United Stales
Environmental Protection
Agency
Office of
Emergency and
Remedial Response
EPA/ROO/R02-86/03S
S*ptemberl98a
&EPA
Superfund
Record of Decision:
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TECHNICAL REPORT DATA
(PittU/! 'tad '"SlI'UCtlO"S 011 tht ,tvt'!t btfon co,""lttinIJ
,. 1II."OIilT NO. 12. 3. RECIPIENT'S ACCESSION NO.
EPA/ROD/R02-86/036
.. TITL.E AND SUITITL.. 5. RE"OFIT DATE
SUPERFUND RECORD OF DECISION c....",..~_h~~ In 1 QQ/:
Brewster Well Field, NY 8. PERFORMINO OROAN'ZATION CODE
7. IIIUTMOIII.S) 8. PEFIFORMINO OROANIZATION REPORT NO
t. PERFORMING OIilGANIZATION NAME IIINO AOORESS 10. PROGRAM EI..EMENT NO.
11. CONTRACT/G"ANT NO
12. SPONSORING AGENCY NAME AND AOORESS 13. TYPE OF REPORT AND PERIOO COvEI'IEO
U.S. Environmental Protection Agency 1:';...",1 ~I"IT"I ,,~~~.
401 M Street, S.W. 1.. SPONSORINO AOENCY COOE
washington, D.C. 20460 800/00
15. SU""L.EMENTAFlY NOTES
18. A8STRACT
The Brewster Well Field, located on the northern bank of the East Branch Croton
River, is three-quarters of a mile east of the Village of Brewster, Town of Southeast,
Putnam County, NY. The land to the north and west, containing the community of Brewster
Hill and the Vi llage of Brewster respectively, is largely residential, while most of t h~
land south of the site area is occupied by commercial or 1 ight industrial facilities.
Since 1954 when Well ~ield No. 1 was developed, the Village of Brewster has used the
aquifers beneath the Village-owned land as a water supply source. In 1967 Well Field
No. 2 was brought on line. The t'NO well fields consist of a total of 18 shallow 'Ne 11 s.
In 1978 evidence of volatile halogenated organic compound contamination from an
unidentified source first appeared. Five alternative water sources were subsequently
added to the water supply system. Prior to drought conditions arising in 1981, Sast
Branch Croton River surface water was also used at times to supplement the water s u p'o 1 Y
system. Since 1979, the Village of Brewster has conducted studies to identify potentia
alternative ground water sources and to test spray aeration as a potential treatment
method for VHO removal. In 1984 under a Cooperative Agreement with the EPA Office of
Research and Development, the Vi llage installed a fullscale packed column for treatmen:
of the entire village supply. It has been concluded that treatment of existing sources
is the most promising of the alternatives for solving existing contamination
(See attached sheet)
17. ",EY WOPIOS AND OOCUMENT ANAI..YSIS
a. OISC..."TOFlS b.IOENTIFIERSiOPEN ENOEO TERMS ,. caSA T I F ,cld. G ,Ou ~
Superfund Record of Decision
Brewster Well Field, NY
Contaminated Media: gw, sw, soil
Key contaminants: VOCs, TCE, PCE, DCE
1.. 0lSTRI8uTION STATEMENT 19. SECURI TY CI..ASS , Tills Rl!ponl 21. NO. OF PAOES
None "i"i
20. SECU I'll TY CL.ASS i Tills pa,,, 22. PPlICE
,,~-~
(,
!'A '0'''' 2220-1 (It... 4-77)
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EPA/ROD/R02-86/036
Brewster Well Field, NY
16.
ABSTRACT (continued)
problems, and based on trends, it is believed that the Well Field has
reached a steady state condition, whereby contaminant levels are not
expected to increase at the Well Field in the future. VHOs have been the
primary contaminants detected in the ground water. The principle
contaminants were found to be tetrachloroethylene, trichloroethylene, and
1,2-dichloroethylene.
The selected remedial action includes: continued operation of the
existing air stripper to treat the water supply; design and construction of
a ground water management system which will include ground water extraction
wells, air stripper treatment of extracted ground water and reinjection of
treated water. Details of the ground water management system will be
determined during design. The estimated capital cost for this remedial
action is $163,912 with annual O&M of $27,468.
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RECORD OF DECISION
REMEDIAL ALTERNATIVE SELECTION
SITE
Brewster Well Field, Brewster, Putnam County, New York.
DOCUMENTS REVIEWED
I am basing my decision primarily on the following documents
describing the analysis of cost effectiveness of remedial
alternatives for this Site:
- Brewster \Jell Field Focused Feasibility Study
- Brewster Well Field Remedial Investigation
- Brewster Well Field Feasibility Study
- Staff Summaries and Recom~endations
- Responsiveness Summary
DESCRIPTION OF SELECTED REMEDY
This Record of Decision calls for the following actions:
o Continued operation of the existing on-Site packed column
air stripping system at the Well Field to provide to the
Village a water supply that exceeds applicable or relevant
and appropriate standards, thereby providing a very high
level of public health protection: and
o Design and construction of a groundwater management system,
consisting of extraction wells, treatment of the extracted
water by an additional off-Site air stripper, and reinjection
. of the treated water, to contain the plume of contamination
and restore groundwater quality south of the East Branch
Croton River.
DECLARATIONS
~
Consistent with the Comprehensive Environmental Response, Com-
pensation, and Liability Act of 1980 (CERCLA) and the National
Contingency Plan (40 CFR Part 300), I have determined that the
continued operation of the existing air stripping system treating
the Village of Brewster's water supply and construction of a
groundwater management system to contain the plume of contamina-
tion and restore groundwater quality south of the River, is' a
cost-effective remedy and provides adequate protection of
public health, welfare and the environment. Furthermore, I
have determined that it is necessary to undertake a supplemental
Remedial Investigation and Feasibility Study to gather additional
data and to evaluate the necessity to implement source control
measures. A determination regarding future source control
actions will be made upon completion of this work.
The State of New York has been consulted and agrees with the
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operation, maintenance, and monitoring activities to ensure the
continued effectiveness of the remedy. These activities at the
proposed off-Site air stripper are presently considered eligible
for Trust Fund monies for a period of one year, although pending
CERCLA legislation may affect this eligibility and/or the period of
eligibility. However, EPA will not participate in the cost of
these activities at the existing on-Site air stripper. Said costs
will continue to be paid by the Village of Brewster.
Funding of this remedial action will occur at .the time of CERCLA
reauthorization: moreover, I have determined that the action being
taken will be appropriate when balanced against the future availability
of Trust Fund monies for use at other activities.
SV~~"IM.<. k,I1S",
,
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SUMMARY OF
REMEDIAL ALTERNATIVE SELECTION
BREHSTER WELL FIELD
SITE LOCATION AND DESCRIPTION
The Brewster Hell Field is located on the northern bank of the
East Branch Croton River, 3/4 of a mile east of the Village of
Brewster, Town of southeast in Putnam County, New York. The
Site is approximately 3 miles west of the Connecticut/New
York border and approximately 47 miles north of New York
City. Interstate 84 passes just to the west of the Site (see
Figure 1).
The land to the north of the study area, containing the
community of Brewster Hill, is largely residential with some
agricultural use. Most of the land south of the study area
is occupied by commercial or light industrial facilities. To
the west is the residential community of the Village of
Brewster.
The 1980 Census records the population of Putnam County as
77,193. Projected 1980 figures for the Town of Southeast and
the Village of Brewster are 15,500 and 1,700 respectively.
The municipal water system serves the Village and several
areas in the Town of southeast, a number of business establish-
ments and the Consolidated Rail Corporation's Putnam Junction
Rail Yard. Residential users alone count for an estimated
2,100 people.
. Additional potential receptors are downstreaM users of the
East Branch Croton River which contributes to the Croton
Falls Reservoir approximately 3.5 miles downstream. The East
Branch Croton River flows adjacent to and south of the Well
Field. Three thousand feet to the east of the Site (upstream)
the River is impounded to form the East Branch Reservoir,
part of New York City's Croton watershed reservoir system.
Three thousand feet from the Site to the northeast, Bog Brook,
a tributary to the East Branch Croton River, is impounded to
form Bog Brook Reservoir, also owned by New York City as
shown on Figure 2.
c
The subsurface geology of the area is highly varied giving rise
to an extremely complex subsurface hydrology. Groundwater
throughout the area may be found in both the bedrock and
unconsolidated sediments. In bedrock, the water primarily occurs
in joints and fractures. In the unconsolidated deposits water
exists in the pore spaces. Permeability varies over many orders
of magnitude. The bedrock and unconsolidated aquifers may act
as distinct aquifers, or as one, depending on the degree of
hydraulic connection between the two. Both situations occur
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SITE HISTORY
Beginning in 1954, when Well Field No.1 was developed, the
Village of Brewster has used the aquifers beneath the Village-
owned land, in the Town of Southeast, as a source of water for
its water supply system. In 1967 Well Field No.2 was brought on-
line. The two well fields consist of a total of 18 shallow wells.
Evidence of volatile halogenated organic compound (VHO) contamina-
tion first appeared in 1978, and alternative water sources were
subsequently added to the water supply system, including a deep
bedrock well (DW-2) and two separate shallow wells (SG-1 and
SG-2) located as shown on Figure 3. As a result of low yield
DW-1 was not connected to the supply system. Two new wells SG-3
and SG-4 were added to the system in 1984. Prior to drought
conditions arising in 1981, East Branch Croton River surface
water was also used at times to supplement the water supply
system.
Since 1979, the Village has had several studies conducted to
identify potential alternative groundwater sources and to test
spray aeration as a potential treatment method for VHO removal.
