United States
Environmental Protection
Agency
Office of
Emergency and
Remedial Response
E PA/ROD/R05-87/058
September 1987
SEPA
Superfund
Record of Decision:
New Brighton/Arden Hills/TCAAP,
MN
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TECHNICAL R EPOAT OA T A
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EPA/ROD/R05-87/058
..1'11'1.1 AIIIO SYITI1'I.I '5 IIIU'OIilT OATI
SUPERFUND RECORD OF DECISION September 25, 1987
New Brighton/TCAAP, MN 8. ~EIII"Olll-"'I"'C OlllC"""ZATION COOE
Th i rd Remedial Action --
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12. 5"ON501ll1NG AGINCY NAMI ANO AOOIilISS 13. TYIt. 0" 1111"01111' ANO "1111100 COIIEI'IEO
U.S. Environmental Protection Agency Final ROD Report
401 M Street, S.W. 1.. 5"ON501ll1NG AGINCY COOl
Washington, D.C. 20460 800/00
15. SU"~I.IMINTAIilY NOTIS
". AUTIilACT
The Twin Cities Army Ammunition Plant-(TCAAP) is located north of the Twin Cities Of
, Minneapolis/St. Paul, Minnesota and comprises the northern edge of the New
Brighton/Arden Hills/St. Anthony (NBAHSA) Superfund NPL site. Fourteen identif ied."
source areas exist in the TCAAP and three sites are expected to be the source of VOC
contamination emanating from the southwest boundary. The U.S. Army estimates
approximately 26 pounds per day of VOC contaminants are migrating off TCAAP into the
ground water at the southwest boundary of TCAAP. This contamination is migrating i'n
both the Hillside Sand Aquifer and the deeper Prairie du ~hien/Jordan Aquifer (both are
aquifers that supply water to the cities of New Brighton and St. Anthony). Both of
these cities have made modifications to their water supply due to ground water
contamination. From 1982 to 1984 various municipal wells were deepened, shut down-or
had carbon filters installed. Several private well users adjacent to the TCAAP site
were connected to city water supplies. Three previous RODs for the NBAHSA site have
recommended an additional well for New Brighton from an alternate aquifer, carbon
treatment for two of St. Anthony's wells and construction of a Boundary Ground Water
Recovery System (BGRS) to intercept the contaminant plume. This operable unit source
control ROD addresses operation of the BGRS, collection of operating data in order to
evaluate the system and modification of the system, as necessary, to ensure in tercept io
(See Attached Sheet)
17. KIY WO"OI ANO OOCUMINT &NAI."'II
a. OIIC"'I'TO". b.IOI"'1'III'IIIIIIO"I'" INOIO TIIilMS C. COSATI FlCldlGICNp
Record of Decision
New Brighton/TCAAP, MN
Third Remedial Action .
Contaminated Media: gw ..
Key contaminants: VOCs, PCB, heavy metals
( lead, arsenic, chromium)
'I. OISTIIIIIU1'ION ST&1'IMINT " SICUIilITY Ci.AU / TlIII R,ponl ~1 NO 0" ""CIS
None 75
~O. SICylillTY CI.ASS, 1"7111 pop, 2Z ~""CI
.
I'~ ,- 3120.1 (R.... ..71)
"..""01.11 801""0" II 0'10...8"'8
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EPA/ROD/ROS-87/0S8
New Brighton/Twin Cities Army Amunition Plant, MN
Third Remedial Action
16.
ABSTRACT (continued)
of contaminated ground water in the two affected aquifers. The primary contaminants of
concern affecting the ground water include: PCBs, benzene, toluene, TCE, VOCs, arsenic,,/
chromium, lead and metals. .
The selected remedial action for this site includes: operation of a six-well system
to extract ground water migrating from the southwest corner of TCAAP and treatment with
air stripping. Approximately 300,000 gallons per day will be utilized for in-plant use
with the remainder disposed of by reinjection/infiltration through the arsenal sand and
gravel pit; evaluation of operating data and monitoring results and implementation of-
any additional measures required to capture contaminated ground water migrating from the
site. The estimated capital cost for this remedial action is $4,000,000 with annual O&M
of $120,000. Additional capital ex~enditures may occur if modifications to the system
are ~eeded to achieve adequate water quality.
H
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Record.of Decision for Gradient Control Syster.!
SITE:
Twin Cities Army AMmunition Plant (TCAAP) New Brighton/Arden Hills;
Ral'1sey County, Minn.esota: a portion of the Nat.ional Priorities
List Site, New Brighton/Arden Hills/St. Anthony
DOCUMENTS REVIEWED
The. fa 11 owi n9 document s hav!=! been rev i e'fJed:
- SlIl'1mary of Remedial Alternatives Evaluation (attached)
- Responsiveness SUl'1l'1ary (attached)
The U.S. Army Record of Decision dated May la, 19~7 and supporting
documents. .
- The U.S. Army Record of Ueci sion dated July Hi, 19~7 and
sup~orting docu~nts.
DESCRIPTION rF SELECTEO RE~1Ef)Y
.
- Operation of a groundwater extraction system using existing wells
with possible expansion of the system as required for the protectl0n
of hunan health and the environl'1ent in both the Prairie du Chien/
Jordan and Hillside Sand Aquifers.
- Extraction of contaminated grrnJndwater for hydraulic yradient control
at ~he S~hwest houndary of the TCAAP.
- Contaminated groundwater wi llbe treated to meet discharge re-
qui rements.
-
-"Prior to 15U day~ after startu~ any modifications required to
adequately protect both the Hillside Sand and Prairie du'Cllien/
Jordan aquifers will be evaluated using the data collected i~ the
first 90 days and submitted to U.S. EPA and MPCA.
- 150 days after U.S. EPA and MPCA determine the proposed modifications
to he consistent under Part XIV of the 1tAAP Federal F acil i ty Ayr~ement,
the modifications will be constructed and oper~ted.
DECLARATIONS
Consistent with the Comprehensive Environmental Response, COMpensation and
Liability Act of 1980 (CERCLA), the Superfund Amendments and Reauthorization
Act of 19~6(SARA), W the National Contingency Plan (4U -cFR Part 3UO), .1
have determined that tRe immediate operation of a yradient control sy~tem
(a hydraulic plume intercept-ion system) which meets estahlished performance
criteria will assist in t~e_protection of public health, welfare, and the
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environ~p.nt, and is an operablp. unit consistent with future remedial actions.
The systeM will require continuous future operation and maintenance efforts
and expense for an indefinite tir.-e period. The U.S. Army has agreed in a
Fefferal Facility Agreement-to .the operation and maintenanc~ of this system
for an indefinite period to he determined by the U.S. Environmental Protection
Agency (lI.S. EPA) and Minnesota Pollution Control Agency (MPCA) pursuant to
the Federal Facility Agreement. This document records decision on a gradient
control system to prevent ~igration of VQC contamination i~ groundwater first
proposed hy the U. S. 'A rmy 0 n May 10, 19~7 and resubmi tted in mod.ifi ed fo rm on
June l~, 19~7. This Record of Decision (ROO) includes changes made. by u.s. t"YA
to the proposals stibmitted by the Army on May la, 19~7 and June l~, 1~~7.
"
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Since the public COf'1ment version ~f the U.S. Amy ROD was .made available on
May 10, 1987 an Agreerrent wi th .the U. S. Army has been reached. The TCAAP
. Fefferal Facility AgrePment (Agreement) will becOf'1p. effective soon after the
end of the puhlic comment period on the Agreement. All appro~riate submittals
anrl actions undertaken to imple~ent this Record of Decision will be in accord-
ance with the terms of the Agreement. The Agreement requires proposals by the
U.S. ArT'1Y for Roundary Gradient Control Systef'1s. The U.S. EPA is obligated
under that Agreement to inform the U.S. Amy of requirements 'for an acceptable
proposal. The description of thp. chosen alternative in the attached Su~ry
of Remerlial Alternative Selection describes tile requirements of an acceptabl~ .
plan.
The ROD concurs with the use of the remedial technology selected and system
constructed hy the U.S. Army at TCAAP for gradient control as set forth in
the U.S. Amy proposals dated May 10,1987 and June 18, 1~87. .
However, this ROD does not fully concur with the plans submitted by the
U.S. Amy with r~p.ct to operating requirements for tile gradient control
system, specifically: capture criteria to determine adequate }nterception,
o.f the migrating contaminants, discharges, emissions, and the schedule for
i~plementing any necessary modifications to achieve adequate interception
of the ~igrating contaminants.
This Record of Decision thus formulates the process by.which the existing
circumstances, independent actions and existing hardware can be utilized
in the most expeditious manner to ~revent further migration of contaminated
grounrlwater fro~ the Southwest boundary of the TCAAP. This ~ecord of Deci-
sion for a gradient control system ~onstitutes a final plan within the meaning
of 117 (b) of CERCLA/SARA.
d
The State of Minnesota, through the MPCA, in conjunction with the U.S. Army
is continuing its comprehensive. Remedial Investigation (~I) for the entire
New Brighton/Arden Hills/St. Anthony study area. The ~PCA will finish the
regional RI and the IJ.S. Army will perform the on-TCAAP RI and the Site (area
wide) Feasihility Study.
. .
The MPCA has already"~pl~ted a preliminary Remedial Investigation character-
izing the site, major migratiqn pathways, and preliminary identificati.on of
signi ficant sources. The t1PCA and the U.S. Army are planning to ccrnp~ete the
refTlaining tasks of the ccrnprehensive RI/FS in 198~-89 in order to evaluate po-
tential final remedial actions. If addition,l re~edi~l act~ons are determined
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of Decision will be prepared for approval of the
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Jiffi;.,!,er is 119f1
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ATTACHMENT 1
SUMMARY CF REMEDIAL ALTERNATIVE SELECTION
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ATTACHMENT 1
. SW'1~ARY a= REMEDIAL ALTERNATIVE SELECTION
Site Location and Description
The New Rrighton/Arden Hills/St. Anthony Superfund National Priorities List
(NPL) site is located north of the Twin Cities of Minneapolis/St. Paul, ~1innesota.
This site includes the f11ajority of the New Briyhton Quadrangle, which includeS
parts of Anoka, Hennipen and RaMsey County.
The Twin C'ities Army Af11Munition Plant (TCAAP) is located at the Northern edge
of the NPL site. Fourteen identified source areas exist in the TCAAP and three
(3) sites (0, r" and I) are expp.cted to be the source of VOC contamination
emanating frDr1 the' Southwest boundary. The U.S. Army estimates 'alJproximately
26 pounc1s per day of VOC contami nants are mi grati ny off' TCAAP in the yroundwater
at the Southwest houndary of TCAAP. This contaMination i-s miyratiny in both
the Hillside Sand Aquifer and the deeper Prairie du Chien/Jordan 'Aquifer. ,
The U.S. ArMY currently has six wells in the Hillside Sand Aquifer estif11ated
to be capable of interception of VOC contaminants in the groundwater.
.
Site History
Roth the Cities of New Brighton and St. Anthony have had to Make I'1Odi fic.a-
tions to their water supply systems due to groundwater contaminati~n.
From 19a2 to 1984 the City of New Brighton shut down six wells (wells one
to six).in~the lliirie .du Chien/Jordan aquifer. deepened two wells (e and
9) to the Mt. Simon-Hinkley aquifer, and constructed three new wells (la,
11, 12) in the Mt. SiMon-Hinkley aquifer. In 1983 the U.S. EPA installed
carbon filters on two New Rrighton wells (5 and 6) to meet summertime peak
demands.
nuring 1983 a State-lead InteriM Remedial Measure connected several private
well users adjacent to ltAAP with excessive contaminant levels in their wells
to New Brighton's and Arden Hills' water mains.
In 1984 the City of St. Anthony received a teMporary water connection to
the,City of Roseville as a State-lead Int~im Remedial Measure. This
Measure was necessary due to the water shortage experienced by St. Anthony
due to contamination and subsequent closure of one of the three St. Anthony
wells in the Prairie du Chlen/J9rdan Aquifers.
Current Site Status
'A Record of DecisionJ!c1s' signed on Junp. 30, 19H6 by U.S. EPA .to provide New
Rrighton with an addit",~nal deep well to the r1t. Simon-Hinkley aquifer.
Remedial Design is expected to occur in the Fall of 1987.
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A Record of Decision was siyned by'U.S. EPAon March 31, 1Y87 to provide
Carbon Treatment for two of St. Ar\thony's wells. - Remedial Design is ex-
pected to occur in fall of-1987. - .
On May 10, 1987 the U.S. Army proposed in a U.S. Army written "Record of
Decision" to implement a plume interception system known a's the "Boundary
Groundwater Recovery System" or BGRS. -The system has been constructed and
is ~eady for operation. On June 18, 1987 a'revised proposal on the BGRS was
submitted by the U.S. Army to the U.S. EPA and MPCA. This revised U.S. Army
proposal contained a responsiveness summary to pUblic comments received dur-
ing a twenty-one day public comment period (May 10, 1987 through June 1, 1987)
held by the Army. U.S. EPA has addressed the comments independently in Attach-
ment 2 to the ROD. .
.J
The recommended alternative in this ROD for Interim Remedial Action is to
operate the existing U.S. Army designed system, collect operational data, and
modify and refine the system as required to ensure adequate interception of
contaminated groundwater in both the Hillside Sand and Prairie du Chien/Jordan
aquifer. -
Enforcement
.
The Federal Facility Agreement (Ayreement) was announced on July 24, 19~7
and has been issued for public comment. The effective date of the Ayree-
ment will follow the consideration of public comments and incorporation
of comments. The Agreement is expected to become effective shortly after
the initiation, of the first- phase of- this remedial action.
~
The enforcement of the adequate operation of the system wi 11 be in accord-
ance with the terms of the Federal Facility Agreement on TCAAP and the
conditions in this ROD. The ~eneral conditions are;
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1.
Adequate capture of contaminated groundwater in both the
Prairie du Chien/Jordan and Hillside Sand Aquifer. Adequate
capture will be defined by capture of all contaminated, .
groundwater at the Southwest boundary that does not meet.
the criteria values in Table 1. The values in Table 1 are
based 0" drinking water standards and other health based
standards.
.1
2.
Adequate capture wi 11 be determi ned by a moni tori ng program
using the wells previously identified by the U.S. Army, MPCA
and U.S. EPA. -
3.
Treatment of extracted water will initially be by the existlng
air stripper. The air emissions .wi11 be monitored to ensure
that air emis)rons do not' exceed health based criteria. Addi-
tional study will be conducted within 90 days to establish if
health based effe-cts require additional controls. .-
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4.
MOdifications, if necessary, to achieve criteria values in
Taole 1 for capt~re of groundwater and discharge will ~e
implemented. '
Community Relations
The recent community relations activities are outlined in the beginning of
Attachment 2. In general the communi ty supports an effort to reduce vac
migration in the groundwater from the Southwest Boundary of the TCAAP. Many
of. the corrmments submitted during the U.S. Army's public comment periOd for
the proposed gradient control system relate to the adequacy of the prOPQsed
system and the-desire for approval or oversight by U.S. EPA and MPCA.
. The selected alternative utilizes existing equipment but provid~s for modifi-
cations of the existing equipn~nt to ensure protection of public'health and the
environment following a ninety (90) day trial period. A determination of final
performance levels will utilize data from the operation of the existing equipment
and an assessment of health risks associa~ed with the ground water not captured
,by the system.
.
The concerns regarding oversight are addressed by the TCAAP Federal Facility
Ayreement. The Agreement calls for review and oversight of the u.S. Army
Remedial Action by U.S. EPA and MPCA. Under the Agreement any mOdifications
. and performance of the system must be acceptable to U.S. EPA-and MPCA.
Alternati~s CORS+dered
The U.S. Army document Groundwater Remedial Action Alternative Analysis considers
various alternatives includlng the no actl0n alternative. Summary taoles of al-
ternatives are in Attachment 3.
The alternatives considered included:
1.
Source removal and no action on the migrating contaminated
water.
u
The sources of contamination have not been adequately charac-
terized and identification of all- the sources may not be
complete. Complete source removal can not be accompl ished
swiftly. Additionally~ it would not immediately mitigate
the contamination migrating off the base. Contaminates would
continue to migrate off TCAAP for years after the s6urce re-
'moval. Because no Remedi.al Investigati'on has been concluded
to adequately identifY all sources and the excessive time to
reduce_cont~inant miyrat!9~after source removal is complete,
this alternat~'e was not considered in detail by U.S. EPA.
2.
Mechanical barriers Source control and containment Slurry
walls, grout curtains and simil~r d~ices have been used
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extensively for control of contaminanj- plumes. They must be
used in conjunctio~ with pumping wells to prevent the contami-
nated groundwa~er from flowing around t~e barrier. Additional
reduction of the source of the contaminants to the groundwater
through capping or removal is also required. It would take one
to two years to install such a system. Given the depth and
extent of groundwater contamination, these mechanical barriers
are technically unacceptable. As a result, U.S EPA did not
consider this alternative in detail.
3.
Groundwater Extraction System - hydraulic barriers with or
without source removal and control.
The U.S. Army evaluated six varients of hydraulic barriers or
~radient control control systems in the document titled Ground-
water Remedial Action Alternative Analysis (GRAAA). All alter-
natives in the GRAAA considered pumping in both the Hillside
Sand. and Prairie du Chien/Jordan aquifers using data and the
detailed analysis found in the Groundwater Remedial Program Plan
(GRPP). The U.S. Army desiyned and constructed a system of
Gradient Control that encompasses six wells in only the Hillside
Sand aquifer. This system is now ready for operation.
.
Selected Remedy
The chosen alternative is to use the existing six wells at the boundary.
constru~ted bJL-the U.S. Army as part of their Boundary Groundwater Recovery
System to begin extracting contaminated groundwater and to begin design of
any additional measures required to accomplish complete capture of contamina-
ted groundwater. The U.S. Army estimates that the pumping of these six wells
will stop 90~ of the migrating VOC contaminantion. Information from the first
ninety (90) days of operation will be used by U.S. EPA to determine if the
existing six well system is adequate or needs to be modified to adequately
protect both the Hillside Sand Aquifer and the Prairie du Chien/Jordan Aquifer
from VOC contamination migrating from the TCAAP. . .
