United States Office of
Environmental Protection Emergency and
Agency Remedial Response
EPA/ROD/R05-93/246
September 1993
&EPA Superfund
Record of Decision:
New Brighton/Arden Hills, MN
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50272.101
REPORT DOCUMENTATION /1. REPORT NO. 2. 3. Recipient's Accession No.
PAGE EPA/ROD/ROS-93/246
4. Tille and Subtitle 5. Report Date
SUPERFUND RECORD OF DECISION 09/30/93
New Brighton/Arden Hills, MN 6.
Second Remedial Action
7. Author(s) 8. Performing Organization Rept. No.
9. Performing Organization Name and Address 10 Project TaskIWork Unit No.
11. Contract(C) or Grant(G) No.
(C)
(G)
12. Sponsoring Organization Name and Address 13. Type of Report & Period Covered
U.S. Environmental Protection Agency
401 M Street, S.W. 800/800
Washington, D.C. 20460 14.
15. Supplementary Notes
PB94-964114
16. Abstract (Limit: 200 words)
The 2S-square-mile New Brighton/Arden Hills site consists of the 4 square-mile Twin
Cities Army Ammunition Plant (TCAAP) and portions of seven nearby communities: New
Brighton, Arden Hills, St. Anthony, Shoreview, Mounds View, Columbia Heights, and
Minneapolis, located in Ramsey and Hennepin Counties, Minnesota. Land use in the area
is mixed residential, commercial, and industrial, with onsite wetlands and woodlands
surrounding the Rice Creek watershed. The site consists o£ gently rolling, postglacial
terrain with several hills and surface water bodies, including lakes and streams, but
no extreme relief. The people who reside in the vicinity of the site use the aquifers
which fall within the North Plume: the Prarie du Chien/Jordan Sandstone aquifer, the
Hillside and Arsenal Sand aquifers, and the Lacustrine Deposits, as their drinking
water supply. These aquifers supply water to TCAAP and the municipalities of New
Brighton, St. Anthony, Fridley, 'Mounds View, and Shoreview. The TCAAP facility is an
inactive small arms ammunition manufacturing plant. From 1941 to 1981, the site was
. used for the manufacture, storage, and testing of small arms ammunition and related
equipment. Waste materials such as VOCs, heavy metals, corrosive materials, and
explosives were disposed of at 14 source areas at TCAAP.. In 1981, the State began
ground water sampling and analysis which indicated that municipal and private drinking
(See Attached Page)
17. Document Analysis a. Descriptors
Record of Decision - New Brighton/Arden Hills, MN
Second Remedial Action
Contaminated Media: gw, soil, sediment, surface water
Key Contaminants: VOCs (TCE), metals
b. Identifiers/Open-Ended Terms
c. COSA TI FlelcifGroup
18. Availability Statement 19. Security Class (ThIs Report) 21. No. of Pages
None 46
20. Security Class (This Page) 22. Price
None
(See ANSI.Z39.18)
Sse Instructions on Reverse
OPTIONAL FORM 272 (4.77)
(Formerty NTIS-35)
Department of Commerce
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EPA/ROD/ROS-93/246
New Brighton/Arden Hills, MN
Second Remedial Action
Abstract (Continued)
water wells and wells at TCAAP were contaminated with VOCs. As a result, beginning in
1981, the City of New Brighton abandoned several municipal wells and either placed them on
standby or deepened several others: the Village of St. Anthony decommissioned one well
and connected a portion of the village with nearby Roseville water supplies for an
indefinite, but temporary period; a number of New Brighton/Arden Hills residents
previously drawing ground water from contaminated private wells were provided with
municipal water through the construction of a water main extension; and residents of a
nearby trailer park drawing contaminated water were provided with new wells to supply
potable water. Furthermore, additional Interim Remedial Actions were implemented as part
of the Department of Defense's Installation Restoration Program, which included the
removal of contaminated sludge and soil from Building 502 between 1984 and 1986; the
construction of in-situ soil vapor extraction (SVE) systems for remediation of
contaminated soil at Sites D and G on TCAAP in 1986; the cleaning of all sewer lines at
TCAAP in 1986; the installation of a ground water pump-and-treat system at Sites A, I, and
K in 1988; and the construction of permanent granular activated carbon treatment systen\s
for the City of New Brighton in 1990 and the Village of St. Anthony in 1991. In 1987, an
interim action ROD was written to implement a boundary ground water recovery system
consisting of 12 wells to prevent migration of contaminated ground water past the
southwest boundary of TCAAP. If 1992 ROD addressed the containment of the South plume by
extracting ground water from its leading edge, as OU3. The thermal treatment of
approximately 1,400 yd3 of PCB-contaminated soil at Site D in 1989. This ROD addresses
the North Plume of offsite contaminated ground water. Future RODs will address onsite
soil, ground water, sediment, and surface water, as OU2. The primary contaminants of
concern affecting the ground water are VOCs, including TCE; and metals.
The selected remedial action for this site includes providing an alternative water supply
to residents with private wells under State drinking water advisories within the impacted
zone; implementing a ground water extraction scheme for plume containment; treating the
extracted ground water onsite by oxidation and filtration to remove iron and mangan~se,
followed by pumping the treated water to a permanent onsite GAC system; discharging all
treated water offsite to the New Brighton municipal distribution system; monitoring ground
water; and implementing institutional controls, including ground water use restrictions.
.The estimated present worth cost for this remedial action is $10,310,000, which includes
an estimated annual O&M cost of $704,700 for 30 years.
PERFORMANCE STANDARDS OR GOALS:
Chemical-specific ground water cleanup goals are based on SDWA MCLs or health-based State
levels, and include 1,1-DCA 70 ug/l; 1,1-DCE 6 ug/l; cis-1,2-DCE 70 ug/l; 1, 1, 1-TCA 200
ug/l; 1,1,2-TCA 3 ug/l; and TCE 5 ug/l.
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RECORD OF DECISION
GROUNDW A TER REMEDIATION
OPERABLE UNIT 1
AT NEW BRIGHTON/ARDEN lllLLS
SUPERFUND SITE
. SEPTEMBER 1993
In accordance with Anny Regulation 200-2, this document is intended to
comply with the National Environmental Policy Act (NEP A) of 1969.
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I.
DECLARATION FOR THE RECORD OF DECISION
A.
Site Name and Location
New Brightonl Arden Hills (NBI AH) Superfund Site, also known as Twin Cities Army
Ammunition Plant (TCAAP), Ramsey County, Minnesota.
B.
Statement of Basis and Purpose
This decision document presents the selected remedial action for addressing groundwater
contamination at operable unit 1 (QU-I) of the New Brightonl Arden Hills Superfund Site in
Ramsey County, Minnesota, which was chosen in accordance with the requirements of the
Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA),
as amended by the Superfund Amendments and Reauthorization Act of 1986 (SARA), the
Minnesota Environmental Response and Liability Act (MERLA), and, to the extent practicable,
the National Oil and Hazardous Substances Pollution Contingency Plan (NCP). The remedial
action was selected by the United States Environmental Protection Agency (EPA) and the
Minnesota Pollution Control Agency (MPCA), together with the United States Army (Army)
pursuant to the Federal Facilities Agreement (FF A) among the three parties.
This decision document explains the factual and legal basis for selecting the remedy for this site.
The information supporting this remedial action decision is contained in the Administrative
Record for this site.
c.
Assessment of the Site
Actual or threatened releases of hazardous substances from this site, if not addressed by
implementing this Record of Decision (ROD), may present an imminent and substantial
. endangerment to public health, welfare, or the environment.
D.
Description of the Selected Remedy
The NBI AH site has been divided into three operable units. The first operable unit, aU-I,
addressed by the remedy selected in this ROD, consists of the North Plume of off- TCAAP
contaminated groundwater. The second operable unit, OU-2, consists of the on-TCAAP soils,
groundwater, sediments, and surface waters. A remedy for OU-2 is expected to be proposed
in mid-1994. The third operable unit, QU-3, consists of the South Plume of off-TCAAP
contaminated groundwater. A ROD has already been issued for OU-3, for which the selected
remedy is to contain the South Plume by extracting groundwater from its leading edge, thus
preventing further contaminant migration into areas that have not been impacted.
For OU-l, the major components of the selected remedy include the following:
1
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E.
.
Providing an alternative water supply to residents with private wells within the
North Plume
.
Implementing drilling advisories that would regulate the installation of new
private wells within ~e North Plume as a Special Well Construction Area
Extracting groundwater at the containment boundary in the North Plume near
County Road E
.
.
Pumping the extracted groundwater to the Permanent Granular Activated Carbon
Water Treatment Facility (pGAC) in New Brighton for removal of volatile
organic compounds (VOCs) by a pressurized GAC system
.
Discharging all of the treated water to the New Brighton municipal distribution
system
.
Monitoring the groundwater to verify the effectiveness of the remedy
Statutory Determinations
The selected remedy is protective of human health and the environment, complies with Federal
and State requirements that are legally applicable or relevant and appropriate to the remedial
action, and is cost-effective. This remedy utilizes permanent solutions to the maximum extent
practicable, and satisfies the statutory preference for remedies that employ treatment that reduces
toxicity, mobility, or volume as a principal element. Because this remedy will result in
hazardous substances remaining on-site above health-based levels, a review will be conducted
within five years after commencement of the remedial action to ensure that the remedy continues
to provide adequate protection of human health and the environment.
it
If ~, If93,
Da
Date
Charles W. Williams
Commissioner .
Minnesota Pollution Control Agency
Date
Lewis D. Walker
. Deputy Assistant Secretary of Army for
Environment, Safety, and Occupational Health
2
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Providing an altemaUve water supply to x=dentS with privaa=. wells within the
Nonb Plume
Implementing drilling advisories that would regulate the insII11ation of DeW
privata wells within the North Plwne u a Special wen ~ Area
.
.
Emactmg If'OW1Ciwater at the containment boundary in the NOrth Plume near
Cowuy RoId E
~ the extracted I1'OUDdwater to the Perml.DeDt GI2m118r Activated Carbon
Wara TreatmeI1t Facility (PGAC) in New Brighton for removal of volatile
orpnic: compounds (V0Cs) by a pressurized GAC syStem
.
.
Discharging aJ1 of the tr=ed watI!:r to the New Brighton municipal distribution
system
Moaitoring the groundwater to verify the effectiveness of the remedy
.