It has since been concluded that treatment of existing sources is
the most promising of the alternatives for solving existing
contamination problems in the Well Field. Under a cooperative
agreement with the EPA, Office of Research and Development, the
Village has constructed, tested and in 1984, placed on line, a
full scale packed column for treatment of the entire Village
supply.
In 1985, a study (Focused Feasibility Study) was conducted by
NYSDEC, to investigate the feasibility of on-Site treatment
alternatives for removal of volatile halogenated organic compounds
from the Village's water supply. Considering cost, reliability,
off-Site releases and flexibility, the packed column was adjudged
superior to other alternatives.
CURRENT SITE STATUS
Concurrent with the Focused Feasibility Study a Remedial
Investigation (RI) was initiated by NYSDEC to determine the nature
and extent of contamination at and in the vicinity of the Site.
Volatile halogenated organic compounds have been the primary
contaminants detected in the groundwater from the Hell Field and
in the vicinity of the Site. Groundwater samples taken during
the RI were analyzed for a wide variety of organic volatiles and
samples from wells DGC-6, DGC-14 and the raw water influent to
the air stripper were subjected to full Hazardous Substance List
(HSL) analysis. The principle contaminants were found to be
tetrachloroethylene (PCE), trichloroethylene (TCE) and 1,2
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Groundwater sampling and monitoring has been ongoing at the Site
since 1978 when VHO contamination was first discovered. Table 1
lists the full range of contaminants and their maximum reported
concentrations discovered at the Site based on RI finding?, NYSDOH
studies and other reports.
Table 2 summarizes the RI analytical data for the most prevalent
contaminants (PCE, TCE, and DCE) by media sampled.
PCE, TCE and DCE are suspected carcinogens and known causes of
liver and kidney damage and central nervous system depression
in humans. Toxicity profiles for each of these principal contami-
nants are provided in Appendix A.
Based on the results of the extensive field reconnaissance, sampl-
ing and analysis of data collected during the RI, the extent of
the contamination at the Brewster ~vell Field can be approximated.
Figure 4 is a schematic of the contamination found at and in the
vicinity of the Well Field in terms of total VHO. The highest
levels of contamination encountered in this area were in groundwater
sampled from RI mon.itoring well cluster DGC-6, in the intermediate
well screened at a depth of 29.7 to 32.2 feet. As evidenced in
Figure 4, other elevated levels of VHOs were also encountered
in the Well Field and in areas south of the East Branch Croton
River. The highest levels are theorized to occur in a relatively
narrow band south of the River, with lower concentrations extending
to the north.
a
The contours shown on Figure 4 were developed based on the
. October 1985 field sampling analysis and hydrogeologic information
described in the RI. The shape of the plume theorized and
represented on Figure 4 was developed incorporating the results
of groundwater analyses and considering groundwater flow conditions
in the Well Field vicinity while the production wells were extracting
water for service to the Village system. The asymetrical shape
of the isoconcentration lines depicts the influence of both
groundwater flow and production well pumping. This configuration
tends to support the premise that contaminants were discharged
southeast of DGC-6 and have moved as a "slug" to their present
position under the influence of natural and Well Field-induced
groundwater flow. The isoconcentration lines in the vicinity of
the Alben Cleaners premises (a suspected source) are subject to
verification because borings were not executed on that property.
Results of groundwater sample analyses from intermediate wells at
RI well clusters DGC-l (screened at 35.7 to 40.7 feet) and DGC-l2
(screened at 35 to 40 feet) indicate low levels of VHO. The
presence of these contaminants at the locations shown on Figure 4
is not fully explained by hydrogeologic conditions and pumping.
Since the concentrations are low, the observed contamination may
simply indicate dispersion of the plume. In regard to the
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(see Figure 4) it is probable that contamination initially drawn
to Well Field No. 1 was drawn directly to the east at the 25-40
feet depth by subsequent pumping in Well Field No.2, SG-3 & 4
and SG-l & 2. Apparently through continual pUMping by wells
SG-l & 2 and SG-3 & 4, contamination has also been moving from the
DGC-6 area directly northeast toward these pumping wells but at
significantly increased depths. Evidence of this is the
concentration and depth of contamination observed in the intermediate
well at DGC-8.
Deep well samples of wells installed during the RI in bedrock
showed no contamination at and in the vicinity of the Well Field.
Based on RI findings groundwater flow is expected to be from the
bedrock to the overlying unconsolidated aquifer under non-pumping
conditions. Under pumping conditions from wells in bedrock (i.e.,
DW-2) hydraulic head is reduced locally and flow from the
unconsolidated contaminated aquifer may be induced into the
bedrock. This would account for contamination detected
in DW-2 which is in close proximity to Well Field No.1.
Sampling and analysis conducted during the RI, in addition to
groundwater, included water in drainlines in the vicinity of the
Site, surface water, private water wells, soil and air.
Discharges from a culvert northeast of Alben Cleaners revealed
average levels of PCE at 88 ug/l, TCE at 14 ug/l and DCE at 6
ug/l based on 134 samples taken. Surface water samples taken at
various locations in the vicinity of the Well Field show isolated
incidents of trace amounts (less than 5 ug/l) of VHO. In the
East Branch Croton River a maximum of 5.4 ug/l of total VHO was
encountered in the vicinity of the Alben Cleaners culvert outfall.
Surveys (including drainline inventories and sampling) of two other
business establishments in the immediate study area, Brady Stannard's
and Savino's garages, indicate that neither are likely sources of
contaminant discharges of the type .ncountered in groundwater
south of the River.
Further downstream toward the 1-84 overpass and beyond I-84
sa~ples from the River showed trace amounts (2 to 4 ug/l) of PCE.
\Jhile these concentrations are low they demonstrate the potential
for an interchange of contaminated groundwater with the River.
Based on the RI results, however there is no significant surface
water contamination at and in the vicinity of the Site except for
the culvert discharge northeast of Alben Cleaners.
Based on 65 private wells water samples high concentrations of
PCE (64 ug/l) were found in the vicinity of the Henry Van Motel,
east and upgradient of the Site. Trace amounts (less than 5
ug/l) of VHO were also found at the Harley Davidson Shop east of
the Site. However, it is not likely that these levels of
contamination are associated with the Well Field contamination,
since a downgradient monitoring well was found to be clean during
the investigation. Monitoring of these facilities was recommended
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During the installation of the RI monitoring well clusters, soil
samples were screened to determine concentrations of PCE, TCE and
DCE at varying depths using a semi-quantitative analysis method
on an HNu 301 portable gas chromatograph. A total of 326-soil
samples were screened as part of the RI field program. Various
degrees of contamination were found in well locations DGC-l, -3,
-6, -7, -8, -9, -12, -13, -14, -15, -16, -17, and -19. Highest
levels of VHO contamination in the soil were found in boring
locations DGC-6 (247 ppb), DGC-7 (71 ppb), DGC-9 (172 ppb),
DGC-17 (44 ppb) and DGC-19 (290 ppb) (see Table 3). These locations
coincide with the maxi~um groundwater contamination levels found
during the RI.
An ambient air monitoring survey was conducted around the Site
vicinity during the RI. Volatiles were not detected in any of
the locations.
Based on hydrogeologic findings (groundwater modeling) and
analytical data for groundwater samples in the vicinity of the
Site, highly contaminated groundwater south of the River is in
hydraulic connection with waters being withdrawn from the Well
Field for Village use. Contaminant levels in the village wells
have never shown total VHOs as high as 5,000 ugfl as discovered
in monitoring \~ell DGC-6. Groundwater modeling shows that this
is due to infiltration f~~m the River and the infiltration channel
near Well Field No. 1 diluting contamination in waters withdrawn
in the production wells. Dispersion caused by pumping from
widely scattered well locations and comingling with uncontaminated
water from other areas of the aquifer also dilute groundwater
. withdrawn from the Well Field.
Based on trends, it is believed that the well Field has reached a
steady state condition, whereby contaminant levels are not expected
to increase at the Well Field in the future.
ENFORCEMENT
~
No negotiations with potentially responsible parties have been
conducted up to the present time. Lack of an obvious source of
contamination has deterred enforcement efforts. The RIfFS has
succeeded in suggesting Alben Dry Cleaners as a probable source.
Enforcement activity will commence, concurrent with the development
of the supplemental RIfFS, to further investigate this probability.
The supplemental RIfFS, recommended in this Record of Decision,
will further investigate suspected source areas and will be
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ALTERNATIVES EVALUATION
The public health and environ~ental objectives of the ~I/FS were
as follows:
°provide a safe, reliable water supply, ~eeting EPA standards,
to the Village of Brewster;
°Contain the plu~e of conta~ination to .~itigate further conta~ination
of public water supplies;
°Restore groundwater quality at and in the vicinity of the
Brewster Well Field to acceptable levels (NYS groundwater standards).
The objective of the proposed supple~ental source control RI/FS
will be to deter~ine which, if any, additional source control
measures are necessary, feasible and cost effective.
Initial Screening Of Alternatives
Re~edial action objectives established for the FS include both'
syste~ objectives (water supply treatment) and source control
objectives (plume containment). The system objectives focus on
control of the quality of the water delivered to the users of the
Brewster supply system. The source control objectives address
means of containment of contamination identified in the plume
area south of the East Branch Croton River and aquifer restoration.
Accordingly, a full range of more than 110 alternative technologies,
and variation of technologies, for treat~ent and source control
were initially screened to determine potential applicability and
appropriateness to the particular proble~s existing in the Brewster
Well Field and its vicinity.
