United States
Environmental Protection
Agency
Office of
Emergency and
Remedial Response
EPA/ROD/R02-87/050
September 1987
&EPA Superfund
Record of Decision
Vega Alta, PR
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TECHNICAL REPORT DATA
/Please read Instruction* on the reverse before completing)
1. REPORT NO.
EPA/ROD/R02-87/050
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
SUPERFUND RECORD OP DECISION
Vega Alta, PR
First Remedial Action
9. REPORT DATE
September 29, 1987
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND AODRESS
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME ANO AOORESS
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
13. TYPE OF REPORT ANO PERIOD COVERED
Final ROD Report
14. SPONSORING AGENCY CODE
800/00
15. SUPPLEMENTARY NOTES
18. ABSTRACT
The Vega Alta Public Supply Wells site is a public water supply well field located in
the municipality of Vega Alta, Puerto Rico, approximately 32 km west of San Juan where
ground water ie the- primary source of water. The well field consists of eight active •
wells and two" inactive wells. It currently supplies about 3.8 million gallons per day
of water to Vega Alta and surrounding residential areas. The Puerto Rico Aqueduct and
Sewer Authority (PRASA) is responsible for operation and maintenance of the public water
supply system. The first indication_of contamination was discovered in June 1983, when
a survey of public water wells made by the U.S. Geological Survey detected 574 ug/1 of
trichloroethylene (TCE) in the Ponderosa public supply well. Other VOCs were detected
at lower concentrations in non-public wells in the well field system and ground water
contamination was suspected. In June and August of 1983 Ponderosa and well GE 1 were
shut down by PRASA because of contamination, respectively. This shut down caused a
potential water supply shortage in Vega Alta. PRASA constructed well Bajura 3 to
eliminate the shortage. In 1984 an air stripper was constructed at the Ponderosa well
and operated until May 1985 when technical problems arose with the air stripper.
Currently, ground water is contaminated with 1,1,1-trichloroethene, tetrachloroethene,
1,2-dichloroethene, 1,1-dichloroethene and other VOCs.
(See Attached Sheet)
17.
KEY WORDS ANO DOCUMENT ANALYSIS
DESCRIPTORS
b.lOENTIPIERS/OPEN ENDED TERMS C. COSATI Field/Group
Record of Decision
Vega Alta, PR
First Remedial Action
Contaminated Media: gw
Key contaminants: VOCs, PCE, TCE
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plvv2--c:~'^?^"r'-'^
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EPA/ROD/R02-87/050
Vega Alta, PR
First Remedial Action
16. ABSTRACT (continued)
The selected remedial action for this site includes: treatment of PRASA wells GE 1,
GE 2 and Bajura 3 by individual treatment systems with discharge of treated effluent
into the PRASA distribution system for public use; treatment of Ponderosa well by
scaling pretjreatment and air stripping; discharge of treated effluent from the Ponderosa
well to Honda Creek; shut down of Monterrey 2 and G&M private wells with hookup to the
PRASA distribution system; and initiation of a subsequent RI/FS to fully assess and
evaluate the source(s) of contamination. The estimated capital cost for this remedial
action is $4,106,000 with annual O&M of $581,000.
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DECLARATION STATEMENT
Record of Decision
Vega Alta Public Supply Wells
SITE NAME AND LOCATION
Vega Alta Public Supply Wells Site, Vega Alta, Puerto Rico.
STATEMENT OF PURPOSE
«.
This decision document presents the selected remedial action
for the Vega Alta Public Supply Wells Site, developed in
accordance with the Comprehensive Environmental Response,
Compensation and Liability Act of 1980, as amended by the
Superfund Amendments and Reauthorization Act of 1986, and to
the extent practicable, the National Oil and Hazardous
Substances Pollution Contingency Plan, 40 CFR Part 300,
published November 20, 1985.
STATEMENT OF BASIS
This decision is based upon the administrative record for the
Vega Alta Public Supply Wells Site. A copy of the record is
available for review at the information repository for the
site and at the EPA Caribbean Field Office. The following
documents, which are part of the administrative record, were
primarily relied upon in making this decision:
- Remedial Investigation Report, Vega Alta Public Supply
Wells Site, prepared by NUS Corporation, May 1986
- Feasibility Study Report, Vega Alta Public Supply Wells
Site, prepared by Ebasco Services Inc. , July 1987
- The attached Summary of Remedial Alternative Selection
for the Vega Alta Public Supply Wells Site.
- The attached Responsiveness Summary for the site, which
incorporates public comments received.
- Staff summaries and recommendations.
DESCRIPTION OF SELECTED REMEDY (Groundwater Contamination
Operable Unit)
The remedial alternative presented in this document is the
first operable unit of a permanent solution for the site.
It focuses on groundwater contamination. Source control
actions will be considered at a later date once an additional
remedial investigation/feasibility study is completed.
This Record of Decision calls for the following actions:
0 Treatment of Puerto Rico Aqueduct and Sewer Authority (PRASA)
wells GE 1, GE 2, and Bajura 3 by individual
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-2-
treatment systems generally consisting of scaling pretreatment,
air stripping and possibly activated carbon. The specifics
of the treatment system will be determined during the
Remedial Design.
0 Treated effluent will be discharged into the PRASA distribution
system for public use.
0 Treatment of Ponderosa well by scaling pretreatment and air
stripping.
0 Treated effluent from the Ponderosa well will be discharged to
Honda Creek in accordance with the existing National Pollutant
Discharge Elimination System (NPDES) permit; the effluent
will meet the same quality requirements as for PRASA wells
GE 1, GE 2, and Bajura 3 such that Ponderosa treated water
can eventually be utilized for water supply in the future.
Activated carbon treatment could be added to this treatment
process should the need arise.
0 Monterrey 2 and G&M private wells will be shut down and
each user will be connected to the PRASA distribution system.
0 A subsequent remedial investigation/feasibility study will
be initiated to fully assess and evaluate the sources of
contamination.
DECLARATIONS
Consistent with the Comprehensive Environmental Response,
Compensation and Liability Act, as amended, and the National
Oil and Hazardous Substances Pollution Contingency Plan, 40
CFR Part 300, I have determined that the selected remedy is
protective of human health and the environment, attains federal
and state requirements that are applicable or relevant and
appropriate for this groundwater contamination operable unit,
and is cost-effective. The statutory preference for treatment,
while not fully satisfied in that the sources still need to
be considered, is partially addressed in that the groundwater
treatment system reduces the toxicity and volume of contaminants.
The Commonwealth of Puerto Rico has been consulted and agrees
with the selected remedy. A letter from the Chairman of the
Environmental Quality Board of Puerto Rico is attached.
I have also determined that the actions being taken are
appropriate when balanced against the availability of Superfund
monies for use at other sites.
Date / CHRISTOPHER J 7"£>ftGGETT
Regional Administrator
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SUMMARY OF REMEDIAL ALTERNATIVE SELECTION
VEGA ALTA PUBLIC SUPPLY WELLS SITE
PUERTO RICO
SITE LOCATION AND DESCRIPTION
This summary addresses management of contaminated groundwater
as the first site Operable Unit since it is considered critical
for protection of public health and reduction of ri'sks
associated with ingestion of the groundwater. Source* control
actions are considered less critical from a public health
standpoint and will be addressed at a later date once additional
source investigations are completed.
The Vega Alta Public Supply Wells Site is a public water supply
wellfield located in the municipality of Vega Alta, Puerto
Rico (Figure 1). Vega Alta is in the north coast limestone
region of Puerto Rico, approximately 32 kilometers west of
San Juan. The wellfield consists of approximately 8 active
and 2 inactive wells and is currently supplying approximately
3.8 million gallons per day of water to Vega Alta and surround-
ing residential areas (See Figure 2). Groundwater is the
primary^source of water for the public water system in Vega
Alta. The Puerto Rico Aqueduct and Sewer Authority (PRASA)
is responsible for operation and maintenance of the public
water supply system.
Wells in the Vega Alta area obtain water principally from the
Aguada and the Upper Cibao Limestone "formations. The thickness
of these two formations is approximately 130 meters and the
depth to the water table ranges from 20 to 60 meters, depending
on the surface elevation. The regional groundwater flow
direction is north toward the Atlantic Ocean, however, pumping
of the wellfield has caused local drawdown cbnditions that
alter the direction of flow in the vicinity of the operating
wells.
Economic activity within the Municipality of Vega Alta includes
agriculture (sugar cane and dairy farming) and light industrial
manufacturing. Public sewer and water systems are present,
however, many industrial facilities use onsite septic systems
for sewage disposal.
The main concentration of industrial facilities is directly
north of the Town of Vega Alta and is within the public
wellfield areas (See Figure 3). Many of the industries
are currently using chlorinated solvents in their operations.
Most of the industries lease their plant facilities from the
Puerto Rico Industrial Development Company (PRIDCO). Numerous
tenants have operated in most of the PRIDCO buildings, the
first of which was constructed in 1965.
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AfLANJICl/ OCM.V
at* n.
SOURCE: • Rand Mcftollyt Company. Uttdbyptnnitslon. All rights rawnwd.
LOCATION MAP
VEGA ALTA SITE. VEGA ALTA. PR
SCALE AS SHOWN
FIGURE 1
CORPQRAnON
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RASA WASTE
WATER TREATMENT
t*9C MAF B A PORTION OF THE US.0.9. VEOA ALT*. PM OUAORANOLC (T.S MINUTE SERIE* If«t, PHOTOMEVISEO 1*121
OOMTOUR INTERVAL W METCR*.
SITE CONDITIONS
VEGA ALTA SITE.VEGA ALTA.PR
SCALE I > 20,000
® VEOA TRONICS INC (PRIVATE)
(8) ABLE MANUFACTURING (PRIVATE)
NOTE' I. LOCATIONS OF VEOA TRONICS ft ABLE MANUFACTORINO TAKEN FROM EPA TAT.
FIELD VERIFICATIONS HAVE NOT KEN MADE.
S. SEE FI8URE t-S FOR A DETAILED MAP OF THE PRIOCO INDUSTRIAL
FACILITIES.
J. SEE FIOURE 4-t FOR A DETAILED MAP OF THE EXISTING WATER SUPPLY »
MONITORING WELL LOCATIONS.
MOO
FIGURE
BOO 1000 JOOO 4000FCCT
ORATOM
A Hafcburton Company
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f*oco Deve
I \UCNT (UNOe* CONST)
s-to
H/f f!N. LAND AOMIMISV^.-ATION
PONOCROZA HCSIDCNTIM.I*
OCVELOPMCNT
lur • * FOUTIOK 0» TMt U*«t
HtVIOCO ItMI. CONtOU* INflllVAL K»M(T(M
0J« • UlfTIM •C1L * HU1 Muril mMMII. IHI ft«UM ••!»
Ul miOCO •WLOIMt >u«CiUMO •» »ti» CO
FIGURE 3
SITE INDUSTRIAL/COMMERCIAL FACILITIES
VEOA ALTA SITE.VEGA ALTA.PR
SCALC 1-9000
A Hritourion Corrpany
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-2-
The Vega Alta municipal landfill is currently operating nortn
of the industrial area and is also within the public wellfield
area.- The landfill has been in operation since at least
1971 and does not employ any leachate containment or treatment
systems.
SITE HISTORY
The first indication of contamination was found in June 1983
when a survey of public water wells made by the U;S. Geological
Survey (USGS) detected 574 parts per billion of trichloroethylene
in the Ponderosa public supply well. Other volatile organics
were detected at lower concentrations.in other wells in the
wellfield systems and groundwater contamination was suspected.
In September 1983 the Vega Alta Site was placed, by EPA, on the
National Priorities List of known or threatened releases.
Ponderosa and Well GE 1 were shut down by PRASA because of
contamination in June and August of 1983, respectively. This
shut down caused a potential water supply shortage in Vega
Alta, however, PRASA constructed well Bajura 3 to eliminate
the shortage. The EPA Technical Assistance Team (TAT) initiated
sampling^in S_eptember 1983 which continued until March 1984.
Analytical results over this 16 month period indicated that
the groundwater volatile organic contaminant plume had not
significantly migrated and had been substantially reduced in
average concentration. The public wellfield operation,
including a number of private wells, has effectively contained
the contaminated groundwater and has removed contaminants by
pumping.
The EPA TAT also made site visits to the industrial plants in
October 1983 and provided general descriptions of hazardous
substance usage and hazardous wastes disposal practices.
Three potentially responsible parties were identified and
Notice Letters were sent by the Agency to those companies on
July 27, 1984. None of the companies indicated a willingness
to voluntarily undertake the response actions outlined in
EPA's July 1984 Notice Letter.
A federally-funded Remedial Investigation and Feasibility
Study was initiated at the site in April 1984 by the NUS Corpora-
tion assisted by the United States Geological Survey (USGS).
USGS performed drilling, soil sampling, and monitoring well
construction under an interagency agreement with the EPA.
In 1984 P.RASA constructed an air stripper at the Ponderosa
Well. From approximately September 1984 to May 1985, the
stripping unit was operated on a test basis to evaluate its
treatment efficiency. During the early phases of operation,
the stripper was approximately 98.6 percent efficient in
removing tetra and trichloroethene. The unit discharge was
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-3-
to Honda Creek. However, scaling problems apparently arose
which reduced the mass transfer capacity of the stripper.
The stripper operation has been stopped since May 1985 and
the Ponderosa Well is inoperative.
REMEDIAL INVESTIGATION
The Vega Alta Site Remedial Investigation (RI) was performed
from April 1984 to March 1985. The final RI Report was
submitted to EPA in May 1986. The objectives of the RI were
geared to characterize the hydrogeologic system, determine
the extent and type of hazardous substances in groundwater,
make a preliminary assessment of potential contamination
sources and evaluate the migration potential of contaminants
from the ground surface to the water table.
Groundwater analyses were performed on 168 samples from 23
wells. Groundwater sample locations are shown on Figure 4.
Volatile organic compounds were identified as the contaminants
of highest concentrations and potential public health risk.
These compounds and their frequency of detection are shown on
Table 1. These results confirmed the analytical work of the
Puerto Rico Department of Health and EPA TAT investigations
performed prior to the RI.
The analytical results obtained indicates that the groundwater
volatile organic contaminant plume has not significantly
migrated and has been substantially reduced in average concen-
tration. The pumping of the public wellfield, along with a
number of private wells, has effectively contained the contam-
inated groundwater and has removed contaminants from the
aquifer by pumping.
Volatile orgahics are decreasing over time in most of the
wells in the center area of the plume. Slight increases in
concentrations are occurring along the north and northwest
areas of the plume fringe, which indicates a slow migration
toward other actively pumping wells.
The volatile contaminant plume has been estimated to have
been reduced 58 percent in average concentration and 62
percent in contaminant mass over the 16 month sampling period.
