United States
Environmental Protection
Agency
Office of
Emergency and
Remedial Response
EPA/ROD/R02-87/047
September 1987
$EPA Superfund
Record of Decision:
Katonah Municipal Well, NY
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TECHNICAL REPORT DATA
/Please read Instructions on ine reverse before completing)
4
1. REPORT NO.
EPA/ROD/R02-87/047
I. RECIPIENT'S ACCESSION NO.
!. TITLE AND SUBTITLE
UPERFUND RECORD OF DECISION
Katonah Municipal Well, NY
First Remedial Action - Final
S. REPORT DATE
September 25, 1987
A. PERFORMING ORGANIZATION CODE
7. AUTHOR'S)
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME ANO AOORESS
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME ANO ADDRESS
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
19. SUPPLEMENTARY NOTES
10. ABSTRACT
The Katonah Municipal Well site is located in the Village of Katonah in the Town of
Bedford, Westchester County, New York. The well is situated on a peninsula owned by the
City of New York that extends into the Muscoot Reservoir. In 1978 the Westchester •
County Department of Health (WCDH), acting on Putnam County Health Department findings,
;ampled the Katonah well and other local wells for contamination. These samples
levealed the presence of tetrachloroethylene (PCE) and other VOCs in the well water.
hese contaminants were traced to a local septic waste collector who was disposing of
wastes taken from several Katonah dry cleaning establishments. In 1978 the Katonah well
was closed and source control measures were initiated requiring dry cleaning
establishments to pump out their septic systems and modify solvent disposal techniques.
Initial attempts by WCDH and the Town of Bedford to remove contamination from the
affected aquifer failed. The primary contaminant of concern affecting the ground water
is PCE.
The selected remedial action for this site includes: installation of a new
production well adjacent to the abandoned well; filling and sealing of the abandoned
Katonah well; installation and operation of an onsite air stripping facility to remove
PCE and other volatiles from the aquifer with discharge of treated water to the Bedford
Consolidated Water District distributor system; establishment of a monitoring program to
(See Attached Sheet)
17.
KEY WORDS ANO DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATi Field/Croup
Record of Decision
Katonah Municipal Well, NY
First Remedial Action - Final
Contaminated Media: gw
Key contaminants: PCE, TCE
^^•oil
ISTRI8UTION STATEMENT
19. SECURITY
iS { Thil Report I
21. NO. OF PAG{
20. SECURITY CLASS /Tliii page/
None
22. PRICE
CPA Form 2220-1 (IUv. 4-77) PMCVIOUS COITION is
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EPA/ROD/R02-87/047
Katonah Municipal Well, NY
First Remedial Action - Final
16. ABSTRACT (continued)
detect residual contamination of treated water; and recommendations to the Town of
Bedford to remove trash and debris located on the peninsula. The estimated capital cost_
for this remedial action is £l,365,000 with annual O&M of $296,000.
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New York State Department Oi Environmental Conservation
50 Wolf Road, Albany, New York 12233-
Thomas C. Jorling
Commissioner
1987
Mr. Stephen Luftig
Acting Director
Office of Emergency and Remedial Response
U. S. Environmental Protection Agency
Region II
26 Federal Plaza
New York. NY 10278
.
Dear flr. lirfTg:
Re: Katonah Municipal Well Superfund
Site Remedial Action
The New York State Department of Environmental Conservation has
reviewed the information presented in the Remedial Investigation (RI)
Report for the Katonah Municipal Well Site and concurs With United States
Environmental Protection Agency's selection (prior to the public comment
period) of the installation of a new production well, the installation
of an air stripper to remove volatile organic compounds, and initiation
of a long-term monitoring program as the preferred remediation alternative.
The basis for our concurrence for installation of a new production
well is that the existing well has lost much of its original capacity
and would have to be renovated to restore that capacity. Because doing
so would cost about the same as a new well and because restoration of
the original capacity cannot be assured, we agree that a new well is
preferable. Also, we agree that installation and operation of an air
stripper are desirable,-because the risk analysis projects a potential
cancer risk of 2 x 10 in untreated well water under pumping conditions
(i.e., not static conditions) which is due primarily to tetrachloroethylene
(PCE). The stripping of PCE by a packed column, as proposed in the
preferred remediation alternative, would virtually eliminate PCE (and
any trichloroethylene in the raw water) from the water sent to the
distribution system and decrease the cancer risk to about 1 x 10" . A
long-term monitoring plan would complement this program by assuring that
this remediation measure provides acceptable water to the distribution
system.
Although we concur with the preferred alternative at this time, we
are interested in public comments that are made on this alternative as
well as on other alternatives, that were evaluated dliring the study. A
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Mr. Stephen Luftig Page 2
final remediation selection should only be made after carefully considering
al1 such coranents.
If you have questions, please call either me at (518) 457-6603 or
Bill Eberle, of my staff, at (518) 457-1708.
Sinerely,
./Norman H. Nosenchuck, P.E.
Director
Division of Solid and Hazardous Waste
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XAICNAH MUNICIPAL HELL SITE
BEDFCRD, NEK YCRK
FINAL RESPONSIVENESS SUMMARY
The U.S. Environmental Protection Agency (EPA) released the draft Remedial
Investigation and Feasibility Study (RI/FS) and Proposed Remedial Action Plan
(PRAP) for the Katonah Municipal Well site en July 22, 1987. 'Copies were
placed on file at the Katonah Village Library, Katonah, New York and the
Bedford Hills Free Library, Bedford Hills, New York for a three week public
conraent period from July 27, 1987 to August 20, 1987.
EPA also held a public nesting on August 5, 1987 at the Bedford Town Hall,
Bedford, New York to describe the proposed remedial alternatives and present
EPA's preferred remedial alternative for the Katcnah Municipal Well site.
A responsiveness summary is required by Superfund policy for the purpose of
providing EPA and the public with a surmary of citizen comments and con
about the site, and EPA's responses to those concerns. A sunmary of cements
received during the public ccrment period is provided in Section HI. All of
the Garments summarized in this document will be factored into EPA's final
decision of the preferred alternative for cleanup of the Katonah Municipal
Well.
This ccrmunity relations responsiveness summary for the Katonah Municipal Well
site is divided into the following sections:
I. Responsiveness Smeary Overview. This section briefly outlines the
proposed remedial alternatives as presented in EPA's draft FS, including
the preferred alternative.
U. Background on CrrrtnTni'ty Involvement and CLumans. This section provides
a brief history of community interest in the Katonah Municipal Well site
and a chronology of contunity relations activities conducted by EPA
during remedial activities.
HI. Summary of Ka-jor Questions and Oonments Received During the Public
fVrripiit Period and EPA P'-'HMgaes to ni'n*-a|tg. This section summarizes
raj or questions and Garments made verbally and in writing to EPA during
the public meeting and public comment period, and provides EPA responses
to these canments.
IV. Ppjmim'no; Concerns. This section dj'saissps caiuiiunity concerns about the
RI/FS that were not directly addressed during the RI/FS and that EPA
should consider in planning for, and conducting the remedial design and
remedial action for the Katonah Municipal Well site.
