United States Office of
Environmental Protection Emergency and
Agency Remedial Response
SEPA Superfund
- Record of Decision
Crystal Chemical
(Amendment), TX
EPA/ROD/R06-92/071
June 1992
PB93-964201
o
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NOTICE
The appendices listed in the index that are not found in this document have been removed at the request of
the issuing agency. They contain material which supplement, but adds no further applicable information to
the content of the document. All supplemental material is, however, contained in the administrative record
for this site.
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50272-101
REPORT DOCUMENTATION
PAGE
1. REPORT NO.
EPA/ROD/RO6-92/071
3. Recipient-* Accession No.
4. Title and Subtitle
SUPERFUND RECORD OF DECISION
Crystal Chemical (Amendment), TX
First Remedial Action - Final
5. Report Date
06/16/92
6.
7. Authors)
8. Performing Organization RepL No.
9. Performing Organization Name and Address
10. ProjectTTask/WorkUnltNo.
11. Contract(C)orGrant(G)No.
(C)
(G)
12. Sponsoring Organization Name and Address
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
13. Type of Report & Period Covered
800/000
14.
15. Supplementary Note*
PB93-964201
16. Abstract (Limit: 200 word*)
The 24.4-acre Crystal Chemical site consists of a 6.8-acre abandoned herbicide
manufacturing facility (referred to as the onsite area) and 17.6 acres of affected
surrounding properties (referred to as the offsite area) in Houston, Harris County,
Texas. The site, which lies within the 100-year floodplain of an adjacent flood
control channel, overlies a shallow aquifer system. Surrounding land use is commercial
and industrial. From 1968 to 1981, herbicides, including arsenic compounds, were
manufactured onsite. During that time several structures, four evaporation ponds, and
many storage tanks were utilized in site operations, and drums of raw and finished
product were routinely stored in the open. During transfer of raw materials from rail
cars, onsite soil was contaminated by herbicides spilled from drums. Contamination of
offsite soil and sediment was a result of periodic flooding, which caused arsenic-
contaminated onsite wastewater to move offsite. In 1981, the site was abandoned, and
approximately 99,000 gallons of chemical liquids in a storage tank and 600,000 gallons
of wastewater in the evaporation ponds were left onsite. Emergency removal actions,
conducted intermittently by EPA from 1981 to 1988, included removing chemical liquids
and wastewater, temporarily capping the site, dismantling and decontaminating site
(See Attached Page)
17. Document Analysis a. Descriptors
Record of Decision - Crystal Chemical (Amendment), TX
First Remedial Action - Final
Contaminated Medium: Soil
Key Contaminants: Metals (arsenic)
b. Mentffiers/Open-Ended Terms
c. COSATI Reid/Group
Availability Statement
19. Security Class (This Report)
None
20. Security das* (This Page)
None
21. No. of Pages
34
22. Price
(SeeANSI-Z39.18)
See Instructions on Reverse
OPTIONAL FORM 272 (4-77)
(Formerly NTIS-35)
Department of Commerce
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EPA/ROD/R06-92/071
Crystal Chemical (Amendment), TX
First Remedial Action - Final
Btract (Continued)
structures, constructing drains and fencing, and placing fill material onsite. A 1990
ROD addressed onsite and offsite soil and ground water. This ROD amends the remedy for
soil and replaces in-situ vitrification with onsite disposal and capping. The ground
water remedy will not change and will be implemented as called for in the 1990 ROD. The
primary contaminant of concern affecting the soil is the metal arsenic.
The amended remedial action for this site includes excavating all offsite soil
contaminated with arsenic above 30 mg/1; placing the soil back on the site; construction
of a multi-layer cap and implementing institutional controls to restrict future land use.
The estimated present worth cost for this amended remedial action is $5,803,300. O&M
costs were provided in the 1990 ROD.
PERFORMANCE STANDARDS OR GOALS: The cap will comply with RCRA requirements for landfill
closure. The chemical-specific goal for soil is 30 mg/1. Onsite surface water must meet
the CWA ambient water quality criteria for arsenic 0.0175 ug/1. The ground water
remediation goal at the site is 0.05 mg/1.
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:9C' N Asard S Da:.a$ ~e*as "520" >e:r:"e I'--969-697' :;x 214-969-7616
July 21,1992
Mava Elliott, Work Assignment Manager
U.S. EPA Region 6
1445 Ross Avenue, Suite 1000
Dallas, TX 75202-2733
RE: TES X Work Assignment No. C06025
Crystal Chemical Amended Record of Decision
Dear Ms. Elliott:
As you requested during our 07/16/92 conversation, I have enclosed the Crystal
Chemical Site Amended Record of Decision (ROD) in which you expressed an
interest.
If you need any further information, please call me with your request.
Sincerely,
Coley Cnaudoin
Research Assistant
Enclosure
cc: John Shriwise, DPRA, w/o Enclosure
File/3732.625
2" Researc' D- .e -~. 5:' 71' Ma-iEata*" Kansas 655C2 Teieonorie9';:-5J9-35£: FA; 915-539-535; Teiex 704314
Oineronces Wasnngtc" DC S; Pat- Cnicagc Denser Oalias Kansas City
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STATUTORY PREFERENCE FOR TREATMENT AS A
PRINCIPAL ELEMENT IS NOT MET
AND FIVE-YEAR SITE REVIEW IS REQUIRED
SITE NAME AND LOCATION
Crystal Chemical Company
3502 Rogerdale Road
Houston, Texas
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected remedial action for the Crystal Chemical
Company site, Houston, Texas, which was chosen in accordance with Comprehensive
Environmental Response, Compensation, and Liability Act, as amended by Superfund
Amendments and Reauthorization Act, 42 U.S.C. Section 9601, etseq., and to the extent
practicable the National Oil and Hazardous Substances Pollution Contingency Plan, 40
CFR Part 300. This decision is based on the administrative record for this site.
The State of Texas was given an opportunity to comment on the selected remedy,
however, did not provide any comments.
ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances from this site, if not addressed
by implementing the response action selected in this Amended Record of Decision, may
present an imminent and substantial endangerment to public health, welfare, or the
environment.
DESCRIPTION OF THE REMEDY
This Amended Record of Decision addresses the contaminated soils on and off-site. The
ground water remedy selected in the 1990 Record of Decision will be implemented as
it was described in that document The remedy for the soil contamination addresses the
principal threats at the site by eliminating potential exposure via ingestion, inhalation .or
direct contact with contaminants and by reducing the potential for the soil to act as a
continued source for surface water and ground water contamination.
The major components of the selected remedy include:
Excavate arsenic-contaminated soil above 30 parts per million (ppm) from
off-site and place it on the site.
Install a multi-layer cap over the entire site.
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DECLARATION
The selected remedy is protective of public health and welfare and the environment,
complies with Federal and State requirements that are legally applicable or relevant and
appropriate to the remedial action, and is cost-effective. This remedy utilizes permanent
solutions and alternative treatment technologies to the maximum extent practicable for
this site. However, because treatment of the principal threat of the site was not found
to be practicable, this remedy does not satisfy the statutory preference for treatment as
a principal element of the remedy.
Because this remedy will result in hazardous substances remaining on site, a review will
be conducted within five years after commencement of remedial action to ensure that
the remedy continues to provide adequate protection of public health and welfare and
the environment.
