United Stap° ~
EnwensnenuJ Protection
agency
Office o(
Emergency and
Remedial Response
EPA/RODm09-eo/046
June 1990
Superfund
Record of Decision:
Watkins-Johnson (Stewart Division), CA
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50272-101
REPORT DOCUMENTATION 11. REPORTHO. 12.
PAGE EPA/ROD/R09-90/046
3. Aedplent8 ~on No.
SUPERFUND RECORD OF DECISION
Watkins-Johnson (Stewart Division), CA
.'.., ZI.,..t-~nn - Fin;:t1
5. AepoI1 Date
06/29/90
4. Title and Subtille
&.
7. Authorla)
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U.S. Environmental Protection
401 M Street, S.W.
Washington, D.C. 20460
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The Watkins-Johnson site is an active research and development, manufacturing, and
industrial complex in Santa Cruz County, five miles north of Santa Cruz, California.
The Watkins-Johnson Company has owned and operated the complex since 1963, conducting
such activities as: . metal machining, degreasing, metal plating, and photo laboratory
activities. During these activities, a variety of organics, inorganics and metals
were used. In 1984, Regional authorities found TCE and TCA in the Watkins-Johnson
wastewater disposal system. Further investigations revealed soil contamination at
the site and ground water contamination in the Santa Margarita aquifer underlying the
site. The aquifer has been designated a sole-source aquifer used for drinking water,
and is comprised of a perched zone and a regional zone. In addition, the aquifer is
easily accessible for drinking water supplies and for contamination from the ground
surface. The primary contaminants of concern affecting the soil and ground water are
VOCs including PCE and TCE, and metals including silver.
(See Attached Sheet)
17. Doc&8MntAn8Jy818 .. D88crIpIore
Record of Decision - Watkins-Johnson (Stewart Division), CA
First Remedial Action - Final
Contaminated Media: soil, qw
Key Contaminants: VOCs (PCE, TCE), metals (silver)
b. IdIn~T-
c.COSAn~
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EPA/ROD/R09/046
Watkins-Johnson, CA
First Remedial Action - Final
Abstract (Continued)
The selected remedial action for this site includes soil vapor (vacuum) extraction with
pretreatment of extracted vapors using GAC prior to ambient discharge; capping and
grading contaminated soil areas to minimize the potential for mobilization of soil
contaminants to the ground water; installing infiltration leach fields to prevent
offsite migration of ground water contaminants in the perched zone; installing gravity
drains to transfer the contaminated ground water from the perched zone to the regional
aquifer zone for subsequent extraction; ground water pumping and onsite treatment to
remove contamination from both the perched and regional zones using GAC adsorption with
offsite regeneration of spent carbon; discharge of treated water onsite for industrial
and consumptive use, offsite to surface water, and onsite to recharge the perched
zone; and ground water monitoring. The estimated present worth cost for this remedial
action is $2,156,243, which includes an estimated annual O&M cost of $167,820.
PERFORMANCE STANDARDS OR GOALS: Ground water treatment standards for both the perched
and regional zones were based on chemical-specific SDWA MCLGs or the more stringent of
SDWA MCLs or PMCLs and State MCLs, thereby achieving a residual risk of 10-4 to 1~.
Chemical-specific goals include PCE 0.005 mg/l (PMCL) and TCE 0.005 mg/l (MCL).
Soil remediation will ensure that soil no longer poses a threat to the ground water;
however, no chemical-specific goals have been set for the soil.
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.
RECORD OF DECISION
WATKINS-JOHNSON SUPERFUND SITE
SCOTTS VALLEY, CALIFORNIA
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,;
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.
RECORD OF DECISION
DECLARATION STATEMENT
SITE NAME AND LOCATION
Watkins-Johnson Superfund site
Scotts Valley, California
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected remedial action
for the Watkins-Johnson Superfund site located in Scotts Valley,
California, developed in accordance with the Comprehensive En-
vironmental Response, Compensation, and Liability Act of 1980, 42
U.S.C. 19601, (CERCLA) and, the National Oil and Hazardous Sub-
stances Pollution Contingency Plan, 40 C.F.R. Part 300, 55 Fed.
Reg. 8666 (NCP). This decision is based on the administrative
record for this site.
The State of California has no objection to the technical
aspect. of the selected remedy.
,
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 Record of Decision, may present an imminent and
substantial endangerment to public health, welfare, or the en-
vironment.
DESCRIPTION OF THE REMEDY
The selected remedy for the Watkins-Johnson site addresses
groundwater contamination, in which trichloroethylene is the
primary contaminant of concern. Other contaminants detected in
groundwater at concentrations exceeding the selected treatment
standards include vinyl chloride, tetrachloroethylene, 1,1-
dichloroethylene, 1,1-dichloroethane, 1,4-dichlorobenzene, cis-
1,2-dichloroethylene, and silver. The selected remedy also ad-
dresses an area of soil contaminated with volatile organic chemi-
cals including l,l-dichloroethylene, cis-l,2-dichloroethylene,
tetrachloroethylene, methylene chloride, l,l,l-trichloroethane,
l,1,2-t~ichloroethane, trichloroethylene and chloroform.
This action represents the final remedial action to remove
contaminants from groundwater and soil. Several response
measures were previously performed at the site by Watkins-
Johnson. The major components of the selected remedy will:
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Table of Contents
.