Staftltory Determloadoas
The selected remedy is pror=1ve of human health and the environment, complies with Pederal
IDd State requiremeDts th2t are lep1ly applicable or re1tMU1t and A{llI~v9ciatc to ttn: mnedia1
&tion, and is cost-eff'ecti~ 'Ibis remedy utilizes pennaDeDt solutions to the maximum extent
pncticab1e, and satisfies the SWUtOry 9itferedce for remedies that emp!oy treatment that reduces
~, mobility, or volume CD a pdndpa1 element. Because this remedy wi1l result in
hazardous substances remaminc on-e above hea1th..oased levels, a review will be conduCted
within five yeas after commencem=t of the remedial action to ensure thatd1e {em~y GOftQnUC3
to provide adequate PI~~ of human bealth and the environment.
VaJda v. .A.~"
ReaianaI AdmiDi.sttatcr
V.S. EIIviroameata1 p!\)Cection Apnr;y
IIpm V
Date
Oada .W. WtmaftH
Commiaioner
!tfI,,~ PoUution Control Aptrr:y
~'t:J,~
. D. Wa1kl:t
Deputy "uiant Secretazy of Army for
Em~04dIIDc. Safety, and Occupatioaal Health
Date
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Date
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.Providing an alternative water supply to residents with private wells within the]
North Plume
Implementing drilling advisories that would regulate the installation of new]
private wells within the North Plume as a Special Well Construction Area
Extracting groundwater at the containment boundary in the North Plume near
County Road E
Pumping the extracted groundwater to the Permanent Granular Activated Carbon
Water Treatment Facility (PGAC) in New Brighton for removal of volatile
organic compounds (VOCs) by a pressurized GAC system
Discharging all of the treated water to the New Brighton municipal distribution
system
Monitoring the groundwater to verify the effectiveness of the remedy
£. Statutory Determinations
The selected remedy is protective of human health and the environment, complies with Federal
and State requirements that are legally applicable or relevant and appropriate to the remedial
action, and is cost-effective. This remedy utilizes permanent solutions to the maximum extent
practicable, and satisfies the statutory preference for remedies that employ treatment that reduces
toxicity, mobility, or volume as a principal dement. Because this remedy will result in
hazardous substances remaining on-site above health-based levels, a review will be conducted
within five years after commencement of the remedial action to ensure that the remedy continues
to provide adequate protection of human health and the environment.
Valdas V. Adamkus
Regional Administrator
U.S. Environmental Protection Agency
Radon V
Date
W. Williams
Commissioner
Minnesota Pollution Control Agency
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ll.
DECISION SUMMARY
A.
Site Name, Location, and Description
The NBI AH site consists of a 25-square-mile area located in Ramsey County and Hennepin
County, Minnesota just north of the Minneapolis-St. Paul metropolitan area. This includes the
4-square-mile TCAAP facility and portions of seven nearby communities: New Brighton, Arden
Hills, St. Anthony, Shoreview, Mounds View, Columbia Heights, and Minneapolis (Figure 1).
Land use in this generally suburban area is mixed residential, commercial, and industrial. As
presently defined, the site covers much of the U.S. Geological Survey's New Brighton,
Minnesota 7.5-minute quadrangle.
The site consists of gently rolling, postglacial terrain with several hills and surface water bodies,
including lakes and streams, but no extreme relief. The site is located within the Rice Creek
watershed. Rice Creek and its surrounding marshes and woodlands provide cover for a variety
of vegetation and wildlife. Much of the lowland area adjacent to Rice Creek has lush and
vigorous vegetation creating a wildlife habitat well suited to small animals.
The TCAAP facility is an inactive small arms ammunition manufacturing plant. It is currently
operated by Federal Cartridge Company (FCC) and used by two manufacturing lessees, Alliant
Techsystems (previously a branch of Honeywell, Inc.) and 3M Corporation. Approximately
1,000 people are currently employed at TCAAP.
B.
Site History and Enforcement Activities
TCAAP has been used to manufacture, store, and test small arms ammunition and related
materials since 1941. Information from past studies indicates that between 1941 and 1981, waste
materials such as VOCs, heavy metals, corrosive materials, and explosives were disposed of at
14 source areas within TCAAP. In 1981, the MPCA and the Minnesota Department of Health
(MDH) began groundwater sampling and analysis. Samples were collected from wells in the
TCAAP area. The analytical results from these samples indicated that municipal and private
. drinking water wells and wells at TCAAP were contaminated by VQCs. As a result, the
following actions were taken:
.
The City of New Brighton abandoned several municipal wells and either placed
on standby or deepened several others.
.
The Village of St. Anthony decommissioned one well and connected a portion of
the village with Roseville water supplies for an indefinite but temporary period.
.
A. number of New Brightonl Arden Hills residents drawing contaminated
groundwater from private wells were provided with municipal water through the
construction of a water main extension.
.
Residents of the Arden Manor Trailer Park drawing contaminated groundwater
from private wells were provided with new wells to supply potable water. The
wells were provided by Arden Manor Trailer Park, which was later reimbursed
by the Army.
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The NBI AH site was proposed for inclusion on the National Priorities List (NPL) in July 1982
and finalized in September 1983, with a Hazard Ranking System (HRS) score of 59 and a
ranking of 43 on the NPL. In 1981, the Army began a Phase I investigation at TCAAP which
involved a significant quantity of monitoring wells and sampling efforts designed to identify the
overall contribution of TCAAP to the groundwater contamination. In 1983, EPA's Field
Investigation Team completed a documentation record and site assessment for the site. The
assessment documented high conce~trations of VOCs in groundwater at the site. Releases of
these compounds from the site to surface water and direct human contact with the compounds
were also documented. The elevated HRS score and correspondingly high NFL ranking reflect
the following site conditions: 1) the relatively large number of individuals exposed to
contaminated groundwater through their potable water supplies, and 2) the potentially
carcinogenic nature of the compounds.
The NBI AH site, as currently defined, consists primarily of portions of several regional aquifers
that are contaminated to differing degrees with VOCs. Concentrations for several of these
compounds exceed current health-based criteria. The affected aquifers supply water to TCAAP
and the municipalities of New Brighton, St. Anthony, Fridley, Mounds View, and Shoreview.
On TCAAP itself, contamination of soils, sediments, and surface waters is also of concern.
PROBLEM DEFINITION
Groundwater contamination emanating from TCAAP, identified as the primary source of
groundwater contamination within the area of the NBI AH site, has posed a potential health
hazard. This hazard potentially results from direct human contact (dermal contact, inhalation,
or ingestion) of groundwater contaminated with industrial solvents including trichloroethene
(TCE) , dichloroethene (DCE), trichloroethane (TCA), and dichloroethane (DCA). Studies
concerning VOCs in groundwater within the study area have been undertaken prim~y by the
Army, Alliant Techsystems, MPCA, EP A, and private entities. These studies have largely
involved the installation and sampling of monitoring wells and water quality surveys of
production, municipal, and residential wells. The objectives and results of the studies are
summarized as follows.
. PREVIOUS STUDIES
Army reports of investigations and studies at TCAAP in 1983 and 1984 identified major and
minor disposal areas on the facility that were sources of release or threatened release of
hazardous substances (mainly VOCs). In their review of these reports, EPA and MPCA noted
that additional information was needed to address the extent and magnitude of contaminated
groundwater, to fill data gaps relative to off-site contamination, and to complete an assessment
of the disposal areas identified on TCAAP.
In 1984 and 1985, the Army submitted investigative reports addressing VOC contamination at
Alliant-TCAAP buildings 103 and 502 (Sites I and K). The reports indicated that the buildings'
operations were a source of VOC-contarninated groundwater migrating towards Rice Creek from
Building 103, and also to the west or southwest from the Building 502 area. As a result of these
findings, Alliant announced a three-phase off-TCAAP investigation on July 28, 1984, to
supplement work being conducted by MPCA to identify off- TCAAP sources of release.
4
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In the spring of 1985, EPA initiated an investigation of the force mains outside TCAAP because
a number of docu-mented breaks had occurred in the line in the st1.Jdy area and because VOCs
and other hazardous wastes and metals had been detected in the sewer sediments on TCAAP.
Also in 1985, MPCA released the Phase I Final Report. New Brightonl Arden Hills. Minnesota
Multi-Point Source Remedial Investigation. The report identified four potential source areas of
VOC release in the study area that had possibly contaminated the groundwater. The source
areas included two areas at TCAAP and two areas adjacent to TCAAP. A second phase of the
off-TCAAP RI, Phase lA, was initiated in July 1986 and completed in February, 1991. The
purpose of the Phase IA RI was to further define the nature and extent of groundwater
contamination in off- TCAAP areas.
In 1988, the Army initiated an on-TCAAP RI designed to characterize the nature and extent of
contamination within the facility boundary, addressing soils, sediments, surface waters, and
groundwater. The on-TCAAP RI was completed in April, 1991.
Additionally, in 1991, EPA completed the Human Health Risk Assessment and the Army
completed the Environmental Risk Assessment. The completion of these four documents led to
the development of feasibility studies for final remedial actions at the NBI AH site;
INTERIM REMEDIAL ACTIONS
Most of the interim remedial actions (!RAs) taken at TCAAP have been implemented under the
Army Installation Restoration Program (IRP). These actions have been coordinated with federal
and state regulatory agencies prior to implementation. Alliant Techsystems entered into an
agreement with the Army in 1985 to investigate and pursue the cleanup of sites at TCAAP
associated with Alliant operations. Industrial operations at TCAAP have generated ~ost of the
contamination currently migrating from the site. The!RAs being conducted by the Army and
Alliant have concentrated on contaminant source control, with a focus on individual site cleanups
and groundwater (aquifer) remediation. Actions that have already been taken can be divided into
the categories of : a) alternative water supplies, b) unilateral actions by the Army, c) actions
with EPA and state concurrence, and d) other actions initiated by EPA, MPCA, and/or Army.
a)
Alternative Water Supplies
In addition to the previously mentioned alternative water supplies that were provided shortly
after the discovery of contamination at the site, the following systems have been completed:
.
A temporary, followed by a permanent, granular activated carbon (GAC)
treatment system constructed for the City of New Brighton by the Army as part
of a litigation settlement agreement. The permanent system, completed in June
1990, presently treats water from New Brighton Wells 3, 4, 5, and 6 and has a
capacity of 3800 gallons per minute (gpm).
.
A temporary, followed by a permanent, GAC treatment system constructed for
the Village of St. Anthony by EP A and MPCA. The permanent system is a
remedial action pursuant to a ROD signed in September 1986. The system,
completed in April 1991, treats water from St. Anthony Wells 3, 4, and 5 and
has a capacity of 2400 gpm.
5
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b)
Unilateral Actions by the Army
Unilateral removal actions have been taken by the U.S. Army using its own delegated removal
authorities under CERCLA section 104. These actions have included:
c)
.
