United States
Environmental Protection
Agency
Office of.
Emergency end
Remedial Response
EPA:ROD.R08.84 001
April 1984
~EPA
Superfund
Record of Decision:
~f
fB & S -2.../ '-1070
C~Uectio~~
Jrce Center I
I
~
19107
Milltown Site, MT
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing;
,. REPORT NO. 12. 3. RECIPIENT'S ACCESSION NO.
EPA/ROD/R08-84/001
4. TITLE AND SUBTITLE 6', REPORT DATE
SUPERFUND RECORD OF DECISION: 4/14/84
. Milltown Site, MT 6. PERFORMING ORGANIZATION CODE
7. AUTHORIS) 8. PERFORMING ORGANIZATION REPORT NO.
19. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT NO.
". CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS 13. TYPE OF REPORT AND PERIOD COVERED
U.S. Environmental Protection Agency Final ROD ReDort
401 M Street, S.W. 14. SPONSORING AGENCY CODE
Washington, D.C. 20460
800/00
15. SUPPLEMENTARY NOTES
16. ABSTRACT
The Milltown Reservoir Sediments site is located in Missoula County, Montana.
The site is adjacent to the Milltown Darn where the Big Blackfoot River joins the Clark
Fork River. Constructed in 1906, this hydroelectric darn formed a reservoir that
trapped sediments from mining, milling, and smelting operations in the upper Clark
Fork Valley. During the years since construction, the reservoir storaCTe has been
almost totally filled with arsenic contaminated sediments. I,' : .. . ".;1wn' s
four community water supply wells were found to be contarni~~ ether
heavy metals. The highest arsenic levels measured have beer; .." ..., to 0.90
milligrams per liter (mg/l).
The selected remedial alternative consists of: construction of a new well from
a hydraulically separate aquifer; construction of a new distribution system; flushing
the plumbing system of each house to remove suspended materials from the water system
and plumbing and testing the water quality in each house to assure that the arsenic
standard has been met. The capital cost for the selected alternative is estimated
to be $262,714 and annual O&M costs are $4,238.
Key Words: Alternate Water Supply, Community Services Enhancement, Fire Protec-
tion, Shared Cost, Arsenic, Drinking Water Standards, Internal
Plumbing, Mining Wastes, Supplemental ROD, Water Quality
17. KEY WORDS AND DOCUMENT ANALYSIS
a. DESCRIPTORS b.IDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
Record of Decision:
Milltown Reservoir Sediments, MT
Contaminated media: gw, soil
Key contaminants: metals, arsenic
/ \
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ROD ISSUES ABSTRACT
Site:
Milltown Reservoir Sediments, Montana
Region:
VIII
AA, OSWER
Briefing Date:
March 21, 1984
SITE DESCRIPTION
The Milltown Reservoir Sediments site is located in Missoula
County, Montana. The site is adjacent to the Milltown Dam where the
Big Blackfoot River joins the Clark Fork River. Constructed in 1906,
this hydroelectric dam formed a reservoir that trapped sediments from
mining, milling, and smelting operations in the upper Clark Fork
Valley. During the years since construction, the reservoir storage has
been almost totally filled with arsenic contaminated se~~~0~tS. In
May, 1981, Milltown's four community water supply wells ",-,'2 found to
be contaminated with arsenic and other heavy metals. The highest
arsenic levels measured have been between 0.54 to 0.90 milligrams per
liter (mg/l).
SELECTED ALTERNATIVE
The selected remedial alternative consists of: construction of
~ew well from a hydraulically separate aquifer; construction of a n~
distribution system; flushing the plumbing system of eac~ house to
remove suspended mater ials from the water syster: ~.. : ~ _:' : i.,.q and
testing the water quality in each house to aSSUl '.- :...,'" t. t.ne arsenic
standard has been met. The capital cost for the selected alternative
is estimated to be $262,714 and annual O&M costs are $4,238.
ISSUES AND RESOLUTIONS
KEY WORDS
1.
The affected community requested EPA to deve-
lop a new water supply system with increased
capacity to accommodate fire protection de-
mands in addition to normal domestic uses.