These technologies were then evaluated based on existing
site conditions, including contaminant distribution, geological
and hydrological conditions, technical merit and reliability,
potential effectiveness in meeting remedial objectives, and costs,
in order to establish a final list of candidate technologies to
be considered in formulating remedial action alternatives. See
Table 4.
The technology screening process resulted in a reduced list
technologies judged to be suitable for inclusion, singly or
combination, as components of remedial action alternatives.
Table 5.
of
in
See
These selected technologies were then combined to for~ulate
potential alternative actions that address site problems (i.e.,
groundwater contamination) existing at the Well Field and off-
Site south of the River. This effort resulted in for~ulation of
eleven potential re~edial action alternatives by considering
technologies which address remedial action objectives for both
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Of the eleven alternatives five were eli~inated. The individual
treat~ent syste~s alternative was dropped fro~ consideration due
to uncertainties regarding operation and ~aintenance (~&M) and
high capital and O&M costs.
Alternative water supplies were eli~inated as an option based on
institutional constraints (e.g., constraints on water quantity
supplied by another ~unicipality), potential proble~s during
drought conditions, and high costs.
Groundwater collection, treat~ent and discharge to the River was
dropped fro~ consideration because other alternatives provide the
sa~e benefits of extraction and treat~ent with the added benefit
of e~ploying an innovative groundwater ~anage~ent technique which
would control the conta~ination source by recharge of treated
water to the plu~e area. Additionally, this alternative could
possibly introduce conta~inated water to the River.
Groundwater collection, treat~ent and recharge to the Well Field
was also eli~inated from further consideration due to higher
capital and O&M costs and because it lacks the benefit of
groundwater ~anage~ent to control the contamination source by
recharge to the plu~e area.
50il aeration was eli~inated due to the length of ti~e required
to achieve remediation as compared to soil excavation and removal.
In fo~ulating the final alternatives for evaluation it was
recognized that none of the source control alternatives would be
effective in meeting the water quality objectives required in the
village water supply syste~ without also incorporating treat~ent
in the packed column. Accordingly, the existing packed column
air stripper was included in each of the remedial action alternative
scenarios chosen for detailed evaluation. The final listing of
alternatives evaluated in detail is therefore:
Alternative I -
No action
Alternative II -
Operation of the existing packed colu~n air
stripper
Alternative III - Existing air stripper, groundwater
collection, treatment and injection east
of plume
Alternative IV -
Existing air stripper, groundwater collection,
treatment and injection west of plume
Alternative V -
Existing air stripper, groundwater collection,
treatment and discharge to the existing air
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Alternative VI - Soil handling alternatives
A detailed analysis of these alternatives was then pertor~ed,
consistent with 40 CFR Part 300.68(i). The detailed analysis of
each alternative included refine~ent and specification of
alternatives in detail, with recognition of the reliability of the
use of established technology; detailed cost esti~ation, including
operation and ~aintenance cost, and distribution of costs over
ti~e; evaluation constructability; asses~~ent of the extent to
which the alternative is expected to effectively prevent, ~itigate,
or ~inimize threats to, and provide adequate protection of public
health; and an analysis of any adverse environ~ental i~pacts.
Applicable or relevant and appropriate standards for this Site
include EPA's Maxi~um Contaminant Levels (MCLs), which have been
proposed pursuant to the Safe Drinking Water Act, and New York
State's groundwater quality standards established pursuant to the
Clean Water Act. The applicable proposed MCL for trichloroethylene
is 5 ug/l; the applicable State groundwater standard for trichloro-
ethylene is 10 ug/l.
Contaminant
TCE
TCE
Applicable Standard
EPA Safe Drinking Water Act
NYS Groundwater Standards
Concentration Li~it
5ug/l
10 ug/l
An evaluation of alternatives (which is su~~arized in Table 6)
follows. Co~plete costs associated with these alternatives are
presented in Appendix B.
Alternative I - No Action
For the Brewster Well Field evaluation, the no action alternative
depicted conditions that would exist in the Well Field and municipal
water supply syste~ without the presence of the packed colu~n air
stripper constructed in 1984. Conditions that would exist without
existing treat~ent then formed a baseline against which the other
alternatives were compared. The no action alternative does
assume, however, that actions taken by the community following
the discovery of conta~ination in 1978, such as Well Field ~anagement
to blend waters to control conta~ination and construction of the
new wells on-Site, have been i~plemented.
The no action alternative is completely unacceptable in its
ability to provide a drinking water supply in the near future
meeting EPA MCLs for trichloroethylene. Based on models and
simulations, normal pu~ping of the Well Field would not result in
conta~inant reduction in the Well Field to Sppb levels (assu~ing
no new source) for about 25 years; and groundwater south of the
River would be contaminated at levels in excess of 5ppb for 30-35
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Alternative II - Operation of Existing Packed Column
Air Stripper
This alternative consists of the continued operation of tbe on-
site packed tower air stripper. The packed tower has been designated
by EPA as a Best Technology Generally Available (BTGA) for volatile
organic comounds (VOC) removal from drinking water (40 CFR 141
and 142) and has been extensively tested and proven at the Brewster
site. Removals of contaminants have been reported at 99% or more
and levels meeting EPA MCLs have reliably been met. Therefore,
this alternative will exceed applicable or appropriate and relevant
standards, providing a very high level of public health protection
with respect to the Village's water supply. This alternative
does not include source control measures.
Times to restore groundwater quality at the Well Field and area
south of the River would be the sarne as Alternative I.
Gaseous emissions from the air stripper consist of extremely low
levels of volatiles which will pose no chronic or subchronic
health threats to downwind receptors (e.g., worst case PCE
concentrations at the top of the stripper are estimated at 1.6
ppm versus 8 hour Threshold Limit Values of 50ppm recommended by the
American conference of Governmental Industrial Hygenists).
Alternative III - Existing Air Stripper, Groundwater Collection,
Treatment and Injection East of Plume
This alternative assumes that Alternative II (treatment of the
. existing public water supply by an on-Site packed column stripper)
would be implemented and, additionally, assumes that remedial
facilities would be constructed in the area south of the River.
These facilities would include extraction wells, an additional
packed column stripper to treat extracted water (to 99.9% removal
of VOCs) and passive injection wells east of the plume area. See
Figure 5.
Groundwater modeling of the collection/treatment/recharge system
indicate that the quantity of water from the producing wells at
the Well Field would not significantly be affected. Simulations
also predict that contaminant levels of 5ppb or less could be
achieved at the Well Field and in groundwater south of the River
in about 10 years with collection/treatment/recharge.
Alternative III, therefore, presents a solution to the source
contamination problem by meeting the objectives of plume contain-
ment and restoration of aquifer quality as well as reducing long
term public health and environmental risks by remediating the
contaminated public water supply.
Extraction and injection wells and the air stripper could be
installed with no adverse impacts on New York State regulated
wetlands and with minor impact to areas classified as wetlands
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i~pacts would be expected fro~ the air stripping process. The
passive injection wells would require approval from the EPA as
Class V wells under Underground Injection Control regulations
pursuant to the Federal Safe Drinking Water Act.
Since ~uch of the work conte~plated south of the River is on
lands under control of the City of New York, City 'approval would
also be required. The benefit of cleanup would accrue to the
City as well as the Village and, as a result, approval would be
anticipated.
Alternative IV - Existing Air Stripper, Groundwater Collection,
Treat~ent and Injection West of Plume
This alternative consists of the sa~e technology components identi-
fied in Alternative III. The difference between the alternatives
involves the location of the injection wells. In Alternative IV
extraction wells would be placed on the eastern side of the plume
area, with injection wells to the west. As in the case of Alterna-
tive III an on-Site air stripper, to treat the Village water
supply, is also assu~ed. See Figure 6.
This scenario was identified during analytical modeling as poten-
tially the most effective. Flushing of water across the most
contaminated areas is enabled and a hydrodynamic barrier is placed
down-valley from the plu~e. However, without 100 percent treat-
ment efficiency (estimated at 99.9%) some injected water with low-
level (5.6 ppb) VHO contamination would probably flow downgradient
and some of the water injected on the west side of the plume area
may be lost downgradient to the west, out of the vicinity of the
influence of the Well Field production wells. Further, the pre-
cise location of the western boundary of the plume is not yet
known, ~aking monitoring of this alternative difficult.
Otherwise this alternative is similar and judged equal to Alterna-
tive III. Groundwater restoration times would be equal to Alterna-
tive III (10 years).
Alternative V - Existing Air Stripper, Groundwater Collection,
Treatment and Discharge to Existing Air Stripper
at the Well Field
Alternative V includes an on-Site packed column air stripper, the
sa~e as Alternatives II, III and IV. Similar to Alternatives III
and IV, extraction and treat~ent, in an off-Site stripper, of
water from the conta~inated plume area south of the River is also
assu~ed. Under this alternative, however, no injection well would
be used. Instead, the treated effluent from the off-Site stripping
column would be piped to the on-Site treat~ent system for further
treat~ent along with water from the Well Field production wells.
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-11-
The performance of the on-Site stripper, in re~oval of VHbs fro~
the public water supply, would be excellent as long as the ef-
fluent from the off-Site stripper contains VHO levels equal to
or less than levels encountered in water fro~ the production
wells. Accordingly, State standards and proposed Federal MCLs
should be met. In regard to source control objectives, the
extraction and treatment of groundwater from the source area
south of the River would contribute both to contain~ent and
restoration objectives. Projected beneffts to groundwater quality
are similar to Alternatives III and IV. However, extraction without
reinjection in the area south of the River may result in a slightly
longer period for restoration of groundwater quality, when co~pared
to Alternatives III and IV.
In order to ensure that the off-Site stripping system is working
properly to produce an effluent amenable to mixing with waters
from the projection wells extra precautions would be necessary.