JUN 1 6 1392
B. U. Wynne
Regional Administrator
Region VI
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CRYSTAL CHEMICAL COMPANY SITE
RECORD OF DECISION
CONCURRENCE
JUNE 1992
S$n Hitt Section Chief & - 3
Superfund Enforcement Texas Section (6H-ET)
Sam Becker, Chi
Superfund Enforcement Branch (6H-E)
Michael C. Barr
Assistant Regional Counsel (6C-WT)
Pam Phillipte1'-'7
Assistant Regional/Counsel (6C-WT)
Assistant Regidnal Counsel (6C-W)
Geo/gfe 'Alexander
Regional Counsel (6C)
Allyn M.Davis, Direc
Hazardous Waste Managment Division (6H)
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CRYSTAL CHEMICAL COMPANY SITE
AMENDED RECORD OF DECISION
TABLE OF CONTENTS
I. SITE NAME AND LOCATION 1
II. SITE HISTORY AND BACKGROUND INFORMATION 1
III. HIGHLIGHTS OF COMMUNITY PARTICIPATION 3
IV. SUMMARY OF .SITE RISKS 4
V. SCOPE AND ROLE OF AMENDED RESPONSE ACTION 7
VI. DESCRIPTION OF ALTERNATIVES , . 7
VII. SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES 15
VIII. SELECTED REMEDY 21
IX. STATUTORY DETERMINATIONS 22
X. DOCUMENTATION OF SIGNIFICANT CHANGES 25
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DECISION SUMMARY
FOR THE
CRYSTAL CHEMICAL SITE
HOUSTON, TEXAS
I. SITE NAME AND LOCATION
The Crystal Chemical Company site ("Crystal Chemical site" or the site") is located at
3502 Rogerdale Road, in southwestern Houston, Harris County, Texas. The company
operated on approximately 6.8 acres. The acreage is bounded on the west by the
Harris County Rood Control Channel and lies immediately south of Westpark Drive. The
area! extent of contamination covers approximately 24.4 acres. (All further discussions
referring to the "onsite contamination" refer to the 6.8 acres on which the Crystal
Chemical Company operated, and discussions of "offsite contamination11 refer to the
estimated areal extent of contamination off of the site that covers approximately 17.6
acres.) The site is located east of the area of Harris County known as Alief (see Figure
1). While the Crystal Chemical Company was operating, four evaporation ponds,
several structures, and many storage tanks existed on the site (see Rgure 2). The site
is now fenced, and all above ground structures have been removed. The site has also
been capped and graded in order to promote drainage (see Rgure 3). The land
immediately surrounding the site is vacant, commercial, and industrial property. An
estimated 20,000 people live within a one-mile radius of the site. Approximately 20
water wells are located within a one-mile radius of the Crystal Chemical site. These
include public drinking water wells, and industrial, irrigation, and observation wells.
The Harris County Rood Control Channel bounds the Crystal Chemical site on the west.
Surface waters that enter the flood control channel flow south and are discharged into
the Brays Bayou, approximately one mile south of the site. Brays Bayou eventually
drains into the Houston Ship Channel, which enters Scott Bay and eventually Galveston
Bay. There is no designated Texas significant habitat, agricultural land, or
historic/landmark site directly or potentially effected. A Preliminary Natural Resource
Survey was conducted by the National Oceanic and Atmospheric Administration
("NOAA") in February 1989. To date, NOAA has not indicated whether there is direct
impact to NOAA resources. Additionally, there are no endangered species or critical
habitats within close proximity of the site.
II. SITE HISTORY AND BACKGROUND INFORMATION
Crystal Chemical Company produced arsenical, phenolic and amine-based herbicides
from 1968 to 1981. Operation and maintenance problems at the Crystal Chemical
facility during the late 1970s resulted in several violations of the environmental standards
of the Texas Department of Water Resources ("TDWR"), now the Texas Water
1
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3 QC
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PROPERTY LINE
40
•01
FIGURE 2
HISTORIC SITE MAP
SOURCE: D'APPOLONIA/ERT/BFI
SITE INVESTIGATION
JANUARY, 1984
METCALF &
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POOR QUALITY
ORIGINAL
n
w
i a
t I C
1
i S
I I
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I
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Commission ("TWO"). The primary problem was repeated flooding of the site which
carried arsenic-contaminated wastewater offsite. In 1978 the Crystal Chemical Company
applied to the State of Texas for an onsite deep well injection permit to dispose of the
facility's wastewaters which were being stored in the four onsite wastewater evaporation
ponds. The permit was denied.
In September 1981, Crystal Chemical filed for bankruptcy and abandoned the site,
leaving approximately 99,000 gallons of arsenic trioxide in a storage tank and
approximately 600,000 gallons of wastewater in the evaporation ponds. Arsenic trioxide
is a substance used in the manufacturing of weed killers, enamels, and pesticides. It
may be highly toxic and a potential cause of cancer.
The United States Environmental Protection Agency ("EPA") initiated an Emergency
Removal Action to stabilize the site in September 1981, and the action was completed
in February 1983. During the first phase of the EPA emergency cleanup, the wastewater
was removed from the ponds and disposed of at an offsite commercial waste disposal
facility. The top foot of soil was removed, mixed with lime, then deposited back into the
wastewater ponds. A temporary cap, which included a plastic cover topped by a layer
of clay, was placed over the area to limit the infiltration of water into contaminated soil.
The arsenic trioxide was sold, and the buildings and process equipment were
disassembled, decontaminated and sold, essentially leaving the site vacant. The only
remaining structures onsite are two concrete slabs. Subsequently, EPA has taken
further measures to control surface runoff and site access, and to enhance the integrity
of the temporary cap. Steps taken by EPA in 1983 and 1988 included construction of
drains, fencing, and placement of additional fill onsite.
In 1983, the Crystal Chemical property was added to the National Priorities List ("NPL"),
pursuant to Section 105 of the Comprehensive Environmental Response,
Compensation, and Liability Act ("CERCLA"), 42 U.S.C. Section 9605, as amended,
qualifying the site for investigation and remediation under CERCLA, more commonly
known as Superfund.
In June 1990, EPA originally proposed a plan for the arsenic-contaminated soils and for
the contaminated ground water, and the Record of Decision ("ROD") documenting the
remedy selection was issued on September 27, 1990. The ground water remedy that
was selected in the 1990 ROD consisted of extraction, treatment, and discharge to a
Publicly Owned Treatment Works ("POTW), to surface water, or reinjection. The soils
remedy proposed and selected by EPA in 1990 included excavating offsite soils
contaminated with arsenic greater than 30 parts per million ("ppm"), treating all the soils
contaminated with arsenic greater than 300 ppm with a process called In-Situ
Vitrification ("ISV"), and capping the entire site after the soils treatment had been
completed. The ISV technology is a process which uses electricity to generate heat
which will melt the contaminated soil. The process destroys many contaminants when
the soil is heated and permanently bonds other contaminants into the glass-like material
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as it cools. The glass-like material is expected to remain stable for thousands of years.
Soils from the Crystal Chemical site were actually treated using this process, and tests
conducted on the glass-like material have shown that only a very small amount of
arsenic is able to leach.
However, EPA was notified in July 1991 by the only vendor of the ISV technology that
the technology would be unavailable for an undetermined period of time because of the
need to do additional analytical and experimental work on the technology. After
evaluating its options, EPA decided that it is in the best interest of public health, welfare,
or the environment to proceed with the selection of another remedy for soil
contamination.
The remedial alternatives considered for the Crystal Chemical site are described in detail
in the Supplemental Feasibility Study ("SFS") report. This amended decision document
presents the selected remedial action for the Crystal Chemical site, Houston, Texas,
-chosen in accordance with CERLCA, as amended by the Superfund Amendments and
Reauthorization Act of 1986 ("SARA") and, to the extent practicable, the National Oil and
Hazardous Substances Pollution Contingency Plan ("NCP"), 40 CFR Part 300. The
decision for this site is based on the administrative record. An index for the
administrative record is included as an attachment to this document.
III. HIGHLIGHTS OF COMMUNITY PARTICIPATION
The Amended Proposed Plan for the Crystal Chemical site was released to the public
in early February 1992. This document as well as all other site related documents are
available to the public at both the administrative record and the information repository
locations. A summary of the Amended Proposed Plan and the notice of the availability
of these documents and the administrative record was published in the Houston Post
on February 12, 1992. The public comment period began on February 24, 1992, and
ended March 24, 1992. An informal Open House was held in the area near the site on
February 20,1992. The Public Meeting was held on March 19,1992, at the Westchase
Hilton and Tower in Houston, Texas. The purpose of this meeting was to discuss all the
available alternatives and EPA's preferred alternative for the soil contamination at the
Crystal Chemical site. A response to the comments received during this period
including those expressed verbally at the public meeting is included in the
Responsiveness Summary, which is included as a part of this Amended ROD. This
decision document presents the selected remedial action for the soil contamination for
the Crystal Chemical site, Houston, Texas, chosen in accordance with CERCLA, as
amended by SARA, and, to the extent practicable, the NCP, 40 CFR Part 300. The
decision for this site is based on the administrative record. An index for the
administrative record is included as an attachment to this document.