Paqe
Declaration
I. Site Description...................................... 1
II. site History and Enforcement Activities............... 2
III. Community Participation Activities.................... 3
IV. Scope and Role of Response Action..................... 4
V. Summary of Site Characteristics....................... 5
VI. Summary of Site Risks................................. 7
VII. Summary of Alternatives............................... 11
VIII. Comparison of Alternatives............................ 17
IX. The Selected Remedy................................... 19
X. Statutory Determinations.............................. 24
XI. Documentation of Significant Differences.............. 25
XII. Reservation of Record................................. 26
Attachments
Response Summary
List of Figures
Fiqure
1. Site Location Map
2. Hydrogeologic Cross-Sections
3. Detailed Site Map
4. Distribution of TCE in the Regional Aquifer, May 1987
5. Distribution of TCE in the Regional Aquifer, March 1989
List of Tables
Table
1. Concentration of Contaminants in Soil and Groundwater
2. Summary of Carcinogenic Risk at the Site
3. Summary of Non-carcinogenic Risk at the Site
4. Remedial Alternatives
5. Summary of Applicable or Relevant and Appropriate Require-
ments for the Site
6. Federal and State Groundwater Treatment Standards for the
site
7. Summary of Costs of Selected Remedy
8. Estimated Rates of Groundwater Pumping and Discharge
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DECISION SUMMARY
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I. SITE DESCRIPTION
The Watkins-Johnson Superf~nd site (the site) is located in
Santa Cruz County, approximately 5 miles north of the City of
Santa Cruz, in a small valley located west of the city of Scotts
Valley, east of Sky Park Airport, and southwest of the Santa Cruz
Mountains (Figure 1). This area is considered to be within the
California Coast Range and is in close proximity to California's
Pacific coastal zone.
The elevation at the Watkins-Johnson site is approximately
460 feet above mean sea ~evel (MSL). The area north of the site
is comprised of forested mountains that are incised by numerous
stream channels. Surface elevations within this mountainous area
range from 400 to 1,200 feet above MSL. The area south of the
site is comprised predominantly of rolling grassy hills with sur-
face elevations ranging from 560 to 800 feet above MSL.
Several creeks drain the region. These include Bean Creek, .
Carbonera Creek, Lockhart Gulch, Ruins Creek, and Zayante Creek. \
Bean Creek, a tributary to Zayante Creek, crosses north of the
site and roughly divides the major aquifer, the Santa Margarita,
into northern and southern portions. Both Zayante and Carbonera
Creeks drain into the San Lorenzo River, which is west of the
site. The San Lorenzo River flows southward and eventually
enters the Pacific Ocean at Monterey Bay.
The Santa Margarita aquifer which underlies the site, is a
major source of groundwater for the Camp Evers, Scotts Valley,
and Mission Springs areas. EPA designated the Santa Margarita
aquifer as a sole source aquifer, used for drinking water. In
the Scotts Valley area, the aquifer is unconfined, and the Santa
Margarita Formation crops out over much of the land surface. In
the immediate vicinity of the Watkins-Johnson site, the Santa
Margarita aquifer is comprised of a perched zone in addition to
the regional zone (Figure 2). The perched zone is elevated about
35 feet above the regional zone. The aquitard which supports the
perched groundwater and separates the two zones is a moderately
cemented conglomerate. The aquifer is accessible for development
of drinking water supplies and for contamination by chemicals
migrating from the ground surface.
1
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III. COMMUNITY PARTICIPATION ACTIVITIES
EPA has maintained three information repositories containing
the Communit, Relations Plan, RI/FS Reports, technical documents,
fact sheets, and other reference material. These repositories
are located at the Scotts Valley Branch of the Santa Cruz Public
Library, the Scotts Valley Wate~ District Office, and the Scotts
Valley Wastewater Division Office. In addition, the entire Ad-
ministrative Record is available at the Scotts valley Branch
. Library. The availability of these documents, as well as the an-
nouncement of a public comment period extending from February 14,
1990 until April 14, 1990 was published in the Santa Cruz Sen-
tinel on February " 1990 and in the Scotts Valley Banner on
February 14, 1990.
On February 28, 1990, EPA representatives briefed members of
the Scotts Valley Town Council on the Proposed Plan for remedia-
tion of the site. In addition, a public meeting was held on
March " 1990, at which EPA representatives presented the
Proposed Plan for the site and answered questions. A response to
comments received during the public comment period is included in
the Response Summary, which is part of this Record of Decision
(ROD) .
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WATKINS-JOHNSON
SITE MAP
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GAC WA7£'R
TREA Tl/ENT SYSIDI
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LEACH F7EJ.D
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A BUILDING 6
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. Groundwater Monitoring Wells
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fIGURE 3
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TCE is the major contaminant of concern in the perched
zone. The area consistently containing the highest
concentrations is near the former Building 6 dilution
tafik. TCE values analyzed from groundwater samples in
this area range from 34 to 13,000 ug/l. In addition to
TCE, 1,1-dichloroethylene (l,l-DCE) and vinyl chloride
are constituents of interest for the perched zone
(Table 1). Detection of 1,1-DCE in concentrations
equal to or greater than 2 ug/l was limited to test
wells on the edge of the TCE plume. Vinyl chloride was
detected in three wells in september 1988.
o
TCE was the major contaminant detected in the regional
zone together with lesser concentrations of 1,1,1-
trichloroethane (l,l,l-TCA), 1,2-DCE, and 1,1-DCE
(Table 1). The concentrations of TCE formed a narrow
cigar-shaped plume which extended to the northwest, to
Bean Creek in May 1987 (Figure 4). The highest con-
centrations of TCE were north of the Building 6 dilu-
tion tank area. Data collected since the initiation of
aquifer restoration indicate that the contaminant
plume, within the regional zone, has steadily
diminished and is now contained almost entirely within.
the plant area (Figure 5). \
Six private wells have been found north of the
Watkins-Johnson site that are considered potential
receptors. These wells are located downgradient. from
the site in the generally northward flow path of the
perched zone. However, not only has the TCE distribu-
tion, which is limited to the plant area, not changed
in extent over time, but the present aquifer restora-
tion control scheme is preventing northward flow of
contamination toward these wells.
o.
