United States
Environmental Protection
Agency
Office of
Emergency and
Remedial Response
EPA/ROD R09-84/004
May 1984
SEPA
Superfund
Record of Decision:
San Gabriel/Area I Site, CA
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TECHNICAL REPORT DATA t
(Please read Instructions on the re~'erse before completing)
1. REPORT NO. 12. 3. RECIPIENT'S ACCESSION NO.
EPA/ROD/R09-84/004
4. TITLE AND SUBTITLE 5. REPORT DATE
SUPERFUND RECORD OF DECISION: 05/11/84
San Gabriel Area 1, CA 6. PERFORMING ORGANIZATION CODe
7. AUTHORCSI 8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM eLEMENT NO.
1,. CONTRACT IGRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS 13. Type OF REPORT AND PERIOD COVERED
Final ROD ReDort
U.S. Environmental Protection Agency 14. SPONSORING AGENCY CODE
401 M Street, S.W.
Washington, D.C. 20460 800/00
15. SUPPLEMENTARY NOTES
16. ABSTRACT
The San Gabriel Area I site is affected by one of four contaminated ground water
plumes affecting the San Gabriel ground water basin, approximately 40 miles east of
Los Angeles. Testing of wells by the California Department of Health Services (DOHS)
found areas of the basin contaminated with trichloroethylene (TCE), tetrachloroethyl~
(PCE), and other chlorinated hydrocarbons. The DOHS has set Action Levels for TCE
and PCE at the EPA suggested no adverse response level (SNARL) of 5 ppb and 4 ppb,
respectively. The three mutual water companies whose wells have been affected by the
contamination serve a population of approximately 200,000.
The selected initial remedial measure (IRM) is installation of an air stripping
system to treat contaminated ground water from the affected water mutual wells. The
capital cost for the project is $525,000 and annual O&M is estimated to be $38,000.
Key Words: Ground Water Contamination, Environmental Standard, Initial Remedial
Measure, Risk Level, SNARL, Air Quality, Air Permi t, Carbon Adsorp-
tion, Air Stripping, Data Adequacy, Trend Analysis
17. KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS b.IDENTIFIERS/OPEN ENDED TERMS C. COSATI field/Group
Record of Decision
San Gabriel Area I, CA
Contaminated media: gw
Key contaminants: solvents, TCE, PCE
18. DISTRIBUTION STATEMENT 19. SECURITY CLASS (Tllis Reporr) 21. NO. OF PAGES
None 64
20. SECURITY CLASS (This page) 22. PRICE
None
EPA F- 2220-1 (R.... 4-77)
PREVIOUS EDITION IS 08S0LETE
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16. ABSTRACT
Include a brief (200 I4IOrds 0' less) factual summary of the most sil!nitkant Informaliun ~'onlaln~'" III 110.. ,,'purl. II Ih.. "."",. . 11,,1;1111' a
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17. KEY WORDS AND DOCUMENT ANALYSIS
(a) DESCRIPTORS - Select from the Thesaurus of Enginecrir.j! and S..ientitk Tefl"' the proper aulhll,.,,'d I~'rlll' thai Idenufy th~' majur
concept of the research and are sufficiently specific and precise to be used a, index entrics for ....talo!!lnj:.
(b) IDENTIFIERS AND OPEN-ENDED TERMS - Use identifiers for projcct nam". code namc'. e"lulpment d"'Ij:nalors, ,'I... U\C "I'cn-
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endeavor, or type of physi.:al object. The application(s) will be cross-referenced with ..c,'ondar)! I .drm 1110-1 (R.... A~77) (R....ru)
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ROD ISSUES ABSTRACT
Site:
San Gabriel Area 1, California
Region:
IX
AA, OSWER
Briefing Date:
March 14, 1984
SITE DESCRITION
The San Gabriel Area I site is affected by one of four contaminated
ground water plumes affecting the San Gabriel ground water basin,
approximately 40 miles east of Los Angeles. Testing of wells by the
California Department of Health Services (DOHS) found areas of the
basin contaminated with trichloroethylene (TCE), tetrachloroethylene
(PCE), and other chlorinated hydrocarbons. The DOHS has set Action
Levels for TCE and PCE at the EPA suggested no adverse response level
(SNARL) of 5 ppb and 4 ppb, respectively. The three mutual water
companies whose wells have been affected by the contamination serve a
population of approximately 200,000.
Selected Alternative
The selected initial remedial measure (IRM) is installation of ~
air stripping system to treat contaminated ground water from the
affected water mutual wells. The capital cost for the project is
$525,000 and annual O&M is estimated to be $38,000.
ISSUES AND RESOLUTIONS.
1.
SNARL'S can be appropriately utilized as
guides for deciding if an IRM should be
conducted. They can also be used as an
aid to establish cleanup levels. SNARL'S
at 10-6 risk are acceptable goals.
lRM alternatives should be developed
to meet the 10-6 level if they are cost
effective. If this level can not be
achieved, a higher risk level might be
necessary.
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KEY WORDS
. Ground Water
Contamination
. Environmental
Standard
. Initial Remedial
Measure
. Risk Level
. SNARL
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3.
4.
.'
San Gabriel Area 1, California
March 14, 1984
Continued
ISSUES AND RESOLUTIONS
2.
Releases of ground water contaminants
(i.e., organic solvents) to the atmosphere
as a result of remedial technologies such
as air-stripping should be evaluated to
ensure that a public health threat is not
being transferred from one media to another.
A permit is not required for these air re-
leases under current EPA pOlicy. However,
technical requirements of the air program
should be followed. Although the site was
in a non-attainment area, air emissions from
this facility do not pose a public health
threat locally and do not measurably
contribute to area-wide air contamination.
The lowest cost alternative for this site
was dismissed from further consideration
because nearby water companies were not
willing to lease water rights from the
affected mutuals. The second lowest cost
alternative was also dismissed because
it involved dissolution of the water
mutuals. Of the remaining alternatives,
water treatment by air stripping was the
most cost-effective alternative.
Two of the water mutuals supported a
carbon adsorption treatment alternative.
One mutual indicated a preference for
carbon adsorption treatment and the other
was already treating water with a carbon
adsorption system. It was determined that
the operating carbon adsorption system was
underdesigned and it would be considerably
more expensive to upgrade than to install
an air-stripping system.
EPA has decided that the extra cost for
the carbon adsorption system was not
justified since the air stripping
alternative is negligibly less effective.
ROD briefings should contain the most recent
and historical data (e.g. analytical) so
that contaminant migration and contamina-
tion levels can be analyzed.
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KEY WORDS
. Air Quality
. Air Permit
. Carbon
Adsorption
. Air Stripping
. Data Adequacy
. Trend Analysis
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RECDID OF DECISIOO
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Initial Remedial Measure Alternative Selection
SITE :
San Gabri~l Area 1, £1 "=>nte, California
~ REVI~'
I have reviewed the following documents describing the analysis of
cost-effectiveness of Initial Remedial Measure alternatives for the
San Gabriel Area 1 Site:
- Study entitled "Draft Focused Feasibility Study, San Gabriel, San
Gabriel Basin, IDs Angeles County, California, December 6, 1983. n
- Staff summaries and recommendations, including the Record of Decision
Briefing Paper and the Summary of Initial Remedial Measure Alternative
Selection.
- CH2M Hill's analysis of the Hemlock Mutual Water ~y's carbon
~sorption system.
- Public Participation Responsiveness Summary.
DESCRIPI'ION OF SELECTP..D INITIAL ~IAL MEASURES
- Installation of three i~ividual packed tower air-stripping treatment
systems for the Richwood, Rurban Ibnes, and Hemlock Mutual Water
Carpanies.
DECIAMTICNS
Consistent wit.~ the Canprehensive Environmental Resp:>nse, Canpensation,
and Liability Act of 1980 (CERCIA), and the Natiooal Oil and Hazardous
Substances Contingency Plan (40 CFR Part 300), I have determined that th~
installation of water treatment systems for the Richwood, Ruman fbnes,
arXt Hemlock Mutual Water CaTlpanies at the San Gabriel Area 1 Site is a
feasible and cost-effective remedy necessary to limit exposure or threat of
exposure to significant health or enviroomental hazard. In addition, the
action will require future operation and maintenance activities to ensure
the continued effectiveness of the remedy. Those activities will be
considered part of the approved action and eligible for Trust FuOO DDnies
for. a period of one year after start of operation.
I have also determined that the action being ta.1cen is 6Wr.opI"iate
when balanced against the availability of Trust Fund JlDnies for use at
other sites.
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In addition to this action, EPA and the State will conduct a long-term
remedial investigation and feasibility study to identify the appropriate
remedy to the area-wide ground water contamination. I will make a future
determination ex>nceming any additional remedial actions following canpletion
of that study. -
J...LW':--
Judith E. Ayres
..few' Regiooal Administrator
EPA Region IX
5. n.st(
Date
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StJMMt\RY OF INITIAL REMEDIAL MFASURE ALTERNATIVE SELECI'IOO
SAN G\BRIEL AREA 1 SITE
EL foI:NI'E, CALIFORNIA
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SITE ux:ATIOO AND DESCRIPl'ICN
'!he San Gabriel Area 1 site is one of four plumes of ground water
contamination that have been found in the San Gabriel groW1d water basin.
'!his ground water basin is located within the San Gabriel Valley in the
oorthern part of IDs Angeles County, California. '!he valley is bounded to
the north by the San Gabriel M:>untains. A series of low (500 feet)
hills-the San Rafael, Repetto, Merced, Puente, and san Jose Hills-form the
western, southwestern, southern, and southeastern boundaries of the valley.
The major land uses in the valley are residential and cammercial/light
industrial.
San Gabriel Area 1 site is a oortheast to southwest trending plume of
ground water contamination approximately 4 miles long and 1 1/2 miles wide.
It is located along the axis of the Rio Hondo and Salt Pit Washes, and
parallels the San Gabriel River to the east. It lies primarily beneath the
cities of El M:>nte and M:>n~ia.
'!he San Gabriel Valley receives approximately 15-20 inches of annual
~ecipitation. Surfaoe water drains southward through the valley through the
Whittier Narrows, a 1.5-mile wide syncline between the Merced and Puente Hills.
The San Gabriel ground water basin that underlies the valley is a major
source of grouOO water. The depth of the ground water varies widely fran
approximately 25 to 300 feet below the surface, depending on the location
within the basin. The major ground water flow in the basin originates in the
Santa Fe Flood Control Basin ~rea and generally follows the southward pattern
of surface drainage in the valley toward the Whittier Narrows. '!he San Gabriel
basin has been heavily developed over the years, resulting in considerable
change to the patterns of ground water JlDVement. Water rights in the basin
were a1judicated in 1954. Forty-six water purveyors operate in the basin and
provide drinkiD; water for an estimated 700,000-1,000,000 people, as well as
water for industrial uses. The basin's water supply is replenished through
controlled recharge areas.