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IV. SUMMARY OF SITE RISKS
The following discusssion is an excerpt from the Summary of Site Risk section
contained in the 1990 ROD. It is being included in this Amended ROD in order to
provide for continuity and clarity between the two documents.
During the SFS, a Health Assessment was prepared for EPA by the Agency for Toxic
Substances and Disease Registry ("ATSDR"). This report reviewed the potential risks
to human health posed by the Crystal Chemical site in regards to contaminant sources
and potential contacts to the population. The ATSDR determined that arsenic was the
only contaminant of concern with respect to public health. Arsenic ranks twentieth
(20th) in abundance among the natural elements in the Earth's crust and, therefore, is
found naturally occurring in rocks and soils. It is widely used in herbicides and is found
in both organic as well as inorganic forms on the Crystal Chemical site. The arsenic
found on the Crystal Chemical site exhibits characteristics of a substance that is
regulated under the Resource Conservation and Recovery Act ("RCRA"), as amended,
42 U.S.C. Section 6901, et seq., and a specific type of arsenic (i.e., K031 - by-product
salts generated in the production of monosodium methylarsenate ("MSMA") and
cacodylic acid) that is listed and regulated under RCRA was produced on the site.
ATSDR determined that the areas of concern where potential exposure to the arsenic
contamination was most likely to occur would be surface soil and surface water. The
susceptible populations were identified as children who may play in the immediate
vicinity of the site and workers who may be involved in maintenance and remediation
activities at the site. The identified exposure pathways include direct skin contact,
ingestion of contaminated ground water, surface water and surface soil, and inhalation
of contaminated airborne dusts.
Also, during the SFS, an analysis was conducted to estimate the health or
environmental problems that could result if no action were taken on the soil
contamination at the Crystal Chemical site. This analysis is commonly referred to as an
endangerment assessment. The primary purpose of the endangerment assessment is
-to evaluate potential health effects that could result from direct exposure to the
contaminant as a result of contaminated soil, surface water or airborne dust coming in
contact with an individual through direct contact with the skin, ingestion (eating or
drinking), or inhalation,- and to determine appropriate remediation levels of the
contaminant of concern. Irrthis case, arsenic in its most toxic form (trivalent, inorganic
arsenic) is the contaminant of concern. Although phenol has been found onsite, the
ATSDR Health Assessment determined that phenolic compounds did not present a
potential health problem to area residents and workers in the area due to the low levels
that were detected at the site. Although phenol has been found onsite at a maximum
concentration of 157 ppm, the endangerment assessment did not evaluate risk because
concentrations of this compound were well below any health-based levels of concern.
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With respect to potential health effects, the results of the endangerment assessment
supported the ATSDR Health Assessment and identified the following five specific
potential ways in which individuals could become exposed at the site:
ingestion of or direct contact with soil and sediments,
ingestion of or direct contact with surface water,
ingestion of shallow ground water,
inhalation of wind dispersed dust, or
ingestion of contaminated fish.
The contaminated soil was determined to be a principal threat at the site because of
direct contact, ingestion, and inhalation risks and because of the soil's impact on
ground water. The remedial objectives for the soil are to eliminate potential exposure
via ingestion, inhalation or direct contact with contaminants and by reducing the
potential for the soil to act as a continued source for surface water and ground water
contamination.
The contaminated shallow ground water was also determined to be a principal problem
at the site because of the potential exposure of the public to the site contaminants and
because of the threat of migration of contaminants to deeper zones of ground water.
The deeper ground water zones are used for industrial, irrigation, and drinking water
purposes. The remedial objective is to reduce the amount of contamination to human
health-based standards in order to eliminate or minimize the risks associated with the
contaminated shallow ground water.
Arsenic was determined by ATSDR to be the contaminant of concern at the Crystal
Chemical site, therefore, all remediation goals are set for arsenic. The only other
'contaminant found at the site which may be of concern was phenol. Remediation levels
assuming chronic daily exposure in order to protect against noncarcinogenic effects
were calculated for the phenolic compounds. The remediation levels were calculated
to be 420,000 ppm for an aduit and 50,000 ppm for a child. The remediation levels for
phenolics have no significant.effect on the volumes of soil or ground water requiring
remediation at the site, and because these levels are relatively high compared to
phenolic levels found at the site (approximately 160 ppm), the remediation levels for the
phenols are not discussed in the review and evaluation of remedial technologies.
The selection of an appropriate remediation level for arsenic was based primarily on an
evaluation of the potential health effects caused by human exposure to the contaminant,
assuming that the future land use will be residential and commercial/industrial. The
reasoning behind designating the future land use as possibly residential is that the City
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of Houston does not, at this time, have zoning ordinances, therefore, EPA takes a
conservative approach and calculates risk so that all potential scenarios are taken into
consideration.
To a lesser extent remediation levels for arsenic were based on the naturally occurring
background conditions of arsenic in soils. Arsenic is a naturally occurring metallic
constituent of soils, derived from the rock or parent materials, from which the soil was
formed. Background concentrations of metals in soil may vary from region to region.
For example, the United States Geological Survey (1975) reports that the mean and
range of background arsenic concentrations in western soils is 6.1 ppm and 0.2-97
ppm, respectively.
A limited number of soil samples collected from offsite areas within two miles of the
Crystal Chemical site found background arsenic concentrations to be less than 1.6 ppm.
Soil sampling at the site found arsenic concentrations on the order of several hundred
to several thousand ppm. As determined in the endangerment assessment, leaving this
contamination on site without treatment would result in a one in ten thousand (10"4) risk
of cancer over the lifetime of individuals who may come in contact with this
contamination. This estimate was developed by taking into account various
conservative assumptions about the likelihood of a person being exposed to the
contaminated soil, and in consideration of the toxicologicai effects of arsenic exposure.
The national risk of getting some form of cancer over a 70 year life span is very high,
estimated at one chance in five or 0.2. The one in five probability is the baseline
situation or "natural incidence" of cancer. A one in ten thousand (10"4) risk is an
increment above the baseline risk (an increase from 0.200 to 0.201). EPA policy calls
for an evaluation of remediation levels that range from a cancer risk of one in ten
thousand to one in one million (10"* to 10"6), using one in one million as a point of
departure.
Utilizing conclusions made concerning the public to be protected and the amount and
duration of exposure, the endangerment assessment calculated health standards for
arsenic in surface soil and sediment. These goals call for the removal of offsite soils to
a concentration of 30 ppm for arsenic, which represents a one in one hundred thousand
(10'5) cancer risk level. * Since the average background concentration of arsenic in
western soils (6.1 ppm) exists at a level in excess of EPA's standard point of departure
(one in one million cancer risk - at a 3 ppm concentration of arsenic), 30 ppm was
determined to represent a safe health-based action level. These soils will be placed
back on to the'Crystal Chemical site, and a multi-layer cap will be constructed over the
entire site. Once the soil remedy is complete, the resulting cancer risk will be reduced
to less than one in one million (at or near the original background conditions).
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V. SCOPE AND ROLE OF AMENDED RESPONSE ACTION
The studies undertaken at the Crystal Chemical site have identified two principal threats
(i.e., contaminated soil and shallow ground water), and the remedies to eliminate or
minimize these threats that are included in the 1990 ROD and this Amended ROD and
are addressed as one operable unit.
The contaminated soil was determined to be a principal threat at the site because of
direct contact, ingestion, and inhalation risks and because of the soil's impact on
ground water. The remedial objectives for the soil are to eliminate potential exposure
via ingestion, inhalation or direct contact with contaminants and by reducing the
potential for the soil to act as a continued source for surface water and ground water
contamination.
The contaminated shallow ground water was also determined to be a principal problem
at the site because of the potential exposure of the public to the site contaminants and
because of the threat of migration of contaminants to deeper zones of ground water.
The deeper ground water zones are used for industrial, irrigation, and drinking water
purposes. The remedial objective is to reduce the amount of contamination to human
health-based standards in order to eliminate or minimize the risks associated with the
contaminated shallow ground water.
