United States Office of
Environmental Protection Emergency and
Agency Remedial Response
EPA/ROD/R09-91/068
September 1991
Superfund
Record of Decision:
Sola Optical USA, CA
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REPORT DOCUMENTATION 1" REPORT NO. I ~ 3. Recipient. Accesaion No.
PAGE EPA/ROD/R09-91/068
4. TIle and Subfte 5. Report Data
SUPERFUND RECORD OF DECISION 09127/91
Sola Optical USA, CA
6.
First Remedial Action - Final
7. AUlhor(.) 8. Performing Organization Rept. No.
8. Pwformlng Orgalnlzallon - and Add.... 10. ProjectfTaklWork Unit No.
11. Contnet(C) or Gron1(G) No.
(C)
(G)
12. ~ OrgarUatlon Name and AdcIre88 13. Type of Raport & Period Co-
U.S. Environmental Protection Agency 800/000
401 M Street, S.W.
Washington, D.C. 20460 14.
15. SuppIamentary No...
16. Abatr.ct (u.nt: 2DO _rd.)
The 35-acre Sola Optical USA site is an active ophthalmic lens manufacturing facility
in southern Sonoma County, California. Land use in the surrounding area is mixed
residential, manufacturing, commercial, and undeveloped. Adobe Creek is located 1500
feet west of an onsite building. The city of Petaluma utilizes an unconfined
aquifer, which underlies the site, as a drinking water source. In 1982, Sola
identified low levels of solvents in onsite ground water near six underground solvent
storage tanks used to store TCA, acetone, and methanol. In 1983, the San Francisco
Regional Water Quality Control Board (SFRWQCB) directed Sola to investigate ground
water contamination at the site. In 1985, Sola independently excavated and removed
the underground tanks along with the gravel backfill and 3 to 5 feet of native soil
from the sides and bottom of the excavation. In 1987, the SFRWQCB ordered Sola to
construct a ground water extraction and treatment system and, in 1988, the treatment
system began pumping and treating ground water using granulated activated carbon to
remove VOC contamination, followed by discharging the treated ground water under
permit to Adobe creek. This Record of Decision (ROD) provides a final remedy to
(See Attached Page)
17. Document An8/y8I8 L De8alpIO..
Record of Decision - Sola Optical USA, CA
First Remedial Action - Final
Contaminated Medium: gw
Key Contaminants: VOCs
b. Idonllfi8nalOpen-End8d Tenna
Co COSA 11 AeIdIGroup
18. AvliJabiity SUI8m8nt 18. Sea8ity CI... (Thla Report) 21. No. of P.II"
None 36
20. Secui1y CI... (ThI8 Page) 22. PrIce
Non!'>
Ufo'IiUNAL t-UHM 272 (..,,)
50272.101
(See ~Z3I.18)
s.. m.1ructj0fl8 on ~-
(Formerly HTlS-35)
Deper1men1 of Commerce
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EPA/ROD/R09-91/068
Sola Optical USA, CA
First Remedial Action - Final
Abstract (Continued)
restore ground water to its beneficial use.
affecting the ground water are VOCs.
The primary contaminants of concern
The selected remedial action for this site includes installing additional extraction
wells onsite; continuing pumping and treatment of ground water using the existing
granulated activated carbon adsorption system, followed by discharging the treated water
onsite to surface water, or discharging the extracted ground water offsite with or
without treatment to a publicly owned treatment works (POTW); disposing of any spent
carbon offsite; and ground water monitoring. The estimated present worth cost for this
remedial action ranges from $2,100,000 to $2,200,000 depending on the treatment
selected, which includes an annual estimated O&M cost of $169,000 for 15 to 20 years.
PERFORMANCE STANDARDS OR GOALS: Chemical-specific ground water clean-up goals are based
on SDWA MCLs and State standards.
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SOLA OPTICAL SUPERFUND SITE
RECORD OF DECISION
u.s. EPA
.
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Concurrences
Sola Optical Site
Record of Decision
Nora McGee
Assistant Regional Administrator
Office of Policy and Management
Nancy Marvel, Regional Counsel
Office of Regional Counsel
Harry Seraydarian, Director
Water Management Division
1/ U/'7/
Date
Date
Date
Date
-------
Concurrences
Sola optical Site
Record of Decision
David Howekamp, Director
Air and Toxics Division
II aM-- j11 ~
No a McGee
Assistant Regional Administrator
Office of Policy and Management
Nancy Marvel, Regional Counsel
Office of Regional Counsel
Harry seraydarian, Director
Water Management Division
Date
1-75-1{
Date
Date
Date
-------
Concurrences
Sola Optical site
Record of Decision
David Howekamp, Director
Air and Toxics Division
Nora McGee
Assistant Regional Administrator
Office of Policy and Management
-l /4 --/11 e
/.: ";V1, \" U ,-j' _.- I. I BVvc!-{..'---
Nancy M~tvel, Regional Counsel
Office of Regional Counsel
Harry seraydarian, Director
Water Management Division
Date
Date
~ r ~/. ;21, / '1/ /
Da e -
Date
-------
Concurrences
Sola optical Site
Record of Decision
David Howekamp, Director
Air and Toxics Division
Nora McGee
Assistant Regional Administrator
Office of Policy and Management
Nancy Marvel, Regional Counsel
Office of Regional Counsel
JfJ,~ 7b.~ '--
~A~arry Seraydarian, Director
~VWater Management Division
Date
Date
Date
SEP 2 4 1991
Date
-------
Hazardous Waste Management Division
Concurrence
Sola Optical sit.
Record of Decision
son, Dl.rector
Waste Management Division
.
9-27-tfr
Date
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T ABLE OF CONTENTS
fm
List of Figures.... ............ [[[ ii
List of Tables....................... [[[ ............................ ii
Declaration for the Record of Decision[[[ 1
Decision Summary[[[ """""'"'''''''''''''''''''''''''''' 3
I.
II.
HI.
IV.
V.
VI.
VII.
VIII.
IX.
x.
Site Name, Location and Description.............................................. 3
Site History and Enforcement Activities..........................................5
Highlights of Community Involvement........................................... 6
Scope and Role of the Response Action...........................................6
Summary of Site Characteristics[[[ 7
Summary of Site Risks[[[ 12
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Figure #1
Figure #2
Figure #3
Figure #4
Table A
Table B
Table C.
Table D
Table E
J
LIST OF FIGURES
fm
Site and Vicinity Map[[[ 4
Chemical Concentrations Detected in Soil-Gas Samples-
April 1990[[[ ....... ...........................8
Site Plan....... .............. [[[ ........... ...1 0
VOC-Contaminated Groundwater by Depth, with Shallow Capture
Line - April 1990 [[[11
LIST OF TABLES
fm
Chemicals of Concern.. ............. ........... ......................... ................. .13
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Declaration for the Record of Decision
SnENAMEANDLOCATION
Sola Optical USA, Inc.
1500 Cader Lane
P.O. Box 6002
Petaluma. CA 94953-6002
STATEMENT OF BASIS AND PURPOSE
This decision document presents the remedial action selected for the Sola Optical USA (Sola) site in
Petaluma, California. This remedial action was chosen in accordance with the Comprehensive Environ-
mental Response Compensation and Liability Act (CERCLA), as amended by the Superfund Amend-
ments and Reauthorization Act (SARA), and, to the extent practicable, with the National Oil and
Hazardous Substances Pollution Contingency Plan (NCP). This is the first and final remedy and there
are no additional operable units.