The aquifers in the Monterey and Lompico formations un-
derlie the contaminated Santa Margarita Formation.
There is an apparent upward gradient from the Lompico
to the Monterey, which indicates that the potential for
contaminants to flow from the Santa Margarita to the
Monterey or Lompico in the vicinity of the plume is
very small.
Bean Creek is directly connected to the perched zone
in the area upstream from Ruins Creek extending at
least to the point where treated water is discharged
to Bean Creek. Downstream from Ruins Creek, Bean Creek
is hydraulically connected to the regional aquifer.
Although contamination had previously been found in
Bean Creek, more recent sampling shows contamination is
below detection limits. .
6
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The third step of the Lisk assessment is the toxicity as-
sessment. Chemicals present at this site include both car-
cinogens and non-carcinogens. Three contaminants are of concern
based on their potential ability to cause cancer: TCE is a Group
B-2 agent, probable human carcinogen; 1,1-DCE is a Group C Agent,
possible human carcinogen; and vinyl chloride is a Group A Agent,
known human carcinogen. These classifications are based on the
strength of scientific evidence that these agents may be car-
cinogenic. For TCE, there is sufficient evidence of car-
cinogenicity in animals, and inadequate evidence that the com-
pound is carcinogenic in humans. For 1,1-DCE, there is only
limited evidence the compound is carcinogenic in animals and the
available evidence on humans is inadequate. For vinyl chloride,
there is sufficient evidence of carcinogenicity in animals and
humans. Cancer Potency Factors (CPFs) have been developed by the
EPA's Carcinogenic Assessment Group (CAG) for estimating excess
lifetime cancer risks associated with exposure to potentially
carcinogenic chemicals. CPFs, which are expressed in units of
mgjkg-day, are multiplied by the estimated intake of a potential
carcinogen in milligrams per kilogram per day (mgjkgjday) to
provide an upper-bound estimate of the excess lifetime cancer
risk associated with exposure at that intake level. The term
"upper-bound" reflects the conservative estimate of the risks .
calculated from the CPF. Use of this approach makes underestima- .
tion of the actual cancer risks highly unlikely. CPFs are
derived from the results of human epidemiological studies or
chronic animal bioassays to which animal-to-human extrapolation
and uncertainty factors have been applied.
Several non-carcinogenic chemicals have been identified to
be chemicals of concern at this site. Reference doses (RfDs)
have been developed by the EPA for indicating the potential for
adverse health effects from exposure to chemicals exhibiting
non-carcinogenic effects. The RfD is an estimate, with an uncer-
tainty of perhaps an order of magnitude, of a lifetime daily ex-
posure for the entire population (including sensitive in-
dividuals) that is expected to be without appreciable risk of
deleterious effects. Estimated intake of chemicals from environ-
mental media (e.g., the amount of a chemical ingested from con-
taminated drinking water) can be compared to RfDs. RfDs are
derived from human epidemiological studies or animal studies to
which uncertainty factors have been applied (e.g., to account for
the use of animal data to predict effect on humans). These un-
certainty factors help ensure that the RFDs will not underes-
timate the potential for adverse non-carcinogenic effects to oc-
cur.
The last step in the risk assessment process is the risk
characterization. At this point the information from the
proceeding steps is combined to determine if an excess health
risk is present a~ the site. Excess lifetime cancer risks are
determined by multiplying the intake level with the cancer
potency factors. These risks are probabilities that are-6
generally expressed in scientific notaiion (e.g., 1 X 10 ). An
excess lifetime cancer risk of.1 X 10- indicates that, as a
plausible upper-bound, an individual has a one in one millio~
8
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tial endangerment to wildlife in the vicinity of the site which
might occur due to contamination of Bean Creek. Based on the
more recent rounds of surface water sampling, no contaminant con-
centrations ~ave been detected in Bean Creek. Furthermore, the
ongoing aquifer restoration begun in October 1986 has sig-
nificantly reduced the extent of the groundwater contaminant
plume so that it no longer intercepts or threatens to intercept
Bean Creek.
There is no evidence, based on the survey, that any fish or
wildlife trust resources inhabit the property. The industrial
nature of the property and extensive coverage of soil by build-
ings and pavement prevent potential exposure of migratory birds
to contaminated soil. The failure to detect volatile organic
compounds in Bean Creek downstream of where the groundwater in-
tercepts the creek suggests that aquatic life in the creek is not
presently at risk from site-related contaminants.
10
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perched zone gravity drains plus the Building 8 leachfield,
gravity drains plus Building 8, 2, and 6 1eachfie1ds and the Test
Well (existing well to be used for extraction), and gravity
drains plus Building 8, 2, and 6 1eachfie1ds and soil flushing at
the former Building 6 dilution tank.
Groundwater Extraction: This technology uses a combination
of existing and new extraction wells to create a cone of depres-
sion to capture and remove the contaminant plume from the
regional aquifer. Groundwater extraction from the perched zone
has been shown to be difficult due to the local hydraulic charac-
teristics and dewatering problems. There is currently one
perched zone extraction well on-site that is operated intermit-
tently and is considered a part of this option.
No Action: The no-action option represents a baseline
against which the other alternatives are compared. No effective
remedial strategies would be implemented in either the perched or
regional zones. Existing gravity drains would be plugged, in-
filtration through the existing 1eachfie1d would be discontinued,
and existing extraction wells would be abandoned. Contaminated
groundwater would be allowed to migrate off-site and into Bean
Creek.