Large areas of the San Gabriel basin have been found to be contaminated
wi th chlorinated hydrocarbons. This contamination was first observed in
December 1979, when scnples taken by Aerojet Electrosystems Canpany in Azusa,
California were found to contain 1800 parts per billion (PIX» of trichloro-
ethylene ('OCE). Subsequent testiD; of nearby wells by the California Department
of He~th Services (IX>HS) fOlmd -~ contamination in 3 cdditional wells..An
extensive well-water testiB; program was begun by OOHS which f0urx3 large
areas of the basin contaminated with ~, tetrach1oroet.~ylene (PCE), and
other chlorinated hydrocarbons.
Based on existiD; water quality data fran the OOHS testing program,
it appears there are several distinct plumes of contamination in the basin.
San Gabriel Area 1 is the site of CX1e of these plumes. The ground water in
this plume has been found to contain PeE, ~, and carbon tetrachloride.
Many of the public wells in this area are contsninatec1 with levels of PeE
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aOO 'la: that exceed the EPA Suggested N:J Adverse Respnse levels (~).
[Note: the SNARL level referred to throughout this sunmary is based on a
lifetime risk of contracting cancer of 10=-6]. 'ltle water purveyors whose
wells have been affected by this cx>ntamination serve a population of
approximately 200,000. Cities and public water companies in the area have
been directed by IXRS to oonduct at least ronthly tests of their- wells to
ensure that their water supplies are safe for hlJrT\an conslJlTlPtion. IX>HS has
set Action levels for '1a: and PCE at the EPA SNARL levels (S aOO 4 pP>,
respectively). If alternative methods of reducing PCE cud 'OCE concentrations
below the Action levels (such as blending waters fran different wells) are
not effective, wells must be renDVed fran service.
Currently, there are three mutual water caupanies-Richwood, Rurban Ibnes,
am Hemlock-that have no alternative water supply and have been prcwiding their
custaners with water that is contaminated with PCE at concentrations above the
DCRS Action level. At present, no other organics have been fouOO at levels
above the IXIIS action limits in the mutuals' wells. Mutual water canpanies
are cooperatively owned water canpanies: in other words, the custaners own
shares in the carrpany.
SITE HIS'IORY
In 1980, the State of California conducted an extensive well water testing
program in the San Gabriel basin. ~t of 246 wells tested, 37 were found to
have 'la: concentrations greater than the Action level of S ppb. During this
same period, the IDs Angeles Regional Water Q.1ality Control Board (~)
conducted a survey of 233 industries for the purpose of obtaining information
regarding past and present 'Ia: usage. 'ltle results indicated that a minimlJlTl of
28 industries used and ex>ntinued to use or store 'ICE. Due to the oc:mplex nature
of the area's hydrogeology and the plume configuration, no specific source of
the contamination cx>uld be identified. 'ltle study concluded that the problem
resulted fran industrial practices 1S to 30 years ago, and that there was
little likelihood that current industrial use was making a major contribution
to the problem. 'ltle study did, however, reamnend sane industries for flJrt.."ler
investigation. When the IIQ:B report was released on April 2S, 1980, the State
announced its plan, described above, requiring periodic testing of wells to
ensure that public water supplies do not contain concentrations of 'ICE or PeE
above the EPA SNARL levels.
'ltle San Gabriel site was ranked 13th on the priority list for the State
Superfund program. On January 27, 1983, the State requested EPA assistance
in addressing the problem of ground water contamination in the San Gabriel
basin. On February 28, EPA Region IX suDnitted this site for inclusion on
the National Priorities List (NPL). For purposes of scx>ring with the Hazard
Ranking System (RRS), the San Gabriel area was separated into 4 separate
sites based upon the estimated location of the major plumes of ground water
contamination. 'n1e four areas were included in the proposed update to the
NPL-issued September a, 1983. On May 1, 1984, the EPA Administrator signed
the notice of rulemaking placing the San Gabriel sites on the final NPL.
Although they were soared separately, the sites will be CDIIbined for the
purpose of investigating and managing the overall ground water contamination
problem in the San Gabriel basin.
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In May 1983, a management committee oamprised of various local and State
agencies, EPA, and representatives of various water companies and public interest
organizations was established with California {XES as its chair. '!he objective!il
of this ccmnittee were: 1) to find a solution for the three mutual water
oarpanies that have a well contamination problem and no alternative water
supply; 2) to identify and control any 'Ia:/PCE sources; and 3) to develop an
overall strategy for management of the plumes. .
Since the first objective was the JlDst urgent of all three, the State
requested that EPA conduct a focused feasibility study (FFS) to evaluate
alternative water supplies for the three mutuals. '!he initial remedial
measures reccrrmended in this Record-of-Decision are based on the results of
the FFS. '1b acnd goal, EPA has initiated the source
investigation activities described in the enforcement section below. As a
first step toward meetiD; the third goal, EPA' s contractor, CH2M Hill, has
prepared a draft Remedial Action Master Plan (RAMP) to guide further action
concerniD; these areas. '!he first draft of the RAMP was oampleted in October
1983. CH2M Hill is presently redrafting the RAMP based on EPA' s ccmnents on
the draft. EPA will use the final RAMP as the basis for developing the Sc:upe
of Work, for a Remedial Investigation/Feasibility Study (RI/FS) of the O\1erall
ground water contamination problem in the san Gabriel Valley.
SITE STA'IUS
Of all the water purveyors in the basin, only the three mutual water
canpanies mentioned above (located in San Gabriel Area 1) are currently unable
to supply water that has contamination lev~ls below the EPA SNARL levels, du~
to lack of any al ternati ve water supply. Consequently, EPA and the State
have identified a ~ for initial remedial measures (IRM) to assist these
water purveyors in mitigating their water contamination problem.
Richwood Mutual Water ~y serves awroximately 204 households with
water frc:m two wells. PCE was first detected in October 1980, and since that
time has been found in concentrations ranging fran 12 to 92 ppb, greatly
exceeding the SNARL level if 4 ppb.' '!he rrost current data show PCE levels of
62 PIX> for Well No. 1 (6/1/83) and 92 ppb for Well No. 2 (5/17/83). In
addition to a PCE contamination problem, Richwood suffers fran potential
bacteriological problems and a severely deteriorated distribution system.
Well No. 2 was temtX>rarily taken out of service in May 1983, so that
bacteriological ~lems could be el~inated by chlorination.
Hemlock Mutual Water Canpany owns two wells and provides water to
approximately 199 households. PCE was first detected in May 1982. '!he fiouth
Well was taken out of service in 1982, on the order of the IDs Angeles County
Department of Health Services (IACDHS) when a PCE level of 184 ppb was
detected. '!he latest test results showed PCE levels of 50 ppb in the South
Well (12/14/82) and 38 ppb in the M:>rth Well (4/12/83). Hemlock has considered
using an activated carbon treatment system to lower PCE levels. Pilot tests
of the system were performed fran February through April 1983; the tests
showed that PCE will be rerrcved. Hemlock has bought the system fran a vendor,
but it is not yet in operation. At EPA's Region IX's request, CH2M Hill
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reviewed the design of the Hemlock c~rbon filter system; their analysis
conclud~ that the systE!l\ was underdesigned am did not include a margin of
safety normally included in these systems. '!his analysis will be disCUSsed
in a later section of this document.
Rurban Ibnes Mutual Water Canpany serves approximately 290 ~ households with
water fran bIO wells. PCE was detected first in October 1980. '!he latest
sampling data (5/17/83) showed PCE concentrations of 1.7 and 3.7 ppb for Wells
No. 1 and 2, respectively. In the past, however, PCE ooncentrations have ranged
as high as 16 ppb for Well No. 1 and 54 ppb for Well No.2. '!his latest
sampling is the first time the PCE ooncentration in both wells has been lower
than 4 PIX> since contanination was detected. ft)wever, results of sampling
over time have shown significant fluctuations that do not indicate either an
increasing or decreasing trend and the average concentration of PCE has
remain~ above the IXIiS action level. '!here fore , the recent sampling cannot
be considered sufficient evidence that the PCE SNARL level has been and will
continue to be met in the near future. Because these two contaminated wells
are Rurban' s only water supply, EPA and the State have determined that a
solution to Rurban's contamination problem should also be included in initial
remedial measures for San Gabriel Area 1.
ENroRCEMENl'
At the request of EPA Region IX, the Field Inspection Team (FIT) prepared
a list of potentially responsible parties (PRP's) in the San Gabriel basin,
for use in preparing RCRA Section 3007/CERClA Section 104 letters. '!his
list was based on the results of the 1980 ~ investigation, cited above,
whi~, identified several industries as warranting further investigation, and
a review of records and the history of developnent in the San Gabriel basin.
EPA Region IX sent 16 section 3007/104 letters to PRP's on August 19,
1983, bas~ on an initial list provided by FIT. '!his initial list was based
primarily on the 1980 ~B study which focused on San Gabriel Area 2.
Consequently, only two of these initial 16 PRP's are located in the San Gabriel
Area 1. After FIT provided its final list of PRP's, Region IX sent 72 additional
s~ion 3007/104 letters to PRP's in the San Gabriel basin on January 12, 19~4;
31 of these PRP' s were located in San Gabriel Area 1.
Region IX staff are in the process of reviewing the responses to these
3007/104 letters as they are received. Facilities which show a high potential
for having caused ground water contamination will be referred to FIT for site
inspections. Four of the 16 PRP's on FIT's initial list have already been
referred for inspections; howewr, none of these facilities is located in San
Gabriel Area 1. As a result, lIdministrative orders canoot be used to canpel
implementation of the IRM at this time, because evidence linking specific
responsible parties to ground water contamination in San Gabriel Area 1 has not
yet be;en produced.
. EPA Region IX will conduct a source investigation of the San Gabriel
basin. As part of that effort, FIT has prepared a source investigation
1«>rkplan. '!he source investigation will be closely coordinated with the
RI/FS for the San Gabriel basin to allow maximum utilization of ground water
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J1Dnitoring wells and sampling. In addition, respx1Sible parties identified
through the source irwestigation may assume responsibility for hydrogeologic
investigations (through the issuance of unilateral or consent administrative
orders) in their area of contanination.
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Since 00 resp:>nsible parties have been identified yet in san Gabriel
Area 1, it is recxrrmended that the Trust Fund be used to finance initial
remedial measures at the San Gabriel Area 1 site. Inmediate action must be
taken to provide an uncontaminated water source for residents of El Monte
served by the three mutual water canpanies. If parties responsible for
contamination of the mutual water arnpanies' wells are identified through
the source investigation, a cost recovery action can be taken to recover
Trust Fund ncnies used for the implementation of initial remedial measures
in San Gabriel Area 1.