In-situ soil vapor extraction (ISV) systems for the remediation of contaminated
soils at Sites D and G on TCAAP. The ISV systems were implemented in 1986
and, since then, have removed over 115 tons of VOCs from site soils.
.
A groundwater pump-and-treat system at Site A, where the surficial aquifer is
contaminated with VQCs. The system, installed by the Army in 1988, utilizes
liquid-phase GAC to treat extracted groundwater, which is then
surface-discharged.
.
Groundwater pump-and-treat systems installed in 1988 at Sites I and K, Alliant
operations buildings. Groundwater underneath the buildings is contaminated with
VOCs with the likely source identified as leaks from floor drains and sewer lines.
The extracted groundwater is treated by air stripping. The treated groundwater
from Site K is discharged to a sewer under a National Pollutant Discharge
Elimination System (NPDES) permit issued by the state. The treated
groundwater from Site I is discharged to the TCAAP Groundwater Recovery
System (TGRS). The TGRS is more fully described in the next section.
Actions with EP A and State Concurrence
.
In 1987, the Army implemented the Boundary Groundwater Recovery System
(BGRS), for which the EPA signed a ROD in September 1987. 1Jris system
initially consisted of a series of six groundwater extraction wells located along the
southwest boundary of TCAAP and designed to prevent any further migration of
contaminated groundwater off of TCAAP. After a period of performance
monitoring, the system was expanded in 1989 to twelve wells. Eight of the
BGRS wells draw water from the Hillside Sand aquifer with the other four
drawing from the Prairie du Chien aquifer.
.
The BGRS operates at an extraction rate of approximately 2100 gpm. Extracted
water is pumped to an air stripping facility for the removal of VOCs. From there
the treated water is pumped to the Arsenal. Sand and Gravel Pit in the
north-central portion of TCAAP, where it is discharged and allowed to infiltrate
back into the ground. Over five billion gallons of water have been treated and
45 tons of VOCs have been removed by this system.
.
In addition to the implementation of the BGRS, the Army subsequently installed
five source control (SC) wells downgradient of Sites D, G, and 1. The BGRS and
SC wells together comprise the TCAAP Groundwater Recovery System (TGRS).
The TGRS is designed to provide regional groundwater remediation at TCAAP
and prevent additional contamination from migrating beyond the facility
boundaries.
6
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d)
Other Actions Initiated by EPA, MPCA and/or Army
.
Site J, the sanitary sewer system at TCAAP, has been investigated in several
studies. In 1983, integrity testing was conducted on part of the upper plant sewer
and on the 18-inch and 24-inch force mains. During 1984, approximately 50
percent of the sanitary sewer system (over 42,000 linear feet) was inspected,
cleaned, and tested. By July 1986, cleaning of all sewer lines was completed.
.
Between 1984 and 1986, Alliant Techsystems removed contaminated sludge from
the sewers leading away from Building 502, containerized the sludge in drums.
and stored it in a building called the Retrievable Monitored Containment Structure
(RMCS). In addition, in 1985, Alliant excavated PCB-contaminated soils around
Building 502 and placed them in the RMCS.
.
About 1400 cubic yards of PCB-contaminated soil at Site D were thermally
treated in 1989. EPA prepared the ROD and the risk assessment report for this
action.
.
The Army completed a two-phase water management study to evaluate feasible
alternatives for the disposal of treated groundwater anticipated from future
remedial measures.
CERCLA ENFORCEMENT ACTIVITIES
Pursuant to Section 120 of the Superfund Amendments and Reauthorization Act of 1986
(SARA), the Army entered into a Federal Facilities Agreement (FFA) with EPA and the State
of Minnesota. The TCAAP FFA, which became effective on December 31, 1987, ~as the first
to be negotiated between EP A and any federal agency since the enactment of SARA. The
general purposes of the FF A are to:
1)
Ensure that the environmental impacts associated with past and present activities
at TCAAP are thoroughly investigated and that appropriate remedial actions are
taken to protect the public health, welfare, and the environment.
2)
Establish a procedural framework and schedule for developing, implementing, and
monitoring appropriate response actions in accordance with CERCLAISARA, the
National Oil and Hazardous Substances Pollution Contingency Plan (NCP) ,
Superfund guidance and policy, the Resource Conservation and Recovery Act
(RCRA), and RCRA guidance and policy.
3)
Ensure cooperation, information exchange, and participation of the parties in such
actions.
The specific purposes of the agreement are to:
" . --....-..... .-'"
1)
Identify interim remedial action alternatives appropriate for preventing further
migration of contaminated groundwater prior to the implementation of final
remedial actions for the site.
7
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C.
2)
Establish requirements for conducting the on- TCAAP RI to determine fully the
nature and extent of the threat to the public health, welfare, or the environment
caused by the release and threatened release of hazardous substances, pollutants,
or contaminants at TCAAP.
3)
Establish requirements for conducting an FS for the site to identify, evaluate, and
select alternatives fo~. the appropriate remedial action(s) to prevent, mitigate, or
abate the release or threatened release of hazardous substances, pollutants, or
contaminants at the site in accordance with CERCLA and SARA.
4)
Identify the nature, objective, and schedule of response actions to be taken at the
site. Response actions at the site shall attain a degree of cleanup of hazardous
substances, pollutants, or contaminants mandated by CERCLA and SARA.
5)
6)
Implement the selected interim and final remedial action(s).
Assure compliance with federal and state hazardous waste laws and regulations
for matters covered by the agreement.
Highlights of Community Participation
The community near TCAAP has been involved in site activities since the environmental
problems related to the TCAAP facility were identified. Numerous fact sheets have been sent
and public meetings have been held to keep the community apprised of the various remedial
activities at the site.
.
For the remedy selection for OU-l, the public participation requirements of CERCLA Sections
113 (k) (a) (B) (i-v) and 117 were met through the issuance of a fact sheet and Proposed Plan,
notification of the availability of the Proposed Plan by newspaper, and the holding of a Public
meeting on August 19, 1993. The public comment period for the Proposed Plan began on
August 6, 1993, and ended on September 7, 1993.
D.
Scope and Role of Operable Units Within the Overall Cleanup Strategy
The NB/AH site has been divided into three operable units. The fIrst operable unit, OU-I,
addressed by the remedy selected in this ROD, consists of the North Plume of off-TCAAP
contaminated groundwater. The second operable unit, OU-2, consists of the on-TCAAP soils,
groundwater, sediments, and surface waters. The third operable unit, OU-3, consists of the
South Plume of off- TCAAP contaminated groundwater. A conceptual illustration of the three
operable units is presented in Figure 2.
The main role of OU-l is the containment of the North Plume of off- TCAAP contaminated
groundwater, while the role of OU-3 is the containment of the South Plume. Implementation
of the remedies for OU-l and OU-3 will provide overall protection of human health and the
environment. By extracting contaminated groundwater to hydraulically contain the most
contaminated portions of the North Plume and fully contain the South Plume, remedial actions
at OU-l and OU-3 will also provide removal of contaminant mass from the system. However,
8
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hazardous substances will remain in the groundwater above health-based levels for a long period
of time. To mitigate this situation, a more aggressive strategy for removing contaminant mass
will be integrated into the objectives of OU-2. Mass removal will be more effective in OU-2
because the source areas of contamination are located within this operable unit.
E.
Summary of Site Characteristics
Within the NB/ AH study area, groundwater is found in both bedrock and glacial deposit
aquifers. On top of the irregular bedrock surface, a series of unconsolidated glacial sediments
has been deposited. Several of these units are water-bearing and have been affected by the
spread of contaminants from TCAAP.
The Prairie du Chien/Jordan Sandstone aquifer is the principal aquifer in the Twin Cities Basin.
This aquifer is referred to as Unit 4. Permeability in the Prairie du Chien/Jordan Sandstone
aquifer is controlled by the extent of fractures and joints in the Prairie du Chien unit and the
porosity of the Jordan Sandstone unit. Groundwater flow through this aquifer is generally in a
west-southwest to south-southwest direction off- TCAAP toward the Mississippi River. Recharge
to the Prairie du Chien/Jordan Sandstone aquifer occurs by infiltration through the overlying
glacial units.
The Hillside Sand and the Arsenal Sand are referred to as Unit 3. Within the New Brighton
quadrang~e, the Hillside/ Arsenal Sand outcrops in four areas: the Arsenal Kame within TCAAP;
the southwestern comer of the quadrangle within Minneapolis; two small areas in Columbia
Heights in the vicinity of Silver Lake; and along the southern edge of Snail Lake. Except for
the exposure in Minneapolis, the Hillside! Arsenal Sand directly overlies the Prairie du
Chien/Jordan Sandstone aquifer; the other three surface exposures provide direct ~echarge to
both units. The groundwater in Unit 3 flows predominantly southwest.
The Twin Cities Till overlies the Hillside Sand in much of the area and is referred to as
Unit 2. The Twin Cities Till acts as an aquitard, Le., a confining layer that prevents direct
hydraulic communication between the overlying Lacustrine Deposits and the Hillside Sand
below.
The Lacustrine Deposits, referred to as Unit 1, are predominantly fine to medium sands with
interbedded silt layers and occasional minor peat and clay layers. These units form the shallow
surface aquifer between and to the north of the Hilltop and Arden Hills moraines. Private wells
installed in Unit 1 exist to the north of TCAAP. Groundwater in this unit is perched and
discontinuous. Any groundwater flow is localized and toward the closest small lake.
Groundwater in aquifer Units 1, 3, and 4 has been contaminated by chemicals coming from one
or more of the, 14 source areas identified on the TCAAP facility. Outside TCAAP, VOCs
within the North Plume migrate horizontally and downward vertically in response to
corresponding hydraulic gradients. The North Plume migrates in a southwesterly direction in
both the Hillside Sand and Prairie du Chien aquifers. The North and South Plumes diverge
immediately off TCAAP with the South Plume moving in a more southerly direction.
9
'~-"- . ".' "", -------.... . ...
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F.
Summary of Site Risks
A human health risk assessment for TCAAP was performed by EPA in 1991. The risk
assessment evaluated the potential risks associated with the source areas at the site as well as the
contaminated groundwater both on-TCAAP and off-TCAAP. It also evaluated the ways by
which people could be exposed to contaminants. These potential exposure pathways are
ingestion, inhalation during showeIjng, an~ absorption through the skin (dermal contact) during
showering or bathing with contaminated groundwater.
The public water supplies in New Brighton, St. Anthony, and the TCAAP area treat their
potable water using granular activated carbon to remove organic contaminants. However, a
small number of residents may rely on private drinking wells located within the North Plume.
These residents are the potential receptors at risk from the contaminated groundwater.