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I. EESKJCIVENESS SO-WARY
The Katonah Municipal Well Site is located in the Village of Xatonah in the
Town of Bedford in northeastern Westchester County, New York. During the Fall
of 1978, the Westchester County Department of Health (WCDH) surveyed drinking
water wells in Annonk, Mount Kisco, Bedford, and Katonah, following 'the
discovery of contaminants in the well supplying drinking water to the City of
Brewster, New York. Initial efforts to identify and characterize the
contaminants were a joint effort between WCDH and the New York State
C^oarbnent of Environmental Conservation (NYSDEC) . NYSDBC traced the
contamination detected in Uv3 Brewster well to the disposal site of a septic
waste hauler. NYSDEC discovered that the waste hauler had also collected
septic wastes containing volatile organic conpounds (VOCs) from a location in
Katonah. Pasprl on this discovery, NYSDEC officials then decided to
investigate the possibility of similar contamination in Katonah. NYSDEC' s
investigation revealed the presence of contaminants in samples taken from the
Katonah well. Subsequently, the Katonah Municipal Well was closed in Dgcgmher
1978 and has been out of service since that time except for brief periods in
1979, 1981, 1985, and 1987 when water samples were collected for analysis.
The Katonah Municipal Well is an EPA fund lead site and was included on the
National Priority List (NFL) of Super-fund sites in October 1984. Following
placement of the Katonah Municipal Well on the NFL, EPA assumed responsibility
for clean-up of site contamination. In June of 1985, EPA began the RI/FS of
the Katonah Municipal Well. The objectives of the RI/FS were to determine the
nature and extent of contamination affecting the Katonah Municipal Well, and
to evaluate potential cleanup remedies. The RI/FS was conducted in two
phases. The need for a phased approach resulted fran extensive data gaps in
areas such as hydrogeology and source characterization. Both phases of the
RI/FS were corpleted in June 1987.
Results of the RI indicated that the primary contaminants of concern at the
site included tetrachloroethylene (PCE) , trichloroethylene (TCE) , and metals
such as lead, nickel, and zinc.
The draft RI/FS describes several remedial alternatives that are judged by EPA
to be the most effective for dealing with site contamination. These are
briefly sumnarized below.
Al+^rnative l; No Action.
Under the no-action alternative, the site would remain in its present
condition with no reduction of contamination or risk. However, the well would
remain closed and the primary risk via ingestion of contaminated groundwater
would be eliminated.
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rineraticn
Alternatives 2 and 3 involve excavation of contaminated soils beneath the
pumphouse. The only distinction between alternatives 2 and 3 is the. method of
disposal. The first method considers disposal off -site in a secured landfill.
Alternative 3 considers destruction of contaminants through off-site soil
incineration. This method involves significantly higher costs but would
satisfy the intent of the Superfund Amendments and Reauthorization Act
favoring permanent solutions.
4?
of
Alternative 4 addresses containment of contaminated soil and groundwater., It
includes the installation of four purge wells that would be placed upgradient
from the peninsula, upon which the Katonah Well is situated. These wells. .
would be used to extract contaminated groundwater, which would then be treated
to remove both inorganic and organic corpounds that may exceed drinking water
standards. The treatment system would employ air stripping, granular
activated carbon and chemical precipitation. The first two methods are for
removal of organic compounds detected in area groundwater and the latter
removes metals that were detected in sane monitoring wells at high levels.
nt of the lost Water Resource vith No Site
Alternative 5 provides for the installation of a new well in an area of town
unaffected by contamination. This well would then be connected to the
existing distribution system. Soil and groundwater in the vicinity of the
existing Katonah Well would not be remediated.
Alternative 6 involves installation of' a new well near the Katonah Well and
on-site treatment of water from the new well with an air stripper. This
treatment system would remove the contaminants detected in the Katonah Well to
levels above drinking water standards.
and On-Site Treatrynt with an
Alternative 7 includes renovation of the existing Katonah Well and on-site
treatment of well water with an air stripper.
All of the alternatives discussed above, except for the no-action alternative,
include a comprehensive groundwater monitoring program, designed to ensure a
safe drinking water source for the community.
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Technologies utilized in the above-listed alternatives include:
Bocavation: the physical removal of contaminated soils. These soils may
then be disposed at an approved off-site landfill facility, or off-site
incinerator.
Ocntairinent: the extraction of groundwater from the well, the removal of
top soil, and placement of a synthetic liner in the excavated area with
clean fill used to replace the removed contaminated soil.
Replacement: the actual drilling of a new well in another location.
Renovation: restoration of the existing well to the most efficient
conditions utilizing various treatments or reconstruction methods. •
"Air stripping: this involves passing air through a column with a
counterflow of contaminated water to cause volatilization of volatile
organic unrounds in the contaminated water.
After careful evaluation of the remedial alternatives, EPA has selected
Alternative 6: Installation of a New Well and On-Site Treatment with an Air
Stripper as the preferred remedial alternative for the Katonah Well Site.
This alternative involves the installation of a .new production well facility
near the present Katonah well, and on-site treatment of water from the new
well with an air stripper. This treatment system would remove the
contaminants detected in the Katonah well to levels which exceed minimum
health and safety standards established for drinking water.
H. BACHSROCND CN OM-tNTIY INVOLVEMENT AND CCNCBVS
Community concern regarding the Katonah Municipal Well site has been extremely
low, and has diminished since the closing of the well and development of an
alternate water supply in 1978. The perception among residents is that this
alternate water supply has substantially mitigated the problem at the Katonah
Municipal Well. However, in April 1986, when EPA conducted on-site interviews
in the Katonah immunity, the following specific areas of concern were
identified by local officials and the site community.
rhysical and Financial Impact on Katcnah's QuiiHmial Center. Due to the
proximity of the well to Katonah 's central business district, local officials
have expressed concern over the potential impact that site work may have on
parking, commuter and traffic patterns, and resultant effects on local
businesses.
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Relationship of the Katonah Well to the Current Municipal Water Supply.
Village officials are concerned that activity at the Katonah Well Site nay
generate renewed interest fron residents regarding the town's current source
of drinking water. Concern focuses on the perception that residents may
question the quality of the current municipal water supply if they perceive a
link with the Katonah Wen.
Federal, State, and County Juriadictional Issues. Local citizen leaders have
expressed a degree of confusion regarding roles and responsibilities of the
different levels of government involved in the sampling and monitoring of
private residential wells in Bedford Village.
During EPA's remedial site activities, several site-specific cccounity
relations activities have occurred as part of EPA's overall site community
relations program. These activities are briefly summarized below.
A fact sheet was developed and sent to community members in April 1986,
prior to the initiation of the RI/FS. The purpose of this fact sheet was
to provide interested residents with information on site background;
nature of the contamination problem at the Katonah Municipal Well site;
EPA's site investigation activities; plans for future EPA site
activities, and the Superfund process in general.
In April 1986, EPA conducted on-site interviews, and, as a result,
developed a site-specific community relations plan for conducting
omtitinity relations activities at the site throughout the RI/FS.
A field information handout, which explained the purpose of the RI/FS at
the Katonah Well, and announced public availability sessions, was
developed by EPA and distributed to interested citizens. EPA held a
public briefing in April 1986 to explain the purpose of the PI/PS.