AL'I'ERNATIVES EVALUATlOO
Purpose and CJ:>jective
'!he purpose of the IRM is to develop an alternative water supply or a
treat.TTent system that will enable the three mutual water canpanies described
above-Richwood, Rurban fbnes, and Hemloc.1c-to supply drinkin; water with levels
of PCE contamination below the EPA SNARL level of 4 ppb.
'!tie public healt.~ objective for the IRot is to ensur~ that all residents
affected by ground water contamination in San Gabriel Area 1 are provided
wit.~ a drinking water supply that is bP.low the EPA SNARL level for PCE-4
ppb. '!tIis level is based on a cancer risk level of 10-6, (i.e., that a
person exposed to this level of contamination in drinking water throughout
his or her lifetime (70 years) will bear a risk of less than or equal to 1
in 1,000,000 of contra~ing cancer as a result of ingesting PCE). '!he IRM
for San Gabriel ~ea 1 will ensure that this objectiv~ is met during the
interim period before a long-range solution to ground water contamination in
the ~an Gabriel basin can be implemented. During implementation of the IRM,
a remedial investigation and feasibility study (RIfFS) will begin to determin~
the appropriate long-term solution. '!tie long-term solution, howev~r, is not
expected to be in place until five years fran row due to the canplex techoological
issues associated with area-wide ground wat~r contamination.
Alternatives Considered
The follO'fling IRM alternative!; were CXX\sidered in the Focused Feasibility
Study (FFS) conducted by CH2M Hill:
Alternativ~ A - No Action
A1t~rnative B - Drill Deeper Wells
Alternative C - Provide Bottled Water
Al ternati ve D - Join With Another Water System
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Alternative E - Obtain Water Fran a Nearby Purveyor
Alternative F - Connect to the Metropolitan Water District~
Alternative G - Use Hane Treatment Devices
Alternative H - Treat Well Discharge With Carbon Adsorption System
Alternative 1 - Treat Well Discharge Wi~~ Air-Stripping System
Each of these alternatives would be designed so as to comply with other
appropriate environmental laws.
Initial Screening of Alternatives
The first step in screening the alternatives listed above was deletion
fran consideration of those alternati-.res not technically feasible or not likely
to effectively mitigate and min~ize the threat of harm to public health.
Alternative A--no action was el~nated because it would not mitigate the
public health threat described aOOve. Residents served by the three mutual
water companies are presently drinking water that is contaminated with PCE at
levels significantly above the EPA SNARL level of 4 ppb. Because of the
health threat resulting fran the no-action alternative, it was dropped fran
further consideration.
Alternative B--drilling existing ~lls deeper or drilling new wells to
find uncontaminated water was also el~inated. 'n1e distribution of contamination
in the ~ifer has not yet been def ined, so that the discovery of unoontaminated
water cannot be ensured. Even if an uncontaminated water supply is found, the
length of time it would remain uncontaminated is unknown. 'n'lerefore, this
alternative was not considered feasible or reliable to l~it exposure or
threat of extX>surking. Water would be delivered directly to hanes in five gallon bottles.
It was estimated that bottled water would be provided during th
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-7-
Alternative E~tain Water Fran A Nearby Purveyor - Mutuals would obtain
water While maintaining their water rights. This could be accomplished in
tw:> ways:
-
1 . MJtuals maintain water rights: A nearby purveyor provides water to
the mutuals and purchases replenishment water to replace the ground
water rem:>ved in excess of its adjudicated allotment.
2. Mutuals lease water rights: A nearby purveyor provides water to the
nutuals and the mutuals transfer or lease their water rights to the
p..lrveyor to increase its ground water allotment to cover the needs of
the mutuals.
Alternative F--connect to the Metropolitan Water District (~) - Build
a two mile pipeline and storage reservoir to connect the mutuals to the MWD
Middle Feeder (surface water) pipeline.
Alternative G--Use Home Treatment Devices - Install a carbon filter on
the ki td1en tap of each household.
Alternative H--Treat the Well Discharge With Carbon Adsorption System -
Install a carbon filter system at each well to filter the water as it is
p.mtped from the ground.
Alternative I--Treat the well Discharge With Air-Stripping System -
Install an air-stripping tower system at each well to treat the water as it
is plItped fran the ground. '!be contaminants would volatilize fran t."'e water
and be emitted to the air from the tower. -
'!be effectiveness of these alternatives in meeting the objective of the
IRrt was evaluated based on seven criteria:
1. Time - What is the cm:>unt of time needed to implement the alternative?
2. Reliability of Equipment - how reliable would the alternative be based
on the operating characteristics of the machinery involved?
3. Operational Complexity - how difficult would it be to operate the
alternative?
4. Pecnanence - how canpatible would the alternative be with potential
ultimate remedies for the area?
5. Institutional Canplexity - how difficult would it be to implement
the alternative from an administrative standpoint? How many parties,
. permits, and approvals would be needed to implement the alternative?
- 6. Carmuni ty Impact - what changes in the notmal way of life of the
mutuals' members w:>uld be caused by the alternative?
7. Risk of Failure - what is the effectiveness of the alternative in
protecting public heal t.~?
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Each alternative was evaluated using these criteria. Criteria were given
weighting factors to reflect the relative significance of each in the evaluation.
Criterion No. 7--risk of failure--was given the highest weighting factor
(5) since it directly evaluates the effectiveness of the alternative in
protecting p..lblic health, i.e., meeting the objective of the :mH.
The criteria were used to conduct a relative evaluation of each alternative.
The results of the effectiveness evaluation are shown in Table 1. As a result
of this evaluation, alternative G-use of heme treatment devices-was eliminated
fran further consideration. It scored low in the effectiveness evaluation
because of the maintenance required to replace the filter, the chance that a
slug of highly contaminated water could get ~ugh the filter or exhaust
the filter prior to the next change, low permanence, and the high risk of
failure.
All of the other alternatives had approximately the same effectiveness
evaluation scores, and were, therefore, determined to be equally effective in
meet ing the goal of the IR-1.
Cost estimates were developed for each of the remaining alternatives; a
summary of these estimates is given in Table 2. The costs listed in this table
have been calculated in 1983 dollars. Annual costs have been discounted at a
rate of 10 percent. Total 5-year costs are presented because the alternative
being selected is for use as an IRM and is oot considered the long-term remedy
for the site. It is expected that within that time period, a final remedial
alternative for the overall ground water contamination problem in the
$an Gabriel basin will be in place.
Two types of annual costs are presented for each alternative: operation
am maintenance (O&M) costs and/or increased water costs. O&M costs include
the costs to cover carbon changes, power, and maintenance requirements for the
treatment alternatives, maintaining pipelines, or providing bottled water.
Increased water costs are the increase in the cost of water for the different
alternatives over what the mutuals r shareholders are presently paying.
Recatrnendation of the Feasibility Study
Since each of the remaining alternatives was determined to be equally
effective in mitigating and minimizing the threat of harm to public health, the
selection of the oost-effective alternative was based on oost. The three
lowest-oost alternatives and their costs are summarized in the following table:
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1-
AL'reRNATIVE
CAPITAL
cnsTS
S-YFAR
O&M
rosTS
5-YEAR
INCREASED
WA'reR COSTS
$401,000 .
'IOrAL
5-YEAR
CCSTS
E. 2. Obtain Water Fran
a Nearby Purveyor;
Mutuals Lease
Water Rights
$51,000
$452,000
I.
Join With Another
Water Systen
Treat Well Discharge
With Air-Stripping
Systen
$190,000
$316,000
$506,000
D.
$525,000
$157,000
$682,000
The lowest-cost alternative was alternative E.2.--obtain water from a
nearby purveyor, mutuals lease water rights. 'Ibis al ternati ve was not
reccmnended by the fOC"Used feas ibil i ty report, however, because nearby water
purveyors indicated that they ~uld not be willing to provide water to the
IIIItuals under this option (as well as alternative £.1.).
Alternative Ir-join with another water system-was the second lowest-cost
alternative. The San Gabriel Valley Water Canpany has been identified as the
logical water canpany tor the mutuals to join. The San Gabriel Valley Water
Canpany has indicated that it ~uld be willing to provide water umer this.
. alternative. In exchange for the mutuals' water rights, the San Gabriel Valley"
Water Canpany ~uld replace and uwrade the mutuals' water del i very systems.
This alternative, which ~uld require dissolution of the mutuals, was not
reccmnended in the focused feasibility study report because at the time the
report was prepared, sufficient information did not exist to determine whether
the mutuals ~uld be willil'¥3 to disSolve. Although oot recxmnended in the
focused feasibility study report because of the Imcertainty of the mutuals'
interest, EPA informed the mutuals that this alternative was a viable option
for consideration.
Alternative I-treab'nent of well discharge with an air-stripping system-
was the third lowest-cost alternative. It is by far the lowest cost alternative
when alternatives £.2 and D are excluded (for the reasons cited above).
Alternative I's cost is less than half that of the next lowest cost alternative
that could be implemented-treatment of well discharge with a carbon adsorption
system.
Therefore, because all of these alternatives have been judged to be equally
effecti."e in meeting the objective of the 11M, Alternative I-treatment of well
discharge wi~~ an air-stripping system was recxmnended by the fOC"Used feasibility
study report as the DDSt cost-effective alternative.
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Analysis of Hemlock Water Mutual CaTpany' s Carbon Adsorption System
nIriD3 preparation of the focused feasibility study, EPA was notified
that Hemlock Mutual Water Canpany had purchased a carbon adsorption system
fran the Downey WeldiD3 and Manufacturing Canpany, Inc. At the request of
EPA Region IX, CH2M Hill reviewed the design of this system based on details
regarding the system prcwided by Downey WeldiD3. CH2M Hill's analysis of
this system determined that its capacity was \mdedesigned, and that the
system does not provide the margin of safety normally built into treatment
systems of this type. In addition, the need for a margin of safety is greater
in this situation, because the Hemlock Mutual Water Carpany's well water has
not been fully characterized.
1b upgrade Hemlock' s carbon system to the recoomended capacity based u{X)n
accepted engineering design criteria would require the installation of two
additional carbon vessels each with a c;ontact volume of 150 cubic f~t. It is
estimated that the design and installation of these supplemental vessels would
cost a!=Pl"Oximately $210,000, which is considerably JlDre expensive than
installing an air-stripping system at Hemlock.
a:»roNIfi REIATlOOS
Selection of an IFfo1 for San Gabriel Area 1 is different fran other typical
Superfund remedial actions in that implementation of any alternative requires
formal approval by the affected mutua.l water caupanies through a shareholders'
vote. Camnmity relations is always im{X)rtant at Superfund sites, but in this
case, where there is a need for formal approval by the affected "CCJTlTlunity",
it takes on added imp::>rtance.
