and laboratory chemicals; areas of high
arsenic concentrations: and areas of cyanides): and
o
Control off-site migration of wastes by surface and subsurface.
migration pathways to surface and subsurface waters and adjacent
land areas in order to mitigate future impacts on these target
receptors. (No significant air migration problems were detected
during the site investigation.)
.
..
-
The feasibility study developed nine alternatives based on these
objectives. A no-action alternative was also considered for the Bio-Ecolcx.JY
site, but was eliminated prior to initial screening based on its inadequacy
for meeting response objectives to mitigate the site-specific problems and
the fact that pathways exist for significant potential migration of surface
and subsurface contamination.
t
The nine alternatives were screened for performance, cost and
environmental factors. The Feasibility Study includes a detailed screening
,procedure and the results are s\..ll'!l'narized here. Three alternatives were
rejected based upon performance and the low reliability of adequately
controlling the source of contamination. One alternative (off-site transport
and disposal) was rejected based on cost since its cost was about three
times more than the next most costly alternative and did not provide
substantially greater public health or environmental benefit.
-------
.
-6-
The remaining five alternatives were developed and fully evaluated.
More accurate cost estimates were prepared for each. They are:
Alternative
Estimated Cbsts
Design Cbnstruction
4 - Stabilize wastes in-place and install
slurry trench through modern alluvium
(3D-ft)
$136,300
$1,604,200
5 - Stabilize and consolidate waste
and install slurry trench
through modern alluvium (30-ft)
156,700 1,844,800
178,800 2,104,000 .
177,200 2,085,200
.
6 - Stabilize wastes in-place and install
slurry trench through quaternarj sandi
gravel layer (60-ft.)
..
-
7 - Stabilize and consolidate wastes in
clay lined cell (with leachate collection
system )
8 - Stabilize and consolidate wastes in
synthetic/clay lined cell (w/leadhate
collection system) (RCRA approved facility)
212,000
2,497,400
All the above alternatives include a clay cap, a ground water nonitoring
system, and raisi~ the site elevation above the 10D-year floodplain. The
costs noted above include capital costs. In addition to the costs nentioned
above, post closure m:mitoring costs are estimated to be about $20,000 the
first year and then about $7,000 per year for 30 years arid O&M costs for
each alterntive are estimated to be $1000 to $2000 per year for 30 years.
~
It
A cost-effectiveness evaluation was performed by professional engineers
on the W::xxIward Clyde staff on the above alternatives. This evaluation
process used a weighted rating system to quantitatively rank the effectiveness
of the alternatives. Four categories are listed below along with the i
available number of points for each:
Category
Available Points
(1)
(2)
(3)
(4)
Human Health !mpacts
Feasibility and Performance
Environmental ~cts
Tine liness
30
30
10
5
-------
-7-
The following is an explanation of the elements considered in each of
the five evaluation categories:
(1) Human Health Impacts (30 points): ]mpacts on human health were
judged on anticipated impacts of each alternative on air, soil~nd water in
the region, that could potenti~lly affect the health .of humans. Human
contact with affected ground water, run-off and run-on water, air in the
site area, and site soils were considered during both the remedial activities
and after cleanup of the site. one-half of the category weight was a110ted
for impacts during construction, and one-half for after construction.
Alternatives anticipated to have small adverse effects on human health
received high points. Alternatives anticipated to have large adverse
effects on human health received low points.
..
-
(2) Feasib1ity and Perfamance (30 points): Feasibility of each
alternative was judged based on the applicability and degree of sophistication
of the alternative. Performance of each alternative was rated on its.
potential to accomplish four main objectives: (1) raise site above 10o-yp~r
floodplain, (2) provide adequate site drainage, (3) treat special wastes,
and (4) control off-site migration of contaminants. Alternatives judged
to be the most feasible and most effective in accomplishing the objectives
were given the most points. Alternatives judged to be less feasible and
effective were given lower points.
.
t
(3) Environmental Dnpacts (10 points): Each alternative was evalu-
ated using two main criteria: (1) impacts during construction (short
term) and (2) ~cts under normal conditions (long term). These evalua-
tion criteria include environmental impacts on air, water and soil. Factors
specific to the site considered were: degree of contaminant hazard, avail-
ability of pathways for contaminant movement, and sensitivity of potential
receptors. '!tie above itans were considered in judging each alternative's
.. impact on air, water and soil. Although environmental impacts are allocated
only 10 points in the evaluation, performance (30 points) and human health
impacts (30 points) are directly related to alternative effectiveness in
mitigating site specific environmental problems. The evaluation of environ-.
mental impacts was therefore limited to the inrnediate (direct) and long
tem impact of implementing the alternative. High points were given to
alternati ves that were judged to have low environmental impacts and low ~
points were given to alternatives judged to have high environmental ~act'.
(4) Timeliness (potential for phasing). (5 points): Each alternative
was reviewed to determine which activities may be conducted independently
and which activities must be conducted concurrently. Alternatives which
were judged to have the greatest flexibility (activities which may be
conducted independently) were awarded high points. Alternatives whose
-------
-8-
The effectiveness of each alternative was evaluated on a basis of
750 possible total points, and judged in each of the four categories on
an absolute scale fram 1 to 10 (10 considered excellent, 1 considered
poor). Environmental Impacts were di~ided into two groups --- s~rt te~
and long term. Impacts during construction (short tenn) were allotted 30%
and impacts after construction (long tenn) were allotted 70% of the environmental
impact category rating. The 1 to 10 ratings for each category were multiplied
by the respective total possible points for each category to obtain a
total weighted average evaluation score tor each alternative.
The cost of installing or ~lernenting each alternative was estimated
to be compared against their effectiveness. A list of individual cost
items estbnated tor each alternative is presented below:
..
-
o ~~gineering Design 0 Site Cleanup
0 Mobilization 0 security .
o Insurance and Bonds 0 Land Lease
0 Temporary Installations 0 Reporting
0 Transportation 0 Disposal
0 Water Treatment 0 Equipment Cleanup
0 Contaminant Treatment 0 O&M Costs
.
The following table illustrates the results of the evaluation:
EVAIlJATIOO RESULTS
MAXIMUM
E.VAIlJATlOO CATffiORY POSSIBLE
smRE
Alternative lb.
4
5
6
7
8
EFFECTIVENESS FACTORS
Hunan Health 300
~ Impacts
"
.
Feasibili ty and 300
Performance
Environnental 100
Impacts
Timeliness 50
Effectiveness Scores 750
(X)ST
Cost EstDnate ($k)
200 185 235 192.5 240
175 192.5 237.5 230 250 -
i
63.5 70.7 76 71.3 76
35 36.7 37.5 20 18.3
474 485 588 514 584
$1,604.2
1,844.8 2,104
-------
-9-
Based on this evaluation, alternatives 6 and 8 are more effective than
the other alternatives, but roughly comparable to each other. Alternative 8
is slightly more protective of human health and is also expected to perform
better over an extended period of time. Alternative 6 can be implemented
sooner and it costs less. Overall, Alternative 8 is more effective than
Alternative 6 in that it provides the highest level of public health protection
and the best long-term reliability.
Community Relations
.
-
Documents made available for public comment included the Remedial
Investigation and Feasibility Study reports, two addenda to the Feasibility
report, the draft Record of Decision (ROD), and a copy of tne press release
announcing the cc:mrtent period. The public cament period for the selected
alternative was held December 2 through December 23, 1983. A press release
was issued announcing this on November 23, 1983. A public meeting was held.
at the Grand prairie Canm.mity Center on DecE:!mber 15, 1983. Two represen- .
tatives fran 'IDWR and two fran EPA were present. William B. Hathaway
(EPA, Region VI) gav~ a general presentation on Superfund and the key
alternatives and Charles Faulds (~~) presented the technical data fram
the study. Carments received at the rreeting were all favorable, expressing
confidence in and than~s to EPA for their tiIrely response to the problem
at the Bie-Ecology site. written c:arrcents were received by three of the
potential responsible parties. Responses to these comments are in the
Responsiveness Surrmary attached.
.
Recommended Alternative
p.
..
.
Section 300.68 (j) of the NCP states that "The appropriate extent of
rerredy shall be determdned by the lead agency's selection of the rerredial
alternative which the agency determines is cost-effective (i.e. the lowest
cOst alternative that is technologically feasible and reliable and which
effectively mitigates and mdn~izes damage to and provides adequate protection
of public health, welfare, or the environnent). II It is EPA policy to consider
the degree to which a rerredy under CERCIA is consistent with other envirormental
laws and regulations in determdning whether that remedy provides fully
adequate protection to human health, welfare, and the envi~nment.
,
Alternative 8 complies with RCRA requirements for a hazardous waste
landfill and also would include ground water monitoring to determdne if
. there is contamination that has already migrated fran the site. If ground
water contamination is detected beyond the waste managerrent boundaries of
the landfill, RCRA would also require implementation of a corrective action
program. The lined landfill with a leachate collection and cap system would
have a high degree of reliability for containing the wastes placed in the
landt ill.