Approximately 15 people attended this public briefing. Following this
briefing, EPA conducted two public availability sessions.
In December 1986, EPA and it's contractor personnel, met with
representatives from the New York State Department of Environmental
Conservation (NYSDBC); the New York City Department of Environmental
Protection (NYCDEP); the Westchester County Department of Health (WCDH),
and local officials from the Town of Bedford. The purpose of this
meeting was to present the results of Phase I of the RI, and to discuss
proposed site activities for Phase H.
On July 29, 1987, a public notice announcing the public comment period
and upcoming public meeting, was published in the White Plains, New York,
Reporter Dispatch. EPA developed and distributed an additional fact
sheet, which outlined the remedial alternatives and identified EPA's
preferred remedial alternative. EPA held a public meeting on August 5,
1987 to provide information on EPA's preferred remedial alternative, the
proposed remedial action plan, and to answer any'questions pertaining to
the site. local officials representing the community attended the public
meeting on the RI/FS.
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HI. SCM-ftRY OF MAJOR CPESTTONS AND OJfffiNTS RECEIVED DURING TEE FOBLTC
CDM-IENT PERIOD AND EPA's RESPONSES TO CQ>WENI5.
A public Garment period was held from July 27, 1987 through August 20, 1987 to
receive comments from the public en the draft TS and EPA's preferred remedial
alternative for the Katonah Municipal Well site. The public mating for the
Katonah Municipal Well site vas held on August 5, 1987 at 7:00 p.m. at the
Bedford Hills Town Kail, Bedford Hills, New York. The meeting, was attended
by four EPA officials, three members of EPA's contractor staff, and four local
officials. The purpose of the meeting was to present and rfDenies the draft FS
for the Katonah Well site, to apprise local officials and interested residents
of the agency's preferred alternative for remediation of the site
contamination, and to provide an opportunity for interested parties to present
oral cements and questions to EPA. These comments are recorded in a
transcript of the meeting which is available for review at EPA's regional
office in New York City and the information repositories located in Bedford
Hills and Katonah. Cements received during the comment period are
categorized below by topic:
A. Liability of potentially responsible parties; (FRP's) and
apportionment of liability.
B. Origin, nature, and extent of contaminants, and
C. Other
A. T.T&RT f.Tiv OF POTENTIALLY RESPCKSIRLR PARTIES
1. CO-KENT: A local official requested information regarding the Town of
Bedford being named as a PRP and asked who would conduct negotiations
arning determination of liability.
EPA KhiiKKiK: liability determination would be up to town attorneys and
the EPA Region II legal staff. EPA will notify the town of how the
agency wishes to proceed with legal issues, and indicate whether the
agency feels there is any liability on the part of the town.
2. CO-WENT: A local official expressed concern that the town would be
required to legally pursue a PRP and implement a remedial action if no
legal action was taken by EPA, and wanted information on how financial
liability would be apportioned if multiple PRPs are identified.
EPA Kh£K*&K: EPA has already notified a potential PRP other than the
town. If the town were to conduct and implement the remedial design,
implementation of a remedial action would be aocarplished through an
administrative order. If this order was signed with EPA, the town would
then have legal authority, and the power to exercise that authority, in
pursuit of a PRP. EPA would aid the town in providing technical
expertise, and determination of degree of PRP liability. It is difficult
to determine apportionment of liability. However, if the town were to
sign such an order, the legal pursuit of additional PRPs would then
become an option that the town may wish to consider. Upon further
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discussion with EPA's legal staff, it has been determined that the
ability of the town to pursue legal action regarding additional PRPs
would remain intact.
3. GO-MENI: A local official inquired as to EPA's availability for possible
court appearances regarding determination of a PRP.
EPA RESPONSE: A comprehensive administrative record, which incorporates
all data utilized in formulating a decision for this site, would be
available for use in any litigation. That is the purpose of this
administrative record.
4. COWEOT: A local official askpd whether there would be any legal
briefing before signing of an administrative order.
EPA RESPONSE: Any legal discussions would be conducted by EPA attorneys.
Upon the signing of an administrative order by the town, EPA's direct
involvement would <*•?«* n<«h and the town would assume primary
responsibility from that point regarding legal action against any
additional FRPs. EPA's legal staff would not be involved with any
decisions made by the town regarding a FRP.
5. OJMEOT: An official inquired as to what assistance EPA would provide to
the town regarding its role in the signing of an administrative order.
EPA RESPONSE: Assistance regarding the signing of an administrative
order and definition of the town's role in the order would be provided by
EPA enforcement personnel and legal staff.
6. GCM4EHT: A local official expressed concern over procedures regarding
apportionment of funding among multiple PRPs.
EPA RESPONSE: There is a provision in the Super fund law dealing with
mixed funding among itultiple PRPs. This is a relatively new provision
and this issue should be dealt with by EPA's legal staff. If all PRPs
were contacted, EPA would assist the town in liability apportionment.
However, if these PRPs did not voluntarily assume liability, the agency
is not in a position to carpel a PRP to assume this liability. The
rationale behind pursuit of a PRP is to recover costs incurred by EPA in
conducting studies related to a particular site. If a PRP is identified
and is financially unable to assume liability, it is unlikely that the
agency would legally pursue recovery of costs.
7. OGHffiNT: A local official inquired as to the scheduling of notifications
to PRPs.
EPA RESPONSE: Identified PRPs will be notified by the end of August
1987. The record of decision will be signed as scon as possible
following this notification.
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B. CRICHN, NMORE, AND EXTENT OF
1. COMMENT: A local official expressed concern over the type, amounts, and
location of detected contaminants. ~~ " .
EPA RESPONSE: PCE and TCE, vhich are used as industrial • solvents and
degreasers, were found at low levels near a local dry cleaning
establishment. These were also found at trace levels in a monitoring
well in the sane area. There were also low levels of these chemicals
detected in the soil at the level of the well pump. The highest
concentrations were detected in Well W-9, which is located directly in
front of the punphouse. PCE was detected at 36 parts per billion. In
contrast, a recognized acceptable level of PCE contamination is less than
5 parts per billion.
2. CO-WENT: A Town official inquired as to the amounts of •detected
contaminants which precipitated the closing of the well in 1978, and
whether it was standard practice to close a well baser! on these amounts.
EPA RESPONSE: Vfcen combined, the total contamination level «*xneflfV?d 100
parts per billion (ppb) , which is a sufficient amount to close the well.
The PCE level alone exceeded 50 ppb, which is, in itself, a high enough
level of contamination to warrant closing of the veil. PCBs were
detected in Well W-8 upon two separate sarrpling events. However, the
amount of PCBs detected was low, and not found in subsequent sampling.
PCS is insoluble and tends to cling to soil particles. It was unusual
that -PCEs were not detected in subsequent sanplirg.
3. COMMENT: A local official expressed concern over the origin of metals
contamination such as lead, nickel, and zinc, and whether the detection
of hydrocarbons *«***<1 to well contamination.
EPA KESPOEE: The origin of these contaminants has not been determined.
