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

-------
                                   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
18. DISTRIBUTION STATEMENT
19. SECURITY. CLASS iTIlis Rtporti
       None
21. NO. OF PAGES
     52
                                               20. SECURITY CLASS iTtlit pagtl
                                                       None	
                                                                          22. PRICE
SPA Pen* 2220-1 (R«». 4-77)    Previous COITION i* OSSOUCTK

-------
                                                     INSTRUCTIONS

1.   REPORT NUMBER
     Insert the LPA report number u it appears oh the cover of the publication.

2.   LEAVE BLANK

X   RECIPIENTS ACCESSION NUMBER
     Reserved for use by each report recipient.

4.   TITLE AND SUBTITLE
     Title should indicate  clearly and briefly the subject coverage of the report, and be displayed prominently. Set Mihiule. if ux-U. in tmalicr
     type or otherwise subordinate it to main title. When a report is prepared in more (tun one volume, repeat Hie primary title. add volume
     number and include subtitle for the specific title.

3.   REPORT DATE
     Each report shall carry a date indicating at least month and year. Indicate the
     appro**!, datt of preparation, tie.).
                                                                               on which u «.i> ^levied /e.g.. Jan- rpani-
       zation.

   t.   PERFORMING ORGANIZATION REPORT NUMBER
       Insert if performing organization wishes to assign trm number.

   9.   PERFORMING ORGANIZATION NAME ANO ADDRESS
       Give name, street, city, slate, and ZIP code. List no more than two levels of an organi/ational Itirearcliy .

   10.  PROGRAM ELEMENT NUMBER
       Use the program element number under which the report wa.s prepared. Subordinate numbers may be included in purenthcx-s.

   11.  CONTRACTYGRANT NUMBER
       Insert contraCTor granf number under which report was prepared.

   12.  SPONSORING AGENCY NAME ANO ADDRESS
       Include ZIP code.

   IX  TYPE OF REPORT ANO PERIOD COVERED
       Indicate interim final, etc.. and if applicable, dales covered.

   14.  SPONSORING AGkNCY CODE
       Insert appropriate code.

   19.  SUPPLEMENTARY NOTES
       Enter information not included elsewhere but useful, such ax: Prepared in cooperation with, translation »i. I'rcx-nicd jt cunivrrmc »i.
       To be published in. Supersedes. Supplements, etc.

   16.  ABSTRACT
       Include a brief 1200 words or Itnl factual summary of the most significant information contained in iliv report. II ilu- rcpwi touiains a
       significant bibliography or literature survey, mention it here.

   17.  KEY WORDS ANO DOCUMENT ANALYSIS
       (a) DESCRIPTORS -  Select from the Thesaurus of Engineering and Scientific Terms the proper auilmri/cd terms that identify the major
       concept of the research and are sufficiently specific and precise to be used as index entries fur caialotiint:.

       (b) IDENTIFIERS AND OPEN-ENDED TERMS • Use identifiers for project namo. code names, equipment designators. etc. U-c open-
       ended terms written in descriptor form for those subjects for which no descriptor exists.

       (c)COSATl I IELD GROUP -I- ield and group assignments are to be  taken from the mSCOSAM Suhiect Catepiry List.  Since the ma-
       jority of documents are multidisciplinary in nature, the Primary field/Group auignmentls) will be six-niic dixiplmc. urea of liunun
       endeavor, or type of physical object. The application! s) will be crou-rcfcrenccd with secondary I icld/< iritup j>M|;nineiiis ihut will follim
       the primary postingls).
18.  DISTRIBUTION STATEMENT
    Denote reusability to the public or limitation for reasons other than security for example "
    the public, wtth-address and price.

19.420. SECURITY CLASSIFICATION
    DO NOT submit classified reports to the National Technical Information service.

21.  NUMBER OF PAGES
    Insert the total number of pages, including this one and unnumbered pages, but exclude distribution list, il any.

22.  PRICE
    Insert the price set by the National Technical Information Service or the Government Priming Office, if known.
                                                                                             l.'nli ..... cd." < iic jny jv.ul.ilnliiy in
EPA P*rm 2220-1 (R... 4-77) (R«»«r.«)
 plvv2--c:~'^?^"r'-'^

-------
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.

-------
                    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

-------
                             -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

-------
          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.


-------
                                                    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

-------
         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

-------
                                             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

-------
                             -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

-------
                             -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"-^"^^

-------
                                                                                                                                                             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

-------
                              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

-------
                             -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.

-------
                              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.

-------
                             -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.

-------
                             -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
ALTERNATIVE
tA.tA
t».3B
TREATMENT
SYSTEM
PONOEftOSA
•£1
•et
•AVUNA s
CENTRAL
(* SWELLS)
•AJUMA S
rtOWMATC
•>•»
•00
000
ISO
•00
I49O
•00
1
)

c
0
OUESTNANT
M> v fmtmtm
pi
0

1
/~-%m
                              ruow
                                        IM-LINC
                                       1TATK MIKCT
                      •CLLHEAD ,
                        PUMP   {
                              I
                                                                  ,   mSCMAftOE
                                                                  (ALTERHATIVt NC 9)
                            LEAD/LAO
                              PUMPS
v~T"twu>T
   I  «AC UNITS
                                                                                  POLIIHINO
                                                                               1ALTDINATIVC Na 1}
                                             •HOIK* PANALLtL «AC UNIT! WIU. M PHOVIDEO
                                                   FOM ALTCNNATIVC* !• • *•.
              •  TO
            OltTMIH/TION
              SYSTEM
            (VUSUROE'WM
              ft
           GRQUNDWATER TREATMENT PROCESS FLOW DIAGRAM
                            (ALTERNATIVES 2 ft 3)
                      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

-------
                              -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.

-------
                             -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.

-------
                             -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) .

-------
                             -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'.^^

-------
                             -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.

-------
                             -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.

-------
                             -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.

-------
                                -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.

-------
              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.

-------
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.

-------
                               -2-

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:

-------
                               -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.

-------
                               -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:

-------
                             .  -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.

-------
                           -6-

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.

-------
                        .   -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.

-------
                               -9-

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.

-------
                                         -10-

          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.

-------
                        -11-
 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.

-------
                             -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.

-------
                          .  -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.


-------
                             -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.

-------
                            -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.

-------
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.


-------
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

-------
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^^

-------
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

-------