This remedy will ensure at least partial protection immediately and will allow
for a more rapid mOdification, if additional devices aje required, rather than
creating a new system. .
. The initial goal of the hydr~ulic gradient control system will not be restora-
tion of the aquifer to pristine conditionS'but rather the system is an operable
unit to mitigate impacts from further migratiqn.of VOC contaminants. The system,
with any necessary modifications, will provide for no release of contaminants
in excess of criteria levels from the southwest TCAAP bounqary. .
~ . .
The U.S. Army prep~red an ev~luation of various pumping schemes in the documer
Groundwater Remedial Action Alternatives Analysis, (GRAA) and Gro~ndwater Rem~ d1
~
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Action Plan (GRPP). The alternatives presented have been evaluated as. well
as the BG~S system proposed by the U.S. Army on June 18,1987. Operati'ng the'
BGRS in a modified manner from that. proposed on June 18,1987 by the U.S. Army
will not result in any adverse impacts. It is currently uncertain whether'
sufficient protection will be given to the Prairie du Chien/Jordan aquifer by
the BGRS as currently constructed. As a result the recommended alternative
is a two-phase approach.
The first phase will be to operate the existing six-pump out wells, treating
the water in the existing air strippers and utilize as much of the extracted
water as possible for in-plant use (approximately 300,000 gallons per day).
The remainder of the extracted. and treated water will be disposed of by re-
injection/infiltration through the arsenal sand and gravel pit (gravel pit).
The first phase will have as its goal to achieve capture of all groundwater
migrating from the southwest corner of TCAAP that has contamination in excess
of the criteria levels in Table 1.
The second phase starts after a ninety day trial period, evaluation of data,
and construction of modifications. Using actual operatin~ data and monitoring
results, the prot.ection yiven both aqui fers will be evaluated. Modifications
to the system, if necessary to achieve the criteria levels or ~rotect public
.
health, welfare, the environment, including additional additional wells or
carbon treatment, will then be installed. The criteria for capture or treatment
may be altered by U.S. EPA for Phase 2 based on a U.S. EPA study of Phase 1
data and results to be conducted prior to final implementation of Phase ~.
This alternative and the phased approach is recommended for the following.
reasons:
1.
Ar leastpartial protection of the Hillside Sand
achieved by pumping the existing wells and using
treatment'system. This degree of protection can
immediately during the first phase.
aquifer can be
the existing
be achieved
2.
The operation of the Phase. 2 system will prevent further additions
of contaminated groundwater to the regional groundwater system.
3.
Prevention of further migration of VOC contaminants in groundwater
from TCAAP is consistent with any forseen final remedial action
alternative.
MONITORING REQUIREMENTS OF SELECTED REMEDY.
The monitoring requirements of the initial phase i~ important in determininy
if the system js offering sufficient protection in both the Hillside Sand and
Prairie du Chien aquifers during the first phase and subsequent phases~
General Monitoring Re~~ements
0-
1.
Representative Sampliny.
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2.
All discharg~, eff~uent, and air emission samples. shall be taken at
a .point representative of the volu~e ~nd nature of each discharge.
A Monitoring/SaMpling Plan and Quality Assurance Project Plan
(QAPP) will be subMitted within thirty days after the initiation
of operation. The test procedures shall be detailed in the
QAPP and include calibration, maintenance,and testing proce-
dures and custody procedures.
3. 'Record Keeping
At a minimuM the following shall be performed:
. a)
All samples will be identified as to the exact place, time,
date and person perfonning the sampling.
b)
The date of analyses, person performing the analyses, techniques,
procedures and results' of analysis.
c)
All records sl1all be retained and made available to the U.S. EPA
upon request.
~onitoring Requirements - Groundwater
.
Initial Monitoring will be, conducted according to a monitoring plan that
was suhmitted in April lY87 and will be finalized within thirty (30) days
of initiation of operation to incorporate the a
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u.s. EPA has modifierl- this progra~ to consist of air emissions monitored
by an Organic Vapor Analyzer calibrated to trichloroethene (TCE) or simi lar '
Pquipment. The monitoring should occur at the TCAAP boundary and at the
, outlet of the air stripper stack. Air emissions should not reyister greater'
than 2 pp'" at the TCAAP bc;>undary and 20 ppn at the stack. Dai ly cal culations
of emissions based on air flOW influent concentrations and effluent concentra-
tions may be reported instead of OVA measure~nts at the stack. The frequency
of ~onitoring shall be daily f0r the first week, and weekly thereafter. If
either of these criteria val lies are exceeded, iMmediate notification will be
given to MPCA and U.S. EPA for a determination based on the health risk im~osea
if, operation of the plul"e interception system should continue.
Additional 'monitoring at,the nearest down wind resident using a ~ublic water
systeM should be performed. The time, date, direction of the wind, approximate
wind speed and location of sample will be noted. An air sam~le will be'taken
npar the dwelling and analyzed for VOf. contaminants. This residential moni-'
toring should occur six times during the first ninety (90} days of op~ration
and monthly thereafter. All measurements will be taken while the system is
operating. The residential I'1Onitoring program will be developed in cooperdtion
with U.S. EPA anrl MPCA.
SYSTn1 PERFORr1Ar-£E RF.OUIREf-1ENTS ('f SELECTED REMEDY
.
Operation - Criteria Level
During Phase 1, operation of the existing system may not fully protect health
and'the environment. However, sone degree of protection will be achieved by
reducing the amount of VOC contamination nigrating off-TCAAP in the groundwater.
This reduction is an inmediately achievable and desirable product of operation.
The constraints on this operation are to ensure that no endangerment to public
health and the environl"ent occurs due to the opertion of the existing system.
Thus, the constraints apply to the protection of the receptors of discharyes
and efT1i ss ions of the sys~ em. '
Because the treated water is to be used for dr,i nk i ng water and process water at
the plant all the linits at the plant should meet state and federal standards
for drinking water. U.S. EPA has decided that the cumulative risk for car-
cinogens (cancer causing substances) of 1U-o ( one in a million incremental
cancer risk) is a desirahle goal. , The State of Minnesota has a standard based
on 10-5 risk levels (Recommended Allowable levels) for private water supplies.
The risk associated with the in-plant use' of treated water should not exceed
10-6 incremental c'ancer risk. . The carcinogenic criteria of a cunulative' car-
cinogenic risk of 1 X 10-6 was choosen based on an asseSSMent of risks. The
. criteria falls within the acceptable range of 10-4 to 10-7. The U.S. EPA
"Gui dance Document fo'r provi di ng A lternat i ve Water Supp 1 i es II (August l~!:! 7)
suggests 10-6 risk level as a cCJl1mon.target. Similarly the.U.S. EPA "Alter-
nate Concentration Limit Guidance" (Uswer Directive 94981.UO-6C, July 1~87)
defines a level of ~-6' a9 "a point of departure" and requires justification
for using a c1ifferent revel of risk for exposure levels at receptors.. It is
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expected that the additional treatment through the existiny carbon filtration
system used for in-plant production water supply will ensure that water used.
on TCAAP will meet a cumulative risk-based criteria of 10-6 for.carcino~ens.
Water from the air stripper will also be discharged to the gravel pit. Water
discharged at the gravel pit must at least meet the contaminant specific re-
quirements-colum of Table 1. The discharged wat~r leaving the boundary should
have contaminant levels that add to an excess cancer risk below 1 x 1U-b at tne
nearest receptor. The deronstration of the achievement of this level at protec-
tion shall be the current risk levels used to calculatp. the total risk froM
carcinogens as given in Table 1. Th~ risk levels currently used by U.S. EPA
shown on Table 1 are subject to modification based on new information on health
impacts.
The non-carcinogenic substances at the receptors shall not exceea the values
in. the Acceptahle Risk Colurm of Table 1. A summary of criteria levels to b.e
applied to the phases of operation is given in Table 3.
System Capture
The ~ppcific ohjective of the system is to prevent migration of VUC contami.nated
grounrlwater in both the Hillside Sand Aquifer and the Prairie du Chien/ Jorda~
Aquifer at the Southwest boundary of TCAAP. The system, after com~letion of
Phase 2 , shall prevent mi grat i on of all contami nated groundwater in the two
aquifers which has concentr~tion 'of contaminants that exceeds the criteria
levels. Additional modifications may be required to achieve the criteria
levels. The criteria levels may be changed for the second phase based on an
assessment of health impacts by U.S. EPA. .
-::..
System Treatment
All water discharged after treatment will meet the contaminant s~ecific
requiremPnts in Table 1 during Phase 1. During Phase 2, standards may be
required based on actual operation data and health risk data. Additionally
at no time will a receptor of discharged water be exposed to a cUMulative risk'
due to the di scharged water greater than that of 1 x lU-6 for ca rci'noyens or
concentrations in excess of the chronic acceptable intake concentrations for
non-carcinogens.
Air Emissions
-The concentration of TCE in the air emissions is expected to be 76 uy/liter
of air measured at the air stripper exit. This emission compares favorably
to the 1hreshold Limit Value - Time Weighted Average (TWA) of 27U uy/lit~r
(270 mg/m3). The nJA is published by the American Conference of Governnent
Industrial Hygienis~ af'ld .is a value expected not to have adverse affects
on nearly all workers~txposed to that concentration over a normal work week.
A study t\y the lI.S. EPA of the data collected during the ninety (90r'day trial
.
-------
'.
-9-
periorl in Phase 1 wfl 1. be conducted, to assess the need for addi tional controls
to anequately protect hu~n health and the environnent from long term (chronic)
exposure .fran VOC emissions. No short term or aCllte health effects are antfci-
pated from the air erniSS10nS -of the air stripper. The expected concentrations
of the emitteci Tr.E (the major carinogen contaminant by volune) are 'expected to
be well below 10-6 risk levels at the bo~ndary of TCAAP. Monitoriny to assure
that no impacts on puhlic health occur is incorpor~ted as part of tllis ROU.
System Effectiveness
The initial. gO days of operation (Phase 1) will be used to conect data on
groundwater captu~e in hoth aquifers. If groundwater capture does not ~et the
requirements or the treat~ent system requires modification, a plan to mOdifj the
systen to neet the objectives will be submitted to the U.S. EPA and MPCA within
sixty (60) days of conclusion of Phase I (l5U nays from initial operation date).
Within 150 days of acceptance by U.S. EPA, construction and operation of the
modifications will begin.
Facilities Operation andOuality Control
.
Within sixty (60) days of Phase. I start-up Qf the system a detailed o\Jeration
plan shall be slJhmitted tn the U.S. EPA and the system shall be operated 'in a .
manner consistent with the following:
a)
~aintenance of' the treatment facility that will result in
degradation of effluent quality shall be scheduled as nuch as
~ossi~ during non-critical water qua1ity periods and shall
be performed in acco,rdancewith a work plan subject to Part
XIV of the Agreement, that has passed the Consistency Test.
b)
The Operator shall provide an adequate operating staff
which is duly qualffied to carry out the operation, main-
tenance and testing functions required to insure co~pliance
with the performance requirements of the system.
c)
. .
The system shall at all times be Maintained in good working
order. The system shall operate as efficiently as possible,
all facilities or systems of control installed or used to
aChieve the necessary levels of' control.
d)
Necessary in-plant control teste; shall be conducted at a
frequency adequate to ensure continuous efficient operation
of the treatment facility. .
e)
Solirls, or other pollutants removed frCJr1 or res'ulting froo
treatment ~r c~ntrol of wastewaters shall be disposed of in
"". .
SuCh manner as to prevent any pollutant from suCh materials
from entering surface.waters. The disposal of such materials
shall c~ply with all 'applicahle Statutes and Regulations.
.
-------
-10-
f) ,
Adequate safeguards to prevent the dischargp. of untreated or
in~rtequately treated groundwater shall be ~aintained at all
times. System reliability shall be maintained by means of al-
ternate power sources, back-up systeMS, storaye of inadequately
treated effluent, or other appro~riate methods. .
Notificat~on of upsets or emergency situations
If for any reason the systeM does not meet a discharge requirement or a
capture criteria, an emergency situation develops, by-pass is re~uired or the
systeM does not operate as planned notification of the U.S. EPA and M~A will
occur iM~diately. .
:'
The notification shall include:,
1.
A description of the incirtent, the a~ount of discharge and
cause.
2.
The period of the incident including dates and ti~e, and
anticipated time to correction and steps taken or planned.
.
Gravel Pit Water Balance
Within thirty '(30) days, a water balance study "to' conf""" that soil ~eme-
ability at the gravel pit will accommodate the discharge fro~ the Hillside
Sand and Prairie du Chien Aquifers gradient control system will be perfonned.'
In order t9 accom~odate rapid imple~ntation, this may be submitted in phases,
the firs~water-talance report shall reflect the existing six well gradip.nt
control system using esti~tes. A second water balance shall be submitted
at the time of submittal of a proposal for any modifications for Phase 2 using
past data.
An annual water balance study shall be submitted incor~orating all ~ite neteoro-
logical and anthropogenic sources or sinks of water to the infiltration basin.
Monthly precipitation, t~perature, change in infiltration basin water lev~ls,
potential evaporation, effluent discharge and run off received will be incorp-
orat~ in the water balance study and recharge to the aquifer will be estimated.
S'c h ed u 1 e
This sUMfT1ary of operation' is as follows:
1.
Operate the system for a ninety (9U) day trial period and collect
data on grounqwa ter capture, .a i r emi ss ions, a nd the treated water.
..~. .
Within 150 days of initiation of Phase I (60 days after Ph4se I trial
period) suhmit a plan, to U.S. F.:PA and HPCA. which either; a) der.1onstrates
that the systS'1 ~ets the requirement for operation or; b,)"pro~oses .
modifications to the system to ach~eve the requirement_~Q.d",:,-criteria
2.
-------
-11-
in Table 1. The plan shall contain a schedule for implementation of
the modification.
3.
Within 150 days -of the U.S. EPA issuance -of notice of an acceptable plan
for modifications in Phase 2, the modifications shall be constructed and
begin operation.
Studies, Reports and Plans
A schedule of documents to establish the operation characteristics of the
system is as follows:
1.
Initial operation
Phase 1
Monitoring/Sampling Plan
3U days after initiation
OAPP
3U days after initiation
Operation and Haintenancp Procedure Plan
60 days after initiation
Monitoring reports
periodically as per Ta~e 2
2.
DeMonstration of a~equacy of proposal for
modification including:
150 days after start -
up of i nit i at ion
Work plan for modification
Monitoring Plan .rrodification
S amJll i ng .,Q4.a n
OAPP
Schedu 1 e
3.
Operation of mOdification - Phase 2
15U days after U.S. EPA
issuance of an acceptable
plan
..~.
0-
/'
.
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-12-
APPLICABLE OR RELEVANT AND APP~OPRIATE REQUIREMENTS, AND OTHER
STANDARDS TO BE CONSIDERED
Two key components of the hydraulic gradient control system require consi-
deration of media-specific environmental laws, regulations and standards.
The components are: (1) ca~ture criteria for contaminated groundwater, and
(2) water discharges and air emissions. Contaminated grou~dwater will De
captured by the extraction wells for treatment, air emissions will occur into
the ambient atmosphere from the air stripper unit and treated water will be
discharged from the treatment system into either the infiltration basin or
the TCAAP potable and in-plant process water supplies. These activities must
be conducted in a manner which complies with all applicable or relevant and.
appro~riate requirements as required by Section 121 of CERCLA, as amended,
42 U.S.C. ~9621. --
The two medium-specific laws applicable or.relevant and appropriate .to operation
of the hydraulic gradient control system are the Clean Air Act, 42 U.S.C. ~7401,
et ~, and the Safe Drinking Water Act, 42 U.S.C. ~300f, ~~. In addition,
the gradient control system shall be operated s06as not to creat~ an incremental
cancer risk for carcjnogens in excess of 1 x 10- for human receptors. A summary
of capture criteria and dischar~e and emission limitations to be applied to the
gradient control system which were drawn from the Clean Water Act, the Saf~ .
Drinking Water Act and incremental ca~cer risk calculations are lis~ed in Table 3.
AIR
The air stripper shall remove at least 98% of the VOC contamination from the
extracted yroundwater. To achi eve thi s effi ci.ency the .system must di sCharge
VOCs into~he amb-ient air at TCMP. However, the air stripper must be opera-
ted in a manner which causes no unacceptable health risks and which causes no
unacceptable degradation of ambient air quality. The system must also be
operated in a manner meeting the emission limitations set forth in the System
Performance re4uirements section of this Record of Decision.
The Minneapolis/St. Paul area is treated as an "attainment" area with respect
to ozone National Ambient Air Quality Standards ("NAAQS"), 4U CFR Partcn.324,
and identical State Ambient Air Quality Standards ("SAAQS") found at Minn. Rules
70US.0080. However, emissions of VOCs from TCAAP must be consistent with the.
State Implementation Plan designed for maintenance of NAAQS and SAAQS, and with
requirements established by the State for. new emission sources, !.,inn. Rules
7UU5.U115..
Pursuant to federal regulations, the TCAAP facility is currently considered a
minor VOC source. A minor source generates less than 100 tons/year of VOC emis-
sion. 42 U.S.C. ~7602(j).. The gradient control system at TCAAP constitutes a
modification to a minor emission source. Pursuant to Prevention of Significant
Deterioration ("PSD") regulations, 40 CFR Part 52, a newly constructed source
or a modificat~on toe-,.i1inor source may emit up to 2~0 tons/year of VOCs without
being subject to PSD regulations. vac emissions from the air stripper are esti-
mated to be .approximately 5 ton~/year (26 lb?/day in groundwater x 36.5 days = 94
-------
--1 3-
TCAAP facility will emit VOCs in excess of the 250 tons/year threshold
established by U.S. EPA for PSD.
State law is applicable to the air stripper component of the system. State
rules provide that an emission facility with potential (worse case) emission
in excess of 2~ tons/year of criteria pollutant (e.g. VOC) must seek and ob-
tain a State air emission facility permit. Minn. Rules 70U1.121U. The State
has'determined that the TCAAP facility, including the air stripper, will have
potential emission capacity of VOC in excess of 25 tons/year.