At the off-Site stripper this would be provided by additional
controls and more frequent ~aintenance and monitoring. These
additions are reflected in additional costs.
Risks exist in this alternative of possibly inducing a new class
of pollutants into the source of Brewster water supply. For
exa~ple, if yet undetected non-volatile contaminants exist in the
groundwater south of the River they could be drawn into the syste~
and not removed by the air strippers, because air stripping
is effective only on volatile compounds. At a minimum, full
monitoring for all Hazardous Substances List (HSL) compounds
would be required on a periodic basis to avoid this
possibility.
This alternative would require a pipeline crossing under the
River (with probable adverse environmental impact) and a
physical hookup to the raw water feed line of the on-Site stripper.
In addition, certain institutional approvals would be required
from the State, the City of New York and the Village of Brewster.
The complexities involved in i~plementation of this alternative
makes it less attractive than other alternatives.
Alternative VI - Soil Handling
Soil contamination alternatives are addressed separately because
these actions may be implemented as part of any remedial action
plan. The objectives of the soil contamination alternatives
are to identify zones of soil contamination or residues that ~ay
be contributing to groundwater contamination and identify the
~eans to eliminate such sources, if feasible.
Meeting these objectives would require two steps: first,
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-12-
The most likely source of VHO contamination identified during the
RI is the premises of Alben Cleaners. However, no confirmation
of the existence of localized contamination in the Alben Cleaners
area was provided during the RI studies. In order to identify
whether a continued source of contamination exists on those
premises a program of test pitting, shallow well installation and
contaminant analysis would be undertaken.
If soil contamination is encountered in significant levels, a
program to excavate the soils in the unsaturated zone would be
carried out. For purposes of estimates it was assumed that an
area about 43 feet wide by 80 feet long by 6 feet deep would require
excavation east of the Alben Cleaners building. Several options
exist for soils handling under these conditions, depending on
contamination levels encountered. For example, soils could be
loaded and transported off-Site to a secure (RCRA approved)
landfill. Soils could also be treated on-Site using rotary kiln
or infrared incineration. Data from the supplemental RI/FS will
assist in further evaluating this alternative.
Any of several innovative soil remediation measures could be
effective in achieving the stated objectives depending upon the
type and quantity of contaminants present. Off-Site disposal
could be accomplished relatively easily, while on-Site soil
remediation would be more difficult to implement. All alternatives
could be carried out in accordance with environmental regulations.
RECOMMENDED ALTERNATIVE
. The appropriate extent of remedy shall be determined by EPA's
selection of a cost-effective remedial alternative that effectively
mitigates and minimizes threats to and provides adequate protection
of public health and welfare and the environment. This will
normally require selection of a remedy that attains or exceeds
applicable or relevant and appropriate Federal and State public
health and environmental requirements that have been identified
for the Site.
Discounting the no action alternative (since the packed tower air
stripper is already in place), each of the alternatives selected
for detailed evaluation would provide an appropriate extent of
remedy within the above definition. Based on meetings with New
York State, its consultants, the Village of Brewster and the
public, it is recommended that continued operation of the existing
air stripper to treat the Village's water supply and design and
construction of a groundwater management system to contain the
plume of contamination and restore groundwater quality south of
the River, be selected as the remedy for this project. The
groundwater management system will include groundwater extraction
wells, air stripper treatment of extracted groundwater and
reinjection of treated water. Details of the groundwater management
system will be determined during design.
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-13-
This alternative provides a safe and reliable water supply to the
Village that exceeds applicable or relevant and appropriate
standards, thereby providing a very high level of public health
protection. This alternative will also restore groundwat~r
quality south of the River to levels exceeding applicable State
groundwater standards.
Detailed cost estimates for the recommended alternative are
included in Apendix C.
COMMUNITY RELATIONS
Community perception of the Brewster contamination problem has
been an important factor in placing this site on the Superfund
National priorities List. VHOs were discovered in the Village's
water supply in 1978. Considerable local press regarding the
issue contributed to public awareness.
Since the NPL listing in December 1982, public concern has subsided,
and the townspeople have been generally satisfied that appropriate
action is be.ing taken and that no contaminated water is being
consumed. However, there is still concern regarding the potentia1
spread of contamination.
Specific concerns that were raised during the public comment
period are answered in the Responsiveness Summary. All comments
were made at the public meeting held on August 21, 1986 at the
Brewster Village Hall. No other comments, writtten or otherwise,
were received during the public comment period.
CONSISTENCY WITH OTHER ENVIRONMENTAL LAWS
At the present time, there are no Federal environmental laws
other than the Safe Drinking Water Act which are applicable to
implementing the selected remedial action at this Site.
Trichloroethylene has been chosen by EPA for evaluation and pos-
sible future regulation pursuant to the Clean Air Act's National
Emission Standards for Hazardous Air pollutants (NESHAP). However,
such regulation will likely not be promulgated for 1-2 years. At
the present time, EPA believes that the risk assessment performed
for the operation of the packed column air stripper (using worst
case assumptions throughout the analysis) has sufficiently demon-
strated the extremely low risk associated with the predicted
level of air emissions on likely receptor areas.
OPERATION AND MAINTENANCE
Packed column technology has been successfully applied for removal
of VOCs at full scale water treatment plants in at least 24 locations
in the United States. The equipment is commercially available:
-------
-14-
accomplished quickly: and the equipment can be designed to operate
for a number of years. It has also been shown to operate under
varying climatic conditions. The existing Brewster on-Site air
stripper has successfully been operating for more than a ¥ear.
Costs estimates for the operation and maintenance of the on-Site
(water supply) and off-Site (groundwater remediation) systems of
the selected remedy are included in Appendix C. EPA will not
participate in the cost of operating and maintaining the existing
on-Site air stripper. Said costs are to be. borne by the Village.
FUTURE ACTIONS
A second operable unit consisting of additional source control
remedial measures may be implemented following the supplemental
-------
FIGURES
-------
-15-
TO
ALBANY
CATSKILL
PARK
o
""'~:; ;;1
'" " \ .
.~ .......... HUDSO~' ~
"".. RIVER
....
....
......
.... .
..
...
....
....
...
..
,
,
,
...
FIGURE 1
REGIONAL lOCA riON
APPROXIMATE SCALE 18-14 MILES
,
,
,
I
,
I
,
\ MASS.
\-------
, CONN.
,
I
,
I
I
,
I
I
I
I
,
I
, BREWSTER
I WELL
I FtE.LP
I
I
,
-------
-16-
t
SCALE 1:24000
o
I MIL[
1000
-
o
1000
2000
JODO
o
~
~
taX)
'000 '(['1
.
I
-
s
.- -
-
I .'~O"U(.
CONTOUR INTERVAL 10 FEET
OATUM 1\ M(AN SEA I.EVIL
\~~
/" ..(w 'OQ. .
'- -- ""'\ (
. ~
JREWSTER. N. Y. -CONN.
N4122.~--W 7330/7.~
1958
I'HQTOR(VISlO 1970
15 6266 I NE - SEI'IES Vl21
FIGURE 2
BREWSTER STUDY
AREA LOCA TION
~. 1:-
-------
-17-
,
\ ~ - -- -\ VILLAGE OF
- -~ ~ 8REWSTER
- j '\ PROPERTY LINE -
~ : <>D.~:~"!Ell "'El .. /
-------
-18-
~
..
FIGURE 4
ISOCONCENTRATION MAP, TOTAL CONCENTRATION OF
VHO AT MONITORING WELL LOCATIONS
BASED ON SAMPLE ROUND NO.1 COCTOBER,1885)
LEGEND
, - 'ILL
T - GLACIAL TILL
GL - GLACIOLACUSTIUNI
D - GLACIO'LUVIAL-OIL TAlC
OW - GLACIO'LUVIAL-OUTWASH
SG. $ANC'/G"'AV!!.. ~Upp~V We~~
ow- peeP ~cJPPL"" wa:.
OOC-' MONITOIltINO WILLI
('0-20) ICIltIINID INTI.IltVAL TO NIAIltI'T 'OOT
,. - TOUL VHO
-------
-19-
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-------
-20-
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-------
-21-
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' , ~) ) 11\, \"" " .. ~ -," ", "-",,;, ':"-,' ';.. / I '(...', ,.'
' ' , I "', .." ...t,;"., ..:'>,":',, '" ,.'::, ..;, ''') " ) ,.,' ',',
\ ' I ""'. ,'"" . - , - , ,,\~' " /' ,
-, II ~ ',' ~. , ,'" , " '" " ,
'\" , to'~, , " ,',' ',".. I' ,
' \\ / II J!jl //"...c"",-Y ,J.' , ", ,': ';"""," :: .;0 / ( ,',
- , 1/ ."'''' ,,-.' . "'" '! / ",
" , \ / I Y (; "', ,:', ,',', '. , ' , ' , , '.' ' , . ','
~"\//~~/~
-------
-------
TABL( 1
MAXI.... R(PORT(O tONTAHINATlON IN WmUhlJWAT(H
RI ANO PR(VIOUS SIUOI(S (ug/l)
MAX I....
CON((NTRA HON
ug/l
OTHlR M(SUl TS
CONTAHINANT
TetrAChloroethylene
5600
5600 ug/l reported in Well 61 on 10/30/85 (Co8puChe.,.* Il.500 ug/l reporteo in a
S.-ple taken fro. Well 61 on 4/15/86 (HNU 301 Screening). In a s.-ple taken
10/8/85 fro. Well 61. I concentration of 10.600 ug/l ~as reported (""U 3~1
Screening) .
550 ugll reported in a s.-ple taken 12/21119 fro. TH 112 (100 feet N( of the
location of Well 61) (H2")**. 120 ug/l reported in s.-ple taken 10/22/85 fro.