The following compounds have been identified as the most prevalent chemicals of concern in
the groundwater: chloroform; 1, 1-dichloroethane; 1, I-dichloroethene; 1,2-dichloroethene;
1,1, I-trichloroethane; trichloroethene; and bis(2-ethylhexyl)phthalate. These contaminants could
pose an increased carcinogenic risk to those exposed to the contamination. This risk is over and
above the average or "background" level of cancer occurrence in the general population, which
is about one in three or 33 percent.
Based on the EP A risk assessment, it was estimated that maximum exposure to the chemicals
at the site could result in an increased cancer risk of one in one hundred (10-2) or one percent.
This projected increase was based on the assumption that those exposed would use untreated
ground-water from private wells installed in the most contaminated part of the North Plume and
that this exposure would last for an average lifetime. The projected one percent increase in the
risk of cancer is well over the amount EP A and MPCA consider acceptable. Indeed, Federal
and State regulations often require action when the increased cancer risk reaches the range of
one in ten thousand (IQ4) to one in one million (l~). In addition, the Hazard Index for
Carcinogenic Mixtures, as calculated from MiM. Proposed Rule 4717.7700 (see Table 7)
exceeds the acceptable value of 1.0, which represents a lifetime risk level of one in one hundred
thousand (10-').
Noncarcinogenic risk, such as the risk of liver damage or reproductive abnormalities, is
evaluated through the calculation of a hazard index for each chemical of concern. The hazard
index accounts for either the short-term (acute) or long-term (chronic) exposure via ingestion,
inhalation, and dermal contact. Noncarcinogenic risk for a given contaminant exists when the
hazard index is greater than one (1.0). The hazard index for one of the contaminants of concern .
(I, I, I-trichloroethane) in the North Plume exceeds 1.0 in two exposure areas. In addition, the
Hazard Index for Noncarcinogenic Mixtures, as calculated from Minn. Proposed Rule 4717.7700
(see Table 7), exceeds the acceptable value of 1.0, which represents the health risk limit for
noncarcinogenic mixtures.
The exposure areas associated with off-post Units 3 and 4 groundwater contamination are shown
in Figures 3 and 4, respectively. The excess lifetime cancer risks and the hazard indices for
exposure to off- TCAAP groundwater are summarized in Table 1.
In addition to the EP A-conducted human health risk assessment, the Army conducted an
ecological risk assessment at TCAAP. For the most part, the ecological risk assessment
10
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addressed on- TCAAP risks to plants and animals, and concluded that no significant risks exist.
For off- TCAAP groundwater contamination, it was inferred that the contaminated groundwater
in the deep aquifers does not pose any risks to plants and animals.
In summary, actual or threatened releases of hazardous substances from this site, if not
addressed by implementing the remedial action selected in this ROD, may present an imminent
and substantial endangerment to public health, welfare, or the environment.
G.
Description of Alternatives
The Feasibility Study for aU-l was performed in accordance with EPA guidance for Superfund
Remedial Investigations and Feasibility Studies. Table 2 presents a tabular summary of the
technology screening for aU-I. The potentially feasible remedial technologies retained from
the screening are listed in Table 3. These technologies were combined into various remedial
alternatives, which were then developed and screened. Three remedial alternatives were retained
for detailed analysis:
Alternative 1: No Action
The no-action alternative is a baseline against which other alternatives are compared, as required
by the NCP for Superfund sites. Under this alternative, no additional remedial action would be
undertaken for the North Plume. Groundwater monitoring would continue under the existing
FF A. The PGAC would continue to operate as it is currently operating and the PGRS would
operate at a nominal capacity of 1,000 gpm. The no-action alternative provides no additional
protection of human health or the environment.
The estimated 30-year present worth cost for continued semiannual groundwater monitoring is
approximately $726,000 (Table 4).
Alternative 2: Mass Removal Alternative
. This alternative includes providing an alternative water supply to residents with private wells
with MDH drinking water advisories within the impacted zone, implementing drilling advisories
that would regulate the installation of new private wells within the zone impacted by the
contamination as a Special Well Construction Area, installing three new wells in the area of
highest concentrations of contamination, pumping the extracted water to the PGAC, installing
and operating an iron and manganese removal system upstream of the PGAC carbon units, and
discharging a portion of the treated water to the New Brighton municipal distribution system
interconnect.
The extraction well placement for this alternative is illustrated in Figure 5. The three new
extraction wells (MR-l, MR-2, MR-3) would be screened in the Unit 3 and Unit 4 aquifers and
would extract groundwater at a total flowrate of 2,250 gpm. Four existing PGAC wells (NB3,
NB4, NB5, and NB6) would continue pumping at a rate of approximately 1,350 gpm, while the
PGRS would be operated at 1,000 gpm. The extracted water from the new extraction wells
would be pumped to the PGAC, which would bring its total operating flowrate to approximately
3,600 gpm. This is below the plant's maximum operating capacity of 3,800 gpm.
11
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Pumping untreated water to the PGAC would require easements for the pipeline that would run
from the new extraction wells to the PGAC. A 24-inch sanitary forcemain runs from TCAAP
along 5th Ave., northwest from the TCAAP boundary to Interstate 694. This forcemain is
within 0.5 miles of the proposed extraction wells. South of Interstate 694, the forcemain takes
ajog and runs east along 7th Street, south along 23rd Avenue, and then south along Silver Lake
Road. At this point, the forcemain is within 1,500 feet of the PGAC. A 16-inch pipe would
be required to convey 2,250 gpm of untreated water at a flow velocity of about 5 feet per
second. The 24-inch sanitary foreemain could serve as a secondary containment, although
Minnesota does not require secondary containment at this time. About 3 miles of pipe would
be required.
Alternative 2 includes the construction and operation of an oxidation/fIltration system to remove
the iron and manganese from the groundwater before it is pumped through the carbon adsorption
units. A building area of approximately 50 feet by 100 feet is needed for this pretreatment
system. Because space within the PGAC building is not available, an additional building for the
inorganics treatment system is included in this alternative.
A major issue associated with Alternative 2 is that of managing excess treated water from the
PGAC. The New Brighton municipal distribution system can accept a maximum of 2,500 gpm,
which is far below the expected total flowrate of 3,600 gpm for this alternative.
Based on the groundwater modeling efforts, Alternative 2 is expected to remove an estimated
83% of the mass of contaminants after 30 years of operation, and an estimated 86% after 100
years. The North Plume will not be fully contained; contaminated groundwater is expected to
continue migrating southward.
The estimated 3O-year present worth cost for Alternative 2 is $14.2 Million. Tabl~ 5 presents
a more detailed cost breakdown of this alternative.
Alternative 3: Containment Alternative
This alternative includes providing an alternative water supply to residents with private wells
. with MDH drinking water advisories within the impacted zone, implementing drilling advisories
that would regulate the installation of new private wells within the zone impacted by the
contamination as a Special Well Construction Area, implementing a groundwater extraction
scheme for plume containment, pumping the extracted water to the PGAC, installing and
operating an iron and manganese removal system upstream of the PGAC carbon units, and
discharging all of the treated water to the New Brighton municipal distribution system.
The extraction well placement for this alternative is illustrated in Figure 6. The two new
extraction wells (NB14 and NB15) would be screened in the Unit 4 aquifer, one near the comer
of 7th Street NW and 13th Avenue, and the other in the vicinity of NB5 and NB6. The water
from the new wells would be conveyed to the PGAC using the 24-inch sanitary forcemain that
runs along 7th Street. Two existing PGAC wells (NB3 and NB4) would continue pumping,
while the PGRS would be operated at 1,000 gpm. The extracted water from the new wells
would be pumped to the PGAC, which would bring its total operating flowrate to approximately
2,200 gpm.
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The construction and operation of the inorganics treatment facility is the same as described for
Alternative 2. "
Based on the ground-water modeling efforts, Alternative 3 is expected to remove an estimated
68% of the mass of contaminants after 30 years of operation, and an estimated 77% after 100
years. This alternative will contain the North Plume in the vicinity of County Road E and
provide for the water to be treated to a TCE concentration of 5 p.gJL.
."
The estimated 30-year present worth cost for Alternative 3 is $10.3 Million. Table 6 presents
a more detailed cost breakdown of this alternative.
H.
Summary of the Comparative Analysis of Alternatives
This section discusses how the alternatives retained for detailed analysis compare to one another
when measured against the EPA's nine evaluation criteria for addressing Superfund sites. Each
of the nine criteria are briefly described before the alternatives are evaluated against them.
1)
Overall Protection of Human Health and the Environment
The analysis with respect to overall protection of human health and the environment provides
a summary evaluation of how the alternative reduces the risk from potential exposure pathways
through treatment, engineering, and/or institutional controls. An examination of whether
alternatives pose any unacceptable shon-term or cross-media impacts is also included in this
analysis.
Alternative 1: The no-action alternative is not effective in preventing human exposure to
contaminated water that could result in unacceptable risks to human health. Private wells may
currently be located within the current or potential future plume boundaries. In some areas,
there are no regulations that would prevent private citizens from locating wells within the plume
boundaries. The greatest excess lifetime cancer risk estimated for exposure by an off- TCAAP
resident to the contaminated groundwater is 1 x 10-2. This value is above both the EP A range
for acceptable risk (Le., lQ-4 to 1~ and the MPCA acceptable risk value of 1O's. The EPA
. acceptable benchmark for noncarcinogenic risk was also exceeded in two of the exposure areas
~al~ted. "
Alternative 2: This alternative protects human health by removing VOCs from the groundwater
and by implementing institutional controls that prevent exposure to contaminated groundwater.
Residents with private wells with MDH drinking water advisories located within the impacted
zone will be provided with an alternative water supply. In addition, a Special Well Construction
Zone will be designated that would regulate installation of wells in the impacted zone. This
alternative also, includes new facilities to remove iron and manganese thereby meeting all the
water quality objectives for potable supply. However, it can be seen in Figure 5 that the plume
breaks through between the PGAC and the PGRS; thus, the contaminants will continue to
migrate towards the Mississippi River. Therefore, this alternative does not prevent the further
spread of contaminated groundwater into portions of the aquifer that are significantly less
contaminated and provides less protection of human health for potential well users within and
beyond the current plume boundary.
13
.' , . '."'. ."'~. . ".'." .' .
.. ... -.. . 4-
. ....... ,-"-- .
.....~--
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Alternative 3: This alternative protects human health and the environment by containing the
plume in the vicinity of County Road E, by removing vacs from the groundwater and by
implementing institutional controls that prevent exposure to contaminated groundwater.
Residents with private wells with MDH drinking water advisories located within the impacted
zone will be provided with an alternative water supply. In addition, drilling advisories would
be implemented in the impacted zone. This alternative also includes new facilities to remove
iron and manganese thereby meeting all the water quality objectives for potable supply. Figure
6 shows that this alternative provides a more effective capture zone than Alternative 2.