Pursuant to State requirements found at Minn. Rules 7001.1212, and consistent
with Section 121(e) of CE~CLA, 42 U.S.C. ~9621(e), the Army shall submit a
Notice to the State of intention ~o operate the air stripper. This noti~e
shall provide the State with all information necessary to evaluate the emission
source. The information shall include an estimate of VOC emissions from the
air stripper under' maximum load/worst case conditions as well as an estimate
of VOC emissions from the TCAAP facility (including all sources) under maximum
load/worst case conditions. This Notice to the State shall stand in lieu of
an application for a State air emission facility permit for the air stripper.
In the abs~nce of Section 12l(e)(1) of CERCLA, 42 U.S.C. ~9621(e)(1), upon
review of the Notice and/or data compiled from Phase I operation of the air
stripper, the State could issue permit conditions for operation of the air
stripper. However, because any such conditions constitute non-promulgated
State requirement~, any conditions recoml~nded by the State for operation
of the air stripper shall be forwarded to U.S. EPA -for review. The State1s
recommendations will be implemented as necessary to ensure adequate protection
of human h~a1 th Ed the envi ronment. .
Additjonal operating requirements and controls may be requested at any time
by U.S. EPA as determined necessary duriny the useful life of the system.
Additional operatiny requirements may necessitate modification of the system
to adequately protect human health and the environment based upon risk calcu-
lations using Phase I data from actual operation of the system.
.
. .
Section 112 of the Clean Air Act, 42 U.S.C. ~7412, identifies certajn poilutants
for which no NAAQS apply, but which cause or contribute to air pollution and
which may reasonably be anticipated to result in an increase in mortality,
serious irreversible or incapacitating reversible illness. U.S. EPA has esta-
blished National Emission Standards for Hazardous Air Pollutants ("NESHAPs")
to regulate emissions of certain such polrutants.
NESHAPs- are source specific (i;e. industrial catagories) regulations promulgated
for certain hazardous pollutants includlng: arsenic, asbestos, benzene, beryllium,
mercury, radionuclides and, vinyl chloride. Of these pollutants, benz.ene, radion-
uclides (primari1.Y radon) and vinyl chloride may be of concern .at TCAAP.
NESHAP standards appl~l'o 5pecifi c i ndustri a 1 sourees..whi eh dO not i ne 1 ude the
air stripper unit of TCAAP. However, since hazardous air pollutants will be
emi tted from the syst em, NESHAP, standards are cons i dered relevant ancf appropri ate
to operation of the air stripper. The.relevant and appropriate NESHAP standards
are as' follows:
.
-------
-14- .
Pollutant
emission standard
benzene -'
no detectable emission
(500 ppm detection limit)
radon 222
proper desiyn and operation
of source
(applies to mining operations)
vinyl chloride
lOp pm
In addition to the named NESHAP pollutants, U.S. EPA has identified additional
suspected hazardous pollutants of concern. A partial list of these pollutants
is found at 40 CF~ Part 61.02(b). Emissions of named NESHAP pollutants and
of suspected hazardous pollutants from the air stripper will be regulated as
necessary to protec5 human health and the environment. A level of protection
of at least 1 x 10- incremental cancer risk for carcinogens. considering
cumulative effects, will be achieved during operation of the system.
Water Discharge
The gradi ent control system wi 11 extract groundwater, treat the groundwater,
and discharye the treated yroundwater to either the aquifer system' via. an
on-site infiltration basin or to the TCAAP in-plant potable and process
water supplies. Both receptors of treated groundwater, the aquifer and the
in-plant water system, provide a potential source of drinking water. Therefore,
the discharge of treated water must meet or exceed water quality standards'
estab1isheo foriCrinking water supplies.
.
Discharge limitations for operation of the system have been set forth in
the Contaminant Specific Requirements column of Tao1e 1. These discharge
limitations have been derived from Maximum Contaminant Levels (HMCLs") and
non-zero Maximum Contaminant Level Goals (HMCLGsH) of the Safe Drinking
Water Act (IISDWAH), recommended allowable limits (HRALsH) proposed by the
State, and U.S. EPA Health Effects Advisories. .
The SDWA establishes Maximum Contaminant Levels (HMCLs") for drinking water
supplied from an underground source of drinking water through a public water.
supply. MCLs are relevant and appropriat~ standards to apply to discharges
from the system because such di scharges ma,y combi ne wi thdri nk i ng water sup-
plies. For those contaminants for which MCLs have not been developed, SDWA
non-zero MCLGs, RA~s, and U.S. ~PA Health Effects Advisories have been utilized
as relevant and appropriate"requirements to establish discharge limitations.
The discharge limitations set forth in the Contaminant Specific Requirements
in Table 1 aresuffi.ient to ensure adequate protection of human health and
the environment from it~te adverse health effects from discharges from the
system to a potential' source of drinking water. The discharges. of treated
water will be sampl ed as set forth in Table 2 to en'sure compl ianc,e w;-th the
limits set forth in the Contaminant Specific ~equirell1ents of Table 1.
, .
\
\
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-15-
In addition to the Contaminant Specific Requirements, no human receptor of
drinking water affected by- the system (downgradient users of drinking water
and users of TCAAP in-plant drinkiny water) shall be ex~osed to concentrations
of any contaminant which exceeds levels established as Acceptable. Risk Levels
in Table 1. The receptor-based Acceptable Risk Levels have been established
for single carcinogens by determining the maximum allowable concentration for
each carcinoyen in drinking water which may be ingested in a human rgcePtor's
lifetime which will not exceed an incremental cancer risk of 1 x 10- for the
human receptor. In addition, no human recep~or shall be subject to cumulative
incremental cancer risk in excess of 1 x 10- from multiple carcinogens.
Therefore, no receptor shall be exposed to drinking water affected by this
system which contains multiple carcinogens at concentrations Whigh create a
cumulative lifetime incremental cancer risk in excess of 1 x 10- .
The receptor-based Acceptable Risk Limits have been established for non-
carcinogen contaminants based on Federal Water Quality Criteria of the Clean
Water Act, adjusted for ingestion of drinking water only, and Acceptable Intake
Concentrations for chronic health effects. These Acceptable Risk Levels are
1 i sted in the Su perfund Hea 1 thE va lua t ion Manua 1. (EPA/540/l-86/U6U .
October, 19~6).
e
CAPTURE CR ITER IA
In addition to the discharges and emissions from the system, capture criteria
are established to determine whith groundwaters located at TCAAP must be treated
by the system. The Hillside Sand and the Prairie du Chien/Jordan aquifers are
primary drinkiny water supplie~. Therefore, VOC capture criteria have also been
establish~ using SDWA MCLs and nonzero MCLGs, RALs, and U.S. EPA Health Effects
. Advisories. The-VaC capture criteria are set forth in the Contaminant Specific
Requirements for'VaCs listed in Table 1.
. The gradient control system shall be operated until all ~roundwater flowing
into the capture system, or migrating from the southwest boundary of TCAAP,
meets or exceeds the established capture criteria.
Reduction of Toxicity, MObility or Volume
All alternative pump-out schemes evaluated would result in simi.lar reductions
of toxicity, mobility or vo)ume. All systems evalutated rely on an air stripper
or carbon filtratiDn or both. The contaminants of. concern are vacs migrating
in the groundwater from the southwest boundary of the TCAAP. The des i g'n of the
system using the existing equipment is to intercept 90% of the vac contaminant
loading in the groundwater. freated extraction water wil} be used in-plant.
including potable water supply ,and the remainder discharged to the"arsenal
gravel pit for eventual recharge. Approximately 98% of the VOC contaminants
captured will be emitted as air emissions.
~~.
Effectiveness of Remedy
The chosen remedy will not immediately reduce the short-term risks to users of
.
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-16-
the drinking water aquifer. The velocity of the grou~dwater is relatively slow
ann the plume affecting current users, including the Cities of New Brighton and
St. Anthony, wi 11 not be affected in the very short-term. However, the alnou.nt
of VOC contaMinants leaving th~ southwest boundary of TCAAP will be reduced
immediately. If the system 'requires modification, the plan for roodification
will be developed within 150 days of initiation of operation. Operation of
the modifications would be scheduled within 150 days of the submittiny of an
acceptable plan.
The pumping system requires continous operation and maintenance as well as
detailed monitoring of both the ground water and the discharges. It is
expected to cost approximately $8,1UOO per month for groundwater monitoriny,
operation and routine r"aintenance in the current confiyuration. As stated
previously, the discharge will meet all drinking water standards during all
phases of operation. The VOC contaminant concentration in the groundwater
migrating from.the southwest TCAAP boundary (groundwater not capturen) wi 11
at least meet drinking water standards at the c~nc1usion of the final ~hase
(approximately 13 months frOO1 initiation). Table 1 lists the pertinent VOC
contaminants, the standards and associaten carcinogen risks. The carcinogenic
risk associated with the contaminant specific requirements total 4.~ x 1U-4
under an assumption of additivity of risks. Tables 1, 2 and 3 in conjunction
with the BClRS I'1Onitoring plan identifies all parameters monitored and the de-
tection limits associated with the monitoring program for hazardous substanc~s.
Imp1ementabi1ity and Feasibility of Selected Remedy
This alternative w~s chosen hecallse hydraulic gradient control systems such as
the selected choice a're a well known technology with a proven record of relia-
bility. ~Whi1~t is expected by U.S. EPA that full control of the miyrating
VOCs ~ill require further expansion of the system~ the operation of the existing
equipment (the six wells, air stripper and related equipment) can ~rovide some
some control of the contamination immediately.
C os-t s
The capital cost of planning, construction and other costs for the system
currently existing is approximately 4 Million dollars. "1onitoriny and oper-
ating costs equal eight (8) to ten (10) thousand dollars per month (u~ to
$120 thousand per year).
Further capital expenditures may occur within one year should addition~l
extraction wells he required and significant capital costs will be incurred
if treatment of the air emis~ions of the air stripper or re~lac~ent of the
air stripper with other technologies is required to achieve adequate treatment
. of extracted water. .
Significant efforts in review and analysis of the results of the initial ninety
(90) days will be required by U.S. EPA and other revi~wers of the material.
Perfornance of anat~s of the system operation and proposed modifications wil'
require intensive efforts to assure timely modifications. '.- .
..
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-17 -
Community Acce~tance
The COMmunity has expresse~ ~ strong support for a system such as the 'selected
remedy. During the public comment period held by the U.S. Army reservations
, were expressed about the completeness of the system as it is currently desiyned.
Thp system in its current confiyuration has a short trial period (~U days) and
is scheduled to be fully modified in approximately one year.
. Reservations also were expressed during the puhlic corn~ent ~eriod about the
proposed use of the discharged treated water. The U.S. EPA feels that discharge
to the Grav~l pit and in-plant use are acceptable end uses for treated water.
State Acceptance
The State of r~innesota through the t~PCA concurs with the concepts of a phased
approach of a hydraulic ,gradip.nt control systen such as the selp.cted rer!1edy.
The MPCA listed watp.r quality standards for discharge at the air stri~per
are based on a .10-5 increrrental cancer risk for carcinogens. The U.S. EPA
requir~ents are based on a 10-6 incremental cancer risk for carcinogens at
the receptor. To some np.grpe. the state requirenents are possibly stricter'
at the receptor nue to dilution in the groundwater ~nd the U.S. EPA standards.
are stricter for the in-plant users. Overall impacts are equivalent for either
- set of standards.
Overall Prot~ction of Human Health and the Environment
The sele~ted ~tem will be operated so as to provide ~rotection of users of the
extracted water discharged in the groundwater and in-plant. The users of yround-
water will not immediately have clean groundwater due to the slow travel time of
groundwater. It is expected that if the systeM were 1uUl, effective in haltiny
the l'1i grat i on of Vex: cant al'Ti nants it wou1'd .t-ake 25-4U years for the remedi at ion
to be cOfTlpl ete.
During all phases of the rel'1edy the protection of receptors will be based on
health criteria, while discharged water will at least meet drinking water
standards. The cUl'1ulative carcinogen risk-based criteria for receptors of
1 X 10-6 is based on the generally accepted practice for ex~osure asseSSlT1ents
and ~lternat1Yes r~dy development. (See for exanple Superfund Public Health
Evaluation Manual-EPA 540/1-86/060 1986 and Guidance on Feasibility Studies
under CERCLA April 1985. '
c.~.
.
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TAULE 1
APPLICABLE OR RELEVANT ANO APPROPRIATE REQUIREMENTS
II
Contaminant Acceptable
SpecifiF Risk Lgvel(b) Expected level
Requirements(a) 10- in discharge
Substance !' ~ ~ ~
.
.
VOLATILE ORGANIC COMPOUNDS (VOC)
BENZENE 5 ( HC L) 0.67 NO
. TOULUENE. 2000 (MCLGP) . NO
CIS 1.2-DICHLOROETHENE plus 70 (HCLGP) <1
TRANS 1.2-0ICHlOROETHENE <1
1.1-DICHlOROETHENE 7 (MCL) 0.033 <1
l.l.l-TRICHLOROETHANE 200 (HCL) 22 <1
1.1. Z- TR ICHLOROE THANE 6.1 (RAl) U.6 <1
1.2-UICHLOROETHANE ~ (MCL) U.3H
1.1.2~HICHLOROETHENE ~ (MC l) 2.H <5
1.2-UICHLOROPROPANE 6 (MCLGP) U.~6
1.l.2.2-TETRACHlOROETHANE 6.9 ~RAL~ U. 7
CARBON TETRACHlORIUE ~ MCl U.3
1.1.2-TRICHLOROTRIFLOUROETHANE - ( GA )
CHLOROFORM 5 ~ R AL ~ 0.1~ <1
VINYL CHLORIDE 2 I~Cl U.015 <2
XYLENE 440 (MCUiP) NU .
'1.1-DICHlOROETHANE - ( GA )
r~E TAL S
ARSENIC 50 (MCl ~ 0.25 NA.
BAR I LM 1000 (HCL 100U (HCL) NA
CYANWE .2UO (HCl) 200 (WQC) NA
CADMIUM 5 (HCLP) 10 ( WQC ) NA
LEAD 20 (MCLGP) O. Oil NA
NICKEL 15U (HA) 1 5.4 (WQC) NA
MERCURY 2 (MCL) 2 . 0 ( MC L ) NA
-------
TABLE 1 - CONTINUATION
Substance
Contaminant
specific
requ i remen~ls ( a)
~
50 (MCl) I
5000 (MCl)
Acceptab 1 e
Jhsk Level(b)
10-b
~
50 (MCl)
500 (WQC)
E xpec ted 1 eve 1
in discharye
~)
CHtWt4IUM
ZINC
, NA
NA
~
II
POlYCHlOKINATEf}.BIPHENYl
TOTAL
0.008
NA
RADIONUClIOES
total ALPHA EMITTING
total HETA EMITTING
tota 1 GAHl4A EMITTING
RAUON.
15 pc 1/1 ( MC L )
~o pc 1/1 (MCl)
50 pc i 11 .
AI~ EMISSIO~S
~AUON (At stack)
VUC (total at stack)
VOC (total at boundary)
BENZENE
VINYL CHlOtHOE
20ppm (ATSD~)
2ppm (ATSD~)
500ppm (CAA ~ 112)
1 Up pm (CAA ~ 11 2 )
.,
-------
..
**Notes for Table 1**
(a) Applicable to all phases, capture and discharge
(b) Receptor based criteria for Phase 2. Laboratory detection limits may be
substi&uted for criteria levels with U.S. EPA approval. Values are based
on 10- risk level for carcinogens and for non-carinogens the stricter
limit determined by MCL, AlC or Water Quality criteria adjusted for inges-'
tion of drinking water oniy. .
* MCL Maximum Contaminant Level
* MCL Maximum Contaminant Level Proposed
* MCLG Maximum Contaminant Level Goal
* MCLGP Maximum Contaminant Level Proposed
* HA Lifetime Health Advisory
* RAL Recommended All owab 1 e Leve 1 - State of r~i nnesota
* SMCL .Secondary Maximum Contaminant Level
* NU None detectable
* NA Not significantly affected by remedy - not expected to be migrating fr~m
sources and wi 11 relna in at backyround 1 eve 1 s
* CAA Clean Air Act
* AlC Chronic Acceptable Intake
* WQC Water Quality Criteria - adgpted for ingestion
concentrations represent 1 x 10- riSk levels
.
of drinking water only -
*GA
Group Action Criteria of 10 ppbadopted
* ATSDR Agency for Toxic Substances and Disease Registry recommended action
1 evel for BGRS.
-=-
..~.
/'
.
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Table 2
- EFFLUENT MONITORING REQUIREMENTS
Characteristic
Flow-m3/day (MGD) (influent, effuent)
Measurement Frequency
continous
Influent
Influent
E ffl uent
Effluent
total VOC (2)
trichloroethene
total VOC (2)
trichloroethene
quarterly (1)
quarterly (1)
quarterly (1)
qua rt e r 1 y (1)
Phosphorus-total
Phosphorus-ortno
monthly
monthly
Lead-tota'l
Zinc total
Chromium total
Cop~er total
Nickel total
Cyanide
Mercury
Trichloroethene
PH"
quarterly
quarterly
quarterly
quarterly
quarterly
quarterly
quarterly
qua rt e r 1 y (1)
quarterly (1)
.
Arochlor 1-248
Arochlor 126U
Arochlor 1254
Arochlor 1242
~rochl..Q£. 1016
annual (3)
annual (3)
annual (3)
annual (3)
annual (3)
Radionuclide group
. gross alpha scans
gross beta scans
gross gamma scans
radon 222
( 4 ) .
quarterly
quarterly
quarterly
quarterly/weekly
Substances on Table 1
monthly (5) .
(1) Sampl es shall be be weekly for fi rst 9U days followi ng' start-up
monthly for the remainder throuyh the first 12 months' of operation
and quarterly thereafter. More ..frequent monitoring maybe required
on the first 90 days of operation of any modifications of system.
(2) Total VOC includes a1'l .parameters on Table 1.
(3) Total.sam~liny frequency shall be monthly for first year an
. quarterly r,hereafter.
(4) If substanc\~4Qve'r criteria 'table 3 then identify scource compound.
.-
/
(5) Samples shall be taken. at least four times during 90 day trail
period (days, 30, 6U, 9U) and monthly thereafter. Air emission
monitoring requirements is given in.text.