Well 61 (C~Che8). 224 ug/l ~as reported in I S.-ple taken 10/8/85 fro. Well 61
(HNO 301 SCreening).
Trichloroethylene
550
cis-I.2-Dichloroethylene
950
950 ug/l reported in a S.-ple taken fro. TH 112 on 12/21119 (H2H)**. In the
distribution syste8. 22 ug/l ~as reported in a Sl8ple taken 4/14/81 (HzM). In
Well field No. I. 89 ug/l ~as reported in a '.-pIe taken 9/30/82 (HzM).
210 ug/l ~as reported in a s.-ple taken fro. Well 111 on 10/30/85 (C08puChe8).
I
N
N
I
trlns-I.2-Dichloroethylene
Carbon tetrachloride
210
A revie~ of all .vail.ble data fro. the RI and p.st reports Sho~d no detectable
levels of c.rbon tetrachloride. The RAMP Report (NUS. 1983) indicates. 5 ug/l
concentration in the data. but the SourCe of th.t ~.t. is unkno.n. . It is presU8ed
that reporting of the data should have inclUOed . -less than- sign in the RAMP
compi I.t ion.
I.I.I-Trichloroeth.ne
23
23 ug/l ~.s reported in Deep Well No.2 on 4/21119 (O'8rien 'nd Gere). 8 ug/l ~as
reported tn the distribution syste8 on Il/l3118 .nd 1/16/80 (hY~UH). 4~0 ugll ~as
reported in . sa.ple collected 10/5118 .t the Bottge sept.ge oisposal site. It is
not known Nhether this w.s . grouno.ater sl8ple or I grab s.-ple taken .t the
surfACe (NYSOHI).
404 ug/l reported in a Sl8ple taken 10/5118 fro. Well field "0. I ("YSDh) (kells
were being chlorinated It th.t ti8e). 16 ug/l ~.s reported in the distribution
syste8 5/21/80 (NYSOH).
Chlorofora
404
*
Co.puChe8 is ConpuChe8 Laboratories; H1M is H2" Corporation Laboratories; NYSDH is N~ York State Department of health
laboratories; HMU 301 Screening is field GC Screening by GlIR Engineering Associates using an ""U 301 GC.
**
,
Putn~ County Health Department notes that certain test holes sanpled in 1919.ay have been cont4minatea with pipe
-------
TABLE .1
(continued)
~XI"" REPONTEO CO,nMINAHON I" GROUJlIlWA1ER
RI AND PREVIOUS STUDIES (ug/l)
~XI""
CONCENTRA T ION
ug/l
OTHER RESUlTS
CONTAMINANT
lrc80fonl
Ir08Odtchlor08eth.ne
J
3 ug/l reported tn the distribution syste. 4/1~/81 .nd 5/13/81 (HzM).
49 ug/l reported tn Well Fteld No. I on 10/6/78 ("'SOh). (Wells were being
chlorln.ted .t thts tl8t). 24 ug/l reported In the distribution syste. 8/1~/80
("YSOH). 10.1 ug/l reported In the distribution syste. 12/1118~ ("YSOH).
49
Chlorodlbr0808eth.ne
I)
13 ug/l reported In Well Field No. I 9126/78 ("YSOH) (Wells were being chlorinated
.t thts tl8t). 10 ug/l reported In the dlstrlbutton syste. on ~/2'118. 11/20/18
.nd 5/13181 ("'SOH). 11 ug/l reported tn Well Fteld hOe i 1/11179 .nd 8/14/80
("'SOH) .
I.2-Dtchloroeth.ne
3
J ug/l reported tn dlstrtbutton syste. 1011180 (HzM). The presence of this
C08pOUnd ~.s not detected in .ny other sl8ples b.sed on InfOnl.tlon .v.II.ble to
d.te.
Vtnyl Chlortde
20
20 ug/l reported In salple t.ken from Well 191 on 10/30/8~ (108puChe8). Vinyl
chloride reported In sl8ples taken 10/J0/8~ .t 6 u9/1. ~.4 u9/1 .na 1.0 ug/l 1n
Wells 91. 11 .nd 31. respectively (C08puChe.). Vinyl chloride .t 2 ug/l was
reported tn the distrlbutton syste. on 2/11/81. 4ll~/81. ~/13/81 .nd I ug/l
8121/80. 8/25/80. 1011180. 12/4/80. 119181. 5/6/81 .nd 2/9/81 (H2"). 10 ug/l
reported tn Well field No. I 11/19/80 (H2"). In 25 sl8ples fr08 Well fielo fIo. I
collected 1125/80 - ~/J0/82 for .n.lysts by H2M. 23 sl8ples showed vinyl chloride
In the range of I ug/l to 10 ug/I .nd .ver.ged 5 ug/l. .
130 ug/l reported In s.-ple fr08 Well 19S 10/30/85 (C08puChe.).
I
rv
w
I
Benzene 130
Toluene IIQ
Ethyl Benzene 24
Xylenes 1300
1.2-Dtchloroprop.ne 10
110 ug/l reported tn sl8ple fr08 Well 19S 10/30/85 (C08pUChe.).
24 ug/l reported tn s.-ple fr08 Well 19S 10/30/85 (Co.puChe.).
1300 uglt reported In Sillp Ie fr- we II 19S 10/30/85 (C08pUChe.).
Reported In sillple 10/23119 (HZM) observ.tlon well 16... Detected in samples fro.
Well Field No. I .t Z ug/l in 4 sc)lllpies .nd .t I ug/l In 5 slqlles In the perioD
1125/80 - 11/19/80 (HzM). Reported In Well field No. i .t I u9/1 4/1111~ .no
-------
T ABU I
(colltlnued)
HAXlI1UH RlPOHHO CONTAMINATION IN l>ROUNOWAHR
RI AND PRlVIOUS ~IUDI(S (ug/I)
MAXIMUM
CON((NIRAT ION
ugll
OTl1lH HlSULT~
CONTAMINANT
Diethylphthalate
140
140 ug/I reporteo In a priority PQllutant sample taken IU/7/uu IhZ"/.
1,I,2.2-Tetrachloroethane
31
Reported In sample taken lilli/lib, Well 17~ (Co""ulllemJ.
contained 1.3 ugll IU/30/tiS (lompulheml.
Reported in a sample taken 10/30/85", Well 61 (ClAlpuChem).
Une other selmple
bis-(2-ethyhexyl) phthalate
I.I-Dichloroethylene
1
25
25 ug/l reported in TeH lIole 11'-' 12/21/19 (H2M).88 I.] ug/I reporteo in selmple
frOll Well 3S IIlB/llb (CocnpuChea). Une other sample taken 1nu/til from Well Flelo
No. I showed I.I-OC( elt lug/I.
Reported in a sample from Well field No. I 1/25/80 (112").
I
N
..,.
I
trans-I.]-Oich10ropropene
4
Oi-n-butylphthalate
5
Reported in saMple taken 10/22/85, Well 141 (C~pu Chem). 3.0 ug/I and 3.4 ug/I
reported in samples ttken 10/22/85 from Well 61 and air stripper influent
respectively (Compu Che~).
N-nitrosodiphenylamine
2.B
-------
-25-
TABLE 2
SUMMARY OF RI ANALYTICAL DATA
FOR CRITICAL CONTAMINANTS
MEDIA
=========================================================================
PCE
1,2-DCE
Groundwater-
/- reQuency( 1 )
Maximum Level (ppb)
Average (PPb)
Groundwater-*
Frequency
Maximum Level (ppb)
Average (ppb)
Surface Water (Croton River)
Frequency.
Maximum Level
. Average
TCE
13/44 10/44
5600 100
696 47
12/19 9/19
3900 67
668 37
3/29 0/29
4
3
7/44
210
107
8/19
160
68
0/29
Surface Water (Cu1 vert Oi scharges)
Frequency 108/135 101/135 100/135
Maximum Level 1000 136 37
Average 102. 1 16.8 5.9
Soils
Frequency 59/326 41/326 46/326
Maximum 280 46 21
Average 28 5.5 3.3
==========================================================================
* CompuChem Results
**CompuChem Results
(1) Shows Number of
Samples Taken
- Sample Round 1. (1985)
- Sample Round 2. (1986)
-------
IA8LE )
H6~~~r~:~~I~~I~~~~~~S
HNu 301 SCREEHIHG kESULTS (ppbl
---
P[PTH
~lLL 61 ~
ICE 1,2-0([
0-2 I.] O. I
2-4
4-6 0.5
6-8
8-10
10-12 3.] 18
12-14 2.0 1.0 1.0
14-16 4.9 3.6 2.1
16-18
18-20
20- 22 4.1 1.8 0.1
22-24 2.0
24-26 2.0 1.0 0.]
26-28 2.0 ].0
28-30 2.0 1.0
30-32 2.0 2.0
]2-]4
34-36
36- J8 3.0
38-40 3.0
40-42
42-44
44-46
46-48
48-50
50-52
52-54
54-56
56-58
58-60
60-62
62-64
64-66
66-68
68-10
10-12
12-14
14-16
16-18
18-80
~n
WELL 11
Te[ 1.2-DC[
PC[
WELL 31
Tn '.2--0(£
P(£
WELL 61
TCE 1.2-0(£
0.3
0.2
34 46 4.]
126 10 1.5
242 4.0 1.0
111 1.3 0.5 1.0
39
22
15 0.6 0.2 20
3.0
1.1
1.3
3.3
1.1
P([
W!LL 11
TCE 1.2-0([
PCE
I
rv
21 m
0.] I
8.0
6.0 3.0
II 11
8.0 5.0
1.0 5.0
0.1 0.3
0.1» O.l O.O!l
1.5 0.5 0.1
2.42 .94 0.4
19 1.0 2.1
0.1 0.2 0. 1
j
H.
