REMEDIATION SYSTEM EVALUATION
RISDON CORPORATION
DANBURY, CONNECTICUT
Report of the Remediation System Evaluation,
Site Visit Conducted at the Risdon Corporation Site
January 15,2003
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Office of Solid Waste EPA 542-F-04-027
and Emergency Response September 2004
(5102G) www.epa.gov/tio
clu-in.org/optimization
Remediation System Evaluation
Risdon Corporation
Danbury, Connecticut
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NOTICE AND DISCLAIMER
The U.S. Environmental Protection Agency (U.S. EPA) funded the work described herein and
preparation of this document by GeoTrans, Inc. under General Services Administration contract
GS06T02BND0723 to S&K Technologies, Bremerton, Washington and under EPA contract 68-C-02-092
to Dynamac Corporation, Ada, Oklahoma. Mention of trade names or commercial products does not
constitute endorsement or recommendation for use.
This report has undergone review by the EPA site managers and EPA headquarters staff. For more
infomation about this project, contact: Mike Fitzpatrick (703-308-8411 orfitzpatrick.mike@epa.gov) or
Kathy Yager (617-918-8362 or yager.kathleen@epa.gov).
Risdon RSE Report, April 11, 2003 (Revised September 1, 2004)
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EXECUTIVE SUMMARY
A Remediation System Evaluation (RSE) involves a team of expert hydrogeologists and engineers,
independent of the site, conducting a third-party evaluation of site operations. It is a broad evaluation
that considers the goals of the remedy, site conceptual model, above-ground and subsurface performance,
and site exit strategy. The evaluation includes reviewing site documents, visiting the site for up to 1.5
days, and compiling a report that includes recommendations to improve the system. Recommendations,
including estimates of resulting net cost impacts, are provided in the following four categories:
improvements in remedy effectiveness
reductions in operation and maintenance costs
technical improvements
gaining site closeout
The recommendations are intended to help the site team (the responsible party and the regulators)
identify opportunities for improvements. In many cases, further analysis of a recommendation, beyond
that provided in this report, may be needed prior to implementation of the recommendation. Note that
the recommendations are based on an independent evaluation by the RSE team, and represent the
opinions of the RSE team. These recommendations do not constitute requirements for future action, but
rather are provided for the consideration of all site stakeholders.
The Risdon Manufacturing Corporation facility, located in Danbury, Connecticut at the intersection of
Old Newtown Road and Newtown Road, manufactures cosmetic containers. On-site practices
historically included electroplating, chromating, acid/solvent stripping, degreasing, buffing, polishing,
lacquering, hot stamping, silk screening, and assembly. The facility began operation in 1956, and some
of these practices still continue after a number of facility modifications have been implemented.
Historical manufacturing activities have led to chlorinated hydrocarbon contamination of ground water,
soil, and soil vapor as well as metals contamination of the soil and ground water.
Two separate P&T systems and one soil vapor extraction (SVE) system operate at the facility. Off-site
ground water and soil vapor contamination are present. The primary potential receptors include
residences and commercial buildings potentially susceptible to contaminant vapors and surface water
within 500 feet of known site-related contamination.
The observations and recommendations contained in this report are not intended to imply a deficiency in
the work of either the system designers or operators but are offered as constructive suggestions in the
best interest of the EPA, the public, and the facility. These recommendations have the obvious benefit of
being formulated based upon operational data unavailable to the original designers.
Most recommendations pertain to improved effectiveness. The recommendations are prioritized such
that addressing crucial items, such as controlling potential human exposures controlled and stabilizing
the plume, should be implemented first. Recommendations include the following:
Risdon RSE Report, April 11, 2003 (Revised September 1, 2004)
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High Priority
sample indoor air at surrounding residences, as planned, and add indoor air sampling at
commercial buildings (including the Risdon facility) and install venting systems as necessary
(Recommendation 6.1.1)
develop and implement institutional controls (Recommendation 6.1.2)
as planned, install additional on-site extraction wells to contain ground water contamination at
the site boundary and prevent further off-site migration in both overburden and bedrock (6.1.3)
inspect and rehabilitate, as necessary, the LA ground water recovery wells (6.1.4)
install a new treatment system capable of handling the combined flow from the MFA, LA, and
new extraction wells (6.1.5)
Intermediate Priority
update the site conceptual model (Recommendation 6.1.6)
control migration of vapors in subsurface by enhancing SVE system (Recommendation 6.1.7)
update the ground water model and use regularly to evaluate control of contaminant migration
offered by onsite wells (Recommendation 6.1.8)
delineate the off site plume in both overburden and bedrock (Recommendation 6.1.9)
develop a site exit strategy that includes the set of site conditions that will allow active
remediation (i.e., the P&T and SVE systems as well as off-site remedies) to be discontinued
(Recommendation 6.4.1)
Other recommendations include improvements to O&M and ground water reports, and repairing a
damaged well cap. No recommendations are identified to directly reduce costs. However, the RSE team
has considered cost-effectiveness in determining the scopes for the effectiveness recommendations.
A table summarizing the recommendations, including estimated costs and/or savings associated with
those recommendations, is presented in Section 7.0 of this report.
Risdon RSE Report, April 11, 2003 (Revised September 1, 2004)
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PREFACE
This report was prepared as part of a pilot project conducted by the U. S. EPA Office of Solid Waste
(OSW) and Office of Superfund Remediation and Technology Innovation (OSRTI). The objective of this
project is to conduct Remediation System Evaluations (RSEs) of pump and treat (P&T) systems
operating under the Resource Conservation and Recovery Act (RCRA). The following organizations are
implementing this project.
Organization
Key Contact
Contact Information
USEPA Office of Solid Waste
(U.S. EPA OSW)
Mike Fitzpatrick
5303W
USEPA Headquarters
Ariel Rios Building 1200
Pennsylvania Avenue, N. W.
Washington, DC 20460
phone: 703-308-8411
fitzpatrick.mike@epa.gov
USEPA Office of Superfund
Remediation and Technology
Innovation
(U.S. EPA OSRTI)
Kathy Yager
11 Technology Drive (ECA/OEME)
North Chelmsford, MA 01863
phone: 617-918-8362
fax: 617-918-8427
yager.kathleen@epa.gov
Dynamac Corporation
(Contractor to U.S. EPA)
Daniel Pope
Dynamac Corporation
3601 Oakridge Boulevard
Ada, OK 74820
phone: 580-436-5740
fax: 580-436-6496
dpope@dynamac.com
GeoTrans, Inc.
(Contractor to Dynamac)
Doug Sutton
GeoTrans, Inc.
2 Paragon Way
Freehold, NJ 07728
phone: 732-409-0344
fax: 732-409-3020
dsutton@geotransinc.com
Risdon RSE Report, April 11, 2003 (Revised September 1, 2004)
111
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TABLE OF CONTENTS
EXECUTIVE SUMMARY i
PREFACE iii
TABLE OF CONTENTS iv
1.0 INTRODUCTION 1
1.1 PURPOSE 1
1.2 TEAM COMPOSITION 2
1.3 DOCUMENTS REVIEWED 2
1.4 PERSONS CONTACTED 3
1.5 SITE LOCATION, HISTORY, AND CHARACTERISTICS 4
1.5.1 LOCATION AND HISTORY 4
1.5.2 POTENTIAL SOURCES 5
1.5.3 HYDROGEOLOGIC SETTING 6
1.5.4 POTENTIAL RECEPTORS 7
1.5.5 DESCRIPTION OF GROUND WATER PLUME 7
2.0 SYSTEM DESCRIPTION 9
2.1 SYSTEM OVERVIEW 9
2.2 EXTRACTION SYSTEM 9
2.3 TREATMENT SYSTEM 10
2.4 MONITORING PROGRAM 10
3.0 SYSTEM OBJECTIVES, PERFORMANCE AND CLOSURE CRITERIA 12
3.1 CURRENT SYSTEM OBJECTIVES AND CLOSURE CRITERIA 12
3.2 TREATMENT PLANT OPERATION STANDARDS 13
4.0 FINDINGS AND OBSERVATIONS FROM THE RSE SITE VISIT 15
4.1 FINDINGS 15
4.2 SUBSURFACE PERFORMANCE AND RESPONSE 15
4.2.1 WATER LEVELS 15
4.2.2 CAPTURE ZONES 16
4.2.3 CONTAMINANT LEVELS 17
4.3 COMPONENT PERFORMANCE 18
4.3.1 EXTRACTION SYSTEM WELLS, PUMPS, AND HEADER 18
4.3.2 AIR STRIPPER 19
4.3.3 EFFLUENT/DISCHARGE 19
4.3.4 SYSTEM CONTROLS 19
4.4 COMPONENTS OR PROCESSES THAT ACCOUNT FOR MAJORITY OF COSTS 20
4.4.1 UTILITIES 20
4.4.2 NON-UTILITY CONSUMABLES 20
4.4.3 LABOR 20
4.4.4 OTHER COSTS 20
4.5 RECURRING PROBLEMS OR ISSUES 21
4.6 REGULATORY COMPLIANCE 21
Risdon RSE Report, April 11, 2003 (Revised September 1, 2004) iv
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4.7 TREATMENT PROCESS EXCURSIONS AND UPSETS, ACCIDENTAL CONTAMINANT/REAGENT
RELEASES 21
4.8 SAFETY RECORD 21
5.0 EFFECTIVENESS OF THE SYSTEM TO PROTECT HUMAN HEALTH AND THE
ENVIRONMENT 22
5.1 GROUND WATER 22
5.2 SURFACE WATER 22
5.3 AIR 22
5.4 SOILS 23
5.5 WETLANDS AND SEDIMENTS 23
6.0 RECOMMENDATIONS 24
6.1 RECOMMENDATIONS TO IMPROVE EFFECTIVENESS 24
6.1.1 PERFORM VAPOR SAMPLING WITHIN BUILDINGS, INSTALL VENTING SYSTEMS As
APPROPRIATE 24
6.1.2 DEVELOP AND IMPLEMENT INSTITUTIONAL CONTROLS 24
6.1.3 ADD EXTRACTION WELLS TO PROVIDE HYDRAULIC CONTAINMENT NEAR THE PROPERTY
BOUNDARY 25
6.1.4 INSPECT AND REHABILITATE WELLS AND PIPING FOR THE LA EXTRACTION SYSTEM . 26
6.1.5 REPLACE EXISTING TWO TREATMENT SYSTEMS WITH ONE NEW SYSTEM CAPABLE OF
TREATING A HIGHER FLOWRATE 26
6.1.6 UPDATE THE SITE CONCEPTUAL MODEL 27
6.1.7 RECONFIGURE SVE SYSTEM (ADD NEW SVE WELLS IN SELECTED AREAS) 28
6.1.8 UPDATE/VALIDATE GROUND WATER FLOW MODEL AFTER NEW EXTRACTION WELLS
ARE ON-LINE 28
6.1.9 PERFORM OFFSITE PLUME DELINEATION 29
6.2 RECOMMENDATIONS TO REDUCE COSTS 30
6.3 MODIFICATIONS INTENDED FOR TECHNICAL IMPROVEMENT 30
6.3.1 INSTITUTE QUARTERLY AND ANNUAL OPERATIONS REPORTS 30
6.3.2 REPAIR SURFACE CAP FoRMW-12 31
6.4 CONSIDERATIONS FOR GAINING SITE CLOSE OUT 32
6.4.1 DEVELOP AN EXIT STRATEGY 32
6.5 SUGGESTED APPROACH TO IMPLEMENTATION 33
7.0 SUMMARY 34
List of Tables
Table 7-1. Cost summary table
List of Figures
Figure 1-1. Area Surrounding the Risdon Facility
Figure 1-2. Geologic Cross-Section
Figure 1 -3. Extent of VOC Contamination Based on the September 2001 Sampling Event and the 2002
Off-Property Soil Vapor and Ground Water Sampling Report
Figure 4-1. Potentiometric Surface Map Provided in the January 2003 Ground Water Monitoring Report
Figure 6-1. Recommended Locations for Additional Extraction Wells
Risdon RSE Report, April 11, 2003 (Revised September 1, 2004)
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1.0 INTRODUCTION
1.1 PURPOSE
During fiscal years 2000, 2001, and 2002 Remediation System Evaluations (RSEs) were conducted at 24
Fund-lead pump and treat (P&T) sites (i.e., those sites with P&T systems funded and managed by
Superfund and the States). Due to the opportunities for system optimization that arose from those RSEs,
EPA OSRTI and OSW are performing a pilot study of conducting RSEs at RCRA sites. During fiscal
year 2003, RSEs at up to five RCRA sites are planned in an effort to evaluate the effectiveness of this
optimization tool for this class of sites. GeoTrans, Inc. is conducting these evaluations, and
representatives from EPA OSW and OSRTI are attending the RSEs as observers.