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TABLE 3
SUMMARY OF CRITERIA LEVELS
Period of Operation
Criteria for Substances
migrating from TCAAP
Phase I (day 0 - 345)
discharge criteria = contaminant
specffic
- initial operation (day U -~U)
capture criteria = none
receptor criteria = 1 X 10-6 or AIC
data evaluation and modifications
propos.al (day 9U-15U)
- U.S. EPA/MPCA review of modification
(day 15U-345)
- Construction of modification
(day 19b-34)
Phase 2
.
- operation of modified system (after day 345) discharge criteria = contamin~-.
spec ifi c -
capture c~iteria = contaminagt specif-
receptor criteria = 1 x 10 - or AIC
later P~ases-1Dot anticipated-required if phase 2 criteria not achieved).
- operation of further modifications if
required to achieve or maintain criteria
levels for phase 2
*** Notes
* discharge criteria applies to discharge of the air stripper and refers
to contaminant specific levels (eg MCL) of table 1.
* capture cr1 teri a appl i es to groundwa.ter mi grat i ng of f- TCAAP in both the
Prairie du Chien/Jordan and Hillside"Sand aquifers at the south~est.
boundary of TCAAP.
* receptor criteria applies 10 only the treated water leaving the carbon
treatment system for ON-TCAAP use and to only the treated groundwater at
"the nearest receptor (generally at the boundary). .
* AIC ref.ers to ~~ic' acceQt!!?le intake concentration for drinking,water
only. .
. .
* 1 x 10-6 ref.eg to total cumultative risk of all carcinogens estimated
to be 1 x 10- or less
. - .
* contaminant specific refers to contaminant specific requir~nents
(e~ MCl, RAl, o~ AIC)
" "
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~
..~.
ATTAr.HMJ::NT 2
.QFSPn.NS IVF.NF<;S SIIM'~AQY
..
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.
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TWIN CITIES ARMY AMMUNITION PLANT (TCAAP), NEW BRIGHTON, MINNESOT~,
BOUNDARY GROUND-WATER RECOVERY SYSTEM
RESPON.S I VENESS SUMMARY
This community rela~ions responsiveness summary is divided into the
following sections:
Section I
Overview. This section discusses the U.S. Environmental
Protec~ion Agency's (U.S. EPA) preferred alternative for interim
action, and likely public reaction to this alternative.
Section II
Background on Community Involvement and Concerns. This sec~ion
provides a brief history of community interest and concerns at
'the TCAAP site.
Sec~ion III
Summary of Major Comments Received durin& the Public Comment
Period and the U.S. EPA responses to the Comments. Both written
and oral comments are categorized by relevant topics. U.S. EPA
responses to these major comments are also provided.
Section IV
Remaining Public Concerns. This section describes remaining
community concerns th~t U.S. EPA, HPCA, and U.S. Army should be
aware of in conduc~ing the interim action at the TCAAP site.
.
I.
OVERVIEW
As no~ee previously in this ROD, the TCAAP site is unique in that it is
the first ROD signed for a Department of Defense federal facility since the
passage of the Superfund Amendmen~s and Reauthorization Act of 1986 (SARA) and
the first action to be implemented under an inter-agency agreement between the
Departmen~ of Defense and U.S. EPA. A~ the time of ~he public comment period,
an agreement had not been reachea between U.S. EPA, HPCA, and the C.S. Army
regarding each organiza~ion's roles, responsibilities, and authority at the
si~e. An agreement was announced between these ~hree organizations on July
24, 1987, and is refered to in this responsiveness summary as the "Agreement."
In Hay 1987, the U.S. Army held a public comment period on this proposed
in~erim ac~ion, which was referred ~o at that time as a proposed ROD. This'
. proposed inierim action consist~d of a boundary ground-water recovery syste~
-- a series of six wells that would draw ,contaminated ground water migrating
off the southwes~ boundary of ~he TCAA~ facility; t.reat ,the ground wa~er with
air s~ripping; and use a portion of the treated:water for in-plant use after
carbon filt.ration; The r~maining por~ion was to be discharged to t.he aquifer'
~hrough a gravel pit on the TCAAP facility. The comments responded ,to in
Section III of this responsiveness summary were init.ially addressed to t.he
U.S. Army on its propa.s...~ interim action, not to U.S..EPA. '
U.S. EPA's final alterna~ive for interim action concurs with' the ~.S.
Army's choice of, a ground-wa~er recovery system, with modificCitions ~o 'the
capture criteria and deadlines for mee~ing these
.
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-2-
criteria. 'The modifications were, in part, based upon comments received
during the public comment period. Additionally, U.S. EPA's final alternative
for interim action allows for effluent discharge ~o points other than th~
aquifer. This was initially evaluated and proposed by the U.S. Army, who
later withdrew it from their preferred interim action.
Judging from the comments received during the comment period, the public
would strongly support U.S. EPA's final alternative for interim action as a
first step in addressing contamination associated with the site. As detailed
in Section IV of this responsiveness summary, however, the public has numerous
remaining concerns regarding the site. This action by U.S. EPA supplements
the decision proposed by the U.S. Army and pres~nted to the public.
II.
BACKGROUND ON COMMUNITY INVOLVEMENT AND CONCERNS
Contaminated ground water has been an issue of very high concern in the
community sin~e it ~as initially discovered by MPCA in 1981. In the six years
since the initial discovery, a number of residential and municipal wells have
been abandoned because of high levels of Volatile Organic Compounds (VOCs).
under the provisions of the Comprehensive Environmental Response
Compensation and Liability Act of 1980 (CERCLA), U.S. EPA and ~PCA have taken.
a number of actions in the New Brighton/Arden Hills/St. Anthony area,
including replacement of municipal wells in New Brighton and St. Anthony and
the initiation of a region-wide comprehensive study. of the contamination,
called a Remedial Investigation/Feasibility Study (RIfFS).
The major suspected source of contamination of the area is the U.S. Army's
TCAAP facility. Also beginning in 1981, the U.S. Army began its own
investigafion o~contamination at TCAAP, with the assistance of Honeywell,
Inc., which operates a facility under contract at TCAAP. The U.S. Army's
investigation, until recently, has been loosely coordinated with HPCA and U.S.
EPA.
Although the U.S. Army has taken some steps to address the problem
(beginning in 1983 the U.S. Army began supplying bottled water to six
'residences adjacent to the southwest boundary of TCAAP. Subsequently, these
. residences, along with others in the area, have been connected to municipal
water systems), the general public and elected officials have been vocally and
consistently negative towards the U.S. Army's e.fforts. The public feels that
'-~he U. S. Army has attempted to conceal the problem and avoid res pons ib'qity.
Beginning in 1984, a series of lawsuits were brought against the u.S. Army by
the Cities of New Brighton and St. Anthony, and a number of citizens living in
the area, for property damage and personal injury. Final outcome of these'
suits is still pending.
- -'The focus of community concerns has been possible health effects from
contamination at tht site, the apparent delays in getting the site cleaned up,
and the role and res~~sibilityof the U.S. Army in addressing these concerns.
."
4
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III.
-3-
SUMMARY OF puaLic COMMENTS RECEIVED DURING
PUBLIC COMMENT PERIOD AND EPA RESPONSES
Comments raised during -the. TCAAP public comment period are summarized
below. The U.S. Army held the public comment period between May 10 and June 1,
1987, to receive comments on the proposed interim action: Phase I Boundary
Ground-water Recovery System, .or BGRS. In addition to the public comment
period, the U.S. Army held a public meeting on Hay 20, 1987 to take comments
and. answer questions. In addition to comments from EPA, the U.S. Army
received written comments from 10 individuals. Four other individuals made
verbal comme~ts only. These 14 commentors, their affiliations, and date and
means of comments are detailed in Appendix A. The comments received during
the comment period are categorized by relevant topics.
A.
B.
Public I nput and Par-ticipation
1)
The Minnesota Pollution Control Agency (HPCA) commented that. the
opportunity for public comment on the BGRS should have occurred prior
to the design of the system so that the system desi~n could take into
consideration HPCA's and the public's comments. .
2)
U.S. EPA Response: Comment noted. U.S. EPA's ROD
the immediate avp.ilability of the U.S. Army system
modifications requested by the State of ~innesota.
"Preserve Our Land" commented that the documents' that the public was
asked to comment on at the Hay 20, 1987 public meeting were not
placed in the St. Anthony Library.until several hours prior to the
meeting, making it impossible to read before the public meeting.
takes into account
and the .
. V~S. EPA Response:
Comment noted.
Application of Feder-al Statutes
1)
Briggs & Morgan commented that contrary to the provisions of Section
117 of SARA, the U.S. Army has not p.rovided an analysis of
alternative proposals that were considered ,and rejected.
Additionally, "Citizens ror a Better Environment" (CBE) commented
that it was not clear what other treatment options were considered.
2,)
U.S. EPA Response: The GRAAA prepared by the U.S. Army did provide
analysis of alternative remedial 'actions. U.S. EPA notes that these
comments are valid for t~e text of the ROD, however, U.S. EPA'is
faced with a comp1eteq system vs. alternatives that would take some
time to complete. Because U.S. EPA has determined that operation of
the existing six wells will provide some degree of protection, it is
advisable to start intercepting contaminated groupd water now and
modify the system as required to provide complete protection of human
health .and ~.environment.
MPCA commented that the Ground Wate~ Remedial Action Altern~tives
Analysis (GRAAA) outlines six ground-water extraction scenarios.
BGRS, as described, does not conform to any of the six scenarios.
Selection of a remedy that was not cli.scussed as an al t'ernative is
in~onsistent with the procedures in CERCLA and the NCP.
The
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.
-4-
U.S. EPA Response: This ROD is the U.S. EPA decision. The proposed
BGRS is different than ihe six alternatives in th~ GRAAA. A decision
different than alternatives is not contrary to statute (CERCLA/SARA) .
or regulation (the SCP). The'U.S. EPA decision is to operate the six
wells as partial fulfillment of the Hillside Sand aquifer gradient
control sy~tem required in Attachment 2 of the Interagency
Agreement. After 90 days from the time of initial operation the
system shall be reviewed for adequacy of control and level of
treatment provided in both the Hillside Sand and Prairie du
Chien/Jordan aquifers, and modifications will be designed,
constructed and operated on schedule.
3)
HPCA commented that the BGRS is a remedial action, and,therefore,
requires the U.S. EPA Administrator's approval.
U.S. EPA Response:
Comment noted and agreed with.
4)
Briggs & Horgan commented that the U.S. Army did not establish a
Technical Review Committee, as provided for in Section 211 of SARA,
to review the BGRS.
U.S. EPA Response: A Technical Review, Committee is not required in
every instance, and is not an approving body for Remedial Actions.
Remedial Actions are a joint decision between the federal agency and.
U.S. EPA according to Section 120 except in instances of disagreement
where the U:S. EPA Administrator makes the final determination.
However, it is the understanding of U.S. EPA that the U.S. Army does
intend to set up a Technical Review Committee and has begun planning
for one.
5)
Briggs-and Horgan commented that contrary to the provisions of
Section 120 of SARA, neither the City of St. Anthony nor the State of
Hinnesota were invited to participate or included in the planning or
selection of the BGRS.
U.S. EPA Response:
Comment noted.
6)
MPCA commented that the contemplated Phase II and Phase III .
activities conducted by the U.S. Army must be consistent with the
conclusions of the regional MPCA/U.S. EPA RI/FS currently under way
and with CERCLA.
U.S. EPA Response:
be so.
Comment noted.
The Agreemen~ ~ill ensure this to
7)
MPCA commented that it does not agree with the U.S.. Army's
interpretation of factors applied in selection of Applicable or
Relevant and Appropriate Requirements (ARARs). ' As stated in CERCU
Section 1'20(a) (2), "all guidelines, rules, regulations and
criteria...~~licable to remedial actions...sh4ll also be applicabl~
to facilities which are owned or operated by...the United States..."
.-
U.S. EPA Response: The U.S. Army decision relied only' on promulgated
rules that are legally applicable. The correct interpretation is
that guidelines, rules, regulat~ons.and criteria may be relevant and
appropriate even if not legally applicable~
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c.
'.
-5-
8)
MPCA commented that ARARs appiy both to treatment prior t~ discharge
and ground-water cleanup.
U.S. EPA Response: .U.S. EPA agrees with the MPCA comment and has
incorporated it into this ROD.
9)
CBE commented that water quality criteria and ARARs should be
applicable to all phases of the remedial 'action.
U.S. EPA Response: U.S. EPA agrees with the CBE comment and has
incorporated it into this ROD. Drinking wat~r standards ~ill apply
t~ all discharged water. Users of the treated ~ater will be '
protp.cte~ to an even greater degree.
Application of State Statutes
A number' of the comments received regarding the application of state
statutes dealt specifically with State permits regarding the BGRS.The U.S.
Army was granted State permits for the BGRS by the ~finnesota Department of
Natural Resources (MDNR) and ~IPCA. A number of the comments received,
therefore, address the BGRS in reference to these, permits.' The U.S. Army, in
responding to these comments, claimed that because the BGRS ~as a remedial
act jon, it no longer required these permits.
.
The U.S. Army is correct in that remedial actions do not require a, '
permit. However, the remedial action must meet all substantive and procedural
requirements of such permits. In short, all reqirements of a permit must be
met, even though the physical paper of a permit is not required.
Exceptions to meeting the requirements are possible with special notices
to the Sta~e' andother conditions. No exception to the permit requirement is
desired for the Gradient Control System in this ROD.
1)
CBE commented that modification provisions are not specified in the
U.S. Army's propos-ed interim action document. Additionally, ~fPCA
commented that the Army has not submitted documents outlining
modification provisions for ensuring capture of VOC-contaminated
water in other regional aquifers. The National Pollutant Discharge
Elimination System/State Disposal System (NPDES/SDS) Permit
specifically outlines the procedures necessary to address all
regional ground-water contamination emanating from TCAAP.
U.S: EPA Response: This ROD incorporates the same type of provisions
as the NPDES/SDS permit artd the potential need for modifications. A
schedule for modificaiions is- incorporated in this ROD. The
attachment to the NPDES/SDS permit was adopted from the Agreement
then being negotiated. These requirements are now in the signed
Agreeme~t. '
2)
, .
"MPCA comment~that the MPDES/SDS Permit establishes water criteria
for ground-water migrating off TCAAP. The BGRS must be modified,
within the appropriate. time frames to meet these criteria. .-
.
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-6-
U.S. EPA ResDonse: This ROD incorporates the same
as the NPDES/SDS permit and the potential need for
, schedule for modifications is incorporated in this
consistent with that ~n the Agreement.
type of provisions
modifications. A
ROD and are
3)
MPCA commented that the U.S. Army must submit to ~PCA an Air Quality
Emissions Fa~ility Permit Application. MPCA does not view the BGRS
as a separate facility for the purpose of an air quality permit.
Rather, the TCAAP facility includes all air emissions sources,
including the BGRS. The U.S. Army must consider compliance with Best
Available Control Technology (B~CT) to address air emissions from the
TCAAP facil i ty.
U.S. EPA Response: In consultation with ~PCA, this ROD incorporates
provisions for emission controls should the need be dcmonstrate~
based on the initial 90 days of operation.
4)
MDNR commented that it considers the initial 90 days of pumping to be
a test of the system and- the State Permit (HD~R Appropriation Permit
87-6048) will be amended based on the findings of data collected
during this period.
U.S. EPA Response:
Comment noted.
.
5)
The City of New Brighton commented that it supports State Disposal
System Permit ~o.: MN0056952, and ~!D:-"'R Appropriation Permit 87-6048
and believes the U.S. Army should comply with both.
U.S. EPA Response:
Comment noted.
6)
MPCA andrCBE commented that, regarding applicable State standards for
raw water supplies and surface water discharges, it appears ,from
review of the U.S. Army's proposed interim action document that the
U.S. Army has chosen to use only numeric standards from Chapter 7050
and has not addressed the impact of narrative standards in this
Chapter as it would affect ARARs. These narrative sections allow the
MPCA to derive criteria and set standards to protect human health
consumption of water and aquatic organisms, and protect a~uatic life
from acute and chronic toxicity, test impairment and bioaccumulation
in ground water and surface waters as appropriate. These are
essentially the same criteria, which'the proposed interim action
document has identified as relevant and appropriate on page five as
Federal ARARs. MPCA commented t~at any discharge into Rice Creek
would be in direct violation of the NPDES/SDS Permit.
U.S. EPA Response: Comment noted. ARARs are incorporated in with
the capture zone (ground-water cleanup) and discharge requirements of
this ROD. It should be noted that ARARs are minimum standards and
the first priority is the protection of public health and the
environmenr...1..' .
7)
CBE commented that the U.S. Army BGRS needs to comply with:,'.
.
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D.
-7-
HN Rules-Ch. 7050.0210 STANDARDS FOR DISCHARGE TO WATERS OF THE
STATE, specifically Subparts 6, 9 and 14.
MN Rule Ch. 7050.0220 SPECIFIC STANDARDS OF QUALITY ~~~ PCRITY
FOR DESIGNATED CLASSES OF WATERS OF-THE STATE.
~~ Rules Ch. 7060.0600, Subpart 4 Toxic pollutants.
U.S. EPA Response: Comment noted. ARARs are incorporated in ~ith
the capture zone (ground-water cleanup) And discharge requirements of
this ROD. If should be noted that ARARs are minimum standards and
the first priority is the protection of public health and the
environment.
Regional Extent and Responsibility of Contamination
1)
~riggs and Horgan, the City of St. Anthony, Bruce A. Liesch and'MPCA,
all commented that it is arbitrary to assume that the plume of
contaminated ground water only reaches as far as the City of ~ew
Brighton, and that significant data exists to indicate that TCAAP
contamination extends beyond the New Brighton municipal wells.
Several of these commentators go on to say that TCAAP is the source
of a regional contaminant plume that has contaminated wells in St.
Anthony.
.
U.S. EPA Response: U.S. EPA and HPCA agree (with each other) that
contamination is likely/probably extending from TCAAP to the St.
Anthony Are~. Differences in constituents and ratio of contaminants
are found at St. Anthony and may be explained either as a separate
~se o'-'ontamination, or as the U.S. EPA/HPCA believes, these
differences may be explained by degradatipn of compounds and perhaps
comingling of other sources. The Phase I Study is intended to
determine if TCAAP is the source of contaminants in St. Anthony.
Under the Agreement, U.S. EPA and HPCA are the determiners -of the
source of contaminants and will define the plume to be addressed
under the TCAAP Feasibility Study.