'!be final draft "Focused Feasibility Study, San Gabriel," was made
available to the public on December 13, 1983. COpies of the report were
distributed to California OOHS, the San Gabriel Management and Technical
Advisory Conrnittees, as well as directly to the t.~ree mutual water oanpanies
affected. 'lbree repositories were established: 1) £1 Monte Public Library
in £1 Montei 2) Norwood Public Library in El Montei and 3) EPA Region IX
Library in San Francisco. A press release was issued by Region IX and public
notices were published in the Intercity Express (El Monte), and the San Gabriel
Valley Daily Tribune (West Covina) announcing the availability of the report,
the repository locations, the public carment period of December 13 through
Decenber 30, 1983, and the public meetiD3 on the report, scheduled by EPA
for December 19, 1983.
'n1e public meeting was held at the Arroyo High School in £1 Monte.
Iess than ten members of the public attended; no individuals in attendance
chose to make an oral statement. Before the p.Jblic meeting, a briefiD3 was
held for members of the governing boards of the three mutuals. During the
briefing, the results of the focused feasibility study were presented and
the decision-making process was explained. .
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EPA received two written cxmnents during the public ccmnent period. In
general, one a:mnentor supported alternative I>-join with another water
system-as the nDSt cost-effective solution. The other cc:mnentor supported
ground water treabnent alternatives Oller those that developed al~ernative water
supplies for the mutuals. In addition, the cc:mnentor favored carbon adsorption
treatment Oller air-stripping, because of concern over the ~tential air pollution
impacts. EPA's response to these oarrnents is sumnarized in the attached
resp::x1siveness S\.ltl'Rary.
Due to the lade of input provided by the p.Jblic ccmnent period, EPA
decided to go directly to the mutuals' shareholders for their views. This was
necessary because of the requirement that the shareholders vote on any selected
tRot. A brief fact she'!t sunmarizing the results of the focused feasibility
study was prepared. '!he fact sheet was sent to the governing boards of the
three mutuals for distribution to their shareoolders (the governing boards did
not want EPA to send the fact sheets directly). The fact sheet clearly.
stated that EPA's reoammendation was the air-stripping treatment alternative,
but that EPA would also approve alternative ~join with another water
system-since it was lower in cost and would be equally effective in protecting
public health. EPA requested that the mutuals provide us with input as to
which alternative they would accept.
Rurban Hanes Mutual Water Canpany held its annual shareholders' meeting
on February 6, 1984. During the meeting the proposed IRot was discussed.
The discussion centered on the carbon adsorption and air-stripping alternatives.
'!he shareholders voted to recarmend that EPA select the carbon adsorption
alternative. A telephone cx>nversation with a member of the governing board
indicated that the decision was based primarily on concern Oller the potential
for air pollution with the air-stripping alternative, the difficulty of
obtaining an air emission permit, and interest generated by the carbon adsorption
system purchased by the Hemlock mutual. Rurban Hanes indicated that its members
definitely were not willing to dissolve and join another water system. The
resul ts of the meet in; were conveyed to EPA in a letter (see attached
responsi veness sumnary).
Hemloc.1t and Richwood Mutual Water Canpanies did not schedule a shareholders'
Jne.1!ting to discuss the I~. The fact sheets were sent to all shareholders, and
the general view of the mutuals' members was obtained through discussions with
a ~rtion of the ~rship. A board Jneftt)er of the aemJ.ock mutual indicated
that the choice of IIDst of Hemlock's shareholders was to select carbon adsorption
treatment, particularly since they bed already purchased a carbon filter system.
It was indicated that Hemlock definitely did not want to dissolve and join
another water system.
A.board mE!!ttJer of the Richwood mutual indicated that of the mutual .
shareoolders contacted, the majority preferred the air-stripping alternative
and °did not want the mutual to dissolve. A few shareholders requested that
the governing board of the mutual call a shareholders' meeting to take a
formal vote CX'1 the alternatives.
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:
RECn!HENDED AL'reRNATIVE
Section 300.68 (j) of the National Oil aOO Hazardous Substances Contingency
Plan (NCP) (47 FR 31180, July 16, 1982) states that the appropriate extent of
remedy shall be detetmined by the lead agency's selection of th~ remedial
alternative which the agency determines is cost~ffective (i.e. ~ - the lowest
cost alternative that is technologically feasible and reliable, and which
effectively mitigates and min~izes damage to and ~ides adequate ~tection
of public health, welfare, aOO the envirorunent). Based on our evaluation of
the cost-f!ffectiveness of each of the ~£()posed alternatives, the cxmnents
received fran the public, and information received fran the State, EPA staff
recc:mnends the ins t;.al 1 at ion of an air-stripping treatment system for the
Richwood, Rurban Rc:rnes, and the Hemlock Mutual Water Canpanies.
Five alternatives were found to be equally effective in min~izing the
public health threat posed by the mutuals' contaminated well-water. Of these
alternatives, the lowest-cost alternative, E.2~tain water fran a nearby
purveyor, mutuals lease water rights-had to be dismissed fran consideration
because no nearby water ccmpany was identified that would be willing to
participate in such an arraB1ement.
Alternative ~join with arK>ther water system--was the next lowest -cost
alternative. 'Ibis alternative was not reccmnended in the feasibility study
because it would require dissolution of the mutuals, and there was no indication
at that tim= that the mutuals were willing to dissolve. When the results of
the focused feasibility study were presented to the mutuals, Hemlock aOO Rurban
Homes indicated that they were definitely not interested in dissolving. In
addition, the majority of the shareholders of the Richwood mutual that
were contacted did not want the mutual to dissolve. In response to this public
input, EPA staff is not reamnending t.~is alternative as the IRM selection.
M:>reover, implementing this alternative without the mutuals' consent would
necessitate condemning their water rights, which would significantly increase
the cost of this alternative.
Of the remaining nest~ffective alternatives, water treatment by air-
stripping is by far the lowest-cost alternative. It is less than half the cost
of the next 10Wl!st-cost alternative-treatment with a carbon adsorption system.
Consequently, EPA staff recarrnends this alternative as the nest cost~ffective
alternative for the Richwood, Rurban R::Ines and Hemlock Mutual Water Catpmies.
Richwood Mutual Water Canpany indicated to EPA that the majority of the
shareholders contacted apptoved of the EPA' s recxmnendation of treatment of
contaminated water with an air-stripping system as the 11Dst cost~ffective
alternative.
Rurban Hanes Mutual Water Catpany indicated to EPA that it prefers the
carbon" treatment alternative. 'Ibe carbon treatment alternative for Rurban
Homes is est~ted to have a capital cost of $568,000 and five-year present
worth O&M cost of $40,000, resulting in a total five-year cost of $608,000.
In contrast, the total cost for an air-stripping treatment system is
$277,000 -- $211,000 in capital costs and $66,000 in five-year present worth
O&M costs. Since the air-stripping alternative was judged to be only negligibly
less effective than carbon adsorption while still providing adequate protection
to public health and the environment, EPA staff believes that the extra cost for
the carbon adsorption system is not justified.
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Hemlock ~tua1 Water Canpany also indicated that it prefers the carton
treabnent alternative. Hemlock is in a different situation since it has
already purchased a carbon filter system. A CH2M Hill analysis for EPA judged
this purchased system to be underdesigned. '!be oost to upgrade this system to
include the margin of safety based on accepted engineering design criteria was
estimated to be $210,000. With the five-year present worth O&M cost for carbon
treatment of Hemlock's well-water estimated to be $67,000, the total five-year
cost to upgrade Hemlock's purchased carbon filter system would be $277,000.
'ltlis is well above the total five-year cost for the air-stripping alternative
of $182,000-$141,000 in capital costs and five-year present worth O&M costs
of $41,000. In addition, it could be difficult to retrofit Hemlock's purchased
system due to the limited land available at Hemlock's well site. An air-strippir
system, however, could be acc;Qulu:x3ated at the site. 'ltlerefore, EPA staff also
reccmnends air-strippil'J3 treatment of ground water as the nost cost-effective
:ffiM for the Hemlock Mutual Water Caupany.
In slmYlarY, the recxmnended cost-effective I~ for the three mutual water
ocmpanies is installation of an air-stripping system to treat contaminated
ground water fran the wells of each of the mutual water C.'OrI'q)anies. '!he costs
associated with this alternative are surrrnarized in the followil'J3 table:
DESIGN & 5-YEAR '!UrAL
crNSTROCTIOO O&M 5-YEAR
MtmJAL WATER crMPANY . CC8I'S coors COST
Richwood $173,000 $50,000 $223,000
Rurban Hanes $211,000 $66,000 $277,000
Henloc:k $141,000 $41,000 $182,000
'rol'AL $525,000 $157,000 $682,000
EPA will request all three mutuals to schedule shareholders meetil'J3s,
at which EPA will explain its decision to the mutuals. Also, the Agency
will assure the mutuals that EPA and the State will have the responsibility
to obtain any permits that EPA determines are necessary, and will work with
the South Coast Air ()Jality Management District to ensure that there are no
serious air JX)llution impacts associated with inplementation of the air-
stripping alternative.
At that t~, ~rban fbnes and Hemlock Mutual Water Canpanies will be
informed that if they do not approve the air-stripping al ternati ve, and
insist On obtainil'J3 a carbon adsorption treatment system, EPA will implement
the carbon adsorption treatment alternative if the mutuals pay the difference
between the cost of the carbon adsorption system and the estimated cost of the
air-stripping treatment alternative. In addition, EPA acknowledges that the
approval of the air-strippin; alternative by the Richwood nutual was based on
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the input of a limited munber of the" shareholders of that mutual. 'therefore,
if the Richwood IDJtual's shareholders vote to dissolve at a shareholder's
meeting, EPA will implement alternative ~join with another water systen-
since it is lower in CX)St than the air-stripping alternative and has been
judged equally effective in protecting the public health. -
OPERATIOO AND ~ (O&M)
The recxmnended action will involve operation and maintenance (O&M)
activities to ensure its continued effectiveness. 'the O&M will involve
operating the air-stripping systems for the five-year period estimated
to CCI1'plete the long-tetm remedy. The estimated present worth of the
five-year O&M costs are shown above. 'the State has requested fW1ding for
the first year of systems operation. '!bese estimated costs are shown below:
Estimated Q'1e-Year
05.M Cost
Mutual Water Canpany
Richwood
Rurban !bites
Hemlock
'lUI'AL
$12,000
$16,000
$10,000
$38,000
The California DOHS will be responsible for or.M during the period of
operation. 'the State will require the Mutuals to contribute to the cost of
continued O&M activities.
SCHEDULE
- Regional Administrator Approves :mM (siqns 10»
- Authorization to CH2M Hill to Prepare IRM Desiqn
- Beg in Des iqn of IRM
- Award Superfund State Contract for IR-1 Construction
- Begin Construction of IRM .