The remedy selected in the 1990 ROD for the contaminated ground water will not
change and will be implemented as it is called for in the 1990 ROD. However, because
of the unavailablity of the treatment technology selected in the 1990 ROD for the
arsenic-contaminated soils, this Amended ROD addresses the selection of a new
remedy to address the arsenic-contaminated soils at the Crystal Chemical site. The risk
range selected in the 1990 ROD for the contaminated soils will remain the same, i.e.,
one in one million excess lifetime cancer risk of 3 ppm to one in ten thousand excess
lifetime cancer risk of 300 ppm (1 x 10"6 to 1 x 10"4). Furthermore, the remediation goals
for soils will fundamentally remain the same. Therefore, the remediation goal for
'removal of offsite soils is 30 ppm, which represents a one in one hundred thousand (1
x 10"*) cancer risk level.
VI. DESCRIPTION OF ALTERNATIVES -
The alternatives for the soil remediation are the following:
Alternative A-1: Excavation and Offsite Disposal
•K«*>K-:wK..vKv;*Kv^^^^
Alternative A-3: Solidification/Stabilization
Alternative A-4: Soil Washing
Alternative A-5: Part'aJ IrvSftu Vtnfication ajTd C^pir^ U^VAIWB!^
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Alternative A-6: Partial Solidification/Stabilization and Capping
Alternative A-7: Partial Soil Washing and Capping
Alternative A-8: Capping
Alternative A-9: No Action
Alternative A-10: Umited Action
Common Elements. Except for the "No Action" and "Limited Action" alternatives, all of
the alternatives that were considered for the site included a number of common
elements. Each of the alternatives, with the exception of Alternative A-1, call for long-
term monitoring activities that will be conducted to ensure that the remedy remains
effective and continues to protect public health and the environment. In addition,
restrictions will be placed on the site to prohibit certain activities, such as soil removal
or construction of buildings at the site, and site access will be restricted.
All of the alternatives involve the removal of offsite soil and sediments with arsenic
contamination greater than 30 ppm, EPA's offsite remediation level, and these offsite
areas will be backfilled to previously existing grades. Alternative A-1 proposes to
dispose of all contaminated soils at an offsite landfill; all other alternatives involve onsite
placement of the offsite soil and sediments. Two concrete slabs remain on the site.
Soil Alternatives A-1 through A-4 call for removing the slabs and disposing of them off
site. Alternatives A-6 through A-8 call for removing the slabs, breaking them into smaller
pieces, and placing them under the multi-layer cap that is to be constructed over the
site. All costs and time required to implement all of the alternatives are estimates. The
cost estimates were originally developed in 1989 based on information from the
treatment technology vendors. Because of the rate of inflation since 1989, the originial
estimates have been increased by 3.5%.
When remediating a site, there are applicable or relevant and appropriate requirements
("ARARs) that the remedy(s) must meet in order to be in compliance with Federal and
State laws. Given that the arsenic found on the site exhibits characteristics of a
substance that is regulated under RCRA, 40 CFR Subpart C, and that a type of arsenic
.(i.e., K031 - by-product salts generated in the production of MSMA and cacodylic acid)
that is specifically listed and regulated under RCRA, 4O CFR Subpart D, was produced
on the site, certain ARARs apply. If a waste leaches above 5.0 ppm of arsenic when
analyzed using the Toxicity Characteristic Leaching Procedure ("TCLP"), 40 CFR 261.25,
it is considered a hazardous waste and is regulated under RCRA. Furthermore, if a
RCRA regulated waste is treated, additional ARARs apply.
On June 1,1990 a regulation identifying vitrification as the best demonstrated available
treatment technology ("BOAT) for arsenic as a RCRA characteristic waste as well as a
RCRA listed waste was published (55 Fed. Reg. 106 at 22556 to 22561). The effective
date of this regulation was August 8, 1990. Associated with the BOAT is a
concentration-based treatment standard of 5.6 ppm for K031 nonwastewaters, and the
BDAT concentration-based treatment standard for arsenic as a characteristic (D004)
8
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nonwastewater is 5.0 ppm. When the soils treatment and replacement triggers
placement (Soils Alternatives A-3, A-4, A-6, and A-7) or when offsite disposal of
contaminated soil is involved which, too, triggers placement (Soil Alternative A-1) under
RCRA's Land Disposal Restrictions ("LDRs"), 40 CFR 268, the 5.6 ppm treatment
standard for nonwastewaters is required per 40 CFR 268.9.
Soil Alternative A-1:
EXCAVATION AND OFFSITE DISPOSAL
This alternative calls for excavating all onsite and ail offsite soils and sediments with
arsenic contamination greater than 30 ppm. The estimated volume of soils
contaminated with arsenic greater than 30 ppm is 156,000 cubic yards. These
excavated soils would then be transported offsite for disposal in a landfill that is allowed
to accept arsenic-contaminated soils. All excavated areas would be back-filled with soil
to previously existing grades and the area would be revegetated. The total cost of this
alternative is approximately $84,266,100, and the estimated time required to implement
this alternative would be 2.5 years.
This alternative calls for the removal of the contaminated soils from the site and
disposing of them elsewhere. The offsite and onsite soils with arsenic contamination
greater than 30 parts per million would be excavated, and transported off site and
disposed in a landfill that is allowed to accept arsenic-contaminated soils. This
alternative reduces site risk by removing soil that is contaminated at levels which may
pose health or environmental risks. However, this alternative is not favored by EPA
because CERCLA discourages offsite transportation and disposal of contaminated
materials.
Soil Alternative A-2:
Soil Alternative A-3:
SOLIDIFICATION/STABILIZATION
Solidification is a process which changes a liquid or a sludge into a solid thus changing
its physical state and characteristics. Stabilization is a process which mixes chemically
binding materials with contaminated soil to reduce the ability of the contaminants to
leach out of the soil into the surrounding environment A treatment rate of 1,000 cubic
yards per day is possible when using this treatment technology. For this alternative, all
offsite and onsite arsenic-contaminated soils and sediments would be excavated and
then treated using the solidification/stabilization process. The site would be backfilled
with the treated soil. The volume of offsite soils requiring excavation is estimated to be
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55,000 cubic yards, and the total volume of soils requiring treatment with this alternative
is estimated to be 156,000 cubic yards. The total cost of this alternative is
approximately $32,768,300 and it would take approximately 3 years to implement this
remedy.
Solidification/stabilization has been used successfully many times on hazardous waste
sites and conforms with the CERCLA preference for remedies that involve the treatment
of contaminants. However, tests conducted on the arsenic-contaminated soil from the
Crystal Chemical site treated using the solidification/stabilization process have shown
that a high concentration of the arsenic (78 to 288 parts per million) continues to leach
out of the soil after the treatment has been completed, therefore, the mobility of the
arsenic has only been slightly reduced (See Table 1). The Superfund Program uses as
a guideline for effective treatment the range of 90 to 99 percent reduction in the
concentration or mobility of the contaminant of concern. Solidification/stabilization was
able to only reduce the amount of teachable arsenic by 68% and even this reduction is
not consistent, therefore, EPA does not consider this technology to be an effective
treatment technology for the Crystal Chemical site. Furthermore, there is no indication
that solidification/stabilization technology reduces the toxicity of the contaminant.
In addition, this technology will significantly increase the volume (a minimum of 10% to
30%) of the contaminated soil that will need to be put back on to the site. Furthermore,
the soil volume increase that occurs when the soils in this area are excavated is
documented to be approximately 40%. The naturally occurring volume increase of 40%
coupled with the 10% to 30% increase caused by the treatment would significantly
increase the volume of treated soil that requiring permanent storage on the site, creating
an unacceptably large soil pile, possibly as high as 19 feet Therefore, using this
technology will only serve to create a larger volume of waste that would need to be
placed on the site and a larger volume of waste that would continue to leach arsenic
with little or no reduction in the risks posed by the site. In conclusion, the
ineffectiveness of this treatment technology coupled with the drawbacks (volume
increase) of using this treatment technology far outweigh the Superfund preference to
use treatment when available. For these reasons EPA does not favor this alternative.
Soil Alternative A-4:
SOIL WASHING
Soil Washing is a process which removes contaminants from soil by mixing the
excavated contaminated soils with a liquid. During the mixing process, the
contaminants are washed from the soil. The liquid containing the contaminants is then
drained from the soil, the contaminant is removed from the liquid, and the contaminants
are disposed in an offsite landfill which is allowed to accept arsenic contamination. The
soil processing rate for this technology is approximately 200 cubic yards per day. This
alternative calls for the excavation of all offsite and onsite arsenic-contaminated soils and
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sediments. The volume of soils estimated to require treatment with this alternative is
156,000 cubic yards. After the washing process, the site would be backfilled with the
washed soil. This alternative would take approximately 6 years to implement and would
cost an estimated $134,719,000.