The Remediation System Evaluation (RSE) process was developed by the US Army Corps of Engineers
(USAGE) and is documented on the following website:
http://www.environmental.usace.armv.mil/library/guide/rsechk/rsechk.html
A RSE involves a team of expert hydrogeologists and engineers, independent of the site, conducting a
third-party evaluation of site operations. It is a broad evaluation that considers the goals of the remedy,
site conceptual model, above-ground and subsurface performance, and site exit strategy. The evaluation
includes reviewing site documents, visiting the site for 1 to 1.5 days, and compiling a report that includes
recommendations to improve the system. Recommendations with cost and cost savings estimates are
provided in the following four categories:
improvements in remedy effectiveness
reductions in operation and maintenance costs
technical improvements
gaining site closeout
The recommendations are intended to help the site team (the responsible party and the regulators)
identify opportunities for improvements. In many cases, further analysis of a recommendation, beyond
that provided in this report, may be needed prior to implementation of the recommendation. Note that
the recommendations are based on an independent evaluation by the RSE team, and represent the
opinions of the RSE team. These recommendations do not constitute requirements for future action, but
rather are provided for the consideration of all site stakeholders.
The Risdon Corporation facility was selected by EPA OSW based on progress made toward
Environmental Indicators and comments from the EPA project manager for the site . This report
provides a brief background on the site and current operations, a summary of the observations made
during a site visit, and recommendations for changes and additional studies. The cost impacts of the
recommendations are also discussed.
Risdon RSE Report, April 11, 2003 (Revised September 1, 2004)
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1.2
TEAM COMPOSITION
The team conducting the RSE consisted of the following individuals:
Rob Greenwald, Hydrogeologist, GeoTrans, Inc.
Peter Rich, Civil and Environmental Engineer, GeoTrans, Inc.
Doug Sutton, Water Resources Engineer, GeoTrans, Inc.
The RSE team was also accompanied by the following observers:
Kathy Yager from EPA OSRTI
Deborah Sherer and Kristie Moore from EPA OSW
EPA OSRTI and EPA OSRTI are jointly conducting this RSE Pilot Study for RCRA sites.
1.3
DOCUMENTS REVIEWED
Author
CT Bureau of Waste
Management, Site
Remediation and Closure
Division
Groundwater Technology
Groundwater Technology
A.T. Kearny, Inc.
Haley & Aldrich, Inc.
Haley & Aldrich, Inc.
Haley & Aldrich, Inc.
Woodard & Curran, Inc.
Woodard & Curran, Inc.
Woodard & Curran, Inc.
US EPA
Woodard & Curran, Inc.
Date
9/12/1990
10/22/1991
4/16/1993
4/14/1995
4/1995
2/1996
2/1997
1/1999
8/1999
11/5/1999
6/23/2000
10/30/2000
Title
Preliminary Assessment Report, Risdon Corporation
Status Report, Remedial Activities for Risdon Corporation
Quarterly Report, 12/1 1/1992 through 3/3 1/1993
Initial Assessments and Stabilization Evaluation of RCRA
Facilities, Risdon Corporation
Summary Report of Investigative and Remedial Work,
Risdon Manufacturing Company
Groundwater and Remedial Systems Monitoring 1995
Annual Report, Risdon Manufacturing Company
1996 Annual Remediation and Monitoring Report
RCRA Facility Investigation Report
Interim Corrective Measure Evaluation Report, Risdon
Corporation
RCRA Corrective Action Environmental Indicators
RCRA Corrective Action Environmental Indicator
Determination at Risdon-AMS Corporation
Transmittal of Response to Comments of Environmental
Indicator Determination and Interim Measures Evaluation
Report for Risdon Corporation
Risdon RSE Report, April 11, 2003 (Revised September 1, 2004)
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Author
Woodard & Curran, Inc.
US EPA
Woodard & Curran, Inc.
Woodard & Curran, Inc.
Woodard & Curran, Inc.
Woodard & Curran, Inc.
Tetra Tech EMI
Woodard & Curran, Inc.
Woodard & Curran, Inc.
Woodard & Curran, Inc.
Woodard & Curran, Inc.
Woodard & Curran, Inc.
CTDPH
Woodard & Curran, Inc.
Woodard & Curran, Inc.
Woodard & Curran, Inc.
Date
11/30/2000
2/15/2001
4/20/2001
10/5/2001
4/30/2001
11/6/2001
11/17/2001
12/21/2001
2/12/2002
2/14/2002
4/11/2002
4/18/2002
6/12/2002
6/28/2002
9/26/2002
!/2003
Title
Transmittal of Response to Comments of RCRA Facility
Investigation Report for Risdon Corporation
RCRA Corrective Action Environmental Indicator
Determination at Risdon-AMS Corporation
Response to EPA's RFI Comment 1
Off-Property Soil Vapor Survey Work Plan
Evaluation of Potential Indoor Air Quality Impacts and
Soil Vapor Survey Work Plan
Response to USEPA Comments on Off-Property Soil
Vapor Survey Work Plan
Health and Safety Plan for Field Oversight and Split
Spoon Sampling
Baseline Groundwater Monitoring Report and Revised
Groundwater Monitoring Plan
MFA SVE System Initial Operations Evaluation Report
Revised On-Property Soil Vapor Survey Work Plan
Groundwater Monitoring Report, January - March 2002
Off-Property Soil Vapor and Groundwater Sampling
Report
Health Consultation, Vapor Intrusion Potential at
Properties Adjacent to Former Risdon Corporation Facility
On-Property Soil Vapor Survey Report
Groundwater Monitoring Report, July 2002
Groundwater Monitoring Report, October 2002
1.4
PERSONS CONTACTED
The following individuals associated with the site were present for the site visit:
Kenny Gulledge - Crown Cork & Seal Company, Inc. (parent company of Risdon Corporation)
Project Manager, Department of EH&S
Gilbert Ryan, PE - Woodward & Curran
Project Manager
Risdon RSE Report, April 11, 2003 (Revised September 1, 2004)
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Carolyn Casey - USEPA Region 1
Project Manager
Vinnie Mastriani - Risdon Plant
Wastewater Plant Operator
1.5 SITE LOCATION, HISTORY, AND CHARACTERISTICS
1.5.1 LOCATION AND HISTORY
The Risdon Manufacturing Corporation facility, located in Danbury, Connecticut at the intersection of
Old Newtown Road and Newtown Road, manufactures cosmetic containers. On-site practices
historically included electroplating, chromating, acid/solvent stripping, degreasing, buffing, polishing,
lacquering, hot stamping, silk screening, and assembly. The facility began operation in 1956, and some
of these practices still continue after a number of facility modifications have been implemented.
Historical manufacturing activities have led to chlorinated hydrocarbon contamination of ground water,
soil, and soil vapor as well as metals contamination of the soil and ground water.
The property consists of 5-acre manufacturing facility surrounded by paved parking areas, including a
paved parking area to the west of the facility that overlies a former surface impoundment area (the
"lagoon area"). Figure 1-1 presents a map of the Risdon property and the surrounding area. The area
surrounding the facility is primarily commercial or light industrial with interspersed residences. A
Medsource facility is located across Old Newtown Road to the northwest, a residence is also located on
Old Newtown Road to the north, and office space and a private residence/private iron works facility is
located to the northwest on Broad Street. The Still River is located beyond these properties to the
northwest, approximately 100 feet from the Risdon property.
A brief summary of the site history and environmental activities are summarized below.
-1956 disposal of metal hydroxide wastewater to lagoons commences
1982 beginning of the investigative work and closure of the former wastewater lagoons; all
material from the lagoons was removed to the water table (approximately 14 feet below
grade)
1987 subsurface investigation began in order to fulfill USEPA post-closure requirements
1989-1990 ground water quality investigation in the area of the former wastewater lagoons and
design of a ground water and soil remediation system
1990 installation and startup of three ground water recovery wells in the former lagoon area
(LA) with water treated by an air stripper
1992 further investigation of possible source areas including the LA and the metals finishing
area (MFA)
Installation of a soil vapor extraction system and an air/steam sparging system in the LA
(the sparging system never operated at full capacity and has not operated at all after
October 1995)
1993 installation and startup of a soil vapor extraction (SVE) and pump and treat (P&T)
system in the MFA
Risdon RSE Report, April 11, 2003 (Revised September 1, 2004)
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9/1993 replacement of 1,1,1 -trichloroethane (1,1,1 -TCA) for degreasing with trichloroethene
(TCE)
1994 placement of an asphalt cap over the LA and addition of 6 ground water recovery wells
to the MFA remedy
1996 comprehensive ground water monitoring event
1997-1998 supplemental investigative work for the RCRA Facility Investigation report including
pump testing and a bedrock investigation
1/1999 RCRA Facility Investigation Report submitted to EPA
8/1999 interim Corrective Measure Evaluation Report submitted to EPA suggesting the
installation of two additional ground water extraction wells
11/1999 environmental Indicator Determination Checklist submitted to EPA
6/2000 LA SVE system was shut down due to a blower failure and has not been restarted due to
the relatively low mass removal prior to the failure
2/2001 public water supply survey submitted to EPA
12/2001 Baseline Ground Water Monitoring Report and Revised Ground Water Monitoring Plan
submitted to EPA
4/2002 Off-Property Soil Vapor and Ground Water Sampling Report submitted to EPA
demonstrating contamination has migrated off site resulting in elevated concentrations of
chlorinated hydrocarbons in off-site soil vapor and ground water contamination
6/2002 On-Property Soil Vapor Survey Report submitted to EPA
Health Consultation conducted by U.S. Department of Health and Human Services
submitted to EPA recommending indoor air sampling at adjacent residences
1.5.2
POTENTIAL SOURCES
Although 29 areas of concern (AOCs) have been identified on site, these AOCs can be grouped into two
general source areas: the lagoon area (LA) and the metal finishing area (MFA).
The LA consists of former lagoons where metal hydroxide waste was discharged between 1956 and
1982. In 1982, the lagoons were closed and the material in them was excavated to the water table (an
approximate depth of 14 feet below grade). As of September 2001, contamination from chlorinated
solvents, primarily 1,1,1-TCA and its degradation products (i.e., 1,1-dichloroethane and 1,1-
dichloroethene) remains in concentrations indicative of dense non-aqueous phase liquid (DNAPL).
Specifically, 1,1,1-TCA concentrations in four wells (MW-6, MW-9, MW-12, and MW-304) have been
found at concentrations exceeding 1% of its solubility. DNAPL in the LA may provide a continuing
source of dissolved ground water and soil vapor contamination.
The degreasing operations appear to be the primary sources of contamination in the MFA. Facility
improvements and changes in operation beginning in 1992 (including removal of all but one degreaser
and placement of the remaining degreaser in a room with a stainless steel floor and berm) have reduced
or eliminated the likelihood of additional releases of contaminants to the subsurface in the MFA.
However, as with the LA, ground water concentrations are indicative of DNAPL, which may serve as a
continuing source of dissolved ground water and soil vapor contamination. Evidence for DNAPL is
provided both in the magnitude and vertical extent of contamination. Sampling and analysis of
Risdon RSE Report, April 11, 2003 (Revised September 1, 2004)
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monitoring wells in the MFA in 1996 resulted in concentrations of 1,1,1-TCA, TCE, and PCE that
exceeded 100,000 ug/1, 40,000 ug/1, and 70,000 ug/1, respectively. All of these maximum concentrations
for the respective compounds exceed 1% of the solubilities. Furthermore, concentrations of TCE as high
as 34,000 ug/1 have been found in MW-508C, which is a deep bedrock well. In the absence of strong
vertical hydraulic gradients, the presence of elevated concentrations at depth are suggestive of DNAPL
that is descending due to a density that is greater than the surrounding ground water. Although ground
water monitoring for chlorinated hydrocarbons also occurred in September 2001, monitoring wells in the
MFA were not sampled. However, data from this more recent sampling event reveal continued elevated
concentrations of TCE downgradient of the MFA (60,000 ug/L in MW-111) and in bedrock (23,000 ug/1
inMW-508C).