The groundwater contaminant plume character is not consistent
over its total area. Trichloroethylene has been detected
throughout the entire plume area, however, tetrachloroethylene
and 1,1,1-trichlorethane are found predominantly in the western
portions of the plume.
The PRASA water distribution system consisting of eight active
wells, Vega Alta 1 and 2, Bajura 1 and 2, General Electric 1
and Maguayo 2, 3 and 4, was sampled at six tap locations in
the Vega Alta area. These locations are shown on Figure 5.
A total of 62 distribution system samples were taken at a
—•sr^-rr-r-i-r-;v:—:-;'.-'---^'--^^-^'- ;>7"-^"^^
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SAMPLE SUMMARY
•ASE MAP IS A PORTION OF THE U.S.O.S. VEOA ALTA.PR OUADRAMLC (7.9 MINUTE SERIES I»«T, PHOTOREVISEO Itlt I
CONTOUR INTERVAL 10 METERS.
GROUNDWATER SAMPLE LOCATIONS
VEGA ALTA SITE. VEGA ALTA . PR
SCALE-1:20,000
Soolt MUM
Regadtrt
Foreit SUr
Monterrey II
f
Bajura III
Bajura II
Pond* roil
GE II
GE 1
GE Bl
GE III
GE BUI
Vega AUi 1
Vega Alt! II
Owni-llllnols
Harm 1
Harm II
TOM to
Toaato II
PI
P2
PJ
P4
PS
NUS llMber
GW-
017
OZS
024
015
016
036
019
018
032
033
038
021
022
040
028
034
031
03S
001
002
003
030
039
Description
PRASA Do. 48-A
PRASA Hell No. 48 '
Prlvitt Mil
PRASA Hell Ho. 68-A
PRASA Melt Ho. 69
PRASA Ucll Mo. 70
PRASA U>ll No. 71
PRASA Kill lo. 72
PRASA Hell Do. 75
Private Mil .
Private Ml!
PRASA fell Ho. 78
PRASA Hell No. 79
Private Hell
Private Hell
Private Hell
Private Hell
Private Well
EPA Honltortng Hell
EPA Honltorlng Hall
EPA Honltorlng Hell
EPA Han) taring Hell
EPA Honltorlng Nell
LEGEND
^ EXISTING WELL - SURVEYED LOCATION
© EXISTING WELL - APPROXIMATE LOCATION
PRASA PUERTO RICO AQUEDUCT • SEWER AUTHORITY
IQOO p BCKIiOOO MOO 00 f CCT
.3 0 I KILOMETER
FIGURE A
IMUS
CX3RPORATC)r\J
1
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TABLE 1
VOLATILE COMPOUNDS AND FREQUENCY OP
DETECTION IN GROUNDWATER
1
Coapound
Methylene chloride
1 , 1-Dichloroethene
1 , 1-Dichloroethane
1,2-dichloroethene
1, 1,2-Tr ichloro tri floor oe thane
1,2-Dichloroethane
1 , 1 , 1-Tr iehlor oe thane
Triehloroethene
Benzene
Tetrachloroethene
BroaoCora
ChloroCora
2-Butanone
1 , 2-Dichloroprop*ne
Toluene
Acetone
Saaples
Analyzed
168
168
168
168
140
168
168
168
168
168
28
28
28
28
28
28
Samples
Detected
14
77
65
89
18<«)
17
42
145
9
81
2(t>)
6(b)
l(b)
6
-------
O/4MOOm TO SOUTHWEST)
V .
S »' I N ft S A-.-. >.'.' ' -
. .>~.~j± 'KS'7iSJ •.'••=*• 'r.7
-'' ''-SI -..:• •'•
BASE MAP ISA MMTION V TNC US.a.1. VCOA ALT A, M QUAMANM.! (7.9 MINUTE KMII IM>, PHOTOMEVIKO IM2)
t
WATER DISTRIBUTION SYSTEM SAMPLE LOCATIONS
VEGA ALTA SITE. VEGA ALTA. PR
SCALE Ii20,000
HUTU QISTHmmOU 1TSTCT ami MHWIT
MS ^labor 0»itr1ptlo>
Up«l Mr
llvltrt Fully
HMlth CtnUr
Pol let SUtlM
vtgi A1U Tow (toll
San AntMlo Hlgk School
OW-
011
014
020
021
026
027
MAM ttaUr OIltrlbutlM SytUB
PRASA Hitor OlitHbutlM SyiUa
PHASA ItaUr DIHHbutlm Syittn
PRASA UtUr OUtrtbutloa Syttai
PRASA HiUr DUtrlbutlM SysUa
MUSA Mitor Oittrlbutloa SytUo
NOT* tU «ff>CNOK-A nM*M*POr TMC MAM WE* OltTIIIBUTION fTITCM.
- PUCKTO MICO AQUEDUCT • ttMM.AUTHOMTV
1000
.5
0 OOP »00 MOO 40C3 FEET
0 IKKDMETER
FIGURE
t4
CORPQRATON
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-4-
frequency of once per month during the RI. The volatile
organic analyses performed on water distribution system
samples taken from May 1984 to January 1985 indicated that 15
compounds were detected at least one time in at least one
sample. These compounds and their frequency of detection are
shown on Table 2.
The water distribution system sample analyses indicate that
the volatile compound most frequently detected and at the
highest concentration is trichloroetheae. The next mqst
frequently detected compounds are tetrachloroethene, 1,1,1-
trichloroethane, 1,1-dichloroethene, and 1,2-dichloroethene.
These four compounds and trichloroethene are also five of the
six most detected compounds in groundwater (which includes
1,1-dichloroethane). This agreement between the compounds
detected in groundwater and the distribution system is expected
because the tap waters in Vega Alta are essentially withdrawn
directly from groundwater. Volatile organic compounds
concentrations in the distribution system were below action
levels for a removal action, therefore no action was
undertaken.
-» • RISK ASSESSMENT
The primary exposure mechanism and subsequent public health
risk at the Vega Alta Site is attributable to the ingestion
or other domestic use of contaminated groundwater distributed.
through the PRASA system. Although the primary exposure
route at the Vega Alta Site is through ingestion of groundwater,
other exposure mechanisms such as inhalation of volatile
components during showering and dermal contact during bathing
also exist. This section will present the potential for
carcinogenic and noncarcinogenic human health risks associated
with exposure to groundwater contaminants through ingestion;
the major exposure route (NUS, May 1986).
The major contaminants detected in the groundwater are volatile
organics. As a class, volatile organics are soluble in water
and do not display a marked tendency to adsorb to soil particles,
therefore, they will continue to migrate via groundwater
advection. For most of these compounds, chemical and biological
processes are unlikely to attenuate the observed concentrations
to a large extent. Reductions of concentrations will occur
primarily through dispersion and dilution.
Noncarcinogenic Risks
Noncarcinogenic effects associated with ingestion of groundwater
were examined through comparison of the observed concentrations
to the USEPA Drinking Water Health Advisories and reference doses.
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TABLE 2
VOLATILE COMPOUNDS AND FREQUENCY OP
DETECTION IN WATER DISTRIBUTION SYSTEMS
Compound
Methylene chloride
1 , 1-Dichloroethene
1, 1-Dichloroe thane
1, 2-dichloroethene
1, 1,2-Tr ichlorotr ifluoroe thane
1,2-Dichloroethane ' . •.
1,1,1-Trichloroe thane
Triehloroethene
Benzene
Tetrachlozoethene
2-Buta»one
Broaoform
Chloroform
Bronodichlorome thane
Oibroaochlor one thane
Sample!
Analysed
62
62
62
62
16
62
62
62
62
62
8
8
8
8
8
Samples
Detected
3
41
30
40
,<*)
3
48
61
3
55
Kb)
2(b)
2(b)
l(b)
l(b),
Percent
Detected
4.8 *
66.1
48.4
64.5
56.3
4.8
77.4
94.4
4.8
. 88.7
v 12.5
25
25
12.5
12.5
Maximum
Concentration
(ppb)
2.9/26{c)
27
5
6
17.1
2.7
7
42
2.5<0
10
16
3/4. l(C)
7
6
6
(•) Detected by MUS field GC onlj.
(b) Detected bj EPA CLP onlj.
(O ote data with caution, possibly blank or lab contamination.
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-5-
Maximum observed concentrations in samples from monitoring
wells, PRASA supply wells, and taps do not exceed applicable
values for gauging noncarcinogenic effects. Therefore, no
threshold health impacts are anticipated through groundwater
ingestion.
Carcinogenic Risk
Organic contaminants detected in .well samples that are known
or suspected carcinogens (i.e., no known threshold below
which toxic effects would not occur) are shown in Table 3.
The table below includes estimated lifetime cancer risks
associated with ingestion of the contaminants found in resi-
dential tap water samples and PRASA well samples. Lifetime
cancer risks are based on calculations using the carcinogenic
potency factors reported in the Superfund Public Health
Evaluation Manual (USEPA, October 1986b).
Risk estimates were calculated for the mean, minimum, and
maximum groundwater concentrations to provide a range of risk
estimate*. The actual exposures are those concentrations
noted in the tap water samples. Receptors are not exposed to
the concentrations observed in the PRASA well samples because
of dilution that occurs in the water system.
To assess the total risk~posed by the presence of more than
one known or suspected carcinogen, risk estimates calculated
for single contaminants are added (USEPA, October 1986b) .
The total potential carcinogenic risk to residents associated
with ingestion of the current water supply is:
For
For
For
Minimum Concentration
Mean Concentration
Maximum Concentration
/
Risks
Tap Water
1.1 x 10-5
(1 in 89,000)
4.0 x 10-5
(1 in 25,000)
1.5 x 10~4
(1 in 6,700)
PRASA Wells
1.3 x 10-5
(1 in 77,000)
1.1 x 10"*
(1 in 9,000)
7.6 x 10-4
(1 in 1,300
-------
TABLR 3
RISK ASSOCIATED WITH INGBSTION OP CARCINOGENS
VBGA ALTA SITE
Contaminant
>
Tetrachlocotthtna
TrlcMoro*th«nt
l.l-Dlchlorocthana
I.J-Dlchloroatbana
••ntana
Total mtk
CarclrtO9aalc MUk/Mnoa
•.•tidtntlal Tap Matte
Ninlaina
Concentration
1.1 • 10 «»1.J uq/l
1.1 m IO-'tJ.l 09/1
4.2 • IO-*«I.f oa/l
l.i a lO'Ml.l ag/1
».» * IO-TIO. 4 «a/i
l.l • li-'
Mean
Concentration
4.1 • 10-**4.t uf/l
«.• * 10-»«l«.« ««/!
2.1 • 10-»«4.7 uo/l
4.1 • 10-*|1.» Uf/l
>.• • I0-»|l.ll •«/!
4.« • !•-»
NtlUuii
Conontf atloa
1.0 • 10-^*10 ug/1
l.f « I0-*t)2 uq/1
I.I • 10-<«1T ug/1
4.» • 10-«f2.7 u«/l
l.f a H-»t2.1 uf/1
I.S a 10-*
PMSft N«.li
MlnUun
Concanti atlon
1.0 • 10-6il.OZ uq/1
C.O a 10-ofl.l ug/l
l.T • 10-o«0. M ug/l
1.0 • 10-«ll.l u«/l
*
1.1 a 10-*
«,v
Cpnccntc-t Ion
1.1 a 10-'*; if u,/i
2.* a 10 '*•-.» ug/l
S.I » IO-»« '.4 uo/l
1.1 a 10-*««. 4 U9/1
•
1.1 a 10-4
NaalauiH
Concantcatlon
1.1 a 10 •*»J1 U9/1
4.1 a I0-«»i>7 U9/1
1.0 « 10-4*41 U9/1
4.7 « lO-ffll ug/l
S.4 a I0-«t2.1 an/I
».4 a 10 •
• Beniene «•• d«t«ct»d only one*. th«r«for«, the rl>k «•• pr4»«nt«d ao a moxinun concentration In c der to present a
"worat case* scenario. /
-------
-6-
Environmental Impacts
Based on the existing chemical-analytical data base and
hydrogeologic conditions, no adverse environmental impacts
are anticipated as a result of contaminant migration from the
Vega Alta Site. Because of the complex hydrogeological
conditions (i.e., groundwater flow in a Karst environment), it
is not possible to model plume migration. Therefore, the
conclusion regarding environmental impacts is based primarily
on engineering judgment and experience. The primary discharge
points for .contaminated groundwater (in the absence of pumping)
are the Prieta Marsh and the Atlantic Ocean. It is not expected
that present or future contaminant loading to the marsh or the
ocean will adversely affect environmental receptors. The
marsh discharge point is approximately 3 miles from the
Ponderosa Well. Pumping of the well field controls plume
migration to a great extent. Further, in view of the even
greater groundwater molecular diffusion, and other natural
attenuation mechanisms, it is doubtful that measureable
concentrations will extend to the discharge areas.
^ 'ALTERNATIVES EVALUATION
The remedial alternatives for the Vega Alta Public Supply
Wells Site were developed and evaluated using the Comprehensive
Environmental Response, Compensation and Liability Act of
1980, as amended by the Superfund Amendments and Reauthorization
Act of 1986 (CERCLA), the National Oil and Hazardous Substances
Pollution Contingency Plan (NCP), 40 CFR §300.68, and the
"Guidance on Feasibility Studies Under CERCLA" as guidance.
The major objective of the FS is to evaluate remedial alterna-
tives using' a cost-effective approach consistent with the
goals and objectives of CERCLA. According to Section 121 of
CERCLA, the recommended remedial alternative should protect
human health and the environment, should be cost-effective,
and should utilize permanent solutions and alternative treat-
ment or resource recovery technologies to the maximum extent
practicable. The proposed remedy must also attain applicable
or relevant and appropriate federal and state public health
and environmental requirements (ARARs) that have been identified
for the site (see Tables 4,5 and 6). Section 300.68(e) of the
NCP outlines procedures and criteria which are used in selecting
the most cost-effective alternative.
-------
TABLK A
APPLICABLE, OR RELEVART MID APPROPRIATE REQUIREMENTS
V1CCA ALTU SITE
VEGA JiLTA, PUERTO RICO
GROURDMATER
Chum ical
benxene
toluene
tetrachloroethene
trichloroethene
1,2-dichloroethene
1 , 1-dichloroethene
1 , 1, 1-trichloroethane
1 , 1-d ichloroethane
1 , 2-d ichloroethane
nethylene chloride
Maximum
Observed* *>
Concentration
(M9/1)
7.5(M) ,
24
(M9/U
(0.«7)
15,000
CO. 88}
<2.t)
—
CO. 033}
—
—
—
10.191
I'
Health
Jldvisory(5)
(V9/D
—
2,420
5.00CI
—
70
7
200
—
2.600(C)
—
Reference
Do..(*>
(M9/U
—
10,500
700
—
—
315
18,900
4,200
—
2,100
Puerto Rl«:o
Beallih .