The feasibility study also evaluated another source control remedy
(Alternat i ve 6) whi ch provided a degree of protection sanewhat less than
that of the fully protective,IRCRA consistent renedy bJt at slightly less
-------
-10-
Alternative 6 includes the installation of a 60-foot slurry trench around
the per~eter of the site, raising the site above the 100-year flood plain,
stabilizing the wastes, construction of a clay cap, and construction of a
fence. '!tie cap and slurry wall, keyed into an ~permeable stratum, are
expected to be effective for an extended period in preventing miqration of
wastes beyond the site boundary. In addition, the slurry wall is susceptible
to leakage over time due to possible long-term increase in permeability. In
contrast, synthetic liner systems, combined with leachate collection, are
expected to be effective indefinitely given the nature of the wastes present
at the Bio-Ecology site. tong-term ground water monitoring outside of the
containment cell should be sufficient to detect any leakage. If necessary,
implementation of a corrective measure addressing the leakage would be
performed.
.
-
The remainder of the alternatives evaluated were clearly not as effective
or reliable as either Alternatives 8 or 6. Alternatives 4 and 5, although
less costly, are not as reliable as Alternative 6. '!tIese alternatives proPife
a shallow slurry trench constructed into the alluvial system. '!tie alluvial-
deposits are not a good tie-in stratum for a slurry wall because of the
presence of secondary structures of slicken sides and fissures. '!his would
allow ground water to flow into and through the containment area. Therefore,
alternatives 4 and 5 pose a higher risk for waste migration. Alternative 7,
although less costly than alternative 8, is less reliable due to long-term
increases in permeability similar to the problems described for Alternative 6.
.
The potentially responsible parties also proposed a remedy which would
cap the site but did not include waste stabilization or fixation. Their
plan does not propose either a deep slurry wall or a synthetic liner system.
'!tIis remedy has poor reliability and does not adequately contain the wastes.
t
Alternatives 4, 5, 6 and 7 do not comply with RCRA technical requirements.
Hazardous wastes in each alternative are removed, stabilized and/or fixed and
placed into new or expanded trenches. These alternatives do not cortply with
Part 264.251(a) and 264.301(a) of RCRA technical requirements (design and
operating requirements for waste piles and landfills). '!tie alternative
proposed by the potential responsible parties is not consistent with these
RCRA technical regulations.
Base:3 on this analysis, Alternative 8 is the least cost option that
adequately protects public health, welfare, and the environment and is
consistent with other envirorunental acts. 'lherefore, Alternative 8 is the
recanmended cost-effective remedy. Details of the recarmended alternative
are shown in Figures 6 and 7. The recarmended remedy inclooes ground water
mnitoring. If existing ground water contamination is found beyond the
boundaries of the containment cell, EPA will make a separate evaluation to
determine whether a corrective action program is consistent with the NCP.
Presently, available infonnation is insufficient to determine the need for,
and cost of, such a program.
-------
-11-
Since the site is located in the lOo-year floodplain, the requirements
of Executive Order No. 11988 covering Floodplain Management were reviewed.
A Floodplain Management Assessment was prepared (Addendum 1) for the propcsed
remedy. This assessment concludes that the proposed remedy will not
create a substantial risk to public health or the environment due to a
IOo-year flood if certain measures are followed. The responsible government
agencies will be contacted during the design stage to ensure that the
reccmrendations are iITp1emented.
Tentative Schedule
..
-
- Complete Enforcement Negotiations
- Sign ROD .
- Issue Administrative Order
- Cocperati ve Agreement Anendment
(to fund and to incorporate the design)
- Start Design
- Complete Design
- Start Cleanup
- Complete Cleanup
Januarj 1984
May 1984
May 1984
June 1984
July 1984 .
September 1984
February 1985
Septen6er 1985
..
p.
J.
-------
.oJ
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o
..
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..
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Figure 6
4"0
.30
.20
S,n'hetlc line' willi leochol. Collecllon
ISf!f! ',plcol uclion b.lo..)
41Q
I
~ ,J
OLDER
ALLUVIAL
DEPOSITS
,
"'0~
3110
----- -- --'- --- - -- -----~
---
1- - - - REMNANT QUATERNARY ALLUVIAL GRAVEL DEPOSITS
r- - -TYPICAL SECTION: SYNTHETIC LINER - - - - - - - - - - - - - - --?
WITH LEACHATE COLLECTION SYSTEM
IN T S I
. 0--. S.~60 ..;1 HOPE
. ~ ,.. ,.".,.,., PYC PI..
t . C_U". CI., '0' 0.. c...,...
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FORO GROUP
810- ECOLOGY
SITE
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Figure 7
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,
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LEGEND
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--
"'0'., " L ifte
F."ce (10 be "",ow.ell
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AlHANATIVE ,,- PLAN VIEW
~oo
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----
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810 - ECOLOGY
-------
.Table 1
COST SUMMARY - ALTERNATIVE 8
STABILIZE AND CONSOLIDATE WASTES IN SYNTHETIC/CLAY LINED CELL AND CAP
-
1983 Design 1984 Construe; ',n
Component Cost ($) Cost ($) *
Design 212,200
Construction
1. Temporary Site Perimeter Dike/Ditch 64,000
2. Excavation of Special Wastes 3,508.
. 3. Treatment of Special Wastes 16,000
.
- 4. Backfill Special Wastes 3,100
5. Excavation of Sludge Wastes 109,400
6. Stabilization of Sludge Wastes ., .--- 390,100
7. Backfill of Sludge Wastes 123,200
B. Excavation of Contaminated Soil 17,800
9. Backfill of Contaminated Soil 23,000
10. Excavation of Lined Cell 71,800
: 11. Synthetic/Clay Liner (W!Leachate
Collection 367,900
12. Backfill of Non Contaminated Soil 89,700
13. Synthetic/Clay Cover/Cap 443,000
.. 107,100
J. 14. Temporary Storage Area Dike
i
Weather Contingency - 234,300
Contractor Overhead 206,400
Construction Management, Engineering
. Te8ting 227,100
'rotal Cos ts
$212,200
$2,497,400
*1983 Co8t 8dju8ted 7. for inflation
-------
...11
I'.
Table 2
IILTfJlJlJlTE NO. 8 - CONSTIIUC1' I 018 SCHEDULE
1I..~lJorbaUon Tp. In Itont.ha
0 I 2 J 4 '5 (, 7 A 9 10 11 12 1J 14 15
I I 1 I 1 1 I 1 1 I I 1 I 1
91", .... r ~ ~." :.!8' :~. and
PT-.r.:.!..-.":
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.'
-------
ADDENIXJM 1
Bio-Eco1ogy Systems, Inc., Site
Grand Prairie, Texas
Remedial Alternatives Analysis (1)
FLOOD PIAIN MANAGEMENT ASSESSMENT
I.
Purpose
The purpose of this addendum is to:
1.
Review Executive Order No. 11988, May 24, 1977, 42 F. R. 26951
entitled Floodplain Management.
2.
It
..
- 3.
4.
Review applicable statutes referred to in the Executive Order
as requ ired.
.
Review the Bio-Ecology Site Remedial Alternatives Analysis in
areas discussing flood plain management.
Summarize the review and describe additional technical requirements
to comply with applicable requirements.
II.
Introduction
The Site Investigation report (2) developed a hydrological description
and analysis of the Bio-Ecology site and is presented in part in this
addendum as follows:
..
J.
The Bio-Ecology site is located in the west Fork of the Trinity
River watershed. Specifically, the site is located at the mcoth
of the Ma.mtain Creek watershed, downstream of the Mountain Creek
Lake and Dam. A small tributary of Old Mountain Creek flows
along the north, east and southern boundaries of the site. Two
u.S. Geological Survey Gauging Stations No. 08050050 and 05050100
are located upstream and downstream of the site, respectively.
i
Station No. 08050100, Moontain Creek at Grand Prairie, Texas, has
been in operation since 1960. The U.S. Geological Survey maintains
the station which is located on the north side of Jefferson Boulevard
(State Highway 80). For the period of record noted above, the
maxim..un discharge recorded in Mountain Creek was 38,100 ft.3/sec
which occurred on April 19, 1976 (gauge height 24.21 ft). However,
the maxinum water level recorded at this site was 24.62 feet
-------
-2-
Drainage in Mountain Creek is affected by the volume of releases
made at the Moontain Creek Dam and the back water effects of the
West Fork of the Trinity River. Approximately 206 square miles
of watershed are drained upstream fran the site. The U.S. brmy
Corps of Engineers has estimated the following water surface
elevations at the Jefferson Boulevard crossing of the creek:
25-year frequency
50-year frequency
100-year frequency
Elevation 433.0
Elevation 434.5
Elevation 436.0
Based on these elevations, it is estimated the 100 year frequency
elevation in the vicinity of the site will be approximately 437.00
feet above rrean sea level. Using this elevation, approximately 75
percent of the site is located within the 10o-year flood plain
as shown in Figure 23.