Lead is a conponent of gasoline and the town has demonstrated a record of
dunping street cleaning debris near the well. Hydrocarbons were not
detected in the well.
C. (JIHiH CONCERNS
1. COMMENT: A local official asked about the source of water caning into
the municipal well and whether PCE was detected below the level of the
water table.
EPA RESPCKSE: Approximately eighty percent of the well recharge water
comes from the reservoir. This is a number used in modelling efforts and
not intended to be exact. It does, however, establish a general
guideline to determine how much water is drawn from the reservoir to
replenish the well as well water is being used. PCE was detected in the
grcundwater in all sampling locations except for the pumphouse.
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IV. REKVINDC GCNCEKKS
This section describes additional cuiumnity concerns that- EPA should be aware
of in preparing to undertake the remedial design and remedial action at the
Katonah Mmicipal Well site. . -••'.»
Roles and Responsibilities of PRPs. Concern has been expressed regarding
the roles and responsibilities of any identified PRPs. Concern focuses
on the apportionment of liability among multiple PRPs, if and when
identified, and what responsibilities the town nay incur following PRP
identification.
Enforcement Actions. Local officials should be kept informed as to the
progress of any enforcement action taken by the agency.
• .Site Activity DTring the Remedial Dp^ign/Rgrnedial Action Ryi?*. Future
remedial design activities nay generate renewed interest in the Katonah
Municipal Well problem. The comunity should be informed as to the
schedule, type, and duration of these activities to ensure that expressed
ems by residents and local officials continue to be addressed.
In addition, the three comunity relations Isretps identified in the corawnity
relaticrs plan for this site, and described on pages 4 and 5 of this
responsiveness sunmary will continue to be issues that EPA should be aware of
throughout remedial design activities.
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DECLARATION FOR THE RECORD OF DECISION
SITE NAME AND LOCATION
Katonah Municipal Well, Town of Bedford, Westchester County,
New York
STATEMENT OF PURPOSE
This decision document represents the selected remedial action
for the Katonah Municipal Well site, developed in accordance with
the Comprehensive Environmental Response, Compensation, and
Liability Act of 1980, 42 USC §9601, et seq., 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,
November 20, 1985.
STATEMENT OF BASIS
This decision is based on the administrative record for the
Katonah Municipal Well site. A copy of the record is available
for review at the information repository for the site and at
the regional office. The following documents, which are part
of the administrative record, were primarily relied upon in
making this decision:
- Draft Remedial Investigation Report, Katonah Municipal Well
Site, prepared by Camp Dresser and McKee, Inc., July 1987
- Draft Feasibility Study Report, Katonah Municipal Well
Site, prepared by Camp Dresser and McKee, Inc., July 1987
- Proposed Remedial Action Plan, Katonah Municipal Well Site,
July 1987
- The attached Summary of Remedial Alternative Selection for
the Katonah Municipal Well site
- The attached Responsiveness Summary for the site, which
incorporates any public comments received
- Staff summaries and recommendations
DESCRIPTION OF SELECTED REMEDY
This Record of Decision (ROD) for the Katonah Municipal Well site
calls for the following actions, which address public water supply
and aquifer remediation.
o A new production well will be installed on the peninsula owned
by the City of New York, designed for a rated capacity of 370
gallons per minute (gpm). The existing Katonah well will
be filled and sealed to mitigate the possibility of contaminants
entering the aquifer by natural or other means and to
prevent future use of untreated ground water.
o A new water treatment facility will be installed on the
peninsula, designed to treat the rated capacity of the
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production well. Treatment processes will include an air
stripper and disinfection. Treated water will be discharged
to the Bedford Consolidated Water District distribution
system/ to be used for drinking water by the community.
o A monitoring program designed to detect the presence of
identified contaminants in the treated water will be
required. The results of this monitoring program will be
evaluated on a routine basis to ensure protection of
human health.
o A general clean up of the peninsula area to remove trash and
debris, which may adversely affect water quality in the
future, is recommended for Town implementation. Also,
past practices of using the peninsula area as a convenient
dumping area for debris and other potentially hazardous
material should be discontinued.
DECLARATIONS
The selected remedy is protective of human health and the
environment, attains Federal and State requirements that are
applicable or relevant and appropriate and is cost effective.
This remedy satisfies the preference for treatment that reduces
the toxicity, mobility, or volume of hazardous substances,
pollutants or contaminants as a principal element. Finally,
it is determined that this remedy utilizes permanent solutions
and alternative treatment to the maximum extent practicable.
The action will require future operation and maintenance
activities to ensure the continued effectiveness of the remedy.
The start-up activities, which will ensure the operational
effectiveness of the design, will be considered part of the
approved remedial action and eligible for Superfund monies
for a period of up to one year. The remainder of the activities
are considered operation and maintenance and are therefore
the responsibility of New York State.
The State of New York has been consulted and agrees with the
approved remedy (see attached letter).
I have also determined that the action being taken will be
appropriate when balanced against the future availability of
Trust Fund monies for use at other sites.
if, tifl
Date ' Christopher J. Dadc/ett
Regional Administrator
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TABLE OF CONTENTS
PAGE
I. SITE LOCATION AND DESCRIPTION 1
II. SITE HISTORY 1
A. Current Site Status 2
B. Risk Assessment 2
Contaminants of Concern 3
Exposure Pathways . 4
Risk Characterization 4
Environmental Impacts 5
III. ENFORCEMENT ANALYSIS 5
IV. COMMUNITY RELATIONS 5
V. ALTERNATIVES EVALUATION 6
VI. SELECTED REMEDY 10
VII. FIGURES 13
VIII. TABLES . . '. 22
ATTACHMENTS
A - NYSDEC Letter of Concurrence
B - Responsiveness Summary
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FIGURES
FIGURE PAGE
1 - Site Location Map 13
2 - Site Layout Map 14
3 - Location of Stratographic Cross Sections 15
4 - Stratographic Cross Section A-A 16
5 - Stratographic Cross Section B-B 17
6 - Observed PCE Concentration in Katonah Well
During Pumping 18
7 - Ground Water Flow Without Pumping 19
8 - Ground Water Flow With Pumping 20
9 - Contaminated Flow Paths under Pumping and
Non Pumping Conditions 21
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TABLES
TABLE PAGE
1 - Cost Information for Remedial Alternatives 22
2 - Design Information for Selected Remedy 23
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-1-
I. SITE LOCATION AND DESCRIPTION
The Katonah Municipal Well site is located in the Village of
Katonah in the Town of Bedford, Westchester County, New York, on
land owned by the City of New York (NYC). (See Figure 1.) The
Katonah Well is situated on a peninsula that extends into the
Muscoot Reservoir, part of the Croton Reservoir system. (See
Figure 2.) The well was designed in the early part of this
century as an infiltration gallery, drawing water primarily
from the reservoir, with'some contribution from the aquifer
underlying the Village.
The Village of Katonah is moderately populated, with local zoning
policy allowing for less than one acre development. The village
is underlain by a glacial stratified drift aquifer, that receives
waste discharge from local septic systems. (See Figures 3 - 5".)