Although the alternative does not contain the plume beyond the vicinity of County Road E, it
does contain the most contaminated portions of the North Plume and prevents it from spreading
further. For this reason, overall protection of human health and the environment is greater for
Alternative 3 than Alternative 2.
2)
Compliance with ADDlicable or Relevant and ADpropriate Requirements (ARARs)
The ability of each alternative to meet all of its federal and state requirements that are applicable
or relevant and appropriate is noted for each alternative. The major ARARs for aU-I are
chemical-specific and action-specific, and are enumerated in Section J below. Table 7
summarizes the drinking water standards established by the Federal Safe Drinking Water Act
(SDW A) and adopted by the State of Minnesota for public water supplies. Maximum
Contaminant Levels (MCLs) and non-zero Maximum Contaminant Level Goals (MCLGs) are
the major federal ARARs for cleanup of groundwater at aU-I. Minnesota Health Risk Limits
(HRLs) and Recommended Allowable Limits (RALs) are additional to be considered (TBC)
criteria because they are intended to protect groundwater and present and future private well
users, respectively. The most stringent standard for each compound represents the
chemical-specific cleanup standard for that compound. .
.
Alternative I: The no-action alternative does not comply with ARARs or TBC guidance values.
There are currently 12 contaminants of concern in the groundwater at concentrations above
MCLs, RALs, and HRLs which would be left unaddressed in this alternative.
Alternatives 2 and 3: These alternatives provide for treatment of vacs using the existing
PGAC system and also include new facilities to remove iron and manganese thereby meeting all
of the water quality objectives for potable supply. Thus, treated groundwater will be in
compliance with ARARs. However, it is estimated that contaminants would remain in the
aquifer at concentrations approaching but still greater than MCLs, RALs, and HRLs for more
than 100 years.
3)
LoOI!- Tenn Effectiveness and Pennanence .
Long-term effec~veness and permanence are evaluated with respect to the magnitude of residual
risk and the adequacy and reliability of controls used to manage remaining waste over the
long-term.
Alternative 1: The no-action alternative does not provide long-term effectiveness and
permanence since the current interim treatment systems do not contain the entire plume and
private wells may be located in the plume pathway. TCE and other contaminants are currently
allowed to migrate towards the Mississippi River. As the plume migrates, the number of private
wells that could be impacted by the advancing plume potentially increases.
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Alternative 2: This alternative provides long-term effectiveness by removing contaminant mass,
providing an alternative water supply to residents with private wells located within the plume
boundary, and enacting drilling advisories that regulate the installation of new private wells
within the North Plume as a Special Well Construction Area. However, because this alternative
does not effectively contain the North Plume at any boundary, it does not provide a permanent
solution to the problem.
Alternative 3: This alternative also' provides long-term effectiveness by removing contaminant
mass and containing the plume, providing an alternative water supply to residents with private
wells located within the plume boundary, and enacting drilling advisories that regulate
construction of new wells within the plume boundary. Because this alternative effectively
contains the most contaminated portions of the North Plume in the vicinity of County Road E
it also provides a more permanent solution to the problem.
4)
Reduction of Toxicitv. Mobilitv. and Volume Throu2h Treatment
The assessment against this criterion evaluates the anticipated performance of the specific
treatment technologies included in the remedial alternative.
Alternative 1: The treatment systems currently in place (Le., TGRS, PGAC, St. Anthony
Municipal Water Supply) are moderately effective in reducing the volume of contaminants in the
groundwater. However, these systems do not contain the plume (Le., there is little reduction
in mobility).
Alternative 2: The mass removal alternative is designed to maximize the removal of
contaminant mass in the shortest amount of time. Based on computer modeling performed for
this FS, the mass removal alternative is predicted to remove about 83 percent of Ute mass of
contaminants in the groundwater within 30 years (Figure 7). Within 100 years, about 86 percent
of the contaminant mass is predicted to. be removed. This alternative is more effective than
Alternative 3 in reducing contaminant toxicity and volume, since it removes more contaminant
mass in less time. However, it is less effective in reducing mobility because it dQe$ not contain
the plume at any boundary.
Alternative 3: The containment alternative also provides removal of contaminant mass. As
shown in Figure 7, this alternative is predicted to remove about 68 percent of the mass of
contaminants in the groundwater within 30 years, and about 77 percent within 100 years.
Furthermore, because this alternative effectively contains the plume in the vicinity of County
Road E, it provides greater reduction in mobility than Alternative 2.
S)
Short- Tenn Effectiveness
The assessment' against this criterion examines the effectiveness of the alternative in protecting
human health and the environment during the construction and implementation of a remedy until
the response objectives have been met.
Since the only activity included as part of the No Action alternative (Alternative 1) is the
continuation of groundwater monitoring, it provides the greatest short-term effectiveness.
.Alternative 2 is the least effective in the short-term because it includes more extensive
construction activities than Alternatives 1 or 3 (more wells, longer lengths of pipeline and a new
15
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treatment facility). Alternative 3 provides a level of short-term effectiveness intermediate
between Alternatives 1 and 2.
6)
ImDlementabilitv
The analysis of implementability evaluates the technical and administrative feasibility of the
alternative and the availability of ~e goods and services needed to implement it.
Alternative 1: There is nothing new to implement with the no-action alternative.
Alternative 2: This alternative will be difficult to implement for the following reasons.
Alternative 2 would require three additional wells capable of extracting 750 gpm each,
generating approximately 2150 gpm (3.1 mgd) over a period of 50 to 100 years. The wells
would have to be located in a largely residential area, and easements may be very restrictive.
In addition, this alternative would extract more water than the New Brighton distribution system
can accommodate. Finally, because the City of New Brighton has concerns regarding the water
quality of any water coming from the Unit 3 aquifer, it will not accept this water into its
distribution system (i.e., the PGAC). Therefore, if Alternative 2 were implemented, 3.1 mgd
would have to be treated and disposed, for which no water management option has yet been
identified.
Another problem with this alternative involves its potential ineffectiveness for vertical
containment of the contamination. Existing municipal wells would be pumping continuously at
a minimum rate of 1335 gpm, making the total volume of water to be generated by this
alternative approximately 3500 gpm (5.0 mgd). Preferably, most of this water should be
extracted from the upper portion of the Unit 4 aquifer (i.e., the Prairie du Chien) to minimize
the potential of drawing contamination into the less-contaminated lower portioo (i.e., the
Jordan). However, the Prairie du Chien aquifer may not be able to sustain the pumping rates
estimated for this extraction scenario. This means that the pumping rates of some of the Jordan
wells will have to be increased, thereby increasing the potential of drawing contamination into
the Jordan aquifer, where it may spread further. .
. Alternative 3: The containment alternative involves installing two new extraction wells,
constructing a pipeline from the wells to the PGAC, constructing and operating an iron and
manganese removal system, and managing the excess water generated. The new wells for this
alternative would be installed near existing municipal wells, making their management easier.
The construction of a pipeline will also be readily implementable, since a 24-inch sanitary
forcemain currently located near the extraction wells and the PGAC can be used to convey the
water. Some easements for pipe runs that connect the extraction well to the main pipeline are
required; these are not expected to be difficult to obtain.
The current New Brighton water distribution system can handle a flowrate of 2,500 gpm from
the PGAC. This alternative produces about 2,200 gpm of treated water from the PGAC. No
additional water management options are required with this alternative. Most of this water will
be extracted from the Prairie du Chien aquifer, thereby minimizing further contamination of the
Jordan aquifer.
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7)
~
. "
The cost estimates for the three alternatives are" preliminary and approximate. The evaluation
against this criterion compares the capital costs and operating and maintenance (O&M) costs of
each alternative on a present-worth basis. The present-worth costs have been determined for 30
years at a 10 percent discount rate.
Alternative 1: There are no new costs associated with the no-action alternative. The U.S. Army
will continue to pay for O&M costs for the PGAC, which have been estimated at $450,000 per
year. Moreover, the Army will continue to pay the city of St. Anthony approximately $200,000
per year for the GAC used in its water treatment facility (for the first 10 years of operation).
The annual costs of continued groundwater monitoring have been estimated at approximately
$70,000. The estimated 3D-year present worth cost for continued semiannual groundwater
monitoring is approximately $726,000 (Table 4).
Alternative 2: The costs associated with this alternative include additional O&M costs for the
PGAC system, construction costs for the extraction wells and the pipeline, and construction and
O&M costs for the inorganics treatment facility. The total capital expenditure has been
estimated at approximately $4.6 million dollars and the annual O&M costs have been estimated
at approximately $900,000. The annual O&M costs include costs for both organics and
inorganics treatment. The estimated 30-year present worth cost for Alternative 2 is $14.2
Million (Table 5).
Alternative 3: The costs associated with this alternative include additional O&M costs for the
PGAC system, construction costs for the extraction wells and the pipeline, and construction and
O&M costs for the inorganics treatment facility. The total capital expenditure has been
estimated at approximately $3 million and the annual operating cost is ex~ted to be
approximately $700,000. The annual O&M costs for this alternative include costs for both VOC
removal and inorganics treatment. The estimated 3D-year present worth cost for Alternative 3
is $10.3 Million (Table 6).
8 & 9) State and Community Acceptance
These criteria reflect the state's and community's preferences among or concerns about each
alternative.
Alternative 1: The state and the community have expressed the need for additional remedial
action beyond the current interim actions in place.
Alternative 2: " This alternative may not be acceptable to the community (as represented by
officials of New Brighton) because they will not accept water from sources north of Interstate
694" into their. distribution system. Furthermore, they are concerned about the water
management problem involved with this alternative.
Alternative 3: State acceptance of this alternative is indicated by state concurrence on this
ROD. The community as represented by officials of the cities of New Brighton and Fridley has
strongly endorsed this alternative. Based upon comments received during the public comment
period, the community accepts Alternative 3 as the selected remedy.
"17
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I.
The Selected Remedy
The selected remedy for OU-1 is Alternative 3, the containment alternative. This alternative
includes providing an alternative water supply to residents with private wells with MDH drinking
water advisories within the impacted lone, implementing drilling advisories that would regulate
the installation of new private wells within the zone impacted by the contamination as a Special
Well Construction Area, implementjng a groundwater extraction scheme for plume containment,
pumping the extracted water to the PGAC, installing and operating an iron and manganese
removal system upstream of the PGAC carbon units, and discharging all of the treated water to
the New Brighton municipal distribution system.