.
..
-
The site is also located in a high hazard zone (as defined by the
U.s. Army Corps of Engineers) with respect to the Moontain Creek
Dam. In the event a failure were to occur in the dam, it is
likely that the flow velocity and discharges in the vicinity of
the site would be high. The Texas Department of Water Resources,
Dam Safety Group, has conducted a Phase I Dam Safety Analysis of
the structure. These data will be considered in developing remedial
plans for the site.
I'
P-
I.
On a local level, the Bio-Ecology site drains radially in all
directions (See 1 ft contours of Fig. 23). Fran Technical
Paper 40 "Rainfall Frequency Atlas of the United States", U.S.
Departrrent of Commerce, the 10o-year 24 hour rainfall in the
vicinity of the site is estimated to be 10.50 inches. Based
on the site topography, the surface runoff rate depending on
unit rainfall and type of cover will range fran 0.75 to 1.75
feet per second. This rate of runoff has been sufficient to
cause surface erosion and hence surface migration of contami-
nants during periods of intense rainfall. The surface migra-
tion of contamination has been tE!tp)rarily reduced by the
partial soil covering placed during the site closure operations
. in 1979.
i
III. Proposed Site Remedial Action
The prq>osed remedial action at the site involves the stabilization of
on-site wastes, treatrrent and stabilization of special wastes, and construc-
tion of a landfill with liner, leachate collection system, and clay cap.
The following proposed construction and treatrrent activities are anticipated
-------
-3-
1. A perimeter dike with a shallow interior drainage ditch will be
built around the site outside of the areas of known contamination. The
dike and ditch will contain, divert, and store surface water within the
site for treatment and/or disposal. All waste material stabili~tion and
remedial action activities will be performed within the diked area. The
top of the dike will be of sufficient elevation to hold IOo-year floodwaters
away from the \ltX)rk area.
The dike will be removed after the remedial action is completed.
2. The special wastes (cyanide and arsenic) which have been identified
on-site will be chemically treatec, neutralized, and disposed of (buriej)
in the on-site landfill.
3. The waste sludges will be excavated, stabilized, and replaced in
the on-site landfill.
.
..
.
-
4.
The entire site will be raised above the IOO-year flood plain.
5. A landfill with liner and leachate collection system will prevent
lateral ndgration of contaminants from the site through the ground water.
6. A clay cap will be placed over the landfill to ndnimize surface
infiltration. Fertilized topsoil will be placed over the cap and seeded
to provide a grass cover.
7. Post closure rronitoring of the site will be performed after the
remedial actions are completed.
r.J.
Flood Plain Regulatory Requirements
.
..
J.
In accordance with Executive Order 11988, Floodplain Management (3),
an applicable executive agency shall provide leadership and shall take
action to reduce the risk of flood loss, to ndnimize the inpact of floods
on human safety, health and welfare, and to restore and preserve the natural
and beneficial values served by flood plains. In addition, an agency has
the responsibility to evaluate the potential effects of any action that i
may be taken in a flood plain and to ensure that the design of the action
min~izes potential har.m to or within the flood plain.
As a part of the preparation of this addendlD1\, the follOrling agencies
have been identified as having flood plain management responsibilities:
u. S. Environmental Protection Agency
U. S. Arn¥ Corps of Engineers
Texas Departnent of Water Resoorees
City of Grand Prairie, Texas
-------
-4-
Specifically for Bio-Ecology site remedial actions, the proposed re-
medial action will be designed, constructed, operated, and maintained to
prevent the washout of a~ hazardous materials by a IOO-year flood.
-
The listed agencies will be provided with the design and construction
sequence of any remedial actions to ensure that the actions meet the above
requirement. The submitted design will include the construction of any
temporary facilities during the performance of the remedial action.
.
-
The EPA has determined that siting and construction of the remedial
action within the flood plain is the only praticable alternative consistent
with law. The only alternatives evaluated which would not require construc-
tion of a permanent cap on the site were the no-action alternative and
total excavation and rerroval of all contaminated soil and ground water.
The no-action alternative is inconsistent with the NCP because it fails to
address the threat of further migration of wastes fran this site~ ccrcplete ~
removal and off-site disposal of all contandnated material was not cost-
effective.
I'
v.
Flood Hazard Assessment
Two major flood hazards exist at the Bio-Ecology site.
These hazards
are:
1.. The IOo-year flood event
2.
The failure of the Mountain Creek Darn
The prq;>osed remedial action at the site involves the construction
of a temporary dike to prevent IOo-year floodwaters from entering the.
site. Floodwaters could potentially wash away hazardous materials from
the site while these materials are being treated and stabilized during the
remedial action.
..
;a.
The prq;>osed remedial action also includes raising the entire site
above the IOo-year flood plain to prevent the scouring of any materials
away from the site. Raising the site elevation will not have an adverse
impact on the surrounding environment during flooding because the area
being raised is small when compared to adjacent areas in the flood plain.
i
The design details of both the temporary dike and the inperneable cap
will include provisions to prevent the erosion of the sides of the tEltpOrary
dike and the site cap during floods less than or equal to the lOo-year
flood. Erosion protection alternatives include: (1) flexible protection
such as rock riprap or soil fabrics; (2) solid (rigid) protection such as
concrete retaining walls or gabionsi (3) and vegetation protection.
The hazard classification of the Mountain Creek Dam is considered high
because of the development and habitation on the Mcuntain Creek flood plain
downstream of the dam. Dams in the high hazard category are those located
where dam failure may cause the loss of six or m:>re hunan lives and exces-
sive econanic loss. H~ver, an inspection of the dam did not find any
-------
-5-
No ~diately hazardous conditions exist at the Mountain Creek Dam
and Reservoir. The darn is in good condition, and there are no seepage
areas of ponded water along the downstream toe. The downstream slcpes,
including the repaired slide area, are in good condition. The s2rinkler
system has resulted in a gcx:>d cover of grass on the downstream sicpe. The
spillway structure is sound and shows little or no sign of cracking or
settling. The gates and hoist mechanisms appeared to be in good condition.
In surrmary, the project is judged to be in good condition.
It is, therefore, reasonable to conclude that the proposed remedial
actions at the Bio-Ecology site will not exhibit a substantial risk to the
environment or human health due to flooding up to the IOO-year flood if
the following concerns are addressed:
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1. The design of the remedial action is sufficient to prevent erosion.
of the temporary dike and site cap during flooding. .
2. The Moontain Creek dam is operated and maintained to ensure that
hazardoos conditions at the dam and reservoir do not develop.
.
3. The raising of the site above the IOO-year flood plain does not
adversely iIrpact the current extent of the IOo-year zone.
These concerns will be addressed through the responsible agencies
(See Section IV) during the design phase of the remedial actions to ensure
the flood hazards are mitigated.
t
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ADDENrX.JM 2
Bio-Ecology Systems Site
Grand prairie, Texas
Remedial Alternatives Analysis (1)
BIo-ECOUX;Y GROUND WATER MONlTORIN:::; PRCX;:RAM
I.
Purpose
The purpose of this addendum is to:
1.
Review the Bio-Ecology Site Remedial Alternatives ~~alysis in
areas discussing a post closure ground water monitoring pl~~.
2.
Describe in more detail a post closure ground water plan.
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II.
Introduction
The Site Investigation report (2) presented a description ~~d analysis
of the Bio-Ecology site hydrogeology and is presented in part in this
addendum as follows:
The principal aquifers of Dallas County are sands of the Twin
Mountain FODmation, the Paluxy FODmation, and the WOodbine
Group. The Paluxy and Twin Mountain Formations are present
beneath the site at about an elevation of -600 feet and -1450
feet, respectively. The Vb:xibine is present at about eleva-
tion +180 feet, or about 250 feet below existing ground surface.
t
The Woodbine Group is the shallowest major aquifer beneath the
Bio-Ecology site. The WOodbine is a water table aquifer where
it crops out west of the site (Tarrant County and west Dallas
County), but beneath most of Dallas County it is artesian. The
pr~ source of recharge for the WOodbine is rainfall'on the
outcrop, with other sources consisting of surface water seepage
fran lakes. and streams. Sand development is limited in the
Wbodbine section in the site area; cor~equently, this section
would not be considered a major section of the aquifer in the
region.
i
'I?1e Eagle Ford Group overlie.s the Woodbine and is considered an
aquitard. The fact that the Wcxrlbine aquifer is artesian in the
area dertcnstrates this relationship. The Eagle Ford is canposed
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usually dense, rather impervious, and do not constitute consist-
ently porous water horizons. Early investigators characterized
the Eagle Ford as highly indurated, of laminated character, and
intermixed with selenite gypsum in minute lenticular crystals.
water flowing through this formation is generally bitter and dis-
agreeable to the taste.