II. SITE HISTORY
During the fall of 1978, the Westchester County Department of
Health (WCDH) surveyed the water quality of municipal wells in
Armonk, Mount Kisco, Bedford and Katonah. This survey was
undertaken after the Putnam County Health Department discovered
contamination in the Brewster Wellfield. The contamination
was traced to the disposal facility of a local septic waste
collector by the New York State Department of Environmental
Conservation (NYSDEC). Further investigation revealed that
the operator of this facility had collected wastes from
septic systems of dry cleaners located in the Village of
Katonah. Samples from some of these septic systems .'revealed
the presence of tetrachloroethylene (PCE). The WCDH then
sampled the Katonah Well and detected the presence of several
halogenated organic compounds including, tetrachloroethylene,
dibromochloromethane, bromodichloromethane and bromoform.
The well was closed and the Town temporarily interconnected
with the Bedford Correctional Facility Water System to restore
water to the 6200 people dependent upon the Katonah Well for
over sixty percent of their supply.
Source control was implemented by the WCDH. in 1978. The dry
cleaners were required to pump out their septic systems and
modify their disposal techniques for waste solvents. Additional
source control measures were implemented by the Town of Bedford
through the promulgation of stringent aquifer protection
ordinances that regulate waste discharges to Town aquifers.
Initial attempts by the Town and the WCDH to remove the
contamination from the aquifer failed. These included pumping
the well to waste and raising the stage of the Muscoot Reservoir
to dilute the concentration of contaminants in the Katonah
Well by increasing the contribution of clean reservoir water.
The site was then referred to the NYSDEC for preliminary
assessment and site investigation. These efforts caused the
site to be proposed for the National Priorities List (NPL)
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-2-
in October 1984. NYSDEC entered into an agreement with-USEPA
and the site was designated for a Federal lead, remedial
investigation/feasibility study (RI/FS) to determine the nature
and extent of contamination and to develop long term remedial
alternatives to clean up the contamination. In June 1985, USEPA
procured the services of Camp Dresser and McKee Inc. to
perform the RI/FS.
A. Current Site Status
USEPA completed an RI/FS for the Katonah Municipal Well in July
1987. Contaminant sources, transport, receptors and potential
risks are evaluated in the reports documenting the results of
these studies. The following is a brief summary of the types
and concentrations of contaminants detected at the site.
A number of hazardous substances were detected in groundwater
monitoring wells, soil borings, and surface water and sediment
samples collected during the remedial investigation. For the
most part, their appearance was erratic between sampling events
and locations. Only tetrachloroethylene (PCE), the original
contaminant of concern, appeared somewhat consistently in
the sampling data collected during the Rl. Further, only PCE was
detected in the Katonah Well effluent at levels that exceed
standards established for the site.
There is currently no Federal or State standard for PCE. There
is a New York State Department of Health (NYSDOH) guideline value
of 50 ug/1 for any single volatile organic compound, a NYSDEC
Technical and Operational Guidance Series (TOGS) value of 0.7
ug/1, and a Federal Water Quality Criteria value of 0.8 ug/1.
The highest value of PCE found in groundwater during the RI was
36 ug/1, found in monitoring well W-9, located on the peninsula.
The highest value of PCE found in any soil sample was 81 ugAg/
found in soil boring B-3, located near a dry cleaners septic
system.
A four week pump test of the Katonah Well was performed to
delineate its hydrogeologic influence on local surface and ground
water and to characterize present effluent, water quality. PCE
was not detected in the well initially, however, the concentration
increased with time and leveled off at approximately 20 ug/1
after three weeks of pumping. This trend corresponded with the
results of a pump test carried out in 1981 by the WCDH. However,
at that time the concentration of PCE detected in the well's
discharge leveled off at approximately 75 ug/1. (See Figure 6.)
This significant decrease in concentration over time is
probably the result of natural attenuation and possibly some
biodegradation. It also indicates that aquifer restoration
may be possible over time and may be enhanced by pumping.
B. Risk Assessment
The primary potential human health impact at the Katonah site is
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-3-
through ingestion of contaminated groundwater. In order to
assess the level of risk associated with the contamination, a
risk assessment was conducted. This assessment provides
a quantitative estimate of risk levels under existing conditions,
in the absence of remedial action. This is used to determine
whether remedial action at the site is warranted. The risk
assessment was developed as follows: identify contaminants of
concern; describe pathways of exposure associated with site
contaminants; estimate levels of exposure and determine
populations affected; and characterize current and potential
risks to human health and the environment.
Contaminants of Concern
Two separate risk assessments were performed on chemicals
identified in the RI. The first utilized data from the Katonah
Well collected during the course of a four week pump test. The
second scenario evaluated risks from ingestion of ground water
containing concentrations of chemicals of concern that were
collected from monitoring wells under non-pumping conditions.
The excess cancer risk associated with groundwater use exceeded
10~6 under both scenarios. This means that one might expect
greater than one additional incidence of cancer in a hypothetical
population of 1,000,000 people resulting from ingestion of
contaminated ground water.
The first scenario focusing on analytical results from the numerous
sampling events conducted on effluent water from the Katonah Well
represents actual ground water ingestion data. The only
chemical of concern detected during any sampling event exceeding
the excess cancer risk level of 10~6 was tetrachloroethylene
(PCE). The associated excess cancer risk for ingestion of Katonah
Well water contaminated with PCE at a level of 20 ug/1 is
10~5. There was no statistical difference in the excess
cancer risk values obtained using maximum concentrations
versus those obtained using a geometric mean.
The second scenario incorporated data from the nine monitoring
wells installed during the RI. It was incorporated into the risk
assessment to represent the potential worst case scenario,
involving increased risk of cancer from ingestion of ground
water. This scenario attempts to simulate the conditions that
might exist if the reservoir stage were lowered, thereby
decreasing its contribution to the well and increasing the
percentage of water derived from area ground water. This
data was collected during static conditions and demonstrated
significant fluctuations between sampling events and locations.
Five organic compounds, along with arsenic, were identified
as contributing to excess cancer risk.
The five organic chemicals contributing to excess cancer risk
under the second scenario include benzene, bis(2-ethylhexyl)
phthalate, polychlorinated biphenyls, tetrachloroethylene, and
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-4-
trichloroethene. Benzene was detected during only one sampling
event at a level exceeding the MCL of 5 ug/1. Bis(2ethylhexyl)
phthalate is a common lab contaminant and was detected at levels
significantly lower than the guideline Federal Water Quality
Criteria value for human health of 15 mg/1. pCBs were detected
in only one monitoring well during one sampling.event. Also, the
monitoring well was installed in a borehole and corresponding
split spoon samples taken from this location failed to reveal the
presence of PCBs. PCBs are relatively insoluble in water,
tending to adsorb to soils. Thus, the presence of this chemical
is suspect.
Arsenic was the primary contaminant of concern driving the excess
cancer risk under the second scenario. However, its presence at
levels that correspond with an excess cancer risk greater than
10~6 in certain monitoring well locations during particular
sampling events can probably be attributed to a sampling
procedure not in accordance with standard methods for sampling
inorganics. Monitoring well samples for inorganics were not
filtered and were preserved by lowering the pH to 2, to
preserve metals. This procedure would release metals such as
arsenic from solids present in the sample that would not
normally be associated with ground water ingestion from a properly
developed production well. The monitoring program to be
established during the remedial design will verify this conclusion.