This alternative does use treatment, and tests conducted on contaminated soils from the
Crystal Chemical site using the soil washing technology indicate that the treatment has
been able to remove 90% of the teachable arsenic (See Table 1). However, the
technology cannot be considered appropriate for the Crystal Chemical site because the
arsenic is only concentrated at the completion of the treatment process. This
concentration of arsenic will require onsite or offsite land disposal since arsenic is an
element and cannot be destroyed. Because state and Federal environmental
regulations restrict certain land disposal practices, the disposal will be difficult or further
treatment of the arsenic concentration will be required before disposal can occur. In
conclusion, the use of this treatment technology will provide no overall benefit and will
provide little or no reduction in the risks posed by the site. For these reasons EPA does
not favor this alternative.
Soil Alternative A-5:
UNAVAILABLE
.- v •*•* .v. *.i".s'". •,/•.-..•. v
Soil Alternative A-6:
PARTIAL SOLIDIFICATION/STABILIZATION AND CAPPING
This alternative is similar to Soil Alternative A-3, however, only those soils with arsenic
contamination greater than 300 ppm would be treated using the
solidification/stabilization process. The volume of soils requiring treatment is estimated
to be 16,500 cubic yards. A multi-layer cap would be constructed over the entire site
after the soils had been treated. The cap acts as a barrier that restricts the flow of water
. through the soils which are not subjected to water table conditions, prevents the release
of soil and residual contaminants into the air, and prevents direct contact with the
treated soil and the contaminants. This alternative would cost approximately $9,236,800
and would take an estimated 2.5 years to implement.
This alternative would somewhat decrease site risk by slightly reducing the mobility of
contaminants present in the soil, however, there would be no reduction in the toxicity
or volume of contaminants. Furthermore, this technology increases the volume of
contaminated soil by a minimum of 10% to 30%. The soil volume increase that occurs
when the soils in this area are excavated is documented to be approximately 40%. This
naturally occurring volume increase of 40% coupled with the 10% to 30% increase will
significantly increase the volume of treated soil that will require permanent storage on
the site. Therefore, this alternative may create an unacceptably large soil stockpile.
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This alternative also requires that a multi-layer cap be constructed over the treated soils,
therefore, the stockpile coupled with the height of the cap constructed (9 to 15 feet
high) will be environmentally and aesthetically unacceptable. For these reasons and
other reasons as in the discussion of Soil Alternative A-3, this alternative is ineffective,
impracticable, and has many drawbacks, therefore, it is not favored by EPA.
Alternative A-7:
PARTIAL SOIL WASHING AND CAPPING
This alternative is similar to Soil Alternative A-4, however, only those soils with arsenic
contamination greater than 300 ppm would be treated using the soil washing process.
The volume estimated to require treatment is 16,500 yards. A multi-layer cap consisting
of clay, plastic, sand, topsoil, and vegetation would be constructed over the entire site
after the soils had been treated. The cap acts as a barrier that restricts the flow water
through soils which are not subjected to water table conditions, prevents the release of
soil and residual contaminants into the air, and prevents direct contact with the treated
soil and the contaminants. This alternative would cost approximately $21,618,400 and
would take an estimated 3.75 years to implement.
As with Soil Alternative A-4, there are drawbacks to this alternative, the more important
being the need to dispose the concentrated arsenic that will result from the treatment.
Ultimately, this concentrated arsenic may have to be disposed on the site because of
state and Federal environmental regulations that restrict certain land disposal practices.
If offsite disposal is desired, a pre-treatment step to reduce the teachability of the
arsenic will be required before an offsite facility will accept the arsenic contamination.
For these reasons as well as the reasons associated with alternative A-4, EPA does not
favor this alternative.
Alternative A-8:
CAPPING
The capping alternative calls for all soils and sediments from offsite that have arsenic
contamination greater than 30 ppm to be brought back on to the site. Then a multi-
layer cap would be constructed over the entire site. The cap acts as a barrier that
restricts the flow of water through the soils, prevents the release of soil contaminants
into the air, and prevents direct contact with contaminants. Although a cap was
constructed over the site in 1983 during an EPA Emergency Removal Action and this
cap has eliminated direct contact with the contaminant and has minimized or eliminated
infiltration, this cap was constructed to be a temporary barrier. If a cap is to be a
permanent barrier, a more substantial cap design must be constructed. This alternative
would take approximately 2.25 years to implement and would cost approximately
$5,803,300.
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Although no treatment of the soils will be done before the site is capped, the multi-layer
cap will ultimately aid in reducing the amount of ground water contamination by
eliminating the infiltration of water through the arsenic-contaminated soil. Additionally,
through the ground water extraction process, the arsenic contamination within and
below the ground water table will be eliminated. Therefore, the mobility of the
contaminants in the soil will be somewhat reduced if a permanent cap were constructed
over the site, however, neither the volume of the contaminated soils nor the toxicity of
the contaminants would be reduced.
Treatment of the source of contamination is always preferable to no treatment, however,
in this case the treatment of the arsenic contaminated soils at the Crystal Chemical site
may cause more environmental problems due to an ineffective and impracticable
treatment (i.e., solidification/stabilization or soil washing) technology than it would solve.
This alternative provides for the protection of public health and significantly reduces the
risks posed by the site. Therefore, this is EPA's preferred alternative.
Alternative A-9:
NO ACTION
The Superfund program requires that a no action alternative be considered at every site
as a basis of comparison when evaluating other alternatives. No action assumes that
nothing would be done to restrict site access, monitor offsite contaminated soil, or to
maintain the existing temporary cap. Therefore, there would be no costs associated
with this alternative. This alternative is not favored by EPA because it would not
decrease the toxicity, mobility, or volume of contaminants or reduce public health or
environmental risks.
Alternative A-10:
LIMITED ACTION
This alternative involves site access and land use restrictions that include prohibiting
activities such as soil removal or any type of commercial or residential activity on the
site. The costs associated with this alternative are approximately $107,100, and the
restrictions would be enforced in perpetuity.
This alternative would somewhat reduce risks to public health and the environment by
restricting site use and access and by maintaining the existing cap. However, the cap
that exists on the site was contructed in 1983 during one of EPA's emergency removal
actions and was not intended to be a permanent barrier to prevent migration of arsenic
from the site or migration of surface waters through the contaminated soils. Although
the temporary cap has served its purpose well, this alternative does not provide long-
term protection to public health or the environment, therefore, EPA does not favor it.
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VII. SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
The nine (9) criteria used in evaluating all of the alternatives identified in the SFS are as
follows:
Overall protection of human health and the environment,
Compliance with applicable or relevant and appropriate requirements,
Long-term effectiveness and permanence,
Reduction of toxicity, mobility, or volume through treatment,
Short-term effectiveness,
Implementability,
Cost,
State/support agency acceptance, and
Community acceptance.
Explanation of Evaluation Criteria
Overall Protection of Human Health and Environment addresses whether or not
a remedy provides adequate protection and describes how risks posed through
each pathway are eliminated, reduced, or controlled through treatment,
engineering controls or institutional controls.
Compliance with ARARs addresses whether or not a remedy will meet all of the
applicable or relevant and appropriate requirements of other Federal and State
environmental statutes and/or provide grounds for invoking a waiver.
Long-term effectiveness and permanence refers to the magnitude of residual risk
and the ability of a remedy to maintain reliable protection of human health and
the environment over time once cleanup goals have been met.
Reduction of toxicity, mobility, or volume through'treatment is the anticipated
performance of the treatment technologies that may be employed in a remedy.
Short-term effectiveness refers to the speed with which the remedy achieves
protection, as well as the remedy's potential to create adverse impact on human
health and the environment that may result during the construction and
implementation period.
Implementability is the technical and administrative feasibility of a remedy,
including the availability of materials and services needed to implement the
chosen solution.
Cost includes capital and operation and maintenance costs.
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State Acceptance indicates whether, based on its review of the RI/FS and
Proposed Plan, the State concurs with, opposes, or has no comment on the
preferred alternative.
Community Acceptance will be assessed in the Record of Decision following a
review of the public comments received on the RI/FS report and the Proposed
Plan.