This decision is based on the administrative record for this site. The attached Administrative Record
Index (Attachment A) identifies the documents upon which the decision is based.
The State of California concurs with the selected remedy.
ASSESSMENT OF THE SnE
Sola discovered solvents in the groundwater and in the soils adjacent to their underground storage tanks.
Sola removed the underground tanks and the adjacent soils. Sola has constructed and is presently
operating a groundwater extraction and treatment system. However, residual groundwater contamina-
tion requires that additional work, as actual or threatened releases of hazardous substances from this site,
if not addressed by implementing the response action selected in this Record of Decision (ROD), may
present an imminent and substantial endangerment to public health~ welfare, or the environment.
DESCRIPTION OF THE REMEDY
The selected remedy for contaminated groundwater at the Sola site consists of:
groundwater monitoring to demonstrate capture of the contaminant plume and
ultimately, achievement of the cleanup standard;
operation of existing extraction well system;
construction and operation of two additional extraction wells and piping; and
conversion of two deep monitoring wells to extraction wells.
1
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By fully addressing the groundwater contamination at the site, the remedy would reduce the principal
risk from the site. Sola addressed the principal threatS posed by the site when they removed the
underground tanks and the contaminated soils adjacent to the tanks. These interim actions, conducted
prior to EPA involvement, were not inconsistent with the fmal remedy chosen by EPA.
Implementation of this remedy will increase the rate of groundwater cleanup in an area where the
groundwater contamination is highest It will also address the low levels of contamination found in two
deeper on-site monitoring wells. This groundwater extraCtion system will operate until the cleanup
standards are achieved. Until these standards are achieved, evaluation of the remedy will continue at a
frequency to be determined during the remedial design.
ST A roTORY DETERMINATIONS
The selected remedy is protective of human health 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 uses permanent solutions and alternative treatment technologies to the maximum
extent practicable and satisfies the statutory preference for remedies that employ treatment to reduce
toxicity, mobility, or volume as a principal element
e .
v-J \4A.-
Daniel W. cGovem k
Regional Administrator
&f.l7. eu
Date
2
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Decision Summary
I.
SITE NAME, LOCATION AND DESCRIPTION
SITE NAME AND LOCA nON
The Sola site is located in southern Sonoma County. California. on the southeastern edge of the
City ofPetaluma (See Figure 1). Sola has been manufacturing ophthalmic lenses since 1978 at its 35-
acre facility in Petaluma's industrial area. The facility address is 1500 Cader Lane and is located just
west of Lakeville Highway, south of the Lakeville Highway intersection with Route 101. The facility
comprises a manufacturing building and an adjoining administration office building. The former under-
ground storage tanks were located behind the rear north comer of the manufacturing pan of the facility.
Sola manufactures hard-resin ophthalmic lenses. The manufacturing process involves the
injection of a catalyzed, thermosetting resin into a cavity between polished glass molds. The mold
assembly is subsequently placed in an air oven to cure the resin. The assembly is removed from the oven,
the cured resin lenses removed from the assembly, and the assembly is put through a cleaning process
before production is repeated.
REGIONAL TOPOGRAPHY
The topography of the area, including the site itself, gently slopes at a rate of 50 feet permiJe from
low hills in the east towards the Petaluma River, located about one mile southwest of the 501a building.
Adobe Creek is located 1,500 feet west of the 501a building. Adobe Creek intermittently flows in a
north-south direction.
HYDROGEOLOGY
Sola has conducted geologic investigations at the Site. Sola's investigations have revealed that
the depositional sequence of sediments below the surface at the site consists of a complex sequence of .
interbedded clays. silts and sands, with lesser amounts of gravel. Shallow sediments represent a complex
sequence of alluvial deposits. At depths below the surface of approximately 80-100 feet, thicker clay
interVals were encountered which appear to be relatively continuous over distances of hundreds of feet.
Interbedded within these clay intervals are silt, sand, and gravel intervals of various thicknesses. These
deeper sediments probably represent complex depositional environments that involve both alluvial and
estuarine deposition. Groundwater in shallow sediments in the site vicinity is generally encountered at
elevations 9 to 12 feet below ground surface.
Groundwater flows in a south/southwest direction towards the Petaluma River, which is the most
likely point of discharge. Natural recharge occurs at the base of the foothills to the nonhlnortheast.
Testing of the aquifer was condu~ in October 1987 by Sola under the direction of the San Francisco
Regional Water Quality Control Board (SFR WQCB). This aquifer is unconfined and has been classified
by EP A as a class DA drinking water source aquifer.
3
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ft
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LAND AND WATER USE
The facility is located in an area zoned for indusnial uses. Adjacent property to the west is owned
by Stern Company. a manufacturer of dishwashers. There are residential subdivisions approximately
300 feet to the northwest and there is undeveloped land to the north. Fireman's Fund Insurance, the
RUSS Company, and TegaJ Corporation occupy office space to the east of the Sola property. Property
to the south remains undeveloped and was fonnerly a private residence.
Two private wells operated previously in the vicinity of the Sola facility. the 5 tero industrial well
(approximately 1.000 feet west, down gradient of the facility) and the Crandell residential well
(approximately 1.500 feet southwest. downgradient of the facility). The owners of these two wells are
now supplied with water from the CityofPetaluma. In addition. there is a City ofPetaluma (Station #5)
municipal water supply well,located 300 feet north of the site and a city well on the Sola propeny that
has never been used. In 1988. Sola entered into a written agreement with the City of Petaluma. The
City agreed to discontinue use of Station #5 well to ensure that the operation of the municipal well does
not disrupt the ongoing groundwater clean-up operation by drawing down groundwater elevations in the
unconfined aquifer below the screened intervals of the extraction wells.
Sola has sampled the Station #5 municipal well on 14 occasions between 1986 and 1989.
Analysis of these samples did not reveal the presence of any contaminants which exceeded the 5 tate or
Federal drinking water standards. Sola also sampled the Stero and ~dell wells six times each between
1987 and 1990 and the results did not exceed the 5 tate or Federal drinking water standards.
n.
SITE HISTORY AND ENFORCEMENT ACTIVITIES
In May 1982, Sola identified low levels of solvents in groundwater under the Sola propeny near
six underground solvent storage tanks. Sola used these six 1.000 gallon underground tanks to store 1.1.1-
nichloroethane 0.1.1 TCA}. acetone. and methanol. In 1985. Sola independently removed the under-
ground tanks. The removal of the tanks reponedly included the excavation of gravel back-fill and an
additional three feet of native soil from the sides and bottom of the tank excavation. Sola collected 22
soil samples from the excavation pit. Based on. the. analysis of these soil samples. Sola excavated an
additional two feet from the eastern wall of the excavation pit. Additional samples taken following the
excavation indicated the presence of volatile organic compounds (VOCs); however. no additional
excavation was conducted.
Sola's early investigation also confirmed that groundwater at the site was contaminated with
VOCs, including 1.1.1- TCA. 1.I-dichloroethene O.l-DCE). 1.1~ichloroethane O.I-DCA). and meth-
ylene chloride. EPA considers these compounds hazardous to human health and the environmenL
In 1983. the SFR WQCB directed Sola to investigate the groundwater at the site. In 1987, the
SFRWQCB issued Sola a Cl~up Order #87 -038 to construCt a groundwater extraction and treatment
system. Sola was proposed for the National Priorities List (NPL) in June 1988. Sola began operating
its groundwater extraction and treatment system in August of that same year. Sola currently discharges
the treated groundwater to Adobe Creek under a National Pollution Dicharge Elimination System
(NPDES) permit from the SFRWQCB.