Perched zone groundwater would migrate northward, leaking
into the regional zone and eventually discharging into Bean
Creek. This option provides no mitigation of existing risks, and
would allow other areas to be impacted. These conditions would
persist indefinitely until the contaminant plume had been
diluted, completely discharged, or reduced by natural biological
and chemical processes.
Groundwater Treatment
Several processes have been evaluated to remove chlorinated
hydrocarbons from extracted groundwater consistent with the ex-
isting National Pollution Discharge Elimination System (NPDES)
permit and as a requirement for discharge in conjunction with
other disposal methods. The treatment technologies described
below include granular activated carbon (GAC) adsorption, air
stripping, and ultra violet (UV) oxidation. The no-action option
is also summarized.
Granular Activated Carbon (GAC) Adsorction: This technology
uses large volumes of GAC to filter contaminated groundwater.
The filtration bed would be replaced with fresh GAC as necessary
for the effective removal of contaminants; the spent GAC would be
regenerated off-site. The current GAC treatment system on-site
consists of two pressurized vessels each containing 20,000 pounds
of GAC. The units are operated in a continuous mode with
groundwater pumped directly into the distribution system at 20
pounds per square inch gauge (psig).
GAC is very effective in removing chlorinated hydrocarbons
from water provided that the carbon is replaced periodically.
The existing system has been shown to treat groundwater down to
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Treated Water End Use
Watkins-Johnson currently uses treated groundwater in three
ways: on-si~e industrial and drinking water, off-site discharge
to Bean Creek, and recharge to the perched zone. Concern has
been raised that the water currently discharged to Bean Creek
could be used as an off-site drinking water supply to offset ex-
isting groundwater pumpage. At this time, we estimate that only
25 gallons per minute of treated groundwater will be discharged
to Bean Creek; this is the estimated minimum flow necessary to
maintain the habitat and support aquatic life. If the estimated
volume of the discharge to Bean Creek should increase sig-
nificantly, EPA may consider designating other uses for the
treated effluent. Such a change may be reflected in an Explana-
tion of Significant Difference or other appropriate document. A
change in the designated use of the treated effluent may include
the off-site domestic use of treated groundwater in conjunction
with the Creek discharge. The discharge to Bean Creek is an
off-site discharge for which Watkins-Johnson must continue to ob-
tain all appropriate permits, including an NPDES permit from the
Regional Board, and comply with a1~ applicable State and federal
laws. .
Source Control
The Risk Assessment prepared for this site indicates that
existing soi1 contamination poses no significant risk to human
health or the environment through direct contact. However,
direct exposure may occur as a result of on-site excavation. In
addition, existing contamination continues to threaten
groundwater quality. contamination has not been identified
within the uppermost fifteen feet of soil. Most areas of
detected soil contamination are beneath asphalt caps which sig-
nificantly reduce the downward mobility of the residuals. The
highest concentrations of soil contamination are in the area of
the former Building 6 dilution tank. The detailed analysis
evaluated four source control options. These were treatment by
vapor extraction, by soil flushing, stabilization by capping and
grading, and the no action option. A source control option(s)
will be required to treat soils to a level that no longer
presents a threat to the groundwater.
Soil VaDor Extraction: This technology uses a suction to
remove organic contaminants from the soil matrix. A vacuum is
applied to a dry well screened in the contaminated vadose zone.
The vacuum applied is sufficient to cause residual contaminants
to partition from the soil matrix into the soil gas and be
evacuated from the well. Soil vapor may be treated at the sur-
face to remove organic constituents prior to ambient discharge.
A pilot system operated at the site of the former Building 6
dilution tank indicated that soil vapor extraction is capable of
removing small quantities of residual soil contamination. Ef-
fluent from the pilot system contained such small quantities of
contaminants that health-based risk from this source would be
negligible. However, a full-scale vapor extraction operation
14
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groundwater from both the perched and regional zones; GAC adsorp-
tion to treat the extracted groundwater; soil vapor extraction to
remove VOCs from the soil; capping and grading to minimize the
potential foe mobilization of soil contaminants to the
groundwater; and on-site industrial and consumptive use of
treated water, off-site discharge to Bean Creek, and on-site
recharge to the perched zone.
The capital cost for this alternative is estimated to be
$837,738; the annual operation and maintenance cost (O&M) is es-
timated to be $167,820. The present worth of this alternative is
estimated to be $2,156,243.
Alternative 2: This alternative includes the use of leach-
fields to control movement of the perched zone contaminant plume;
gravity drainage to transfer perched zone contamination to the
regional zone; groundwater extraction to remove contaminated
groundwater from both the perched and regional zones; air strip-
ping to treat the extracted groundwater with GAC adsorption to
treat air emissions; soil vapor extraction to remove VOCs from
the soil; capping and grading to minimize the potential for mobi-
lization of soil contaminants to the groundwater; and on-site in-
dustrial and consumptive use of treated water, off-site discharge
to Bean Creek, and on-site recharge to the perched zone. \
The capital cost for this alternative is estimated to be
$611,938; the annual operation and maintenance cost (O&M) is es-
timated to be $167,820. The present worth of this alternative is
estimated to be $1,930,443.
Alternative 3: This alternative includes the use of leach-
fields to control movement of the perched zone contaminant plume;
gravity drainage to transfer perched zone contamination to the
regional zone; groundwater extraction to remove contaminated
groundwater from both the perched and regional zones; UV oxida-
tion to treat the extracted groundwater; soil vapor extraction to
remove VOCs from the soil; capping and grading to minimize the
potential for mobilization of soil contaminants to the
groundwater; and on-site industrial and consumptive use of
treated water, off-site discharge to Bean Creek, and on-site
recharge to the perched zone.