Comparative Analysis:
Overall Protection. All of the alternatives, with the exception of the "no action11 and
"limited action" alternatives, may provide some protection of human health and the
environment by eliminating, reducing, or controlling risk through treatment, capping, or
deed and land use restrictions. The preferred alternative calls for capping all of the
arsenic-contaminated soils above acceptable health-based levels, which are soils
contaminated with arsenic above 30 parts per million. The cap itself acts as a barrier
that restricts the flow of water through the soils which are not subjected to water table
conditions, prevents the release of soil and residual contaminants into the air, and
prevents direct contact with the arsenic contamination. Because the ground water
extraction and treatment remedy selected in the 1990 ROD will be implemented, through
the extraction of the contaminated ground water, this source of arsenic contamination
will be eliminated. Additionally, the arsenic contaminated soils below the ground water
table will be treated during the implementation of the ground water remedy. The arsenic
contaminates adsorped to the soil particles within the ground water saturated zone will
be desorped during the pumping process and extracted for treatment. The desorption
and extraction of the arsenic will make less arsenic available thus eliminating the source
of arsenic contamination within the ground water saturated zone and preventing further
or continued release into the ground water.
Therefore, the remedial objectives achieved through the implementation of the preferred
soil alternative would be the elimination of the potential exposure via ingestion,
inhalation or direct contact with the contaminants. The remedial objectives achieved
through the implementation of the ground water remedy selected in the 1990 ROD will
be the elimination of the potential exposure via ingestion and direct contact with
contaminants and the elimination the potential for migration of contaminants to deeper
zones of ground water.
The Superfund Amendments and Reauthorization Act of 1986 ("SARA") places an
emphasis on the remedies which employ treatment that permanently and significantly
reduces the volume, toxicity or mobility of the hazardous substances, pollutants, and
contaminants over remedies that do not employ such treatment. The Superfund
program uses as a guideline for effective treatment the range of 90 to 99 percent
reduction in the concentration or mobility of the contaminant of concern. Therefore,
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EPA believes that treatment technologies that cannot achieve this level of performance
on a consistent basis are not sufficiently effective and generally will not be appropriate.
The solidification/stabilization treatment technology has not been able to achieve the 90
to 99 percent reduction in the concentration or mobility of teachable arsenic. In fact, the
technology has only been able to achieve a 68% reduction, and the percentage of
reduction has not been consistent. The soil washing treatment technology has been
able to achieve a 90% reduction in the concentration or mobility of teachable arsenic,
therefore, it can be considered an effective treatment technology. However, the
technology cannot be considered appropriate for the Crystal Chemical site because the
arsenic is only concentrated at the completion of the treatment process. This
concentration of arsenic will require onsrte or offsite land disposal since arsenic is an
element and cannot be destroyed. Therefore, through the conduct of the soil washing
treatment technology, no overall benefit has been achieved.
In conclusion, the treatment technologies available for the Crystal Chemical site are
either ineffective, do not afford a greater overall benefit, or do not afford a greater overall
reduction in risks posed by the site. Therefore, doing treatment for the sake of doing
treatment using the available technologies does not, in this case, appear to be
appropriate or beneficial.
Because 1he "no action* and "limited action* alternatives are not protective of human
health and the environment, they will not discussed any further.
Compliance with Applicable or Relevant and Appropriate Requirements (ARARs).
ARARs are the Federal and State requirements that a selected remedy must meet.
Given that the arsenic found on the site exhibits characteristics of a substance that is
regulated under RCRA, 40 CFR Subpart C, and that a type of arsenic (i.e., K031 - by-
product salts generated in the production of MSMA and cacodylic acid) that is
specifically listed and regulated under RCRA, 40 CFR Subpart D, was produced on the
.site, certain ARARs apply. If a waste leaches above 5.0 ppm of arsenic when analyzed
using TCLP, it is considered a hazardous waste and is regulated under RCRA
Furthermore, if a RCRA regulated waste is treated, additional ARARs apply.
On June 1,1990, a regulation identifying vitrification as the best demonstrated available
treatment technology ("BOAT") for arsenic as a RCRA characteristic waste as well as a
RCRA listed waste was published (55 Fed. Reg. 106 at 22556 to 22561). The effective
date of this regulation was August 8,1990. The concentration-based treatment standard
for K031 nonwastewaters is 5.6 ppm of arsenic, and the BOAT concentration-based
treatment standard for arsenic as a characteristic (D004) nonwastewater is 5.0 ppm.
When the soils treatment and replacement triggers placement (Soils Alternatives A-3,
A-4, A-6, and A-7) or when offsite disposal of contaminated soil is involved which, too,
triggers placement (Soil Alternative A-1) under RCRA's Land Disposal Restrictions
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("LDRs"), 40 CFR 268, the 5.6 ppm treatment standard for nonwastewaters is required
per 40 CFR 268.9. Although the vitrification technology alternatives investigated in the
SFS for the Crystal Chemical site are not available, the concentration-based treatment
standard associated with the BOAT remains the goal of any treatment technology. None
of the available treatment technologies have been able to achieve the required
concentration-based treatment standard. However, if one of the available treatment
technologies were practicable and were chosen as the selected remedy, a treatability
variance could be sought for this site.
Alternatives A-3, A-4, A-6, A-7, and A-8 must comply with two federal ARARs. The first
ARAR regards closure requirements for surface impoundments containing materials that
migrate out of soil above levels acceptable to EPA (i.e., TCLP level of 5.6 ppm for
arsenic). This ARAR is relevant and appropriate because the four evaporation ponds
that existed on the site during Crystal Chemical Company's operation were not closed
pursuant to the RCRA regulations during the EPA Emergency Removal Actions
'conducted on site. All of the alternatives that call for leaving arsenic-contaminated soils
on the site would have to meet this ARAR. Given that Alternatives A-6, A-7, and A-8 call
for construction of a multi-layer cap that could satisfy the requirements of this ARAR,
these alternatives would satisfy this ARAR. The second ARAR involves performance
standards for redeposited, treated soil regulated under the LDRs.
Solidification/stabilization and soil washing technologies trigger placement under the
LDRs thus must meet the LDR treatment standard or a variance to the standard if land
disposal is desired. Both of the treatment technologies associated with alternatives A-3,
A-4, A-6, and A-7 fail to treat the arsenic-contaminated soils to such a degree of success
that they are no longer regulated under RCRA or that they meet the performance
standard set for the contaminant, therefore, alternatives A-3, A-4, A-6, and A-7 would
fail to meet the LDR ARAR for the Crystal Chemical site. If the treatment technology
alternatives were practicable for the Crystal Chemical site, a variance to the LDR
standard would allow these alternatives to meet the LDR ARAR. However, because they
are impracticable, no variance will be sought, and the alternatives will fail to meet the
• LDR ARAR. Alternative A-T because it involves the offsite land disposal of arsenic-
contaminated soil would also fail to meet the LDR ARAR.
The selected remedy A-8 does not trigger placement under the LDRs, and the selected
remedy calling for construction of a multi-layer cap which will meet the ARARs for the
site. "
Long-term Effectiveness and Permanence. The preferred alternative involves
excavation of contaminated offsite soil and capping this soil with all the onsite soil
without performing any treatment. This capping alternative provides long-term
reductions in the amount of water that otherwise would pass through the contaminated
soil and would continue to carry the contaminants into surrounding soils and ground
water, and long-term reductions in the release of arsenic to surrounding soils and into
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the air. Although the direct contact risk would be eliminated with this alternative, the
cap must be maintained to be an effective barrier.
Alternative A-1 would eliminate the onsite and offsite risks of direct contact and the
continued release of contaminants into the air and ground water because the
contaminants would be removed from the site. However, with an offsite disposal
alternative the problem is just being shifted from one site to another, therefore,
Alternative A-1 does not provide a permanent resolution of the problem.
During bench scale treatability tests using actual contaminated soils from the site, the
solidification/stabilization technology (A-3 and A-6) failed to produce a significant
decrease in the amount of arsenic that is able to leach out of the treated soil or any
decrease in the contaminant's volume or toxicity, therefore, use of this treatment
technology does not provide long-term protection or a permanent solution to the arsenic
contamination. The soil washing technology (A-4 and A-7) has been able to
demonstrate that effective treatment can be achieved, however, the permanence of this
technology is in serious doubt because the arsenic is just concentrated, not destroyed.