5
,
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EPA conducted research to identify potentially responsible parties (PRPs), those panies who
may be liable pursuant to CERCLA, for the investigation and cleanup of contamination at the site. Sola
was the only PRP identified during this investigation. General and Special Notice was issued to Sola
prior to negotiations. Sola has financed and conducted a Remedial Investigation/Feasibility Study (RV
FS) under an EPA administrative consent order (docket #89-22) signed in October 1989. Sola has paid
past costs and oversight costs incurted by EPA through June 1990.
The Remedial Investigation included sampling of soils, soil gas, and groundwater. The
Remedial Investigation Repon, which summarized these activities, was submitted by Sola on December
3. 1990. EP A completed the Risk Assessment in April 1991. The Feasibility Study was submined by
Sola on June 10, 1991.
m.
HIGHLIGHTS OF COMMUNITY INVOLVEMENT
The Community Relations Plan (CRP) was developed in-house by EPA's community relations
staff, following EP A guidance. Consistent with the recommendations of the CRP. the Project Manager
briefed the Petaluma City Council and issued a fact sheet announcing the administrative consent order
and the commencement of the RIlFS. The City Council meeting took place on October 19, 1989. The
fact sheet was mailed to area residents during the same period and generated few inquiries.
In February 1991. following the completion of the remedial investigation, EP A issued another
fact sheet summarizing the findings to the public. No responses were received following distribution
of this fact sheet
The public participation requirements of CERCLA Sec. 113(k)(2)(B)(i-v) and 117 were met in
the remedy selection process. In June 1991 EPA issued the proposed plan. An announcement was
printed in the Santa Rosa Press Democrat on June 17. 1991. announcing the public comment period and
the public meeting. EPA held the public meeting on June 25.1991, in the Veterans Memorial Building
in Petaluma. California Departtnent of Health Services and four members of the community attended
the meeting. EP A received only one comment lener during the public comment period. which officially
closed on July 16, 1991.
Details of community involvement activities and responses to public comments on the Proposed
Plan are presented in the Responsiveness Summary (Attachment B).
IV.
SCOPE AND ROLE OF THE RESPONSE ACTION
Interim cleanup of the groundwater and the contaminated soil has occurred. Sola addressed the
principal threats by removing the underground tanks and contaminated soils adjacent to the tanks. The
residual extent and concenU'ation dr contamination in the soils do not present a significant threat, based
on the results of the risk assessment and a groundwater model.
6
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The actions conducted by Sola under the direction of the SFRWQCB have panially addressed
the risk from contaminated groundwater and have anempted to halt orreduce the spread of contaminated
groundwater but were not intended to be a final remedy. The selected final remedy addresses the
remaining risks posed by the contamination in groundwater. The remedy will eliminate the potential for
human exposure to contaminants through the ingestion and inhalation of contaminants in the ground-
water.
The reduction of risk will be achieved by the hydraulic capture of contaminants in groundwater
through the use of groundwater extraction wells. The existing system will be enhanced with tWo new
shallow extraction wells and tWo deep extraction wells (convened from monitoring wells). Groundwa-
ter with contaminant concentrations aboye the State drinking water standards will be pumped into the
extraction system.
Extracted water will either be treated with the existing carbon f1lter system at the facility and
discharged off-site or discharged to the City sewage treattnent system with or without treattnent. The
City of Petaluma has an industrial discharge limit of 1 pan per million (ppm) for total toxic organics.
Monitoring results from the extraction system indicate that concentrations in groundwater are presently
low enough to meet this staildard without treatment
There are no additional operable units, and no further action is warranted for soils.
v.
SUMMARY OF SITE CHARACTERISTICS
SOIL CONTAMINATION
In July 1985, Sola independently removed six underground storage tanks. Sola contractors
reponed that they observed no evidence of leakage during the tank removal, which indicated to them,
the release of contaminants could have been the result of accidental spillage. .
The removal of the tanks included the excavation of back-fill material and approximately 3 feet
of soil from the sides and bonom of the tank excavation. Samples were taken from the pit after the
excavation. Analytical resultS for the samples collected from the excavation pitS revealed the presence
of acetone, ranging in concentrations from 1.1 to 54 ppm. Concentrations of 1,1 DCE were detected at
10 partS per billion (ppb). An additional two feet of soil was excavated from the eastern wall of the pit
where the acetone was detected.
In July 1986, Sola independently conducted a soil gas investigation. Soil gas samples were
collected from 48 locations. The highest VOC concentration was 250 milligrams per liter of 1,1,1- TCA.
In April 1990, EPA required Sola to collect and analyze samples of sub-surface soils and soil
gases. The soiJ gas survey inclLded samples from 40 locations at depths ranging from 2 to 9 feet. The
results are presented in Figure 2. The lateral and vertical distribution of VOCs and the magnitude of
VOC concentrations detected in soil gas do not currently indicate the presence of a principal threat in
soil.
7
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FIGURE I 2
AoMmO?. 01
TCA OOOOS. 00001
4/1 AaMoMOOt. 001
PCE 00004. 0 00001
TCA oooo}. 0004
IH TCA 00002
PCE 000004
4/5 TCA 00005
PCE 0.00004
^s^• BJJUI' ' f mt\
^^ JX2* f 1!
<"» 3!»V 001 TCK*
l.i-tct
• : ,, 1.1-tCA ,
»i. Tc* ''
0.0004 TCE . '.i
0.001 PCE
04 no
0.9 TCA
OOOO TCE
O.OO4 PCE
O.I ArclaM
o« i.i-ncc
CMEMICAl CONCENTRATIONS DETECTED IN
SOU-GAS SAMPtES Oig/l). APRIL 1990
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Sola collected soil samples from six soil borings near the fonner location of the storage tanks.
. l,l-DCE was detected at a maximum concentration of 51 ppb.
EP A required Sola to use a contaminant transpon model to determine whether the contaminated
soil would funher contaminate the groundwater. The results of the model indicated these soils do not
pose a principal threat of funher contaminating groundwater.
GROUNDW A TER
Sola conducted hydrogeologic investigations at the site. Figure #3 provides a site diagram
locating all site wells. The aquifer beneath the Sola facility, as described earlier, isunconfmed and flows
in a south/southwest direction. VOC-contaminated groundwater extends from behind the Sola building
(where the underground tanks were formerly located) to the southwest corner of the Sola propeny. The
focus of the groundwater investigation was to assess the extent of contamination outside the zone of
capture of the extraction system constructed under the 1987 SFRWQCB Order.
In 1990, Sola installed nine additional monitoring wells. Samples taken from these and existing
groundwater monitoring wells confinned that the VOC-contaminated groundwater (at concentrations
above clean-up standards) is largely limited to the Sola propeny (see Figure #4). These wells (LF-21
through LF-28) were installed:
to confmn down gradient lateral and vertical extent of VOC-contaminated groundwater;
and
to evaluate the distribution ofVOC-affected groundwater in the deep sediment intervals
tapped by the City of Petaluma (Station #5) municipal well.
Water quality data from these new wells achieved these objectives. The primary VOCs detected
in groundwater samples from monitoring wells at the site are 1,1- DCA; 1,1- DCE; 1,1,1- TCA; and Freon
113.