Chlorinated hydrocarbon contamination in the ground water from both the LA and MFA also serves as a
source of potential soil vapor contamination both on and off site.
Ground water also has elevated concentrations of metals such as copper and zinc. There does not appear
to be an ongoing source of VOC ground water contamination from current practices at the facility, but a
limited number of soil samples from 1994 hand augers in the MFA had Toxicity Characteristic Leaching
Procedure (TCLP) test results for some metals that exceed the relevant Connecticut Pollutant Mobility
Criteria (Haley and Aldrich, 1995).
1.5.3 HYDROGEOLOGIC SETTING
The site is located to the east of the Still River, which flows north past the site to its confluence with the
Housatonic River. The area receives approximately 50 inches of rainfall per year and drainage is to the
north along the Still River toward the Housatonic River. The site elevation ranges from approximately
296 feet above mean sea level (MSL) to 308 feet MSL (Woodard and Curran, January 1999). Subsurface
material generally consists of fill overlying glacio-lacustrine deposits, glacial till deposits, and weathered
rock over bedrock. Due to variations in depositional activity some strata are not present in all locations.
The fill primarily consists of sand and gravel, the glacio-lacustrine deposits primarily consist of sand and
silty clay, and the till primarily consists of sands with cobbles or boulders (Haley and Aldrich, April
1995). In general, the unconsolidated glacio-lacustrine sediments and weathered bedrock are considered
to form two interconnected aquifers. At the facility, the depth to bedrock is approximately 20 to 30 feet
below ground surface (bgs). Figure 1-2 depicts a representative cross-section of the subsurface. The
orientation of the cross-section is provided in Figure 1-3. Bedrock elevation decreases to the north
(Woodard and Curran, January 1999).
The depth to ground water beneath the facility is approximately 10 feet bgs. Ground water flows to the
north along the Still River toward a wetland approximately one half-mile to the north of the facility, and
eventually into the Still River. Pumping test data at multiple wells interpreted with the Cooper Jacob
method suggest that hydraulic conductivity in both the unconsolidated sediments and the weathered
bedrock ranges from approximately 13 ft/day to 130 ft/day. The hydraulic conductivity of the competent
bedrock is on the order of 1 ft/day or less (Woodard and Curran, January 1999).
Site documents (Woodard and Curran, January 1999) suggest that vertical ground water flow is affected
by the till layer and the presence of competent bedrock. This document suggests that, where present, the
till layer inhibits vertical flow into the bedrock. It also suggests that the low hydraulic conductivity of
the competent bedrock further limits downward flow. Regardless, the bedrock elevation decreases to the
north, and as indicated in the subsequent sections of this report, ground water contamination has been
found with increasing depth to the north suggesting downward contaminant migration.
Risdon RSE Report, April 11, 2003 (Revised September 1, 2004)
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1.5.4 POTENTIAL RECEPTORS
The ground water in the area surrounding the facility has a GB classification, which designates uses for
industrial process water and cooling water. It is presumed unsuitable for human consumption without
treatment. As a result, the primary potential receptors of concern for ground water contaminated with
volatile organic compounds (VOCs) such as TCE and TCA are surface water and indoor air. The Still
River and the wetland to the north of the site are the potential surface water receptors. Site documents
indicate that the Still River has a Class B designation, which means that designated uses include fish and
wildlife habitat, recreational use, agricultural and industrial supply, and other legitimate uses including
navigation. The various buildings in the area, including residences with basements, are potential indoor
air receptors. Specifically, Connecticut Department of Public Health has evaluated indoor air quality
concerns at five properties downgradient of the site:
Residence, Old Newtown Road
Residence, Broad Street
Commercial, 4 Old Newtown Road
Commercial, 11 Old Newtown Road
Commercial, Augusta Drive
The Risdon facility itself is also a potential receptor for indoor VOC vapors. These potential indoor air
receptors are discussed further in Section 5.0 of this report.
1.5.5 DESCRIPTION OF GROUND WATER PLUME
Ground water contamination from both VOCs and inorganics such as metals and cyanide are present.
The VOC plumes are discussed first, followed by the inorganic plumes. These discussions are limited to
the extent of the plumes and the concentrations within the plumes. A discussion of how the
contamination relates to potential receptors and the applicable remediation standards is included in
Section 5.0 of this report.
VOC plumes
The last comprehensive round of ground water sampling for VOCs (including chlorinated solvents)
occurred in August 1996, and the results are summarized in the Annual Remediation and Monitoring
Report (Haley and Aldrich, February 1997) and the RCRA Facility Investigation Report (Woodard and
Curran, January 1999). Subsequent monitoring for VOCs also occurred in September 2001 and October
2002 as well as during the Off-Property Soil Vapor and Groundwater Sampling Report (Woodard and
Curran, April 2002). The data indicate that ground water plumes of chlorinated hydrocarbons originate
in both the LA and MFA areas and extend offsite. A site map indicating the extent and magnitude of
contamination is presented in Figure 1-3. Concentrations are greatest in the MFA and along the
northeastern (downgradient) boundary of the site. As indicated from direct-push samples GW-1A, GW-
1B, and GW-1C, VOC contamination extends at least 500 feet beyond the site to the northeast toward the
commercial property at 4 Old Newtown Road as well as the other commercial buildings and the wetland
further downgradient. Ground water contamination also extends off-property toward the private
residence on Old Newtown Road to the north, where samples were collected from MW-15 and the direct-
push locations GW-2A and GW-2B.
Along the northeastern boundary of the Risdon property, near the MW-508 cluster, the TCE
concentrations increase with depth. The 1996 data from the MW-508 cluster showed a TCE
concentration of 340 ug/L between 7 and 12 feet bgs, a concentration of 5,100 ug/L between 16 and 19
Risdon RSE Report, April 11, 2003 (Revised September 1, 2004)
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feet bgs, and a concentration of 41,000 ug/L between 34 and 49 feet bgs. Similar increases in
concentration with depth were also evident in the 2001 and 2002 sampling.
Inorganics Plumes
The inorganic ground water contamination is primarily limited to cyanide contamination in MW-15,
copper contamination in the LA, and beryllium, copper, nickel, silver, and zinc contamination along the
northeastern boundary of the site (MW-111, MW-113, and MW-601B). The extent of inorganic
contamination in ground water downgradient of the site has not been defined.
Risdon RSE Report, April 11, 2003 (Revised September 1, 2004)
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2.0 SYSTEM DESCRIPTION
2.1 SYSTEM OVERVIEW
There are two separate P&T systems currently operating:
Lagoon Area (LA) System. Operating since 1990, this system currently includes ground
water extraction/treatment but no SVE.
Metal Finishing Area (MFA) System. Operating since 1993, this system includes ground
water extraction/treatment plus SVE.
In 1992 a soil vapor extraction (SVE) and air sparging component were added to the LA. The air
sparging did not operate at full scale due to fouling problems and was shut off permanently in 1995. The
SVE system included 17 four inch diameter wells. By 1996 the SVE system was recovering only a small
amount of mass (<0.5 Ibs of VOCs per day). The SVE system was shut off in June 2000 when the 10 HP
blower malfunctioned. The blower was not repaired or replaced due to the cost of the blower and the low
VOC recovery rate of the system.
Details of the current LA system and MFA system are provided below.
2.2 EXTRACTION SYSTEM
LA System
The LA system began operation in 1990 with ground water extraction at 3 wells installed to the bedrock
surface, approximately 36 to 38 feet bgs (RW-1 to RW-3). The extraction system is intended to provide
hydraulic containment of contamination originating from the LA, with a design extraction rate of 3 gpm
per well (total design extraction rate from the three wells is 9 gpm). The extraction wells are located in
the parking lot area west of the site, within underground vaults. The wells have above-ground centrifugal
pumps (which apparently replaced submersible pumps shown in the design drawings) operating based on
down-hole Warrick level control probes. Separate 1-inch diameter galvanized steel lines for each well
route the extracted water to the interior of the warehouse building where each line has a throttling valve,
sampling port and flow meter. The lines are then combined in a 2-inch diameter header and routed to the
air stripper.
MFA System
The MFA remediation system began operation in May 1993 with 6 dual-phase extraction wells (RVW-
101, RVW-103 through RW-106, and RW-108) and 2 ground water recovery wells (RW-101C and RW-
108A). Six new 4-inch diameter ground water recovery wells were installed in 1994 (RW-302, RW-303,
and RW-401 through RW-404), and ground water recovery from the dual-phase wells was discontinued.
Therefore, ground water extraction currently occurs from 8 recovery wells, all of which are located
within the production and wastewater treatment areas of the enclosed Risdon building. These wells have
pneumatic extraction pumps that discharge when filled (Woodard and Curran, April 2001).
Risdon RSE Report, April 11, 2003 (Revised September 1, 2004)
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The 6 previously used dual-phase (air and liquid) extraction wells are now used solely as SVE wells, and
two additional vapor recovery wells (VES-102 and VES-109) have also been added. All 8 wells are two
inches in diameter. In September 2001 an evaluation of the SVE system indicated PID readings of 0 in
discharge vapor from all 8 wells. Since 1995 system operation has consisted of cycling groups of wells
on and off (Woodard and Curran, April 2001).
2.3 TREATMENT SYSTEM
LA System
Treatment for VOCs is performed with a packed tower air stripper. The air stripper was designed for 15
gpm with about 35 mg/1 total VOC influent and 2 mg/1 total VOC effluent. It has a 1 HP blower
producing about 226 scfm. The air stripper effluent is pumped from a transfer tank to the plant pH
neutralization system prior to discharge to the POTW. The pH neutralization system is operating at
about 20 gpm during plant operating hours which is near its capacity. The air stripper emissions are
vented directly to the atmosphere because VOC mass released is well below the general limit of 15
tons/yr for individual pollutants (CTDEP RSCA 22a-174-3(a)(l)(D)) and below the limits for specific
hazardous air pollutants (limits are identified in the Haley & Aldrich "Summary Report of Investigative
and Remedial Work" dated April 1995).
MFA System
All of the treatment equipment associated with this system are located in the production and wastewater
treatment areas within the enclosed Risdon building. The extracted ground water is routed to a strainer
and then to a Aeromix Systems Breeze diffused aeration type air stripper with a 1.75 HP blower. The
stripper has a hydraulic capacity of 175 gpm but is limited by treatment efficiency due to air flow and
retention time. From the diffused aeration unit, the water is routed to the plant cyanide destruction and
metals removal system. This plant system is treating about 10 gpm during plant operating hours and is
reported to be near capacity. Effluent from those plant treatment processes is then discharged to the
POTW. VOC vapors from the diffused aerator are routed through two 55 gallon VGAC units. The MFA
system operates only during the facility operating schedule because it relies on the labor associated with
the plant wastewater system.
Extracted vapors from the SVE wells were initially treated with a catalytic oxidation unit. Off-gas
treatment was discontinued in November 1994 because untreated emissions were in compliance with
limits identified in the Haley & Aldrich "Summary Report of Investigative and Remedial Work" dated
April 1995.
2.4 MONITORING PROGRAM
Monitoring of the treatment processes is relatively limited. Influent samples are not regularly collected
and analyzed for any of the ground water or vapor recovery systems. Effluent of all treated water that is
discharged to the POTW was previously sampled and analyzed monthly for total toxic organics, but this
has been reduced to semi-annually. Samples are analyzed for copper and silver weekly, and sampling for
chromium, nickel, and cyanide has been reduced to semi-annual sampling. Air sampling for the SVE
systems and the air stripper off-gas is not monitored because it is well below the reported requirement of
15 tons/year total. All process sampling is conducted by the facility water treatment plant operator.
Risdon RSE Report, April 11,2003 (Revised September 1, 2004) 10
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Ground water monitoring was restarted in September 2001 with a baseline event. The previous
comprehensive sampling event was in 1996. The sampling locations and frequencies for the ground
water monitoring plan are summarized in the following table.