The capital cost for this alternative is estimated to be
$703,938; the annual operation and maintenance cost (O&M) is es-
timated to be $139,000. The present worth of this alternative is
estimated to be $1,796,171.
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Reduction of Toxicity, MobiJitv, or Volume Throuqh Treatment
All three alternatives use treatment to permanently and sig-
nificantly r~duce the toxicity, mobility or volume of con-
taminants in both the soil and groundwater. Therefore, all three
satisfy the statutory preference for remedies utilizing as a
principal element treatment that significantly reduces the
toxicity, mobility or volume of the hazardous substance.
Short Term Effectiveness
Alternative 1 performs best under this criterion because it
poses the least risk to human health and the environment during
implementation. Although Alternative 3 has the potential to be
equally effective in the short term, no data is currently avail-
able to indicate whether implementation would pose any risk to
human health and the environment. Alternative 2, using treatment
by air stripping and GAC adsorption, has the potential for posing
impacts to human health and the environment during implementa-
tion. While air stripping is capable of treating to nondetec-
table levels and permanently destroying the removed contaminants,
a large influent contaminant concentration could exceed the
design capacity of the stripper, allowing effluent discharges in
excess of the treatment standards. All the remedial alternatives
will achieve their remediation goals within similar time frames.
ImDlementabilitv
The three alternatives perform equally under this criterion.
The administrative and technical feasibility of each of the al-
ternatives is comparable.
Cost
Alternative 3 is the least costly alternative.
1 is the most costly alternative.
Alternative
State AcceDtance
It is believed that the state would accept any of the three
alternatives evaluated.
Community AcceDtance
It is believed that the community would accept any of the
three alternatives evaluated.
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In the case of zinc, the only number available was the
Secondary federal MCL, and this number was selected as the treat-
ment standard. For several chemicals (1,2-dichlorobenzene, cad-
mium and lead), only proposed MCLs or MCLGs exist, and these
values were chosen as treatment. standards. In the case where no
federal MCLGs, federal MCLs or state MCLs are promulgated or
proposed, then the State Action Level or Applied Action Level was
selected as the treatment standard. This was the case for 1,1-
dichloroethane. In the case of nickel, the only value available
was an EPA Health Advisory, and this value was selected as the
treatment standard. In the case of vanadium, no values were
identified for selection as treatment standards. However, this
chemical was only detected in 1 of 21 perched zone samples and 2
of 32 regional zone samples, and was, thus, eliminated from fur-
ther consideration.
The following compounds were detected in groundwater at con-
centrations exceeding their selected treatment standards:
trichloroethylene, vinyl chloride, tetrachloroethylene, 1,1-
dichloroethylene, 1,1-dichloroethane, 1,4-dichlorobenzene, cis-
1,2-dichloroethylene and silver. Treatment to the specified
stand~~ds will result in a residual risk within the range of 10-4
to 10 .
\
Health-based ARARs pertaining to soil contamination are not
available for the site. The soil contamination will be
remediated to a level that no longer poses a threat to the
groundwater. This alternative also complies with the Monterey
Bay Unified Air.Pollution control District (MBUAPCD) Rule 1000
which is applicable to any air emissions associated with this
remedial action.
The land disposal restrictions of Subtitle C of the Resource
Conservation and recovery Act (RCRA) are not ARAR for this
remedial action. The treatment technoloqy used in this alterna-
tive will treat the contaminated groundwater to nondetectable
levels. Once the groundwater is so treated, it no longer con-
tains hazardous waste and no longer is subject to regulation un-
der Subtitle C of RCRA.
Technical Asnects of the Selected Remedy
The selected remedy for the site involves several com-
ponents, including containment and removal of contaminated
groundwater within the perched and regional zones, treatment of
extracted groundwater, and implementation of limited source con-
trol measures. The costs for the selected remedy are summarized
in Table 8. .
At several points during the discussion of the selected
remedy, specific remedial designs are referenced including the
number and general location of gravity drains, extraction wells,
and leachfields: the pumping rates of extraction wells: the dis-
charge rate from the GAC system; the method of discharge from the
GAC system: etc. EPA recognizes that specific engineering
20
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tures a major portion of th~ regional zone contaminant plume.
The well on the airport property will be used to capture any por-
tion of the contaminant plume that migrates beyond the influences
of the on-si~e extraction wells. Groundwater quality monitoring
will be necessary to ensure that contaminant levels remain below
the treatment standards and to evaluate the progress of the
remedy. It is estimated that this system will require 8 years to
reach the treatment standards in the regional zone.
The total pumping rate for the four extraction wells during
the fourth quarter of 1989 was 209 gallons per minute (gpm):
however, the total projected pumping rate is estimated to be 110
gpm. The pumping rate is likely to change during the remedial
action process. Once the regional zone contaminant plume con-
centrations have reached the treatment standards, the extraction
wells will be shut down. This will result in the dissipation of
the cone of depression and a return to natural flow conditions.
continued groundwater quality monitoring on at least a quarterly
basis will occur to ensure that contaminant levels remain below
the treatment standards. The specific details of the groundwater
monitoring program and the long term O&M requirements will be
determined during the RD/RA phases.
Contaminated groundwater removed by the 5 extraction wells i
will be treated using a GAC adsorption system. This system is
already on site and operating.
The on-site GAC system treats contaminant concentrations to
non-detectable levels. Effluent from the GAC system is dis-
charged in three manners: on-site use at the Watkins-Johnson
plant, on-site recharge through leachfields to maintain the
perched zone groundwater mounds, and off-site discharge to Bean
Creek. Discharge to Bean Creek is an off-site activity: there-
fore, Watkins-Johnson must comply with all applicable laws and
obtain all applicable permits for this discharge.