-------
. .
TABU. J
(continued)
SEHI-QUANTITATIVE ANALYSIS
MONITORING WELL SOil SAMPLES
HNu 301 SCREENING RESULTS (ppb)
O£PTH
PU
w~~~ 9I'.1-0C£
Pc[
~Ell t~1
TC£ 1.1-0C[
PCE
WHl I~I
tCE 1.?-OC[
PC[
WEll 141
TCE 1.2'-0([
PC[
WELL I~I
TCE 1,2'-0([
0-2
1-4
4-6 1.4 0.7
6-8
8-10
10-12 O.!» 0.4
12-14
14-16
16-18 O.b
18-20
10-22
22-24
24-26 6.0 1.0 0.5 0.4
26-28
28-30
30- 32 28 5.0 3.0
32-34
34-36 136 21 15 3.0
36-38 6.0
38-40
40-42 96 17 10 2.0
42-44
44-46 22 3.0 2.0
46-48
48-50
50-52 2.0 1.0 0.5
52-54
54-56 0.3
56-58
58-60
60-62
62-64
64-66
66-68
68-70
70-72
12-14
14-16
16-18
18-80
I
IV
-.J
I
-------
..----- --
1 A8U 3
(cont inued)
~UANII1AIIV[ ANALYSIS
IHG ~£LL SOIL SAKPLLS
HNu 301 SCR[[NING R£SULI~ {ppbl
O[PTH
PLWl
WUL 161
TCE 1.2-0C
PLRC
. WUL 171
Tcr I,l-on
P£RC
~£Ll 191
1([ 1,2-0([
P(I((
WUl
1([
1,2-0([
0-2
2-4
4-6
6-8
8-10
10-12 12.9 8.4 6.3 6.0
12-14
14-16 21 8.6 8.S 3.0
16-18 104 14 6.0
18-20
20-22 9.0 3.1 2.1 280 1.0 3.0
22-24 13
24-26 O.S O. I 4.3 1.2 0.9 66
26-28 18
28-30 11 O.S 0.2
30-32 16.4 4.0 3.6
32-34 .9S .34 .44 S3
34-36
36- 38 3.3 0.1 0.4
38-40
40-42
42-44
44-46
46-48
48-S0
50-52
S2-S4
S4-56
56-58
58-60
60-62
62-64
64-66
66-68
68-10
10-12
12-14
14-16
16-18
18-80
I
tv
00
I
~[: ONLY SAMPLES SHOWING VHO CONTAMINATION ARE R£PORT£O IN TH'
-------
-29-
-rA6Lc 4
~~ D1DA\E: REMEDIAL A~TIDN TEc~NoLo:'"«(ES
TECHNOLOGY
8Z========================================================================
REMEDIAL OBJECTIVE
Containment Barriers
o Slurry Walls
o Vibrated Beam Walls
o Grout Curtains
o Sheet Piling
Groundwater Pumping
o Extraction Wells
o Injection Wells
Soil and Waste
Excavation and
Removal
Rotary Kiln Incinerator
Infrared Incineration
Activated Carbon
Treatment
Packed Column
Aeration
APPLICABI L!TY
May be effective in
plume containment if
geological conditions
and contaminant
capatibility warrant
May be effective in
plume containment
and aquifer cleanup
May be effective in
eliminating a source
of contamination in
plume area
Could be effective
in elimination of
contaminants in soil
or material excavated
in source area
Could be effective in
elimination of
contaminants in soil
or material excavated
in source area
Could be effective in
treating water for
water supply system,
for treatment of
groundwater extracted
in plume area and
for reduction of
emissions from air
stripping columns
Effective in treatment
of water for water
supply system and
for treatment of
groundwater extracted
in plume area
Source Control
Source Control
Source Control
Source Control
Source Control
System Control and
Source Control
System Control and
-------
-30-
"T'ABLe.4 <~NI'P)
CAN-DIOA,,:. ~~EL:>IALAc.TIO~ 1"E~HNO~\E:~
TECHNOLOGY
==z=========..=.==========================================================
REMEDIAL OBJECTIVE
Drying/Dewatering
Bed
Landfill
Alternative Water
Supplies Sources
o NYC Reservoir
o River Intake
Individual Treatment
Units
APPLICABILITY
Could be effective in
handling soils or
materials excavated in
Source area
If excavation of soils
or material is under-
taken in plume area,
it may be necessary to
dispose of materials
in approved landfill
May be feasible if
institutional and
technical constraints
are resolved
May be feasible if
costs and other
technical constraints
are resolved
Source Control
Source Control
System Control
-------
-31-
TABLE ~
====.========================.===========================================
~H~.L~IES -Si:Li:Crt=D A?
COMPONENTS OF REMEDIAL AlTERNATIVE~
Groundwater Pumping
Extract i on We 11 s
Injection Wells
Soil & Waste Excavation and Removal
Backhoe
Dewatering
Drying or Dewatering Beds
l'and Disposal
Secure Landfill
Incineration
Rotary Kiln
Infrared
Treatment of Liquid Waste Streams
Packed Column Aeration
Alternative Water Supplies
Reservoir
River
-------
TAiLE G
EVAlUATION Of REMEDiAl ACTION AlTERNATIVES
IR£WSTER WELL fiELD
SUMAJt Y
ALTERNATIVE
[[[
TE(HNICAl CRITERIA INSTITUTIONAl PUBLIC ENVIRONMENTAl PRESENT
PERfORHANCE RELIABIL ITY IHPLEMENTAB IL ITY SAfETY fACTORS HEALTH fACTORS WORTH (4)
II
No Action Not Mugln.1 Good I
Accephbl e
I
OperltiOft 01 the e.istlng hce I hnt (1) heellent hee 11 ent
p.cked colU8n .Ir stripper Mugin.1 m
fllr "ot "ot M.rgln.1 O(S)
AcceptAble AcceptAble
Good hcel1ent (l) hcelhnt Good $189 .000 ('5)
Margln.1 0)
Good Good (1) hcellent Good $512.000
Good U)
III
Good
Ealstlng Air Stripper.
ground... te r co 11 ec 16 on .
tre.blent .nd Injection
fISt of plu-
Excellent (2) Good
Good lJ)
IV
$"12.000
Ealstlng Air Stripper.
ground... ter co 11 ec t ion.
tre.t8fnt .nd Injection
west of plU8e
hcell ent Q) Good
Good ()
Good
Good
Good (l)
flld))
heellent Good
V
fllr
$558.000
I
w
IV
I
VI
E.lstlng Air Stripper.
ground... ter co II ec t i on .
tre.blent .nd dlsch.rge
to the ealstlng .Ir
stripper .t the Well Field
hcel hnUl) fllr
fllrU>
fllr
fllr
fllr
Good
~.
5011 Cont..ln.tlon Altern.tlves - One of these alternatives Is .ssU8fd to be plrt of any relledl.1 .ctlon plln. If .
cont..ln.ted soil source Is Identified. These costs .re not Included In
the costs st.ted .bowe.
Off-Site Olspoul
On-Site Rotlry Illn Inclner.tor
On-Site Infrared Inclnerltor
$194 .ID"
$990.]75
$110.000
ill "ot Iccept.ble fnNI regulatory stlndpolnt
(2) In te,.s of syste8 objectives
O)ln ter8s of source control obJectlwes
&4) I nc I udes present .orth 0 f 0 & "
6)The present worth or cost of this .Itern.tlve Is zero In the c08parltlwe .nllysls fr..e.ork estlbllshed for the felslbility Stud,. In
Ictu.llt,. the option for "0 Action does not ealst becluse . trelblent syste8 (ealstlng packed colU8n Ilr stripper) h.s .Ireldy been
Inst.lled It the Site.
-------
-------
-33-
~ppenaJ. ~ i\
Tetrachloroethylene
Chemistry and Metabolism
Tetrachloroethylene (perchloroethylene) is a halogenated aliphatic
hydrocarbon of molecular weight 165.83.
Oral absorption data is scanty and qualitative.
An early study
noted that intestinal absorption in dogs was facilitated by fats and
oils.
In humans, pulmonary absorption is rapid and inhalation is
the most common exposure route.
While metabolism of
perchlorethylene is fairly slow in humans, metabolic products, such
as the reactive PCE epoxide, have been shown to be both carcinogenic
and mutagenic, embodying much of the risk potential of the parent
compound (EPA, 1986).
Low percentages of doses are reported as
being excreted as metabolites, principally as trichloroacetic acid.
Toxicity
Tetrachloroethylene is considered a probable human carcinogen.
A
cohort study of deceased laundry and dry-cleaning workers' medical
histories revealed excessive lung, cervical, and skin cancers, and a
slight excess of leukemias and liver cancers, but the subjects'
exposure to trichloroethylene and carbon tetrachloride in addition
to perchloroethylene precluded definitive identification of the
causal role of perchloroethylene.
-------
-34-
PCE's carcinogenic potential resides ptimarily in its biologically
reactive metabolites such as the PCE epoxide intermediate (EPA,
1986).
A 1977 ingestion study using rats and mice reported
decreased survival rates in both species and highly significant
increases in hepatocellular carcinomas in the mice.
was observed for rats).
(No increase
A 1985 (draft) National Toxicology Program lifetime inhalation
bioassay with rats and mice demonstrated that perchloroethylene
induced carcinogenic effects in rats and mice.