EPA considered the proposal but decided that
the increased cost of fire protection was
beyond the scope to remedy a contaminated
water supply. The reason for this decision
was that there was no previously existing
fire protection system. It was recommended
. Alternate Water
Supply
. Community Services
Enhancement
. Fire Protection
. Shared Cost
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Milltown Reservoir Sediments, Montana
March 21, 1984
Continued
ISSUES AND RESOLUTIONS
that the community solicit bids for a com-
bined domestic supply/fire protection sys-
tem. With this information, the community
could decide if they wanted to have the fire
protection capacity installed at their own
expense.
2.
The EPA agreed to develop a new water sup-
ply for a community with arsenic concen-
trations exceeding the EPA's drinking water
standard (0.050 mg/l). The new system was
planned to connect with the existing plumb-
ing at each residence. The community re-
quested that the internal plumbing of exist-
ing houses be replaced as well. This
request was made because of their concern
with the possibility of residual arsenic,
in the plumbing and the hot water tank,
becoming mobile and contaminating the new
supply. The possibility of residual arsenic
contaminating the new supply after flushing
was remote.
In the unlikely event the water supply in
.. individual homes did not meet the arsenic
drinking water standard after extended
flushing, a supplemental ROD would be
prepared to consider minimal measures to
provide safe drinking water.
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KEY WORDS
. Arsenic
. Drinking Water
Standards
. Internal Plumbing
. Mining Wastes
. Supplemental ROD
. WatF- ~~~lity
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RECORD OF DECISION
REMEDIAL ALTERNATIVE SELECTION
REPLACEMENT POTABLE WATER SUPPLY
Site:
Milltown Reservoir Sediments, Milltown, Montana
Analysis Reviewed:
I have reviewed the following documents describing the
analysis of cost-effectiveness of alternatives for a replacement
water supply at the Milltown site.
- Milltown Water Supply and Distribution System Study
Robert A. Peccia and Associates, December 1983.
- Fire Protection System - Milltown Study
Robert A. Peccia and Associates, February 1984.
- Staff summaries and recommendations; and
- Recommendation by the Montana Department of Health and
Environmental Sciences (MDHES).
Description of Selected Option:
- Abandonment of existing Milltown ground water supply and
distribution system that has been affected by leaching of
heavy metals from reservoir sediments.
- Replacement and relocation of Milltown Wa'
Association water supply and transmissior.
with a capacity of 0.29 MGD.
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Declarations:
Consistent with the Comprehe~sive Environmental Response,
Compensation and Liability Act of 1980 (CERCLA), and the National
Contingency Plan, I have determined that an alternative water
supply for the Milltown Reservoir Sediments site is a cost-
effective remedy, and that it is a key action which is necessary
to effectively mitigate and minimize damage to public health,
welfare and the environment. I have determined that this action
is appropriate when balanced against the need to use Trust Fund
money at other sites. Should individual houses not meet the
arsenic standard after flushing and testing, a Supplemental
Record of Decision may be considered.
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A Supplemental Record of Decision will be submitted for
consideration upon the completion of the State of Montana's
technical analysis and evaluation of source control remedial
act ions.
4~
~\\.~-.?
Lee M. Thomas
Assistant Administrator
Office of Solid Waste and Emergency
Response
f/;'-i-JS-'I
I I, V
Date
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REMEDIAL ALTERNATIVE SELECTION
MILLTOWN RESERVOIR SEDIMENTS SITE
MILL TOWN, MONTANA
HISTORY
The Milltown Reservoir Sediments site is located in Missoula
County, Montana. The site is adjacent to the Milltown Dam where
the Big Blackfoot River joins the Clark Fork River. Constructed
in 1906, this hydroelectric dam formed a reservoir that trapped
sediments from mining, milling, and smelting operations in the
upper Clark Fork Valley. During the years since construction,
the reservoir storage has been almost totally filled with these
sediments.
In May 1981, Milltown's four community water supply wells
located between Interstate 90 and the Burlington Northern railway
tracks were found by local health officials to be contaminated
with arsenic and other heavy metals. The highest arsenic levels
measured have been between 0.54 to 0.90 milligrams per liter
(mg/l), up to 20 times the maximum contaminant level established
by EPA in the National Interim primary Drinking Water Regulations.