Sampling Frequency
Sampling Parameters
Monitoring Wells
Quarterly for one year
(9/2001 through 10/2002)
13 Priority Pollutant Metals and
Cyanide
LA
MW-1, MW-2, MW-3, MW-8, MW-10,
MW11,MW-15
MFA
MW-111, MW-113, MW-601B
Annually
VOCs
LA
MW-1, MW-2, MW-3, MW-9, MW-10,
MW-11,MW-14,MW-15
MFA
MW-111, MW-112, MW-508, MW-
508C, MW-601B
All samples are collected with low-flow sampling. Metals are analyzed using EPA Method 6010B
(7470A for mercury and 7060A for arsenic), cyanide is analyzed using 901 OB, and VOCs are analyzed
using 8021C. Now that quarterly monitoring for metals and cyanide has been completed for one year
with consistent results, the facility and its contractors have recommended reducing the monitoring for
metals and cyanide to annually. Therefore, VOCs, metals, and cyanide will be sampled and analyzed in a
single annual event to occur in September of each year.
Ground water elevations are collected from all site monitoring and ground water recovery wells and from
the 7 Medsource monitoring wells during each sampling event. The headspace of each well is monitored
with a PID prior to measuring the ground water elevation.
The ground water monitoring and elevation measurement results are summarized in monitoring reports.
At the time of the RSE visit, the facility contractor received comments from EPA on a work plan for
indoor air sampling. The details of this plan and the comments have not been reviewed by the RSE team
and are not discussed in this report.
Risdon RSE Report, April 11, 2003 (Revised September 1, 2004)
11
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3.0 SYSTEM OBJECTIVES, PERFORMANCE AND CLOSURE
CRITERIA
3.1
CURRENT SYSTEM OBJECTIVES AND CLOSURE CRITERIA
Currently, the site is in the investigation phase; however, due to detected contaminant concentrations in
the subsurface, specifically ground water, Interim Corrective Measures (ICMs) have been implemented at
the site since 1990. The objective for the Lagoon Area (LA) ICM is to contain and prevent migration of
VOC contaminated ground water from the former lagoon area. The objective of the Metals Finishing
Area (MFA) ICM is to reduce contaminant concentrations in the source area and to contain/prevent
migration of contaminants from the source area via ground water flow.
The overall remedial objective for the facility is to achieve an EPA-approved determination of
Completion of Corrective Action Activities and terminate interim status as a RCRA land disposal
facility. The path to completion involves the typical phases of investigation and remediation under the
RCRA Corrective Action Program, which include investigating the site, assessing risk, developing media
protection standards and objectives, performing a Corrective Measures Study, implementing the selected
Corrective Measure, and final site closure/completion. In addition to the overall objective, the facility
also has the short-term objective of achieving site stabilization through the demonstration of achievement
of Environmental Indicators CA725 - Current Human Exposures Under Control and CA750 - Migration
of Contaminated Groundwater Under Control.
In accordance with Section 22a-133k-l(b) of the Regulations of Connecticut State Agencies, the CTDEP
Remediation Standard Regulations (RSRs) are not directly applicable to the facility; however, the criteria
and standards have been used by the facility and EPA as guidelines. In that regard and with respect to
ground water, and given that ground water in this area is classified as GB, the following criteria are being
used:
ensure that impacted ground water does not interfere with any existing uses of ground
water (currently there are no identified uses of ground water within the boundaries of the
plume); and
demonstrate compliance with the surface water protection criteria and volatilization
criteria (see the following table):
Constituent of Concern
Surface Water
Protection Criteria
Industrial/Commercial
Volatilization Criteria
Residential
Volatilization Criteria
VOCs
1,1 Dichloroethene (1,1 DCE)
Tetrachloroethene (PCE)
1,1,1 Trichloroethane (1,1,1 TCA)
Trichloroethene (TCE)
96ug/L
88ug/L
62,000 ug/L
2,340 ug/L
6 ug/L
3,820 ug/L
50,000 ug/L
540 ug/L
I ug/L
1,500 ug/L
20,400 ug/L
219 ug/L
Risdon RSE Report, April 11, 2003 (Revised September 1, 2004)
12
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Constituent of Concern
Surface Water
Protection Criteria
Industrial/Commercial
Volatilization Criteria
Residential
Volatilization Criteria
Inorganics
Total Cyanide
Arsenic
Total Beryllium
Total Copper
Total Nickel
Total Silver
Total Zinc
0.052 mg/L
0.004 mg/L
0.004 mg/L
0.048 mg/L
0.88 mg/L
0.0 12 mg/L
0.123 mg/L
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Information is taken from the CTDEP Remediation Standard Regulations
It should be noted that demonstration of the volatilization criteria is achieved by demonstrating that there
are no risks to applicable receptors via the vapor migration pathway to indoor air (in addition to ground
water data, this can be accomplished through the use of indoor air or soil vapor samples). If this
approach is followed, then achievement of the volatilization criteria for ground water is not relevant.
Compliance with the surface water protection criteria is demonstrated by an average of the plume or
compliance at the point of discharge of the plume to surface water; therefore, achievement of the criteria
at each well is not needed.
As indicated above, the objectives of the current ICMs are hydraulic containment and to some extent
source zone containment reduction. To demonstrate compliance with the two Els and ultimately the
RSRs, additional investigation of remedial alternatives/enhancements will be required.
3.2
TREATMENT PLANT OPERATION STANDARDS
Water from the two P&T systems and the treated wastewater from the plant are discharged to the POTW.
The discharge standards included in the August 1999 Interim Corrective Measure Evaluation Report are
presented in the following table.
Parameter
Cadmium
Chromium, Total
Copper
Nickel
Silver
Zinc
Cyanide, Amenable
Cyanide, Total
pH
Total Oil & Grease
Total Toxic Organics
Average Monthly Limit
0. 1 mg/L
1.0 mg/L
1.0 mg/L
1.0 mg/L
0. 1 mg/L
1.0 mg/L
0. 1 mg/L
0.65 mg/L
6.0-9.5
50.0 mg/L
-
Maximum Daily Limit
0.5 mg/L
2.0 mg/L
2.0 mg/L
2.0 mg/L
0.43 mg/L
2.0 mg/L
0.2 mg/L
1.2 mg/L
-
100.0 mg/L
2. 13 mg/L
No limits are stated for aluminum, iron total suspended solids, and methylene chloride
Risdon RSE Report, April 11, 2003 (Revised September 1, 2004)
13
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The permit requirements listed in the ICM Evaluation Report include variable sampling frequencies from
weekly to annually depending on the parameter. As stated in Section 2.4 of this report, the facility
reported that they take effluent samples semi-annually for most parameters. Both silver and copper are
sampled weekly.
An NPDES permit was issued to the site but was discontinued in 2000. Limits were similar to the POTW
limits except TTO, which had a limit of 0.25 mg/L.
Risdon RSE Report, April 11,2003 (Revised September 1, 2004) 14
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4.0 FINDINGS AND OBSERVATIONS FROM THE RSE SITE VISIT
4.1 FINDINGS
The observations provided below are not intended to imply a deficiency in the work of the system
designers, system operators, or site managers but are offered as constructive suggestions in the best
interest of the EPA and the public. These observations obviously have the benefit of being formulated
based upon operational data unavailable to the original designers. Furthermore, it is likely that site
conditions and general knowledge of ground water remediation have changed over time.
4.2 SUBSURFACE PERFORMANCE AND RESPONSE
4.2.1 WATER LEVELS
Ground water levels are collected and interpreted with each monitoring event. The potentiometric
surface map presented in the January 2003 Ground Water Monitoring Report is included as Figure 4-1. It
shows what appears to be influence of both P&T systems on the regional ground water flow. For
example, the map shows that the regional gradient flattens in the MFA where extraction is occurring and
cones of depression near each of the LA extraction wells. The contours, however, are influenced by the
water elevations measured from operating extraction wells. Because extraction wells are subject to well
losses and have very localized drawdown due to pumping, water levels from these wells are not
necessarily indicative of the water level in the surrounding formation. As a result, if other water level
measurements are not made in the area, some of the contours may show excessive influence due to
pumping and perhaps an overestimated interpretation of plume capture. Specific examples of where the
contours may overestimate the influence of pumping are as follows:
The water level at active recovery RW-2 (280.06 ft) is used. In its absence, the 288 ft
contour may have been drawn much closer to MW-5 (287.97 ft) rather than MW-3
(288.54 ft), effectively eliminating the large trough in the potentiometric surface. The
cones of depression from RW-1 and RW-2 would then have appeared much more limited
as it is for RW-3 where the effect of pumping is almost unnoticeable at nearby well MW-
11.
The water levels at active recovery wells RW-101C, RW-108A, RW-303, and RW-404
are all used and other monitoring wells are not located in the immediate vicinity. As a
result, the 292 ft contour may be artificially shifted to the south with a trough that
suggests influence from pumping. In actuality, the trough and influence from pumping
may be significantly smaller.
The monitoring report also does not provide the extraction rates for the various wells. Although
extraction rates for the LA wells were originally 3 gpm each for a total of 9 gpm, the pumping has likely
changed. In 1996, the total extraction rate was estimated at 3.5 gpm, and during the RSE site visit the
flow totalizers for these wells revealed a total pumping rate of approximately 4.5 gpm, with RW-3 not
operating. To better resolve the influence of pumping on the regional hydraulic gradient, the pumping
rates should be provided along with the potentiometric surface maps, when possible.
Risdon RSE Report, April 11,2003 (Revised September 1, 2004) 15
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4.2.2 CAPTURE ZONES
A capture zone analysis with a numerical model and particle tracking was provided as part of the August
1999 Interim Corrective Measure Evaluation Report to help evaluate potential locations for additional
extraction wells. However, no other capture zone analyses have been conducted of the currently
operating P&T systems. The potentiometric surface maps provided in the ground water monitoring
reports may be used in an attempt to interpret capture if compared to the plume maps or target capture
zones; however, for the above stated reasons, the capture may be inconclusive or overestimated. The
provided potentiometric surface maps are also not sufficient to evaluate capture in the bedrock or in the
vertical direction.
The degree of capture in the MFA, LA, and at the northeastern property boundary are discussed below.
MFA
In the MFA, the pumping rate is generally below 1.5 gpm. With the following conservative parameters a
water budget or simplistic analytical capture zone calculation suggests that capture would require
pumping on the order of 5 gpm to 10 gpm, which is greater than the actual pumping rate.
hydraulic conductivity (K= 13 ft/day)
background gradient (/ = 0.02 ft/ft)
saturated thickness (b = 20 ft)
plume width (w = 200 ft)
factor of safety (generally between 1.5 and 2.0) to account for additional ground water
contributions from recharge, surface water, or underlying formations (F= 1.5)
Q=FxKxixbxwx (conversion factors)
LA
(7 48 gallons 1 day "\
Q = 1.5 x 13 (ft / day) x 0.02 (ft / ft) x 20 ft x 200 ft x , x = 8.1 gpm
v yj ^ ' V ft3 1440 minutes; 5F
Because the LA extraction wells are only operating at half of their intended rate (approximately 4.5 gpm
rather than 9 gpm), capture may be compromised in the LA. The above analytical calculation, which is
also applicable to the LA, suggests that the reduced pumping rate is nearly equivalent to the low-end
approximation of what may be needed. Downgradient wells MW-10, MW-14, and MW-15 have shown
decreasing concentrations, suggesting that plume migration has been somewhat mitigated. However, it is
unclear if pumping at the current rate will continue to limit migration as effectively.
Northeastern Boundary
EPA, the facility, and the RSE team agree that capture is not provided along the northeastern border of
the property where some of the highest VOC concentrations have been measured (e.g., near well MW-
111 and MW-508C). In the Interim Corrective Measure Evaluation Report (Woodard and Curran,
1999), the facility and its contractors suggested the installation of two additional pumping wells to
provide containment of the plume at the property boundary. However, those wells have not been
installed to date because the site team as a whole has focused on other site-related issues, including
characterization of offsite ground water and soil vapor contamination.
Risdon RSE Report, April 11,2003 (Revised September 1, 2004) 16
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4.2.3
CONTAMINANT LEVELS
Ground water monitoring was not performed regularly since 1996, but ground water sampling and
analysis was restarted with a sampling event in September 2001 in which 25 of the 36 wells were
sampled. The sampling program included wells on or within 300 feet of the site. Annual sampling for
VOCs is now conducted at 13 wells. The following table reports the 1996, 2001, and 2002
concentrations of the more prevalent VOCs at 11 of the 13 wells that are included in the monitoring plan.