Exposure Pathways
Based upon the results of the endangerment assessment contained
in the Rl report, it has been determined that ingestion of
contaminated ground water poses the greatest human health risk at
the Katonah Municipal Well site. Ground water flows underneath
the Village of Katonah and discharges into the Muscoot Reservoir.
There are no residential wells in the flow path, other than the
Katonah Well. Local ordinance requires that all residences in
the vicinity tie into the municipal water supply system. The
only chemical detected in the Katonah Well at a level exceeding
standards established for the site is tetrachloroethylene (PCE).
Risk Characteristics
Available analytical data from the Katonah Well indicates that
there is an excess cancer risk of 10~5 associated with ingestion
of water from the Katonah Well. Monitoring well data indicates
that there is some potential carcinogenic risk associated with
four additional organic compounds and arsenic. However, the
data was erratic. Any risk derived from this data incorporates
this uncertainty and assumes that ground water of the quality
observed in some monitoring locations at particular times
will reach the Katonah Well and be ingested. To ensure a
continued safe drinking water supply for the community, as
part of the selected remedial alternative, a long term monitoring
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-5-
program will be proposed and will scan for identified site
contaminants.
Environmental Impacts
Potential environmental impacts from the contamination a'ffecting
the Katonah Well are limited in scope and degree. Low level,
ubiquitous contamination of the aquifer was revealed during the
RI. The only chemical that appeared consistently in sampling
results was PCE. The only potentially affected surface waters in
the area are the Katonah Brook and the Muscoot Reservoir. These
have been sampled since the discovery of contamination in the
Katonah Well and were resampled six times each during the Ri.
They have not been affected by the contamination and the
potential for future contamination is highly improbable.
III. ENFORCEMENT
General notice letters were sent to four dry cleaners and
three property owners on April 19/ 1985 identifying them as
Potentially Responsible Parties (PRPs) under Section 107 (a)
of CERCLA for the contamination at the Katonah Municipal Well
site. In their respective responses to our notice letters,
none of the PRPs expressed an interest in conducting the RI/FS.
EPA therefore funded the study in July 1985.
A special notice letter was sent to the Town of Bedford on
September 2, 1982, in addition to the PRPs who previously
received general notice. Sampling data confirmed statements
by the Foreman of the Bedford Consolidated Water District
that Town employees had dumped waste solvents down a drain
located in a pumphouse less than 100 feet from the Katonah
Well.
IV. COMMUNITY RELATIONS
Community involvement was solicited early in the RI/FS process at
the Katonah Municipal Well site. A public meeting was held on
April 23, 1986 to identify areas of community concern and to
provide an opportunity for public participation. Only Town
officials and a potentially responsible party attended. Another
public meeting was held August 5, 1987 to discuss the results
of the RI/FS and to present EPA's preferred remedial alternative.
Once again, attendance was limited to Town officials.
Bedford officials characterize the contamination at the Katonah
Well site as an old problem, long forgotten by most residents of
Bedford. Local officials have received few complaints or queries
regarding the site since the well was shut down in 1978. They
attribute this to the fact that the well was closed immediately
after contamination was discovered.
Specific concerns raised during the public comment period,
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-6-
including comments made at the public meeting held on August 5,
1987, at the Bedford Town Hall, are addressed in the attached
Responsiveness Summary. A transcript of the public meeting is
available in the Administrative Record, located..at the information
repository and the regional office.
V. ALTERNATIVES EVALUATION
The remedial alternatives for the Katonah Municipal Well site
were developed and evaluated using the Comprehensive
Environmental Response, Compensation, and Liability Act of 1980,
42 USC §9601, et seq., as amended by the Superfund Amendments
and Reauthorization Act of 1986, the National Oil and Hazardous
Substances Pollution Contingency Plan (NCP), 40 CFR Part 300,
and the "Guidance on Feasibility Studies Under CERCLA", as
guidance.
Seven remedial alternatives were presented in the FS by Camp
Dresser and McKee Inc., with five of these containing two
subcategories, generally distinguishing between methods of
disposal for excavated materials. USEPA issued a Proposed
Remedial Action Plan (PRAP) in July 1987 to solicit public
comment upon the agency's preferred alternative. The PRAP
restructured the remedial alternatives presented in the FS.
Excavation was broken out as a separate alternative and the
monitoring program was removed from the no action alternative.
In addition, capital costs were reduced to r fleet the
extraction of excavation as a separate alter, ative and the
removal of other items deemed unnecessary for the successful
implementation and cost effectiveness of the remedial
alternatives. Alternatives will henceforth be presented as
in the PRAP. All information regarding the alternatives
presented in the PRAP has been extracted from the FS and is
easily discernible.
The seven remedial alternatives'documented in the
PRAP, and their associated capital costs, operation and
maintenance present worth costs, and total present worth costs
are provided in Tab1 1.
Alternative 1; No Action
The no action alternative would leave the site in its present
condition with no reduction of contamination other than
through natural attenuation. However, the Katonah Well would
remain closed and the primary risk via ingestion of contaminated
groundwater would be eliminated. This alternative would result
in the loss of this aquifer system as a water resource for the
community. It would involve placing restrictions on water use in
the area and would not address aquifer restoration.
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-7-
Alternatives 2 and 3: Excavation of Soils and
Off Site Disposal
Alternatives 2 and 3, as delineated in the PRAP address removal
of contaminated peninsula soils by excavation. These
alternatives propose the removal of approximately 1000 cubic
yards of soil underneath the existing pumphouse. This possible
source of contamination to the Katonah Well was revealed by a
Town employee; Analytical results on soil samples from the
pumphouse drain revealed the presence of chloroform at 11,000
ug/kg and several other organic compounds at levels below
Contract Laboratory Program (CLP) detection limits in the upper
portion of the drain. A soil boring down this drain revealed the
presence of chloroform at 200 ugAg and chlordane at 440 ug/kg in
a split spoon sample taken from three to five feet below the .top
of the drain. Other organic compounds were detected in split
spoon samples from this borehole at levels below CLP established
detection limits.
Excavation materials in alternative 2 that are determined to be
hazardous would be disposed of in a RCRA approved facility.
However, implementation of this alternative without pretreatment
would probably be precluded by the Congressionally imposed
land ban date of November 1988. Alternative 3 would dispose
of contaminated soils by off site incineration, satisfying
the statutory prerogative favoring permanent remedies and use
of alternative treatment technologies to the maximum extent
practicable. However, excavation under either alternative is
not warranted given the low levels of contamination and the
results of a four week pump test conducted during the RI.
The organic compounds detected in the soil boring beneath the
pumphouse drain are present in low levels, except for chloroform.
They have not been detected in numerous ground water sampling
events at any location and were not detected at any time in
the Katonah Well during a four Week pump test conducted
during the RI or in the many historical sampling events
conducted on the well by the WCHD and others. Excavation of
this material would be a superfluous attempt at source control.
Source control measures were implemented by the WCDH in 1978.