Table 8 indicates the current (based on fourth quarter 1989
data) and projected water use rates for effluent from the GAC
system. Discharge to Bean Creek is considered a beneficial use
of a relatively minimal amount of water. This water assists in
maintaining flow within Bean Creek, thereby protecting the as-
sociated natural habitat.
Based on the Risk Assessment, there is no significant risk
posed to human health or the environment by leaving currently
documented, residual soil contamination in place. However, by
using source control measures and preventing further release of
contaminants from soil to groundwater, the overall time for the
groundwater remedy will be reduced. This will be accomplished
through soil vapor extraction and capping and grading.
Using this
screened in the
plied vacuum is
tition from the
method, a vacuum is applied to a dry well
contaminated portion of the vadose zone. The ap-
sufficient to cause residual contaminants to par-
soil matrix into the soil gas and be evacuated
22
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X. STATUTORY DETERMINATIONS
The selected remedial action is protective of human health
and the enviconment. For each pathway of exposure at the site,
the remedy eliminates, reduces or controls the riski posed. The
overall site risk will be reduced to within the 10- to 10-6
range for carcinogens and the Hazard Indices for non-carcinogens
will be less than one. Implementation of the remedy will cause
no unacceptable short-term risks or cross-media impacts.
The selected remedial action complies with all federal and
state ARARs. These ARARs are listed on Tables 5 and 6, attached
to and incorporated herein by reference.
The selected remedial action is cost-effective. The overall
effectiveness of the selected remedial action is proportional to
its cost, in that it represents a reasonable value for the money
to be spent.
As discussed in the Comparison of Alternatives Section of
this ROD, the selected remedy utilizes permanent solutions and
alternative treatment technologies or resource recovery tech-
nologies to the maximum extent practicable. The selected remedy.
provides the best balance of tradeoffs among the alternatives ~
with respect to the evaluation criteria, especially the five
balancing criteria. The selected remedy was superior to the
other alternatives under the long-term effectiveness and per-
manence and short-term effectiveness criteria. All the remedial
alternatives evaluated in the remedy selection process were ac-
ceptable to the State and the community.
The selected remedial action satisfies the statutory
preference for selecting remedies in which treatment that per-
manently and significantly reduces the volume, toxicity or
mobility of the hazardous substances, pollutants and contaminants
is a principal element. The remedial action uses treatment to
address the contaminated groundwater, which is the principal
threat posed by the site. GAC adsorption will remove volatile
organic chemicals from the groundwater and will achieve a per-
manent and significant reduction of the toxicity, mobility or
volume of the contaminants. Similarly, vacuum extraction fol-
lowed by vapor-phase GAC adsorption will remove volatile organic
chemicals from contaminated soil, thereby also meeting the
statutory preference.
24
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XII. RESERVATION OF RECORD
The precise identification of long-term operation and main-
tenance act~ities and the use of engineering and institutional
controls, the details of an ongoing groundwater monitoring
program, and the costs of each of these activities will be iden-
tified during the RD/RA phase for the site.
26
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RESPONSE SUMMARY
The Pro~osed Plan for the Watkins-Johnson site was issued to
the public and announced that the public comment period would ex-
tend from February 14, 1990 through April 14, 1990. The Proposed
Plan described EPA's preferred remedial alternatives for con-
taminated groundwater and soil at the site. On February 28,
1990, EPA briefed members of the Scotts Valley Town Council on
the Proposed Plan, and on March 7, 1990 EPA presented the
Proposed Plan at the public meeting.
SUMMARY OF COMMENTS RECEIVED
During the public comment period, EPA received only two let-
ters regarding the Proposed Plan for the site. One comment let-
ter, dated February 28, 1990 was provided by a group of residents
from a local condominium mobile home park, and second comment
letter, dated April 13, 1990, was provided by the Watkins-Johnson
Company. The Chairman of the Board of Directors for the same
residents group also provided verbal comment during the public
meeting. EPA received written comments on the proposed remedy
from the California Department of Health Services and the Centra~
Coast Region of the California Regional Water Quality Control \
Board. The substantive comments and EPA's responses are sum-
marized below.
Residents GrOUD Comment:
The residents group requested access to that effluent from
the on-site GAC system which is currently being discharged to
Bean Creek, in order to help to help satisfy their water supply
needs. Based on their calculations, the group estimated that
with access to this water they could cut back their demands on
the Santa Margarita aquifer, thereby saving approximately 280
aclft per year. The group pointed out that the transfer of this
water was a relatively simple matter and that the distance in-
. volved was less than 100 yards.
EPA ReSDonse:
SPA considered, but rejected at this ~ime, ~he residents'
proposed option of allowinq ~he ~reated effluent ~o be used as a
public wa~er supply source rather ~han discharqinq ~he ~reated
effluent into Bean Creek. The residents' calculations were based
on a discharqe rate of 187 qpm from the on-site GAC system to
Bean Creek. Bowever, the current discharqe rate ~o Bean Creek is
157 gpm, and the projected discharqe rate i. estimated to be 25
qpm. Based on the projected discharqe rate ~o Bean Creek, BPA
has determined that continued discharqe to Bean Creek is a
beneficial use of this .ater, .s it .ssists in aaintaininq flow
within the Creek, thereby protecting the .ssociatea natural
habitat. In the event ~hat the actual discharge ~o Bean Creek
significantly exceeas the estimatea 25 qpm rate, BPA may consiaer
changing the designatea methoa of aisposal of ~he treated ef~
27
-------
"This section of the ROD remedy selection should
mention that some changes may be made to the remedy as a
result ~f the the remedial design and construction
process. The ROD should include a clear statement that
such changes in general, reflect modifications resulting
from the engineering design process."