- Complete Implementation of IRM
May 10, 1984
May 17, 1984
May 24, 1984
July 1984
August 1984
December 1984
FlmJRE ACTIOOS
'!be State and EPA will conduct a long-tetm RI/FS project to identify
the extent of ground water contamination in all four San Gabriel areas.
Alternatives to achieve long-tem mitigation of the area-wide contamination
will be evaluated. The RI/FS is scheduled to start in May 1984. An
~ditional IQ) will be prepared at the conclusion of the project.
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~
'Ibis Reo::>rd of Decision Package was prepared aOO sent £ran EPA Region
9 to EPA Headquarters in February. '!'his addendum sumnarizes events that
have taken place since then which affect the proposed San Gabriel nM.
EPA Region 9 staff held a meeting for shareholders of the three mutuals
on March 8, 1984, to discuss EPA's reccmnended alternative aOO request that
the shareholders take a formal vote to approve the measure. At that time,
EPA informed the mutuals that EPA will ini>lement the carbon adsorption
alternative if they pay EPA for the difference in cost over the air-stripping
system. In addition, if the mutuals' shareholders voted to dissolve in a
formal meetiBJ, EPA will implement the alternative under which the mutuals
would join an:>ther water system since it is lower in cost than the air-
strippiBJ alternative and equally effective in protecting the public health.
A fact sheet sl.l1lnarizing the mutuals' options was distributed to the mutuals'
shareholders prior to the meeting.
Rurban Ranes Mutual Water Canpany conducted a door-to-door poll of its
merrbership in March, while the Rich~ and Hemlock Mutual Water Canpanies
held shareholders' meet ings . Rurban Ranes and Richwood Mutual Water
Canpanies agreed to accept the reccmnended alternative-installation of air-
stripping treatment systems. '!'he shareholders of the Hemlock Mutual Water
Canpany voted to request no action on the part of EPA and to continue with
the ini>lementation of their purchased carbon adsorption system. '!'herefore,
approval of this Record of Decision will allow EPA to install air-stripping.
treatment systems for the Rurban Hanes and Richwood ML'tual Water Canpanies.
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~le 1
SAN GABRIEL AREA 1
INITIAL REMEDIAL MF..ASURES ANALYSIS
EFFEX:TIVENESS EVAWATIOO
Criterion
weighting Factor: 3 4 3 2 4 3 5
(5)
(2) (3) Institutional (6) (1)
( 1) Reliability Operational (4) ContJlexity Ccmnunity Risk of 1UrAL
TiRE of Equipnent Canplexity Permanence to Iq:>lel1Ent Impact Failure SCORE -,
'- .
Alternative
c. Provide Bottled 5 4.5 4.5 1 4 1 5 92.5
Water
D. Join With Another 2 5 5 5 2 3 5 93..
Water System
E. Cbtain Water Fran 4 5 5 4.5 1 3 5 94
A Nearby Purveyor
F. Connect to 1 5 5 4.5 3 3.5 5 94.5
Metropolitan
Water District
G. USe Hane Treat- 5 2 3 2 2 2 2 60 -
ment Devices
H. Treat.Jnent With A 5 4 3 4 4 4 4 96
..,
Carbon Adsorption
. System At well
Discharge
I. Treatment with An 5 4 3 4 3.5 4 4 94
Ai r-Stripping
Note: Scores were based on a range of 1 to 5 with 5 indicating the best rating.
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TABLE 2
SAN GABRIEL AREA 1
INITIAL RDo1EDIM. MFA<;URES ANALYSIS
COOT OF AL'lERNATIVES
-
5-Year 5-Year 'n>tal
Capital Operation' Increased 5-Year
Alternative Costs Maintenance Water Costs Costs . I
.--.-
c. Bottled Water $9,594,000 $9,594,000
D. Join with Another Water System $ 190,000 $316,000 506,000
E. Cbtain Water fran Nearby Purveyor
1. Mutuals Maintain Rights 51,000 960,000 1,011,000
2. Mutuals Lease Rights 51,000 401,000 452,000
F. Cbnnect to Metropolitan Water District 1,236,000 50,000 348,000 1,634,000
1,270,000 140,000 1,410,000
. t,
525,000 157,000 682,000
H. Treat well Dh:;dlarge with Carbon Adsorption System
I. Treat well Discharge with Air Strippi~ System
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SAN Gr\BRIEL AREA 1
Respons i veness S\.I1Inaty
Focused Feasibility Study Final Draft
-
Background
Large areas of the San Gabriel groundwater basin, IDs Angeles County,
California, have been found to be contaminated with chlorinated hydrocarbons.
. San Gabriel Area 1, a plume of qroundwater CXX1tcnination located primarily
underneath the city. of EI fot>nte, was included in EPA' s proposed update to the
National Priorities List issued September 8, 1983.
In 1980, the State of California began an extensive well water testing
program in the San Gabriel basin which found numerous wells contaminated wi th
trichloroethylene (':OCE), tetrachloroethylene (PCE), and other chlorinated
hydrocarbons. '!tie California Department of Health Services (IX>HS) directed
public water companies in the area to periodically test their wells. State
Action levels for 'OCE and PCE were set at 5 and 4 parts per billion (ppb),
respectively, based on the Environmental Protection Agency's (EPA) Suggested }b
Adverse Resp:>nse Level (SNARL). If alternative methods of reducing PCE and 'It:E
concentrations below the Action levels (such as blending waters fran different
wells) are not effective, wells must be rE!IIDved fran service.
Currently, there are three mutual water canpanies-Richwood, Rurban fbnes,
and Hemlock-that have no alternative water supply and have been providing their
custCIIErs with water that is contaminated with PCE.at concentrations above th~
DOHS Action Level.
In May 1983, a management committee comprised of EPA, various state and
local agencies, and representatives of various water canpanies and public interest
organizations was established with California DOHS as its chair. '!tie objectives
of this committee are: 1) to find a solution for the three mutual water canpanies
that have a well contcsnination problem and have n:> alt~rnative water supply; 2) to
identify and control any '1a:/pcE sources; and 3) to develop an overall strategy for
management of the pll.1me areas-
To cw3dr~ss this first objective, EPA directed its contractor, CH2M Hill,
to '!Valuate alternative initial remedial measures (IRot) to solve the mutuals'
water contamination problens during the interim period before a final long-term
solution to groundwater contamination in the San Gabriel basin is implemented.
CH2M Hill prepared a focused feasibility study that evaluated the cost-effective-
ness of various IRM alternatives. '1bis study reocmnended the installation of a
packed tower air-stripping treatment system as t'1e DDst cost-effective alternative.
'1bis system would treat the mutuals' well-water to reduce the concentration of
PCE to bel~ the OOHS Action Level before it is distributed to their custaners.
A lower-cost alternative, under which the mutuals would dissolve and becane
part of another water system, was determined to be equally effective in minimizing
the potential threat to public health. '1bis alternative was not recamended,
however, because the dissolution of the mutuals would require a shareholders'
vote. EPA and California DOHS decided oot to recamend this alternative in
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the absence of any indication by the mutuals that it would be acceptable to
them, but the agencies consider dissolution of the mutuals to be a viable option.
'!he final draft "Focused Feasibility Study, San Gabriel", was made available
to the public on December 13, 1983. Copies of the report were distributed to
California IX>HS, the San Gabriel Management and Technical Advisory Camlittees,
and directly to the three mutual water canpanies affected. '!hree repositories
were established: 1) El Monte Public Library in El Monte; 2) H::>rwood Public
Library in El Monte; and 3) EPA Region 9 Library in San Francisco. A press
release issued by Region 9 and public notices published in the Intercity Express
(El Monte), aOO the San Gabriel Valley Tribune (West Covina) anoounced the
availability of the report, the repository locations, the public carment period
of December 13 through D!cember 30, 1983, and the. public meeting on the report
scheduled by EPA for December 19, 1983. '!he p.Jblic meeting was held at Arroyo
High School in El Monte. Before the public meeting, a briefing was held for
menDers of the governing boards of the three mutuals. During the briefing, the
results of the focused feasibility study were presented and the decision-making
process was explained.
Less t.~an ten members of the public attemed the Decemer 19th public meeting;
no individual in attendance chose to ma.1{e an oral statement. EPA received
two written a:mnents during the public ccmnent period. A list of cxrrrnentors,
copies of the written statements, and a transcript of the public meeting is
attached.
Ccmnents
In terms of which alternative initial remedial measure was supported, the
two COmments can be summarized as follows; a later section will discuss specific
comments regarding the focused feasibility study.
One canmentor supp:>rts the selection of the alternative under which the
mutuals would dissolve and join another water ccrnpany as t.~e 1tDSt cost-effective
alternative; and
One ccmnentor slJRX'rts contaminated water treatment alternatives over alternatives
that provide another source of water supply for the residents of the three mutuals,
because treatment InP.thods renove contaninated water fran the basin thereby adding
to the long-term solution of the groundwater contamination problem. In a::Idition,
this cannentor strongly objects to air-stripping as a treatment method because
of the potential p.Jblic health threat of exposure to contaminants via air emissions.
'!his cxmnentor supports the use of a carbon treatment system as the best treatment
method, instead of air-stripping. .
Response .
It. is the recomnendation of EPA and the California Department of
Health Services (DOHS) that treatment of contaminated water with an air-stripping
treatment system be selected as the initial remedial measure for the Ric::h~,
Rurban !bnes, and Hemlock Mutual Water Districts. Joinin3 with another water
system would require dissolution of the mutuals by a shareholders' vote. In the
absence of any indication by the mutuals that they would accept this alternative,
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EPA am California IXIIS have made a decision that they would not reccmnend
it, although they consider it to be a viable alternative. If the mutuals indicated
that they would be willing to accept dissolution EPA and OOHS would support
this alternative since it is lower in cost than the air-stripping t~-eabnent
alternative and has been judged to be equally effective in protecting the public
heal th .
While the initial remedial measure should be relatively compatible with the
ultimate long-term remedy in the basin, the focus of analysis is to find a solution
that will be ~equate during the interim period before a final solution is in
place.
Of all the other viable alternatives found to be equally effective in minimizing
the potential p..lblic heal th threat, air-stripping is by far the lowest-cost
alternative. 'lbe air-stripping option is less than half of the a:>st of the
carbon a3sorption alternative.
EPA acknowledges that concern has been expressed over the potential exposure
to PeE caused by air emissions fran the air-stripping treatment system. To
estimate the inpact of these emissions, EP~ staff performed a worst-case
analysis of the exposure levels of PCE that could result from the estimated
emissions of the air-stripping systems. 1'1 this analysis, an estimate was made
of the increased risk of a:>ntracting cancer due to inhalation of ambient levels
of PeE that would result from emissions from air-stripping towers installed at
the three mutuals. 'lbe analysis showed that the level of risk due to air emissions
would be a few orders of magnitU'3e below the level of increased cancer risk that
would result from ingesting water contaminated with PCE at a concentration equal
to th~ State Action Ievel-a level which California OOBS has determined to be a
safe level for human consumption. 'n1e details of this analysis are available
upon request from the EPA Region 9 office.