CLEANUP STANDARDS
Following are the specific contaminant cleanup standards to be attained in the aquifer before the
remedy can be considered complete:
Contaminant
Cleanup Standard
p.g/L
Basis
1,1- Dichloroethane
1,1- Dichloroethene
cis-1,2-Dichloroethene
1,1, I-Trichloroethane
1, 1,2- Trichloroethane
Trichloroethene
70
6
70
200
3
5
RAL
HRL*
MCL, RAL
MCL
MCLG (proposed), HRL*
MCL
Other TBCs
Hazard Index for Carcinogenic
Mixture (see Table 7) S 1.0
Hazard Index for Noncarcinogenic
Mixture (see Table 7) S 1.0
HRL*
HRL*
. * Proposed Minn. Rules, Pans 4717. 7100 to 4717. 7800
The point of compliance will be along the containment boundary created by the combined
pumping of the existing New Brighton wells NB3 and NB4 and new extraction wells NB14 and
NB15, which groundwater modeling shows to be in the vicinity of County Road E. The area
of attainment is considered to be the areal and vertical extent of the North Plume. Groundwater
monitoring will be required until restoration of the aquifer is achieved.
Alternative 3 Win achieve substantial risk reduction by effectively containing the contaminant
plume in the vicinity of County Road E, while at the same time putting the treated water to its
most beneficial use. In addition, the North Plume will be extracted until groundwater cleanup
standards are achieved. The cleanup standards are based upon the ARARs identified for the
remedy and upon the HRLs as proposed groundwater cleanup standards and the Minnesota
RALS for private potable water supplies. Extracted groundwater will be treated to meet MCLs
. and non-zero MCLGs established by the SDW A. The most carcinogenic and pervasive
compound, trichloroethene, will be reduced to 5J.Lg!l or below, which corresponds to a 1.7 x 1~
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cancer risk. The State of Minnesota RAL will be the cleanup goal for 1, I-dichloroethane
because no Federal MCUMCLG exists for this compound. For cis-l,2-dichloroethene the
Minnesota MCL, the SDW A MCL, and the RAL are the same, 70 p.g/L. The State of
Minnesota HRL will be the cleanup goal for 1,1,-dichloroethene because it is more stringent than
the Federal MCUMCLG. The regulation of water well drilling by the State of Minnesota is the
institutional control to be used to regulate drilling of private wells in the North Plume before
cleanup standards are achieved.
"
Alternative 3 provides the best balance among the three alternatives evaluated against the nine
evaluation criteria. Based on the available information, EPA and MPCA believe that the
selected remedy is protective of human health and the environment, satisfies the remedial
objective of plume containment, is cost-effective, and utilizes permanent solutions to the
maximum extent practicable.
J.
Statutory Determinations
This section discusses how the selected remedy for OU-I meets the five statutory requirements
established by CERCLA.
Protection of Human Health and the Environment
The selected remedy will provide overall protection of human health and the environment
through extraction and treatment of contaminated groundwater. The extraction of the
groundwater will contain the most contaminated portions of the North Plume and prevent it from
spreading further. The extracted water will be treated to meet drinking water standards and
discharged to a public water supply. Institutional controls on the drilling of private wells will
help to regulate the installation of new exposure points within the contaminated areas at the site.
No unacceptable short-term risks or cross-media impacts will be caused by implementation of
the remedy.
Comnliance with ARARs
The selected remedy will comply with ARARs over time. The extracted groundwater will meet
the chemical-specific ARARs by undergoing treatment at the PGAC, while the action-specific
ARARs will be met during the construction, operation, and monitoring phases of the remedy.
The following is a list of ARARs and Wto be consideredw guidelines for the remedy:
Chemical-Spedfic
.
Safe Drinking Water Act, 40 CFR Part 141, Maximum Contaminant Levels and
Non-Zero Maximum Contaminant Levels Finalized and Proposed for
cis-l,2-dichloroethene, 1,1, I-trichloroethane, 1,1 ,2-trichloroethane, and
trichloroethene - Applicable for Discharge to Public Water Supply and Relevant
and Appropriate for Groundwater Restoration
19
-------
Action-Snecific
.
Mirinesota Recommended Allowable Limits, MDH Release No.3 (Jan. 1991), for
1, 1-dichloroethane and cis-1 ,2-dichloroethene - To Be Considered for Protection
of Private Water Supplies
.
Minnesota Health Risk Limits, in Proposed Minnesota Rules Parts 4717.7100 to
4717.7800 for 1,1-dichloroethene and 1,1,2-trichloroethane - To Be Considered
for Groundwater Restoration; Determination of Hazard Indices for Carcinogenic
and Noncarcinogenic Mixtures - To Be Considered for Groundwater Restoration
.
Resource Conservation and Recovery Act (RCRA), 40 CFR Part 268 Subpart D
- Regulates the disposal of spent carbon - Applicable
.
RCRA, 40 CFR Part 264 Subpart I - Requirements for tanks used for the
treatment of waste - Applicable
.
Minnesota Rules, Part 7060.0400 - Uses of Underground Waters - Relevant
and Appropriate
.
Minnesota Rules Chapter 4720, Public Water Supplies - Regulates community
and non-community public water supplies - Applicable
.
Minnesota Rules Chapter 4725, Water Well Code - Establishes well construction
standards and specifies requirements for designating Special Well Construction
Areas - Applicable
Cost-Effectiveness
The selected remedy provides an effective remedy proportionate to its cost. The degree of
. long-term effectiveness and permanence, reduction of toxicity, mobility, or volume of
contaminants, and ease of implementability afforded by this remedy give it a reasonable value
for its cost.
Jlti1ization otPennanent Sotmions and_Resource Recovery Technologies
to the Maximum Extent Practicable
The selected remedy meets the statutory requirement to utilize permanent solutions and resource
recovery technQlogies to the maximum extent practicable.
The selected remedy, Alternative 3, provides the best balance among the three alternatives with
respect to the primary balancing criteria. Alternative 3 provides a greater degree of long-term
effectiveness and permanence than Alternatives 1 or 2. Both Alternatives 2 and 3 provide a
reduction in toxicity and volume of contaminants. In addition, Alternative 3 provides the
greatest reduction in mobility among the three alternatives, and is less costly and easier to
implement than Alternative 2.
20
-------
Of the five primary balancing criteria, long-term effectiveness and permanence, implementability
and cost were the most decisive factors in the selection decision. By using the treated
groundwater in the municipal water supply system of New Brighton, the local contaminated
groundwater resource is recovered and the groundwater resource is conserved. Finally, the State
of Minnesota and the community support the selected remedy.
Preference for Treatment as a Prin~ipal Element
The selected remedy removes and treats VOCs in the groundwater using GAC. Therefore, it
satisfies the statutory preference for remedies that employ treatment as a principal element.
21
-------
Figure
-&
1
2
3
4
5
6
7
APPr-
LIST C
)IX A
"IGUR;;
Location Map
Conceptual illustration of TCAAP Operable Units 1, 2, and 3
Off- TCAAP Unit 3 Groundwater Contamination and Exposure Areas (As of 1987)
Off- Tr AAP Unit 4 Groundwater Contamination and Exposure Areas (As of 1987)
App nate Capture Zone for Extraction Scenario 21 (Hillside and Prairie du Chien
AqUlI;.- ;
Approximate Capture Zone for Extraction Scenario 23 (prairie du Chien Aquifer)
TCE Remaining - Alternatives Comparison
-------
Minnesota
MinnMpolis-St. Paul
Sourc* ModMM from AMI. 1968
N
TWIN CITIES ARMY AMMUNITION PUkNT
LOCATION MAP
FIGURE 1
-------
COUNTY ROAD C
-•—— TCAAP Boundary
Creek
Road
V71 OU-1 (Norm Plume)
OU-2 (Source Area)
OU-3 (South Plume)
TWIN CITIES ARMY AMMUNITION PLANT
CONCEPTUAL ILLUSTRATION OF
TCAAP OPERABLE UNITS 1,2, AND 3
Sourac Adapted from CRA. 1993
-------
l-r ~-i
(J J~ 11 N--1
:='CJ_\~ I r 1
. I I --> ..-.ua I
O! ~--11
! r--'.
--+-.-.-
.._---------_._----+----
--- --~- -- --- --- -
.
~dO
~=
v~
/;@i
c;::..
II
II
I!
TWIN CITES ARMY
AMMlNT10N PlANT
...
~.
tmJD;..
.. -,......-,_.---
..... ... a& ... ...
.. ----- -......
... ...
.. .....----
......... - ---
.-..-......-
.---....--
.-
.-
-..
SCAU: .. - J.JII1Ir
-----.
- - .----
'XJRCE USEPA. 1"1
---------.-----..--
--'------
il
~
I
----I
- +- ---+" --
~ ---.-
'WIN ell" S AlIY'f AUUUNIlIOH PlAtH
OFF.TCMP UNIT 4
GROl/NOWA IER CONTAII'NA nON
AND EXPOSURE AREAS (AS OF 1881)
f K;I"tf- ..
-------
VALENTINS
USX '
TWIN CITIES ARMY
AMMUNITION PLANT
TCC Concentration
in ports p«r btfun
(it no numfav (•
cancantrollon not
1. TCE Plum
b» U.S EPA. U.S. »im».
and tM«r can«*Hant» 0
5 k «. 1990
NEW
BRIG'n ON
IWNCIIPf 5 AftU»*MUUM)riOHPLANt
0( F TC»*P UNIT 3
r.HOIINnWHEH COHI»UIN»TIOH
AND ( XPOSUOF AREAS (AS OF 1M
-------
Twin Cities Army
Ammunition Plant
_._._ site Bouidwy
CiMk
100—-
TWIN CTHES ARMY AMMUNITION PLANT
APPROXIMATE CAPTURE ZONE
FOR EXTRACTION SCENARIO 21
(HILLSIDE AND PRAIRIE
du CHIEN AQUIFER)
-------
K.~k.
~
A
SuIliv8n:l.;u.
~
I
I
I
I 1
II 1
c9:
~
~
LJ8I Uit'*'--
v
,
\
\
\
\
\
, \
coUNTY ROAD C ,
I \
\
LEGEND: ,
51f8 BowtdaIy {\
CrMk
-100-. TeE I8ocanc8ntrallan
UnI (JIfU, dashed whirl ir8r8d
R08d
. ExhcIton w.. LocaIIan a 2ODO ...
'- Pr8dic;f8d CaDan Zone ' ,
SCALE .. FEET
.
'-",j1.M8
"
~
. ~IMI"SON
~
Source W8fICIC. 11182
'TWIN ane:. . PII'I AMMUNIT10N PLANT
APPROXlll#. ';: CAPTURE ZONE FOR
EXTRACTION SCENARIO 23
(PRAIRIE du CHIEN AQUIFER)
FIGURE 8
-
.. ;,..r.; ~.~
.,
.~~
..