The highest concentrations of the primary VOCs have been detected in groundwater samples
collected from shallow well W14, which is located down gradient of the vicinity of the former storage
tanks. Water quality data from wells located on the downgradient edge of the Sola propeny (W33, LF-
25, LF-26 and LF-28) indicate that the lateral extent of VOC-contaminated groundwater within the Sola
property is at or below the clean-up standards. Figure #4 shows the distribution ofVOC-contaminated
groundwater at shallow, intermediate, and deeper intervals. The VOC-contaminated groundwater in
deeper intervals does not meet clean-up standards in wells LF-17 and LF-13 and is not within the capture
of the current extraCtion sYStem
DATA QUALITY
j
EPA has collected split samples and independently analyzed these as a part of oversight
activities. EP A also had an independent contractor validate this data. Quality control criteria were met
for 98% of the data. EP A data and data collected by Sola are in good agreement. The relative percent
difference, an indication of precision, is less than 50% for the 15 sample pairs available for comparison.
EPA split data represents 20% of the total data used in the groundwater calculations in the risk
assessment.
9
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MCL'. IN SHALLOW, INTERMEDIATE.
DE£P, AND DE9£R-OEPTH OAOUNDWATER
APRIL AND AUOUST 1890
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VI.
SUMMARY OF SITE RISKS
HUMAN HEAL1H RISKS
The purpose of the Risk Assessment was to evaluate the public health and environmental risks
posed by VOCs detected in groundwater, soil, and soil-gas at the Sola site. The Risk Assessment Repon
was completed by EP A's contraCtor in April 1991. Twelve VOCs at the site were identified as chemi-
cals of potential concern. The twelve chemicals of potential concern are presented along with their
respective toxicological data in Table A.
The exposure assessment evaluated potential exposure pathways for the chemicals of potential
concern in groundwater, soil, and soil gas. The Risk Assessment assumes the maximum exposure
scenario. The exposure scenario assumes residential use of the groundwater. Pathways of exposure
include groundwater as a drinking water source and VOCS transponed from groundwater or soil into
household air (eg., from showering and other domestic uses of water or soil gas that would seap directly
into buildings). Routes of exposure include ingestion of drinking water, dermal contact, and inhalation
of VOCs. The exposure assumptions used in the Risk Assessment are presented in Table B. The
concentrations used to calculate risk for soil gas exposure is based on a maximum concentration. The
concentrations used to calculate risk for groundwater exposure is based on the 95% upper confidence
limit on the mean concentration.
The toxicological assessment divided the twelve chemicals of concern by their carcinogenic or
non-carcinogenic effects. Six chemicals of concern were classified as known, probable, or possible
human carcinogens. The potential for carcinogenic effects was evaluated by estimating excess lifetime
cancer risk. Non-carcinogenic risk was assessed by comparing the estimated daily intake of a chemical
to the EP A-estimated safe level of daily exposure, or reference dose.
Soil Gas! Air Risks: EP A estimated potential health risks associated with soil gas contamination
at the Sola propeny based on diffusion of soil gas into the air of a building built over the area of soil and
groundwater contamination. Of the twelve chemicals of potential concern, ten were detected in soil gas.
The ten chemicals of potential concern in soil gas were used to calculate the risk posed by soil gas
contaminantion at the site. The ten chemicals of potential concern for soil gas are presented in Table
C along with the concenttations used to calculate the risk, the individual cancer risk associated with each
chemical at the concentration detected. and the non-carcinogenic risk. The excess lifetime cancer risk
for exposure to soil gas in air is 9x 10-6 (9 persons out of 1.000.000 people). as presented in Table C. The
non-carcinogenic health risks estimated by the Hazard Index rating indicates that no adverse health
effects are expected. In addition. 501a is an active manufacturing facility zoned for industrial use.
Groundwater Risks: The Risk Assessment provides an estimate of carcinogenic and non-car-
cinogenic effects from the domestic use of groundwater at the Sola site. Of the 12 chemicals of potential
concern, four contaminants were detected in groundwater. The four chemicals of potential concern and
the estimated risk for groundw'ater are included in Table D.
12
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TABLE A
.....
w
r.lw8lnh ., «:-..
5Js8ntk T.ddty C8ft1 '1l1li: r~
C......,. (......,..1
0nIsa. W..... ., I.' ... ....... ..
a..IaII 0nI 8ft) ........ I"""'''' Rm R~frftllft f.- E9111rnft8 IbftftMt ... ...... E.....8 -..-
Amme 0.1 IRIS .. .. .. .. .. .. .. -
nutanme .. .. .. " " - - - - -
1.1.1>idl1nmdfuN8e I" HFA"T 0.1 IfF.AST .. C IRIS - C IRIS
1.2.DktlInmdr-e - .. .. .. 0.091 8J IRIS 0.091 82 IRIS
1.I.DldllhructIlatc 1.009 IRIS .. .. 0.6 C IRIS 1.2 C IRIS
FftI08 II J 38 IRIS .. ., .. .. .. .. - -
4.Mdr.,t.2..-...,. O.~ IRIS 0.02 HF.Mf .. - - - - -
Trtrdlnmdine 0.01 IRIS - .. 0.051 82 HEAST 0.0011 92 HF..AST
TnI- U IRIS '.n Ilr-.A.~ .. .. - - - ..
1.1.1- Tridllnmdllalle '.09 IRIS O.J IfF..AST .- - .. - - ..
1.1.2- Tridllnmdllalle 0.004 IRIS .. .. 0.057 c . IRIS 0.057 C IRIS
T.....lonJdhalc .. .. -. -. 0.011 02 HF.Mf 0.017 82 HI!AST
8r...., B: ...... h- an::11IeJIaI. SaRideftI ~ III ...1...... and illllClequate or 110 nicImce In ""........
GI'OIIp C: Pa8lbIe -- C8fd808cL Unlitat nicImce 01 C8mnoaaicity In ani...... 18 the at.cnn: 01 h._n cIata.
Nc1ca:
IIF.AST HaIIh MIICta ~.. S-IJ TaNe. u.s. ErA 199Oh.
IRIS 18tqratat Rilt l8Ionnatlo8 System. U.s. ErA. 19901.
.. Infonnallo8 ..... 8V8i1a..
-------
The major contributor to both estimated cancer and non-cancer risks is 1,1 DCE. Only 1,1 DCE
has a numeric factor that can be used to calculate cancer risk. The excess lifetime cancer risk presented
by use of on-site contaminated groundwater for drinking water is 1 x 10-4 (1 person out of 10,000 people).
The non-carcinogenic risk estimate for contaminated groundwater indicates that no adverse non-
carcinogenic health effectS are expected.
The calculated Vex: concentrations in groundwater were based on the average water quality data
from 28 monitOring wells. The calculated concentration for 1,1 DCE was 6.1 ppb, which is close to the
clean-up standard and reflectS approximately the same amount of risk as the clean-up standard. The
estimated risk for 1,1 DCE at the clean-up Standard of 6 ppb is also lxlo....
ENVIRONMENTAL RISK
An Ecological Assessment was prepared as a pan of the Risk Assessment. The Ecological
Assessment focused on Adobe Creek. Adobe Creek is the closest surface water body and is the site of
a local project to reintroduce anadromous steelhead trout to the creek.