'lbe estimated emissions from air-stripping towers at all three mutuals
under a worst-case situation would be 145 pounds per year based on the mutuals'
annual water use, the highest CXX'lcentration of PCE found in each mutuals' wells
during the last three years, and assuming that air-stripping rerrDves all of the
PCE found in the treated water. Based on current contamination levels in the
mutuals' wells, the estimated emission rate would be only 60 pounds per year.
During preparation of the focused feasibility study report, discussions
were held with the South Coast Air Q,lality Management District (SCAaoID), which
would have to a.J?pl.o..re the air-stripping treatment alternative. SC10m indicated
that air quality nDdeling of the system with respect to dispersion of waste
gases would be required. M:x3eling studies would produce a better estimate of
the annual avera;Je increase in Elbient PCE OJncentration than the worst-case
analysis described above. '1hese studies could also be used to set the overall
height of the stack of the air-stripping system. SCACMD indicated that the mass
of pollatants expected to be discharged was relatively small caupared to other
discharges of these contaninants to the atJrDSphere.
In sunmary, EPA believes that the air pollution impact of the fl'l.oposed
air-stripping system will be minimal, am that the additional cost of the carbon
adsorption treatment system is not justified.
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EPA Region 9 will work with the SC1O'ID to ensure that there are no serious
air pollution impacts associated with the implementation of the air-striwing
treatment alternative.
-
Specific Carments and ReSIX>nses
In addition to the major carments reviewed above, other cxmnents were received
as follows:
. One a:mnentor noted that the executive sunrnary of the focused feasibility
study refers to an Action level of 8 ppb for PCE, although the State IXIiS
Action level is 4 Pfi:>.
'D\e carmentor is correct: '!he State Action level is 4 ppb. AltOOugh the
body of the report refers to the 4 PIX> Action Level for PCE, a mistake
was made in the Executive S1JIInary. Correcting this error, however, 1IIJOuld
not change any of the substantive statements made in the report.
. 'n1e president of the San Gabriel Valley Water carpany disputed the inclusion
of a $17,000 connection charge for each mutual in the cost estimate for
alternative ~joining with another water system. He states that the
only cost to the mutuals if alternative D is selected would be an estimated
charge of $200 per residence for connection to a water meter. San Gabriel
Valley Water Canpany would pay for the connections between the systems.
EPA acknowledges that the $17,000 connection charge per mutual may
not be assessed by the San Gabriel Valley Water Canpany if alternative D
is selected. In choosing the ilDSt cost-effective alternative, however,
EPA considers the total cost of ini>lementation of the alternatives, not
just those costs that would be paid by EPA, the State, or the mutuals.
'D\us, the costs EPA would pay, SUdl as capital costs of installation, and
the costs EPA would not pay, such as operation and maintenance costs, are.
added together to yield the total cost on which the decision is based.
.. In the case of alternative D, while EPA may not be required to pay for
the connection between the water mains of the mutuals and the San Gabriel
Valley Water Calpny, the costs will have to be paid by saoeone if this
alternative is implemented. 'n1erefore, it should be added to other
costs associated with this alternative to yield the total cost. 'n1e
$17 ,000 cost figure is based on the simple pipeline connection between
the mutuals' and San Gabriel Valley Water Canpany's distribution systems
described in alternatives E.1 and E.2. 'n1is cost figure was used even
though the cost for the JlDre elaborate connection of water systems that
would mst likely be used if alternative D was implemented would probably
be much higher.
In lICdition, even if these costs were deleted £ran the cost estimate for
alternative D, it would not change the ranking of the alternatives in
terms of cost and, therefore, would not alter the substantive conclusions
of the focused feasibility study.
. One a:mnentor noted that the 6 IIDnth Operation and Maintenance (O&M)
costs shown in the cost s~ies for alternatives H and I-carbon
adsorption treabnent and air-stripping treatment, respectively-appear
not to include the additional labor for operating and maintaining the
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treatment facilities. Specifically, it is mentioned that under current
California Department of Health Services (IXES) regulations, a Water
TreabDent Operator Certificate would be required for any employee to
operate the system. If the mutuals do not currently employ i~ividuals
with the required certificate, ~itional labor ex>sts should be included
under ~M costs for these alternatives.
'D1is point was discussed with staff in the Sanitary EngineeriD3 Section
of the California DeliS office in IDs Angeles. Specifically it was asked
how this regulation would affect the ~lementation of the water treatment
alternatives. [X)HS staff stated that 1Itlile under the regulations, the
operator would have to have the required Water Treatment Operators Certifi-
cate, IXES would in all likelihood allow the mutuals to operate the treatment
SystSlS in the interim as long as the operator was undergoiD3 training
provided by either the system vendor or through sane other source. '!herefore,
EPA feels the est~tes of O&M costs ~vided in the focused feasibility
study are reliable. '!he labor costs are based on an estimated 32 hours
per m:>nth of part-time labor charged at $1S/hour. ~riD3 the first 6
IIDnths of operation, there would be no charges for carbon replacement
under alternative H-treatment with a carbon adsorption system-since the
system will be installed with fresh carbon at full capacity.
. One cxmnentor stated that the implementation of water treatment system
alternatives for the mutuals is necessary to attempt restoration of. the
damaged qrourdwater resource and to prevent further spread or lIDVement
of the contaminant plume to other groundwater resources.
.EPA believes that not enough information regardiD3 the vertical and horizontal
distribution of contamination in the San Gabriel basin is available to
state wi~~ certainty whether any specific action will stop or encourage
migration of the contaminant plume. Similarly, the nature of the future
long-tem remedial actions at the site cannot be predicted with any confidence
at this time.
While the continuation of pumpin; at the mutuals' wells could be keepi~
. contamination confined in a pumping trough, it is also possible that it
could be enex>uragiD3 the lIDVement of a pocket of groundwater contamination
by drawiD3 it toward the wells. '!he influence of the mutuals' wells
cannot be detemined without further study. 'D1erefore, it is premature
to assume that continu~ the use of the nutuals' wells will prevent
pl~ migration. .
It is also not clear at this time 1Itlether the water treabnent alternatives
will fit more cost-effectively into the future long-term remedial actions
in the basin than the alternative through which the mutuals dissolve and
join another water system. For example, if the longtem solution included
installation of a treatment alternative for the larger water system (that
the mutuals joined), econanies of scale could result in a lower total
cost to treat the water, than if separate treatment systems were installed.
In ~ition, the long-tem control of the epntaminant plume may require
shuttiD3 down sane presently operating wells and dri11iD3 new wells. If
this occurs, installation of water treatment alternatives at presently
operatin; wells may not result in a lower long-term ex>st to solve the San
Gabriel basin's groundwater contamination problem.
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Of course, the treatment alternatives may fit in better with the longterm
solution, but it is premature to assume that they will.
In stmmary, EPA feels the advantages of water treatment altePtatives
are too uncertain at this time for use as a major factor in the selection
of an initial remedial measure at this site. .
. cne ccmnentor notes that carbon adsorption ranked highest in the focused
feasibility study's effectiveness evaluation, even before ex>nsideration
is made of any potential air p::>llution impacts of the air-stripping
alternative.
'!he total effectiveness score for carbon adsorption, air-stripping, and
joining with aoother water system was 96, 94, and 93, respectively. When
using a rating system like the one utilized in the effectiveness evaluation
of initial remedial measure alternatives, these relatively small differences
in total effectiveness scores (under 3.3%> are insignificant for the
purposes of selecting an appropriate remedy. As discussed above, EPA
believes that the air pollution ~ct of the air-stripping alternative
is insignificant when c.'CI'Ipared to risk of consuming drinking water with PCE
concentration at the IXES action level. '!herefore, EPA has judged
all three of these alternatives to be equally effective in minimizing the
threat of haJ:1tl to public heal th.
Post~t Period Activities Concerning the 'lhree Mutual Water Canpanies
Due to the lade of input provided during the publiccxrrment period, the
Region decided to go directly to the mutuals' shareholders for their views.
'!his was necessary because of the requirement that the shareholders vote on any
selected IR-t. A brief fact sheet surrmarizing the results of the focused feasibility
study was prepared. '!he fact sheet was sent to the g0\7erning boards of the
three mutuals for distribution to their shareholders (the governing boards did
not want the Region to send the fact sheets directly to the shareholders>. '!he
fact sheet clearly stated that EPA' s reccmnendation was the air-stripping
treatment alternative, but that EPA would also approve alternative D-join with
another water system-since it was lower in cost and would be equally effective
in protecting public health. '!he Region requested that the mutuals provide us
with input as to which alternative they would prefer.
Rurban R:lnes Mutual Water Calpany held its annual shareholders' meeting on
February 6, 1984. During t.~e meeting the f)I:'Oposed IR-t was discussed. '!he discussion
centered on the carbon adsorption and air-stripping treatment alternatives. '!he
share.~lders voted to rea:mnend that EPA selected carbon adsorption alternative.
A telephone conversation with a rneni>er of the governing board indicated that the
decision ~ based primarily CX'1 concern over the potential for air p::>llution,
the difficulty of obtaining an air emission permit, aDd interest generated by
the carbon adsorption system PJI'chased by the Hemlock mutual. JbJrban IbDes
indicated that its members definitely were not willing to dissolve and join
another water system. '!be results of the annual meeting were CDlveyed to EPA
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~ion in a letter.
attad1ed . ]
[A aJpy of the fact sheet and Rurban Hanes letter to EPA is
Hemlock and Ric:::hw00c3 Mutual Water Canpanies did not schedule a shareholders'
meeting to discuss the IRot. '!be fact sheets were sent to shareholdets, and the
general view of the ItUtuals' members was obtained through discussions wit.t} a
p:>rtion of the JDe!ItIership. A board menDer of the Hemlock mutual indicated that
the choice of nost of Hemlock's shareholders was to select carbon adsorption
treatment, particularly since they had already purd1ased a carbon fil~er system.
It was indicated that Hemlock definitely did not want to dissolve and join another
water system.
A board member of the Richwood mutual indicated that the majority of the
mutuals' shareholders contacted preferred the air-stripping alternative and did
not want the mutual to dissolve. '!be views of relatively few shareholders was
obtained, however, and a significant fraction stated that they were willing to
dissolve the mutual and join another water system.
Resp:mse
Richwood Mutual Water Canpany indicated to the EPA that the majority of the
shareholders contacted approve of EPA' s recc:mnendation of treatment of contaminated
water with an air-stripping system as the most cost-effective alternative.