DepartMent':7)1
IP9/HI
5
—
50
—
—
— .
1,000
—
10
150
Risk-Baaed
tlO-«)<»l
lug/i)
•MHBMMMBi
0.7
KA
0.7
2.8
: RA
0.23
MA '
RA
RA '
RA
(1)
(2)
(3)
(«)
(5)
(*)
j(7)
<«)
Values in
M - Detected in awnitoring well s«q»le. S - Delected i.n PRASA supplj w»ll
MaxLaum Contaminant Level Goal (DSKPA, Rovenfaer, 1985). P - Pro|M»ed v<»lue.
NaxiBum Contaainaot Level (OSRPJk, July, 1987). C - Chronic expoimre {!««• than lifetioe).
Ambient Water Quality Criteria fOSKPA, October, 19B6b). Adjusted fi»r drinking water only.
parentheses correspond to Midpoint of cancer risk rangu (lfl~') for an individual contaminant.
EPA Drinking Hater Health Advisory (USBPA, Narch, 198V). Value • presented are for lifetime (70- year) exposure
unless otherwise noted. C - Chronic exposure {less thun lifetime)*
Formerly Acceptable Daily Intake; {DSKPA, October, 1986ti). Valueii presented are for oral exposure. Converted to
concentrations by assuming ingest ion of 2 liters/day arid a body ireight of 70 kg.
Administrative Order Number 1O {see Appendix D).
Values presented are for a cumulative risk of 1x10-6 (see Appendix D for calculations). Values presented for
pervasive (frequently detected) carcinogens. RU - Hot applicable. Value* revised according to lin«l rendition
of Ktandards and Health Advisory Chart, USEPA, 9-9-87.
-------
TABLE 5
APPLICABLE, OR RELEVANT AND APPROPRIATE REQUIREMENTS - SURFACE WATER
VEGA ALTA SITE
VEGA ALTA, PUERTO RICO
Chemical
benzene
toluene
tetrachloroethene
trichloroethene
1,2-dichloroethene
1,1-dichloroethene
1,1,1-trichloroe thane
1 , 1-dichloroe thane
1,2-dichloroe thane
1,1,2-trichlorotrifluoroethene
methylene chloride
MPDES
Permit
(vg/iM1*
luu
100
10
50
10
10
10
100
100
100
100
AWQC(2)
Aquatic Life
(wg/i)
j.3xij3
1.75x10*
5.28x103
4.5x10*
1.16x10*
1.16x10*
1.8x10*
MA
1.18x105
NA
l.lxW*
AWQCO)
Human Health
(pg/D
•.
-.0*
4.24x105
8.85*
80.7*
NA
1.85*
1.08x106
NA
243*
NA
15.7*
(1)
(2)
(3)
*
NA
Effluent limitations established on pages 5 and 11 of the National
Pollutant Discharge Elimination System (NPDES) permit issued for
Ponderosa stripper effluent (Appendix B).
Ambient Water Quality Criteria for the protection of freshwater
aquatic life (USEPA, November, 1980).
Ambient Water Quality Criteria for the protection of human health
through the ingestion of aquatic organisms (fish) (USEPA, November,
1980).
Value corresponds -to a carcinogenic risk of 1 x 10~*.
Not Available.
-------
TABLE 6
APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS
VEGA ALTA SITE
VEGA ALTA, PUERTO RICO
- AIR
Chemical
benzene .
toluene
tetrachloroethene
trichloroethene
1 , ?-4ichloroethene
1 , 1-dichloroethene
1,1, 1-t r ichloroethane
1 , 1-dichloroethane
1 , 2-dichloroethane
methylene chloride
TLV (STEL)
(mg/m3)(D
75
560
1,340
1,080
1,000
80
2,450
1,010
NR(2)
1,740
TLV (TWA)
(mg/m3)
•30
375
335
270
790
20
1,900
810
40
350
(l) Source: ACGIE, 1986
(2) NA - Not Available
-------
-7-
A five step process was developed and used to meet the FS
objectives. The following is a summary of that process.
The first step is to evaluate human health and environmental
effects associated with releases and threatened releases of
hazardous substances from the site. Criteria to be considered
are outlined in Section 300.68(e) of the NCP and include such
factors as actual or potential direct contact with hazardous
material, degree of contamination of-drinking water, and
extent of isolation and/or migration of the contaminants.
*
The next step is to develop a range of potential available
remedial technologies that could be used to remediate the
site. Remedial technologies where treatment permanently and
significantly reduces the toxicity, mobility or volume of the
hazardous substances as a principal•element, are to be preferred
over remedial technologies not involving such treatment.
These technologies are initially screened on a technical
basis. Based on the screening, a list of individual remedial
technologies appropriate to site conditions and consistent
with the remedial action objectives is developed.
The si^^-appropriate remedial technologies are then combined
into a number of preliminary remedial alternatives. The
basis for the various combinations are: the technical and
logical interrelationship between separate technologies;
Section 300.68(f) of the NCP requirements regarding the
general categories of alternatives which must be considered
and CERCIA Section 121-provisions regarding the preference
for remedial actions that utilize permanent solutions and
alternative treatment or resource recovery technologies.
USEPA is in the process of revising the NCP to reflect these
new provisions added by SARA. USEPA1 s "Interim Guidance
on Superfuhd Selection of Remedy" memorandum, issued December 24,
1986, is intended to aid the Agency in the selection of
remedial actions pending USEPA's upcoming revisions of the
NCP. This summary reflects that guidance. USEPA1 s interim
guidance requires analysis of alternatives involving: 1)
treatment options; 2) containment of waste option with
little or no treatment, but providing protection of human
health and the environment primarily by preventing exposure
or reducing the mobility of the waste and 3) the no-action
alternative. These three categories of alternatives must be
carried through the detailed evaluation process, but for the
Vega Alta Site, groundwater containment .alternatives have not
been included. These are not considered feasible and will not
be evaluated in the prescreening. The reasons for exclusion
of these alternatives are related to the site hydrogeologic
conditions.
-------
-8-
The fourth step in the process is to provide an initial
screening of these alternatives as delineated in Section
300.68(g) of the NCP. The three broad criteria that should
be utilized in the screening are: the relative effectiveness
in minimizing threats; the engineering feasibility of the
alternatives; and the cost of 'implementing the remedial action.
Treatment options and the no-action alternative should be
carried through this step. This general screening is intended
primarily to reduce the number of remedial alternatives which
will subsequently be evaluated in detail.
The final step as outlined in Section 300.68(h) of the NCP is
to conduct a detailed analysis of the limited number of
alternatives that remain after the initial screening. A
treatment, containment, and no-action alternative should be
included in this analysis. For each alternative, the following
factors, as appropriate, are to be considered:
0 An evaluation in terms of engineering implementation,
reliability, and constructability;
0 An*assessment of the extent to which the alternative is
expected to effectively prevent, mitigate, or minimize
threats to, and provide adequate protection of human
health and the environment. This includes an evaluation
of the extent to which the alternative attains or exceedes
ARARs for the site. Where the analysis determined that
federal and state human health and environmental
requirements are not applicable, or relevant and appropriate,
the analysis, as appropriate, evaluated the risks of the
various exposure levels projected or remaining after
implementation of the alternative under consideration;
0 An analysis of whether recycle/reuse, waste minimization,
waste biodegradation, destruction, or other advanced,
innovative, or alternative technologies is appropriate
to reliably minimize present or future threats to human
health and the environment;
0 An analysis of any adverse environmental impacts and
methods for mitigating these impacts, and costs of
mitigation;
0 A detailed cost estimate, 'including operation and
maintenance costs, and distribution of costs over time.
This includes a cost comparison of alternatives within
each category.
-------
-9-
DEVELOPMENT OF ALTERNATIVES AND INITIAL SCREENING
Remedial response for the Vega Alta Public Supply Site will
address the management of contaminated groundwater as the
first Operable Unit since it is considered critical for
protection of- public health and reduction of risks associated
with ingestion of the groundwater. Source control actions
are considered less critical from a public health standpoint
and will be addressed at a later date once additional source
investigations are completed.
The effect of undefined source conditions on the performance
evaluations of groundwater remedial alternatives is not
expected to be critical over the long term because of two
reasons:
0 Groundwater remediation is estimated to require a longer
time period than source control, which can be accomplished
early in the lifetime of the groundwater restoration
period. Delay of source control actions for a short
time is not expected to significantly affect the ultimate
time period required for cleanup of the groundwater.
0 The groundwater plume has been shown to be decreasing in
contaminant mass and average concentration based on the
RI data collected from September 1984 to January 1986.
This may suggest that the source of groundwater contami-
nation has either been eliminated or has decreased
significantly from the period prior to September 1984.
However, since the sources are not fully identified and
no significant source control is known to have occurred
at nearby facilities significant further RI work is
necessary before the trend can be substantiated.
The objectives of the remedial actions being -evaluated are
restoration of the aquifer, management of migration of contam-
inants in the groundwater system and protection of the public
from adverse health impacts through groundwater ingestion.
Criteria established to obtain these objectives are:
0 Reduce contaminant levels in the groundwater.
0 Protect uncontaminated groundwater for present/future use.
0 Reduce contaminant levels at the tap to prevent unacceptable
human exposures.
These objectives are based on the baseline risk assessment
and on review of Applicable or Relevant and Appropriate
Requirements (ARARs) and USEPA Draft Guidance for Remedial
Actions for contaminated Groundwater at Superfund Sites
(USEPA, October 1986).
-------
-10-
the Vega Alta Site remedial technologies were pre-screened
technical suitability. The pre-screening criteria included
the following:
For
for
Implemen.tability -
cleanup.
construetability and time to achieve
Applicability - physical
site conditions.
and chemical suitability for
Technologies that are not considered appropriate for utilization
at the Vega Alta Site and a brief discussion of the reasons
for their exclusion are listed in Table 7.
Table 8 lists and briefly describes the technically
appropriate remedial technologies for" the Vega Alta Site.
These technologies 'were accepted on the basis that they are
compatible with the specific site conditions and the remedial
action objectives for this operable unit. These technologies
were then assembled into alternatives. As a result, four
remedial action alternatives as specified in Table 9, were
developed for evaluation.
The four remedial alternatives have been subjected to an
initial screening consistent with 40 CFR Section 300.68 (g) (1) ,
(2) and (3) of the NCP to narrow the list of potential remedial
actions for further detailed analysis.
-------
-11-
TABLE 7
Inappropriate Remedial Technologies
In-situ Treatment
0 Biodegradation - Biodegradability of the existing
levels of chlorinated aliphatics has not been adequately
established, especially for aquifer restoration requiring
risk levels of 1X10-4. The contaminated groundwater zone
is currently in use as a major portion of the public
water supply to Vega Alta and cannot be taken out of use
without supplying alternate water.
0 Vacuum Extraction - Vacuum extraction technologies
have been demostrated on a limited basis for the removal
of volatiles from the unsaturated zone, ^plications
for volatiles renoval from the groundwater zone have not
been demonstrated based on available literature. The
application to saturated zone volatile removal is expected
^"to be- conceptually infeasible because of problems with
withdrawal of groundwater into extraction wells and the
limited stripping efficiency available because of the
relatively small air to water surface interface area
compared to other technologies, such as conventional air
stripping towers.
Offsite Groundwater Treatment
0 Publicly-Owned Treatment Works (POTW) - The wastewater
treatment plant in Vega Alta, located away fron the site
is operating above design capacity and cannot accept
additional discharges. The projected well discharge
rates, even for one of the public wells, exceeds the
existing design capacity of the POTW. Because of hydraulic
loading constraints of the POTW, this technology is not
applicable to handle the treatment of contaminated
groundwater.
Tap Water Treatment
0 Boiling-Mixing-Aeration - Although sich a treatment
approach is technically feasible, it would require that
all residents employ them consistently. It is unlikely
that the general population will do this and such treatment
techniques are considered neither implanentable nor
reliable.
-------
-12-
TABLE 8
Appropriate Remedial Technologies
Groundwater Treatment Onsite
0 Air Stripping — This technology has been shown to be
an effective net hod of removing volatile constituents
from groundwater. It is a partitioning process in which
the volatile organic contaminants are transferred from a
dissolved state in the aqueous phase to the air phase
through a water to air transfer process. Volatile
organic removal efficiencies in excess of 99.9% can be
achieved via air stripping technology.
0 Carbon Adsorption - This technology has been extensively
used for water treatment. It is a partitioning process
in which the contaminants are transferred from a dissolved
state in the aqueous phase to the surface of a solid
phase, where they accumulate for subsequent extraction,
and/or destruction. Water is passed through a treatment
bed and the dissolved contaminants are removed frcm
solution via a physical adsorption process.
0 Pretreatment for Scaling - Problems haus apparently
been encountered during operation of the air stripper at
the Ponderosa Well in Vega Alta. It has been reported
that the stripper operates ineffectively as ? result of
scaling. Based on the nature of the aquifer at the Vega
Alta Site (calcitic limestone) it is believed that the
scaling problem is probably a result of stripping of
dissolved carbon dioxide from the groundwater. Sodiuti
hexanBtaphosphate pretreatment has been selected as a
cost effective method of preventing calcite precipitation.
Bench and pilot-scale studies will be required to
determine material requirements and to demonstrate the
effectiveness of the method prior to completing the
remedial design.
Alternate Water Supplies
0 New Wells - An alternate water supply yielding approxi-
mately 2,250 gallons per minute (gpm) must be provided
to replace the cumulative supply which will be lost by
eliminating the Ponderosa, GE-1, GE-2 and the Bajura 3
wells fron the PRASA water supply system in Vega Alta.
0 Surface Water - Surface water supplies are available
for public water use in the Vega Alta area. The two
principal streams in the site area, Rio de La Plata and
Rio Cibuco, have sufficient base flows to provide a
significant source of water for public use.
-------
-13-
TABLE 9
Preliminary Remedial Action Alternatives
Alternative Number Description ..
1 No action with site monitoring.
2 Groundwater Treatment with
discharge into PRASA Distribution
System (PRASA wells Ponderosa,
GE 1, GE 2 and Bajura 3).
3 Groundwater Treatment with
Surface Discharge and Alternate
,=, . Water Supply by Surface Water
intake and New Wells.
4 • Water Treatment at Individual
Public Water Supply Taps.