2)
Addition~lly, the City of New Brighton and Hr. Fuhr commented that a
comprehensive final remedy requiring regional clean up of
contaminated ground water needs 'to be reached q.uickly.
U.S. EPA Response: U.S. EPA agrees, however, a final remedy can be
selected only after c~aracteriz.tion of contaminants and study of
alternatives, as outlined in CERCLA, SARA, and the NCP. This
characterization will occur in the Phase IA Remedial Investigation
conducted by U.S. EPA/HPCA and the on-TCAAP Remedial Investigation
conducted by the U. S. Army'.
3)
Ms. Winiecki~mmented that the BGRS does not address the problem of'
the 14 families who have wells on the east side of Round La~e and
.that sediment in Round, Lake h~s unusually high concentrations of PCBs.
.
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E.
, 1)
-8-
U.S. EPA Response: The U.S. Army has addressed the wells by sampling
wells at the area near Round Lake. The U.S. EPA sewer line pre-study
will be finished this fall and will most likely recommend further
study be undertaken in an RI/FS to address the PCB contamination in
Round Lake.
Bedrock Contamination and Monitoring
Bruce A. Liesch commented that ground-water contamination has
occurred from migration of contaminants through the bedrock system
and a bedrock 'recovery system should be installed immediately to
intercept it.
U.S. EPA Resoonse: The U.S. EPA and ~PCA analysis does not show
sufficient protection of the bedrock (Prairie du Chien/Jordan) .
aquifer by the U.S. ~rmy's proposal. However, benefits from the
,operatio~ of the existi~g system do not w.rrant waiting to construct
~ bedrock capture system. This ROD is to operate the existing system
and plan modifications using operating data from the first 90 days to
adequately protect both the Hillside Sand and Prairie du Chein/Jordan
aquifers.
2)
druce A. Liesch commented that the proposed bedrock recovery system.
proposed in the Ground Water Remedial Program Plan (GRPP) does not
include recovery of the south plume as defined by HPCA in the
Multi-Point Source RI. Without interception of the south plume, a
bedrock plume will continue to migrate from TCAAP, even after the
TGRS is fully implemented.
U.S. EPA Response: The south plume is primarily within the Hillside
~and aquifer at the boundary of TCAAP. The existing six well system
will i~tercept the migration of the VOC contamination. After the
first 90 days the system will be modified to insure the adequate
protection of both the Hillside Sand and Prairie du Chein/Jordan
aquifers. '
3)
Bruce A. Liesch commented that the U.S. Army proposed to determine
'the need for bedrock recovery wells along the southwest TCAAP border
based on the drawdown influences in the bedrock fFom BGRS pumping.
To do this a series of well nests would need to be present to
determine the hydraulic response in the upper, middle and lower units
of both bedrock ,aquifers. This .is needed to observe how deep ~he
hydraulic response from the BGRS system operation propagates. The
City of St. Anthony adds that it is unclear whether removal of
contaminated water from deeper aquifers and upward draw can be
accomplished through the BGRS, and, further there is no means to
verify whether ~his is taking place.
U.S. EPA Re~ponse: The existing monitoring network is adequate to
demonstrat~~. adequate upward draw from 'bedrock exists. U.S. EPA
expects that the firs~ 90 days of operation and data.collection will
demonstrate that modi(ications will be needed (e.g.. if bedrock
extraction wells need to be constructed and operated).
4
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F.
-.
'-9-
Monitoring of BGRS
1)
The City of New Brighton commented that it is crucial that monitoring
be able to determine whether the system is effectively intercepting
contaminated ground water above the concentrations of concern
established by U.S. EPA and MPCA. Such a monitoring program should
include:
a)
The ability to determine the j-dimensional capture zones for
individual extraction wells and the gradients control system
collectively;
b)
The ability of the gradients control system to respond to
short-term and sea$onal changes in the ambient hydraulic
gradients; and
c)
An ability to locate down gradient monitoring points that can
demonstrate that no contaminated ground water is bypassing the
gradient control system.
U.S. EPA Resconse: U.S. EPA has addressed these concerns in this
'ROD. . U. S. EPA fee ls the total system performance (as opposed to
individual wells) is the most important monitoring requirement. The
monitoring system will reflect vertical as well as horizontal
performance and reflect seasonal fluctuations in the first year.
Planned quarterly monitoring may be modified if short term changes in.
the first year require more frequent monitoring in the future.
2)
.
This monitoring will be performed by the U.S. Army under review, and
QUersi~ by MPCA and U.S. EPA.
Mr. Fuhr commented that the BGRS should be monitored continuously by
an outside party, preferably MPCA.
U.S. EPA Response: U.S. EPA feels that the planned first year
monitoring of the system should be sufficient to evaluate tot~l
system performance, as well as determine the frequency of monitoring
necessary in subsequent years. The monitoring will be performed by
the U.S. Army under review and oversight by MPCA and U.S. EPA. Under
, the Aareement the costs of oversight are reimbursed by the U.S. Army.
G.
Effluent Discharge Issues
1)
The City of New Brighton commented that the treatment
meet discharge limitations on a consistent basis. An
monitoring of the gravel pit discharge must include:,
b)
system needs to
effective
a)
A detailed, water balance of the TCAAP area;
&~. '
Ground-water quality downgradient in ,all directions of the
gravel pit dischat'gej .'
c)
On-going monitoring of hydt'aul\c gradie~t response to the
recharge in the vicinity of thl kame; and
. ,
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,~
-'."---
-10-
d)
~onthly water quality monitoring until the boundary gradient
control wells are intercepting effluent-derived ground water.
U.S. EPA Response:. A,detailed water balance based on calculated
values will be required within 30 days prior to operations.
Periodically thereafter, based on actual operation data, a water
balance will be required. Ground-water quality and gradient
monitoring will be required as part of the operation of the systems.
2)
HDNR commented it continues its support to use the gravel pit for
discharge as a reasonable use of water and as a water conservation
measure.
U.S. EPA Response: Comment noted: ender this ROD the gravel pit
will.be the normal discharge point for BGRS-treated water that i~ not
used for in-plant use.
3)
HD~~ commented that any discharge of treated water to Rice
reduces the cost-effectiveness of the Rice Creek Watershed
work, in particular their efforts to reduce phosphorous
concentrations, would not be supported. '
Creek that
District's
U.S. EPA Response: The discharge to Rice Creek is allowed and notice.
is given in this ROD. Discharge requires that nutrients including
phosphorus may not be increased from current loadings in Rice Creek
as it enters TCAAP. Discharge to any surface water, including Rice
Creek, may not occur except in a manner acceptab'le to U. S. EPA and
MPCA.
4)
!he Cit.il-of New Brighton'commented that the possibility exists that
effluent discharge into Rice Creek ~ould improve water quality in
Long Lake, and therefore, the possibility of discharging effluent
into Rice Creek should be retained. while the concentration of
Hillside, Sand gr~und water is studied more thoroughly.
U.S. EPA Response: This ROD allows that discharge to Rice Creek is
allowed if required and notice is given. Discharge requires that
nutrients including phosphorus may not be increased from current
loadings i~ Rice Creek as it enters TCAAP. The possibility of
improving water quality through dilution with treated water can be
considered in the future using data collected in earlier phases of
operation.
5)
Mr. Fuhr commented th~t there is a' need to be very careful about any
discharge into Rice Creek because it eventually flows to the
Mississippi River, which is a major source of drinking water in the
area. ' .
U.S. EPA ReiPonse:' Comment noted. This ROD allows discharge to Rice
~. .
Creek or other surface waters only after treatment and an acceptable
monitoring plan is in place to prevent the discharge of contaminants
or nutrients to any surface water including Rice Creek. Thi
discharge to Rice Creek must be acceptable to U.S. EPA and MPCA.
.
-------
-11-
6)
CBE commented -that the impacts of high manganese levels should be.
assessed before any effluent is discharged in Rice Creek.
U.S. EPA Response:' Comment noted. This ROD allo~s discharge to Rice
Creek or other surface waters only after treatment and an acceptable
monitoring plan is in place to prevent the discharge of. contaminants
or nutrients to any surface water including Rice Creek.
H. . Contingencies
1)
~PCA commented that it wished to kno~ the U.S. Army's plans shcu:d
the BGRS have a breakdown.
"
U.S. EPA Response: The operating conditions in this ROD ensure the
BGRS will not operate unless an acceptable treatment system is in
operation prior to disc~arge. The system will be shut down
completely for repairs or during emergencies.
2)
HDNR commented that a question has arisen concerning the timing of
the installation of additional remedial measures. If the testing of
the system shows. for example. that sufficient "upwelling" from the
Cnit 4 aquifer is not occurring. will the U.S. Army be able to
install an additional well or wells this year or will the U.S.
have to wait for another budget cycle to get the funding. Any
in improving the system. if it is sho~n to be necessary. would
in the mutual best interest of the U.S. Army and the State.
.
Army
delay
not be
U.S. EPA Response: The U.S. Army has made assurances that funds are
available and no delays will occur due to budget cycle constraints.
. I.
Health lssues
1)
~!PCA commented that it is unclear how the U.S. Army can assure that
air emissions from the BGRS and other TCAAP sources not adversely
impact human health. welfare and the enviro~ent.
U.S. EPA Response: No acute or chronic health problems are
anticipated. After the first 90 days of operation. U.S. E~A will
conduct a study to determine if emission control is required. The
air emission requirements and monitoring is sufficient to protect
public health.
2)
Briggs & Morgan commented that the U.S. Army has not proposed a
program to monitor the health of the citizens.
U.S. EPA Resconse: There are several studies currently under way
which address the health concerns of citizens in the area. First, as
Senator Novak explained at the May 20. 1987 public meeting. the
Minnesota Department of Health will be conducting a state-wide cancer
surveillancJL~~dy which will place a special emphasis on area~ such
as New Brighton and St. Anthony where an environmental event may have
occurred. Additionally, a public health evaluation is being
.
-------
J.
-12-'
conducted by flPCA ~s part of their comprehensive study of
ground-water contamination in the ~ew Brighton/Arrden Hills/St.
Anthony area.
The Agency for Toxic .Substance and Disease Registry (ATSDR),
established in CERCLA and given additional duties under SARA, is to
perform a health assessment at each facility on the National
Priorities List (NPL) prior to December 10, 1989. Work on the TCAAP
area assessment is in a preliminary planning stage. On Hay 18, 1987
ATSDR received a citizens' petition from the Village of St. Anthony
and 14 individual families asking that the TCAA? area assessment be
given priQrity.
3)
Hr. Fuhr commented that a third party should conduct a health study
on people living in the area over the past 30 years. Similarly~
"Preserve Our Land" commented that any health study conducted should
encompass the area affected by the "contaminant plume" as identi'fied
in the Volume I Work Plan of ~PCA's regional study.
U.S. EPA Response: As noted in the previous response, ATSDR, HDH and
HPCA are conducting studies ~hich will address both of these concerns.
Specific Comments On Facts and Language used in the Army's Proposed
I nterim Action Document
.
1)
The Hinnesota Department of Health (MDH) commented that the statement
"There are no existing Minnesota drinking water standards and
criteria which are legally enforceable" contained on page six Under
the section entitled Raw Water Supply is incorrect. Minnesota Rules,
Chapter 4720 contain legally enforceable drinking water standards
applicaDle to public water supplies.
U.S. EPA Response: MDH is correct. Currently, however, there are no
enforceable standards for some VOCs. Therefore, for those
contaminants where no Maximum Contaminant Levels (MCL) exists,
non-zero MCLGs, Health Advisories, or other criteria will be used.
2)
MPCA commented that i~s comments on the BGRS were not eval~ated
and/or incorporated into design and construction of the system.
u.s. EPA Response: U.S. EPA has worked with MPCA in developing the
requireme~~~ for operation in this ROD. Hodifications to the ~ystem
will b. submitted by the U.S. Army before the l50th day of operation
and subject to acceptance by both U.S. EPA and MPCA.
3)
HPCA commented that on-TCAAP regional monitoring wells located down
gradient of disposal sites have shown VOC-contamination at levels in
excess of 40.2pm~ private w~lls located immediately adjacent to an
downgradient of TCAAP have VOC-contamination levels in excess of
. ,
7 ppm. Th~~~or8, the U.S. Army s references to low contaminant
levels is in error. .
.'
U.S. EPA Response:
HPCA is correct.
.
-------
-13-
4)
NPCA commented that previous interim response actions to provide
potable water to residents of Arden Hills, Sew Brighton and St.
Anthony were provided by EPA-and/or MPCA. Additional response
actions are underway to provide or maintain adequate drinking water
supplies in New Brigh~on and Arden Hill~ as a result of the regional
ground-water contamination. Also, it should be noted that the
Mingelkoch & Gordon Rendering Plants are using bottled water for
.drinking water supplies due to the regional contamination.
Therefore, the U.S. Army's statement regarding available alternative
water supplies is misleading.
U.S. EPA Response:
~IPCl\ is correct.
5) .
that the U.S. Army states that "there. are hazardous
no known pollutants or contaminants, as defined by
the boundary." MPCA disagrees with this state.ment
dafinition of "pollutant or contaminant" does include
substances found migrating from TCAAP. These .
~no~n or suspected cancer-causing compounds.
~fPCA commen t ed
substances but
SARA, crossing
given that the
'several of the
substances are
u.S. EPA Response: u.S. EPA is in
it has been incorporated into this
in category of substances makes no
remedial action.
agreement with this comment, and
ROD. Additionally, the difference
difference in developing a -
..
6)
MPCA & CBE commented that Minnesota Water Quality Standards are now
found in Minnesota Rules, Chapter 7050. Similar incorrect citations
are to be found on page six of the U.s. Army's proposed interim
actiQn document.
u.s. EPA Response:
Comment noted.
7)
CBE commented that the table of standards for Rice Creek is
incomplete and at least should include the total chromium value of
. .05 milligrams per liter (mg/ l) .' .
u. S. EPA Response: This value will be incorporated in t.he criteria
values and limits for discharge if a discharge to surface w~ters is
requested.
8)
CBE commented that it is a contradiction to state that there are no
Federal or State ambient air quality standards applicable to ths
emission of vacs from the BGRS arid to then state the BGRS VOC air
emissions are below any known regulated levels.
U.S. EPA'Response: Comment noted. The air emission regulations for
vacs only app1y.to cases where'combined emissions total more than 25
tons per year. Control requirements may be applicable (such as Best
Avail~ble Control Technology) and will be evaluated during the first
90 days of ~eration. .
~.
-
.
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K.
'-'
-14-
9)
The Metropolitan was~e Con~rol Commission commen~ed ~ha~ the U.S.
Army's proposed interim action document did not address the
maintenance of the BGRS air strippers, specifica1ly any bypass to the
sanitary sewer.
U.S. EPA Response: Any discharge to the sewer will require prior
approval by the Metropolitan Waste Control Commission.
Selection and Application of MCLs
1)
HDH commented that the estimated TCE intercept level of 10 ppb from
the Hillside Sand and Prairie du Chien/Jordan aquifiers a~ the
southwest boundary of TCAAP is unacceptable. EPA has proposed an MCt
for TCE at 5 ppb, and it is~IDH's position that the BGRS must
intercept TCE 'at levels not 'exceeding 5 ppb.
U.S. EPA Response: This ROD requires a capture criteria
ppb or better. Additionally, other substances will al~o
to insure that no risk occurs from substances other than
Table 1 for criteria levels.
for TCE of 5
be monitored
TCE. See
2)
Bruce' A. Liesch commented that the proposed system allows VOCs with
concentrations that exceed 10 ppb, to move past the north and south.
borders of the ground-water recovery area.,
U.S. EPA Response: The system will be operated for 90
ground water contaminated with VOCs in excess of 5 ppb
captured, modification~ to ensure adequate ~apture are
days. If
is not
required.
3)
MPCA commented that the U.S. Army states the "BGRS System ... is
expect~ to achieve a zone of capture to 10 ppb TCE at the southwest
boundary," however, HoneY\Jell's April 27,1987 written comments to
MPCA contradict this statement. HoneY\Jell estimated that (1) 100
percent removal of VOCs from Unit 3, and (2) 25-100 percent removal
of VOCs from Unit 4 would occur.
U.S. EPA Response: The system will be operated for 90 days. If
ground water contaminated with VOCs in excess of 5 ppb is not
cap~ured, modifications to ensure adequate capture are required.
4)
MPCA commented that Section 120 (d), of CERCLA requires the attainmen~
of MCLGs including 2.8 ppb for teE. It is unclear, ~herefore, how
the 10 ppb TCE aquifier cleanup 'level was developed and chosen'since
a health risk assessmen~ was never conducted at TCAAP.
U.S. EPA Response: This ROD requires clean up to the MCt for
constituents, such as trichloroethene and vinyl chloride tha~ have
MCLs es~ablished. MCts are, the standards used for municipal drinking
water suppites'. .Some constituents of contamination do not have MCts,
50 other stah~ards are used. The criteria values are given in
Table 1 of this ROD. Users of water:will be p~otected.to U.S. EPA's
public health criteria. ,-
4
-------
L.
3)
-15-
5)
In a follow up comment, ~PCA added, that it is apparent from the U.S.
Army's proposed interim action document that the U.S. Army intends to.
have standards applied to the BGRS trea~ment system only and will
dispense with cleanup standards for the affected aquifier until such
time as a health risk assessment is completed through the RIfFS.
U.S. EPA Response: Plume capture criteria are drinking water
standards. Additionally, receptors will be protected to a greater
degree. This approach assures that the ground water leaving TCAAP
the southwest boundary is appropriate for drinking water aquifers.
at
6)
C.BE commented that since TCE and other VOCs are not naturally present
in the affected aquifers. no' amount should be left in the system. .
U.S. EPA Response: No method of ground-water treatment can assure.
contaminant free ground- water once it has been contaminated.
However. criteria levels set forth in this ROD will achieve a safe
drinking water supply in both aquifers.
Other- Comments
1)
Senator Steve Novak commented that the ~finnesota legislature had
recently apprapriated funds to the State's Attorney General for the
purposes of a lawsuit should the site not' be cleaned up in a
satisfactory manner. Senator Novak noted. however. that he hoped
that the State. U.S. EPA. the U.S. Army. and the local community
could work together to resolve the issue. and that a lawsuit on the
par~ of the State would only be used as a last resor~.