Given that arsenic cannot be destroyed, the concentrated arsenic will require land.
disposal. Therefore, Alternative A-4 and A-7 do not provide a permanent solution to the
contamination problem.
The addition of a multi-layer cap to the treatment methods (A-6 and A-7) would provide
no added long-term protection from the arsenic nor permanent solution to the arsenic
contamination when using treatment technologies.
Reduction of Toxicity, Mobility, or Volume of the Contaminants Through Treatment
Two methods of treatment are proposed in this Amended Plan, alone and in conjunction
with capping. Alternatives A-3 and A-6 involve treatment by solidification/stabilization
which physically and/or chemically bonds contaminants. The site's treatability studies
.produced a treated mixture with reduced arsenic mobility (in one case, from 243 parts
per million before treatment to 78 parts per million after treatment), but the reduction by
only 68% of the teachable amount of arsenic is not considered acceptable to EPA.
Additionally, there is no evidence that the solidification/stabilization treatment process
reduces the toxicity of the contaminants or the volume of the contaminants.
Furthermore, this treatment process increases the contaminated soil volume after
treatment by approximately 10% to 30% at a minimum.
Alternatives A-4 and A-7 involve treatment by soil washing which concentrates the
contaminants into the wash liquid. The site's treatability study did produce a washed
soil with reduced arsenic (from 243 parts per million before treatment to 23 parts per
million after treatment). However, the arsenic is just concentrated after treatment, not
destroyed. Therefore, there is no reduction in the volume or toxicity of the contaminant.
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The preferred alternative, A-8, does not involve treatment therefore, there is no reduction
in the toxicity, mobility or volume through the use of treatment.
Short-term Effectiveness. The construction and/or implementation of the treatment
technologies for most of the alternatives could be completed within a short time period,
that is between 2 to 4 years. The short-term risks for all alternatives involve dust
emission due to the excavation of offsite soils contaminated with arsenic in levels
greater than 30 parts per million.
Alternative A-8, the preferred alternative, would contain the contaminated soil within an
estimated 2.25 years, with the least potential for short-term community risk involving
fugitive dust emissions during excavation and construction of the multi-layer cap than
any of the other alternatives. Two alternatives, A-1 and A-6, are estimated to be
implemented in 2.5 years. Alternative A-6 also includes the risk of dust production
during excavation and also during the treatment of the soil. Alternative A-7 is estimated
to require 3.75 years for implementation. It involves the risk of dust production during
soil excavation and during treatment. Additionally, Alternatives A-3, A-4, A-6, and A-7
would involve excavating onsite contaminated soils prior to their treatment which
increases the potential risk to the community.
Implementability. There are problems with both Alternatives A-1 and A-8 when
considering the technical and administrative issues to implementing them. Alternative
A-1 calls for all contaminated soils both offsite and onsite to be excavated and disposed
off site. Not only does CERCLA discourage offsite transportation and disposal of
contaminated materials, as in the case of Alternative A-1, but also the Federal
environmental regulations discourage just capping contamination without any treatment
as with EPA's preferred alternative, Alternative A-8. CERCLA has a preference for the
use of practicable treatment technologies where available. However, there are
implementation problems associated with the treatment technology alternatives and
there are serious doubts about the effectiveness and overall benefits provided by the
technologies that make them impracticable and/or inappropriate for the Crystal
Chemical site.
The Crystal Chemical site is 5 acres, the shallow ground water (water table) is
encountered at 15 feet, and the site is located in a part of Houston that is prone to
flooding. In fact, the Harris County Rood Control Channel forms the western boundary
of the site. The most heavily contaminated soils which would be excavated for
treatment are located at the northern boundary of the site, immediately adjacent to the
soon-to-be constructed Westpark Drive extension, therefore, the excavation and
treatment of the contaminated soils would have to carefully coordinated. Additionally,
the solidification/stabilization treatment technology (soil alternatives A-3 and A-6), as
previously identified, increases the volume of contaminated soil by 10% to 30% at a
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minimum. The soil volume increase that occurs when the soils in this area are
excavated is documented to be approximately 40%. This naturally occurring soil volume
increase of 40% coupled with the 10% to 30% increase will significantly increase the
volume of treated soil that will require permanent storage on the site thus creating a 19
foot high pile with alternative A-3. Furthermore, because untreated soils will remain on
the site, the multi-layer cap that must be constructed will add approximately 5 feet to
the treated soil pile with alternative A-€. Therefore, the end result could be a 9 to 15
foot stockpile and cap. The use of the available treatment technologies at the Crystal
Chemical site, consequently, is impracticable and inappropriate.
Cost The cost of the preferred alternative is $5,803,300, the lowest-cost alternative.
The highest-cost alternative is Alternative A-4 at $134,719,000. The other alternatives
range in cost from $84,266,100 for Alternative A-1 (offsite disposal) to $9,236,800 for
Alternative A-6 (solidification/stabilization and capping).
State Acceptance. The State of Texas, through the Texas Water Commission, was
given an opportunity to comment on the Amended ROD, however, they did not provide
any comments to EPA.
Community Acceptance. The community has voiced limited support for the Capping
remedy for the soil contamination at the Crystal Chemical site.
VIII. SELECTED REMEDY
Based on consideration of the requirements of CERCLA, the detailed analysis of the
alternatives, and public comments, EPA has determined that soil alternative A-8
(Capping) is the most appropriate remedy for the arsenic-contaminated soils at the
'Crystal Chemical site in Houston, Texas.
The remediation goal selected for the offsite arsenic-contaminated soils and sediments
is protective of human health and welfare and the environment The goal was selected
to eliminate or reduce risks associated with potential exposure to the contaminants via
ingestion or direct contact with soil, sediments and surface water, and inhalation of wind
dispersed dust. The goals for the soil contamination call for the removal of offsite soils
and sediments to a concentration of 30 ppm for arsenic, which represents a one in one
hundred thousand (10*9) excess cancer risk level. These soils will be placed back on
to the Crystal Chemical site.
Approximately 55,000 cubic yards of offsite soils and sediments contaminated with
arsenic above 30 ppm will be excavated and brought back on to the site. In order to
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ensure that all offsite soils and sediments contaminated with arsenic greater than 30
ppm from the Crystal Chemical site are identified, offsite areas previously identified as
contaminated will be resampled to verify the need for excavation. This will include, but
will not be limited to, adjacent properties, the Harris County Rood Control Channel, and
all properties potentially affected by drainage from the site by way of the flood control
channel.
During the design phase of the remedial action for the Crystal Chemical site, an
evaluation defining the relationship between the contaminated soils and the ground
water will be conducted. From this evaluation a determination will be made by EPA
regarding the potential success of achieving the remediation goal of 0.05 ppm of arsenic
given no source control at or below the ground water table. Given that there is heavily
contaminated arsenic-contaminated soils at or near the shallow ground water, the
necessity of the excavation of these soils during remediation will be evaluated.
IX. STATUTORY DETERMINATIONS
Under its legal authorities, EPA's primary responsibility at Superfund sites is to
undertake remedial actions that achieve adequate protection of human health and the
environment. In addition, Section 121 of CERCLA establishes several other statutory
requirements and preferences that the selected remedy must meet. Section 121 of
CERCLA specifies that when complete, the selected remedial action for this site must
comply with ARARs established under Federal and State environmental laws unless a
statutory waiver is justified. The selected remedy, also, must be cost-effective and utilize
permanent solutions and alternative treatment technologies or resource recovery
technologies to the maximum extent practicable. Finally, the statute includes a
preference for remedies that employ treatment that permanently and significantly reduce
the volume, toxicity, or mobility of hazardous wastes as their principal element. The
following sections discuss how the selected soil remedy meets these statutory
requirements.
Protection of Human Health and the Environment
The selected soil remedy protects human health and the environment by excavating all
offsite soils contaminated with arsenic above 30 ppm, placing these soils back on to the
site, and by capping the entire site. The site will be covered with a multi-layer cap to
act as a barrier that restricts the flow of water through the soils, prevents the release of
soil and contaminants into the air, and prevents direct contact with the contaminants.
Site access and land use restrictions prohibiting soil removal and any commercial or
residential activity will be implemented.