-------
-14-
..; Detailed Evaluation of Alternatives
_.- As a result of the screening process, a total of three remedial
' action alternatives were developed for detailed comparative
':; evaluation at the Vega Alta Site. The major criteria for
;; evaluation of the remedy are:
1. Compliance with ARARs
': 2. Reduction of Toxicity, Mobility or Volume
i 3. Short-Term Effectiveness
1 4. Long-Term Effectiveness and Permanence
] 5. Implementability
:.\ 6. Cost
- 7. Community Acceptance
'; • 8. State Acceptance
9. Overall Protection of Human Health and the Environment
: Factors for each evaluation criteria are summarized on Table 10.
•''. The alternatives were evaluated for both short-term and long-
-,-, term considerations related to the criteria. Because of the
uncertainty in estimating the rate of restoration of the con-
taminated portion of the aquifer, the evaluation as to the
length of time required for full remediation is, of necessity,
i qualitative. These three remedial alternatives, and their
';. associated capital costs and total present worth costs are
provided in Table 11.
.'; The detailed analysis of the three remedial action alternatives
is summarized as follows:
; - Alternative 1 - No-Action with Monitoring
;• This alternative will not require any implementation of
.:: remedial actions and the level of present and future potential
J human health risks will continue unabated. Monitoring is
• proposed as part of this alternative to assess the levels of
^ public risk over time and to track the migration of the con-
• taminated groundwater. Groundwater and distribution system
tap sampling is proposed on a quarterly basis. The proposed
monitoring program includes sampling of 4 taps and 10 wells.
-•-'; The no action alternative will not reduce present carcinogenic
'•;' risks and will not comply with ARARs for drinking water
.•j quality unless contaminant levels decrease significantly
i through natural attenuation processes.
;'\ Based on historical trends as described in the RI report, the
•/: continued pumping of the existing wellfield is expected to
•'-] actively remove contaminants from the groundwater. A future
; projection of contaminant reduction based on historical data
-------
TABLE 10
EVALUATION FACTORS FOR REMEDIAL ALTERNATIVES
VEGA ALTA BITE
effectiveness
Protect Iveneas
SBORT-TIRH
Reduction of
•listing risks
Compliance with
•OMtARARS
Compliance with
s^me"'critaria.
adviaories, and
guidance
Protection of
community and
workers during
remedial action*
Time until
protection is
achieved
Reduction of
ToBlcity, Nobility,
or Volume
•. •
iMipleaientabillty
Technical '
reaalblllty
Ability to
construct
technology
Short tor*
reliability of
technology
Co»pliance vlth
•one ARARs
(primarily
action-apeeiCie)
/
Adnlnlstfativa
reaalbillty'
Ability to
obtain approval a
fro* other
agencies
Likelihood of
Cavorable
community
reaponie
Coordination
with other
agencies
CoMipl lance with
SOIM location-
spec 1C lo ARARe
Need to respond
to other el tea
(1041
Availability
Avallablll 7 of
treat*ent»
atorage, a.-.tS
disposal
aervices and
capacity
Availability of
necessary
equipment and
•pedal la t«
^
Coat
MoMedy
Oevelopawnt
and
conatruction
costs
Operating
costs for
Implementing
remedial .
action
Other
capital and
abort-tern
eoata until
remedial
action la
complete
-------
i r ii
t_.i i
I -*
' >
TABLE 10
EVALUATION FACTORS FOR REMEDIAL ALTERNATIVES
VEGA ALTA SITE
PAGE TWO
Effectiveness
Protectivcnei*
LONG-TERM
Magnitude of
residual dak
Long-term
reliability
Compliance with
•one ARAMS or TiCi
Prevention of
future eapoaure to
residual*
Poteatial need for
replacement
Reduction of
Toilcity, Nobility,
or VoluMe
•
Permanent
•ignificant
reduction of
toHiclty, nobility
or «olu*«
'*. •
I wpleMnt ability
Technical
reaaibility
Kaee of
undertaking
additional
remedial action.
if necessary
Ability to
Monitor
effectiveness of
rensdy
/
ability to
per f oral
operation and
•aintonanca
functions
Administrative
reaaibility
•
Availability
Cost
Remdy
Coats of
operation
and
Maintenance
for as long
as necessary
Costs of
5-year
reviews
Potential
future
remedial
action costs
-------
.
''
II
Table 11
KEXRDIAL ALTERNATIVE COST SUMMARY
VEGA ALtA SITI
VEGA ALT A, PUERTO RICO
Koaodlal Altornatlvo
No.l - Mo Action
MO. 2 - Groundwator TroatMont
with Dlocharoo to tho
»RASA Distribution Syato*
ft. Troat-nt at wollhoad
B. Troat»ont at control
locations
Mo. I - Croundwator Troatnont
with Curfaco Nator
Dioeharoo and Al tomato
Motor fupplios
ft. Troat»ont at oollhoad
•. Troatawnt at control*
locations
Capital
Costs
(fl.OOO)
—
4.106
4.134
6.502
6.306
Annual
OftM Costs
($1.000)
56
581
491
r
672
585
•rosont Worth Coxts (fl.OOO)
1 yoar O»H
51
4.634
4.567
7.113
6.636
9 yoar O»H
212
6.309
6.021
9.049
8.524
10 yoar OSM
344
7,677
7,194
10.631
9.902
30 yoar O*M
526
9.594
9.628
12,838
11.623
-------
-15-
might be valid if the sources(s) of contamination are remediated,
however, source characterization has not been performed and
the 'presence and degree of contaminant loading to the ground-
water cannot be determined.
Furthermore, trend analyses for groundwater concentrations
are not considered appropriate because of the complex charact-
eristics of organic contaminant migration and complications
arising as a result of hydrogeologic conditions. A verified
contaminant transport model would have enabled a reasonable
future prediction of groundwater conditions, however^ a model
is not applicable to the site because of the Karst geology.
Despite these limitations with respect to prediction of future
conditions, it is expected that average groundwater contaminant
levels will decline if the source(s) is controlled. A
reduction in tap water concentrations should occur as g.round-
water concentrations decrease.
Groundwater contamination results in a mean carcinogenic risk
of 1.1 x 10~4 and a maximum carcinogenic risk of 7.6 x 10~4
through ingestion. The mean incremental cancer risk is near
the EPA Level III groundwater remediation level of 1 x 10~4.
The ingest ion-based risk levels are expected to decline over
time, assuming that source control is implemented, however,
the restoration rate to Level III or lower levels (I and II)
cannot be determined at the present time.
The technical feasibility evaluation of this alternative is
not applicable since remedial actions are not proposed.
Ongoing monitoring of groundwater and taps is reliable for
assessment of contaminant levels and can be performed over
the long-te.rm. as required.
In addition, contaminant levels in tap water'are in excess of
the Maximum Contaminant Levels promulgated pursuant to the
amendments to the Safe Drinking Water Act and the recent
Puerto Rico Department of Health regulations.
This alternative does not address source control actions.
Insufficient site data on the source(s) is available to
identify and evaluate potential remedial alternatives for
source(s) remediation. However, the groundwater plume has
been decreasing in contaminant concentration based on the RI
data collected from September 1984 to January 1986. This may
suggest that the source of groundwater contamination has
either been eliminated or has decreased significantly from
the period prior to September 1984. .Additional investigative
studies will be conducted to fully define the source(s) of x
the groundwater contamination and evaluate any potential of
contaminants to migrate to the groundwater system at Vega
Alta.
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-16-
Alternative 2 - Groundwater Treatment with Discharge to the
PRASA Distribution System
This alternative involves treatment of 4 PRASA public supply
wells and hook-up of two private groundwater users to the
distribution system. The treated wells include:
0 PRASA Ponderosa (currently inactive)
0 PRASA GE 1 (currently inactive)
0 PRASA GE 2 (currently active)
0 PRASA Bajura 3 (currently active)
Treatment of PRASA wells' GE 1, GE 2 and Bajura 3 will be by
individual treatment systems consisting of scaling pretreatment,
air stripping, and possibly activated carbon; contingent upon the
results of pilot studies for the air strippers. Treated effluent
will be discharged into the PRASA distribution system for
public use. The efficiency and applicability of the treatment
processes will be evaluated by bench and pilot scale treatability
tests prior to final design and implementation of the specific
treatment systems.
Treatment of Ponderosa well will be by scaling pretreatment
and air ^Stripping. Discharge shall be to Honda Creek in
accordance with the existing NPDES permit; the effluent will
meet the same quality requirements as for PRASA wells GE 1,
GE 2, and Bajura 3 such that Ponderosa treated water can eventually
be utilized for water supply in the future. Activated carbon
treatment could be added to this treatment process should the
need arise.
Two treatment scenarios are considered under this alternative
and are designated as follows:
0 Alternative 2A. Individual treatment un'its at each of 4
PRASA wells.
0 Alternative 2B. Central treatment unit for 3 PRASA
wells, Ponderosa, GE 1, GE 2, and an individual treatment
unit for PRASA Bajura 3 well.
A typical treatment process for each alternative is shown on
Figure 6. The general arrangements of Alternatives 2A and
2B are provided on Figures 7 and 8, respectively.
With the installation of this treatment system, the existing
public health risks from ingestion would be reduced to levels
below 1 x 10~6. Treatment of wellwater to levels below the
1 x 10~*> ingestion risk level will meet all Federal and State
ARARs. The treatment systems are expected to be reliable and
provide long term mitigation of the human health risks assuming
proper operation and maintenance of the systems. Pretreatment
units for scaling control are proposed for each treatment
system to minimize maintenance due to mineral deposition
within the air strippers. Carbon columns might require per-
iodic replacement to supply fresh carbon, however, shut down
-------
TftCAtMCNT SVmU POft f ACM ALTIRNATTVt
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VEGA ALTA SITE. VEGA ALTA. PR
-------
•AJUftA 5
SCALE IN MtYKMS
REMEDIAL ALTERNATIVE No. 2A GENERAL ARRANGEMENT
VEOA ALTA SITE. VEGA ALTA. PR
-------
•AJUMA 9
O tBO
•CAIC IN MCTIAS
FIGURE 8
REMEDIAL ALTERNATIVE No.2B GENERAL ARRANGEMENT
VEGA ALTA SITE. VEGA ALTA. PR
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-17-
time would be minimal and is not expected to cause a significant
shortage in water supply. Preliminary estimates indicate
that carbon unit life for Al-ternatives 2A and 2B is 19 years
at an assumed influent volatile concentration of 20 ppb. At
this rate, shut down time of the carbon columns for replacement
is expected to be negligible over the life of the system.
The design of. the air stripper and carbon adsorption units
should be supported by bench-scale treatability testing.
The bench-scale testing will also include additional ground-
water sampling to establish sizing and design parameters.
Sampling will continue throughout the implementation of this
.remedy. These tests will confirm the treatability of* the
groundwater using these treatment processes and will determine
specific design requirements.
This alternative will meet the reduction of toxicity, mobility
or volume criteria due to the fact that it would involve
active removal of the groundwater contaminants at a rate
exceeding the present wellfield pumping rate. Operation .of
the wellfield will also minimize migration of contaminants to
regional downgradient areas to the north by containing
contaminants within a local drawdown area.
The comgpnent technologies proposed for groundwater treatment
are all demonstrated and commercially available. These
technologies are expected to be technically feasible and
readily implementable.
Cost estimates have been performed in detail for each of the
remedial alternatives. These estimates are summarized on
Table 11. Present worth costs have been estimated for a
range of operation and maintenance periods. These are 1, 5,
10, and 30 years.
This alternative does not address source control actions.
Insufficient site data on the source(s) is available to
identify and evaluate potential remedial alternatives for
source(s) remediation. However, the groundwater plume has
been decreasing in contaminant concentration based on the RI
data collected from September 1984 to January 1986. This may
suggest that the source of groundwater contamination has
either been eliminated or has decreased significantly from
the period prior to September 1984. Additional investigative
studies will be conducted to fully define the source(s) of
the groundwater contamination and evaluate any potential of
contaminants to migrate to the groundwater system at Vega
Alta.
Alternative 3 - Groundwater Treatment with Surface Water
Discharge and Alternate Water Supplies
This alternative involves treatment of groundwater at four
PRASA wells with discharge into surface water bodies to
contain the contaminant plume. Two private groundwater users
will be hooked-up to the distribution system. Alternate
water supplies will be provided to make up the shortage
caused by removing two active public wells from service.
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-18-
The wells proposed for treatment include the following:
0
0
PRASA Ponderosa (currently inactive).
PRASA GE 1 (currently inactive).
PRASA GE 2 (currently active).
0 PRASA Bajura 3 (currently active).
The alternative water supply will be a combination of surface
water and groundwater, The 4 new wells are considered
permanent water supply sources. The surface water treatment
system is considered a temporary installation that will
operate over the period of groundwater remediation.
Two treatment scenarios are considered under this alternative
and are designated as follows:
0 Alternative 3A. Individual treatment units at each of 4
PRASA wells.
0 Alternative 3B. Central treatment unit for 3 PRASA
wells: Ponderosa, GE 1 and GE 2 and an individual treat-
ment unit for PRASA Bajura 3 well.
A typical tre'atment process for each alternative is shown on
Figure 6. The general arrangements of Alternatives 3A and
3B are provided on Figures 9 and 10, respectively.
This alternative will be effective by reducing existing public
health risks from ingestion to levels below 1 x 10~6 by removal
of 2 active contaminated wells from the public supply system
and supplementing the water supply with uncontaminated alter-
nate water. Alternate water supply provided by 4 new wells
and a surface water intake at Rio Cibuco are expected to
provide water/of suitable quality to meet drinking water
ARARs over the long-term.
Pumping of the existing wellfield plus reactivation of two
inactive wells (Ponderosa and GE 1) would involve active
removal of the groundwater contaminants at a rate exceeding
the present wellfield pumping rate. The start up of the
Ponderosa well, in particular, will remove considerable
contaminant mass since this well has historically been in the
area of highest plume concentrations.
Operation of the wellfield will also minimize migration of
contaminants to regional downgradient areas to the north by
containing contaminants within a local composite drawdown area.
Ongoing downgradient monitoring will be required to assess
migration of contaminants from the pumping wellfield area.
Because of the inherent complexities of the Karst hydrogeologic
system, there is potential for migration of contaminants to
-------
•AJUHA 5
TKKATNKNT UNIT
•UNffACf WATW IMTAKC
TNCATMIMT •VtTMl
•CNCMAL MIA MOfOSCO fOR
INSTALLATION Of NIW MUNICIPAL
WATtH SUfftV WILLS SIC PM.S-S ,
' VEGA ALTA
SCALK IN MCTCM9
REMEDIAL ALTERNATIVE No. 3A GENERAL ARRANGEMENT
VEGA ALTA SITE. VEGA ALTA. PR
-------
•MUM* 3
REMEDIAL ALTERNATIVE No.3B GENERAL ARRANGEMENT
VEGA ALTA SITE. VEGA ALTA. PR
10
-------
-19-
downgradient areas, although this has not been observed to
date in the wells beyond Monterrey 2, which is in the regional
downgradient direction.