EPA ResDonsel
EPA acknowledges the comment and has incorporated it into
the "Selected Remedy" .ection of the ROD. 'lhe Selected Remedy
specifies requirements regarding gravity drains and extractions
wells; however, provisions have been included in the event that
engineering modifications are required during RD/RA.
4. WJ pointed out that recent computer modeling indicates that
the rate of groundwater extraction and the rate of discharge from
the GAC system can be decreased, while still allowing for effec-
tive containment of the contaminant plume.
EPA ReSDonse:
EPA has revised the "Selected Remedy" section of the ROD to \
clarify that engineering details such as the rate of groundwater
extraction and discharge may be determined during the RD/RA.
5. WJ pointed out that the exposed area of residual soil con-
tamination which the Proposed Plan requires to be capped, has al-
ready been capped. Therefore, WJ felt that this section of the
Proposed Plan was no longer required.
EPA ReSDonse:
BPA has addressed this change in sit. condition in the
"Documentation of Siqnificant Chang.s" ..ction of the ROD. Al-
though the cap component of the preferred alternative identified
in the Proposed Plan has b.en complet.d, the remedy selected in
this ROD maintains a cap as a component of the remedial action.
The ROD incorporates 1:he cap component to ensure that the cap is
maintained a8 part of the remedial action.
6. WJ proposed groundwater treatment standards consisting of
MCLs at the property line with a goal of five times the MCL in-
side the property line or until a zero slope occurs on the
groundwater concentration vs. time graph for a period of one
year. WJ supported this comment with the following statement
taken from an October 18, 1989 memorandum from Jonathan Z. Can-
non, OSWER Acting Assistant Administrator:
"In many cases it may not be possible to determine
the ultimate concentration reductions achievable in the
groundwater until the groundwater extraction system has
been implemented and monitored for some period of time.
29
-------
"Here Watkins-Johnson has already spent over
$50,000 on vapor extraction. This effort was cost-
effective at the outset -- eight kilograms of con-
taminan~ mass were extracted in the first few weeks.
However, after that, the effectiveness of the remedy
dropped off quickly, to the point where only 20 grams
per day were being removed. Therefore, the incremental
costs of removing the remaining mass will be proportion-
ally high compared with the effectiveness of the
process. Unless EPA identifies a soil cleanup goal, it
is not possible to perform the cost-effectiveness
analysis that the NCP requires. Because EPA has already
concluded that seil contamination presents no health
hazards, EPA should follow its guidance document en-
titled "Determining Soil Response Action Levels Based on
Potential Contaminant Migration to Groundwater,"
EPA/540/2-89/057/, Oct. 1989."
EPA ReSDonse:
On Kay 8, 1990 representatives from WJ, BPA and DBS met to
discuss the issue of whether 8011 vapor extraction is needed as
part of the remedial .C~iOD at the site. WJ representatives
presented evidence to document that vapor extraction was no
longer necessary. EPA and DBS representatives both agreed,
however, that existing information is not adequate to document
that contamination in the vadose 80ne is Dot a continuing source
of contamination of the groundwater. Therefore, BPA has selected
a remedial action that includes soil vapor extraction as a com-
ponent. Bowever, WJ may provide technical information to EPA
during the remedial design stage to show that vapor extraction is
no longer necessary. EPA will consider such information and
decide whether any change of a component of the selected remedial
action is warranted. Such a change would be reflected in an Ex-
planation of Significant Differences or other appropriate docu-
ment.
\
EPA can provide WJ with a numerical 80del developed to ap-
proximate the leaching of soil contaminants to the groundwater.
This 80del .ay be calibrated aDd used with .ite-.pecific data to
aid in determining when residual .oil contamination no longer
poses a threat to groundwater.
California Regional Water Quality Control Board,
Central Coast Reaion (The Reaional Board} Comments:
1. The Regional Board submitted comments to EPA strongly object-
ing to any change to the remedial action allowing a cleanup stan-
dard less stringent than State or federal drinking water stan-
dards. The Regional B08rd referred to the Cleanup and Abatement
Order it issued to WJ in 1986 which required the company to at-
tain approximately one-half the level of the present MCLs. The
Regional Board urged a conservative approach in establishing
cleanup levels due to the aquifer's designation as a sole source
aquifer.
31
-------
3. DHS commented that the California Environmental Quality Act
(CEQA) should be included as an ARAR for the WJ site.
.
EPA ResDonse:
EPA has determined that the requirements of CEQA are no more
strinqent than the requirements for environmental review under
CERCLA, as amended by SARA. Pursuant to the provisions of
CERCLA, the NCP and other federal requirements, BPA's prescribed
procedures for evaluation of environmental impacts, selectinq a
remedial action with feasible mitiqation measures, and providinq
for public review, are designed to ensure that the proposed ac-
tion provides for the short-term and lonq-term protection of the
environment and public health and hence perform the same function
as and are substantially parallel to the State's requirements un-
der CEQA.
Since EPA has found that CERCLA, the NCP, and other federal
requirements are no less strinqent than the requirements of CEQA,
EPA has determined th~t CEQA is not an ARAR for this site.
EPA will continue to cooperate with DHS and other State and
federal aqencies durinq the desiqn phase of the remedial action i
to clarify further environmental review and mitiqation require-
ments and ensure that they are fulfilled.
33
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-------
.
i
Tlbt. J \
I
I
Summary or Estimated Noncarcinogenic Risk
at Watkins-Jobnson Site (Maximally Exposed Individual)l
Exposed
Population Route Medium Subchronic Chronic
.