Water quality samples from groundwater monitoring wells installed between the Sola propeny
and Adobe Creek have not detected any contaminants, indicating that discharge of contaminants to
surface water has not occurred. In the absence of the current extraction system, groundwater from the
Sola facility would flow in the direction of Adobe Creek; however, contaminants detected in ground-
water at the site are below their cOITesponding federal surface water quality criteria for the protection
of aquatic life.
SUMMARY
Releases of hazardous substances from the site presented the potential for an imminent and
substantial endangerment to public health, welfare and the environment. Interim pumping and treatment
of groundwater and removal of tanks and contaminated soil has reduced site risks; however, groundwa-
ter beneath the site still exceeds drinking water standards and warrants remedial action.
TABLE B
Assumptions used ia Future-Use Scenarios
Parameter Intake Value.
Ingestion Rate 1 liter/day (child)
2 liter/day (adult)
Inhalation Rate 20 m'J/day (adult)
Body Weight ., 10 kg (child)
70 kg (adult)
Exposure Frequency 365 dayslyear
Exposure Duration 30 years
Years in Lifetime 25,550 days (70 years)
.Source: U.S. EPA, 1989a, 1989b, and 1989c.
14
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TABLE C
Risk Characterization-Air Pathway
Air Excess Ufetime
Concentration. Cancer Risk
Chemical (~gII) Estimate Hazard Index
Acetone 4.0 x 10-7 - 1.1 x 1O~
1,1- Dichloroethane 9.9 x 10~ - 2.8 x lO-s
1,2-Dichloroethane S.9 x 10-7 6.6 X 10-9 -
1,1-Dichloroethene S.8 x lO-s 8.S x 10~ 1.6 X 10-3
Freon 113 6.S x 10-7 - 6.2 X 10-9
T etrachJoroethene 4.0 x 10-8 8.8 x 1O-1:Z 1.1 x 10~
Toluene 4.7 x 10-7 - 2.3 X 10-7
1,1, I-Trichloroethane 4.S x 1.0~ - 4.3 x 10~
1,1,2- Trichloroethane 2.S x 1O~ 1.7 X 10-8 1.9 x 10";
Trichloroethene 7.S x 10-8 1.6 X 10-10 -
Total Risk 9 x 1 O~ 0.002
I "Maximum concentrations I
~
TABLE D
Risk Characterization--Groundwater Pathway
Groundwater
Concentration. Cancer Risk
Chemical (mgll) Estimate" Hazard Index
1,1- Dichloroethane 0.0011 - 0.0022
1,I-Dichloroethene 0.0061 1.4 x 10-4 0.14
Freon 113 0.00063 - 0.0000042
1,1, I-Trichloroethane 0.0029 - 0.0042
Total Risk 1 x 10-4 0.1
agS percent upper confidence limit on mean concentration
bIngestion and inhalation routes summed together. The hazard index is based on
a child exposure scenarib.
15
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VII.
DESCRlYfION OF AL TERNA TIVES
This section will describe alternatives developed in the Feasibility Study. The five extraction
alternatives were evaluated and compared to the nine criteria required by the NCP (40 CFR Sec.
300.430(e)(9». The nine criteria are: overall protection of human health and the environment;
compliance with applicable, or relevant and appropriate requirements (ARARs); long-term effective-
ness and permanence; reduction of toxicity, mobility, or volume through treatment; shon-term
effectiveness; implementability; cost; state acceptance; and community acceptance. The nine criteria
are described in more detail in Pan VITI of this decision document, entitled Summary of Comparative
Analysis of Alternatives.
Each one of the alternatives in the Feasibility Study, with the exception of the no-action
alternative, complies with ARARs for the site. To comply with ARARs, an alternative must meet all
substantive Federal and State environmental laws and regulations.
The groundwater contamination at the Sola site is in a groundwater aquifer that has been
designated as a source of drinking water and has actually been proven to be in the same unconfined
aquifer used by the City of Petaluma municipal well (station #5 well). For these reasons, ground water
must be restored to State and Federal drinking water standards. The drinking water standards or clean-
up standards for the four contaminants identified in groundwater are presented in Table E. The
Table E
Primary VOCs in Ground Water and Clean-up Standards
1990 Maximum Drinking Water Clean-up
Concentration (ppb) Standards (ppb) Standards (ppb)
Chemical Shallow Deep State Federal
1,1 DCE 1,400 22 6 7 6
1,1 DCA 280 1 5 5
1,1,1 TCA 220 10 200 200 200
Freon 113 9 2 1,200 - - 1,200
alternatives described below, except the no-action alternative, are designed to meet these standards in
the aquifer over different restoration time periods.
Attainment of these levels in the aquifer will be protective of human health and the environment.
However, EP A recently studied the effectiveness of groundwater extraction systems in achieving
specified goals and found that it is often difficult to predict the ultimate concentration to which
contaminants in the groundwater may be reduced. Nevertheless, the study verified that groundwater
extraction is an effective cleanup measure and can achieve significant mass removal of contaminants.
The remedial alternatives described in this section are all based on extraction systems. The Agency
16
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believes it is technically feasible to achieve the cleanup standards in the groundwater using extraction
systems.
After the contaminated groundwater is extracted it may be discharged to a surface water body
or to the local sewer system. These discharge options apply to all of the alternatives with the exception
of the no-action alternative.
If the water is discharged off-site to Adobe Creek it must be treated with the activated carbon
filter system at the facility. Alternatively, the water may be discharged to the city sewage treabnent
facility. The City of Petaluma has an industrial discharge limit of 1 pan per million for total toxic
organics. Monitoring results from the extraction system indicate that contaminant concentrations in
groundwater are presently low enough to meet this standard without treatment.
Each alternative will require periodic groundwater monitoring to determine its effectiveness and
to verify achievement of the cleanup standards. The specific groundwater monitoring program will be
defined more precisely during Remedial Design/Remedial Action.
If the carbon filter treatment system is used, spent carbon must be handled in compliance with
the requirements of the Resource Conservation and Recovery Act (RCRA) and the California Hazardous
Waste Control Law if waste (i.e. spent carbon) is stored for more than 90 days at the site.
ALTERNATIVE #1 - NO AcrION
The NCP requires that a no-action alternative be considered at every site. The no-action
alternative serves primarily as a point of comparison to other alternatives. This alternative is evaluated
to detennine the risks that would be posed to public health and the environment if no action were taken.
With this alternative. the existing groundwater extraction treatment system would be shut down.
However, long-tenn monitoring of the site would be necessary to monitor contaminant migration.
Monitoring, using existing monitoring wells. can be easily implemented. Alternative #1 would rely on
natural processes in the groundwater to achieve cleanup standards. The time required for natural
processes to reduce contaminant concentrations to the cleanup standards is estimated to be 500 years.
. .
The annual operation and maintenance (O&M) cost for alternative #1 would be $70,000. Since
the alternative requires "no-action" there would be no capital cost.
. ALTERNATIVE'2
Alternative '2 is the continued operation of the current groundwater extraction system at the
current rate of 25-30 gallons per minute (gpm). The current system pumps groundwater from eight
existing extraction wells, each of which draw water from 20 .10 30 feet beneath the ground surface.
Calculated time to achieve cleanuf Standards for this remedy is 25-30 years.
This alternative would provide capture for contaminanted groundwater with VOC concentra-
tions above the cleanup standards in Table E. near the surface of the water table and down to
approximately 40-50 feet. VOCs have been found at concentrations which do not meet their respective
cleanup standards at depths below the capture of the current system. Under Alternative #2, these con-
taminants would be left to degrade through natural processes.