The wellfield pumping will ultimately result in restoration
of the groundwater to a Level I remediation quality assuming
the source(s>- is controlled, however, the time rate of restoration
cannot be determined at this time.
Air stripping represents a long-term solution assuming proper
operation and maintenance. The pretreatment units for scaling
reduction will help maintain stripper treatment efficiency
over the long term. Public health risks from short-term
breakdowns in treatment efficiency are expected to be negligible
since the stripper discharge shall not be into the water
distribution system.
Demonstrated treatment efficiencies of up to 98 percent at
the Ponderosa well (historically the most contaminated well)
indicate that air stripping will readily meet the surface
water discharge limitations set for Honda Creek. The other
wells have historically lower contaminant levels than Ponderosa.
Air stripping at these wells is expected to be more reliable
for attainment of effluent limitations, assuming similar
NPDES levels are issued for these discharges.
Treatment of surface water for potable use employs conventional
treatment processes that have been demonstrated and are
readily available. The ability of Rio Cibuco to supply 1145
gpra over the period of groundwater remediation is considered
feasible based on the reported minimum 7-day consecutive flow
rate of 3816 gpm. The minimum 1-day recorded flow at Rio Cibuco
is 3322 gpm. A severe drought would necessitate reduction of
withdrawal rates, however, this condition would most likely
cause regional water shortages and reductions in demand would
be required over a short-term.
The component technologies proposed for groundwater treatment
(i.e., air stripping and pretreatment using sodium
hexametaphosphate for scale control) are demonstrated and
commercially available. These technologies are expected to
be technically feasible and readily implementable.
Construction of new wells and a surface water treatment system
employ conventional methods that are demonstrated and readily
available.
The NPDEJs limits set for Ponderosa. are assumed to be applicable
for the other well treatment systems. Variations might be
possible for the unit at Bajura 3 since the discharge is
proposed to a point other than Honda Creek, and for the central
treatment system, since the effluent loadings are expected to
-------
-20-
be greater because of the higher flow. Actual effluent
limitations for any of the wells must be determined prior to
final design.
Cost estimates have been performed in detail for each of the
remedial alternatives. These estimates are summarized on
Table 11. Present worth costs have been estimated for a
range of operation and maintenance periods. These are 1, 5,
10, and 30 years.
This alternative does not address source control actions.
Insufficient site data on the source(s) is available to
identify and evaluate potential remedial alternatives for
source(s) remediation. However, the giroundwater plume has
been show to be decreasing in contamination .mass an average
concentration based on the'RI data' collected from September
1984 to January 1986. This may suggest that the source of
groundwater contamination has either been eliminated or has
decreased significantly from the period prior to September
1984. Additional investigative studies will be conducted to
fully define the source(s) of the groundwater contamination
and evaluate any potential of contaminants to migrate to the
groundwsrter -system at Vega Alta.
COMMUNITY RELATIONS
The Environmental Protection Agency has conducted numerous
community relation activities since the Vega Alta Public
Supply Wells Site was first listed as an NPL Site. The agency
has met with the citizens and local officials from Vega Alta
on numerous occasions. These meetings were intended to
describe the Superfund process and to inform the general
public of the progress of the Remedial Investigation. A
meeting was also held when the Feasibility Study and the
Preferred Remedial Action Plan was first presented to the
regulatory agencies. A public comment period starting on
August 7, 1987 was ultilized to solicit comments on the
Feasibility Study and the preferred remedy.
The public repositories for the RI and FS are the Vega Alta
Mayor's Office and the EPA Caribbean Field Office in San
Juan, Puerto Rico. The public was notified of the RI and FS
availability by a press release which appeared in the San
Juan Star and El Nuevo Dia. Following a request for extension
of the public comment period by the potentially responsible
parties (PRP's), the comment period was extended an additional
twenty-one days to September 21, 1987.
A summary of the comments raised concerning the FS and public
meeting are contained in the~attached responsiveness summary.
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-21-
ENFORCEMENT ANALYSIS
On August 29, 1983, EPA sent out 25 information request
letters to industries located within the PRIDCO industrial park
Information obtained in reponse to the requests revealed
industrial use of the same solvents that were detected in the
groundwater plume. On July 27, 1984 EPA notified three
companies of their liability to the federal government for
costs incurred in responding at the Site: General Electric
Company (as the parent of General Electric Controls, .Inc.,
and General Electric Pilot Devices, Inc.); Motorola, Inc.
(the parent of Motorola Radiomobile P. R., Inc.; and Harman
Automotive, Inc. (the parent of Harman Automotive P.R.,
Inc.). None of the Companies indicated a willingness to
voluntarily undertake the response actions outline in EPA's
Notice Letter.
Motorola has conducted a field investigation of their facility,
which EPA considers inconclusive.
On February 11, 1986 EPA sent information request letters to
Teledyne, and. West. Soil sampling results obtained during the
course of the RI from facilities owned and/or operated by
these two companies revealed that unusually high levels of
compounds had been released into the soils, which had not
appeared in the groundwater plume. Specifically, samples
from West showed trans-1,2-dichloroethylene at 58,000 ppb,
and xylene at 64,000 ppb. Samples from the Teledyne facility
showed 2-butanone at 17,000 ppb, and 2-hexanone at 8,900 ppb.
2-butanone appeared in the groundwater plume, but only at a
maximum concentration of 150 ppb.
After issuance of the present document, EPA will send special
notice letters to all of the PRP's in order to give them the
opportunity to implement the remedy selected'in the Record of
Decision. Simultaneously, EPA will invite the PRP's to
perform the second Operable Unit RI/FS, i .e., that portion of
the Remedial Action intended to investigate and remedy the
source(s) .
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-22-
Recommended Alternative
According to 40 CFR Section 300.68(i) of the NCP, the appropriate
extent of remedy shall be determined by the lead agency's
selection of a cost-effective remedial alternative that
effectively mitigates and minimizes threats to and provides
adequate protection of human health and the environment. In
addition, CERCLA, as amended by SARA, requires protection to
human health and the environment, which is cost-effective and
utilizes permanent solutions and alternative treatment technologies
or resource recovery options, and attains federal and^ state
ARARs to the greatest extent practicable.
After review and evaluation of the remedial alternatives
presented in the feasibility study, EPA presented Alternative
2 to the public as the preferred remedy for the Vega Alta
Public Supply Wells Site.
This alternative consisted of groundwater treatment at the
wellhead of four PRASA supply wells with discharge to the PRASA
distribution system. The wells proposed for treatment included
the following:
0 PRA*SA Pbnderosa (currently inactive)
0 PRASA GE 1 (currently inactive)
0 PRASA GE 2 (currently active)
0 PRASA Bajura (currently active)
Pretreatment with sodium hexametaphosphate (as a scale
inhibation) would be conducted. Dissolved volatile organics
would be removed via air stripping followed by polishing with
granular activated carbon adsorption. Treatment of the
groundwater from the four PRASA supply wells would be to the
equivalent -10:~6 ingestion risk level. This would satisfy
all Federal and State ARAR's related to drinking water.
Based on the input received from the appropriate Puerto Rico
regulatory agencies including the Department of Health (PRDOH)
the Aqueduct and Sewer Authority (PRASA) and the Water Pollution
Control Committee of Puerto Rico (WPCC) a modification to the
preferred remedial alternative resulted. In summary, their
input includes the following:
0 The Ponderosa well should be treated by air stripping with
effluent discharge to Honda Creek. An existing NPDES permit
for the Ponderosa Well discharge is available. .Ponderosa
well water should not be treated for drinking water use at this
point in time since the levels- of volatile organic compounds
are the highest in the site area and-the reliability of
operating and maintaining an effective treatment system may
be questionable.
^Tp^f^^'txec^'Tf'.^^
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-23-
The Ponderosa well discharge of approximately 400 GPM is not
needed to meet current drinking water demands for Vega Alta because
PRASA is supplying sufficient water frcm other sources to_
meet the estimated demand of 3.80 Million Gallons per Day (MGD).
This recommended alternative as revised involves treatment of
4 PRASA public water supply wells and hook-up of two private
groundwater wells to the PRASA distribution system. The
PRASA wells and private wells are:
0 PRASA Ponderosa (currently inactive)
0 PRASA GE 1 (currently inactive)
.° PRASA -GE 2 (currently active)
0 PRASA Bajura 3 (currently active)
0 Monterrey 2 (currently active)
0 G & M Cash and Carry (status undetermined)
Treatment of PRASA wells GE 1, GE 2, and Bajura 3 will be by
individual treatment systems consisting of scaling pretreatment,
air stripping and possibly activated carbon. The treatment
goal will be to reduce the risk level to the 1x10"^ magnitude
which will meet all federal and state ARARs. Treated effluent
will be discharged into the PRASA distribution system for
public use. The efficiency and applicability of the treatment
processes will be evaluated by bench-scale treatability tests
prior to final design and implementation of the specific
treatment systems. The bench-scale testing will also include
additional groundwater sampling to establish sizing and design
parameters. Sampling will continue throughout the implementa-
tion of this remedy. These tests will confirm the treatibility
of the groundwater using these treatment processess and will
determine specific design requirements.
Treatment of Ponderosa Well will be by scaling pretreatment
and air stripping. Discharge shall be to Honda Creek in
accordance with the existing NPDES permit; the effluent will
meet the same quality requirements as for PRASA wells GE 1,-GE 2,
and Bajura 3 such that Ponderosa treated water can eventually be
utilized for watersupply in the future. Activated carbon treatment
could be added to this treatment process should the need arise.
The Monterrey 2 and G & M wells will be shut down and each
user will be connected to the PRASA distribution system to
provide their water supply.
Individual well treatment systems (Alternative 2A) are expected
to provide greater operational flexibility than the central
treatment system (Alternative 2B) . Individual systems can be
shut down for routine maintenance with relatively minor effects
on the water supply compared to shut down of the central system
which has a flow rate of 1,450 gpm. Short-term shortages in
water supply from temporary shutdown .of the central treatment
system can be mitigated by in-line diversion of water from
adjacent regions of the PRASA distribution system. The
installation of parallel, backup units at the central treatment
system would prevent water supply shortages. However, capital
costs associated with a dual treatment system are considered
prohibitive for application of this treatment scenario.
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-24- •
The possibility exists for combining some of the treatment
plants. The air stripper/carbon units at GE 1 and GE 2 could
be combined in one treatment locastion because these two wells
are near each other and therefore can be easily combined.
As noted in the preface to the alternatives evaluation section
of this document, the alternatives were evaluated utilizing
nine criteria for selecting a remedy. Because of the basic
similarity between Alternative 2, 3 and the selected remedy,'
which is a variation of Alternative 2, this evaluation against
criteria is presented in aggregate form below:
1. Compliance with Applicable or Relevant and Appropriate
Requirements (ARAR's)
EPA must at least incorporate the following ARARs: Maximum
Contaminant Levels (MCLs)(established pursuant to the
Safe Drinking Water Act); Ambient Water Quality Criteria
(AWQC); Effluent Discharge Limitations (required under
the Clean Water Act); and Air Emissions (regulated under
the Clean Air Act). However, the FS evaluated remedies
which would exceed ARARs, and attain Maximum Contaminant
LeveJ. Goals (non-enforceable health goals established
purusant to the Safe Drinking Water Act), because the
Vega Alta population has been exposed to these hazardous
substances in their drinking water supply for several
years.
Clearly Alternative 1, the No Action Alternative would
not comply with ARAR's. The level of present and future
potential health risks would continue unabated.
Alternatives 2, 3, and the Selected Alternative will
attain-and exceed all ARAR's
Contaminant specific ARARs
- Maximum Contaminant Levels
Action specific ARAR's
- Ambient Water Quality Criteria •
- Effluent discharge limitations
- Air emissions
It should be noted that the ultimate attainment of MCLs will
require identification and control of source(s).
2. Reduction of Toxicity, Mobility or Volume
Clearly Alternative 1, the No Action Alternative will not
meet this criteria.
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-25-
Alternatives 2, 3, and the Selected Alternative will meet
this criteria to the extent that the system removes
contaminants from the groundwater, some reduction in
toxicity and volume is achieved. As the source(s) of the
contamination have not been fully investigated, the
degree to which the plume management and aquifer restoration
remedy reduces the volume of contaminants at the site,
cannot be determined at this time.
3. Short Term Effectiveness
Alternative 1, the No Action Alternative is not effective.
Alternatives 2, 3, and the Selected Alternative are
effective in the short term because in all cases, the
exposure of the population to the contaminants is eliminated
immediately upon implementation of remedy.
There are no short term risks associated with the implem-
entation of Alternatives 2, 3, and the Selected Alternative.
4. Long-Term Effectiveness and Permanence
Clearly, Alternative 1, the No Action Alternative is not
effective Alternatives 2, 3 and selected are all equally
effective in the long-term and will result in a permanent
remedy in that all contaminants will be removed, the
aquifer will eventually be restored and the public will
not be exposed to any risk from ingestion of contaminated
groundwater.
Long term effectiveness and reliability of the remedy
will depend upon:
1 - Operation and Maintenance
2 •- identification and Control of squrce(s) of
contamination
/
5. Implementability
Alternatives 2, 3, and the Selected Alternative are
easily implementable, do not depend on untested technology,
are reliable and equipment is easily available. However
Alternative 2 and the Selected Alternative are easier to
implement in that construction of a discharge line to
Honda Creek is not necessary.
6. Cost
Alternatives 2 and selected are the most cost-effectiveness
remedies for the site. Costs are again summarized below.
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-26-
Cost Summary
Alternatives-
1
2
3
selected .
Capital Cost ($1000)
.
4,106
6,502
3,677
Annual O&M
56
581
672
574
($1000)
7 & 8. Community and State Acceptance
The community and the Commonwealth of Puerto Rico were .
opposed to Alternative 1, the No Action Alternative.
The Community and State support the selected remedy in
general, incorporating control of the contaminant plume,
the pumping of wells and the utilization of treated water
in PRASA distribution system, except for the Ponderosa
Well,
The Community and the Commonwealth of Puerto Rico are
opposed to the utilization of treated Ponderosa well
waters in the distribution system.
EPA determined that this concern had recommended merit
and has been incorporated as a modification of Alternative
2 (the Selected Alternative); i.e., water from the
Ponderosa Well will be discharged directly into a surface
water body with the existing NPDES discharge permit.
9. Overall Protection of Human Health and the Environment
Alternative 1, No Action, would not meet this criteria as
contamination would remain in the groundwater system at
levels exceeding MCLs, posing contamination risks of
ingestion and exposure.