.. .
-------
;e
-c;; 70
c:
:s
CD 60
E
CD
a:
w SO
(.)
...
1 40
ii
'3
e 30
~
(.)
. \._:.a;::-'
100
90
80
20
10
o
PGRS-1000
o
10
20
LEGEND
.
c
SCZ3 (AII8matM 3)
SC21 (A1t8mdY8 2)
Soutce: ETA. ,.
.. ,.~t:..
-tot,'"
30
-40
50
Time (years)
.-
60
70
80
- 100
90
. ....-rGCI1_'Y~
1WIN cmes A1NY AMMUNmON PLANT
TCE REMAINING -
AL TERNAT1VES COMPARISON
RGURE7
-
.'.~
-------
Table
~
1
2
3
4
5
6
7
APPENDIX B
LIST OF TABLES
Summary of Risks for Exposure to Off- TCAAP Groundwater, Probable and
Reasonable Maximum Exposures, Current and Probable Future and RME Future Land
Use Conditions .
Summary of Technology and Process OD!:ions Screening
Potentially Feasible Treatment Technolo~. 'and Process Options
Cost Estimate for Alternative 1: No Acti,_,.. :\lternative
Cost Estimate for Alternative 2: Mass Removal Alternative
Cost Estimate for Alternative 3: Containment Alternative
Drinking Water Criteria/Guidelines for Public and Private Well Supplies
-------
TABLE 1
SUMMARY OF RISKS FOR EXPOSURE TO OFF-TCAAP GROUND WATER
PROBABLE AND REASONABLE MAXIMUM EXPOSURFS
CURRENT AND PROBABLE FUTURE & RME FUTURE LAND USE CONDITIONS
(Page I of 4)
&- c.no.
E..-n ..... AI:IuII8 ttIwwd ...... 0wanIa Hu8nt ....
Mef'N .,...., &r-- ........ 0...- AIWI a...- AIWI
1ng..1Ioft ob 4E-OI 3.7E.o:I 1.3E-03 3.7E-03 . .31:-0.1
---~-- ----J@ir--- ---y..u--- ---j~((M--- ---y~~--- ---3:4t'"M---'
15 inhalation ob 2E~7
lkIll i ---~--- ----2@.---- ------------ ------------ ------------ ------------
o..mal Ptobable IE-OI 3.IE.o:I 1.1E-03 4.0£-03 2.1E-03
ConI8Ct ---1111--- ----H~r--- ---TorS--- ---.:fr.iJ--- ----firM--- ---i:2r"M---
TOfN.. ---1IM'--- ----!@1»i----
1ng..1Ion 4 -G8
---1111--- ----)I!.----
3V Inhalallon -G8
lkIU ---1IIl--- ----U~----
Dermal -G8
Conl.ct ---16Ii--- ----~..----
101M. able . -415
---lUl--- ----iE:oi---- -----~----- -----r10-----
4 -G8 U -03 2. -03
Ing..don ----J@:oi---- ---TIir.or-- ---i:o£'M ---
3W 2 .oe U -44 '.4 ~
lkII13 Inhal.1Ion ----2E~---- ---1f.fr-M--- ---1::'1"-0(---
De,mal 6 7. -03 31 -03
Conlact ----u.---- ---j:i(-M--- ---u1".or---
1 1 -415 NO NO
---ml--- ----il::04---- -----Nfr---- -----NI)----.1 -----NI)----- -----r10---_l
SOURCE: USEPA, 1991
-------
TABLE 1
SUMMARY OF RISKS FOR EXPOSURE TO OFF-TCAAP GROUND WATER
PROBABLE AND REASONABLE MAXIMUM EXPOSURES
CURRENT AND PROBABLE FUTURE & RME FUTURE LAND USE CONDITIONS
(Page 2 of 4)
.....
,..,.". ..... E.J II -
1118111" n ~~-_.
ax ,,-.',1IR ~r'1Ur~
IWU
........ .<~~:~
ConIM8
~'.:. ~~~"'r"
"
~'''Dft ."~11117.
av ~...,.~ --~1UI7".
IWU
0...... ~"":1111~~.
c..e.e
Nf~' ..
.~~~~:"~.
Ina ..111ft ---11117.'
II I""''''''~ _.-1111~".
IWU
D8fmII ~--?1111~-"
CaftIM8
1OfM.'
---lW---
.:- c...
.... -- ...... ...... 0IIanID ...... ......
....... C»tI' AIUI a...- AIUI
.. .. .oz 3. .oz
--"-11!~---- ---.....ar--- -"-i:3T4i'-"
t .. 4. ~ 7. .
----1'](-61--- ---UT4'(---
1.4 .oz 4. .oz
---.:.~n--- "--UT.4fr"--
7~~-~~---
~
."~.Jla"~~-
-'"7"-8.----
-"~-~«I.~"~
t
.""-lI,ijt-..--- -----,..-..--- ---.-fl)-"-"" """""r6"-"-- -----116-----
. ...
""-fJliW--
----u:o;----
.oJ
----lr.----
-----~----- -----H~-----
-----Nb----- -----Nft-----
. .
-------
T A&lLlE 1
SUMMARY OF RISKS FOR EXPOSURE TO OFF-TCAAP GROUND WATER
PROBABLE AND REASONABLE MAXIMUM EXPOSURES
CURRENT AND PROBABLE FUTURE & RME FUTURE LAND USE CONDITIONS
(Page 3 of 4)
~..
IftaJtN ....... t.,U.IN
~ ---111(---
4W Inhale*-
UnII 4 ---1Iil---
0If- Plob'"
ConI8GI --"1IK---
'UJIIL ........
---liK---
.... ---1iIl---
4X lnh8Ialion Probable
Unll4 ---1ii~---
OIfmal Probllble
ConIace ---liII---
10 M..
---1iIl---
Ingaallon Probable
---~---
4Y inhalation Probable
UnlI4 ---liII---
De,mal Plobable
Conlad ---1Uf---
TOTIIL Probable
---1Ui~---
&- c.no.
....
ftIaIdanI
2£-
----11:0.----
IE-G5
----'il~----
I E-G5
----il~u--
4E-G5
----:il~----
IE-
----i~~----
IE.-
----if.-_u
3E.-
_u-ie..----
IE-
----il~----
2E-G5
--u:if.----
1 E-G5
-u-n.----
3£ -G5
u--i~4iuU
IE.
_u-2E~_u-
-- ......... bIc88
0IIId" AduII
8.IE.o1 3.2E.o 1
---i~irir-u ---"4":"ilii---
NA NA
-----NA----- -----~-----
1.1£.02 ..3E~
---i~ir"M-u _u"3":"ilii---
NO NO
-----iiJ----- -----"0-----
8.01: . 00'" 2.2E.00-
---..if.iiO"-- u-iiif.oo"u
NA NA
-----ilA----- -----NA-----
t.IE.o1 1.0£-01
---"3":"i{iiU- uUI:iEii-u
NO NO
-----fl)----- -----N()-----
t.5E.02 5.4E~
----:f feM--- uUI:ciEii-u
NA NA
-----m----- -----N1-----
t.'E.02 82E~
-Uj-:-iE.Oru ---TiE.or--
NO NO '
-----"0----- -----"0-----
0waN0 HuaId bIc88
a...- AduII
I.3E.oI 3 OE--OI
---.-or.or--- ---nE~f---
tOE .03 1.8E.o.t
---Yi{ij--- u-l1E~u-
3 0£--02 1.8E--02
---Tf{.oi--- ---j:Jl".ozu_-
NO NO
-----N()----- -----;;0-----
87E.00- 2.4.00'"
_uiif.o.y-- --j-:-ii[.wr--
UE-m 1.7E--04
---.:«-ii -u u-nl".«Ju--
2.4E.oI 1.3E--01
_u"4":"«-ii-u ---i3E~f---
NO NO
-----Nb----- -----NO-----
21E.02 UE~
u-"3-:-i(iiU- ---UE&-u
UE~ UE--04
---.:2(-ii--- u-nE~----
UE.02 2.3E.o2
---,:iE.oru _u3:oe~u-
NO NO I
-----"0----- -----riio-----
-------
T ha.....E 1
SUMMARY OF RISKS FOR EXPOSURE TO 01' I'.. fCAAP ft ., OUND WATER
PROBABLE AND REASONABLE MAXIMUM EXPOSURES
CURRENT AND PROBABLE FUTURE & RME FUTURE LANO .'SE CONDITIONS
(Page 4 or 4)
(J I"
,..,... ~ 81 W
~1I1I1R .~----
. ;':':~ .
,
'4 ...... . d 1 ...~-.-.
UnII 4 ...,::: .;":
DMuI ~~~...
0InI8III8
, -,utili. .
~ ..~.._:~
~--
, ..:A
-- ............
0IId"
MIl
-G4
-~-"'lli"'---
-G4
-~"-1rM----
.. ::-r=
2t:4H
-""-11.----
-----~--~--
-----Ii6----- .
Qna8IIa Hun hIDee
0IId"' MIl
Ut(::~ 4.7EfH
---ill., ----i*~f---
UE-G2 3.0E-G.1
----ftWlijU - ---ri17cif---
IL UE-GI
---ril.w-- ---i~..r.of---
NO NO
-----(6----- -----;ul-----
-------
TAB.