Monitoring
Well
MW-3
MW-9
MW-10
MW-11
MW-14
MW-15
MW-111
MW-112
MW-508
MW-508C
MW-601B
General Location
LA
LA
West of LA
North of LA
North of LA
(offsite)
North of LA &
MFA (offsite)
Northeast
boundary
Between LA &
MFA
Northeast
boundary
Northeast
boundary
(bedrock)
Northeast
boundary
Year
Sampled
1996
2001
2002
1996
2001
2002
1996
2001
2002
1996
2001
2002
1996
2001
2002
1996
2001
2002
1996
2001
2002
1996
2001
2002
1996
2001
2002
1996
2001
2002
1996
2001
2002
1,1 DCE
(1 ug/L)*
166
320
170
1,322
17,000
NS
ND
300
10
227
370
340
31
ND
ND
240
20
ND
1,870
<1000
<200
680
<500
<250
209
<50
<10
N/A
820
<1000
N/A
380
330
1,1,1 TCA
(20,400 ug/L)*
516
1,200
900
80,756
58,000
NS
56
960
17
2,574
1,100
910
80
10
9.7
851
60
32
10,126
2,800
870
1,640
<500
<250
ND
<50
19
N/A
660
<1000
N/A
1,100
1,200
PCE
(88 ug/L)*
ND
ND
ND
ND
ND
NS
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
1,264
1,900
920
360
<500
<250
ND
<50
<10
N/A
<500
<1000
N/A
1,000
850
TCE
(219 ug/L)*
10,840
13,000
15,000
1,789
4,500
NS
14
180
6.6
2,675
1,900
1,800
82
11
7.9
11,252
1,300
1,200
269,385
60,000
25,000
4,519
26,000
14,000
9,237
2,000
970
N/A
23,000
34,000
N/A
3,100
3,000
* Represents the most stringent applicable Connecticut remediation standard (see Section 3.1)
Risdon RSE Report, April 11, 2003 (Revised September 1, 2004)
17
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In general, concentrations within the LA source area (MW-3 and MW-9) or within the influence of the
LA recovery wells (MW-11) are not decreasing. However, concentrations in wells downgradient of the
LA recovery wells (MW-10, MW-14, and MW-15) are decreasing, indicating that contaminant migration
has been somewhat mitigated by these wells.
Concentration data are not available within the MFA, but concentration data are available along the
northeastern (downgradient) property boundary. Concentrations at MW-111 and MW-508 are
decreasing, but the concentrations in other wells appear to have no discernible trend. Persistent TCE
contamination two orders of magnitude above the most stringent applicable TCE standard of 219 ug/L
has been found in bedrock (MW-508C), 20 feet below MW-508. This indicates that not only is
contamination migrating offsite in the overburden, it is migrating offsite in the bedrock. Furthermore,
these TCE concentrations of over 11,000 ug/L are indicative of DNAPL.
Off-property sampling associated with the off-property vapor study in 2002 indicates VOC
contamination above the most stringent applicable standards 500 feet to the northeast (GW-1A,B,C and
MW-1) beyond the Medsource facility and immediately adjacent to a residence on Old Newtown Road
(GW-2A,B). The horizontal and vertical extent of offsite contamination cannot be determined from
current or previous sampling events.
With regard to the inorganic contaminants, copper, nickel, and zinc have been found along the
northeastern boundary of the property at stable concentrations well above the surface water protection
criteria. There are no inorganics sampling results from locations downgradient to complete delineation
of these compounds. Cyanide has been repeatedly detected above 0.13 mg/L at MW-15, the only well
located downgradient of the site sampled for inorganics. This compares to the surface water protection
criteria of 0.052 mg/L.
4.3 COMPONENT PERFORMANCE
The P&T systems in both the MFA and the LA and the SVE system in the MFA are maintained by the
plant operator. Although they are attended to on a daily basis, regular monitoring was not conducted, or
documentation of that monitoring is not available. Therefore, the effectiveness or efficiency is not
readily discernible since 1996 when more detailed records were available.
4.3.1 EXTRACTION SYSTEM WELLS, PUMPS, AND HEADER
LA System
The LA ground water system operates 24 hrs/day continuously except for the winter holiday and mid-
summer shutdowns, which are approximately two weeks each. The most recent data (from 1996)
indicates the system influent averaged about 3.5 gpm (all 3 wells combined pumping 24 hrs/day). A
check of the system flow rate during the RSE visit indicated that the flow rate was about 3 to 5 gpm.
During the RSE site visit totalizers on each well were observed over a several minute period. RW-1 was
observed to be pumping continuously at approximately 1 gpm, RW-2 was observed to pump continuously
at about 3.5 gpm, and RW-3 was pumping little if any water.
The pumps have never been replaced, but foot valves have been replaced on occasion.
Risdon RSE Report, April 11,2003 (Revised September 1, 2004) 18
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MFA System
The combined flow rate from the extraction wells in 1996 was reported at about 1.3 gpm. The system
operates only during plant operating hours (8 to 16 hrs/day, 5 days/week) so the actual flow rate is about
500 to l,100gpd.
4.3.2 AIR STRIPPER
LA System
The most recent data (from 1996) indicates the system influent averaged about 15 mg/1 total VOCs (0.6
Ibs/day). Effluent VOCs were below 0.5 mg/1 in 7 of the 9 analyses reported in the 1996 Annual Report.
The air stripper packing is currently cleaned about once per year with nitric acid. The stripper packing
has not been inspected recently, and it is likely that the acid washing is no longer completely effective
and the stripper efficiency has decreased. The stripper influent VOC concentrations have not been
analyzed recently. An annual stripper effluent sample is reportedly taken (recent data was not provided)
and semiannual combined POTW discharge samples are taken. The samples reportedly pass applicable
standards.
MFA System
For ground water, data from 1996 indicates influent total VOCs at 0.4 to 4.5 mg/1 ( <0.1 Ibs/day of VOC
mass) and effluent total VOCs < 0.05 mg/1 in 9 of 10 samples. VOC treatment efficiency was typically
about 99.0%. The MFA ground water system influent metals concentrations were not provided, and no
monitoring wells are located in the immediate vicinity of the MFA source area.
For the SVE system, VOC mass removal from the SVE system was 1 to 2 Ibs/day in 1996. Current
recovery data is not available.
4.3.3 EFFLUENT/DISCHARGE
All effluent is blended with treated water from the facility wastewater treatment plant before discharge to
the POTW. The facility wastewater treatment plant is reportedly operating at capacity. Although it was
included in the tour of the site, its effectiveness is not reviewed as part of this RSE.
The Risdon facility does require water for their operations; however, due to the high iron and calcium
content of the extracted water, treated water cannot be used for the production processes.
4.3.4 SYSTEM CONTROLS
LA
Extraction pumps and transfer pumps operate based on level controls. The design drawings indicate that
extraction wells are shut off based on high-high transfer tank level or low blower pressure. The facility
is manned by security while the system is operating and a system operator is on call.
MFA
The system only operates during plant hours and is maintained by the plant operator as part of the
wastewater treatment plant.
Risdon RSE Report, April 11,2003 (Revised September 1, 2004) 19
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4.4
COMPONENTS OR PROCESSES THAT ACCOUNT FOR MAJORITY OF
COSTS
Annual costs for operating the environmental remedies and monitoring ground water are approximately
$60,000 per year. A breakdown of this annual cost is provided in the following table based on estimates
provided by the facility and its contractor. These costs do not include costs associated with additional
studies such as the on and off-property soil vapor intrusion studies.
Item Description
Labor: Project management and technical support
Labor: Plant operator
Ground water monitoring (forecasted sampling and analysis)
Utilities: Electricity
Well/Pump Maintenance
Non-utility consumables (GAC, chemicals, other materials or parts)
Chemical Analysis (process monitoring)
Discharge fees and waste disposal (POTW)
Total Estimated Cost
Estimated Cost
$25,000
$10,000
$5,000
$9,200
$2,800
$500
$500
$7,500
$60,500
4.4.1
UTILITIES
The utility costs provided are for the electricity required to operate the extraction-well pumps, ground
water treatment systems, and MFA SVE system. Additional electrical costs are required for operation of
the facility wastewater treatment plant, but this is not included.
4.4.2
NON-UTILITY CONSUMABLES AND DISPOSAL COSTS
Only the vapor phase GAC used for the MFA P&T system is included. Chemical costs associated with
the pH neutralization and LA air stripper acid washes are not included.
4.4.3
LABOR
The plant operator is on salary for operating the facility wastewater treatment system. His
responsibilities include maintenance of the two P&T systems and the SVE system. The $10,000 included
in the above table represents a portion of the salary estimated by the facility.
4.4.4
OTHER COSTS
The ground water sampling and analysis cost of $5,000 provided in the table is for the forecasted
monitoring program (i.e., for 2003 and beyond). The cost of $5,000 was estimated based on the cost for
the 2002 sampling program that was provided during the RSE site visit. The forecasted monitoring
includes annual sampling and analysis of VOCs at 13 locations and metals at 10 locations (most of which
overlap with the 13 VOC locations). This forecasted monitoring program marks a decrease from the
2002 monitoring program as discussed in Section 2.4 of this report. The 2002 ground water monitoring
program cost was approximated as $15,000 and included the same VOC sampling and analysis, but also
included quarterly (rather than annual) sampling for metals.
Risdon RSE Report, April 11, 2003 (Revised September 1, 2004)
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4.5 RECURRING PROBLEMS OR ISSUES
The most prevalent recurring problems or issues with remedy operation pertain to the LA P&T system,
because it is isolated from the other site systems and checked less frequently. Sedimentation has
reportedly reduced the depth to bottom of some of the wells. In addition, fouling or other problems may
be contributing to reduced extraction rates. During the RSE, RW-3 appeared to not be pumping. The
flow totalizers suggested a total flow rate of approximately 5 gpm. The operator was not aware of this
apparent decrease. The LA air stripper also is likely fouled beyond the potential for cleaning. However,
the efficiency of the unit is difficult to determine due to a lack of influent and effluent sampling.
With regard to ground water sampling, the primary problem is that access to MW-9 is frequently limited
by parked cars, which block the well despite the use of traffic cones to keep it clear. Although not
necessarily a recurring issue, the RSE and site team identified that the cap for MW-12 had previously
been destroyed, most likely by the snow plow, and was open to the atmosphere.
4.6 REGULATORY COMPLIANCE
The plant reportedly meets all discharge requirements. Although influent and effluent sampling is not
conducted routinely, historical data suggest the mass removed by the P&T and SVE systems are likely
well below the reported annual limit of 15 tons per year.
4.7 TREATMENT PROCESS EXCURSIONS AND UPSETS, ACCIDENTAL
CONTAMINANT/REAGENT RELEASES
No releases or accidents were reported during the site visit.
4.8 SAFETY RECORD
No reportable incidents were indicated by the facility or contractor during the site visit.
Risdon RSE Report, April 11,2003 (Revised September 1, 2004) 21
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5.0 EFFECTIVENESS OF THE SYSTEM TO PROTECT HUMAN
HEALTH AND THE ENVIRONMENT
5.1 GROUND WATER
Because ground water has a GB classification and there is a lack of potable wells in the vicinity, the
primary avenues of exposure to ground water are due to volatilization of VOCs and discharge of
contaminants to the Still River.
Residential and commercial/industrial properties downgradient have ground water concentrations
exceeding applicable volatilization criteria. Of particular concern is the elevated VOC concentrations in
the ground water near a residence on Old Newtown Road, which has a basement. Also of potential
concern are the commercial buildings in the area without basements, including the Risdon office space,
which directly overlies the highest recorded concentrations of site-related VOCs.
Ground water exceeding the surface water protection criteria for TCE was found in the overburden
approximately 500 feet offsite in grab samples at GW-1A, GW-1B, and GW-2A. Given that
contamination has been found in bedrock at MW-508C on site, it is probable that contamination above
standards is present in bedrock offsite.
Furthermore, it is apparent that contaminated ground water continues to migrate off the Risdon site as the
ground water extraction system is insufficient to provide hydraulic containment, particularly at the
northeastern boundary of the site.
5.2 SURFACE WATER
The current data are insufficient to determine if surface water (Still River or wetlands) is being impacted
by VOCs and/or inorganics, since no surface water sample results were provided to the RSE team and the
offsite VOC plume and inorganic impact have not fully been delineated.