Adult Residenrs Ingestion around Wiler 0.036 0.249
(Well in Perched Ingestion SoU 0.000 0.000
Zone)1 Dermal SoU ~ Q.Wl
Total' 0.039 0.252
\
Child Residents Ingestion Ground Wasa 0.063 0.435
(Well in Perched Ingestion Soil 0.009 0.011
Zone) Dennal SoU ~ ~
Total 0.078 0.452
Adult Worker Ingestion around Wasa 0.018 0.134
(Well in Perched Ingestion Soil 0.001 0.002
Zone) Dermal SoU gmz 0Jm
Total 0.021 0.138
Adult Residenrs Ingestion around War 0.041 0.245
(Well in Regional Ingestion Soil 0.002 0.002
Zone)' Denna1 SoU DJm. ~
Total 0.044 0.248
Child Residems Inpaioa Gmund Wifei' 0.0'72 0.428
(Wel in Regional Ingeslion SoU 0.009 0.011
Zone) Denna1 Soil QJDi QJDi
ToW 0.087 0.445
Adult Worker Ingesdon Ground Water 0.021 0.149
(WeD in Regional Ingeaion Soil 0.001 0.002
Zone) Dennal SoU DJm QJm
ToW 0.Q24 0.153
1 Bued on the upper.bound concenera6on ClQnwa.
2 Based on a hypothetical drinkinl water weD in &he perdted IDftL
3 All rOUIa. mediL
~ Bued on a hypotheticaJ drinkinl water weD in the nponal zane.
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.
Table 5
APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS
FOR THE WATKINS-JOHNSON SITE
Standard, Requirement,
Criteria. or Limitation
DescriDtion
Federal:
Safe Drinking Water Act
Use of MCLs and MCLGs
as treatment standards for
current or potential
drinking water source.
See Table 6.
State:
Air Resources Act
Establishes allowable dis- \
charge standards for point
sources within each air pollu-
tion control district, and Am-
bient air Quality Standards.
Establishes state
authority to clean up
hazardous substance releases
and compensate person injured
by hazardous substances: es-
tablishes state "Superfund".
Hazardous Substances Account
Act/Hazardous Substances
Cleanup Bond Act
California Safe Drinking
Water Act
Regulations and standards
for public water systems: sets
Maximum Contaminant Levels
(HCLs) and Secondary MCLs
(SHCLs) which are enforceable
in California: requirements
for water quality analyses and
laboratories.
porter-Cologne Water Quality
Control Act
Establishes authority for
State and Regional Water
Boards to determine site-
specific discharge require-
ments and to regulate disposal
of waste to land.
1
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labl(' 6
FEDERAL AND STATE GROUNDYATER ARARS AND TREATMENT STANDARDS
YATKINS-JOHNSON SUPERFUND SITE
(expressed in milligrams per liter)
Max halll Federal Federal CA-DHS CA-DHS DHS Appl i ed Treatment
Chemical Detection ~1 MCl1 MCl Action level Action level Standard
Organics 0.1003
ChlorofoMII 0.007 0.006 0.100 .
1,2-Dichlorobenzene 0.004 0.6002 0.6002 0.130 0.600
1,4-Dichlorobenzene* 0.008 0.015 0.015 0.005 0.005
1,1.Dichloroethane* 0.010 0.005 0.005
1,1-Oichloroethylene* 0.011 0.001 0.007 0.006 0.006
cis.1,2.dichloroethylene* 0.053 0.0702 0.0702 0.006 0.016 0.006
Methylene Chloride 0 0.005 0.040 0.005
Tetrachloroethylene* 0.029 0 0.0052 0.005 0.004 0.005
1,1,1.Trichloroethane 0.043 0.200 0.200 0.200 0.200
1,1,2.Trichloroethane 0.003 0.032 0.100 0.032
Trichloroethylene* 0.550 0 0.005 0.005 0.005 0.005
Vinyl Chloride* 0.006 0 0.002 0.0005 0.0005
Metals 0.0502
Arsenic 0.017 0.050 0.050
Sarhlll 0.140 5.0002 5.0002 1.000 1.000
Cachi l1li 0.0048 0.0052 0.0052 0.005
Chrcnillll 0.023 0.050 0.050 0.050 0.050
Copper 0.027 1.300 1.300 1.300
Lead 0.001 02 0.0052 0.005
Mercury 0.0002 0.0022 0.0022 0.002
Nickel 0.069 0.1005
SH ver* 0.061 0.050 0.050 0.050
V8n8di l1li 0.013
Zinc 1.700 5.0004 5.000
NOTES:
* . MaxillUl detection exceeded the treatment goal.
1 . Safe Drinking Yater Act (~), 42 U.S.C. Section 3OO(f)
2 . Proposed value (CFR Vol. 54, No. 97, p. 22064, May 22, 1989).
3 . Drinking water ~al ity standard for total trihalomethanes.
4 . Secondary Federal MCl.
5 . EPA Health Advisory.
6 -. Proposed value, State of Cal i fomia.
u. No value available.
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.
TABLE 8
WATKINS-JOHNSON WATER OSE RATES
Fourth Quarter 1989
t'OTAL GPH EXTRaCTED
!'eTAL UK Donn o.-aID
TOTAL GPH REINJECTED.
TOTAL GPK DISCHARGED TO CREEK
. REINJECTING INTO ONE LEACHFIELD
POTORE PROJECTED DATA
TOTAL GPK EXTRACTED
TOTAL GPK REOSED ON-SITE
TOTAL GPH REINJECTED.
TOTAL GPK DISCHARGED TO CREBK
. REINJECTING INTO '1'HREE LBACBPIELD8 15 an
aPK = Gallon. per Xinute
101
37 or 18\
15 or 7\
157 or 75\
\
110
37 or 34\
45 or 42'
25 or 24'
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