III. Proposed Site Remedial Action
The proposed remedial action at the site involves the stabilization
of onsite wastes, treatment and stabilization of special wastes, and con-
struction of a deep slurry trench and clay cap around the stabilized and
contaminated areas of the site. 'ihe following proposed construction and
treatment activities are anticipated on the site:
1. A perimeter dike with a shallow interior drainage ditch will be
built around the site outside of the areas of known contamination. The
dike and ditch will contain, divert, and store surface water within the
site for treatment and/or disposal. All waste material stabilization and
renedial action activities will be performed within the diked area. '!he
top of the dike will be of sufficient elevation to hold 100-year floodwaters
away from the ~rk area. The dike will be rE!tDVed after the remedial
action is canpleted.
2. The special wastes (cyanide and arsenic) which have been identified
onsite will be chemically treated, neutralized, and disposed of (buried)
onsite.
3. '!he waste slooges will be excavated, stabilized, and replaced in
.the excavated areas of the site.
4. Wastes will be placed in an on-site disposal cell with synthetic
liner and a leachate collection system and capped in accordance with RCRA
regulations (40 CFR Part 264).
5. '!he entire site will be raised above the 100-year flood plain.
6. ~st closure ronitoring of the site will be performed after the
remedial actions are ~leted.
IV . Proposed Post aosure GrouOO Water M::Jni taring Plan
A ground water J1Dnitoring plan is intended to detect any migration of
CXX1taminated ground water fran the treated and stabilized wastes within
the oontainnent slurry trench. The proposed plan will inclooe the follow-
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1. Install gro.md water mmitoring wells of sufficient number and at
the apprc:priate lcx::atims and depths to yield gramd water samples fran
the quaternary aquifer. This plan includes six to eight wells "around the
disposal cell CO'Ii>leted in the quaternary aquifer. The exact locatims and
depths, including well screen lengths, will be deteDnined in the detailed
design of the plan.
2. A gra.md water sampling and analysis plan will be develcped to
incluqe the procedures and techniques for the follOriing activities:
a. Sa:t1ple collectiai.
b. Sample preservati01 and shipnent.
c. Analytical procedures including quality c01trol
d. Chain of custcxiy cmtrol.
procedures.
Prior to sampling a gro.md water mmitoring well, the grcund water
surface elevatim shwld be measured.
3. Grc:und water sampling and analyses will be cmducted quarterly
for the first year after the canpletim of the remedial actim to establish
backgra.md parameter cmcentratims in the gra.md water.
<
After the first year, gro.md water sampling and analysis will be
cmducted semi-annually to deteDnine whether there is a statistically
significant increase (Ner backgramd coocentratioos in the gro.md water.
If a statistically significant increase occurs ewer backgramd c01centra-
tiQ"lS, EPA and the Texas Department of Water Resc:urces will jointly evaluate
the release to deteDnine if additimal remedial actims are necessary. .
" 4. '!'he gramd water analyses shwld detemdne, at a minimLn, the
foHewing parameters:
AlSenic
aariln
Cadmi\lll
Chranium
Lead
MereuI}'
seleniln
Sil ver
Cyanide
Iii
Specific Cmductance
Total Organic CaIbm
Total. Organic HalOJen
In additiO'1 to the abole paIC!l'Oeters, 0'1e sauple fran a dcwngradient
well and O'1e sample fran an upgtadient well will be analyzed for priority
pollutants.
5. Gramd" water mcJ'1itorirg will ca1tinue for at least 30 yeatS after
the remedial actiO'1. After 30 years, the site will be reevaluated to
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REFERENCES
1.
Remedial Alternatives Analysis, Bio-Ecology Site, Grand Pr~~ie, Texas,
Texas Department of Water Resources, July 1983, Contract No. 14-300247.
2.
Site Investigation, Bio-Eco1ogy Site, Grand Prairie, Texas, Texas
Department of Water Resources, April 1983, Contract No. 14-30027.
3.
Executive Order 11988, 42 F.R. 26951, May 24, 1977 Floodplain Management.
4.
Phase 1 Inspection Report, National Dam Safety ?rogra~, Mountain Cree~
Darn, Dallas County, Texas, Inventory No. T.X00827, U. S. Corps of Engi-
neers and Texas Department of Water Resources, January 1978.
.
.
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ADDENIXJM 3
Bio-Ecology Responsiveness Summary
The following responsiveness summary contains responses to comments
received during the public ccmrent period. The feasibility study report
and draft Record of Decision made public at that time indicated a preference
for Alternative 6 (on-site containment with a cap and slurry wall). EPA
has determdned that Alternative 8 (on-site containment in a landfill with
liner and leachate collection system) should be implemented because it is
consistent with the applicable RCRA technical regulations and provides
greater long-term reliability and therefore results in a level of protection
of public health, welfare, and the environment considered adequate by EPA.
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Ccmrents
Response To
Thoopson & Knight Letter
on the Proposed Remedial Alternative
For the Bio-Ecology Site
Grand Prairie, Texas
Comment - The EPA proposal is not cost-effective and contains
technical deficiencies
Response
EPA's rationale for the selection of Alternative 8 is set forth in this
document in the section entitled "Rerredial Inplerrentation Alternative
Selection." The response to each canrrent concerning alleged technical
deficiency is detailed below.
The following staterrents respond to the 8 points mentioned on pages 2
and 3 of the Thoopson and Knight letter dated December 23, 1983. .
1.
The cost of obtaini~ permission frem various landowners to construct
a temporary off-site berm around the site was not included because
this cost is expected to be negligible. Pemission frem only two
adjacent landowners will be required. In previoos discussions with
these landowners, a willingness to cooperate was e~ressed on their
part. One landowner has specifically stated that temporary installations
on his pr~rty were acceptable. Both parties have expressed a desire
to "clean this mess up." It is therefore reasonable to assume that
little rrore than sinple administrative expenses will be incurred. It
should be noted that the feasibility report (p. 64) included
consideration of land lease costs. The emission of these ndnor
charges as a line item does not affect the validity of EPA's selection
of the appropriate remedial option.
The proposed stabilization method will not increase the possibility
of excessive leachate fran the site. Alternative 8 offers the
greatest degree of protection against leachate escaping from the
site; otherwise, only the "pick it up and haul it off" alternative
would significantly decrease the possibility of leachate escaping
frem the site.
2.
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3.
Damage to the proposed cap fran erosion, dessication, and root
penetration will be prevented or mitigated by a regular cperational
and maintenance (O&M) schedule.
4.
Stabilization activities will be conducted within a diked area such
that there will be no increased surface water release during the
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backhoe excavations conducted during the site investigation and air
monitoring during this same tUne did not reveal any air release Unpact
beyond the llnmediate excavation area inside the site fence. Health
threats to enployees engaged in ranedial action are minirniz~_through
the extensive safety requirements mandated by EPA. All employees
engaged in ranedial action do so only under controlled conditions.
This one-time risk under monitored and controlled conditions is
proposed in order to alleviate the long-ter.m risk to the public of an
uncontrolled site.
5.
The envirorrnental implications of rrovin;) truckloads of soil to the
site are insignificant within the context of the environmental
~rovement af forded by tne remedial action, the existing adjacent
land uses, and the existing local traffic which includes movement of
truckloads of soil.
.
6.
Pending, other than temporary storage, will not result fran the
construction of the dikes: thus, there will be no increased infiltration.
Dikes will retain stor.m water runoff fram the site for treatment, if
necessary, and subsequent disposal to the local municipal wastewater
treatment system.
7.
Stablization is necessary to provide load bearing capacity for
equipment used to emplace the cap, for the cap itself, and for future
operations and maintenance activities. Testing has demonstrated that
for the extreme worst case, leachate quality will not be significantly
~acted by waste stabilization.
8.
Raising the site above the lOO-year floodplain is the most oost-
effective method for meeting the objective of preventing migration or
washout of wastes fran the site during a lOo-year flcx:x:1. Thus, raising
the site is not inconsistent with the National Contingency Plan.
II. Ocmment - £PAIs analyses of appropriate remedies fail to identify and
quantify any danger to the public health, welfare, and the envirorment.
Jesponse
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According to section 300.68(e) (2) of the NCP (source control), remedial
actions may be appropriate if a substantial concentratioo of hazardous
substances remain at or near the area where they were originally located
and inadequate barriers exist to retard migration of substances in the
envirorment. This is exactly the condition at the Bi<>-Ecology site.
The Investigation Report documents the following conditions:
1)
Significant waste quantities containing high concentrations
of metals, cyanides, and aranatic organics are present at the
Bi<>-Ecology site.
Seventy-five percent of the site is located within the 100-
year flcx:x:1plain and susceptible to severe flcx:x:1ing.
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3)
Migration pathways and migration mechanisms are present at
the site for potential significant long-term waste migration
to surface and subsurface waters and adjacent are~s.
Surface contamination in off-site drainage ditches and
traces of subsurface contamination in the quaternary
gravel aquifer beneath the site.