Efforts were made by the County to work with the dry cleaners
to correct problems and remove the sources. Additional source
control measures would-not contribute to the protectiveness of
the remedial action.
In addition, conditions on the peninsula make these alternatives
technically impracticable. The peninsula extends into the
Muscoot Reservoir and the water table coincides with the
water surface of the reservoir. Thus, excavation of soils
will require construction of a coffer dam and continuous
dewatering of the pit via pumping. These conditions together
with sample results dispute the protectiveness, implementability,
and cost effectiveness of the proposed excavation alternatives.
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-8-
Alternative 4; Containment of Contaminated
Ground Water and Soil
Alternative 4 addresses containment of contaminated ground water
and soil. It includes the installation of five extraction wells
that would be placed upgradient from the peninsula, upon which
the Katonah Well is situated. These would be designed to
intercept contaminated ground water prior to discharge to" the
Muscoot Reservoir and would be treated for removal of organic and
inorganic constituents that may exceed drinking water standards.
The treated water would be discharged to the nearby Bedford
Consolidated Water District distribution system, to be used as
drinking water. The contaminated soil parcel proposed for
excavation in alternatives 2 and 3 would be contained through the
installation of a synthetic liner and clean cover material.
Containment of the contaminated soil parcel is considered
reliable and protective of human health. However, the hydraulic
containment of contaminated ground water is not considered to be
reliable or technically feasible at the Katonah site.
Containment of ground water via purge wells is susceptible to
operational and maintenance problems and is vulnerable to
extreme fluctuations in natural conditions, such as drought and
heavy rainfall, and variations in other relevant design
parameters such as changes in the reservoir stage and
interruptions in continuous pumping. Also, ground water
modeling conducted during the RI indicates that aquifer
restoration would not be significantly expedited by the
proposed containment system.
The preliminary design in the FS for the treatment facility
associated with this ground water containment system was
based upon sample results from monitoring wells installed
during the RI. Analytical data obtained from samples of
some of these wells detected the presence of several inorganic
compounds at levels that may exceed standards. However,
there were significant fluctuations in the data between
sampling events at individual monitoring well locations. The
RI attributed the detection of the inorganic constituents to
the sampling technique employed. Samples were not filtered
and the pH was lowered to 2, to preserve the metals. This
procedure would release metals associated with solids in the
unfiltered sample. These solids and there associated metals
would not normally be present in the discharge of a properly
developed production well. The fact that none of these
inorganic compounds were detected in the Katonah Well during
numerous sampling events offers substantive evidence to support
this conclusion.
The treatment facility incorporates metals precipitation
processes to remove these inorganic compounds. Operation and
maintenance of these type processes is very costly and results
in the generation of significant amounts of hazardous sludges
that .must be disposed of in an appropriate manner. Implementation
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of such a system will actually result in an increase in. the
toxicity and volume of contaminants, counter to the statutory
directive requiring a reduction. The alternative is not cost
effective because it does not provide additional protection to
public health or the environment.
Alternative 5; Replacement of Lost Water Resource With
No Site Remediation
Alternative 5 would provide for the relocation of a new well off
site. This well would then be connected to the existing
distribution system of the Bedford Consolidated Water District.
Soil and groundwater on site would not be remediated under
this alternative. The alternative is cost effective but does not
address aquifer restoration. This alternative will remain
implementable to the community/ should their future water needs
continue to increase. However, the selection of this alternative
at this time would basically result in the loss of a prolific
water resource. Neither EPA's groundwater protection strategies/
nor the community's future water needs would be well served
by this alternative. In addition, the statutory directive
in CERCLA seeking a reduction of the toxicity, mobility and
volume of contamination on Superfund sites would be ignored by
the selection of this alternative.
Alternative 6; A New Production Well and Treatment
On Site With an Air Stripper
Alternative 6 is the selected remedy for the Katonah Municipal
Well site. It provides for the installation of a n'ew production
well and on-site treatment with an air stripper prior to
discharge into the Bedford Consolidated Water District
distribution system for use as drinking water. The treatment
system would remove contaminants detected in the Katonah Well at
levels that exceed standards established for the site. It will
meet drinking water standards and enhance aquifer restoration
by pumping and treating contaminated ground water. The
remedy will be effective in protecting human health and the
environment and in reducing the toxicity, mobility and volume
of contamination. It is easily implementable and cost effective.
Detailed discussion of the selected remedy is provided later
in this document.
Alternative 7; Renovation of the Existing Katonah Well
and Treatment On Site With an Air Stripper
Alternative 7 includes a renovation of the existing Katonah
Municipal Well and installation of a treatment system identical
to that developed for the selected remedy. Although estimated to
be slightly cheaper than Alternative 6, this alternative cannot
ensure restoration of historical water yields. The results of a
four week pump test conducted as part of the remedial
investigation indicate that the pumping capacity of the
Katonah Well has deteriorated since it was shut down in 1978.
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Pumping records from 1978 demonstrated that the well had a
pumping capacity of approximately 360 gallons per minute
(gpm) at that time. During the 1987 RI pump test the existing
Katonah Well demonstrated a maximum yield of 210 gpm.
Reduction in the pumping capacity of the Katonah Well is
attributable to deteriorated pumps and to sediment accumulation
in the well. The well was constructed over sixty years ago and
all available records have been lost. A complete inspection of
the well, including a di7e to the bottom, was performed as part
of the RI. It became apparent that significant renovation of the
well and associated pumping facilities will be necessary to
obtain historical water yields, including excavation of an
additional twelve feet in depth. These requirements hinder the
implementability, technical feasibility, and reliability of this
alternative.
VI. SELECTED REMEDY
The selected remedial alternative was arrived at by evaluating
the remedial alternatives presented in the feasibility study by
the consultant Camp Dresser and McKee Inc., in accordance with
the statutory requirements established in CERCLA, and to the
extent practicable, the NCP. The selected remedy is protective
of human health and the environment, cost effective, utilizes
alternative treatment technologies to the maximum extent
practicable to reduce the toxicity, mobility, and volume of
contamination, and attains Federal and State ARARs.
The selected remedy for the Katonah Municipal Well site consists
of the following components:
1. A new 370 gpm production well will be installed
on the peninsula, owned by the City of New York, near
the existing Katonah Well. (See Figure 2.) Contingent
upon a detailed design, this well would be drilled to
the bottom of the aquifer and screened for approximately
one-third of the aquifer thickness. The well will be
comprised of a 12-inch stainless steel casing and
screen. Two pumps will be installed (one operational
and one standby), both capable of delivering water at
the required flow rate at a hydraulic head of 300
feet.
2. A ground water treatment facility will be installed
on the peninsula, owned by the City of New York. The
treatment facility will utilize air stripping for
removal of volatile organic compounds and chlorination
for disinfection. Treated water will then be discharged
to the Bedford Consolidated Water District distribution
system for use as drinking water. Contingent upon a
detailed design, the design criteria for the treatment
facility servicing the 370 gpm production well discharge
will be as in Table 2.