.
U--S. EPA-Resoonse: The'Agreement between U.S. EPA. HPCA. .and the
Army. as well as the provisions of CERCLA. SARA. and the SCPo ensure
that bo~h the State. through HPCA (a party to the Agreement). and the
local communities through the public participation requirements will'
have input into any final decisions m~de. and that the investigation
and remediation of the site will take place in a timely manner. The
U,S. Army is currently establishing a Technical Review Committee to
further local involvement.
2)
Every commentor ~oted tha~ the problems associated with TCAAP have
been known for a number of years and that the U.S. Army was not
responding to the problem with sufficient speed. All commentors
urged that the process be speeded'up.
U.S. EPA Response: The Agreement between U.S. EPA. MPCA. and the
U.S. Army. as well as the provisions of SARA. call for a timely
remediation of the problem. and U.S. EPA believes thatcl~anup
efforts at TCAAl will move forward in a timely manner under these
provisions. The Agreement allows for ov~rsight of Army Actions and
consistencY~.h U.5. EPA and MPCA standards.
Bruce A. Liesch commented that the BGRS should be expanded laterally
to lntercept ground water exceeding established or proposed drinking
water criteria.
.
-------
-16-
U.S. EPA Response: The requirements for capture is based on drinking
water standard when' such standards exist. If lateral (or vertical)
expansion is required to meet criteria, mo~ifications will occur.
4)
The City of New Brighton and CBE commented that a final remedy
be reached ~ith the appropriate input and oversight from all
concerned regul~tory agencies and affected parties.
must
U.S. EPA ResDonse: The Agreement between U.S. E?A, ~PCA and the
Army, as well as the provisions of CERCLA, SARA, and the SPL ensure
that a full community relations program ~ill be implemen:ed. The
Agreement allo~s for oversight of U.S. Army Actions by C.S. EPA 'and
HPCA and consistency with U.S. EPA and MPCA standards.
5)
"Preserve' Our Land" commented that Honeywell was the main polluter at
the facility and they should be made to bare th~ brunt of the cleanup
costs.
U.S. EPA ResDonse: The goal of the Superfund program established by
Congress is to protect public health and the environment. A tool
given to EPA ~as joint and severe liability. A~ federal facilities
EPA holds the "agency" responsible and leaves the contractors
involvement up to the "agency." So "equity" considerations are
required by the Congressional goal.
.
6)
Hr. Myslajek commented that the contaminated ground water should be
left untouched for the next 100 years and the cleanup funds should be
used to draw water from the Mississippi River.
U.s. EPA Response: The provisions of CERCLA and SARA are such that
the feasibility 'study on regional ground-water contamination ~ill
examine the option of not taking any remedial action to clean up
contaminated ground water and will be one of the options the public
will have an opportunity to comment on. .
7)
Ms. Winiecki commented that the families who have wells on the east
side of Round Lake should be furnished with uncontaminated water.
U.S. EPA Response: The U.S.
the area of Round Lake. All
acceptable for potable use.
to the homeowner whose wells
Army tested several resident~al wells in
tests indicate that the wells are
Individual well analysis has been sent
were tested.
8)
The City of St. Anthony commented that the U.S. Army has not proposed
a program to compensate the affected individuals for damage to their
health and property.
U.S. EPA Response:
~~.
Comment noted.
0'
.
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-17-
IV.
REMAINING PUBLIC CONCERNS.
The public took a favorable, if somewhat guarded, reaction to the BGRS.
It is their hope that the BGRS is a first step toward a much-delayed cleanup
of the source of regional contamination. Specific concerns which remain are:
.
The effectiveness of the BGRS and the effectiveness of its
monitorin~ program;
.
The abi Ii ty of U. S. EFA and ~FCA to oversee and moni tot'- the
U.S. Army;
.
The ability for the public to actually have input it the
cleanup process;
.
Inclusion of St. Anthony in the final remedies;
Recaymcnt of pa~t-expenses to affected communities and
families; and
.
.
Health related concerns.
.
~
..~.
.-
/'
.
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'.
..
-18-
APPENDIX A
, "
COMMENTORS ON THE U.S. ARMY'S PROPOSED INTERIM ACTION DOCUMENT
In addition "to U.S. EPA, ther'e were 14 commentators
interim action. Each commentator, and" the .~ay they are
Responsiveness Summary is listed below.
on the Army's proposed
referred to in the
.
State Senator Steve Novak made verbal comments at
the May 10, 1987 public meeting. Comments from
Senator Novak are attributed to him by name.,
.
Barbara Simms, Assistant Executive Director of the
Minnesota Pollution Control Agency, made verbal
comments at the May 20, 1987 public meeting, and
submitted written comments in a letter dated June 1,
1987. Comments from this source are attributed to
the Minneso~a Pollution Control Agency (MPCA).
.
.
Ron Nargant, Director of the Division of Waters,
Minnesota Department of Natural Resources. s~bmitted
written comments in a letter dated June 1, 1987.
Comments from this source are attributed to the
Minnesota Department of Natural Resources (~mNR).
.
David Gray of the Minnesota Department of Health
submitted written comments in a letter dated May 29,
1987. Comments from this source are attributed to
the ~innesota Department of Health (~mH).
.
Peter Berglund, Staff Engineer. Industrial Waste
Division, Twin Cities Area Metropolitan Waste Control
Commission submitted written comments in a letter
dated May 28, 1987. Comments from this source are
attributed to the Metropolitan Waste Control
Commission.,
.
William R. Skallerud, of th~ firm LeFevere, Lefler,
Kennedy, O'Brien & Drawz, representing the City of
New Brignton, submitted written comments in a letter
dated June 1, 19S7. Comments from this source" are
attributed to the City of New Brighton;
.
David M. Childs, the City ,Manager" for St. Anthony
Village, sub~itted written comments on behalf of the
City C~~il of the City of St. Anthony in a letter
dated May 28, 1987. Comments trom this source are
attributed to the'City of St. Anthony.
.-
.
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,
-19-
.
David C: McDonald of the fir~ Briggs & Morgan, on
behalf of the City of St. Anth9ny and various
-families in the St. Anthony area, made verbal
comments at the Hay 20, 1987 public meeting and
submitted comments in a letter dated June 1, 1987.
Comments from this source are attributed to Briggs &
Horgan.
.
Kenneth P. Olson, of the firm Bruce A. Liesch
Associates, Inc., technical representatives to the
City of St. Anthony and select private citizens dOwn
.gradient of TCAAP, made verbal comments at the May
20, 1987 public meeting and submitted written
comments in a letter dated May 27, 1987. o Comments
from this ~ource are attributed to Bruce A. Liesch.
.
Nickalas Tiedeken, a representative of the
organization "Citizens for a Better Environment" made
verbal comments at the ~fay 20, 1987 public meeting
and submitted written comments in a letter dated June
1, 1987. Part of Hr. Tiedeken's statement and
correspondence are in ~he form of questions about
various issues associated with TCAPP, rather than
comments on the proposed interim action. Comments. on
the proposed interim action have been incorporated
into the Responsiveness Summary. Hr. Tiedeken's
comments are attributed to "Citizen's for a Better
Environment" (CBE).
.
Gary .Payne, a citizen of Hinnesota, and a
representative of the organization "Preserve Our
Land" made verbal comments at the Hay 20, 1987 public
meeting. Additionally, Robert Lohman submitted
written comments on behalf of "Preserve Our Land" in
a letter dated April 29, 1987. Part of Hr. Lohman's
correspondence is in the form of questions about
various issues associated with TCAAP, ra~her than
comments on the proposed interim action. - Comments on
the proposed interim action have been incorporated
into the Responsiveness Summary. Hr. Payne's and Hr.
Lohman's comments are attribut.ed to "Preserve Our
Land."
~
.
Jerry Fuhr~ a ci~izen from New Brighton, made
verbal comments at the Hay 20, 1987 public. meeting.
Comments from Hr. Fuhr are attribut.ed to him by name.
.
John Myslajek made verbal comment.s at the Hay 20,
198; publ~c meeting. Comments from Hr. Hyslajek are
attri!:lln8d t'o him by name.
.
Jeanne Winiecki, .a citizen
verbal comments' at the Hay
Comments from Ms., Winiecki
name.
of Arden Hills, made
20, 1987 publi~ meeting.
are. attributed to her by
.
.-
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ARARs
ATSDR
BACT
BGRS
CBE
CERCLA
GRAAA
GRP
GRPP
~fCL
MCLG
-=-
HDH
~IDNR
MPCA
MWCC
NCP
NPDES
NPDES/SDS
PCBs
pp~
ppm
RIfFS
ROD
SARA
-20-
APPENDIX B
DEFINITIONS.
Applic~ble or Relevant and Appropriate Requirements
Agency for Toxic Substance and Disease Registry
Best Available Control Technology
Boundary Ground-Water Recovery System
Citizens for a Better Environment
Comprehensive Environmental Response Compensation and Liability
Act of 1980
Ground water Remedial ACtion Alternatives Analysis
Ground water Remedial Program
Ground Water Remedial Program Plan
Maximum Contaminant Levels
.
~!aximum Contaminant -Level Goals
Minnesota Department of Health
Minnesota Department of Natural Resources
~1innesota Pollution Control Agency
Metropolitan Waste Control Commission
National Contingency Plan
National Pollutant Discharg~ Elimination System
National Pollutant Discharge Elimination System/State Disposal
System
Polychlorinated ~iphenyls
Parts per billion
&~.. .
Parts per million
Remedial Investigation/Feasibility Study
0'
Record -of -t)ec is ion
.
Superfund Amendments and Reauthorization Act of 1986
-------
TCAAP
TCE
TGRS
U.S. EPA
VOC's
.
-21-
Twin Cities Army Ammunition Plant
Trichloroethylene
Twin Cities Army Ammunition Plant CTCAAP) Ground-water Recovery
System
united States Environmental Protection Agency
Volatile Organic Compounds
.
..~.
.-
.
-------
ATTAr.H"1F:~H 3
. .
PART A
q~r.IITIVI: SII"1"1AQV anrl CHAPn:q n
.
fro",
r,Q(')IINn\.lATEQ RF."1~nIATInN PR(')r,RA~ PLAN (r~RPP')
JIINF: lqRn
-
..~.
.
-------
,
EXECUTIVE SUMMARY
Volatil~ organic compounds (VOCs) ar~
prese~~
in TCAAP groundwater.
As a result of this
presence, a
commitment has be~n made 'to remediate TCAA? groundwat~~.
Remediation of TCAA? groundwate~ will be done
by installing a contaminated groundwater recove~y sys~sm ar.d
a treatment system.
Grour.dwater recovery involves the
installation of a ser:es of recovery wells desi;r.~d to
~
collect co~taminated'groundwate~.
Treat~ent alternatives involving air
strippin~and granular activated carbon (GAC) technol=gies
were evaluated in conjunction with treated water end-use
alternatives.
Air stripping is demonstrated to be the
appropriate treat~ent technology for groundwater remed~ation
at TCAAP.
Treated water would be used as a TC~.? raw wate~
supply in conjunction with al~ernative end uses of treat~d
water return' to contamination source areas, recharge to
Arsenal Sand and Gravel pits or surface discharge.
~~.'A'Groundwate~ Remediation Program Plan (GRPP)
has been prepared and,the plan recommends implementa~icn in
,
three stages:
.
-------
.
Boundary Groundwat:r Recovery Syste~
(3GRS) operated at
an estimated 750 gpm is intended to be constructed and
operated in-1986.
.
TCAAP Groundwater Recovery System (TGRS) operated
at an
estimated 1275 gpm, represents an expansior. of the BGRS.
.
The TGRS is intended to be constructed and operated ,~
1987.
.
Plume Groundwater Recovery System (PGRS).
T~e size and
cost of the PGRS is determined by the exte~t of the VOC
p1um.e and remediation criteria.
The PGRS is
intended be
constructed and operated in 1987.
.
. -
..... .
.
"
-------
~
6.0
1'..-.......... .... .-
_.'--~-'
-
. -.' .' "L
-. ..... - 0-
CONCEPT (TASK 5)
6.1
BGRS
" Plan 3 presents a conceptual layout of t~e
BGRS summarized as follows:
" "
- recovery of groundwa~er at
sou<:hwest
bou~dary of TC~~?
from 'six Hillside _recovery wells at a total estimated
rate of 750 gpm (1.08 MG~);
.
- twelve water level monitori~g well nests construc<:ed
along the site boundary which in conjunction with
existing wells will be used to demonstrate" the hydraulic
effectiveness of the recovery well~;
- collect and transfer contaminated water to a communal
treatment plant located adjacent to the existi~g TCAAP
potable water treatment plant (Building 116)}
treat water:
- supply an average of 0.57 MGD of treated water as a
potable water supply to TCAAP;
...~ .
- injec<:
an averace '0: 0.51 ~GD of
- .
.-
treated water
to the
...-. ... '"
:=.:~_s~=e
-="u'-..:. ~-~.:.: ,-.,
.-"- - -- -- ---
ar:.ci I G '; ar:.ci
aquifer a:
Sand
-------
~ four water level moni~=ri~g wells constructed near the
source areas to monitor t~e head build up resul~ing from
the injecti6n bf treated water.
6.1.1
Groundwate=
Recove=v/lniec~ion
.. -
Six Hill"side Sand aquifer recove=y wells are
proposed at locations shown on Plan 3.
All recove~y wells
will fully penetrate the Hillside Sand aquifer.
Figure 6.1a
provides a typical sketc~ 0: a recovery well f~lly
penetrati~g the Hillside aquife=; while a schematic of an
.
injection well .is shown on Fig~re 6 .l~.
A cross-section (Figure "6.2) constructed
--
along the southwest site boundary approximately nor~al to the
direction of groundwater flow, shows the proposed recove=y
wells a~on9 with the pumpi~9 water-level resulting from
system operation.
Figure 2.4, previously prese~ted- i~
Section 2.0, locates the cross-section..
Because of t::e
vertical scale employed, the"drawdowns illustrated on.
Figure 6.2; are exaggerated to demonstrate the
conce?~ual
effect of pumping.
..~.
"The ~GRS concept establishes a mi~i~u~ ~umber
of recovery wells at. six.
3ased on available
'-'/c'";':c''';''' ,..,c; C
~l.. -'>.J_-..,,--.-
.
-------
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UN I{ . 2 't.:- 'I:~ ~ROU-
, .' ~:. " .r \; -, -~ -=
--------' ..~~8I:.N,\,;NI,;, P!..:JG
A 'I '
I -1- ~ !: :[ 1 2"'J eC~S~CL~
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. U 8'''1 STE~L C.;S 1 ~jG AND
I "
, 11 STA I NL£SS SiEE!.. I~E!..L SC::<£E~J
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W~E~E THE UNIT 2 TILL 15 A8SE~T rUE
8CREHOLE WILL 8E CCMPL::7EJ WI7HCU7
THE 12"G c;ASING AT SURFACE
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figure 6.1 a
CESiGN OF FUL L Y
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figure 6.lb
SCHEMATIC DESIGN OF, UNIT - 3 INJECTION WELL
G H au N D ~ AT E n n EM [0 I J\ T ION P J1 OG n J\ r~ f> LAN
Twin Cities Army Ammunilion !J/onl
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.
figure 6 2
CROSS - SECTION - 'BGRS
GROUNDWI\TER REMEDIA r'ON PROGRAM PLI\N
TIt'Ifl CIlIt!5 Army Ammunllion Planl
1-
0-
o
(.'S ""', ,,,,( Il
..
llJ -
l1li£1 I SCHUH
.-------
-.) '...
----
-------
ca.':a ao:
t~e sc~~~west bo~~cary a: !C.~.?,
rec::Jve:::'y well.s
wo'...::=.
initially be s~aced at apprexi~a:e:y 500
fe~t.
The 9GRS was
designed in cor.sicerat.iar. of t~e =es~2.:s of t~e
f~-"'s'; '-; 1; ~..
-- -"""". --:
s~~dy re~rese~~ee by t~e G~~~~ (S:S 1986).
The c::Jm~L:~e:::'
. 1
moc e_,
GECF!.:W,
utili=ed
i~ t~e G?~-~~ was ~see
'r.e:::'ei:1 to
t~eore~ically c=r.~i:::,~ t~e zer.es
c: g=:>ur:c'Nat ==
c:ap~:"::-e a~= ~~
select
i~i~ia:
l=~mp:!.::s
:'ates.
T~:s ~ork involved pL:~~i::g
scena::as 0: t~e 9GRS a~ rates 0: :CO Sl=~ a~= lOCO
g~~r.
'T"he
results 0:
t:-.e :oIocel i::S
l~C:!.C3.~e
t:'at t:~e
8GRS
fNO~:C
e :: : e = ~ i 'J e 1 y
capt'..J:,e
g==~~cwa~:~ wi~~i~ t~e
c:=r:t3.~i::a~:c
Fcr~:an
of t:'e ~i~:::=e Sa~= asu::er.
;'.s
.
rec~g~:zec i~ :~e GR)~-~,
ir.he:::'e~:
:.ssumt=::!.or.s
to model:'::;
s~c~ as ~ i :
-------
...
aquifer will be evaluated to determine the potential
value of co~structing par~ially penetrating recovery
wells to provide selected vertical control on
. groundwater capture.
( 3 )
A pumping test will be conducted at B4 on t~e
er:~:.=e
thickness of the Hillside Sand aquifer.
Aquifer
response would be monitored.
(4 )
Based on the results of pumplng
tests
conducted at 31
and B4,
t~e design (spacing, screened
interval a~d
.
. initial pumping rate) far recovery wells B2 ar.d 95 wo~ld
be finalized and these wells installed.
( S )
Pumping tests would .be conducted at all four
rec~very
~
wells to monitor aquifer response.
( 6 )
Based on the results 0: the pumping test for recovery
wells', Bl, B2, B4 and BS, the design and constr~ction ot
recovery wells B3 and 86 would be conducted.
It i~ rec~g~ized that the pumping tes~s
conducted under the BGRS pragram may identify the necessi~y
for additional .r~covery
..~.
by hydraulic monitoring
wells.
T~is need would be determined
of the SGRS with additional wells
0-
added under the TGRS =r~cr~~.
~ -
.