4)
5)
Waste migration to date has been primarily restricted to
on-site locations with the exception of past surface offsite
migration caused. by flooding.
6)
Target receptors currently impacted are adjacent land areas
(dead and dying vegetation) and surface waters.
'!'he NCP further states that if source control remedial actions are
determined to be needed, these actions may include alternatives to
contain the hazardous substances where they are located or to eliminate
potential contamination by transporting the hazardous substances to a
new location. It was determined by mvR and EPA, based on the findings
of the Investigation Report, that on-site source control remedial action
is needed to adequately protect public health and the environment.
.
The criteria developed in section 300.68(e)(2)(i) were assessed in the
Investigation/Feasibili ty Report. '!hey are the following:
1.
The extent to which substances pose a danger to public health, welfare,
or the environment include the following factors:
A.
The ~ulation at risk was discussed in general terms throughout
the report and is delineated below:
1.
2.
3.
4.
5.
Adjacent cammercial auto salvage workers.
tcwnstream catmercial surface water users.
Residents of a nearby mobile heme park.
Plants and anUnals.
Future shallow groundwater users.
i
B. J!m:>unt and form of the substance present:
cubic yards of sludges with:
Approximately 40,000
1.
2.
3.
4.
Containerized wastes, sane of unknown description.
Perched water in and around the wastes.
Large quantities of jelly-like waste of a flowing
Contaminated soil.
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C.
Hazardous properties of the substances include:
l.
2.
3.
4.
5.
Poisons - OJ, Arsenic, and various rretals.
Carcinogens - PCB, chrome, chlorinated Benzene.
Corrosives - containerized acids.
React i ves - rn, Red phosporous, picric acid.
Priority pollutants.
D.
Hydrogeological factors are discussed extensively in the
Investigation and Feasibility Report. The alluvial deposits have
a secondary structure of cracks and fissures capa~le of transmitting
contaminants.
E.
Climatic factors of concern are:
.
l.
2.
Rainfall causing flooding.
Dry periods causing dessication of soils and alluvium.
.
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2.
Contaminant migration at the present time is restricted to the vicinity
of the site. The only adequate barrier providing containment at the
site is a natural geological formation, the Eagle Ford shale.
3.
EPA and TDWR experiences and approaches used in similar situations
are limited, b.Jt generally tend tCMard effective containment.
4.
Environmental effects and welfare concerns were discussed in the
contaminant migration and target receptors sections of the Investigation
Report.
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The NCP has no specific requirement to definitively address the extent or
likelihood to which identified substances could migrate from their
current location, particularly wi thin the context of how quickly they
would DOve, and in what concentrations they woold be found, if they did
DOve. The developrrent of an accurate and calibrated contaminant migration
nodel is unnecessary for a source control situation.
-
The overriding objective or performance standard is to "control offsitei
.migration of wastes I:¥ surface and subsurface pathways". This objective
along with others stated in the Feasibility Study all"", the detemination
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III.
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COmment - EPA was required to prepare an Environmental 1mpact Statement
Respx1se
EP~ is not required to prepare an Environmental Impact Stat~nt for
actions taken at Superfund sites. However, the remedial investigation/
feasibility study prepared at this site addressed the human health
and environmental impacts of various response options, their feasibility
and reliability, and the costs of each alternative. In addition, EPA
has provided an opportunity for public review and comment on EPA's
evaluation of the site and of the range of remedial o?tions considered.
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I.
Response to ERM-Soothwest, Inc.
CCJTIJ'Tents on the
Proposed Remedial Alternative
for the Bie-Ecology Site
Grand Prairie, Texas
Response to Major CaT'IJ'Tents (frcm ERM report sumrre ry)
1.
The data demonstrate that the gravel aquifer is subject
to contancination from wastes at the site migrating through the
secondary structure of alluvial deposits. The secondary
structure has been reported in geotechnical observations in
the Texas Department of Water Resources (TDWR) Bie-Ecology file
39009 (National Soil Service, 1978) and by Wbodward & Clyde Con-
sultants (weC) Site Investigation and Remedial Reports for the ~
Bie-Ecology site. The existence of secondary structure is
further supported by subsurface contaminant distribution in
subsurface soils and groundwaters. Geotechnical laboratory data
further supplement the data.
2.
Consistent with a permanent remedy, stabilization of the wastes
is required in order to provide load bearing capacity. This load
bearing stability is required for equipment used to emplace a cap,
for the cap itself, and for future operation and maintenance con-
siderations. During the temporary closure, the investigation phase
of the project conducted by the TDWR, and the Initial Remedial
Measure conducted by the Environmental Protection Agency (EPA),
problems were encountered regarding insufficient load bearing
capacity for equipment at the site.
As a secondary function, waste stabilization is expected to
provide sore control of leachate generation. In the Feasibility
Study, leachate testing was conducted using high shear mixing
which resulted in the worst case leachate concentrations to be
expected under the field conditions.
...
3.
The effect of Joe Poole Reservoir being constructed upstream
fran the site was not taken into account when determining
floodplain elevation at the site. It is the understanding of
TDWR and EPA that when completed in 1985 or 1986, the reservoir
should result in a lower 10o-year floodplain elevation. The
design of the remedial alternative will take this effect into
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4.
The Feasibility Study objective "Prevent migration of wastes
during a lOO-year floc::xj" is indeed procedurally correct
and should replace the objective, "Raise the site above the
lOO-year floc::xjplain elevation." However, this will not have
a significant impact on the final remedial alternative.
5.
Erosion considerations will be examined in detail during the
design of the remedial alternative. The need to raise the site
above the IOO-year floc::xjplain follows only as a cost-effective
component of a remedial alternative which meets the objective
of preventing mdgration of wastes during a IOO-year floc::xj.
6.
TDWR acknowledges that cost savings may follow fram considering
the waste management practices for the northeast corner of the
site as proposed by ERM-Southwest, Inc. These waste management
practices will be considered during the design phase of the
project.
~
7.
The remedial measure proposed by ERM-Southwest, Inc. is not
acceptable as explained below. The ERM proposal does not
address:
a.
b.
Treatment of special wastes:
Stabilization of waste sludges tor load bearing capacity
and elimination of perched water;
Control of subsurface contaminant migration through the
secondary structure of the older alluvial deposits: and
Management of rainfall runon and runoff during site
construct ion.
c.
d.
Response to Canments (ERM report section two)
1.
Deep Slurry Trench
The secondary structure of the older alluvial deposits is
supported by data and references in both W:C project reports.
This support includes five separate rot correlated features
which encompass geotechnical observations, contamdnant dis-
tribution in soils and groundwaters, and geotechnical labora-
tory data.
~
a.
The boring logs in Appendix A of the Site Investigation
Report contain references to secondary structuring in the
older alluvium. This is a geotechnical observation by a
geologist on the professional staff of W:C. (ERM does not
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b.
Another geotechnical oQservation is made in reference to
the vertical transmissive paths of water through fissures
and slicken sides of the stratum on pages 29 and 42 of the
Investigation Report. '!his in reference to a report
(No. 4-78016-1) undertaken by NFS/National Soils ~rvices,
Inc., entitled "Phase I Geotechnical Investigation Indus-
trial Waste Landfill Bio-Ecology Systems, Inc., Grand Prairie,
Texas. " It should be noted that this report was undertaken
in April 1978 and has been a part of the public record of
TDWR file No. 39009 for Bio-Ecology since at least February 20,
1980. The report is an investigation ot subsurface con-
ditions at the proposed industrial waste landfill site to the
west of the site which was never const~~cted.
The significant statement of the report with regard to
secondary structure resulted fram a dramatic and unusual
drilling phenomenon encountered in all six field borings
undertaken.
~
The drilling method used was a rotary wash technique and the
phenomenon is repeated below in its entirety from page 5
of the NFS report.
-There was no drill water return'*' belOool depths of 8.0 feet
in borings B-3, B-4, B-5, and B-6, below 10.0 feet in
bori~ B-1, and belOool 21.0 feet in boring B-2. All
water disappeared into cracks and fractures in the
undergro..md formations. Previous experience with the
ty~ of c lays encountered has shOooll1 that during periods
of rainfall and high ground noisture, the undergro..md
fractures and joints remain closed and impermeable.
Hc::Mever, if the clays are peDnitted to lose moisture,
or if the water table is extrerrely deep as it is in
this area, large cracks develop and the clays exhibit
substantial peDmeability.'*' The cracks may extend
large distances in both horizontal and vertical direct-
ions, and can be either continuous or discontinuoos."
..
"The major problem which will occur during the develop-
ment of the site as a landfill is to elUninate the
numerous large cracks and fissures which are generally
present below an approximate depth of 8.0 feet as
evidenced by the large water losses experienced during
the drilling operations. only because of the cracks,
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c.