Rurban 1bnes Mutual Water Catpany indicated to EPA that it prefers the
carbon treatment alternative. '!be carbon treabnent alternative for Rurban Hanes
is estimated to have a capital cost of $568,000 and S-year present worth operation
and maintenance (O&M) costs of $40,000, resulting in a total 5-year cost of
$608,000. In contrast, the total cost for an air-stripping trea~nt system is
$277,000--$211,000 in capital costs and $66,000 in 5-year ~sent worth O&M
costs. As discussed above, the Region believes that that the air ~l1ution
inpact of an air-stripping system is insignificant. In addition, since both
alternatives are judged to be equally effective in protecting public health, the
Region believes that the extra cost for the carbon adsorption system is not
justified. .
Hemlock Mutual Water Canpany also indicated that it prefers the carbon
treatment alternative. Hemloc.1t is in a different situation than Rurban fbnes
since they have already purchased a carbon filter system. A CH2M Hill analysis
of Hemlock's system requested by EPA judged this purchased system to be underdesigned.
'lbe cost to upgrade this system to include the margin of safety based on accepted
engineering design criteria was estimated to be $210,000. With the S-year present
worth O&M cost for carbon treatment of Hemlock's wellwater estimated to be
$67,000, the total S-year cost to upgrade Hemlock's purchased carbon filter
system would be $277,000. 'this is well above the total 5-year cost of $182,000
for the air-stripping alternative-$141 ,000 in capital costs and S-year present
worth O&M costs of $41,000. In addition, it could be difficult to retrofit
Hemlock's purchased system due to the limited land available at the Hemlock's
well site. An air-stripping system, however, could be a~lIodated at the site.
'therefore, the Region also reccmnends air-stripping treatment of groundwater as
the nest cost-effective IRM for the Hemlock Mutual Water Canpany.
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.'
'D1e Region will request all three mutuals to schedule a shareholders' meeti~,
at which the Region will explain its decision. Also, the Region will assure the '
mutuals that EPA will have the reSFOnsibility to obtain any necessary permits,
and will work with the SOuth Coast Air ~ality Management District to ensure
that there are no serious air pollution impacts associated with impl~ntation
of the air-stripping alternative.
At that time, Rurban Hanes and HEmloc.1c Mutual Water Canpanies will be informed
that if they do not approve the air-stripping alternative, and insist on obtaining
. a carbon adsorption treatment system, EPA will implement the carbon adsorption
treatment alternative if the mutuals pay the difference between the cost of a the
carbon adsorption system and the estimated oost of air-stripping treatment. In
a::1dition, EPA acknowledges that the approval of the air-stripping alternative by
the Richwood mutual was based on the input of a limited nunDer of the shareholders
of the mutual. 'D1erefore, if the Rich'«Xld mutual's shareholders vote to dissolve
at a shareholders' meeting, EPA will implement altemative D - join with another
water system - since it is lower in cost than the air-stripping alternative and
has been jOOged equally effective in protecting the public health.
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AOOENID!
'Ibis reSiXX'lSiveness SlJlTl'Rary was prepared as part of the Reoot:d of
Decision package and sent fran EPA Region 9 to EPA Headquarters iri. February
1984. 'Ibis addeooum sumnarizes oamnmity relations events that haVe
occured since then which affect the proposed San Gabriel IJIot.
EPA Region 9 staff held a meeting for shareholders of the three
nutuals on March 8, 1984, to discuss EPA's reccmnended alternative and
request that the shareholders take a formal vote to approve the measure.
At that time, EPA informed the mutuals that EPA will inq:>lement the carton
adsorption alternative if they pay EPA for the difference in cost ewer the
air-stripping system. In addition, if the mutuals' shareholders voted to
dissolve in a formal meeting, EPA will inq:>lement the alternative under
which the mutuals would join another water system since it is lower in
cost than the air-stripp~ alternative aOO equally effective in protecting
the public health. A fact sheet sunmarizing the mutuals I options was
distributed to the mutuals I shareholders prior to the meeting.
Rurban lbnes Mutual Water Canpany conducted a door-~r poll of
its membership in March, while the Richwood and Hemlock Mutual Water
Canpanies held shareholders I meetings. Rurban Ibnes and Richwood Mutual
Water Canpanies SJreed to accept the recr.mnended alternative-installation
of air-stripping treatment systems. 'Ibe sharemlders of Hemlock Mutual
Water Canpany voted to request 00 action on the part of EPA and to continue
with the inplementation of their purchased cart:on adsorption system.
'Iberefore, EPA will install air-stripping treatment systems for the
Rurban Hanes and Richwood Mutual Water Canpanies ooly.
Copies of the fact sheets distributed to the mutuals' shareholders
prior to the meeting, as well as oopies of the letters fran the three
mutuals to EPA describing the results of their shareholders I votes are
attached.
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/'
Hazardous Waste Collection
Information Resource Center
. US EPA Region 3
Philadelphia, PA 19107 PBES"- Ll4 120
..- ...._AL REPORT DATA
(PletUe TeQd Instf'UCIIOnS on the ,everse before completi"g)
,. REPORT NO. 12. 3. RECIPIENT.S ACCESSION NO.
EPA/ROD/R09-84/004
4. TITLE AND SUBTITLE 5. REPORT DATE
SUPERFUND RECORD OF DECISION: 05/11/84
San Gabriel Area 1, CA 6. PERFORMING ORGANIZATION CODE
[5J.
7. AUTHORIS) 8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM EL.EMENT NO.
". CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS 13. TYPE OF REPORT AND PERIOD COVERED
Final ROD Report
U.S. Environmental Protection Agency 14. SPONSORING AGENCY CODE
401 M Street, S.W.
Washington, D.C. 20460 800/00
15. SUPPL.EMENTARY NOTES
16. ABSTRACT
The San Gabriel Area I site is affected by one of four contaminated ground water
plumes affecting the San Gabriel ground water basin, approximately 40 miles east of
Los Angeles. Testing of wells by the California Department of Health Services (DOHS)
found areas of the basin contaminated with trichloroethylene ( TCE), tetrachloroethylene
(PCE), and other chlorinated hydrocarbons. The DOHS has set Action Levels for TCE
and PCE at the EPA suggested no adverse response level (SNARL) of 5 ppb and 4 ppb,
respectively. The three mutual water companies whose wells have been affected. by the
contamination serve a population of approximately 200,000.
The selected initial remedial measure (IRM) is installation of an air stripping
system to treat contaminated ground water from the ~ffected water mutual wells. The
capital cost for the project is $525,000 and annual O&M is estimated to be $38,000.
Key Words: Ground Water Contamination, Environmental Standard, Initial Remedial
Measure, Risk Level, SNARL, Air Quality, Air Permi t, Carbon Adsorp-
tion, Air Stripping, Data Adequacy, Trend Analysis
17. KEY WORDS AND DOCUMENT ANAL.YSIS
Ia. DESCRIPTORS b.IDENTIFIERS/OPEN ENDED TERMS c. COSA TI Field/Group
Record of Decision
San Gabriel Area I, CA EPA Report Collection
Contaminated media: gw Information Resource Center
Key contaminants: solvents, TCE, PCE US EPA Region 3
Philadelphia, PA 19107
1B. DISTRIBUTION STATEMENT 19. SECURITY CLASS (TI.is Repo,r) 21. NO. OF PAGES
None 64
20. SECURITY CLASS (TI.is PQge) 22. PRICE
None
EPA Fo,m 2220-1'(R... .-77)
PREVIOUS EDITION IS OBSOL.ETE
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ROD ISSUES ABSTRACT
Site:
-
San Gabriel Area 1, California
Region:
IX
AA, OSWER
Briefing Date:
March 14, 1984
SITE DESCRITION
The San Gabriel Area I site is affected by one of four contaminated
ground water plumes affecting the San Gabriel ground water basin,
approximately 40 miles east of Los Angeles. Testing of wells by the
California Department of Health Services (DOHS) found areas of the
basin contaminated with trichloroethylene (TCE), tetrachloroethylene
(PCE), and other chlorinated hydrocarbons. The DOHS has set Action
Levels for TCE and PCE at the EPA suggested no adverse response level
(SNARL) of 5 ppb and 4 ppb, respectively. The three mutual water
compafiies whose wells have been affected by the contamination serve a
population of approximately 200,000.
Selected Alternative
The selected initial remedial measure (IRM) is installation of an
air stripping system to treat contaminated ground water from the
affected water mutual wells. The capital cost for the project is
$525,000 and annual O&M is estimated to be $38,000.
ISSUES AND RESOLUTIONS
1.
SNARL's can be appropriately utilized as
guides for deciding if an IRM should be
conducted. They can also be used as an
aid to establish cleanup levels. SNARL's
at 10-6 risk are acceptable goals.
IRM alternatives should be developed
to meet the 10-6 level if they are cost
effective. If this level can not be
achieved, a higher risk level might be
necessary.
-1-
KEY WORDS
. Ground Water
Contamination
. Environmental
Standard
. Initial Remedial
Measure
. Risk Level
. SNARL
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3.
4.
San Gabriel Area 1, California
March 14, 1984
Continued
ISSUES AND RESOLUTIONS
2.
Releases of ground water contaminants
(i.e., organic solvents) to the atmosphere
as a result of remedial technologies such
as air-stripping should be evaluated to
ensure that a public health threat is not
being transferred from one media to another.
A permit is not required for these air re-
leases under current EPA pOlicy. However,
technical requirements of the air program
should be followed. Although the site was
in a non-attainment area, air emissions from
this facility do not pose a public health
threat locally and do not measurably
contribute to area-wide air contamination.
The lowest cost alternative for this site
was dismissed from further consideration
because nearby water companies were not
willing to lease water rights from the
affected mutuals. The second lowest cost
alternative was also dismissed because
it involved dissolution of the water
mutuals. Of the remaining alternatives,
water treatment by air stripping was the
most cost-effective alternative.
Two of the water mutuals supported a
carbon adsorption treatment alternative.
One mutual indicated a preference for
carbon adsorption treatment and the other
was already treating water with a carbon
adsorption system. It was determined that
the operating carbon adsorption system was
underdesigned and it would be considerably
more expensive to upgrade than to install
an air-stripping system.
EPA has decided that the extra cost for
the carbon adsorption system was not
justified since the air stripping
alternative is negligibly less effective.
ROD briefings should contain the most recent
and historical data (e.g. analytical) so
that contaminant migration and contamina-
tion levels can be analyzed.
-2-
KEY WORDS
. Air Quality
. Air Permit
. Carbon
Adsorption
. Air Stripping
. Data Adequacy
. Trend Analysis
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3-1,/-g,/
SAN GABRIEL AREA 1
RECORD OF DECISION BRIEFING
PURFOSE
o
To obtain the Assistant Administrator's approval for initial remedial
measures at the San Gabriel Area 1 site in El Monte, California. The
initial remedial measure recommended by EPA Region IX and the California
Department of Health Services (DOHS) is the installation of packed
tower air-stripping systems at the wells of three mutual water companies
to treat ground water contaminated with tetrachloroethylene. .