17
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If the water is discharged off-site to Adobe Creek it must be treated with the activated carbon
filter system at the facility. Alternatively, the water may be discharged to the city sewage treatment
facility. .
The net present value cost for this 25- 30 year project would range between $2.5 and $2.7 million.
Capital costs would range up to $8,000 (piping and hook - ups), and annual O&M costs would be between
5153,166 and $166,650.
ALTERNA 11VE *3
Alternative *3 is the continued operation of the CUITent extraction system with two additional
shallow extraction wells. These wells would be placed in an area of high VOC concentration, reducing
the estimated clean-up time to 15-20 years.
This alternative would provide capture for those contaminants, at concentrations which do not
meet the cleanup standards in Table E, near the surface of the water table and down to approximately
40-50 feet. As discussed earlier, VOCs have been found in the groundwater which do not meet the clean-
up standards at depths below the capture of the cwrent system.
If the water is discharged off-site to Adobe Creek it must be treated with the activated carbon
fIlter system at the facility. Alternatively, the water may be discharged to the city sewage treatment
facili ty.
The net present value cost for this alternative would be between $2.0 and $2.1 million. Capital
costs range from $48,400 to $54,400, and annual O&M costs range from $156,814 to $167,350.
ALTERNATIVE 14
Alternative #4 convens two deep monitoring wells into extraction wells that will be intermit-
tently pumped. This alternative would address the groundwater contamination, at concentrations which
do not meet the cleanup standards in Table E, beneath the zone of capture of the CUITent extraction system
and would rely on the continued operation of the extraction wells in the CWTent system to capture the
shallow contaminants. The time estimate to achieve clean-up standards is 25-30 years. The conversion
of deeper monitoring wells to extraction wells would prevent any funher migration of contaminants in
the deeper portion of the aquifer.
If the water is discharged off-site to Adobe Creek it must be treated with the activated carbon
filter system at the facility. Alternatively, the water may be discharged to the city sewage treatment
facility.
The net present value cost for this alternative is $2.6 to $2.8 million. Capital costs range from
$28,400 to $34,400, and annu4I O&M costs range from $158,858 to $168,650.
18
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AL TERNA TIVE #5
Alternative #5 is EPA's selected remedy. Alternative #5 combines the actions of Alternatives
#3 and #4. The two additional shallow extraction wells, in conjunction with the existing wells, will
reduce the estimated time required to restore the shallow groundwater to clean-up standards in 15-20
years. The conversion of two deep monitoring wells (LF-13 and LF-17) to extraction wells will pre-
vent any funher migration of contaminants in to the deeper portion of the aquifer.
If the water is discharged off-site to Adobe Creek it must be treated with the activated carbon
filter system at the facility. Alternatively. the water may be discharged to the city sewage treatment
facility .
The reduced estimated time to achieve the clean-up standards also reduces the number of years
of O&M. Because of the reduced length of O&M. the ultimate cost is less than alternatives #3 or #4.
The net present value cost of this alternative ranges between $2.1 to $2.2 million. Capital costs would
be $74.000, and annual O&M costs range from $160,388 to $169.350.
VID. SUMMARY OF COMPARATIVE ANALYSIS OF AL TERNA TIVES
The remedial alternatives developed in the FS were analyzed in detail using the nine evaluation
criteria required by the NCP. The resulting strengths and weaknesses of the alternatives were then
weighed to identify the alternative providing the best balance amoung the nine criteria. These criteria
are: I) overall protection of human health and the environment; 2) compliance with applicable or
relevant and appropriate requirements (ARARs); 3) reduction of toxicity. mobility. or volume through
treatment; 4) long-term effectiveness and permanence; 5) shon-term effectiveness; 6) implememabil-
ity; 7) cost; 8) state acceptance; and 9) community acceptance. The nine criteria and the relative
performance of the alternatives in relation to each criterion and each other is summarized below.
PROTECfION OF HUMAN HEALTH AND THE ENVIRONMENT
Overall protection of human health and the environment addresses whether 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.
As the no-action alternative (#1) does not achieve the cleanup standards it will no longer be
discussed. Alternatives #2 through #5 are equally protective of human health and the' environment by
eliminating or reducing the risk of exposure to contaminants in groundwater. Alternatives #2 through
#5 use engineering controls in the fonn of a groundwater extraction system to remove contaminated
groundwater from the aquifer where it could be used for consumption.
COMPLIANCE WI1H ARARS .
Pursuant to section 121(d)(l) of CERCLA. remedial actions must attain a degree of clean-up
which assures protection of human health and the environment. Additionally. remedial actions must
meet standards. requirements. limitations, or criteria that are "applicable or relevant and appropriate"
(ARARs). Federal ARARs for any site include requirements under any federal environmental laws.
19
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State ARARs include promulgated requirements under state environmental or facility-siting
laws that are more stringent than any Federal ARARs and have been identified to EP A by the state in
a timely manner. .
Applicable Iequirements are those clean-up standards. control standards. and other substantive
environmental protection requirements, criteria.. or limitations promulgated under Federal or State law
that specifically address a hazardous substance. pollutant, contaminant, remedial action. location or
other circumstance at a CERCLA site.
Relevant and appropriate requirements are defined as those cleanup standards of control and
other substantive environmental protection requirements. criteria. or limitations promulgated under
Federal or State law that, while not "applicable" to a hazardous substance. pollutant, contaminant.
remedial action. location or other circumstance at a CERCLA site. nevenheless address problems or
situations sufficiently similar to those encountered at the CERCLA site to indicate their use is well-suited
to the particular site. If no ARAR addresses a particular situation. or if an ARAR is insufficient to protect
human health or the environment. then non-promulgated standards. criteria. guidances. and advisories
(To Be Considered. or TBCs) must be used to provide a proteCtive remedy.
Additionally. response actions which take place off-site must comply with all laws. administra-
tive and substantive.
Types of ARARs
There are three types of ARARs. The first type includes "contaminant-specific" requirements.
These ARARs set limits on concentrations of specific hazardous substances. pollutants. and contami-
nants in the environment. Examples of this type of ARAR are ambient water quality criteria and drinking
water standards.
The second type of ARAR includes location-specific requirements that set restrictions on cenain
types of activities based on site characteristics. These include restrictions on activities in wetlands.
floodplains. and historic sites.
The third type of ARAR includes action-specific requirements. These are technology-based restrictions
which are triggered by the type of action under consideration. Examples of action-specific ARARs are
Resource Conservation and Recovery Act (RCRA) regulations for waste treatment, storage. and
disposal.
ARARs are identified on a site-specific basis from information about specific chemicals at the
site. specific features of the site location. and actions that are being considered as remedies.
The following section will outline the Applicable or Relevant and Appropriate Requirements
(ARARs) and other informatidn (TBCs) that EPA considered for this site.
CONTAMINANT-SPECIFIC ARARs and TBCs
Cleanup levels are set at health-based levels. reflecting current and. potential use and exposure.
For systemic (noncarcinogenic) toxicants. cleanup levels represent that amount to which humans could
20
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be exposed on a daily basis without unacceptable adverse effects occuning during their lifetime. For
carcinogens, cleanup levels must fall within a 10-4 to 1(4 risk range (NCP, 40 CFR ~300.430
(e)(2)(1 )(A)(2».