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Air stripping has been proven effective in removing the
contaminant of concern (PCE) to the required level, i.e.
less than 1 ug/1, i.e. nondetectable. Also, a treatability
test performed during the RI demonstrated the applicability
of this alternative treatment technology to the Katonah
site. A four week pump test of the Katonah Well was
conducted to further characterize hydrogeologic and
water quality parameters at the site. Effluent water
was treated by an air stripping column, prior to discharge
to the Muscoot Reservoir. Monitoring of water influent
and effluent to the column demonstrated effective
treatability of site ground water by this method. This
pilot study further delineated expected water quality for
the Katonah site and established that treatment need be
provided only for removal of PCE.
3. A comprehensive water quality monitoring program
will be initiated to ensure a safe drinking
water supply for the community and to determine the
level of aquifer restoration. Monitoring locations
and schedule will be established during the remedial
design stage of the project.
4. A general cleanup of the peninsula area is recommended for
Town implementation. This includes the removal of the
existing pumphouse facility and any trash, maintenance
debris or other material that may adversely affect water
quality at the newly installed production well facility.
The accumulation of these materials resulted from the
poor housekeeping practices maintained by the Town on the
peninsula. The continued use of the peninsula as a
convenient dumping ground and storage area for these and
other possibly hazardous materials should be discontinued.
The selected remedy has been designed as a comprehensive remedial
action for the Katonah Municipal Well site. It addresses
aquifer restoration by means of pumping and treating contaminated
ground water, which will effect aquifer clean up at a more rapid
rate than through natural attenuation without pumping. Results
of a four week pump test conducted as part of the RI indicate
that pumping has significant impact upon contaminant flow
paths within the aquifer. (See Figures 7-9.) Thus, a
pump and treat approach will allow for effective management
of contaminant migration in ground water and will prevent the
discharge of contaminants to the Muscoot Reservoir.
Target treatment levels and standards have been established
for the site and concurrence on these received from the
NYSDEC. Contaminated ground water will be treated to drinking
water quality and distributed to over 25 consumers on a daily
basis. Thus, Maximum Contaminant Levels (MCLs) promulgated
under the Safe Drinking Water Act are the applicable or
relevant and appropriate cleanup levels for the site. However,
there is presently no MCL for the contaminant of concern, PCE.
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There is a Federal Water Quality Criteria of 0.8 ug/1 (45 FR
79318) associated with a 10~6 excess cancer risk for ingestion
of water and aquatic organisms. The Superfund Public Health
Evaluation Manual (October 1986) associates 0.88 ug/1 as the
10~6 excess cancer risk threshold for ingestion of water alone.
CERCLA requires the selection of a remedy that is protective
of human health and the environment, that is cost effective,
and that utilizes permanent solutions or alternative treatment
technologies to the maximum extent practicable. The selected
remedy, air stripping, is an alternative treatment technology
capable of achieving the 10~6 excess cancer risk threshold in a
cost effective manner. However, generally available analytical
techniques offer a detection limit of 1 ug/1 for PCE, making
compliance with a lower target cleanup level technically
impracticable and unenforceable. Thus, in the absence of an'
MCL, the target treatment level for PCE at the Katonah Municipal
Well site will be established as less than 1 ug/1 or nondetectable,
This treatment level is implementable, protective of human
health, and can be achieved in a cost effective manner.
Air emissions from the packed column stripper will consist of
extremely low levels of tetrachloroethylene which will pose
no threat to human health or the environment. Application of 6
NYCRR 212, commonly referred to as Air Guide 1 was considered
applicable or relevant and appropriate in determining acceptable
air emission levels for the site. Calculations performed
during the RI/FS indicate that expected air emission levels
are well below those required by New York Stace.
Source concrol was implemented at the Katonah Municipal Well site
by the Westchester County Department of Health in 1978. Steps
were taken at that time to remove contaminated wastes from the
septic systems of area dry cleaners and to modify disposal
techniques for waste solvents. Additional source control
measures were implemented by thfe Town of Bedford through the
promulgation of stringent aquifer protection ordinances.
Contamination presently existing in the aquifer was characterized
during the remedial investigation as passive or residual
contamination. Further, the RI determined there are no active
sources presently releasing PCE to the aquifer.
The selected remedy is protective of human health and the
environment, complies with legally applicable or relevant
and appropriate requirements in a cost effective manner, and
makes use of alternative treatment technologies to the maximum
extent practicable. The remedy will pump and treat 'ground
water to provide drinking water for the surrounding community
and expedite the reduction and removal of contamination from
the aquifer system.
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t
Location Map of Katonah Municipal Well Site
Katonah Municipal Well Srte. Town of Bedford. New York
-------
KEY;
Soil Boring Location
(J) Monitoring Well Location
•) Boring/Well Coablnation Location
Streaa Saaple Location
Reaervolr
Katonah Municipal Puaiphouse
RESERVOIR
Katonah Municipal Well
Site Layout M-ip
-------
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-------
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-------
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StratiRrtphlt Cro*«-S«clIon •-•
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-18-
103
Historic and Present Concentrations
70
12
24
- Punpinf in 1981
0 - Pusplng in 1987
Figure 6
Observed PCE Concentration In The Katonah
Municipal Well During Puaping
Municipal Veil Site
New York
-------
Rcacrvolr
(200.47)
Figure 8
W.t.r Table Surf
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-21-
Flow P.th Vlthout
Municipal Well Site
New Terk
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-22-
Table 1
Katonah Municipal Well Site
Cost* ($1,000)
Remedial Alternative
1 . No Action
2. Excavation and offsite
soil disposal.
3. Excavation and offsite
incineration of soils.
4. Containment of contam-
inated soil and ground
water.
5. Replacement of lost
water resource with no
site remediation.
6. New production well
facility and treatment
with an air stripper,
on-site.
7. Renovation of existing
Katonah well and air
stripper treatment
on-site.
Capital
0
1,235
3,428
2,835
378
1,365
1,363
Annual 0/M
0
0
0
520
220
296
296
Total PW**
0
1,235
3,428
5,427
2,451
4,155
4,153
* Each of the above alternatives includes costs for required
long term environmental monitoring.
** All total present worth values based on a 30 year project
period.
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-23-
TABLE 2
DESIGN CRITERIA FOR 370-GPK KATONAH WELL WATER
KATONAH, NEW YORK
I. BASIS OF DESIGN
Operation
Flow Rate
Intended Use
II. REMOVAL REQUIREMENTS
24 hrs/day, 365 days/year
370 gpm
Municipal Drinking Water
Contaminant
Tetrachloroethylene (PCE)
III. AIR STRIPPING TOWER
Influent Effluent % Removal
125 ug/L 0.6 ug/L
99.4
Tc^er Diameter
Height (total)
Packing Depth (type)
Hydraulic Loading
AirrWater Vol. Ratio
Stripping Factor
Blower Size
Pump Station No. 2
A ft.
25 ft.
ft. (2-in Tripacks)
28 gpm/ft2
40:1
20
2000 cfm: 5 hp
IV. DISINFECTION
Contact time
wet well
Chlorine dosage, mg/L(lbs/day)
Pumping station: To distribution
30 min.
1500 cu. ft.
4 (18)
2 pumps; 370 gpm
50 hp
300 Ft. TDH
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