Although EPA
acknowledged that certain aspects of the conduct of the bioassay.
might invalidate a reported marginally statistically significant
leukemia incidence in one strain of male rats, the two sets of
animal studies were considered to provide evidence justifYing
alteration of the previously developed carcinogenic risk factor in
March, 1986.
inhalation in three ranges.
The 1985 NTP study data were used to estimate unit risk of PCE via
derived from a single exposure balance study and the second and
third ranges are calculated on the basis of metabolized doses
The first range uses metabolized dose
derived from a Physiologically-based pharmacokinetic (PB-PK) model.
Until uncertainties regarding PB-PK model parameters are resolved,
EPA recommends using the first range, which Yields a revised upper-
bound estimate of incremental cancer risk (due to lifetime exposure
of 1 ~g/m3 of PCE in air) ranging from 2.9 x 10-7 to 9.5 x 10-7.
-------
-35-
(This is applicable only to low level exposures where a linear
relationship exists between ambient concentration and metabolized
dose.)
In September 1985, EPA published a carcinogenic potency factor for
humans of 5.10x10-2(mg/kg/day)-1. ACGIH (1983) recommended a TWA-
TLV of 50 ppm and a STEL of 200 ppp, while OSHA has implemented a
permissable exposure level (8-hour TWA) of 100 ppm (CRF, 1981).
In humans, chronic inhalation exposure to a range of
perchlorethylene concentrations have been reported to lead to
respiratory irritation, nausea and other intestinal effects,
insomnia, headache, liver cirrhosis, hepatitis, and nephritis,
although dose levels were not quantified.
Effects of subchronic inhalation exposure to perchlorethylene in
experimental animals include a number of histopathological and organ
function alterations.
For example, rats showed EEG changes and
cerebral cortical cell changes, liver and spleen congestion and
kidney injury.
Mice demonstrated alterations in muscle response
while rabbits showed pathomorphological and organ function
abnormalities.
Guinea pigs are unusually susceptible to
perchlorethylene, according to evidence from studies which found
pathologic.changes in both liver and kidney at doses lower or
comparable to those which induced no eviden~e of damage in monkeys,
rabbits or rats.
-------
"-36-
'.
Little information exists regarding chronic toxicity due to
perchlorethylene exposure.
In a 1977 NCI oral carcinogenicity
bioassay with mice and rats, toxic nephropathy was observed at all
dose levels in both sexes of both species, leading to establishment
of LOAEL's for toxic nephropathy of 300 mg/kg/day for mice and 471
mg/kg/day for rats.
Unspecified reversible liver damage was
reported.
Other aspects of tetrachloroethylene toxicology include
teratogenicity and potential interaction with other toxicants.
Teratogenic effects were found in two species of rodents when 300
ppm was administered via inhalation for 7 hours per day during a
portion of the gestation period.
Tetrachloroethylene toxicity is believed to be affected by compounds
. that alter microsomal enzyme function, because of its metabolism by
mixed function oxidases.
Synergistic effects have been demonstrated
with Arochlor pretreatment, with alcohol, and with benzene.
In the few reports available, perchlorethylene has elicited mixed
responses in mutagenicity tests.
Results were positive in tests
with two Salmonella assays, but were negative with Escherichia £2li
and with bone marrow cells in intraperitoneally injected mice.
-------
-37-
Trichloroethylene
Chemistry and Metabolism
-
Trichloroethylene (TCE) is a halogenated aliphatic hydrocarbon of
molecular weight 131.5.
The metabolism of trichloroethylene has been reviewed by numerous
authors.
Although oral absorption rates are not available for
humans, rats were found to absorb 80-100\ of ingested TCE.
Human
absorption of inhaled TCE is rapid, leading to. equilibrium body
levels in roughly two hours.
Major metabolites of TCE are trichloroacetic (TCA) acid and
trichloroethanol.
Other minor metabolites noted in the literature
include chloroform and monochloroacetic acid.
Of these,
trichloroethanol is excreted in the highest volumes and has itself
been found to have a pronounced depressing effect on the central
nervous system.
Given the long biological half-life of TCE,
cumulative effects of the parent compound and the metabolite may be
very significant.
Ikeda and others (1972) found that workers
exposed to 100 ppm TCE excreted only one third of the dose as
metabolites during the work day, while other investigators have
found gradually increased metabolite excretion suggestive of
bioaccumulation of metabolites.
-------
~38-
Toxicity
The principal toxic effect of concern with TCE is carcinogenicity,
TCE was shown to be carcinogenic in mice via inhalatio~ exposure in
three sets of reported results, although two of these studies were
faulty.
As of the publication date of EPA's health assessment
document on TCE, inhalation cancer bioassays had not yielded
positive results with rats or hamsters.
In two oral studies
conducted by NTP and NCI, on the other hand, an increased incidence
of hepatocellar carcinoma was found in mice. Carcinogenic potency
factors of 6XIO-3(mg/kg/day)-1 for inhalation and 1.9x10-2
(mg/kg/day)-1 based on oral ingestion were computed by Fukada et.
ale (1983) and EPA respectively.
Although human epidemiological studies have failed to demonstrate a
relationship between increased cancer risk and TCE exposure, EPA has
applied proposed CAG criteria in evaluating overall animal evidence,
and has classified TCE as a Group B2-Probable Human Carcinogen.
Human overexposure to TCE produces depression of the central nervous
system.
Mental confusion, incoordination and insomnia have been
reported. The ACGIH (1983) recommended a TWA-TLV of 50 ppm (270
mg/m3) and a STEL of 150 ppm (560 mg/mJ) for TCE.
TCE has been found to cause increased mutagenesis in several tests
uSing Salmonella tVPhinaurium and Saccharomyced cerev~ after
metabolic activation and in a mouse spot test conducted by Fahrig
(1977).
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-39-
Toxic effects of TCE have been demonstrated in humans and
experimental animals.
Results of subchronic oral exposure in
-
animals include increased liver weight ratio and elevated urine
ketone and protein levels in male rats at moderate doses and
decreased body weights, increased liver and kidney weights, and
elevated urine ketone and protein levels in both sexes of rats at
high doses.
In subchronic inhalation studies with rats and guinea
pigs, guinea pigs were found to be more sensitive than rats,
demonstrating decreased body weight at half the dosages inducing
similar effects in rats.
Acute responses of animals to TCE reported include increased liver
and kidney weight and cell changes in the cerebellum.
TCE
fatalities investigated have been reported to result from cardiac
arrhythmia caused by the potentiation of endogenous epinephrene by
TCE.
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-40-
1,2-Dichloroethylene
This toxicity profile will present a summary of available
toxicological information on both isomers of dichloroethylene,
trans-1,2-dichloroethylene and cis-1,2-dichloroethylene.
Very
little empirical data exists on either of th~ isomers.
Molecular
weight is 96.95.
Chemistry and Metabolism
Although pertinent data regarding oral absorption of DCEs is
unavailable, EPA (1980a) estimated that "virtually 100\ of ingested
DCE may be absorbed systemically," based on experimental studies by
Daniel (1963) and Monster (1976) using trichloroethylene.
Data regarding absorption via inhalation are similarly unavailable,
but the Daniel and Monster studies formed the basis for an EPA
estimate of 35 to 50 percent absorption (EPA, 1980a).
DCE metabolism has not been investigated.
Toxicity
Very little experimental investigation has addressed DCE's toxicity
to laboratory animals or humans.
Similarly, both isomers of 1,2-DCE
are designated as Group D-Unclassified by EPA's Cancer Assessment
Group.
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-41-
Limited data on subchronic exposure data on the trans isomer were
found.
An oral study with a mixture of isomers by Springer (1965)
and an inhalation study by Torkelson (unpublished, 1965) reported no
adverse effects.
Freundt et ale (1977) found progressive damage to
the lungs and fatty changes in the livers of Wistar rats
administered t-l,2,-DCE via inhalation.
Cis-l,2-DCE administered to rats by Jenkins et ale (1972) in a
single oral dose resulted in increased levels of a series of hepatic
enzymes indicative of hepat~toxicity.
The authors suggested that
the cis isomer was less hepatotoxic than l,l-DCE, but more
hepatotoxic than the trans isomer.
Freundt et ale (1977) exposed rats via inhalation to 200 ppm cis
isomer, finding inhibition of the mixed function oxidase system as
measured by several parameters, and suggested that the cis isomer
was a more potent inhibitor than the trans isomer in a later study
(Freundt and Macholz, 1978).
Similarly, EPA (1984) postulates that
the cis isomer might be expected to effect the toxicity of other
compounds metabolized via the mixed function oxidase system, due to
the effects of cis-l,2-DCE on cytochrome P-450.
Subsequent research
into toxic actions of metabolites (Costa and Ivanetich, 1982)
indicates that the cis isomer is probably nephrotoxic by analogy to
1,1-DCE (U.S. EPA, 1980b).
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.
,
-42-
Data on acute toxic effects of the DCE isomers are extremely
limited.
The Merck Index (1983) reports research indicating animal
liver and kidney injury and an LD50 (isomer unspecified) in rats of
770 mg/kg orally (RTECS, v.l, R.J. Lewis and R.L. Tatken, Eds.,
1979), while Sax (1983) reports lethal doses of 65,000 mg/m3/2 hrs
and 20,000 mg/m3/6 hrs administered to mice and cats respectively.
Sax reports a low toxic threshold via oral routes, stating that high
concentrations cause irritation and narcosis (species unspecified).
No data is available on the teratogenicity or carcinogenicity of
either DCE isomer.
The ACGIH (1980, 1983) established a TLV for
both isomers of 200 ppm (approximately 1000 mg/m3) based on
Torkelsen's unpublished 1965 study of sub-chronic inhalation
effects.