Contaminant distribution in the subsurface soils is dis-
cussed on page 32 of the investigation report. W:C states
on p~e 33 that "the elevated test results shown
in Table 8 at depth may be indicative of the leadi.n;J edge
of waste migration". This is the type of contaminant
distribution expected frc:rn contaminant migration in a
secondary structure.
d.
Contami nant distribution in the groundwaters is discussed
on pa;je 33 of the Investigation Report. The data results
of Table 6 are discusse:J and the followiJ1;J pattern is
revealed. "Data for on-site wells show highe~ levels of
nickel, TOX, and TOC than for off-site wells, with lead
and nickel exceeding EPA standards". This is coupled with
the statanent that "GraJOOwater data for wells off-site
indicate lead arrl nickel exceed EPA standards, while cajrnium ~
levels are just sl1ghtly elevated". Frc:rn this, W:C further
states that "Shallow groundwater flow in the nodern alluvial
deposits is expected to be adjacent stream beds and low areas,
plus a portion of the flow vertically dowrward toward the
gr avel layer".
e.
Further eviden:e of secondary structure follows frc:rn an
analysis of the geotechnical data itself. Page 22 of the
investigation report discussed geotechnical testirQ and
states that the data were used to develop the shallow
stratigraphy. The geological settirQ is also described
on pages 3-7 of the investigation report. W:C considers
these fa::tors in concludirQ on p~e 42 of the Investigation
Report that:
The older alluvial deposits that underlie the modern
sediments were deposited in a floodbasin environment
and are exxnposed of low to high plasticity clays. A
secondary soil structure consistirQ of slicken sides
am fissures due to cyclic shrir*~e and swellirQ
during seasonal changes is present in the stratum.
~
It is comon krx:wledge arong soil scientists, civil
e~ineers, and others that noisture loss in clays causes
shrirKa;Je. At the surfa::e, this is eviderx:ed by distinctive
visible cracks in the soil. 'Ihese were pointed out to
ERM personnel in a site visit on August 25, 1983. These
cracks result fram field soil moisture which is signifi-
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"The site is situated within the rrodern floodplain of
Mountain Creek." "The surficial sediments at the site are
recent alluvial deposits of Old Mountain Creek and were
depcsited in a floodplain meander. II These statements cOOle
fran pcges 3 anj 5, respectively, of the Investigation Re-
port. Thus, at the time of deposition in a floodplain
environment, it is safe to assume that the alluvial deposits
haj a significant moisture content.
.
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Now consider the geotechnical test results of Appeooix C
of the Investigative Report. The two determinations of
interest are the field percent Iroisture and the plastic
limit of toe Atterberg Limits series. These data are listed
in Appen:hx C aoo are yrCiiJhically displayed on the boring .
logs of Appendix A for easier visualization. The field
m::>isture is the actual percent moisture of undisturbed
sanples secured anj sealed in the field for testing in the
laboratory. The plastic lirni t measures the moisture con-
tent of the soil at which the sClTlple crumbles when rolled
into 3/B-inch threads.
~
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Canparison of the plastic limit an:j moisture content for
the alluvial d~osits at the site reveal a significant
feature. The bulk of the data reveals a moisture content
which is near or below the plastic limit. A total of 23
data pairs allOt\' for the cx:mparison. Out of the 23 pairs
for the alluvial clays, 19 reveal a moisture content within
the rarye of concern. If the surface pairs are disregarded,
and the alluvial clays are exanined, only one sClYlple pair
shows a moisture content which is significantly higher
than the plastic limit.
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.
.
Thus, the alluvial materials were deposited in a floodplain
manner which would give them a higher moisture content. As
the deposits were dessicated to a lower field moisture, the
moisture chanJe caused shrir*age. '!he shririrt
the \cC Investigation Report Cooclusion that secoooaLy structure
is present ard that migration pathways an:] migration mechanisms are
present at the site for potential significant lOOJ-term waste
migration to subsurface.
On p~e 2-2 of its report, ERM states its confusion as to how wx
coocluded the existence of slight contanination of grourowater on
paJes 33 an:] 34 of the Investigation Report. These data in Table
6 of the Investigation Report clearly ShCM EPA standards as bein;;;!
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ERM confuses the wee discussion of subsurface soil contamination
which summarizes the soil metals data in Table 2-1 and concludes
on page 2-3 that "the heavy metals content of the downgradient
oorings are essentially the same as the uwradient ooring." ERM
simply refers to soil variability and ignores a distinctive trend.
Soils metals downgradient increase in all but one case. For the
data present in ERM Table 2-1, soils metals increase downgradient
A6 percent of the t irne (1\ of 7) wi th an average increase of
82.7 percent. If the data were variable, there should be no trend.
Other soils metals trends noted by wee are dismissed by ER~ as
"probably" a natural geologic phenanenon withoLJt an explanation or
even a supposition and with no supportin~ data.
t
FRM discussion of quaternary gravel water quality differs fram
~e basically in the interpretation of contamination source. ERM
apparently considers upgradient and downgradient somewhat fixed
and does not recognize the possibility of groundwater contamination
fram the hazardous waste site itself. ~e (on page 42 of the
Feasibility Report) recognizes that "groundwater flow is subject to
change depending on site conditions." Thus, the historical down-
gradient well, ~6, is not necessarily downgradient at all times.
\<:l:e also recognizp.s (on page 33 of the Investigation Report) that
"shallow groundwater flow in the modern alluvial deposits is ex-
pected to be from onsite (within fenced area) to offsite (out-
side of fenced area) to adjacent stream beds and 101.1 areas, plus
a portion of the flow vertically dOl.'nward toward the remnant
gravel layer." The contaminant migration could easily be extended
in the modern alluvial deposits to a point updip (north) of the
u~radient well ~l. '!hus, the ERM conclusion on page 2-7 that
"this shallow aquifer is not suitable use for human consumption
even if the Bio-Ecology site did not exist," is not fully
supported .
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ERM properly noted that the Bio-west monitor well was screened for
almost its entire length and that it should be plugged as a part of
the remedial plan.
Although the wee report states that the residential development
is unlikely within certain distances of the site, the TDWR and the
EPA have no control over land developnent. If certain improvements
were made, the land could be developed.
The reference in the Investigation Report (page 46) regarding low
yield is wi thin the context of central municipal supplies. The con-
tamination referenced is likely to be from bacterial or other
nan-hazardous contamination as the reference (Morgan, 1965) refers
to the drilling to underlying artesian sands in the 1880's tbme
frame. It in no way inplies that the groundwater cannot be used
by individuals.
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Public desire to contain t~e contamination at the site was
expressed at the public meeting regarding the site conducted
on December 15, 1983, in Grand Prairie. Additionally, an
adjacent auto yard owner/operator expressed an interest to use
shallow groundwater. One shallow well has been documented in
the area. Thus, within the context of a p;rmanent solution,
protection of the shallow aquifer is clearly appropriate.
2.
Stablization of Waste
The remedial alternative selected by EPA includes waste
stabilization in order to provide load bearing capacity.
This load bearinJ stability is required for equip.nent used to
emplace a cap, for the c~ itself, and for future operation
and maintenance considerations.
Leachate testing in the feasibility report was undertaken as
a "worst-case" test. This was to ensure that stabilization
did not significantly impair leachate quality. The test used
high shear mixing in order to approxllnate the highest leachate
concentrations to be expected under field conditions. (Feasi-
bility Report pages 22, 23). ERM has properly noted that sta-
bilization "could" increase the role of contaminant migration
fran the waste. However, this pass ibi li ty is very anall be-
cause the "worst-case" testing does not significantly
increase leachate concentrations.
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The waste stabilization was undertaken to "detennine the optimum
ratio of cement flue dust necessary to solidify the sludge."
(Feasibility report page 20). The waste sampling portion of the
W:C investigation report (pages l3-17g) is replete with
references regarding the stuctural properties of the waste.
Page
Ccmnent
14
The (chrome) pit was under standing water during
the site investigation and was of the consistency
of je lly . Therefore, sanpling was limi ted to the
northern half of the chrane pit.
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15
It was found that the proposed grease trap con-
tained 14 feet of jelly-like sludge at Pit 5/6.
The adjacent southern lagoons were filled with
water and were of low load bearing strength.
Excavations were made next to the lagoons.
l''Ollowing a determination of adequate support for
the backhoe, pit 17c was dug.
pit 4A:
Pit 4B:
Milky perched water.
Pit caved in.
Pit l6A: Much perched water, dnrns, trash,
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l7c
Pit 17C: --Drums, perched water at 2 feet
Pit 17D: Perched water
(Various drums in several pits)
17d
Pit 21C:
Pi t 28:
Pit 28A:
Caved in
Perched water
Rubble over trees and vegetation
17f
Pit 49A, 50A, SOB (water under tUmber mat)
t
The inability of the wastes to support a cap has been demonstrated
on at least three occasions. First, durin~ the temporary site closure,
the contractor (Hancock) experienced proble~s emplacing a cover
over sludges. The sludges "erupted" into the area of tanks T2, T3,
and T4. (This was mentioned to ERM personnel during a site visit
on August 25, 1983). Other sludges slumped and were unable to main-
tain a crowned slope. Second, during the waste sampling under- ~
taken by Rollins, the ~ onsite investigator noted the backhoe
sinking into sludge at least once to the point that tracking
slipped and the bucket had to be used to "pull" the backhoe out
of a sinking situation. Third, during the initial remedial
measure, EPA's contractor (Coastal Environmental Corp.) experi-
enced similar problems wi th certain areas being unah1e to support
remedial equipment. Thus, the need for waste stabilization has
been adequately demonstrated.