Alternative 2, 3 and the Selected Alternative would be
fully protective of human health and ensure that contamination
level would be reduced below MCLs, therefore this criteria
will be met.
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EPA WORK ASSIGNMENT NO. 143-2LA1
EPA CONTRACT NO. 68-01-7250
EBASCO SERVICES, INC.
RESPONSIVENESS SUMMARY
FOR THE
VEGA ALTA SITE
VEGA" ALTA, PUERTO RICO
SEPTEMBER 1987
NOTICE
The information in this document has been funded by the United
States Environmental Protection Agency (U.S. EPA) under REM III
Contract No. 68-01-7250 to Ebasco Services, Inc.
-------
VEGA ALTA SITE
VEGA ALTA, PUERTO RICO
RESPONSIVENESS SUMMARY
FOR THE
FEASIBILITY STUDY
AND
PROPOSED REMEDIAL ACTION PLAN
The U.S. Environmental Protection Agency (EPA) released the
Remedial Investigation on July 21, 1986 and the Feasibility Study
and Proposed Remedial Action Plan (PRAP) for the 'Vega Alta
site on August 10, 1987. Copies were placed on file at EPA's
office in Santurce, Puerto Rico and the Vega Alta Mayor4s Office
for a 30 day.public review and comment period from August 10,
1987 through September 10, 1987.
EPA also held a public meeting on August 19, 1987 at the Vega Alta
City Hall, to outline the remedial alternatives, present EPA's
preferred remedial alternative, and answer questions from
residents and local officials about the Vega Alta site.
A responsiveness summary is required by EPA policy for the purpose
of providing EPA and the public with a summary of citizen comments
and concerns about EPA's preferred alternative and EPA's responses
to those concerns. This community relations responsiveness
summary for the Vega Alta site is divided into the following
sections:
I. Overview. This section briefly outlines the proposed
remedial alternatives as presented in .the FS, including
the preferred alternative.
II. Background on Community Involvement and Concerns. This
section provides a brief history of community interest in
the Vega Alta site and a chronology of community relations
activities conducted by EPA during remedial activities.
III. Summary of Major Questions and Comments Received During the
Public Comment Period and EPA Responses to Comments. This
section summarizes major questions made verbally and in
writing to EPA during the public meeting and public comment
period, and provides EPA responses to these, comments.
IV. Remaining Concerns. This section discusses community
concerns that were not directly addressed during the
comment period and that EPA should consider in planning and
conducting the remedial design and remedial action for the
Vega Alta site.
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I. RESPONSIVENESS SUMMARY OVERVIEW
The Vega Alta site is located in the town of Vega Alta, Puerto
Rico. The site is an active public water supply well field, and
provides drinking water to approximately 28,425 residents in and
near the town" of Vega Alta, which is located approximately 32
kilometers west of San Juan.
Groundwater contamination was initially detected by USGS in June
1983 as a result of routine sampling of a public well.. Detected
contaminant's included volatile organic compounds (VOCs) such as
trichlorethene, 1,2-dichloroethene, and tetrachloroethene. As a
result of these findings, the Puerto Rico Department of Health
closed two wells in 1983 which resulted in a water shortage and
low system distribution pressure. The opening of a new well in
1983, however, has mitigated this situation.
Subsequent testing of additional public and private wells in the
area has also revealed the presence of contaminants. As a result
of these findings, EPA conducted a Remedial Investigation (RI) of
the Vega Alta site from April 1984 to March 1985 that included
soil sampling and the installation and monitoring of groundwater
wells, ^he objectives of the RI were to characterize the
groundwater, determine the nature and extent of contamination,
assess the contaminant source(s), and evaluate the migration
potential of contaminants from the ground surface to the water
table.
The FS for the Vega Alta site has been divided into two operable
units. The first operable unit specifically addresses groundwater
contamination. The source(s) of contamination will be addressed by
EPA as a separate operable unit in the future.
Groundwater was selected by EPA as the first 'operable unit for the
following reasons:
Management of contaminated groundwater is considered by EPA
to be the most important site objective to protect public
health and reduce public health risks associated with
ingestion of groundwater, and
Current site data is sufficient to evaluate the extent of
contaminant sources and to perform an FS of remedial
alternatives.
In identifying actions to remedy groundwater contamination, EPA
sought to:
Reduce contaminant levels in the groundwater,
Protect uncontaminated groundwater, and
Reduce contaminant levels at the tap to prevent
unacceptable human exposure.
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The report (September 1987) describes several remedial alternatives
that are briefly summarized below.
Alternative 1: No Action with Monitoring
Alternative 1 would not require the implementation of remedial
action and the level of present and future potential human health
risks would continue unabated. Groundwater monitoring would be
conducted to assess the level of public risk over time, and to
track migration of contaminated groundwater. Additionally,
sampling of tap water and groundwater would be conducted on a
quarterly basis.
Alternative 2; Groundwater Treatment with Discharge to the Public
Distribution System
Under Alternative 2, contaminated public wells would be treated by
air stripping and activated carbon adsorption to remove
contaminants to levels acceptable for human consumption. Four
public wells would require treatment: Bajura 3 (active), GE 1
(inactive), GE 2 (active) and Ponderosa (inactive). The migration
of contaminated groundwater would be minimized by continued
operation of the existing well field and the start up of two
inactive" wells. In addition, groundwater monitoring would be
performed to assess the performance of the remedial action. The
time period .for restoration of the groundwater to acceptable
quality is based on the migration rate of contaminants from the
sources) and the effectiveness of subsurface contaminant removal.
Alternative 3; Groundwater Treatment with Discharge to Surface
Water and Development of Alternate Water Supplies.
Alternative 3 involves the treating of contaminanted wells by air
stripping to remove contaminants to levels acceptable for the
discharge of groundwater into surface water. • The same four public
wells described in Alternative 2, would require treatment. Water
supply by new wells and surface water intake and treatment would
enable the public water supply system to operate without
shortages.
PREFERRED ALTERNATIVE
After careful evaluation of the remedial alternatives, EPA has
selected Alternative 2: Groundwater Treatment with Discharge to
the Public Distribution System, as the preferred remedial
alternative for the Vega Alta site. The components of this
alternative are:
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-3-
Treatment of groundwater at three wells (Bajura 3, GE I,
and GE 2) by air stripping and activated carbon adsorption;
Discharge of treated groundwater from the wells indicated
above back into the public distribution system for human
consumption and other uses;
. Treatment of groundwater at the Ponderosa well by air stripping
with discharge to surface water;
The Monterrey 2, and G&M wells will be shut down and each
user will be connected the the PRASA distribution system to
provide their water supply; and
. Monitoring of public and private wells and distribution
system taps to assess performance of the remedial action.
II. BACKGROUND ON COMMUNITY INVOLVEMENT AND CONCERNS
Community interest in the Vega Alta site is moderate. The
Community Relations Plan completed by EPA in June 1984 identified
four specific concerns, however, there is limited information
regarding the current status of these concerns. The concerns
described in the 1984 Community Relations Plan are as follows:
. Potential risk to human health associated with
trichloroethylene (TCE) contamination of potable water
supplies, and possible skin irritation resulting from
exposure to TCE.
"The potential for concern about water shortages in Vega
Alta in 1984, when several wells in the area were closed.
Concern existed regarding the possibility that the use of
wells could draw additional contaminants into the aquifer.
In 1984, the Puerto Rico Aqueduct and Sewer Authority
(PRASA) maintained the position that they were the licensed
authority to draw water from aquifers in Puerto Rico. It
was their opinion that they had responsibility for water
supply, but were not responsible for aquifer clean up.
This issue was identified in 1984 as a concern for local,
state, and federal officials.
During EPA's remedial site activities, several site-specific
community relations activities were conducted as part of EPA's
community relations program. These activities are briefly
summarized below.
In June 1984, EPA developed a site-specific community
relations plan for conducting community relations
activities at the Vega Alta site throughout the RI/FS.
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-4-
A fact sheet was developed and sent to community members
in August 1986. The purpose of this fact sheet was to pro-
vide interested residents with information on site back-
ground, nature of the contamination problem a't the Vega
Alta site, EPA's site investigation activites, EPA1 s goals
in investigating the site, and future EPA site activities.
A news" release was issued in August 1986 to inform
interested residents of an upcoming public meeting on the
RI for the Vega Alta site.
A public meeting was held on August 26, 1986 to discuss the
RI and the work plan for the Vega Alta, site.
A fact sheet was developed and distributed by EPA to local
. officials and community members in August 1987. The
purpose of this fact sheet was to discuss the FS, the
proposed remedial action plan (PRAP), and to present EPA's
preferred remedial alternative for cleanup of the Vega Alta
site.
On August 19, 1987 EPA conducted a public meeting to
discuss the proposed remedial action plan (PRAP), EPA's
preferred remedial alternative for cleanup of the Vega Alta
contamination problem, and to answer any questions pertaining
to the site. The meeting was attended by fourteen local
officials and seven interested residents from the Vega Alta
community. A summary of the comments raised at this meeting
is provided in Section III.
III. SUMMARY OF MAJOR QUESTIONS AND COMMENTS RECEIVED DURING THE
PUBLIC COMMENT PERIOD AND EPA's RESPONSE TO COMMENTS
A public comment period was held from August 10, 1987 through
September 10, 1987 to receive comments from the public on the
FS for Operable Unit 1 and EPA's preferred remedial alternative
for the Vega Alta site. The public meeing for the Vega Alta site
was conducted in two sessions on August 19, 1987 at 2:00 p.m. and
5:30 p.m. at the Vega Alta City Hall, Vega Alta, Puerto Rico. The
public meeting was conducted in two separate sessions in order to
accommodate community preference arid to ensure participation by
the maximum number of residents and local officials. The sessions
were attended by EPA officials, members of EPA's contractor staff
and local regulatory agencies officials to discuss the feasibility
study, and to apprise local residents of the agency's preferred
alternative for remediation of Operable Unit 1 for the Vega Alta
site. .~ Verbal comments received during the public comment are
categorized below by the following topics:
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. -5-
A. Technical Concerns Regarding Contaminants
B. PRP and Legal Issues
C. Communications Concerns
D. Health Risks
E. Other Concerns
In addition, to comments made at the public meeting, letters were
received from the following: the Office oftthe Governor, the i
Commonwealth of Puerto Rico Department of Health, the Puerto Rico
Industrial Development Company, the U.S. Department of the.
Interior, and the Commonwealth of Puerto Rico Department of
Agriculture. Comments made in these letters consist primarily of
recommendations on the remedial alternatives. The latter portion
of Section III of this responsiveness summary includes a brief
summary of these written comments and EPA's response to these
comments. In addition, copies of these letters are attached as
Appendix A.
VERBAL COMMENTS RECEIVED DURING THE PUBLIC MEETING
A. TECHNICAL CONCERNS REGARDING CONTAMINANTS
1. COMMENT: A local '"official inquired as to the source of
contaminants.
EPA RESPONSE: EPA stated that data indicates that the
source of contamination may be an industrial area in the
Municipality of Vega Alta. Since this data is
preliminary, EPA will conduct a more detailed second phase
study in order to determine the actual source and extent
of contamination.
2. COMMENT: A local official asked about the potential
effectiveness of the proposed remedial measures and who
would conduct groundwater sampling.
EPA RESPONSE: EPA explained that the project is currently
in the remedial design phase, however, pilot studies must
be conducted under laboratory conditions to verify the
efficiency of the proposed remedial measures before they
are implemented.
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3. COMMENT: A local official expressed, concern over the
potential time involved in cleanup activities, and
inquired as to who would conduct the cleanup.
EPA RESPONSE: EPA stated that the actual time involved is
difficult to determine. EPA has also identified PRP's
that will be asked or ordered to perform the groundwater
remediation.
4. COMMENT: A resident inquired about the 'cost of cleanup
and the time involved.
»
EPA RESPONSE: EPA stated that the cost of implementing
the preferred remedial alternative would be approximately
$4 million with $500,000 annual operation and maintenance
costs. EPA further explained that, at this point, it is
difficult to estimate the exact time peroid involved.
Upon completion of laboratory pilot studies, EPA will be
better equipped to estimate the time involved.
5. COMMENT: A resident expressed concern over the potential
effectiveness of remedial measures.
EPA RESPONSE: EPA explained that the effectiveness of
the preferred remedial alternative is very good. EPA may,
however, utilize additional pretreatment technologies to
ensure the effectiveness of the remedial measures.
6. COMMENT: A resident inquired about the potential for
obtaining non-contaminated water by drilling of new deeper
wells in areas that are not contaminated in order to avoid
the expense of cleanup remedies of potential non-
effectiveness of remedies.
EPA RESPONSE: EPA stated that drilling new and deeper
wells could present the risk of contaminating clean
groundwater. EPA policy requires remediation of
contamination rather than risking additional contamination
of clean water.
7. COMMENT: A resident inquired as to the time involved in
cleanup and who would assume jurisdiction over the long
term maintenance of the site.
EPA RESPONSE: Initially, EPA selects the remedial action,
. and affords the PRP's and opportunity to implement the
remedial measures. If the PRP's do not undertake this
project, EPA will assume responsibility for cleanup.
-------
8. COMMENT: A resident asked whether EPA could ensure that
contaminants are no longer released into the groundwater
after remedial actions are conducted.
EPA"RESPONSE: EPA stated that there are programs within
EPA that deal with preventive measures. Superfund,
however, addresses remedial action after contamination has
taken place.
9. COMMENT: A resident asked whether contaminants- found in
the water could be reduced through the use of home
distallation units.
EPA RESPONSE: EPA stated that these units are somewhat
effective, however, their efficiency depends on what
pollutants are being addressed, and the effectiveness of
the particular distillation device.
10. COMMENT: A resident asked whether systems will be used to
detect the potential failure of equipment used in remedial
action.
EPA RESPONSE: EPA explained that the equipment which will
be utilized has been previously tested and proven.
However, since the equipment is mechanical, the potential
for failure does exist. EPA will implement additional
monitoring systems in an effort to ensure the proper
operation of this equipment.
B. PRP AND LEGAL ISSUES
1. COMMENT: A local official asked about the legal
implications of EPA assuming financial and technical
responsibility for the supply and quality of drinking
water.
EPA RESPONSE: EPA responded that when a site is included
on the National Priorities List (NPL), EPAr through
Superfund, assumes the responsibility to conduct remedial
investigations and determine which method of cleanup will
be implemented. Legal negotiations regarding these
responsibilities must be coordinated with EPA, the U.S.
Department of Justice, and local government agencies. EPA
added that, if an activity such as the drilling of a well,
is conducted on a Superfund site, and that activity leads
to an increased pollution problem, the firm who drilled
the well, as well as the owner of the well, could become a
PRP under Superfund legislation.