The contaminant-specific ARARs for the Sola site are Federal and State of California drinking
water standards. Each is relevant and appropriate to set as cleanup standards at the site. A list of Federal
and State drinking water standards are presented in Table E.
Federal Drinking Water Standards
. Section 1412 of the Safe Drinkin~ Water Act (SDW At 42 U.S.c. 6300~-1 "National Drinkini Water
Re~lations": National Primary Drinking Water Regulations. 40 CFR Part 141.
Potential drinking water regulations include Maximum Contaminant Levels (MCLs) for
specific contaminants. MCLs are enforceable standards which apply to specified contaminants which
EPA has determined have an adverse effect on human health. MCLs are set at levels that are protective
of human health and set close to Maximum Contaminant Level Goals (MCLGs).
Under the authority of the NCP (40 CFR ~300.430 (f)(5», MCLGs set at levels above zero must
be attained by remedial actions for ground or surface water that is currently or potentially a sources of
drinking water, where the MCLGs are relevant and appropriate under the circumstances based on the
factors in NCP (40 CFR ~300.400 (g)(2». All of the MCLGs which are applicable to the Sola site are
less sttingent than or equal to the federal MCLs.
Accordingly, the appropriate remedial standard for groundwater is the current federal or state-
MCL, whichever is most sttingent. Table E compares the current state and federal MCLs for the
chemicals of concern and identifies the cleanup standard.
State Drinking Water Standards
California Safe Drinkini Act. California Domestic Water Ouality Monitorin~ Re~lations. CAC Title
22 Division 4. Chl\Pter 15
California has promulgated MCLs for primary VOCs as shown in Table E. EP A has chosen the
California Mas for primary VOCs as the groundwater cleanup standard for the site where the
California MCLs, for YOCs, was more sttingent than federal Mas.
ACTION-SPECIFIC ARARs AND TBCs
Treatment by Carbon AdsoqJtion
Solid Waste Disposal Act. as amended by Resource Conservation and Recovery Act 42 U.S.C &6901
~.
Use of granular activated carbon (GAC) for remediation of VOCs can trigger requirements
associated with regeneration or disposal of the spent carbon. If the spent carbon is a listed waste or a
21
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characteristic waste, it is regulated as a hazardous waste under RCRA and California 's Hazardous Waste
Control Laws (CAC Title 22 ~67520-67525).
Containers used for storage of hazardous waste on site for more than 90 days must be:
Maintained in good condition (40 CPR ~264.171);
Compatible with other stored wastes (40 CPR ~264.172);
Closed during storage (40 CFR t264.173);
Inspected weekly (40 CPR U64.175);
Placed on a sloped, crack-free base with containment system in place capable of handling
10 percent of the free liquids stored (40 CPR t264.175);
Placed 50 feet from facility's property line if ignitable or reactive (40 CFR t264.176);
Separated by a dike or other barrier if incompatible wastes are stored near each other (40
CPR t264.177);
At closure, remove all hazardous wastes and residues from containment system (40 CPR
t264.178);
Storage of banned wastes must be in accordance with 40 CFR f268 (40 CFR ~268.50).
On-site storage of contaminated carbon may trigger substantive requirements under state laws
(Hazardous Waste Control Law, CACTitle 22 U67 I 80-67194 and CACt6724O-67248)and municipal
or county hazardous material ordinances. If the spent carbon is a hazardous waste, construction and
monitoring requirements for storage facilities may also apply.
LOCATION-SPECIFIC ARARs AND TBCs
A site characterization was conducted at Sola to determine whether special characteristics
existed at the site which warranted location specific requirements. No location-specific requirements
were found.
LONG-TERM EFFECTIVENESS AND PERMANENCE
Long-term effectiveness and permanence refers to the ability of a remedy to maintain reliable
protection of human health and the environment over time. This criterion includes the consideration of
residual risk and the adequacy and reliability of controls.
Remedial alternatives *2 through *5 all result in minimal residual risk. Once the contaminants
in groundwater have been reduced to the cleanup standard concentration the primary risk will have been
permanently reduced. With the exception of the no-action alternative, all of the alternatives are expected
to attain clean-up standards in groundwater, thereby resulting in minimal risk from residual contami-
nants in groundwater. However, the residual risk posed by the contaminants at their respective cleanup
Standards remains.
j
Extracted water will either be treated with the existing activated carbon f1lter system at the
facility and discharged off-site to Adobe Creek or discharged to the City sewage treatment system. In
both discharge options, adequate treatment would occur; either in the existing carbon f1lter system or
in the CitY sewage treatment sYStem ~
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REDUCTION OF TOXICITY. MOBll..ITY. OR VOLUME TIiROUGH TREATMENT
Reduction of toxicity, mobility, or volume through treatment refers to the preference for a
remedy that uses treattnent to reduce health hazards, contaminant migration, or the quantity of
contaminants at the site.
All of the alternatives, except the no-action alternative employ treatment. in varying degrees.
The discharge option employed will determine the type and location of treaanent; discharge to Adobe
Creek will require prior treatment with the carbon filter system; while discharge to the Petaluma sewage.
system will result in treattnent prior to or in the sewage treattnent system
Extracted water will either be treated with the existing activated carbon fllter system at the facility and
discharged off-site to Adobe Creek or discharged to the City sewage treatment system. The City of
Petaluma has an industrial discharge limit of 1 part per million (ppm) for total toxic organics.
Monitoring results from the extraCtion system indicate that concentrations in groundwater are presently
low enough to meet this standard without treatment
Each of the alternatives, except the no-action alternative, is expected to attain clean-up standards
in groundwater, thereby resulting in minimal risk from contaminant residuals in groundwater. Spent
carbon filters containing the contaminants will be managed in compliance with ARARs.
SHORT- TERM EFFECTIVENESS
Shon-term effectiveness refers to the period of time needed to complete the remedy and to any
adverse impacts on human health and the environment that may be posed during the construction and
implementation of the remedy.
Alternatives #2 through #5 are expected to pose no unacceptable shon-term risks to the
community or workers during construction and implementation. Installation of the extraction wells
could be completed in one to two weeks. .
Alternatives #3 or #5 are expected to attain clean-up standards in 15 - 20 years because of their
higher extraction volumes, pumping at approximately 35-40gpm. Alternatives #2' or #4 will pump
groundwater at an approximate rate 25- 30 gpm resulting in an increased time of 25 - 30 years to achieve
the cleanup standards in the aquifer. Alternative #2 will capture less contamin.ated groundwater than
other alternatives ('3 or #5) and it would leave deeper VOC-affected groundwater untreated and uncon-
trolled. Altemarlve'3 will capture a larger volume of contaminated shallow groundwater but it would
leave the deeper VOC-affected groundwater untreated and uncontrolled. Alternative #4 will reduce the
mobility of deeper VOC-affected groundwater by pumping contaminated monitoring wells but would
capture approximately the same volume of shallow groundwater as Alternative #2. Alternative #5 will
capture a larger volume of contaminated shallow groundwater and also decrease the mobility of deeper
VOC-affectcd groundwater. j
23
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IMPLEMENT ABILITY
Implementability refers to the technical and administrative feasibility of a remedy, including the
availability of materials and services needed to implement the selected remedy. It also includes
coordination of Federal, State and local governments in cleanup of the site.
All of the alternatives are implementable. The installation of extraction wells involves well
known and frequently used method and materials.