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The degree to which the waste is stabilized will be further speci-
fied in the design phase. The feasibility testing discussed in
the feasibility report for waste stabilization is routinely used
by the hazardous waste management professionals at Rollins.
Acceptable test results were recatrnended based upon their broad
experience base in dealing with similar hazardous wastes. Their
testing goal is stated on page 21 as one which is "sufficient
to impart load bearing stability to the mass."
Actual numerical design standards to meet this performance
criteria have not been promulgated. The feasibility stability
testing has demonstrated the feasibility of stabilizing the
Bio-Ecology waste up to the 500 lbs/in2 range. The proposed
ERM load bearing capacity of 450 lbs/ft2 is much less and is
based only upon the weight of a clay cap and does not consider
the weight of vehicles used to emplace the cap. ERM has in-
cluded no factor of safety for testing variability or construct-
ion error. Yet it prcp:>ses to cover the undisturbed waste
without p~iding a technical basis to demonstrate that its
method is either feasible or reliable. No assurances of long-
tenn performance of the ERM capping approach have been provided.
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'l11us, consistent with a permanent remedy (NCP 300.68a) ,the lack
of waste stabilization is not acceptable. Although the degree
of stabilization need not be as high as 500 Ibs/in2, stabilization
for load bearing support is required and will be further refined
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in the design phase once the methods of construction and
types of equipment are specified. Failure to deal with the
significant amounts of perched water at the site is another
unacceptable feature of the ERM proposal.
ERM has provided comments on several factors regarding the wee
discussion of waste permeability and leachate quantity. These
comments are duly noted. However, the wee position is not
without merit and as a secondary function, waste stabilization
is expected to provide ~proved control of leachate generation,
particularly in light of the current saturated conditions of the
waste due to extensive perched water.
3.
Effect of New Dam on Floodplain
The ERM ccrrrnents regarding the new Joe Poole reservoir and its
potential to significantly reduce the downstream flooding
effects along Mountain Creek are duly noted. The revised
information will be used in all design aspects regarding the
site.
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4.
Floodplain Objective
ERM has properly noted that the floodplain objective should
have been to prevent waste migration during the 10o-year floods.
However, it is not likely that a less costly remedial plan
could have been developed. Even under current 10o-year flood
conditions, and with additional topsoil as recammended by
ERM, the wee cap meets the revised objective for a 1984 estimated
construction cost of $313,430. The ERM proposed cap must have
a geofabric to be emplaced according to ERM, and since it will
be below the flood level, it must have a synthetic membrane
and cover materials to prevent uplift of wastes. O1ce these
considerations are made, the ERM cap design, if feasible,
would meet the design objective but at an estimated cost of
S349,000.
5.
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Effect of 100-Year Flood on the Cap
ERM CO'TI'nents regarding the effect of the 10o-year flood on the
cap are duly noted. these ccmnents will be considered in
during the final design of the cap. Furthermore, because the
area being raised is snall when canpared to adjacent areas in
the floodplain, raising the site to the 10o-year floodplain is
not expected to have an adverse impact on the surrounding
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6.
Cost for Smaller "L" Shaped Cap Versus Larger Rectangular
Shaped Cap
The ERM ccmnents regarding an "L" shaped cap are duly_noted and
will be considered in the design phase of the project.
7.
Critique of the Proposed No. 6 Cap Design
ERM comments regarding inadequacy of the proposed cap under
Alternative 6 generally ignore the provision for routine
operational and maintenance (0 & M) activities. TIJ.\~, as a
condition of its Cooperative Agreements with EPA, has assured
future 0 & M.
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As a result, damage to the prcposed cap or the cap to be
implemented for the chosen alternative (No.8) froo erosion, ~
dessication, and root penetration will be prevented or rni tigated
~ a regular 0 & M schedule. Erosion damage will be repaired.
Dessication will be minimized by watering as necessary. Root
penetration will be minimized by allowing only grasses to
grow on the site. A regular mowing schedule will prevent the
development of trees on the site. In concert with the proposed
remedial action, these 0 & M measures will prevent the release
of encapsulated materials. ERM comments regarding the thin
soil layer of the W:C prcposed cap are not without merit,
however, and minor changes of this aspect may be considered
during the design phase of the project.
,.
Any design which includes extension of the cap onto adjacent
property is not acceptable because of the eaS€!Tents required.
EPA and TDWR have no cootrol over adjacent land uses and as a
result cannot reCCJ'l'll1end any alternative which impinges upon
adjacent land. With a lower design elevation, due to the Joe
Poole reservoir, slopes and subsequent erosion will be minimized.
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III. Response to ERM Recarmended Alternative (No.IO)
1.
Features
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Although the ERM prc:posed alternative shows an innovative
approach and presents some interesting design features, it is
not an acceptable substitute for either wee Alternative No.6
or No.8. It fails to meet objectives for the site which have
not been questioned by either ERM or Tharpson and Knight. It
also fails to comply with RCRA technical regulations for on-site
disposal of hazardous wastes. .
a. An "L" shaped slurry trench is acceptable bJt DUst be
extended to a 60 feet depth (previously discussed).
b.
'!he proposed ERM cap is not reliable due to poor load
support capacity (previously discussed).
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Surface shaping and fiU as proposed by ERM is possibly
acceptable, but once again, is probably not feasible due
to poor load support capacity. Additionally, no provision
is made to control stormwater during constrUction.
Four groundwater monitoring wells may not be sut{lcient
to detect all contanrinated groundwater plumes, and would
require further consideration.
The ERM alternative has no provision to treat the special wastes as
outlined in all wee alternatives. Neither ERM nor Thompson and Knight
have protested this provision contained in the site specific response
objectives, but this element of work is omitted from the ER~ plan.
Since the ERM report does not demonstrate or establish that
feasible and reliable practices are being employed, it is
impossible to establish that the ERM alternative effectively
blocks pollutant migration pathways. Furthermore, the ERM
alternative fails to meet several criteria of the National
Contingency Plan (NCP).
2.
Function
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Section 300 .68(a) of the NCP calls for remedial actions to be
consistent with permanent remedy to prevent or mitigate the
migration of hazardous substances into the envi~nment. The
ERM proposal is deficient in this aspect because it does not
address:
b.
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3.
Cost
a.
Treatment of special wastes (cyanide and arsenic):
unlike the selected remedy, the ERM alternative
does not provide for stabilization and neutralization.
Stabilization of waste sludges for load bearing capacity
and elimination of perched water:
Cont~l of subsurface contaminant migration throogh
the secondary structure of the older alluvial deposits: .
the shallOtl slurry wall proposed by ERM does not ~
extend to an apprcpriate stratum, and thus might
allOtl groond water migration into and throogh the
site.
d.
Management of rainfall runon and runoff during site
construction.
Althoogh the ERM prcposal is less costly, it has not been
dencnstrated to be as feasible and reliable and it does not
as effectively mitigate the problems as well as the cost-
effective or the selected remedy.
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4.
Discussion
As pointed out by Thcrcpson and Knight, the NCP presents
criteria for assessment in formulating source control
remedial actions in Section 300.68(e)(2). None of these -
criteria were adequately considered by ER~ in the develop-
ment of their prcposal. For exa:Tlple, Subheading II.l.b. of
this reference calls for an assessment of the extent to which
substances have nrigrated or are contained by natural barriers.
The only adequate natural barrier at the site is the Eagle Ford
formation.
The ERM proposal recognizes the need for a shallow slurry
wall but even in light of the seconQary structure of the older
alluvium, they fail to recognize the need to elimdnate potential
migration by either the use of a landfill to contain wastes or of
a deep slurry wall keyed into the Eagle Ford. The incremental
cost of this activity is worth the incremental benefit of elimdnat-
i09 uncertainty and is consistent with a permanent remedy for
the site.
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wee's method of dealing with stormwater during construction is
acceptable waste management practice which is critized by ERM.
Since ERM fails to manage stormwater during construction, it
is reasonable to expect significant adverse effects during
implementation which is inconsistent with Section 300.68(h)(2)
of the NCP.
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Response to
Air Force Comments on the
Prcposed Remedial Alternative
for the
Bic-Ecology Systems, Inc., Site
Grand Prairie, Texas
1.