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. -8-
2. COMMENT: A local official inquired about legal procedures
regarding identification and responsibility of a PRP.
EPA RESPONSE: EPA stated that Superfund legislation
provides for a PRP to assume responsibilities for cleanup
of a site. If they do not assume this responsibility,
Superfund monies are used for the cleanup and legal
pursuit of a PRP for recovery of expenses may be
instituted. These legal remedies, however, would not stop
any polluting activities. If Superfund monies are used in
Puerto Rico, the local government would be required to
contribute ten percent of cleanup costs. However, no
local legislation exists appropriating, these funds and a
question remains as to whether these fun'ds are available.
3. COMMENT: A local official asked who would be charged with
filing legal action against a PRP and what the proper
procedure for this action would be.
EPA RESPONSE: EPA responded that EPA would be
responsible. The procedure starts with the Environmental
Quality Board here in Puerto Rico. Following their
evaluation, they would then decide whether to proceed from
a local standpoint or transfer the case to EPA.
4. ^COMMENT: A resident inquired about the identification of
a PRP.
EPA RESPONSE: EPA stated that they have identified a PRP
and have notified the PRP that they are potentially
liable. EPA will be conducting negotiations with the PRP
in an effort to have the PRP assume responsibility for the
remedial studies and actions and to implement EPA's
preferred remedial alternative for cleanup of the site.
If the PRP will not assume this responsibility, EPA will
pursue this issue legally.
5. COMMENT: A resident asked whether there is any
legislation which compels a PRP to assume responsibility
for cleanup activities.
EPA RESPONSE: EPA stated that there is legislation that
provides for a PRP to assume these responsibilities,
however, the PRP must do so voluntarily. EPA added that
if a PRP does not assume these responsibilities, Superfund
monies are used for remediation and EPA then pursues the
PRP through legal channels.
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C. COMMUNICATIONS CONCERNS
COMMENT: A resident expressed'concern over the lack of
adequate comm-unication from EPA to elicit public
participation and the lack of information provided to the
public.
EPA RESPONSE: EPA responded that EPA encourages public
participation and input into Superfund remedial activities
an.d all information regarding the Vega Alta site is
available for public review. EPA intends to utilize other
types of communications media in order to reach the
maximum number .of residents in the most efficient manner.
D. HEALTH RISKS
COMMENT: A resident inquired about the human health risks
related to detected contaminants, and whether EPA has
conducted any studies addressing this in Vega Alta.
EPA RESPONSE: EPA stated that they conduct risk
^assessment studies in order to evaluate potential risk and
this information is available at the information
repositories to any interested party.
E. OTHER CONCERNS
COMMENT: A local official expressed concern about a
request from a commercial enterprise to increase
extraction of groundwater from the Vega Alta well field.
EPA RESPONSE: EPA stated that while Superfund is part of
EPA, it is not the division that grants such request.
EPA can inform the firm as to the legal implications of
their activities regarding use of an area that has been
designated a Superfund site.
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WRITTEN COMMENTS RECEIVED DURING THE COMMENT PERIOD
Several written comments were received during the public comment
period. These comments contained recommendations on remedial
alternatives, for this site. These comments and EPA's responses
are summarized below.
COMMENT: Following review of the proposed remedial action
plan, the Office of the Governor recommends the following
course of action:
»
1. Re-install the stripper at Ponderosa well, and
initiate its operation, discharging its waters to the
environment, monitoring its VOC "contents before and
after the stripper, in order to measure unit removal
efficiency and the level of contamination in the
aquifer. (This should be accomplished as part of
- Superfund activities in groundwater cleanup).
2. Install strippers at wells GE 1 and GE 2, to use
waters to supply the Vega Alta system, as needed.
3. Continue efforts directed towards obtaining artesian
well waters from the new Vega Baja and Ponderosa
sources.
4. Continue efforts for the installation of the Maguayo-5
piping system to provide dilution waters for the Vega
Alta system.
5. Design and construction of a holding/mixing tank
system to guarantee Vega Alta with a water supply
• having a maximum VOC concentration below 5 ug/1, as
per EPA requirements.
EPA RESPONSE: EPA appreciates the comments and has
considered them in selecting the remedial action to be
implemented. In particular:
1. The Recommended Alternative includes reinstalling the
stripper at the Ponderosa well. The effluent from this
stripper will be discharged to Honda Creek in compliance
with the NPDES permit. Sampling and analysis will be
.•'"! conducted to assure stripper performance and permit
'':] compliance.
1 2. Strippers will be installed at GE 1 and GE 2 and these
*3 waters will be discharged into the PRASA distribution
.:; system.
• $
; 3. The Recommended Alternative does not include the
provision of alternative water to replace Vega Alta
-,; contaminated water supply wells. The Recommended
; Alternative will instead provide water by treating
the contaminated wells which will also restore the
i" _ aquifer.
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4. The Maguayo-5 piping system is also considered
alternative water as Vega Baja and Ponderosa artesian
waters and is not part of the remedial action.
5. "The need for a holding/mixing tank system to guarantee
the quality of drinking water for the Vega Alta
community can be determined in Remedial Design.
COMMENT: Based on review of the draft FS for Operable
Unit 1 for the Vega Alta site, the Puerto Rico Industrial
Development Company offered the following recommendations:
1. The affected aquifer should be treated to eliminate
present or future pollution problems or reduce them as
completely as possible.
2. Only alternative 2 and 3 presented in the study appear
to be viable to treat the aquifer. The final decision
about the alternative to be implemented should depend
on the opinion of the regulatory agencies and PRASA.
'3. 'It may be reasonable to combine alternatives 2 and 3
to reduce the possible concentrations of organics in
the tap water. In such a case, part of the treated
water will be discharged to surface waters, especially
the water coming from the wells with greater concentration
of organics at a given time.
4. EPA and regulatory agencies should be very careful in
determing the responsible party(ies) of the original
discharges of solvents. It may not be advisable to
• point only to the present industries as the source of
the pollution.
/
EPA RESPONSE: EPA appreciates the comments and has
considered them in selecting the remedial action to be
implemented. In particular:
1. The remedial action will treat and restore the
contaminated aquifer.
2. EPA is selecting a combination of alternatives 2 and 3.
EPA has also considered the comments received from the
agencies as well as the Vega Alta community.
3. Again EPA is selecting a combination of alternatives 2
and 3.
4. EPA has very carefully investigated the potentially
responsible parties in the Vega Alta community and we
have considered past industrial activities.
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-12-
COMMENT: By letter dated September 14, 1987, Caribe
General Electric Products, Inc. (hereinafter, "GE.") raise'd
several concerns with the RI and the FS:
1. The use of "obsolete" data in the FS as well as a
lack of quantity assurance/quality control procedures.
In addition, the need to obtain additional data for
pretreatment processes, sizing of treatment units, data
on .alternative drinking water supply sourcesr
2. The evaluation of cost-effectiveness was not sufficient
in determining remedial actions;
3. Legal issues related to due process and EPA's notice
procedures under Superfund;
4. The fact that contaminant concentrations in the
aquifer have decreased over time;
5. GE proposed new remedial alternatives that would be
^limited to just supplying alternative water to Vega
^*Alta and increasing the pumping of uncontaminated wells
to provide the needed water.
EPA RESPONSE:
1. EPA used the data gathered in the RI to form the basis of
remedial activities evaluated in the FS. This is the usual
procedure with Superfund sites. EPA will gather current data
in the Remedial Design stage when the details on the actual
sizing of the treatment units will be determined. All of the
data gathered during the RI was quality assured/quality
controlled. EPA and EPA's contractors follow very specific
and strict procedures in these efforts and the quality assur-
ance/quality control documents are available through EPA if
necessary. Alternative water supplies were evaluated in the
FS in Section 3.2.5 Alternate Water Supplies on page 48. The
use of the Maguayo Well is a temporary measure only and the
continued use of other wells in the area would spread the
contamination in the aquifer. The use of new water supply
wells could spread the contamination as well. Surface water
sources identified include Rio Ciubuco and Rio de la Plata
and the Rio Ciubuco was preferred because it is a better
source as is described on page 53. Alternate water supply is
carried'forward as a remedial alternative in the FS to the
detailed evaluation stage. Ne"w water supply wells are des-
cribed on page 54.
2. EPA takes issues with GE on this topic. The Feasibility
Study was written using the CERCLA, as amended by SARA, the
National Contingency Plan, as well as all the current EPA
guidance documents pertaining to Feasibility Studies and
Superfund actions.
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. -13-
3. Contrary to GE's assertions, EPA did formally notify GE
of its intent to initiate investigatory actions itself, "and
did'attempt to bring GE into the RI/FS process as early as
possible, specifically, by way of letter on July 27, 1984.
GE did not volunteer to undertake response actions itself,
as EPA requested. EPA determined that GE was a potential
source of contamination in or around March of 1984, after EPA
TAT investigations revealed that GE operations and disposal
methods utilized the same chlorinated solvents that were
detected In the plume.
EPA did not defer source identification until after the selection
of the remedial action; as is stated above, EPA had already
identified sources. Rather, EPA defered issues of source
control until after selection of the remedial .action. As has
been stated upon numerous occasions, source control was considered
less critical from a public health standpoint since groundwater
remediation is estimateed to require a longer time period than
source control, which can be accomplished early in the lifetime
of the groundwater restoration period, especially in light of
the fact that decreasing concentration and mass of the plume
indicated that the plume had stabilized, i.e., the source of
contamination had either been eliminated or had decreased.
4. EPA agrees, and the RI and the FS so states, that the level
of contaminants in the aquifer have decreased over the course
of investigative activities. These concentrations have not
decreased to levels suitable for potable purposes, i.e., not
to the ARAR level necessary for purposes of this FS. Therefore,
remedial actions are necessary here.
5. The two new remedial alternatives proposed by GE are discussed
in the FS. However, the provision of alternate water, by itself,
would not remove contaminants from the aquifer. The removal of
contaminants is a necessary objective as stated in the FS.
COMMENT: By letter dated September 24, 1987, Teledyne
Packaging, Inc./ P.R., (hereinafter, "Teledyne") raised
several concerns with the RI and FS. Their concerns were
transmitted via letter from the law firm of Peter, Hamilton
& Scheetz. Teledyne's concerns are listed below:
1. Teledyne takes issue with not having sufficient time
to review the RI and FS stating that Teledyne was not
advised of its rights to comment on the FS'until September
5, 1987.
2. Teledyne states that the studies failed to consider
data trends that have shown contaminant level reductions
over time. Teledyne goes on to say that the data was
outdated, unreliable, and invalid. In addition, the
documents failed to assess health risks and appropiate
remedial alternatives.
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-14-
3. Teledyne also went on to say that the studies failed
to identify contaminant sources and failed to assess the
effectiveness of the treatment technology.
EPA RESPONSE:
1. The community at Vega Alta was informed of the results of the
Remedial Investigation on July 21, 1986 when EPA held public
meetings and presented and discussed the RI. Teledyne should
have been aware of this public outreach activity on the part of
EPA. In early August, EPA issued press releases announcing the
availability of the Vega Alta FS and also announcing the upcoming
public meeting to be held on August 19. The Vega Alta community,
which includes the industries in Vega Alta was therefore informed
of the availability of the FS.
On February 11, 1986, EPA sent Teledyne and information request
letter. Teledyne's soils and groundwater were sampled by EPA's
contractors in from September 1983 through March 1985. It is
therefore EPA's position that Teledyne had constructive notice of
government activity at the site.
2. EPA agrees that there have been reductions in contaminant
levels during the course of the RI. EPA used the data gathered
in the RI to form the basis of remedial activities evaluated in
the FS. This is the usual procedure with Superfund sites. EPA
will gather current data in the Remedial Design stage when the
details on the actual sizing of the treatment units will be
determined. All of the data gathered during the RI was quality
assured/quality controlled and is therefore valid data. EPA
evaluated health risks associated with consuming contaminated
water by establishing remedial objectives at the Maximum Contaminant
Level Goal. ;This level was established because the Vega Alta
population has already been exposed to these contaminants for
some time.
3. The RI identified the contaminant sources and Teledyne was named
as a contaminant source. EPA identified 2-butanone in soil at the
Teledyne facility. 2-butanone was identified in the groundwater
contaminant plume downgradient of the facility. This data, as was
the other data in the RI, was quality assured and therefore EPA is
confident that this data is valid.
The treatment technology of air stripping volatile organic compounds
is a proven and valid method of treating water to remove these
contaminants.
IV. REMAINING CONCERNS
This section describes additional community concerns that EPA
should be aware of in preparing to undertake the remedial design
and remedial action at the Vega Alta site.
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-15-
Comraunication of Information. Concern has been expressed that
information to the public regarding'the Vega Alta site has not
been adequate. Concern focuses on the relay of information to
community members regarding how the public is notified of public
meetings and the availability of remedial investigative findings,
Enforcement Actions. Local offices expressed an interest in
being keptinformed on the progress of any enforcement action
taken by the agency. -
Site Activity During the Remedial Action Phase. Future remedial
activities may.generate additional interest in the Vega Alta
site. The community should be informed as to the schedule,
type, and duration of these activities.
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FROM ICF METRO 9.17.1987 12:54 P. 14
APPENDIX A
WRITTEN COMMENTS SUBMITTED DURING
THE PUBLIC REVIEW
AND
COMMENT PERIOD FOR THE
VEGA AI/TA SITE
-------
FP.Of. ICF T1ETRO
, V
9. 17. 1987 12:55
P. 15
DEPARTAMENTO DE RECURSOS NATUR&ES
r:r. o i w
t*i
^ a 'fe
. Sr. Pedro Oelabert, Director
Oficina Regional para el Ceribe
x Agenda de Protecdon Aabiental Federal
R8: RBM III PROGRAM
DBAFT FEASIBILITY STO>Y
VBQA ALTA SUPHRFUND S ?
Batlsado tenor Gelabert:
Heioa evaluado el documento do referenda jr le •omei->»i.^ u
continuaci6n nuestros eoaentarioa para ait eoaaideraci6n y -..-ci6n
pertioeote.