SUMMARY DFTECHNOLOGY AND PROCESS OPTIONS SCREENING
Result or
Treatment InUbl
TechooIOU MedinDes.I ImpltlllwtabUUy Cost Scrttnlna: Comments
IINSTITlITlONAL CONTROLS
OrOl8ldwaa Mooitcriaa N- l!uy ModcJate EtimiDate Exltllsive groundwaeer mooiloring program exists
Altenadye Weta' Supply (a) NmM Modenl. Low Cuoolder IndudN woatdered lur further evaluatlun
-------
TABLE 3
POTENTIALLY FEASmLE TREATMENT TECHNOLOGIES
AND PROCESS OPTIONS
General Response Actions
TechnologieslProcess Options
Institutional Controls
Alternative Water Supply
Drilling Advisories
Remova1/Extraction Options
Scenario 21
Scenario 23
Groundwater Treatment
Liquid-phase GAC,
OxidationlFiltration
Water Management Options
Municipal Usage
-...---.-'.--------"----------'---- - -- -.--.. ------- ... -".. -
-------
TABLE 4
COST ESTIMATE FOR
ALTERNATIVE 1: NO ACTION ALTERNATIVE
ItemlDescription
Quantity
Unit
Unit Cost (S) Total Cost (S)
ANNUAL OPERATING AND ~ANCE COSTS
Continued Groundwater Monitoring Program (semiannually)
Sample Collection and Analysis 2
Consultin g and Reporting services
per year
lump sum
S50.000
$20.000
510.000 I
TOTAL ANNUAL COST
PRESENT WORTH
Interest Rate
Years
I~
30
5126.0001
TOTAL PRESENT WORTH
-------
--.. ---.... ----
TABLES
COST ESTJMA TE FOR
AL TERNA TJVE 1: MASS REMOVAL ALTERNA TJVE
ItemJDescription
Quantity
Unit
Unit Cost (5) Toea! Cost (5)
10 each 522.500 $225.000
lump sum 5IS.000
3 each 580.000 5240.000
IS.840 each 54 563.360
IS.840 feet 520 5316.800
I each 520.000 520.000
200 each 51.500 5300.000
20.000 linear feet 51S $300.000
1 each 58S.OOO 58S.OOO
2 each 512.000 524.000
S each 580.000 S4OO.000
I each 510.000 510.000
2 each 53.500 $7.000
Toea!lnorganX:s TraUDent EC 5526.000
5151.800
5210.400
552.600
552.600
S.OOO sqare feet 5100 SSOO.OOO
1 lump sum $70.000 $70.000
53,049.560
$304.960
5518.430
$762.390
I 54.635.340 I
CAPITAL COSTS (CC)
.'
Additional GroundwaIeI' Monitoring
Well Drilling and Installation
Preparation of Monito"ng Plan
Extraction Wells
Conveyance System to PGAC
Inspection/cleaning
Pipeline Installation
Pump
Alternative Water Supply
Abandon Pri vate Wells
Hook-up to Municipal Supply
Inorganics Treatment
Equipment Costs (EC)
influent surge tank
Ir.I/1Sfer pumps
greensand filters
KMn04 storage tank
chemical feed pumps
Installation (30~ EC)
Mechanical (4O~ of EC)
Electrical ( I O~ of EC)
Insaumelltation (1 ~ of EC)
Building Costs
Site Preparalion
SabtoC8l C-a...cdoG CoAl (CC)
Engineering Design (I ~ of CC)
AdmiDistratioo Costs (17~ ofCC)
Contingency (2S~ of CC)
ANNUAL OPERATING AND MAINTENANCE COSTS
TOTAL CAPn'AL COSTS
ConIiDtIcd GIOUIIIIwater MoaicoriDl PropIIII (-;..........,)
Sample Collection IIId ADalysiJ 2 per Ye8'
0-......, aDd Repnrtinl ScrviceI lump -
Ad11i1a81 GtoaDdwIlllr Moaicarina I'rap8m (sam-Jly)
S8DpIc CoIIecIiaa IIId ADaIyIis 2 per yaI
C-!titIa1lld Rcportina Semces lump SIIII
I8qIIIiI:a TraIIDCIIt (Fe .t Mn remO¥8l)
L8bar
I!acrv
0aaicIIs
I
580.000
6.p' ~ 1. MIl "MII"'- e
MoairariD8
AddiIi~ 0rpIIics TraIIIIeIIC (PGAC at 3.585 IJIIII)
Carboa CbIm.-a 213.300
0IemicaII
~.;-
Labar
-Je8'
tw...
lump .-
2~ of EC
lump-
pounds
lump -
lump -
-Ye8'
PRI'SENT WORTH
TOTAL ANNUAL cosr
SI00.ooo
$0.10
$98.000
.SI.50
SIO.IOO
56.800
SIOO.ooo
S46.000
S 15.000
548.000
S 15.000
S 1 00.000
$58.000
598.000
SI05.200
S2.5OO
5319.950
SIO.IOO
56.800
SI00.ooo
5924.5501
IIIIeraIIbIe
Van
TOTAL PRESENT WORTH
10..
30
I SI4.200.0001
-------
TABLE 6
COST ESTIMATE FOR
AL TERNA TIVE J: CONTAINMENT AL TERNA TIVE
IlemlDescription Quanory Unil Unil COSI (S) TOI8I Cosl (S)
CAPrrAL COSTS (CC)
Additional Groundwater Moniloring
Well Drilling and Installation 10 each S22.500 S22.S.ooo
i) Preparation of Moniloring Plan lump sum S15.OOO
Exll3Ction Well each $80.000 S80.OOO
Conveyance Syslem 10 PGAC
Inspection/cleaning 5.280 each 54 S21.120
Pipeline Installation 5.280 feet S20 SI05.600
Pump I each 520.000 S2O.OOO
Ahemative Waler Supply
Abandon Privale Wells 200 each SI.5oo SJOO.ooo
Hook-up 10 Munic:ipaJ Supply 20.000 linear feet 515 S3OO.OOO
Inorganics Treaunenl
Equipmenl COSIS (EC)
influenl surge wUc I each $85.000 S85.OOO
tr.IIIsfer pumps 2 each S12.OOO S24.OOO
greensand fillen 2 each $80.000 5160.000
KMn04 slorage wUc I each SIO.ooo SIO.ooo
c:hemic:al feed pumps 2 each S3.500 51.000
TotaIlDorpnic:s Trealmall EC 5286.000
Installation (30' EC) $&5.800
Mechanical (~ of EC) 5114.400
Elecuical (10.. of EC) 528.600
lnslNlllCllWiOll ( I 0-. of EC) 528.600
Building Coscs 3.000 squII'II (eet 5100 S3OO.000
Site Prepruatioa I lump sam 570.000 570.000
SublDtlll c-crucdaa CollI (CC) S 1.980.120
EnginceriDg Design (10.. of CC) SI98.010
AdmiaisUUioo Casu (17.. of CC) 1336.620
Contingency (25.. 01 CC) 5495.030
TOTAL CAPITAL COSTS I SJ.009.780 I
ANNUAL OPERATING AND MAINTENANCE COSTS
Continued GftIUJIdwucr Monilorinl Prop8m (semiamtuaIly)
Sample ColIeaioa IIId Analysis 2 peI''''
CoaIII1tiD8I11d Reponinl Scm8 Iamp-
AddiIiaal1 a.......d..- MoniIariD8 PIvp8D (,....i........lly)
Sample ColIeaioa - Analysis 2 pel' yar .
0--..,- JteponiDg Scmc:a !tap sam
r-..mca TraIIDaII (Fe .t MIl raIIII¥II)
LIbar
EmrI7
0IaaiI:ala
ecpr-'" .
MCIIiIDriIII
, AddiIiaaIl Orpaica TtaIIDeIII (PGAC . 2.250 gpaI)
Cuboa 0IqaIIII 1$8.000
0IaaiI:ala
MaiI:t-
S46.OOO
515.000
$48.000
51'.000
1
420,000
-,..
tw-IIr
--
~oIEC
--
5100.000
$0.10
133.000
5100.000
S42.OOO
133.000
SS7 .200
S2.SOO
Labor
.-.
lamp sam
hap sam
-,..
51.50
S6.2OO
S2.8OO
5100.000
S237 .000
S6,2OO
S2.8OO
5100.000
S704.700 I
TOTAL ANNUAL COST
PRESENI' WORTB
IIaIat R.-
Yan
1"'
JO
TOTAL PRESENI' WORTB
I 510.310.0001
-------
TABLE 7
DRINKING WATER CRITERIA/GUIDELINES
FOR PUBLIC AND PRIVATE WELL SUPPLIES
CompoUDd
Ma.~LDD
Contam:...lnt Lenl
(MCL) (j.&g!1)
Recommeaded
Allowable LimIt
(RAL){j.&&I1>
.ah
- Limit
....U-)v.&I1)
1,l-Dichloroethene
7
70
6
6
1,l-Dichloroethane
cis-l,2-Dichloroethene
70.
70
600
1,1.1- Tric hloroethane
200
Trichloroethene
5
3
30
3
1,1,2- Trichloroethane
5.
Hazard Index for Carcinogenic Mixaues
See Note 4
Haza.rc :dex for Noncarcinogenic
MixDlrcs
See Note 5
.
Proposed MCL.
Does not exist
Notes:
1. Maximum contaminant levels are specified in the Primary Drinking Water Regulations (40 CFR 141).
2. Recommended Allowable Limits are specified in Release No.3, Minnesota Department of Health. lamwy 1991.
3. Health Risk LimitS are proposed values as of April 19, 1993.
4. To determine if the bealth risk limit for a mixDlre of carcinogens is exceeded. a hazard index must be calculated using the foUowiDa
procedure (Minnesota State Register. Proposed Rule 4717.77(0):
A. A hazard index sball be determined for subStaIICes or chetnicals with a toxic endpoint of cancer as specified in Proposed Rule
4717.7650 using the foUowing equation:
Ha:ztlrd index =
Ec
I
HRLc
I
+
Ec
%
HRLCz
.
+ ----- +
Ec
.
HRLc
.
wbere:
(1 ) Eo:. reprc'
(2) HRLc. re~:
4717.7~.
:be concentr.
.IS the beak
of lite fll'St, second, ... nth carcinogen detected in gl'OWldwater; aDd
- limit of lite fll'St, second, ...nth carcinogen as specified in Proposed Rule
B. A bazard index of oae iDdicaII:a 8 lifetime risk level of oae in 100,000.
C. A bazard index of ODe ea\Ws the bealth risk limiL
D. A haz;; iDdex IIIIIer C 0lIl ucecd.s Ibc heallh risk limiL
s.
To detcrmiDa it 1bI1Ialda risk limit for 8 mixlW'e of SYStemic toxicanls is exceeded, a bazanI index must be calcul~
foUowiDa p....Adwa (MiaDaota SIIIe ReaiStcr, Proposed Rule 4717.77(0):
'iinI the
A. 'Ibe su""'- 01' .-.-...1. cIeIIectcd in the ,l'OWIdwater must be grouped by toxic endpoint as specified in Proposed lWIe
4717.7650,
B. WheD tWO or more sub-- or chemicals ~ave the same toxic endpoint, a hazard index must be deImniDed for each group of
substIIICCS or ch=~ willa the same toxic; '1point using the foUowina equation:
Ha:ztl7d index =
-ST.I
HRL~
I
+
En:
%
HRLn:
%
+ ----- +
EST.
.
HRLST.
.
where:
(1) E.,.. rep~ the concentration of the fll'St, secol1l1, ... nth syStemic toxicant detected in IfOUndWller, aDd
(2) HRLn. represeDlS the bealth risk limit of lite fll'St, second, ... nth syStemic toxicant as specif'1ed iD Proposed Rule
4717.7500. .
C. A bazard index of ODe equals the bcalth risk limiL
D. A bazard index ,reatcr than ODe exceeds lite bealth risk limit.
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