5.3 AIR
Residential and commercial/industrial properties downgradient have ground water concentrations
exceeding applicable volatilization criteria. The data are insufficient to determine if humans are being
impacted by VOC's, since no vapor samples from inside structures were provided to the RSE team. The
CT Department of Public Health has suggested testing of the indoor air at the two residences near the site
due to the high potential for vapor intrusion. Further efforts are also needed to determine if indoor air is
compromised at the commercial properties, including the Risdon facility. An indoor air sampling event
has been planned for late March 2003.
Risdon RSE Report, April 11, 2003 (Revised September 1, 2004) 22
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5.4 SOILS
Potential exposure pathways to contaminated soil were not explicitly reviewed by the RSE team.
However, the site team indicated the greatest potential exposure to contaminated soil would be through
construction that requires digging or work on subsurface utilities. In such cases, the air quality due to
VOCs would be a primary concern rather than soil ingestion and dermal absorption. Based on
discussions during the RSE site visit, no institutional controls are in place to prevent such exposures.
5.5 WETLANDS AND SEDIMENTS
The data are insufficient to determine if sediments in the Still River or if the wetland downgradient of the
site are being impacted by VOCs. No sediment sample results were provided to the RSE team.
Risdon RSE Report, April 11, 2003 (Revised September 1, 2004) 23
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6.0 RECOMMENDATIONS
Cost estimates provided herein have levels of certainty comparable to those done for CERCLA
Feasibility Studies (-307+50%), and these cost estimates have been prepared in a manner consistent with
EPA 540-R-00-002, A Guide to Developing and Documenting Cost Estimates During the Feasibility
Study, July 2000.
The following sections provided recommendations in four categories. The recommendations are
generally presented such that the more critical recommendations in each category appear first. Section
6.5 provides a suggested approach to implementation that more clearly prioritizes the recommendations.
6.1 RECOMMENDATIONS TO IMPROVE EFFECTIVENESS
6.1.1 PERFORM VAPOR SAMPLING WITHIN BUILDINGS, INSTALL VENTING SYSTEMS As
APPROPRIATE
The June 2002 Health Consultation Report recommends sampling the 2 residences because the ground
water and soil gas concentrations at both indicate indoor air could be above chronic comparison values.
It does not specifically recommend sampling the 3 commercial/industrial locations unless significant
cracking of the slab or other structural defects are evident. Sampling at some of the commercial
properties can be delayed and made contingent on the results of the residential sampling; however, the
reduction in cost does not necessarily scale with the number of samples and making two trips would
likely be more costly than one single trip. Sampling of air in the Risdon facility should also be
considered. Facility uses of TCE and other chlorinated solvents may complicate this sampling, but
sampling in the office spaces may be merited, particularly given the high soil vapor concentrations
beneath that area.
A work plan should be simple, including proposed locations and use of a PID for screening inside. If
VOCs are found above comparison values in indoor air, a venting system should be installed. If not,
monitoring should continue at the residences and possibly the other locations on a quarterly basis for a
year, and annually thereafter as long as high ground water levels are still present. For budgeting
purposes, the annual cost for continued sampling at these locations over the upcoming years is assumed
at $5,000 per year.
A work plan for sampling was completed by the site contractor and reviewed by EPA. Because the EPA
review of this document coincided with the time frame of this RSE report, the work plan was not
reviewed by the RSE team. In its comments on the draft RSE report, the facility indicated that sampling
would only be conducted at the two residences and that ground water and soil vapor sampling would be
conducted in addition to indoor air samples to include in the assessment of vapor intrusion. The cost of
the effort was not provided.
6.1.2 DEVELOP AND IMPLEMENT INSTITUTIONAL CONTROLS
The site team should work with the local Department of Power and Water and the board of health to
implement institutional controls, both onsite and offsite. These controls should clearly outline the
estimated plume area. In addition, they should prevent the use of ground water without treatment within
Risdon RSE Report, April 11, 2003 (Revised September 1, 2004) 24
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the plume area and should outline specific health and safety measures to be taken by construction or
subsurface utility workers that are working within the plume area.
The cost to develop these institutional controls may range from $5,000 to $20,000, including meetings
and document preparation.
6.1.3 ADD EXTRACTION WELLS TO PROVIDE HYDRAULIC CONTAINMENT NEAR THE
PROPERTY BOUNDARY
Additional ground water extraction is recommended to address continued offsite contaminant migration
along the northeastern property boundary and "stabilize" the site. Implementing this recommendation
should be a priority short-term goal. Although this additional pumping alone would not necessarily
satisfy the ground water El, it is a crucial step because it provides a degree of plume control and it
prevents further offsite migration that is more difficult to address. Additional pumping or remedial
action at offsite locations can be addressed as part of more intermediate goals.
This recommended ground water extraction should serve the following purposes:
It should work in concert with pumping from the LA to prevent offsite migration of
contamination in both the overburden and the bedrock (i.e., stabilize the site).
It should provide a zone of capture that, if possible, does not include receptors. That is,
the extraction wells should be located such that contamination is not pulled near
potential receptors at levels that pose an unacceptable risk.
The August 1999 Interim Corrective Measure Evaluation Report proposed locations for two extraction
wells based on ground water modeling and particle tracking. EW-4 would be located between the LA
and the MFA near MW-112 and would pump at approximately 3 gpm from both the overburden and
weathered bedrock and EW-5 would pump at approximately 5 gpm from near the MW-601 cluster.
Although these two extraction wells are appropriately located for two crucial areas of contamination,
they do not address the bedrock contamination in MW-508C. Therefore, a bedrock extraction well
located near MW-508C is also recommended. Based on the extraction rates at the other proposed
extraction wells, an appropriate extraction rate for the third new well may be between 3 and 5 gpm.
Figure 6-1 depicts the proposed locations for the three new extraction wells. All three new wells should
be screened across overburden and bedrock from about 10 feet bgs to the bottom of the well.
A calculation presented in Section 4.2.2 of this report suggests that pumping on the order of 5 gpm on the
low-end may be appropriate for a capture zone 200 feet in width. Together, the three new pumping wells
are estimated to pump over 10 gpm.
Submersible pumps should be used at the new wells because they allow for drawdown beyond ~27 feet
(-80% of a perfect vacuum), which is the maximum the aboveground pumps can draw. The extra
drawdown may or may not be necessary but in case it is, submersible pumps can provide it for a cost
similar to aboveground pumps. The facility might also potentially save cost on smaller vault construction
by using submersible pumps.
Once installed, the new extraction wells should be pump tested for approximately 24 hours. The results
of pump tests should be interpreted to determine the yield and estimate hydraulic conductivity. If these
estimates are not as expected additional extraction wells may be considered. Measurement of water
levels and pumping influence should occur in both the overburden and bedrock (including MW-508C) so
that capture of contamination can be evaluated in both formations. Sampling for VOCs and metals
Risdon RSEReport, April 11, 2003 (Revised September 1, 2004) 25
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should also be conducted during the pump test (during the initial pumping and near the end of pumping)
to provide an indication of concentrations under pumping conditions. This is pertinent given that
concentrations in extraction wells are often lower than monitoring wells and use of monitoring well
concentrations could lead to over-design of a modified treatment system.
Once the extraction wells are operating continuously, their effectiveness at providing containment can be
determined by interpreting potentiometric surface maps, analyzing capture with an updated ground water
model (see Section 6.1.8), and monitoring changes in constituent concentrations downgradient of the
expected capture zone. The current ground water monitoring program (annual water quality sampling
and quarterly water level measurements) likely provides sufficient data to conduct these analyses and
update the ground water model. Therefore, an increase in the sampling frequency from monitoring wells
is likely not necessary. Sampling of the blended treatment system influent, however, should be
conducted and reported as discussed in Section 6.3.1.
The cost for well installation is estimated at approximately $36,000, including well heads and pumps.
This assumes 3 wells that are on average 40 feet deep. The well near MW-508C may be deeper
(approximately 50 feet), but EW-4 may be shallower (approximately 30 feet in depth). The pump tests
for the three wells, including the water disposal, interpretation, and laboratory analysis could likely be
done for approximately $25,000.
6.1.4 INSPECT AND REHABILITATE WELLS AND PIPING FOR THE LA EXTRACTION SYSTEM
The LA extraction wells were originally intended to pump 3 gpm each for a total extraction rate of 9 gpm
in the LA. However, measured extraction rates are lower. In 1996, the total extraction rate was
measured at 3.5 gpm, and during the RSE site visit the flow totalizers suggested a total extraction rate of
4.5 gpm, with RW-3 not pumping. Decreases in concentrations at MW-10, MW-14, and MW-15 suggest
that pumping has historically provided a degree of capture, but current pumping may not provide
complete capture. The model simulations presented in the August 1999 Interim Corrective Measure
Evaluation Report assumed RW-1, RW-2, and RW-3 were each pumping 3 gpm. These simulations
suggested capture would be complete in the LA with a total extraction rate of 9 gpm.
These wells should be inspected and rehabilitated or replaced as necessary. The wells should be
investigated for sedimentation that may have reduced the length of the screened interval, and the wells
and the piping should be inspected for biofouling. The level of effort for the inspection and
rehabilitation/replacement is difficult to estimate and depends on what the inspection reveals. The RSE
team estimates approximately $15,000 for this task, which includes the inspection, chemical treatment,
and replacement of some piping. It does not account for re-drilling any of the wells. The goal is to
restore the LA extraction system capacity back to 9 gpm. Depending on the causes that are identified, a
we 11-maintenance program may be advisable.
6.1.5 REPLACE EXISTING TWO TREATMENT SYSTEMS WITH ONE NEW SYSTEM CAPABLE
OF TREATING A HIGHER FLOWRATE
The extracted ground water from the LA, MFA, and new extraction wells should be treated by a single,
automated treatment system with a low-profile air stripper (tray aerator) that would likely be located in
the current MFA treatment area. The air stripper should be capable of handling up to 50 gpm (to allow
for system expansion) and the expected influent concentrations, which should be estimated based on the
blended influent from the LA and MFA (samples are needed) combined with the blended influent of the
new wells estimated from the pump tests. Vapor phase GAC (two 1000-pound units arranged in series)
will likely be needed for treatment of the air stripper offgas. Based on the metals concentrations seen in
Risdon RSE Report, April 11, 2003 (Revised September 1, 2004) 26
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monitoring wells and the discharge standards, metals treatment will not likely be necessary. Adjustment
of pH can occur as part of this system or in a separate system.
Discharge of treated water can either be to the POTW or to surface water. Current POTW costs are
approximately $7,500 for approximately 5 gpm. The estimated total extraction rate would be
approximately 20 gpm to 25 gpm. Therefore, under the same permit, the POTW cost may be as high as
$30,000 to $37,500 per year. Alternatively, an NPDES permit for discharge to surface water could be
obtained for capital costs of approximately $10,000 for the application and testing and approximately
$12,000 per year in sampling and analytical costs. Therefore, with the current information, discharge to
surface water appears more cost effective and the associated capital costs are included in the cost
estimate for this recommendation. Savings in piping costs may be possible if piping can run inside the
facility.
Item Description
Trenching, piping, electrical, controls from LA to MFA
(800feetat$100/foot)
Trenching piping, electrical, controls from new wells to MFA
(up to 1,500 feet at $100/foot)
Air stripper with controls (installed)
Two 1000-pound GAC units (installed)
pH adjustment (tank, controller, probe, metering pump, piping)
NPDES permit application and testing
Engineering (-20%)
Contingency (-20%)
Total Estimated Cost
Estimated Cost
$150,000
$50,000
$10,000
$15,000
$10,000
$63,000
$75,000
$453,000
Although more water will be treated, the annual electrical costs are not expected to increase significantly
because treatment will be accomplished in one location by a more efficient air stripper. Materials usage,
for pH adjustment and off-gas treatment will likely increase by approximately $1,000, but the actual
increase is difficult to quantify without more knowledge of the expected influent concentrations.
Operator labor is expected to remain the same.
6.1.6
UPDATE THE SITE CONCEPTUAL MODEL
The site team should update the site conceptual model (not a numerical model) that documents
contaminant sources, contaminant fate and transport mechanisms, and potential receptors. The
conceptual model can then be used to identify data gaps, can be updated based on new data, and can
serve as the basis for establishing short, intermediate, and long-term goals. The updated conceptual
model, the goals, and the progress toward those goals should be included in future progress reports.