ISSUES OF CONCERN
o
The three/mutual
alternatiwe that
The mutu~ls must
more mu~6als may
approved by EPA.
water companies affected by the IRM have recommended an
is more costly than the cost-effective alternative.
approve the IRM through a shareholder vote. One or
vote to install a more expensive alternative than that
BACKGROUND
o
San Gabriel Area 1 is one of four plumes of ground water contamination
located in the San Gabriel ground water basin that are on the Proposed
National Priorities List. The San Gabriel basin is an important source
of ground water located underneath the San Gabriel Valley, about
40 miles east of Los Angeles. The basin covers an area of approxilnately
700,000 to 1,000,000 people, as well as water for industrial uses.
o
Contamination was discovered in December 1979, when Aerojet Electrosystems
in Azusa analyzed samples taken from a municipal water supply well
adjacent to the Aerojet property. Samples showed trichloroethylene
(TeE) concentrations of 1800 parts per billion (ppb).
o
This discovery prompted a joint State/local sampling program in the
entire basin and outlying areas. As of now, sampling in the basin has
found 56 wells contaminated wit;! TCE, tetrachloroethylene (PCE), and
other chlorinated solvents.
o
Based on existing data, it appears that there are several distinct plUmes
of ground water contamination in the basin.
o
DOHS has set Action Levels for TeE and PCE of 5 and 4 ppb, respectively.
These levels are based on the EPA suggested No Adverse Response Levels
(SNARL) and represent the levels at which the risk of contracting cancer
due to the ingestion of drinking water contaminated with TeE or PCE is
10-6.
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o
Cua-ently, there are three mutual water canpanies - RichY.Q:)(j, Rurban
Hames, and Hemlock - that have no alternative water supply and have been
providing their customers with water that is contaminated with PCE at
concentrations above the OOHS Action Level. Mutual water canpanies are
cooperatively owned water companies; in other words, the customers own
shares in the canpany. These three mutuals serve approximately 700
households with drinking water. The most recent sampling data shows the
following PCE concentrations in the mutuals I wells:
Richwood: Well No.1 -- 62 ppb; Well No.2 - 92 ppb
Hemlock: South Well -- 50 ppb; North Well -- 38 ppb
Rurban Homes: Well No.1 - 1.7 ppb; Well No.2 - 3.7 ppb
o
Although Rurban's Hanes I well - water presently meets the Action Level,
this is the first sampling episode in which the wells have had
concentrations of less than 4 ppb PCE since contamination was first
detected in October 1980.
o
EPA cons idered Emergency Action to meet t..'1e first objective, however,
this was rejected because the levels of TCE and PCE in the mutuals'
wells did not exceed the 10-day health advisory. This objective is now
being addressed by the initial remedial measures described in this
brief irg.
ENFORCEMENT
o
At Region IX' s nquest, the Field Investigation Team (FIT) has prepared
a list of Potentially Responsible Parties (PRP's) for use in preparifX,;j
RCRA Section 3007/CERCLA Section 104 letters.
o
The Region sent 16 section 3007/104 letters to PRP's on August 19, 1983,
after FIT provided an initial list of PRP' s. This list was based on the
1980 RWQCB study and, therefore, included only two facilities in Area 1.
When the final FIT list was provided, the Region sent 72 additional
section 3007/104 letters on Janua-ry 12, 1984; 31 of these PRP's were
located in Area 1.
o
Region IX staff are reviewirg responses to these letters as they are
received to identify candidates for site inspections and further
investigations. Four of the initial list of 16 PRP's nave been referred
to FIT for site inspections, however, none of these facilities are
located in Area 1.
o
Since evidence linkifX,;j spec if ic responsible parties to ground water
contamination in Area 1 has not yet been produced, Administrative Orders
cannot be used to compel implementation of the IRM. Therefore, it is
recanmended that Trust Furd monies be used for IRM implementation.
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-3-
RESULTS OF THE FOCUSED FEASIBILITY STUDY
o
Seven IRM alte~natives we~e evaluated in detail as to thei~ effectiveness
and cost in the focused feasibility study:
Alte~native C - Bottled wate~
Alte~native D - Join with anothe~ wate~ system
Alte~native E.l - Obtain wate~ f~om a ne~by purveyor, mutuals
maintain wate~ ~ights
Alte~native E.2 - Obtain water f~om a ne~by purveyo~, mutuals
lease water ~ights
Alte~native F - Connect to the Metropolitan Wate~ Dist~ict
Alte~native H - Treat well disch~ge with carbon adsoLption system
Alternative I - Treat well disch~ge with air-stripping system
o
Costs and effectiveness scores fo~ these seven alte~natives aYe shown in
Table 1. All seven of these alternatives that received final considecation
we~e considered to be equally effective in meeting the objective of the
IRM. The~efore, the final decision was based on cost.
o
Alte~native E.l .and E.2 had to be dropped from furthec consideration
because no ne~by wate~ purveyo~ was identified that would provide watec
undec either of those alte~natives.
o
Altecnative D, was the next lowest cost alternative aftec E.l. It was .
not ceooITmeooed as the cost-effective alternative because it would
require dissolution of the mutuals. At the time the focused feasibility
study was prepared, there was no indication that the mutuals would be
willing to dissolve.
o
Alternative I - treat.'11ent with ai~-stripping syste.n -- '.vas recorrmeooed
as the most cost-effective alternative since it was the lowest cost of
the remaining alte~natives, and was judged to be equally effective in
protecting public health.
Ca.1MUNITY RELATIONS
o
Ru~ban Homes held a shaceholde~s' meeting; a majority of those sh~eholde~s
in atteooance voted to recanmend that EPA select the c~bon adsorption
alte~native. Rurban Homes membe~s were definitely not interested in
dissolving the mutual. The decision was gased on conce~n over the
potential air pollution liTIQact of ai~-stripping towe~s, difficulty in
obtraining an ai~ emissions peonoit, and interest genecated ovec Hernloc's
pucchase of an c~bon filte~ system.
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\.
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-4-
o
Hemlock and Richwood Mutual Water Companies did not schedule shareholders'
meetings. The general view of the shareholders was obtained through
discussions with a portion of their members. A Hemlock board maTIber
indicated that the choice of most of Hecilock' s membership was to select
carbon adsorption. The majority of the Richwcod shareholders contacted
preferred the air-stripping alternative.
RECCMMENDATION OF THE COST-EFFECTIVE INITIAL REMEDIAL MEASURE
o
EPA Region IX and California CORS recorrmerd that installation of an
air-stripping treatment system be selected as the rrost cost-effective
solution. The lowest cost alternative - obtain water from a nearby
purveyor, mutuals lease water rights - cannot be implemented" because
no water- purveyor- has been identified that would participate in such
an arr-anganent. Although the next lowest cost alter-native is for- the
mutuals to join with another- water system, none of the mutllals has
indicated a willingness to dissolve as would be requir-ed under- this
alter-native. Ther-efore, in response to public input, the Region and
COHS do not r-ecorrmend the selection of this alternative. Of the r-emaining
alternatives, air--str-ipping treatment is by far the lowest cost. In
addition, it has been judged to be as equally effective in i?r-otecting
the public health and welfare as any of the other alter-natives.
o
Although Rurban Hanes pr-efer-s the carbon adsor-ption alternative, this
option is over- twice the cost of air-stripping. To address their concerns
over the potential for air pollution, Region staff prepared a worst case
analysis of the potential air- pollution linpacts. Based on this analysis
and CH2M Hill's discussions wiL~ the South Coast Air- Quality Mangement
District (SCQMD), the Region has determined that the air pollution linpact
of air--stripping towers installed at the thr-ee mutuals I we.l.l sites will
be negligible. In addition, SPA will canply with all rules and pr-ocedures
of the SCAQMD in implementing this alternative.
o
HEmlock's situation is slightly different from that of Rurban Homes in
that they have already installed a carbon treatment system. A CH2M Hill
analysis of the design of this system prepared at the request of
Region IX concluded that this syteTI was underdesigned and lacking a p::-oper
margin of safety. Upg::-adirg this system to the desi9n standards based
on accepted engineering design criteria was estlinated to cost $210,000.
Therefore, the total costs of a retrofit of their system would be almost
$100,000 rror-e than the ai::--stripping system. Consequently, the Region
and Califor-nia OORS r-ecommend the installation of the air-str-ipping
system for- the HEmlock mutual as well.
o
EPA met with shareholders from the three mutuals on March 8, to discuss
EPA's ::-ecommended alternative and r-equest that the shareholders take
a formal vote to appr-ove the measure. At that time, EPA informed the
mutuals that EPA will implement the carbon adsor-ption alternative if
they pay EPA for the difference in cost over air-st::-ipping. In addition,
EPA acknowledges that a significant fraction of Richwcod's members
pr-efer-red to dissolve. Therefore, if the membership votes to dissolve
in a formal meeting, EPA will implanent the alter-native under which
Richwood would join another water system since it is lower in cost than
the air-stripping alternative and equally effective in pr-otecting the
public health.
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. -.. ._-~~_..... ._----- -.'. ... ,
-5-
FU'IURE REMEDIAL ACI'ICNS
o
A RI/FS in the San Gabriel basin will begin in April 1984, to determine
the extent of ground water contamination and to reoommend cost-effective
lo~-term remedial action for San Gabriel Areas 1 through 4. It is
estimated that the RI/FS may take three years to canplete, and that the
final remedial action will not be in place until five years from now.
NEXT STEPS
o
San Gabriel Area Sites are added to NPL (final)
March 30, 1984
o
Assistant Administrator Approves IRM (signs ROD)
March 30, 1984
o
Award Superfund State Contract Eor Implementation
of IRM
April 6, 1984
o
Begin Design and Const~ction of IRM
April 1984
o
Complete Implementation of IRM
October 1984
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TABLE 1
SAN GABRIEL AREA 1
RECORD OF DECISION BRIEfING
COST~tFFECTIVENESS EVALUATION
Capital
Costs
5-Year-
Pr-esent Wor-th
Total
5-Year-
Total
Effectiveness
Annual Costs
Costs
Score
C.
Bottled Water
$9,594,000
92.5
9,594,000
D.
Join with Another Water Systsn
I
!
\. !
i"
I.
f
I
190,000
316,000
506,000
93
E.
Obtain Water from Nearby Purveyor
J
\".
{"
1.
2.
Mutuals Maintain Rights
Mutuals Lease Rights
51,000 960,000 1,011 ,000 94
51,000 401,000 452,000 94
1,236,000 398,000 1,634,000 94.5
l, 270,000 140,000 t ,410 ,000 96
F.
Connect to Metropolitan Water District
H.
Treat Well Discharge with Carbon
Adsorption System
1.
Treat Well Discharge with Air-Stripping
System
94
525,000
157,000
682,000
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