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Removing all offsite soils and sediments contaminated with arsenic greater than 30 ppm
will eliminate the threat of exposure from direct contact with the contaminated soils
outside of the current boundaries of the site. The current risks associated with these
exposure pathways from the contaminated soils are unacceptable. Therefore, the
residual contamination outside the current boundaries of the site after the completion
of the offsite portion of this remedial action will constitute a one in one hundred
thousand (10'*) cancer risk level. The construction of the cap over the entire site will
eliminate all threats relating to direct contact with and inhalation of the residual
contamination, and will act as a barrier restricting the flow of water through the soils.
This will reduce the risk posed by this site to less than one in one million (10"*). EPA
policy calls for remediation levels that range from a cancer risk of one in ten ttiousand
to one in one million (10"4 to 10"^. There are no short-term threats associated with the
selected remedy that cannot be readily controlled. Further, no adverse cross-media
impacts are expected from the soil remedy.
Compliance with Applicable or Relevant and Appropriate Requirements:
The selected soil remedy of excavation of offsite arsenic-contaminated soils greater than
30 ppm, placing these soils back on to the site, and capping the entire site will comply
with all applicable relevant and appropriate action-, chemical-, and location-specific
requirements ("ARARs"). The ARARs are presented as follows:
Action-specific Soil Remediation ARARs:
Applicable Resource Conservation and Recovery Act ("RCRA") requirements for
landfill closure, 40 CFR 264.111 Subpart G, which specify a cap with a
permeability less than or equal to the permeability of any bottom liner or natural
sub-soils present at the site. In addition, applicable specific closure
requirements which are provided for surface impoundments, 40 CFR 264.228
Subpart K, and applicable requirements for landfills. 40 CFR 264.310 Subpart N,
may also apply.
Post-closure and monitoring applicable requirements for 30 years or another
period determinedly the Regional Administrator, 40 CFR 264.117 (a)(1).
Applicable ambient air quality standards per 40 CFR 50 to protect the quality of
the air during the implementation of the remedial action.
Chemical-specific Soil Remediation ARARs:
As required by the Clean Water Act ("CWA") (33 CFR 303), onsite surface water
must meet applicable ambient water qualify criteria for arsenic (0.0175
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Location-specific Soil Remediation ARARs:
Applicable RCRA requirements, 40 CFR 264.18, for location of a Transportation,
Storage or Disposal ("TSD") facility in a 100-year floodplain, and also general
applicable requirements for protection of floodplains, 40 CFR 6, Appendix A.
Cost-Effectiveness:
The selected soil remedy is cost-effective because it has been determined to provide
overall effectiveness proportional to its costs, the net present worth value being
$5,803,300. While the selected soil remedy effectively reduces the hazards posed by
contaminants at the site, its costs are only 7 percent of the alternative involving total
excavation and offsite disposal, $84,266,100.
Utilization of Permanent Solutions and Alternative Treatment
Technologies (or Resource Recovery Technologies) to the Maximum Extent
Practical:
EPA has determined that the selected soil remedy in conjunction with the ground water
remedy selected in the 1990 ROD represent the maximum extent to which permanent
solution and treatment technologies can be utilized in a cost-effective manner for the
source control and remediation at the Crystal Chemical site. The soil remedy selected
in the 1990 ROD which consisted of using the ISV treatment technology remains to be
the best alternative to address the arsenic contamination at the site. However, the ISV
technology is not available at this time, and it is not known when the technology will
again become available for use at the Crystal Chemical site. Therefore, of those
alternatives that are available, protective of human health and the environment, and
comply with ARARs, EPA has determined that the selected soil remedy in conjunction
with the ground water remedy selected in the 1990 ROD provide the best balance of
trade offs in terms of long-term effectiveness and permanence, reduction in toxicity,
-mobility, or volume achieved through treatment, short-term effectiveness,
implementability, costs, also considering the statutory preference for treatment as a
principal element and considering State and community acceptance.
The selected remedy calls for capping all of the arsenic-contaminated soils above
acceptable health-based levels, which is soils contaminated with arsenic above 30 ppm.
The cap itself acts as a barrier that restricts the flow of water through the soils which are
not subjectecMo water table conditions, prevents the release of soil and residual
contaminants into the air, and prevents direct contact with the arsenic contamination.
Because the ground water extraction and treatment remedy selected in the 1990 ROD
will be implemented, the arsenic contaminated soils below the ground water table will
be treated. Through the extraction of the contaminated ground water, this source of
arsenic contamination will be eliminated. The arsenic contaminates adsorped to the soil
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process and extracted for treatment. The desorption and extraction of the arsenic will
make less arsenic available thus eliminating the source of arsenic contamination within
the ground water saturated zone and thus preventing further or continued release into
the ground water.
Although the capping remedy provides long-term reductions in the amount of water that
otherwise would pass through the contaminated soil thus creating long-term reductions
in the release of arsenic into the environment, the cap must be maintained to be an
effective barrier. The selected remedy will meet the ARARs for the site and is easily
implemented, but will not provide in reduction of toxicity, mobility, or volume of
contaminants through treatment. It is a cost-effective remedy, and it has been accepted
by the community. The State of Texas, through the Texas Water Commission, however,
did not provide any comments to EPA on the Amended ROD.
Preference for Treatment as a Principal Element:
EPA's selected soil remedy does not use treatment, however, the ground water remedy
selected in the 1990 ROD does utilize treatment to address the arsenic contamination
at the site at and near the ground water zones. The alternatives investigated for this site
that employ treatment would satisfy CERCLA's preference for remedies that employ
treatment that permanently and significantly reduces the volume, toxicity or mobility of
the hazardous substances, pollutants, and contaminants over remedies that do not
employ such treatment. However, the treatment technologies available for the Crystal
Chemical site do not afford a greater overall benefit because of the problems associated
with implementing them thus making them impracticable for the Crystal Chemical site.
Therefore, doing treatment for the sake of doing treatment using the available
technologies does not, in this case, appear to be appropriate or beneficial.
X. DOCUMENTATION OF SIGNIFICANT CHANGES
The Amended Proposed Plan for the Crystal Chemical site was released for public
comment in February 1992. The Amended Proposed Plan identified soils alternative A-8
(Capping) as the preferred alternative for the site. EPA reviewed all written and verbal
comments submitted during the public comment period. Upon review of these
comments, it was determined that no significant changes to the remedy, as it was
originally identified in the Amended Proposed Plan, were necessary.
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CRYSTAL CHEMICAL COMPANY SITE
RESPONSIVENESS SUMMARY
The Community Relations Responsiveness Summary has been prepared to provide
written responses to comments submitted regarding the Amended Proposed Plan at the
Crystal Chemical Company site. The summary is divided into two sections.
Section I. Background of Community Involvement and Concerns. This section
provides a brief history of community interest and concerns raised during the remedial
planning activities at the Crystal Chemical Company site.
Section II. Summary of Maior Comments Received. The comments (both oral and
written) are presented and EPA's responses are provided.
I. Background of Community Involvement and Concerns
The community has been involved on a iimited basis with activities at the Crystal
Chemical Company site. Members of the community attended the open house and the
public meeting in limited numbers, however, approximately 300 people receive mailings
from EPA on Crystal Chemical Company site activities. The comments that were
received from the local community concentrated on possible inconveniences that might
be experienced during and following the completion of the remedial action.
II. Summary of Maior Comments
Public notice announcing the public comment period and the public meeting was
published in the Houston Post on February 12, 1992. The Amended Proposed Plan
was distributed through the mail in early February 1992, and the public comment period
began on February 24, 1992 and ended on March 24, 1992. An informal Open House
was held in the area near the site on February 20,1992. The public meeting was held
on March 19, 1992 at the Westchase Hilton and Tower Hotel in Houston, Texas. The
purpose of this meeting was to discuss all the available alternatives and EPA's preferred
alternative for the soil contamination at the Crystal Chemical Company site.
Approximately 15 people attended the public meeting and three (3) people asked
questions or made comments. Four (4) sets of written comments were received during
the public comment period.
A. Comments and Questions received during the Public Meeting.
EPA received oral comments during a public meeting held at the Westchase Hilton and
Tower Hotel on March 19, 1992. Comments pertinent to EPA's Amended Proposed
Responsiveness Summary 1
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