Establishing goals is discussed in Section 6.4 as part of a site exit strategy.
The conceptual model should account for the persistent and elevated VOC concentrations that are
indicative of DNAPL. Given the currently accessible data, it is reasonable to assume that there is a
continuing source of dissolved phase contamination in the LA source area and in the MFA, and possibly
migrating downgradient along the top of bedrock or through bedrock toward the northeastern property
boundary.
Risdon RSE Report, April 11, 2003 (Revised September 1, 2004)
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It should also account for dissolved ground water contamination migrating offsite and to what degree this
migration is limited or has been limited by pumping in the LA. Furthermore, MW-508C indicates the
presence of elevated concentrations in bedrock that have migrated a few hundred feet from the source
area in the MFA. Such migration could continue through bedrock. The degree to which additional
pumping along the northeastern property boundary will address this deep contamination should be
addressed. Another aspect to be considered is the degradation of 1,1,1-TCA to 1,1-DCE. Although
1,1,1-TCA concentrations in many locations are below standards, this chemical degrades into 1,1-DCE,
which has much stricter standards, including a residential volatilization criteria of 1 ug/L. Elevated
concentrations of 1,1 DCE are already evident in multiple wells.
The various potential receptors (i.e., indoor air and surface water) should also be considered. For
example, once indoor air is addressed at the residence on Old Newtown Road, impacts to the Still River
should be considered, especially since the river is less than 100 feet further downgradient of the
residence.
The site remedy, including the addition of extraction wells, should be consistent with the site conceptual
model. The documentation of this site conceptual model should occur in the annual reports (see
Recommendation 6.3.1). Approximately $5,000 beyond the cost of the first annual report may be needed
for an initial update to the site conceptual model.
6.1.7 RECONFIGURE SVE SYSTEM (ADD NEW SVE WELLS IN SELECTED AREAS)
The June 2002 On-Property Soil Vapor Survey Report indicated: 1) elevated vapor concentrations along
the northeastern portion of the facility and also in the MFA; and 2) a rebound effect in the MFA when
the SVE system is shut down. Although the soil vapors in the MFA are addressed by the current SVE
wells, vapors below office space to the northeast are not. SVE has a positive affect on soil vapor
concentrations. As a result, the SVE system should be augmented with additional extraction points along
the northeastern portion of the property. The RSE team suggests the addition of approximately 8 new
wells to a depth of 15 feet. The RSE team estimates that the well installation and associated piping could
be done for approximately $30,000. With the additional mass recovery, vapor GAC will likely be
required for treatment of the recovered vapor.
To minimize disruption to the office space and factory, the wells might be located just outside of the
facility toward Old Newtown Road. Running the pipe for these wells (or even the extraction wells
recommended in Section 6.1.3) to the treatment area in the MFA might result in cutting of the plant floor.
This would likely pose a health and safety issue due to high soil vapor concentrations. Therefore,
appropriate measures should be taken or alternative routes for laying the pipe should be considered.
Currently, for many of the recovery wells (both SVE and P&T) within the MFA, piping is run above
ground along the facility walls and ceiling.
6.1.8 UPDATE/VALIDATE GROUND WATER FLOW MODEL AFTER NEW EXTRACTION
WELLS ARE ON-LINE
A well-calibrated ground water flow model is a useful tool for evaluating the effectiveness of a remedy
because it considers pumping rates, estimated hydraulic conductivities, recharge, measured water
elevations, and known geological information (e.g., depth to bedrock). For capture zone analyses, it can
be used (along with particle tracking) to outline the interpreted capture zone. The model should be able
to reasonably match measured water levels for various pumping scenarios. Therefore, the model should
be calibrated to the water levels collected during the current pumping scenario as well as to the water
levels that are collected after the new extraction wells have been installed. It is crucial, however, to have
accurate information, such as the flow rates. Therefore, when the model is calibrated to water levels
Risdon RSE Report, April 11, 2003 (Revised September 1, 2004) 28
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under current pumping conditions, it should account for the actual flow rate, which appears to be
approximately 4.5 gpm rather than the presumed 9 gpm. The RSE team feels that the new extraction
wells should be installed and on-line (a high priority) prior to updating the model.
Once the model is calibrated to multiple pumping scenarios, it should be used to evaluate capture and site
stabilization. At a later time, a contaminant transport model can potentially be developed to simulate
contaminant concentrations both within the containment zone and beyond the containment zone. Ground
water modeling of contaminant transport may be useful in evaluating the risks of the downgradient
offsite plume to various potential receptors and to guide the site team in choosing an appropriate remedy
for the offsite contamination.
The modeling report that describes the calibration of the ground water model and the use of the ground
water model for capture zone analyses or remedy evaluations should include or reference the following
basic information:
rationale for horizontal and vertical discretization and boundary conditions
parameter values used and the basis for those values (i.e., hydraulic conductivity
distribution, recharge, pumping
model calibration simulations including the measured vs. simulated water levels, at
multiple locations, for various pumping combinations
simulation results for scenarios, and an assessment of how the results might change if
different parameter values were assigned
This flow modeling effort is approximated to cost $20,000.
6.1.9 PERFORM OFFSITE PLUME DELINEATION
Ground water contamination has been found above the most stringent applicable standards over 500 feet
from the site (GAR-MW-1 and GW-1 cluster). In addition, TCE contamination orders of magnitude
above standards has been found in bedrock approximately 20 feet below the majority of the site
monitoring wells. This bedrock contamination has not been delineated vertically or horizontally. Given
that bedrock contamination has been found in MW-508C, a few hundred feet from the MFA or LA
source areas, it is likely that this contamination has either migrated further or has the potential to migrate
further.
The ground water contamination above the most stringent applicable standards should be delineated
horizontally and vertically offsite. To the extent possible, monitoring wells from other properties can be
used. For example, MS-MW-4 appears similar in location to the GW-1 cluster where contamination was
previously found and the GAR-MW-1 well was sampled as part of the off-property air quality study.
There are other areas, however, that also should have wells installed. For example, ground water at the
residence on Old Newtown Road has been found to exceed standards in direct-push samples. A
permanent monitoring well would be useful on this property because it is proximate to two potential
receptors, the residence (indoor air) and the Still River, less than 100 feet away.
Two monitoring wells were proposed in the August 1999 Interim Corrective Measure Evaluation Report.
One of those wells, MW-701 (not shown), is similar in location to some of the Medsource wells (MS-
MW-5 and MS-MW-6) and may not be necessary, if those Medsource wells can be sampled. The other
well, MW-702 (not shown), however, is a bedrock well adjacent to MW-15 and will likely yield valuable
Risdon RSE Report, April 11, 2003 (Revised September 1, 2004) 29
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information with regard to the extent of the bedrock contamination found in MW-508C. The majority of
the existing offsite monitoring wells are depicted in Figure 1-3.
If monitoring wells from adjacent properties can be sampled as part of the delineation effort, the RSE
team estimates the need for approximately 2 additional shallow wells and up to 5 bedrock wells.
However, if these additional wells cannot be used, the RSE team estimates the need for up to 10 soil
borings, approximately 5 shallow wells, and up to 5 bedrock wells.
The following cost estimate pertains to the more optimistic option of using existing wells on nearby
properties.
Item Description
Installation of 2 shallow monitoring wells
Installation of up to 5 bedrock wells (over 40 ft deep)
Survey
Sampling of approximately 15 offsite wells (two rounds, one to
coincide with annual sampling event) for VOCs and inorganics
Total Estimated Cost
Estimated Cost
$8,000
$25,000
$1,000
$22,000
$56,000
It is likely that some of the offsite wells would be added to the annual sampling program for VOCs. In
addition, a final remedy that addresses the offsite plume will likely be required. The scope of this
remedy is difficult to determine prior to the investigation. The remedy may range from "remedy by
monitoring" supplemented with model simulations demonstrating plume stabilization and acceptably low
risks to potential receptors to high-intensity targeted (HIT) events in select locations to the installation
and operation of offsite extraction wells. The potential future costs of monitoring and an appropriate
remedy are not included in this estimate but should be revisited by the site team once the recommended
investigation is complete.
6.2
RECOMMENDATIONS TO REDUCE COSTS
No specific recommendations were found to reduce the costs of current operation. The recommendations
to improve effectiveness, improve technical operation, and gain site closure are intended to provide cost-
effective solutions that are protective of human health and the environment. For example, the RSE team
believes that installing and operating one effective treatment system, as suggested in Recommendation
6.1.6, is more cost-effective than installing and operating multiple treatment systems. In addition, clearly
outlining site goals, as discussed in Recommendation 6.4.1, will help optimize the use of resources and
limit site activities to those essential to meet the site goals.
6.3
MODIFICATIONS INTENDED FOR TECHNICAL IMPROVEMENT
6.3.1
INSTITUTE QUARTERLY AND ANNUAL OPERATIONS REPORTS
The P&T and SVE systems are integral to the site remedy and their performance should be routinely
evaluated and documented in quarterly and annual reports. Evaluation should include routine reading of
system parameters as well as regular influent and effluent sampling and comparison of these readings to
expected values and permit limits as applicable. This information should be available to the
Risdon RSE Report, April 11, 2003 (Revised September 1, 2004)
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environmental consultants for their review so that ground water conditions can be compared to the status
and performance of the extraction and treatment systems. Rather than submitting an additional report to
the already submitted quarterly ground water monitoring reports, the operations and ground water data
can be included in a single ground water and O&M quarterly monitoring report that includes the
following:
summary of major issues
weekly flow rates (by well and total)
quarterly influent and effluent water concentrations
monthly influent and effluent off-gas and SVE concentrations using a PID
mass removal calculations
daily operator logs
quarterly water levels on a figure (with interpreted potentiometric surface)
maintenance summary
action items
The estimated cost is $7,500 per quarter ($30,000 per year) and includes the report and laboratory
analyses for the process monitoring. An increase in operator labor to collect samples and record
measurements may be expected, but this should be more than offset by the labor savings from
implementing the treatment system described in Section 6.1.5.
The annual reports would summarize the quarterly reports but would also include the ground water
monitoring results and an evaluation of the remedy relative to its goals:
summary of system performance relative to goals and expected performance
updates to site conceptual model and exit strategy
contaminant concentrations at monitoring wells (annual sampling at approximately 25
new and existing select wells for VOCs and key inorganics)
system influent trend analysis including graphs and figures
a discussion of ground water hydraulic containment, trends in the plume, and cleanup
progress
surface water and/or vapor sampling results and trends
An annual report is expected to cost approximately $20,000. The ground water sampling and analysis,
including offsite wells, is expected to cost approximately $15,000 per year based on unit costs consistent
with the current ground water monitoring. Therefore, the total cost for all ground water and process
water monitoring and reporting is approximately $65,000 per year. Given that the costs for ground water
and process water sampling provided in the table in Section 4.4 is approximately $5,500, the net increase
in annual costs for this recommendation, relative to the costs in the Section 4.4 table, is approximately
$59,500.
6.3.2 REPAIR SURFACE CAP FOR MW-12
During the RSE site visit, the surface cap for MW-12 was observed to be destroyed (probably by snow
plow), and the flush-mounted monitoring well was open to air. This cap should be replaced. Costs are
negligible relative to the costs of the other recommendations.
Risdon RSE Report, April 11,2003 (Revised September 1, 2004) 31
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6.4 CONSIDERATIONS FOR GAINING SITE CLOSE OUT
6.4.1 DEVELOP AN EXIT STRATEGY
The site team should develop a clear plan or exit strategy for remediation at this site. Although the site
will not be ready for closure for a number of years, the plan for reaching closure should be established.
Addressing crucial items such as controlling potential human exposures and stabilizing the plume should
be given first priority, and delineating and remediating offsite contamination should follow. An exit
strategy should do the following:
identify all of the major environmental issues associated with the site
prioritize those issues
set goals for achieving those issues with specific conditions that make it clear when those
goals are achieved (including the discontinuation of active remediation)
provide measurable intermediate milestones to denote progress toward achieving those
goals
This exit strategy will facilitate communication between the facility, EPA, and CTDEP and help the site
team prioritize the site issues and address them in a timely manner. The RSE report summarizes some
potential options for short-term, intermediate-term, and long-term goals to serve as discussion points for
the site team. Actual site-specific goals should be developed by the site team. The RSE report
emphasizes that the following options for goals are relatively broad and a complete exit strategy requires
additional detail as mentioned in the above bullet list. The estimated cost for developing a site exit
strategy is approximately $20,000, including one set of revisions and discussions with EPA and CTDEP.