Canrrent
The report's recommended alternative (Number 6) appears to provide
a good balance between environmental/health considerations and cost
of remedial action. H(J.olever, the elimination of cheaper alternatives
shoold be explained in detail rather than to eliminate the,i\ "based
on performance". We say this because all eight options pose Irn.Jch
the same risks to the environment after completion of the remedial
action.
Response
At
Providing a good balance between environmental/health considerations
and cost of remedial action is certainly the goal in selecting a
remedial alternative. Alternative Six minimdzes risk to the
environment and thus, based upon performance, Alternative Six
was recanmended originally. The less expensive alternatives were
eliminated because they did not provide risk minimization for the
Quaternary Sands. The deeper slurry wall provides ncre reliability
over less costly alternatives as it provides for risk ndnimization
for the Quaternary Sands, thereby assuring better performance.
However, the slurry wall is susceptible to leakage over time due to
possible long-term increase in permeabili ty. In contrast, synthetic
liner systems, combined with leachate collection are expected to be
effective indefinitely given the nature of wastes presented at the
site.
2.
CCJ'IUtent
The design life used for the comparison of alternatives was not
stated. This is an important fact since the desirability of the
various alternatives will shift by varying the design life. We
note that RCRA facilities have a 30 year design life.
~
Response
A design life of 30 years was used in the report (pp. 4, 42, 55).
This design life is analogous to RCRA facilities.
3.
Carment
Removal of all contaminants fran the site is .an alternative that does
not appear in this final cut. If the design life of the recamended
alternatives was 100 years, would the alternative to rerove all
contaminants from the site be practical? At what point would removal
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Response
If the design life of the recamended alternatives were 100 years,
the alternative to remove all contaminants fram the site still
would not be economically practical. This is because the present
worth of the annual 0 & M costs (approximately $100,000) ~ould still
represent a relatively small portion of the total cost of the pro-
posed remedial action (approximately $2,700,000). This coopares
with a cost of $4,470,000 to remove all contaminants from the site.
The point at which reJn:)val of contaminants fran the site would be
economically practical is uncertain. It is In:)re than 100 years
and thus not within the planning range of the Texas Department of
Water Resources (m']R).
4.
CO'TIJ'rent
o & M costs are only extended for 30 years. What will be Air Force
obligations during and after the 0 & M period.
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Response
It is the intent of the TDWR to recover 0 & M funds from responsible
parties, either in a lurrp sum or a continuing payments basis. The
Texas Water Development Board has instructed the Exeo.Jtive Director to
recO'TlJ'rend state legislation concerning this subject. This effort
is being developed at the current time.
5.
CO'TIJ'rent
The cost of the slurry wall is in general agreement with the attached
Pollution Equipment article for a 60' wall with fair soil conditions.
Response
Your ccmnent on the appropriateness of slurry wall costs is hereby
acknCMledged.
6.
C~~ .
Page 5 of the "Remedial I~lernentation Alternative Selection" indicate~
the State's partial site closure included burying containerized waste
on site. These containerized wastes were presumably 55 gallon drums.
If the burying of these wastes on-site significantly increased the
cost of the ultimate clean-up, then the State's share of the cleanup
should be increased.
Response
The wrying of containerized waste onsite during the partial site
closure is not expected to significantly increase the ultimate
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the site and would have to be remedied in any event. During the
waste sampling phase of the field investigation, buried drums were
encountered in a random fashion throughout all landfilled areas of
the site. It should be noted that the partial site closure has
significantly minimized the risk of release during the in~erim
period preceding implementation of a final remedial alternative.
7.
Canment
The "initial remedial measure" (Page 50) includes the rerroval and
disposal of approximately BO,OOn gallons of hazardous liquids .and
sludges. If this has not yet occurred, it would be preferable to
incinerate the material, rather than moving it to another landfill,
only to run the risk of having the problem reoccur in the future.
Response
~
The initial remedial measure has already been canpleted. Sane of
the liquids removed contained a significant percentage of water and
were not incinerable. It is the understanding of TDWR that where
possible, PCB liquids removed fram the site have been or will be
incinerated .
R.
Ccmnent
There doesn't appear to be anything included in the alternatives for
removal of significant amounts of off-site soil in the stream bed
should contamination (heavy metals, Jrost probably) be detected. Are
we truly finished with Bio-Ecology once the waste is stabilized
and the site capped, or are these costs just the beginning?
Response
The removal of offsite soils from the streambed was not included in
the alternatives because significant contamination was not detected
in these soils. The alternatives focused mainly on source control
remedial measure since the hazardous substances located at the site
have not migrated significantly beyond the ~diate site area.
With the exception of routine 0 & H, once the remedial .alternative
is ~lemented the closure of the site should be canplete.
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9.
Ccmnent
The "Evaluation Results" (Page 11) show a "degree of significance"
far in excess of what is actually the case for a relatively subject-
ive process. One simply cannot quantify "potential hlnan health
impacts" to four significant figures. O'1ly cost is a solid number,
and even then, it is a subjective decision that 250 points out of
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lowest cost alternative, Number '4, didn't receive the maximLITI
number of points, rather than 175 of 250. If there are additional,
feasible alternatives, they should be discussed. The table would be
far more credible with two significant figures for each ca!egory.
Response
The Evaluation Results (Table 13 of the Feasibility Report) show
several significant figures due to the development of soores and
the averagi~ of these scores. Scoring began by considering each
of the categories on an absolute scale from 1 to 10, which
essentially represents only one significant figure. Allocation of
short-term and long-term effects, consideration of the total points
for each category, and averaging six total scores yield several sig-
nificant figures. The scoring process is described on page 64 of
the Feasibility Report and evaluation sheets are included in
Appendix D. '!he lowest cost alternative, Number 4, received the
rrost points of any alternative in the cost category. TDWR and
EPA acknowledge that the process, like many others, is subject to
a certain amount of subjectiveness. WOodward & Clyde Consultants (WCC)
developed the process and have routinely used it successfully in
their work with other clients. TDWR and EPA do not endorse the
procedure as a fail-safe selection p~cess, but be1ive that the
selected remedy is consistent with the NCP and necessary to protect
human health and the environment.
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10.
Ccmnent
In regard to the suggested Ground Water Monitoring Program, (1) four
rronitoring wells may not be sufficient to pick up all contaminated
ground water plumes and (2) Monitoring for only 13 contaminants
appears inadequate considering that organics and PCB's were also
disposed of at the site. It would be prudent to periodically
monitor for specific volatile and purgeab1e organics in upslope
and site nDnitoring wells.
Response
The ground water nDnitoring program is described on pages 42 and
43 of the W:C Report and in the EPA Addend\J1\ 2. The 13 parameters
listed in the Addendl.lTt are minimiml.lTt testing requirements required
in addition to ~riority pollutant analysis for upgradient and
downgradient wells. As stated in the Addendum, the program will
include the installation of groundwater monitoring wells of sufficient
number and at the appropriate locations and depths to yield repre-
sentative groundwater samples fran the quaternary aquifer. The
exact parameters will be determined in the detailed design for the'
plan.
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11.
Canrrent
There is no explanation for the weighting applied to the numerical
factors which makes it difficult to determine if the differences in
the values obtained for the various options (Page 11) is significant.
The cost variances are significant, and an explanation of the rating
system would aid in the evaluation of the alternatives.
Response
An explanation of the weighting applied to the nllilerical factors
is included on pages 52-53 and 61-64 of the wee Report.
12.
CCJ1T!ent
The selected option appears redundant. The waste is fixed in place
and then a clay cap is applied. Both of these techniques are used
to control the downward ~gration of contaminants. If the clay cap
is correctly applied, fixation shouln not be required. The converse'
is also true. The slurry wall, intended to prevent ~gration of
contanrinants down the groundwater hydraulic gradient, appears to be
overdesigned. The only benefit to be gained frc:rn the downstream
portion of the slurry wall i5 contai~nt of water which has
intruded frc:rn the surface of the site. If the clay cap has been
correctly installed, there should be no such intrusion. A slurry
wall installed around the upgradient half of the site would appear
to be an effective approach. Please explain.
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Response
The reCCJrltended c::ption considers several integrated factors in
achieving a long-term reliable remedial alternative. A clay cap
at the site will provide the coverage of waste required to prevent
direct contact of wastes by intruders, surface ~gration of wastes
by weathering, and will provide sane degree of control over the
downward migration of contaminants. Stabilization of wastes is
required in order to provide loadbearing capacity for equipment
used to emplace the cap, for the cap itself, and for future
operation and maintenance considerations. As a secondary function,
waste stabilization is expected to provide Sate inproVed control
of, leachate generation. Due to the secondary structure in the
alluvial deposits, a slurry wall would serve to ensure control over
subsurface migration of contaminants. A partial slurry wall would
not be as effective an approach as it would not provide containnent
of contaminants. The optian selected by EPA essentially replaces
the slurry wall with a liner and leachate collection system to
contain wastes on-site. EPA feels that the selected c::ptian,
althoogh slightly ncre expensive than the option recarmended
previoosly, is ncre reliable over the long term.
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