-------
. .
--.-
At this time,
i~ is estimated that the BGRS
system will be .Rumped at a total recovery rate of 750 gpm.
The final BGRS pumping rate will be determi~ed followi~g
evaluation of test and performance data generated
du=-i:lg
well
field opera~ion.
The performa~ce of the 3GRS will be moni~~red
by water level measurements obtained from hydra~lic
monitori~g wells strategically located and from existing
monitori~g wells as shown pn Plan 3.
Flow ra':es of
i~dividual recovery wells will be controlled to e~sure th~
opti~al hydra~lic pe:formance of t~e syste~ is achieved.
In
addition, VOC levels will be determined by sa~pli~g
monitoring and recovery wells.
~
Submersible pumps will recover groundwater at
nominal pumplng rates of 25, 7~ a~d 150 gpm or greater, if
.required.
Flew rates will be controlled by .valves .and
monitored individually at each well.
T~e pumps will be
controlled from a control center located at the treatmen~
plant.
6.1.2
COLLECT.:;: ON
4.~. .
Plan 3 prov~des a layo~t of
.
the ;rou~d'..ia:.:=
. . .
c': -- =':~: :.::
:3 :,. ~:. =::': .
-------
A ground',.;a-ter
c~lle~tion header will be
installed to collect water from the BGRS. rec~very wells.
The
header will be inst~lled along the line of the recovery wells
,
with provisions
to c~lle~": water
from the TGRS boundary
recovery wells.
The colle~ted water will be
transferred
from
the collection header to~the ex:sti~g inac":ive TC)~? raw
water
line which prese~tly is
c~mplete t~ and through the
TCAAP potable water
treat:ne!'lt
plant.
The raw
water li~e will
be modified to suit
t~e ai=
s~rip9i:lg
equipmen~
t~ be
1ccat ed
beside the treat:ne!'lt
....., .::a """'-
;:---......
.
6.1.3
TREATME~T
-,:.
An initial c~mposite water quality profile
for potential TCAA? gr~undwater c~ntaminants listed in Table
2.2. of Section 2.0 was developed for the SGRS and'is
presented in Table 6.1.
This profile was developed in
consideration of rec~mme~ded ~elative pumping rates
a~~ using
existing water quali~y
data.
..~.
.
\
-------
,i
"
...
TAB LE 6. 1
ESTIMATED', INITIAL WATER QUP-.LITY PROFILE - BGRS
Parameter
Estimated Influent'
C ' a
oncentratlon
Ora.anics
trichloroethylene
1,1,1 tri~hloroethane
cis-1,2-dichloroethylene
trans-1,2-di~hloroethy1ene
l,l-dichloroethylene
1,1-dichloroethane
methylene chloride
chlorof:>rm
1,2-dichloroethane
1,1,2-trichloroethane
benzene
carbon tetrachloride
tetrachloroethylene
acetone
di-n-octyl-phthalate
842
173
75.5
38.3
, 27.9
49.1
11.~
6.1
0.25
7.7
2.8
0.3
17.7
15.8
b
.
Metals
mer cury ~
cadmium
lead
nickel
<0.4
2.6
0.5
10.8
General Water Qualitv
.
calcium (:ne/L)
magnesium (mg/L)
iron (mg/L)
manganese
TOC (mg /L) ,
alkalinity (as CaCo3 mg/L)
pH (field)
conductivity (umhos/cm)
temperature (OC)
TDS (:ng/L)
60
28'
0.03
6
2.3
342
7.7
490
13
427
NOTES:
c.......
a
All concentrations in ug/L unless otherwise specified'"
Ins~f~icient data to esti:nat~ i~~lue~: c=nc~ntra~icn
....
-
.
-------
~
..~.
ATT~r.H~F.NT 3
PART ~
CHAPTERS 7 an~ ~ fro~
TWIN ~ITI~~ AR~Y AM~INtTIInN PLANT
r,ROUNn w~T~R R~~F.ntAL Ar.TInN
AlT~RNATIV~S ANALYSIS
.
. .
o
.
",
""
-------
- .
7.a
S~_-\RY Q;:' GROU~D ioiA:'ER RE~J!AL ACT!O~I
ALT-'::RNA:'!\)'::S A~lD r:OS: ANALYSIS
In ~~e following secc~ons, g~Jund wa~~~ r~~ed~al
ac:: ion
al::~:":1a:: ~':~s
a:":
developed ~rom C~e varl~US
~x::'ac:ion sl;~nari
-------
-.
, .
.. .-------------..---------
i-:
Sour:~ r~oval alc~rnaciv~s consider~d in c~is study, ~lch~r ~amDL:~: ~r
pare.ial, at'e 4l?plicable. co .any of the combhatl"ns pr~se:1ted in Tab~~
7.t. The primary effec~ is associated wich t~~ duracion requir~d E~r
ground waCdr remediaci"n.
The avai13ble sOIJr;;e remediacion al~~r:'1at:"J'!s
prepared ~y. Weston Cl~8':') includl!s t~~
E~l:.)wi:1g:
.
.
!~-?lace Decdntamination
~~st~ and ~~ntamin~t~d Soil
In-?lace Closure
Land AP?lic3cion/T~~at~~nt
Low Te~peratur~ Incineration
Soil Vaults (7reatme~t)
Ji5posal
.
.
.
.
-
As discussed previously, t!'te selec:ion 0: t',e j)ar:ial sour:~ r~~edia::.on
alt~rnac:,ve is Jased on e9t:imaced :na9S l'J-3d:':1g rates whie:, wouli ~ai:'!-
tain ac~e?table wat:r quali:y at che ~C~~? ,cundary (17 ?pb :~r ::i-
. chlor~ethyl~~e).
C..)nfi~at:>r:' stud:.~s
ar~ :"equir~d
C;J asse:5S ::1~
ae: '..la :
.
mass loadi~g rat~s or the above sour:~ re~ediation
a1 :: e r~ ac i 'J e s .
The unit cosc~ for ground water t:eac~ent were disc~ss~d i~ C~a?ter ,.a
and are a sig:1iEicant part of che cotal re~ediati"n costs.
Co s: s Eo r
t~e S':>~e c~ot dter~atives have !:)een Jeveloped JY weston (:984).
The costs associated wi:h grouna waCdr extraction, conveyi:1g c~ the
treH:':1ent sysc.:!!!1, and dischar6e have ~et!n ~st imaced for ~ach I"J: t:,p
scenarios and are discussed in Append"i."t C.
De"o!~Jpment 0: the.ground water remedial 4c::.on alta:~atb~~ is ,ased
-In sl!lec::io1'\ of t"e more efficienc or econcmi-: "ption 'avai~abt~ :or -!aeh
component.
!'he t"olO source remediati"n ai.~e:"~acives so:!l~.;:~d =.:>r ::,i5
cost campar~son ar~ in-plac~ closur~ and i~-?lace dec~ntaminac~~n.
In-j:)lal:e closur! is l:o:'13ider.ed par:ia~ s~ur:~ r'!!l1ediat~on J~-:3U5~ .
concinued drainagl! :uay oc:.:ur for a ?t!r:.oc 3::~r .r~e!'taq~ is ~li~ina.td..
Futur2 assc!s!lt1t!:1t of th~ r,1t!, conc.:::1i::'1Ci~:1, and .:iur:l::"n of :.,i.3
drai.nage :uav pt!i:ui: C'P-Eir1elUenc of the !%lass :~adir1g rates :;> t:,e a.qui:~r
., "~.' .' .
and should ~~ c:mpar~d :~ t:'t! ass'Jm?~~~:1S Jssoci.ai:e~ ~l:~ :~t! ?~::~~~
SO'Jr;;S! r~!:1t!diat~\J:1 anal:rsl!:3.'
!n ?:lc!-~ec~n:~::1ati~n
/
( i:'lc::;d ~:1'~ ""'1
.
-------
...
'.
,-J
mu~~:-13Y~~ cap ~~ l~~~:
r~'';:13r;~)
L S
in~ended ~~ remove vola~:L~
, oqanil.: compounds E:"'!!I che soLL such ~hat the natural drai:1ag~ a:1d
leac~ing of contamina~ts to the 6~~unc wate~ is significantly r~~uced.
Therefore. it :,as :'e~:1 ass:.mled to' r~pr-=se:1t a:1 esse:'!C ially c:::Im;)l-,!te
'J
source remedia::on ai:~~na~i~~
Eo r ~ h : s s : '.Id? :: ~ c au s e ::I ass
load i:12:
:" 1.: = s
would be ~educ:d at c":e i::!?:emencacion 0: i:-:-o:ace de:;::>ncami:1a~ion
ar.d
wor:< is
anc:.c:.~aced ~J ~e ::~o:e:ed ove~ a ?r:::l~~c:e~ ~eric~ ~~ 3~ c~
-
!!tonths. more ra?id~~ :~a:1 :~e
l~Q-month (:0-~e3r)
period
ass :,r.: ed
: J:-
parcial
sour;; e
r -=!!1~d i at i ,:m .
Both c:::Imbined air scr:?oing and car,on adsorption sys:-=!!ts
an:: air
st=i?pin~ sysc:::!s
hav-=
Jeen evaluated i:1 the
aLternati'l~s
anal::5 is.
:~e
c~bined air s:~:~oi:1~
~r.::! ;;arJon acs~r:)t ion syste!!l c::>uLd
:)rovide ei:h~~
99 ,~ 99.? ?er~en:
e:~i,;:.enc:!. '",hiLe ::'\e air
s:~i?oi~; s?s:e= aL:::I:'!~ ~as
o~l~ ~::>nside~ed :,
:)r,v:.de ?O ~er:~n~
e':::..; :.er.cy.
!)e!1ding: ?il~t
~esc:n\;.
.
T~e most eC:::ln~ll.: ~e~r.s
Eor 1isl.:ha:-g:n9; the t:-eatec
eE:lue:-:t
LS
: h :":' t.:g :,
pe:-c:JlatLon p~nds, aL:;,o~h i:"15~c:ion we:ls
~rovide a pocential bene::':
of accele:-ated re!nediHion and both are utilized i:1 de'Jelvping the
'grou~d water~!n~dial action alte:-nac:ves.
As a res~lt, che more
attractive o~ping s..;~~arios
inc~ude percolacion pones or in~ection
~e~ls and hav~ 'e~n incorporated into the f~nal alternativ~s.
Tab:e
7.2 prese~ts t~e cen aL:ernac~~es deve!ooed from t~ese com~inat~ans
0: ground wac:r ,?~Ol.n~.
ai-cernac ives.
t ~eac:!len: ,
d~s;;har;e. and sour::e 'cont~::>~
- ?
I. -
AL!!RNAT!~~S COS~ CO~PAR!SON
o
C.Jmparison of c~e cost of th~ various
a~ternat:ves ar: based an t,e
present wor:h analysis ~r~sdnted in Appe~dix C.
Tab:e
- ] ,
'. s~ar:zes
the pr~senc wor:, an~:~sis Eor each
a:te~nati~e cons~der~~g a
~(')m~~~e-:
air scripping and C3rJ0!1 a~5vr:)tion syste~ ~Jr a 3n-~ea:- ~aa~ O-'!~:0C ~~
accordance 'Ji:~ ::?A z~ideli.:'\es (::PA, 1°3£.). ~abl~ j.!o ?r:Jv~des a 51=::-
... - .
. ... -. . . .
inary of the a.L:~=nat:':es wnl.C~ ~e~u:re 9~ po!rcent tr~at::1ent ef:~~i:('\.;'.'
;;~nsider:.n~
a~ a:.~
5::::'jCi.~~'
S::H:~
a:~ne,
.~ ~ : e '::'7\ a t ~... ~ s
."n :. ~:: =- ~ c',: ~ ~ ~
.
-------
..
- _..:;.
whi~h requlre cL~anu? periods ~~ exc~ss v~ 31 y~ar3 re::~~~ onl~ :~e
ini~ial 30-year coses, and t~e addi~ional op~~atin~ and main~enance
cose3 Evr the remaind~r' oE'~he cl~an\.1p shaul:: ~I! c:Jnsidca:'~~ .h~n C:J112-
pari~g wi:h alternaei~es h3ving shor:!r durations.
Altcarnati'l!S 1 ,and 2 re:le..:: 6r:Jund wa~~r e:
-------
- -5
A~~~:'~aci'l~s
5 and .,
app~ar s~~gh:~y mo~~
e~onomi~ ~han Alc~r~aciv~s 3
and':' due c-' the :-educed- r1u:::tOer JE ?u:I1?ir16 wells, ~lchough much 0: chis
di:f~r~nc~ is of:s~t J~ i(\~:~~sed c:~a:~~~C co~cs associated wic~ ch~
~ar~er volumes of wac~r.
Al:~t'~aci"es 7 and ~ at''! ide~:ical c., A:~~r(\ac["es 3 and ~ ex;;~?c ~o:
c~e 1dveL
of ::-ea::necK provi::e:: (09.?
per:::e!1d .'
At c ~rnac: i.ve s 7 ar\c ~
ref: ec:: ed
c;,e inc:-~'Uer1:.31 i:1~:eas~ ir\ :1e': present wor:;, associa:~d wi::,
a cr!'!a::ue!1C ;)C'oc~ss at: 9Q.9 percenc e:f~ciency. Alchough t:~is :1eC
pr~ser\t: "JOr::, cost i!1c:e!I1~:1i: is oo'::,e order of SS00,OOO, com?ared c,
c"t31 neO: prase:1c wo:-:'" Eor.A~:~::'~a:i',~s 3 and 4 0: S12,107,I")OI) and
310,013,000, the i(\i:i.a1 c3pi:al costs 3r~ significant and s~outd ~e
~onsidered ~e:Jr~ selec~ion ~: che ;,igher t:-eat~ent: efficiency.
:":1 e uS ~
ac i:1jec:i.on
we : :.s a r ~
re=~'ec:ed in
A!:-t'!r71ati'res q anJ 11,
where
.
che :-equi=e~ t:-eat:uent pro~~.ss e:ficie!1:y is Q9.? perce!1t.
Ex ~ ~ ii~ ': :. J :1
wells a.re 1.Jcatad near svur.;~ areas and _represe!1~ a lower present we::"
~:)st than the ot:ter a1ternati'1es J~c3::.1se -,E :ewer excrac:ion wells. ~
pressuri:ed i.."'tjec:ion syst~!I1 ',",ould be uti.lized for di.scharg~ oE trea:e::!
ef:!ue~~ i:1 ~cerc: with pr,ovi.ding 1'~A.~? peodl.1c:ion wacer,
T:'~at~e::.:
costs are higher :~ao Eor ~he other al:~r~acives due to the hi~~er ~~~i-
c i e !1c:' and Ell.') w rat e .
As shown in 7abLe 7-3, t:te values of Mt pr~se:1t
wcr:h of At~~r~acives 9 and 1~ ar~ 1~ss chan the ochers, ~xc~pt Al:~r-
oac:ves 1 and 1:
Howe'/e:- ,
s~e inconsi.st~!1cy ~~ists in t~i.s ana~ysi3 i:1
~
:hat th~ treac~e!1t ~roc~ss is
,
, d .10-"" I 1 .
shou. meet rlSi< ~vo!..s,
i.~ ~ased on the 10-5 1~ve1,
jesig~ed t~ provid~ an ef:luen: ~~ic'
while ~h~ period foe aqui:er r~stJr1~iJn
A longer pdriod of &ro~nd wat~r r~:uo!~ia~
a~::on to achieve lower aqui:~:- c:Jntar:t:.nanc lev~:s would in..:::'~~s~ ":,";-:5
and ma~ aE:~~t sc:ec:ion of ::,e al:~r~atives.
..~.
.
-'..~---
-------
,~-1,
~.O
CONCL:JS [ONS OF' G~omm ',.jA r::R ~S:~~!.-\L AC7:C~1
ALr::RNA7I'/'ES A,~AL'!C;:5
This sec~i~n provides reccrmm~nd~tions :ot" 6~~und wat~~ ,~e~:al ~c:~v~
at TCAA? based on the studi~s repot"t~d he~ein.
5e ~ec: ion tJ f a 6 ~~und
water remedial ac:ion al:er~ouitiv'! i3 J:sc',Jssed i:1 C~apc:~~ 3.1'),
~uc is
p~rticularly se:1s:cive to the regulatory
e~trac:e? water and the acc~pcaole
~:"i::-!~:.a
re~ardi~g c~eac~~~c:
t) e
, .
~ e'l e ~
o~ I:,und ~at~= qual~:y,
G:.l~=-
ance regarding t:,ese edceri,a have 1;:)ee:1 provided by ::?A, whi.;~ ::"~'..:orn-
mends that bac;qround levels bp. set as the t3=5:!~ Eor :~~at~ent and ,:!-
111.:!diui.(,)n oE ground wate~ quaLity, a:t:,ough a:1 al:er:1at:'I'! ::1nt~~::1at~on
level :nay ~e developed through a ccm?:.!~~ :~3si~i:i.t:r St:.ldy whi;:, i:1-
eludes risk a:1alysis and/or endanger~en: ass~ss~ent3 Ear r.!~~?cors and
pote:1tial rec:!?tor3,
7~e analyses p::"!senced ~e~~in consider~d t~e
EtJl~owing aquifer rest~ration and
~
g::Jund
:.:~:.t:~:-:.a:
'Jat.!:" t:e3C::1enC
.
.
1",-3 \. ""
Rescor,1t :on ,.,f ;he aqui::!:" t:.1.J .Iuman ~~H:oI
risk 1~ve13. or 27 ppo :or t~ic~~oroe~,ylene.
.
7r:!ac!11ent oE the ex:=ac:~d 6::.1und wacer to c:'P. ,
-) -~
10 levels Ear surfae~ ji.!Char6~ and :::.1 t:,e 10
"levels (::Jr 9t'.1dv pU:-P0ges anl:r) :~t' rei.:1j'!'..:::~n
into the g~ound water.
rne f~t~,wing conclusi.ons concer~lng 5:,und ~acer r~!11edLal
ar~ b ast!d on t:,e st ud ie s pr~::IeClted he ~; in.
ac:: ioCl
.