Example Short-term Goals
General time frame: to be accomplished as soon as possible (goal should be the end of 2003).
sample indoor air at surrounding residences and commercial buildings (including the
Risdon facility) and implement venting systems as necessary (Recommendation 6.1.1)
develop and implement institutional controls (Recommendation 6.1.2)
install additional on-site extraction wells to contain ground water contamination at the
site boundary and prevent further offsite migration in both overburden and bedrock
(6.1.3)
inspect and rehabilitate, as necessary, the LA ground water recovery wells (6.1.4)
install a new treatment system capable of handling the combined flow from the MFA,
LA, and new extraction wells (6.1.5)
Risdon RSE Report, April 11, 2003 (Revised September 1, 2004) 32
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Example Intermediate-term Goals
General time frame: to be accomplished in a timely manner but not at the expense of the short-term
goals. Appropriate completion times for some of these goals may be during 2004 and others may be as
late as 2006.
update the site conceptual model (Recommendation 6.1.6)
control migration of vapors in subsurface by enhancing SVE system (Recommendation
6.1.7)
update ground water model and use regularly to evaluate control of contaminant
migration offered by onsite wells (Recommendation 6.1.8)
delineate off site plume in both overburden and bedrock (Recommendation 6.1.9)
develop a site exit strategy that includes the set of site conditions that will allow active
remediation (i.e., the P&T and SVE systems as well as offsite remedies) to be
discontinued (Recommendation 6.4.1)
evaluate risk to additional potential offsite receptors, including the Still River, wetlands,
and other potential indoor air receptors
evaluate potential remedial strategies to control continued offsite plume migration
implement remedial strategy to control offsite migration and eliminate exposure
pathways
Example Long-term Goals
General time frame: evaluations to be accomplished in a timely manner but not at the expense of either
the short-term or intermediate-term goals. Appropriate completion times for these goals may be during
2008 and on a similar interval thereafter. Important remediation technologies or site-related
developments could accelerate the evaluation timing.
revisit operating remedies on a regular basis, perhaps every 5 years, to evaluate system
performance and identify opportunities for cost savings due to changing site conditions
consider alternative technologies to reduce contaminant concentrations and perhaps
accelerate time to closure
6.5 SUGGESTED APPROACH TO IMPLEMENTATION
The suggested approach to implementing the RSE recommendations is generally outlined in Section
6.4.1. The recommendations covered in Section 6.3 were not discussed. The RSE team assumes that the
monitoring well cap (6.3.2) will be addressed immediately and that the first quarterly report could be
submitted in June 2002.
Risdon RSE Report, April 11,2003 (Revised September 1, 2004) 3 3
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7.0 SUMMARY
The observations and recommendations contained in this report are not intended to imply a deficiency in
the work of either the system designers or operators but are offered as constructive suggestions in the
best interest of the EPA and the public. These recommendations have the obvious benefit of being
formulated based upon operational data unavailable to the original designers.
Recommendations are primarily made to improve the protectiveness of the remedy. A number of
recommendations are provided. Short-term recommendations include addressing potential ongoing
human health exposures, suggesting locations for additional extraction wells to prevent further migration
of ground water contamination from the site, and installing a suitable treatment system to address the
blended influent from all on-site extraction wells. More intermediate recommendations include updating
the site conceptual model and delineating offsite contamination. Developing a site exit strategy is also
recommended, and the RSE team provides a number of potential options for short-term, intermediate-
term, and long-term goals. The site team should develop site-specific goals as well as specific metrics
that indicate progress toward those goals.
Table 7-1 provides the net cost impacts from implementing the RSE recommendations described in
Section 6 of the report. For each recommendation, the capital and annual costs are presented as well as
the total cost, over the next 10 year period. The 10-year cost is provided both with and without
discounting, assuming all capital costs are incurred in the first year. Although a 10-year period is
assumed for this cost summary, this is not to imply that site closure will occur in 10 years. Also,
additional site activities may occur, such as active offsite remediation, that have not been quantified at
this point.
Risdon RSE Report, April 11, 2003 (Revised September 1, 2004) 34
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Table 7-1. Cost Summary Table by Recommendation
Recommendation
6. 1. 1 Perform Vapor Sampling
Within Buildings, Install Venting
Systems As Appropriate
6. 1.2 Develop and Implement
Institutional Controls
6. 1.3 Add Extraction Wells to
provide Hydraulic containment
Near the Property Boundary
6. 1.4 Inspect and Rehabilitate Wells
and Piping For The LA Extraction
System
6. 1.5 Replace Existing two
Treatment Systems With One New
System Capable of Treating A
Higher Flowrate
6.1.6 Update A Site Conceptual
Model
6.1.7 Reconfigure SVE System
(Add New SVE Wells in Selected
Areas)
6.1.8 Update/Validate Ground
Water Flow Model After New
Extraction Wells are On-Line
6. 1.9 Perform Off-Site Plume
Delineation
6.3.1 Institute Quarterly and Annual
Operations Reports
6.3.2 Repair Surface Cap For
MW-12
6.4. 1 Develop An Exit Strategy
Reason
Effectiveness
Effectiveness
Effectiveness
Effectiveness
Effectiveness
Effectiveness
Effectiveness
Effectiveness
Effectiveness
Technical
Improvement
Technical
Improvement
Site Closeout
Totals
Additional
Capital
Costs
($)
$0
$15,000
$61,000
$15,000
$453,000
$5,000
$30,000
$20,000
$56,000
$0
<$ 1,000
$20,000
$676,000
Estimated
Change in
Annual
Costs
($/yr)
$5,000
$0
$0
$0
$0
$0
$0
$0
$0
$59,500
$0
$0
$64,500
Estimated
Change
In Costs for
10 years
($)*
$50,000
$15,000
$61,000
$15,000
$453,000
$5,000
$30,000
$20,000
$56,000
$595,000
<$ 1,000
$20,000
$1,321,000
Estimated
Change
In Costs for
10 years
($)**
$40,500
$15,000
$61,000
$15,000
$453,000
$5,000
$30,000
$20,000
$56,000
$482,000
< $1,000
$20,000
$1,198,500
Costs in parentheses imply cost reductions.
* assumes a discount rate of 0% (i.e., no discounting)
** assumes a discount rate of 5% and no discounting in the first year
Risdon RSE Report, April 11, 2003 (Revised September 1, 2004)
35
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FIGURES
Risdon RSE Report, April 11, 2003 (Revised September 1, 2004)
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FIGURE 1-1. AREA SURROUNDING THE RISDON FACILITY.
OLD NEWTON ROAD
11 OLD
NEWTON
ROAD
\
CHOUSE \
OFFICE
BUILDING
>~ NORTHEASTERN
-
aj
Q_
1
>-' I LAGOON AREA (LA)
^
h-7
i
«3E
AD
:ET
! f ^
_fj
PROPERTY BOUNDARY
RISDON CORPORATION
FACILITY
^x
1 n r-rr-
FORMER SURFACE ' , ' L-1 1 U
^
1
1
^ METAL
FINISHIf
AREA
(MFA)
ASPHALT IMPOUNDMENTS
XN\
200
SCALE IN FEET
400
(Note: This figure is based on figures in site documents prepared by Woodard & Curran.)
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NORTH
A
310-1
FIGURE 1-2. GEOLOGIC CROSS-SECTION A-A' DEPICTED IN FIGURE 1-3.
SOUTH
A1
r310
MW-505
MW-506 MW-507
300-
290-
280-
270-
260-
250-
-300
VERTICAL EXAGGERATION 10X
-290
-280
-270
-260
-250
LEGEND
SCREEN INTERVAL
POTENTIOMETRIC SURFACE IN
OVERBURDEN GROUNDWATER
AUGUST 1996
0
120
SCALE IN FEET
240
600 FT
(Note: This figure is a re-creation of Figure 5-4 from the RCRA Facility Investigation Report, Woodard & Curran, January 1999.)
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FIGURE 1-3. EXTENT OF VOC CONTAMINATION BASED ON THE SEPTEMBER 2001 SAMPLING EVENT AND THE 2002 OFF-PROPERTY
SOtt, VAPOR AND GROUNDWATER SAMPLING REPORT. THE ORIENTATION OF CROSS-SECTION A-A' IN FIGURE 1-2 IS DEPICTED.
'11 / ^
^\BU'LAD"NG/
.
GW1A.B
,-
GAR-MW-1/
~1
MEDSOURCE
4 OLD NEWTON ROAD
^n
s,
/
/ s
SELF
STORAGE
MS-MW-6
O
11 OLD
MW~1.' NEWTON
-12
QMW-6
MW-8
OMW-13
ASPHALT FORMER SURFACE
::1 IMPOUNDMENTS ^N~5^, O_
N/
OLD NEWTON ROAD
^W-SCMB
MW-nr' ~ ^MW-HOA
,>
- NORTHEASTERN
_ \
| MW-113\ PROPERTY BOUNDARY'
QMW-501
- METALS /
FINISHING ,'
AREA '
(MFA) I
o
o
LEGEND
MONITORING WELLS WITH VOC CONCENTRATIONS BELOW THE
STRICTEST REMEDIATION STANDARDS
MONITORING WELLS WITH VOC CONCENTRATIONS ABOVE THE
STRICTEST REMEDIATION STANDARDS
MONITORING WELLS WITH VOC CONCENTRATIONS AT LEAST 2 ORDERS
OF MAGNITUDE ABOVE THE STRICTEST REMEDIATION STANDARDS
DIRECT-PUSH GRAB SAMPLES WITH VOC CONCENTRATIONS BELOW
THE STRICTEST REMEDIATION STANDARDS
DIRECT-PUSH GRAB SAMPLES WITH VOC CONCENTRATIONS ABOVE
THE STRICTEST REMEDIATION STANDARDS
\.
(Note: This figure is based on figures in site documents prepared by Woodard & Curran.)
0 200
SCALE IN FEET
400
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FIGURE 4-1. POTENTIOMETRIC SURFACE MAP PROVIDED IN THE JANUARY 2003 GROUNDWATER MONITORING REPORT.
/ CAR
V BUILDING /
- METALS
FINISHING;
AREA /
(MFA) i
f
MW-13
(290.48)
~~ >ORMER₯SURFACE
_IJyLPQUN_DMENTS
(290.48)
GROUNDWATER MONITORING WELL LOCATION AND IDENTIFIER
RECOVERY WELL LOCATION AND IDENTIFIER
GROUNDWATER ELEVATION ON OCTOBER 14-17, 2002
GROUNDWATER CONTOUR - SHOW INFERRED WATER TABLE
298 SURFACE. CONTOUR INTERVAL = 2 FEET. ARROWS INDICATE
DIRECTION OF GROUNDWATER FLOW
V
'\
200
SCALE IN FEET
400
(Note: This figure is a re-creation of Figure 2 from the December 2002 Quarterly Groundwater Monitoring Report submitted by Woodard & Curran to
EPA in January 2003.)
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FIGURE 6-1. RECOMMENDED LOCATIONS FOR ADDITIONAL EXTRACTION WELLS.
1
MEDSOURCE
4 OLD NEWTON ROAD
J
/ s
SELF
STORAGE
OLD NEWTON ROAD
11 OLD
NEWTON
ROAD
"\
OX
RW-3 ^
HOUSE
OFFICE
BUILDING
.
0
i
D_
<$.
^7 1 LAGOON AREA (LA)
1
J VRW-1
Co;
% r'
\GE "X 7"
AD \/
W-6 EW-5
1 P
RW-404 RW-101C
EW~4 RW-108ArpK OQ
^J RW-303
RISDON CORPORATION
FACILITY o
RW-403Q RW-302
RW-402O o
RW-401
i n , nr 1
^ NORTHEASTERN i
ROPERTY BOUNDARY'
I
1
1
1
. METALS / /
FINISHING / /
AREA ' /
(MFA) j
I
1
IMPOUNDMENTS
LEGEND
O EXISTING GROUNDWATER EXTRACTION WELLS
PROPOSED ON-SITE GROUNDWATER EXTRACTION WELLS
0 200
SCALE IN FEET
400
(Note: This figure is based on figures in site documents prepared by Woodard & Curran.)
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