El JDepartamcntb de' Reeuraoa Naturalet eati da aeuerao coo la
Agenda da Protecciin Aabiental (APA) en au enfoque de • •• poner,
eono privera acciin, el atander la aituociftn da cobtavin- .;x«n dal
acuifero en Vega Alta, orieotando eata hacia el prpbleaa da riea-
joa a la aalud, eaociadoa a la utilizaci6n del afua r.>h*-»rranea
COBO fuente da agua potable y a atendar al problena d« ••ontaaioa-
Ci6n del acuifero. Sin eabargo, la aoluci6o final dei t>robl«»a
raquorira qua ae identifiqua adacuadaaente y a la brevedttd posi-
bla la fuente de contaainacion y la foraa en qua data llaKn haata
el aguo aubterranaa. Laa alternativaa qua APA ha conoid- -do a
corto plaxo augieren qua la aoluci6o del probleaa pued- oiar
haata trelnta (30) afioa. Bate Departaneoto eapara una ao • «i4n
per*anente al probleaa planteado an un plaso de tievpo raxon* ll§-
•ente corto, dad* la iaportancia vital dal acuifero para »a- f-
facer laa nacaaidadaa da abaato preaentea y futuraa dal pueb" • 'da
Vega Alta.
la evideote que urge el qua •• paaa» ittaediataaentet a
•egunda etapa de diagniatico dal probleaa; ea decir, a la idem
ficadon da la fuente da cootaxiaacion y a loa »ecanis»oa ?•
•OTiaiento dal contawinaota hacia la fuente de agua.
Teneaoa una opinion difarente a APA, an cuaato a laa aedidaa
eapecifieaa recoaendadaa a corto plaao. Rate Oeparta»ento y
otraa agenciaa gubernananlalea qua coapoaea al Coaite Para al
Control da la Contaainaclin del Agua (en al cual APA eata
repreaaatada), nan evaluado el problema de Vega Alta de foraa
integral, to*ando an conalderaci6n laa poaibilidadea de la AAA,
que ea la agenda gubernaaental vaa afectada por el probleaa de
«)v*f.
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FROM ICF HETRO 9.17.1987 12:56 P. 16
I >
- SET, 0 2 1987
p&gina 2
Contaainnci6n en o»to CBBO. Se ha sugerido un poaible cur»o do
accion para reaolver el probleaa de Vega Alta a corto plato.
Batas recoBendeciones del Coaite eatan contenidaa en una carta
del 17 de agoato de 1987 qua le aoae'tiera a BPA la. Junta de Ca-
lidad Aabieatal (JCA) relaciooada eon aate aaunto. Bl Departa-
•onto, coao parta da este Coaite, subscribe la opini6o da la JCA
expreaada en esta ceaunieaci6n. Sa iocluye copia de e«ta carta.
En tarainoa eapeclfieoa, quereaoa aeflalar aobre eate docu-
•ento, qua hay incertidumbre »obra la eaotidad axaeta do agua qua
loa pozoa da la AAA an el area contaainada auplian a Vega Alta.
Sa ha iodicado qua eata eifra puada aer da alredador da 3 atfd
vQlaaeDte. Esto puede iaplicar qua. al pcrlodo de boaboo nece-
aario para, al procaao da la llvpieca d«l aculfaro puede aer
ttayor. APA deba preciiar esta infor«act6a « incorporarla a lea
•edidaa. La diferencia reaulta del hecho de que en el inventario
de loa poeoa qua con»ider6 la APA (tabla 1.1. pig, 7) «e inclu-
yeron varioa Cooaervaci6n y Adainia-
tracion da Las Aguaa de -Puerto Rico, eopia del cual aa inoluye.
Confieaoa aaatener coao haata el presente la a la-— eatrecha
colaboraci6n entre aabaa agenelaa para aaegurar una eflciente
iaplantaci&o da nueatraa roaponaabilidadea.
Anejos
uato A. MeadeB,
Secretarlo
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rKuniCFHETRO' * ' V.17.19««'12.I5? P. 17
COMMONWEALTH OP PUERTO RICO / OFFICE. OF THE GOVERNOR
_' SnvlrcxYrtentaJ
Oualfty Board
August 17, 1987
Mr. Pedro A. Galabert, Director
Caribbean Field Qffict
US Environmental Protection Agency
1413 Fernandez Juncos Ave.
Santurce, Puerto Rico 00909
.Dear Mr. Gelabert;
•
Pertaining to the "Draft Feasibility Study Report", which your
office recently submitted to this Board for comments, we wish to
indicate activities which have been carried out and are not included
in aaid report. These were personally communicated to Mr. Jose1
Font, by Mr. C.M. «Jia4n«z, during a. meeting on this subject held at
your facilities on August 6, 1987.
The Vega Alta situation, as well as similar other situations in the.
island, where aquifer contamination has been detected, has come to
the attention of this Board and become a priority item. To this
effect, in September of 1986, and under the coordination of this
Agency, the Committee for the Control of Water Contamination wa»
created) having as Members representatives from the Department of
Health, Department of Natural Resources, the U.S. Geological Survey,
Aqueduct and Sewer Authority, and the U.S. Environmental Protection
Agency. Ms Racqueline Shelton is your representative, in this
Coeaittee. '
While the stated purpose of the Coaunittee is to explore and
recommend alternatives for water decontamination, the search for
adequate sources of drinking water 'became • natural task,
particularly In locations such as Vega Alta, where the aore
stringent scheduled standards could create a lack of water for the
region. AJ a result of our activities, various alternatives have
been explored and actions hare been initiated which have a direct
bearing la the schemes presented as options in your Report.
A brief sumaary of these is as follows;
Sep. 30, 1986 *) The AAA and Oept. of Health agree that it
is easier and more desirable to purchase
and locate new strippers on wells Gfi-1 and
QE-2 than to move the Ponderosa stripper to
such sites.
b) The utilization of Ponderosa water for
public consumption would require trials
with dual strippers in series to determine
c*ncfi Of "HE BOMO to* Ott. PLAQUE tr count* & PO*»«AOA *wtxi «d6*«s. r o »ox i u«
«: JUfl
;*-rf™v7^^
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FROM ICF METRO
9.17.1987 12:37
PTlS
Oct. 28* 1986
Nov. 25, 1986
Jan 22, 1987
Feb. 24, 1987
if required levels can be attained, plus
0 fc M program to * guarantee sta
efficiency.. This alternative was not
considered practical.
c) Surface water sources in Manati will be
employed in Vega Alta) but this is a long
term project of no value for the present
situation.
a) Utilization of strippers in series with
activated carbon filter's at wells QE-1 and
GE-2 was evaluated at $255,000, and more
than a year for design and construction.
b) Bringing water from Maguayo-5 and improving
the distribution net for remaining Maguayo
wells was evaluated at $1,556,000. This
alternative was selected for design and
construction. This source will enable
substitution for contaminated sources at
Vega Alta. Tanks for mixing and dilution
would be required in order to bring down
contamination levels in the Vega Alta water
fraction to be used.
e) Surface water from Rio Indio remains a
option. This would require a traatmur
plant and systems for dilution with
existing Vega Alta sources.
a) The AAA informs that existing water supply
systems can provide up to 3.85 MGD, while
demand projections for 1995 are of 4.07
MOO, for Vega Alta.
t
a) the Maguayo to Vega Alta supply scheme i$
expected to be operational by mid 1987.
Water delivery expected is 800 gp». The
equalization tanfc will be built as r secoag
stage of the project.
a) A spring located in the Maguayo area was
evaluated to yield between 200,COO to 1
MGD. A small fraction of its waters are
presently used to supply a livestock farmt
the rest flows freely to a receiving water
body and eventual discharge to the sea.
This source will remain as a possible
alternative for future consideration.
^
b) The alternative of strippers in series at
Ponderosa was considered as unnecessary
-------
possible water supply, since other source*
are now possible at lower cost.
e) Garrochaies 1 & 2 were reported cloaed due
to CC/4 contamination. Sampling! are to b«
conducted to determine if and when they car.
be placed in service.
Jun. 31 / 87 a) Based upon, a listing of the operational
status of well*, provided By the AAA, a
priority list tot remedial action* was
prepared -by EQB. Top priority is assigned
to operational wella, yielding higher
valueso2VOC contamination, down to a
level of 5 mg/1, (See attached list*)
July 23, 1987 a) The Maguayo-S well water supply alternative
is expected to start operations by October,
1987* Artesian sources, mixed with
Maguayo-5 and treated General Electric - 1
and 2 can provide the necessary water
supply for Vega Alta.
b) The Artesian well located at Vega Baja was
completed. This well could provide froa
^ . 300 to 600 gpm to the Vega Alta system.
c) The Garrochales-3 well does not exhibit VOC
contamination, for which it will remain
operational.
i
Noter •Information obtained early in August from AAA
indicates that an Artesian well was completed at the
Pondero«a wall site. Bo information is yet available
oa it» y«14.
Conclusion!
/
After reviewing the 8PA Remedial Action Plan for Vaga Alta, and
taking into consideration the progress so far made by the water
Quality Control Committee, we recoa»eaded the following course of
action/
1. Ra-inatall the stripper at Ponderosa well, and initiate its
operation* discharging its waters to the environment,
monitoring it* voC contents befora and after the stripper, in
order /to measure unit removal eficiancy and the level of
contamination in the- aquifer, (This should be accomplished as
part pf superfund activities in groundwattr cleanup.)
i
2. Install strippers at wells GB-i and GC-2, to usa waters to
supply the Vega Alta system, as needed.
-------
FROH 1CF HFTPO . 9.17.1987 12:39
3, Continue efforts directed towards obtaining Artesian well
water's from the new Vega Baja "and Ponderosa sources.
4. Continue efforts the installation at the Maguayo-5 pipir.c
system to provide dilution waters for the Vega Alt* system.
5. Design and construction a holding/mixing tank system to
guarantee Vega Alta with a water supply having a isaxinum voc
concentration bftlow 5 ug/1, as per coming EPA requirements.
We hope these recommendations are useful to responds towards EPA
goals. Please feel free to request additional^ clarifications, if
needed
Co
Sarytoa Rohana, Jr.
Chairman
CMJB/iv
ce: Sr. Tomds Rivera
Sxta,. Mariaol Morales
Miembros Comitd de Agua
-------
ICF METRO 9.17.1987 12:39 p.2i
COMMONW6AIYM OP PU««TO BICO J {-
DEPARTMENT OF HEALTH i ,;:; ( ..
OFFICE OF THE SECRETARY
fiST W M PH. 5- 05
Mr. Pedro Ceia«bert, Director
Caribbean Field Office
U.S. Environmental Proceeded Agency
1413 Fernandas Juneoe, Ava.
Santurce, Puerto Rico 00909
Dear mister Gelabert t
In relation Co the " DRAFT FEASIBILITY STUDY REPORT " we
have, the following coaaents i
1. On May 5, 1983 the Department of Health (DOH) ordered the
closing of Ponderosa well and air stripper treatment for
Gtt-1 and Ce-ll well* located nearby, PRASA installed the
«ir etripper at the Ponderoea well instead.
"t. Oh April 1985 the DOR ordered PRASA to t
a. Open Ponderota well and- pump treated veil
water from air etripper to the approved
receiving water body and comply with the
monitoring specified requirements and
effluent limitations in the NPDRS permit
given to PRASA by the USEPA on Auguet 24»
1984.
b. Monitor for concentrationa &t T3 and T4 of
valla CE-l, GB-11 and Ponde.rosa on a weekly
basia*
The purpote of theae requested actione were :
* To iaprove the quality of the water pumped
froa GB-11..
* To lower concentrations of contaminant*
on CE-l well which reaaine closed with
a possibility in the near future to open
tha v
-------
FROM ICF METRO 9.17.1987 13188 p.22
* To clean the «aulf«r bv extracting water from
the Ponderot* well which cone tin very high
concentration* of the contaminants.
* To provide the needed dace Co evaluate
Che effectiveness of the air etrlooer in
the removal of T3 and TA.
3. The DOH have two representatives members In the
Committee for the Control of Water Contamination
which It under the coordination of the Environ-
mental Ouaiitv Board. This committed has been
studying and evaluating the situation in Veaa
Alta. At a result it WA« recommended * couree of
action In a letter tent to you on AuKuet 17.
1987 which toe »uDDorC«
4. Finollv. we ere enclosed a coev of Regulation 4 SO.
"* Articles IZI and IV of thlt Regulation should be
consider in the Regulatory Referenced (Appendix 0).
Yours truly
cardJ.D
Attifltant Secretary for
Environmental Health
-------
FROM ICF METRO 9.17.1987 13«81 P.23
COMMONWCALTK or pjtftro mco
. PUBRTO RICO INDUSTRIAL DEVELOPMENT
L. I4NACIO tt»
*m ^_ ..J.A..IAA • •"s" '—••—-•—•> *~vhn ;>* "iwO Qvvltt
, ACMCML «V4A«»» T
-------
FROM ICF METRO
9.17.1987 13:81
P. 24
OF
fltco INDUSTRIAL H«VKI.OPM*MT COMPANY
August 24, 1987
Eng. Jose font
Draft Feasibility Study
Page 2
4. It is our opinion that EPA and regulatory agencies should be
very carefull in determining the responsible party(ies) of the
original discharges of solvents, ft may not be advisable to point
only to the present industries as the source of the pollution.
Thank you
matter.
for your Interest in consulting our agency about this
Rafael
President
Puerto Rio
neral Manager
strial Development Company
-------
FROM ICF MPTRO
COMMONWEALTH Of PUCMTO
CRICULIURE
101M
Pi«ld Offict
1413 Fernandez Juncx>« Avenue
Sancurct/ Puerto Rlcb 00909
Me.
9.17.1987 13:02
P. 23
fte^
^J?
September 4, 1987
ew
5 3
Rtl
Puerto Rico
7, 1987,
, let u» Xnow if we can be of any further wsiatance.
Cordially your a,
Secretary of Agriculture
tUIMI AND DEDICATE u THE SERVICE OF AORJCVWUW 3..
sj?'.'^v"iiv3SJrv:'",v';\'7r;y:r'-. .^yr^-vrv
-------
,r«un itV HETRO ?. 17. 1987 13:03 J.jt'
United States Department of the Interior ^
FISH AND WILDLIFE SERVICE "TC*
CARIBBEAN FIELD OFFICE *** *
P.O. 80X491
•OQUERON, PUERTO MCO 00«22 /•» £y,
September 5, 1987
O'
?
Mr. Pedro A. Gelabert ^p £>>
Olrector, Environmental Potectlon Agency 2~ 3 S"
Caribbean Field Office oo w w=
1413 Fernandez Juncos Avenue S- ^ :
Santurce, Puerto R1co 00909 of^ <*> ''•
Re: Draft Feasibility Study,
Vega Alt* site
Dear Mr. Gelabert:
This 1s In reply to your August 7, 1987, letter requesting our
comments on the above referenced document. We find the document to be
well-written end Informative. Since the problem at Vega Alta deals
exclusively with groundwater conatam1nat1onf we do not anticipate
significant Impacts on federally listed threatened or endangered
species, or their critical habitats. We therefore agree with your
recommended clean.up action and urge you to continue monitoring until
the contamination problem 1s resolved.
Sincerely,
Robert T. Pace
Acting Field Supervisor
cc:
ONR, $an Juan
EPA, New York
EQB, Terrestrial Ecology Division
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