Research on the mutagenicity of the DCE isomers has been limited and
has produced mixed results.
Greion et ale (1975) found both cis and
trans isomers to be nonmutagenic to E.coli K12.
Cerna and Kypenova
(1977) tested both isomers with Salmonella tester strains using the
spot test.
In the same study, the trans isomer failed to induce
chromosomal aberrations in mouse bone marrow cells following
injections, but the cis isomer did produce dose-dependent increases
in mutations using the host-media bioassay.
The cis isomer also
induced chromosomal aberrations in the bone marrow cells of mice
given repeated injections.
The cis isomer failed to induce mutation
or gene conversion in Saccharomyces cerevesiae (Galli et al., 1982).
-------
APPENDIX 8
SlItMARy
ESTIMATED OOS'ffi CF Rf)tEDIAL ALTERNATIVES
Capital Costs
($)
O&M Costs
~
Present W:>rth
0&" Costs
($)
Present W:>rth
Total Costs
($)
Al ternati ve
II - Existing
Stripper
138,50UO)
9,870(E)
13l,607(A)
288,691(8)
111/ - Existing Stripper 302,41~D) 37,336(E) 229,403(C) 531,815
IV with Plume Treat-
nent and Injec-
tion (East or West)
I
~
V - Existing Stripper, 293,067(0) 43,124(E) 264,953(C) 558,020 w
Plune Treabnent
and Discharge to
Well Field
Notes:
(A)
A
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. .
-44-
'Apcendix C
Estimated Costs - Selected Alternative
ALTER~ATIVE III - Existing Air Stripper, Groundwater Collection,
Treatment and Injection East of the Plume
For the alternatives with remed1al action south of the River the
computer simulations indicate the contamination in the Well Field cOulo
re~ch 5 ppb in 10 years. Accordingly, the present worth calculations,
both for the on-Site stripping column and the off~Site remedial system are
assumed to have a useful life of 10 years for the economic evaluation.
A. Capital Costs - Off-Site Stripper
Subtotal
$ 28,000
32, 100
11,000
$ 71,100
1. Equipment
2. Labor
3. Other
4. Engineering (15~).
10,665
S. Contingencies (15~)
10,665
CAPITAL COST $ 92,410
$ 92,410
B. Capital Costs - Wells
1. 4 Extraction Wells
2. 6 Passive Injection Wells
Subtotal
S 28,553
26.449
S 55,002
<>
3. Engineering (15') S 8,250
4. Contingencies (15') 8,250
CAPITAL COST S 71,502 , ~ 71.~02
~Total Capital Cost of GW Treatment....$163,912
C. 0 & M Costs - Off Site Stripper
1. Power
2. Materials
3. Labor
TOTAL 0 & M
$ 4,600
S 1 ,400
, 9.600
S 15,600
S 15,600
D. 0 & M Costs - Wells
1.' Extraction Wells S 6,568
2. Passive Injection Wells J 5.300
TOTAL 0 & M S 11,868
°Total O&~ Cost of GW Treatme~i~.;...
S 11 ,868
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-45-
E. Capital Costs. ;xisting Stri1?per
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Column shell. internals and packing...............$
A 1 r b 1 owe r s. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Air Well/Foundation for building .................
Piping Valves and Appurtenances ..................
Air Duct work and Appurtenances..... .,.............
Ins t rurnent at; on. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical.......................................
Building and Site Work ...........................
Engineering (151)..................................$
40;775
4,620
12,875
7,500
7.260
1,320
14,700
21 ,800
16,630
Contingency (101 in this case because actual
costs figures are available).......................] 11,080
TOTAL CAPITAL COST $138.500
°Total Capital Cost of Existing Stripper...$l38,500(1)
F. Ope rat ion anci Maintenance (Annual) - I -.
1. Power..............................................$
2. . Materials..........................................
3. Labor................................... ...........
TOTAL O&M
°Tocal O&M Cost of Existing Stripper....
3.430
200
6.240
$ !:I.870
$' 9,870 (0)
Notes:
1. Existing Stripper is already built & paid for.
-------
RESPO~SIVE~ESS SU~~~RY
o
~
-------
".
-46-
Brewster Responsiveness Summary
To Comments At Public Meeting 8/21/86
C- One commenter asked if it was possible that the contamination
existed before 1978 and how the contamination was discovered
in 1978.
R- It is possible that the
groundwater before 1978
water supply until 1978
sampling.
C- The same commenter asked why it took from 1978 to 1985 to do
the Superfund study.
contamination existed in the spil and
but no contamination was found in the
when it was discovered in routine
R- Since the contamination was first discovered in 1978 several
measures were taken to protect the public health. These
measures included the investigation and use of alternate water
supplies, public health advisories to boil water when it was
necessary, and ultimately the construction of the packed
column air stripping system that is now successfully being
utilized. Superfund legislation was not enacted until 1980
and it was not until 1983 that Brewster was added to the
National Priorities List of Superfund sites.
C- One commenter asked what soil contamination has been found.
R- Semi-quantitative soil screening was conducted during soil
boring operations of the Remedial Investigation and the results
are included in the Remedial Investigation report. Heavy
contaminant concentrations have been found at depths of 30
feet and more at some locations.
C- Another commenter asked whether PCE was used in other than dry
cleaning operations.
R- PCE is also used for metal degreasing.
C- One commenter asked where other contaminants such as benzene
and xylene may have come from.
R- Benzene and xylene are found in gasoline which may have come
from a spill.
C- Another commenter asked what the source of the vinyl chloride
found might have been.
R- Vinyl chloride may have been generated as the result of the
biological degradation of PCE.
C- One commenter asked how it is possible to pinpoint the location
of the contaminant source or sources.
R- Historical studies of the area and business inventories could
help to identify possible sources. Site investigation, sampling
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-47~
C- One commenter asked whether the Alternate 2 packed column
would continue to work as the highly concentrated contaminant
plume is drawn toward the well field.
R- Any contamination from the pluMe will be diluted with su~round-
ing groundwater as it is drawn toward the well field. And by
holding on to contaminants the soil itself mitigates contaMinant
movement to a degree. Additionally, the packed tower has
flexibility and can react to higher concentrations; although
we believe conditions have reached steady state.
C- Two commenters asked if the system was reviewed periodically
and how often samples were taken.
R- Samples are taken and reviewed monthly as an indicator of the
system's operation. The historical trend, against which the
samples are reviewed is a good indication of concentration
levels and abrupt system adjustments and more frequent sampling
aren't considered necessary.
C- One commenter asked for clarification of the remediation
proposed south of the river and its cost.
R- The remediation proposed south of the river consists of
groundwater extraction via wells, pack column treatment, and
reinjection via wells. This would enable clean-up of TCE
to proposed Federal standards (Sppb) at both the well field
and the area south of the river in 10 years. Without this
remediation clean-up would take 25-30 years at the well field
and 30-35 years south of the river. The cost of this remedia-
tion would be the costs of ~lternate 3 Minus Alternate 2 or
5243,000.
C- One commenter wanted to know when a final decision would be made.
R- A final decision will be made after the public comment period
ends on September 8, 1986 via a Record of Decision which will
be issued by EPA.
C- One commenter asked if the Brewster contamination could be
affecting other water supply systems.
Q
~
u
R- There is no evidence of this and this is not suspected. The
Putnam County Department of Health would advise affected
communities if there were.
G
C- One commenter asked if there were any discharge to the river
and concern was expressed over fish uptake.
R- Very low concentrations (4ppb) were recorded at several points
along the river and continued monitoring is recommended at
those locations. The river itself though, has a natural
stripping action. At these low levels fish uptake is not a
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-48-
C- One commenter asked if any monitoring was done in the vicinity
of the Bottge septage site.
R- This storage area rests on fill directly over bedrock and any
contamination from this site would affect the bedrock aquifer.
however, the Brewster contamination exists primarily in the
unconsolidated aquifer and apparently is unrelated to the site.
The nature and quantity of substances used at this site also
make it an unlikely source. Therefore, no monitoring was
done.
C- One comrnenter asked what the likely sources of gasoline were.
R- The most likely source was a spill.
C- One commenter asked if VHO's could be assimilated other than
by direct ingestion.
R- VHO's can also be assimilated by inhalation and dermal contact.
C- Another commenter wanted to know what levels can now be found
in the village's drinking water.
R- The most recent sampling showed less than detectable levels
of VHOs (less than lppb).
C- Another commenter asked how long it would take for any
contamination to travel from Alben Cleaners to reach the well
field.
R- Groundwater would take approximately 6 years to travel this
route. Contaminant travel would take somewhat longer because
of the mitigating effects of the soil.
C- One commenter wanted to know if it was possible to estimate
the quantity of contaminants in the groundwater.
R- Not accurately, but we could estimate the amount which has
been stripped out to date, based on flow and removal percentages.
C- Another commenter asked if anything was being done to avoid
this type of contamination in the future.
R- At the Federal level legislation and regulation such as the
Resource Conservation and Recovery Act requires hazardous
substances to be monitored from cradle to grave. Various
other Federal and State programs require permits to transport,
-------
q
-49-
c- Another commenter asked if there were going to be any more
public meetings.
R~ No further public meetings will be held on the first operable
unit (consisting of continued operation of the existing on-Site
air stripper and construction of a groundwater management
system of extraction wells, treatment of extract groundwater,
and reinjection, to contain the plume of cQntamination and
restore groundwater quality south of the River). However
written comments can be submitted until September 8, 1986.
In the future an additional public meeting will be held on the
second operable unit which will address source control measures.
C- A final commenter asked if an endangerment assessment was done.
R- A risk assessment was conducted and the results are presented
in the Feasibility Study report.
~
~
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