F.xtrac:ion oE g~ound wata: should inc~ude ~el13
in Units land 4 at the, s~uthwes:'1'CAA? ~ounciar:,
to int~rc!!pt contDinacad ~at;rs. '33se-i on t:,~
available hydrologic dat~, e:<::a<,:cLon wells
should be locat~rl ~n about 300-:00c spac:C1gs,
screened through :'!tost ~-f c;,e s~c:.lrated uni:s, and
provide an e~::ac:ion :oace at ::,e J..)undar:, 0":
about 500 6::m. These re~~mme!'1dac ions s:,ouid Je
refined 1;:)ased on tht! res~lts 0: ~ong-:a~ ?~ping
tests.
.
E:c:r3~civn of j:"o'.1nd wanr.3h\)u~j also b-e per-
Eot"::lei with-i.n C:,e inte~:or oE '!CAA?, at ar~.1S 0:
hi~h c~~ce!'1t:"at~
-------
"
\J
"
~
10 wells and sc~e~nerl at least through Unit 3.
.
The ground wat!!r !!xtractiort wells should be ooer-
at!d on a "chedul~ in which up~radi~rtt wetls ~r~
abandoned as contaminat i.on levels decrease, and
d\)wng~ad iertt pumping rates inc:"eased with t iml!
tJ opti~iz~ e~traction efficiency.
.
Sourc~ re:nedi.atloC\ i.i required t~ penult 'r~st~t'a-
tion 0: contaminat~d wat~rs on TCMP. The td-
c~loroe~~ylene ~ass loading to the ground water
E.om Si:~s D, G, and I ~ust be reduced si6niEi-
c3ntly compar~d t~ present esti~ated levels (ap-
proximat~ly 2 ord!!:"s of magnitl.1de) to achieve an
acceptable average conc~ntration at the TCAA?
boundary without ground water interception. The
t:p~ of sourc~ r~edi3tion ~ust b~ evaluated
r~lative to continued mass contributions to the
aqlJifer. 1: is pOS3io:~ that i:t-place closure ~r
in-place ~econtaminati.on may be appropriat~~
.
A pilot teHing program toJ evaluate ai: st:":?pi:'1~
and car~on adsor~tion t:eat~ent process~s Eor
cont aninat~d 6r'~.m4 wat ~r should be p~r:o nled .'
.
A combined air st~i?oini and car~on adsor?tion
?rocess with at least 9Q percent efEiciency
should ?rovide necessary treat~ent of the con-
taminat~d ground wate:". .1'his.ll!vel oE tr!!at:uent
. -)
-r5 e~pec:ed to e~ce~d the l~ human health
c:"iteria for trlchlorol!thyler'\e. Other major
volatile orianic compounds should also me~t t~is
criteria: however, t:~at:uent oE other constit-
uents., such as metals, have not been consider~d.
.
An air st:"ipping proc~ss with at least 99 perc~~t
efficiencv mav also achieve treatment o~ ground
. . -)
watar t~ che 10 hl.lltan heal:h crita~ia f.Jr
t~ichlor~ethylene. The pilot testing r~sul:5
should "e carefully eV3tuaced relacive t.:> r~cv31
efficienci~s for the desi~n volacile o~gan~c
~ompounds .
.
7~eat~~ e:=lueri't should b~ dis;;har~~d :0 per-:;Jta-
::.on po.nas ana utili::ed for TCA.,~? produc:i'.Jn S\.l-p-
?lies. The pond locatlIJn should be :'tear oJr at
S\)urc~s D and G to ac:e:er3ca :~d aquifar ~e~t~r-
adon pr..JgF3m. rhe sand and g:"3v~1 quarry a150
r~?rt~:s a pot!ntial ~ijc~ar~! llJcation EoI'
::=~.3ted eE:luent. The capaci:?' f.,r percolation
?cnd r~';har5~ :0 thl! ~:"'~lJnd '"at~:" ~ust 'Je :'..1r'::'~~
.
:_'"
.
"
-------
~-;
evaluat~d. al~hough l~ has ~e~~ ~scimac~d chac a
total pond r~char6~ :at~ ~E 7no g?m is possible.
Treate~-e::luent noc discharg~~ C~ ~he PQnd would
be availablo! for TCAA? use or .Jther uses (i.e.,
g~ound wat~~ reinjec:£on).
.
The g:"ound water e:,<::rac::i.,n, t':'!ac:Ttenc, and
e:flue~t dischar6~ syst~ms should ~e designe~ Co
acc~modac~ che ope~3tl~nal c~nsc:"aints C'~latlve
t~ lQc3cion ~~ sc:"~c:ures, and 3hould ~e ~apabte
0: mabcai~ing operatlons c:'\r'oug~out the loIi~ter
1'I10nc~s.
.
'The durat lr:Jn 0 f g~ound 'Jat~r r'!~ed ial ac: ion trJ
ac:"ie'le :-escoracilJn ~f :~e.aqui:er to c"nce~t:'a-
t£~n9 oE :=ichl~roet:"yt~ne ~ene:"al~y less :::".11'1 -
~7 ?PO is on ~he ~r~er "f :5 year3, ~ase~ ~n
available j.1t~ ~nd ignoring 50r?cion pr~cesses.
Available data in :he t::eratu:e 3uggeSCJ :~.1t
adsorption o~ :=ic:"loroe~hy~~ne ~n t:"e uni: 3
san~s woulci not ~e signi:icant.
Thes~ .;:onc~u.si~ns :~t":U c;,~ 'jasis for de.,elo!='De~c of a n!11edia~ ac:ion
.
plan.
Suppl~ent31 data gat:"er:ng eE:Jr:s are unde=~a:_by others, t:"e
results of which shouLd be revie~ed re~ative :~ the conclusi~ns of this
re;)orc. Addi..cionally, conErmaory cesting .::In parameters whic:" !Day hav"!
significant influence to che r~ed:al ac::ion plan sh.::luld be considered.
Sen5i.~i~::y ~lyses have shown thac the r~edi.al ac:ion alter~ativ~s
are viable for the anticipated ranges of chese ?ar3met~rs. Paramet~rs
which are 1'I105t signi~icant in :he analysi3 i~ctude hydraulic conduc-
tivity of Unic:s ') and ~ and l'I1ass IIJading rat~s associatl!~ with the
50 ur:: es .
..~.
.-
.
\
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TABLI:: 7-1
S~Y O. GROUND WATER TRF.A~F.NT F.FFICIENCy(l)
RF.QUBE:-!ENTS ::-OR VARIOUS' .GROUND WATER EXTRAC7ION
AND ~ONT1\OL SCF.NARIOS AND TREATED F.F';-LLTE~..
. DISCHARGE ALTF.~NA!I~S
TREATED EFFLL'Em' GROUND WATER EXTRACT!ON AND CONTROL SCFNA::\ !OS
DISCHARGE
ALT::RNA T!lI:: I H IV V VI
1. On- sic e dis<.;harg~ co Rice 99 99 en
Creek
2. Of:-site d isc hat'g~ to Q9(3) 9qO)
Minneapo 1 is se'Jer system
3. 0 f f- sit e discharge cv ~n ail
Lake for Shorev ie'J 99 99.
4. 0 ff- sic e discharge c.J Sc:. .
Paul Wacer S~ sc: em 99.9 99.9
5. On- 5 it e i.nfilcraci:Jn via
s pr ay irrigation or pe r-:: ~-
1 at ion po nd.s 99 99 99
~. On-~ite reinjec~ion t~
ground water 99.9 9Q.9 99. Q
7. Suppl ernent at or r;!?laceme:1t
prod uc t ion water for TCA.-\? 9q.9 99.9 99.9 99.9 99.9
(l) ff' . d .
E lCLency repor:e Ln perce:1t
(2),,_" indicates not applicable.
removal of c::"ichlor:;)ethyte~e (~i:'limum).
()
'Dependent on Metroool i~an ',.jaste Control Commission reoui.:':!TIe:'lts.
.......
.
,
\,
-------
I".F. 1-1
51ltlHARY OF' I:ROIINII WATF.M HHIE"IAI. Af:nm, AI:rI'ANATlVt:5
.
AI.n:RNAnVt:
HHIF.OIAI.
l\I:n ""
IIIIAA'I"IIIN
(y",iII ~ 1
1,0
f""""' .i.. I
~IIIINr:F. Hf.HF.IlIATlON
1:1111""" IIA'I""'.H
1~:Xnlllr:-r IV"{
I:II"'I"N"I,
In-"I.."" I"'"..nl_in''' i""
1
1,'>
1,,-1'1 no'" I:I..~..,,,
~f'I'''nr in I
n
III-Pia"" 0"':0"1 -inlll inn
~t'I'''IH in IV
I,
10
III-PI ac" 1:1",,",..
St','U,1r in IV
\
1\
'n-I'IH",' '"~':''nlltl.ill''' i..1t
St"'lint in VI
"
10
11,-1'1 a"" 1:1".11,,,
s. """,. in VI
2\ 111-1'1 n,:" Ot',:nnl ""' i lint inn ~",'..n,. in IV
" 10 I n-,'1.1"""" f:lt'~'" e S"""IIr in IV
9 1'i In-I'I.1O''' "'"t'unl In i" nl i .tlt s.'""",. in V
10 111 111-1'1 n,'" (~tU!f ""," S<:"II;I, ill V
'.
.
lHt:AHlt:N'r "I,n:HNArt n:!;
(t.Ft' II: II'N.:V )
, ,,( 11
Air 5' "I.,'Ing or
I:,..h i 11.,.1 IIi, e;I, i 1'1' i "I: nn,I
I:;lth.." A,I~''''I'I jllll (""7)
, ,,( 1)
IIIr e;I , IJ"""I! II'
.:""". i "",1 A i I :a r i ",. i,,~ nn.1
.:...1.,... A,I~..rl'l .Utl (.,.,t)
, ., 111
Air SI, 1J'f" "I: '"
':"1""''''"'' Air sl,'il.,.in~ ......1
1:,11 10.." 11.15...,.1 i.... ("'It)
. ., ("
A... e;lrll"""K II'
e:....'. i"",1 Air ~a., .,.,.i n~ 811,1
1:;1,1'"11 II,I~'"I'I i"" (I)"t)
. ., (n
A It SI, "," "'1( ,,~
1:....1. i "".1 II i I SI, i 1'1'; "I: .....1
1:.,,1..... A.I~...I" i.." ('I'It)
, " (I)
A., 51, '''I'' II,: ",
I:..,.Ioi ".,.1 Ai, SI, I",. i "11 "'hl
1:.11 I..." A,h.., 1'1 illn ('1'11)
I:..." i "...1 Ai, e;I, i "I.i "II IIn.'
17... I"." 11.1 ~.., 1'1 i.." (')'1.91 J
I:..." i "..,I Ai, SI, i 1'1' i "II a....
I:,,, 10.." A,h.....' i.." (q", 9% )
I:....." i "".1 II i ~ SI, i ';r i "II n...'
.:,,, 1"," 11.1 ~'" "I i.." (".,. ')7 )
"".." i 11",1 Ai, SI, i 1'1' i "p. """
I:"",.." A.I '''..'1 i.." ("'1. 'I!)
0f.51':N
(;AI'I\I: ITV
("1"')
1.0011
I ,01111
I. ""0
1.""0
1,111111
1.11110
1,\00
I. \00
'. "iOn
'."ino
n'''I.lff.NT Ol5r.vnr.£
III.HHII"l'1 Vf. .
501,,,1 "",I I:, ave' pi t
5.."., .",1 r.,..v..1 pit
I',',cola' ioo Pond.
II,'''' 5il". I' 11.,,1 r.
"t!f"cnla' inn Pnn,t.
""01' Si,,,. .. "",I r.
..
p,',c..1 a' in" 1'..'.,,1.
II" a, S i , ". II .",1 ,;
I',',colll' ion Po",'.
II" II' 5 i I". 0 11,,,1 ,;
Pp,cola' i..n 1'0.,,1.
"".Ir Sil". II "",. i:
r.'re,,1 '" i..n pp".I.
""", 51 I ". 0 a",1 r.
."j".:t ion
, .
lie' 'If
. ..
I"j..ction We I'.
II )""...",,1 ..."1 .., .'.1 r ,..'1 """/".""1 ,..1
-.. t,.....,i!'j'fI .tf "J(I...n.",i"l1 Vt"1!'& 1''''olt,'.1 .1' "", reA"" Hn..t"""!'al I'nullilltry An,'/..r
""." I h.. ""'I""'" i1t 1'11" .
(2)1:""...", ,Ii.d,.Hr." .1'1"".,11 iv.,. ,1'~...., ,Ionl
.\li" I... ."1'1" i",1 hv ,Ito, 1"',11,..,,,1. "V.I."...
t'ur,.'ul 'n:"",' "1 '''''M'' i.... 1I!1:11~" i~ Rnn,nUn ,!:III..n!ll 'h'_r ''''Y :III.,
(11 . " ,
Air ~'rll"I)lnR ,"ilV I,.. ",u'!III,'.o."...1
,..:hi..v.!" tI..... inK ,d 1..1 "!!III iUft.
Inr ,I". t r'! nl 111""(
""'tt.,.~.. ,1","'",lin~ nn
'-"'''ttY~' t f'" it.' i.,,,,. i..!t
-------
TABLE 7-3
~ET PR~SENT WOR~ St~~R~
OF r.ROVND WAT::R ~~En!AL ACTIn~ ALTF:R:-JA711/::S
COMB!NED Al~ .STRIPpr~G ~~D CARSON A~SORPTIO~
RE~~!)!A!ION SOURCE PVXPING TREA~~T DrSr.HARGE TOTAL NF:T
ALTERNATIVE P::RIOD ~~:'\I::D LA '!!nN SCHE~F. COS7S <:05T5 PRC:S::S!'
(y~ars) (51000' s). (51000' s) (51001')' s) (5Ln00' s) WO~7H
(S~0f)0's)
40 5,()6~(1) 3,505(3) 1,9~1(7) l~7(9) 1n,i21ClL)
2 45 2 ,806 ( 2) 3,505(3) 1,Q61(i) 1~7(0) q ,_:)(11)
'. ,..) ,
3 25 5.068(1) 4,581')(4) 2,269(7) 100(9) 12.107
2,3n6(2) 4 696 (!oJ 2,324 (i) (0)
4 30 , 187" 10,n13
5 25 5,068(1) 4,062(5) 2,7i3(j) 190(9) 1: ,093
6 30 :,R06(2) 4,175(5) 2 ,841 ( i) 18i(0) 10,009
7 2S :; ,068 (1) I -80(4) 2,.~34(3) 190(9) 12,6i:
-.,)
2.806c:n 4,606(4) 2,RO)(") (0)' .
8 30 187' I0,S8:-
9 2S 5,063(1) 2,975(6) 3,008(B) 83(10) 11 .034
10 30 2,806(2). 2,Q39(6) 3,073(3) 83(10) 8 ,on ~
\;
(1)
!n-?lace decon~amina~ion.
( 2 )
!n-place closure.
(3) . 11' h
. 13 lnterceptor we s~ts Wlt a. capacity of 70 gem/set.
(4) ( . ) d
!ntarce?tor lnt; an extraction (ext.) wells
0-10 years 13 into @ 40 gpm and 10 ext. @ 7n~?m
10-20 years 11 into @ ~5 gpm and S ext. @ 100 ~?m
20+ years 2 into @ 75 gpm and 7 ext. ~ 150 gpm.
(5)13 interceptor well sets with a ca!'acity of 140 g~/set.
(6)10 extraction wells ~ 1~0 gpm with 13 injec~ion wells at 7n gem.
(7) f-"
99 percen~ treatment e.:1Clency.
(8)' ... . .
99.Q percent tr~at~en:.er~lclency.
. (9) '.. . .
percolatlon pona ~ons:ruc:~on and reclamatlon.
(10) f.'. . .:..
Cost 0 malntalnlng a pressurlzed lnjectlon system.
(11) .. . .
Net present worth f::>r life first 3n years of t!'~3t:uent.
~
(;'
.
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..
.'
TARLE 7-'"
NET PR~SENT WORTH 5~~AR~
-OF GROL~D wATF.~ RE~F.D!AL AC7:CN ALTF.~NA!IV~S
A!~ STR!PP!~G
i
R~EIHA1':ON SOURCE p l~P LNG TRF.A ~ ~'T DrSCiJ_~RGF. TOT.~~ 'I:::""':'
AL TERNATI VE PER!OD RE~!) 1.-\ T :ON Sr.HE~E COS~S COSTS ~,::SF.:'7 ~
(yea:,s) ( S l 000' s) ( 5 1 ('11")(')' s) (5100n's) (510no's) ''';O:C~
( S >l () r ' s )
J:. ",0 5,068(:) 3,505(3) t,41:(7) 187(8) 10,L7:(0)
2 £.5 2 ,3(') 6 ( 2) 3,~()5C3) 1,411(7) 1~7(~) ( ~ \
7 011') )
, .
5,(,)680) (, ) 1 1 01 (j) 19n(R)
3 25 4 , 5 RO .. ,......~ l ~ , 33:
2,~06(2) (" 1.404(;) 187(~)
4 30 4 -:'06 ..' 9, t 83
,
5.06.'1(1) (- I 1,551 (7) 190(8)
5 2C; -' n Ii" ') tll,Sit
w. , , '-
(... ) (- \ 1 C;~~(7) 1M(8)
6 31'1 2 . R() 6 .;.. '1':' 5 ). 8,719
... ' , ~-
.
(1)
IC\-place decontaminat:ion.
(.., )
- In- pl ac e closure.
())13 interceptor welt sets wi~h a capacity of 71 ~pm/se~.
(4)Interceptor (int'.) aC\d extraction (ext ,) ~el:s
0-10 years 13' int. ~ 4(\ g?m and 10 ext.,~ iO g?lt\ --...
10-2f) years 11 int,. @ 65 g;xn and 5 ext. @ ton gpm
20+ years 2 into @ 75 gpm and 7 ext. ~ 150 gpm.
(5)13 i.nterceptor well sets ~ith a capaci.ty of l~i! gpm/se~.
(6)10 extraction ~ells @ 140 gpm ~ith 13 i.:1;ec:~on ~etts at 7n g?t!1. .
(1) 0 F-' .
Q, percent t~eatment e.=lclency.
(8 ) 1.. .
Per.:o atlon pona constructlon and reclamat~o~,
(9 )
Net present worth for the first 30 ye3!'s of t:,~atment.
..~.
.-
.
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