The carbon filter treatment system has a current capacity of 60gpm and will not have to be upgraded if
it is used. All alternatives require gJ'OUI!dwater monitoring.
am:
This criteria examines the estimated costs for each remedial alternative. For comparison, capital
costs and annual O&M costs are used to calculate a present wonh cost for each alternative.
Alternative #2 would not incur any additional capital cost and the annual O&M expenditure on
the system would be approximately $166,000. Alternative #2 has a total $2.7 million net present value
with treatment and discharge to the creek or $2.5 discharging to the sewage treatment system. The latter
has a lower net present value because of a slightly lower O&M COSL
Alternative #3 would have approximately $8,000 in capital costs plus an approximate annual
O&M cost of $153,000. The net present value for alternative #3 is $2.1 million if treatment occurs on-
site or $2.0 million if discharging to the sewage treatment system.
Alternative #4 would require an approximate capital cost of $46.000 and an approximate annual
O&M cost of $168,000. The total net present value is $2.8 million if treated in the carbon filter system
or $2.6 million if discharged to the sewage treatment system. .
Alternative #5 has a capital cost of approximately SI23.000 and an approximate annual O&M
cost of $169.000. The total net present value is. $2.2 million if treatment in the carbon filter system is
used or $2.1 million if discharging into the sewage treatment system.
STATE ACCEPTANCE
State acceptance indicates whether. based on its review of the RI. FS. and Proposed Plan, the state
in which the site resides agrees with the preferred alternative.
EPA has involved the SFRWQCB during the development of the RIlFS and selection of the
remedy. SFRWQCB. on behalf of the State of California, has stated a preference. and concurs with
EPA. on the selection of alte&ative #5 as the preferred remedy.
24
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COMMUNITY ACCEPTANCE
Community acceptance indicates the public suppon of a given alternative.
EP A solicited input from the community on the groundwater clean-up alternatives proposed for
the Sola Optical Site. The public did not oppose the preferred alternative. There was one wrinen set of
comments ~eived from one member of the community stating suppon for the preferred remedy. A
response to this set of comments is provided in Anachment B.
IX. SELECTED REMEDY
EP A has selected Alternative '5 as the remedy for the site. This remedy addresses groundwater
at the site and consists of:
groundwater monitoring to assure capture of contaminated groundwater and to demonstrate
restoration of groundwater to cleanup standards throughout the aquifer,
operation of existing extraction wells (8),
construction and operation of two (2) additional shallow extraction wells,
conversion of monitoring wells LF-13 and LF-17 to deep extraction wells,
construction and operation of additional piping for the new and convened wells,
on-site treatment and discharge off-site or discharge to the City of Petaluma sewage treatment
system.
The intent of this remedy is to restore groundwater to its beneficial use. which for this site is
drinking water. Based on infonnation obtained during the remedial investigation and on a careful
analysis of all remedial alternatives. EPA and the State of California believe that the selected remedy
will achieve this objective.
The selection of this remedy is based on a comparative analysis of the alternatives presented
above and provides the best balance of trade-offs with respect to the nine evaluation criteria. The
selected remedy provides the fastest route towards achieving the cleanup standards and restoring the
groundwater to full beneficial use.
The selected remedy includes groundwater extraction for an estimated period of 15 to 20 years.
This groundwater extraction system will operate until the cleanup standards are achieved and continu-
ously maintained throughout the aquifer. The cleanup standards are state or federally promulgated
drinking water standards. Until these standards are achieved and continuously maintained, EPA will
periodically re-evaluate the remedy every five years with the first evaluation in October 1993. At these
evaluations. if available EPA methodology is more accurate, the risks of soiVgroundwater gases
migrating through the soil into potential residences on the site will be re-evaluated.
.
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It may become apparent, during implementation or operation of the groundwater extraction
system, that contaminant levels have ceased to decline and are remaining constant at levels higher than
the cleanup standards. Based on the performance data, operation of the extraction system will be
adjusted as warranted if so determined during the periodic EP A evaluations. For example, it may be
appropriate to discontinue operation of extraction wells in areas where cleanup goals have been attained,
alternate pumping at wells to eliminate stagnation points, and pulse pump to allow aquifer equilibration
and encourage adsorbed contaminants to partition into groundwater for extraction.
Alternative #5 has a capital cost of approximately $123,000 and has an approximate annual
O&M cost of $ 169,000. The total net present value is $2.2 million if treatment in the carbon filter system
is used or $2.1 million if discharge is into the sewage treatment system.
x.
STATUTORY DETERMINATIONS
The selected remedy is protective of human health and the environment as required by section
121 of CER CLA. The selected remedial action, when complete, shall comply with applicable orrelevant
and appropriate environmental standards established under Federal and State environmental laws,
unless a statutory waiver is granted. The selected remedy is cost-effective, use permanent treatment
technologies or resource recovery technologies to the maximum extent practicable and includes
treatment as a principal element The following sections discuss how the selected remedy for the Sola
site meets these statutory requirements.
PROTEcrION OF HUMAN HEALTH AND THE ENVIRONMENT
Attainment of clean-up standards assures that the site risk falls within the acceptable range. -The
cumulative site risk of 10-4 falls within the acceptable range (10-4 to 10-6). Alternatives #5 uses
engineering controls in the form of a groundwater extraction system to remove contaminated ground.
water from the aquifer where it could be used for consumption. The extraction of VOC-contaminated
groundwater will significantly reduce the threat of exposure to residents. The implementation of this
remedy will not create any shorHerm risks nor any negative cross-media impacts.
ATTAINMENT OF ARARS
All ARARS would be met by the selected remedy. The selected remedy will achieve compliance
with chemical-specific ARARS by extracting groundwater with contaminant concentrations exceeding
. the chemical specific cleanup standards. Action-specific ARARS will be met by both discharge options.
There are no applicable location-specific ARARS.
COST -EFFECTIVENESS
EPA believes the selected remedy is cost-effective and extraCtS the contaminated groundwater
within a reasonable period of time. The selected remedy fulfills the nine criteria and provides overall
effectiveness in relation to its cost
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Alternative #5 has an capital cost of approximately $123,000 and an approximate annual O&M
cost of $169,000. The total net present value is $2.2 million if discharged to the creek or $2.1 million
if discharging into the sewage treattnent system.
USE OF PERMANENT SOLUTIONS AND AL TERNA TIVE TREATMENT TECHNOLOGIES OR
RESOURCE RECOVERY TECHNOLOGIES TO THE MAXIMUM EXTENT PRACI1CABLE
The selected remedy represents the maximum extent to which permanent solutions and treatment
technologies can be used in a cost-effective manner for the Sola site. Of those alternatives that are
protective of human health and the environment and comply with ARARS, EP A has determined that the
selected remedy provides the best balance: in long-term effectiveness and permanency; reduction of
toxicity, mobility and volume through treattnent; shon-term effectiveness; implementability, and cost
effectiveness; the selected remedy has also gained state and community acceptance.
PREFERENCE FOR TREATMENT AS A PRINCIPAL ELEMENT
VOC-contaminated groundwater will be extracted, and the VOCs will be treated. The treatment
will occur in the current on-site system using carbon adsorption to remove and concentrate the VOCs
or the treattnent will occur in the sewage treattnent system operated by the City ofPetaluma. Therefore,
this remedy satisfies the statutory preference forremedies that employ treatment which permanently and
significantly reduces toxicity, mobility, or volume of hazardous substances as a principal element
.
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