Ingestion of arsenic in sufficient quantities can lead to
abdominal pain, vomiting; coma or death.
Residents were advised by State health officials on August 20,
1981, not to use waters from the affected wells for potable
purposes. Initially, the thirty-three residences supplied from
these wells were without a temporary wate.r supply i the affected
populace obtained water from neighbors or business~~ wi~~ ~~con-
taminated wells. During the summer of 1983, voL' .','::S ":.:. .:1g
National Guard equipment began supplying reside~t~ with p~~@ble
water from a. tank truck, driven door-to-door bi-weekly. No source
of bottled water exists in the area.
In July 1983, the remedial investigation (RI) was formally
begun through a Cooperative Agreement with Montana Department
of Health and Environmental Services (MDHES). An initial task
of the RI was to determine the source and extent of contamination
to' the existing drinking water supply. In December 1983, the
consultant identified the sediments as the cause of ground water
contamination as well as identifying the present distribution
and likely future disposition of the contaminants in the water
supply. A focused feasibility study (FS) was begun in October
1983 which examined alternative water supplies to Mi1ltown. The
feasibility study recommended a replacement ground water system
and extending an existing fire protection system into the affected
area.
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COMMUNITY RELATIONS
On December 20, 1983 and January 4, 1984, at public meetings
held in Missoula and Bonner, Montana, the findings and recommen-
dations of the focused feasibility study were presented. The
community urged the expeditious implementation of the selected
alternative.
Comment
All comments received supported the selected alternative and
stres~ed the need for inclusion of fire protection in the -final
design and construction.
Respons e
See discussion below on fire protection.
Comment
Since the public meeting some residents have requested that
their pipes within their homes be replaced. There is concern that
the pipes are contaminated with arsenic.
Response
As necessary, the water system will pe flushed and tested.
If water within the house does not meet the arsenic "..:"". ,,", a
Supplemental Record of Decision may be prepared t:- ' . ::'';
to consider various options to provide safe drin:.- ',':; , The
State and EPA expect that after flushing each house wlll meet the
arsenic standard and no further action will be required.
ENFORCEMENT
In December 1983, the remedial investigation contractor
conclusively identified the Milltown Reservoir sediments as the
cause of the contaminated drinking water in Milltown, Montana.
These sediments have been historically deposited over the last
78 years, since the construction of Milltown Dam. Metal mining,
milling, and smelting discharges upstream have undoubtedly con-
tributed heavy metals to this sediment buildup. EPA Region VIII
determined ownership of mining activities upstream of Milltown.
This effort identified 18 separate areas where ownership records
showed historical activity that could have contributed discharges
to Clark Fork drainage. No further efforts have been undertaken
attempting to substantiate this information.
There have been no previous State or Federal enforcement
actions regarding this site.
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CURRENT STATUS
The contaminated reservoir sediments continue to pollute
Milltown's wells. Remedial investigation testing indicates this
contamination appears to be hydraulically confined to the
presently contaminated area. Lower aquifers do not appear to be
contaminated. Ongoing monitoring will determine the extent and
direction of the plume.
ALTERNATIVES SCREENING
The feasibility study initially considered fi~e alternati~es
(see Table 1). Implementation of anyone of the fi~e alternati~es
would result in a potable water system that would pro~ide residents
with uncontaminated water. The alternati~es were screened on the
basis of technical feasibility and costs of implementation. No
alternative was considered that would have involved ingestion of
untreated water from the Milltown reservoir, due to health hazards.
The no action alternative would continue to provide bottled
water as a long term remedy. There is no local source of bottled
water available. Bottled water is currently being supplied by
the National Guard and is a very inconvenient and insufficient
supply for bathing. Because of the public health and welfare
considerations, this option is rejected. The remaining alternatives
were all judgedeffecti~e in protecting health, welfare, and the
environment. Alternative 1 was to connect the area to the
municipal supply of the City of Missoula; The cost of this
action is over twice the capital and twice the O&M costs: - ~ne
recommended alternative and was therefore rejected. Al~e~nati~e
2 was to provide a new surface water treatment plant to the
area. The costs of this action are over twice the capital costs
and five times the O&M costs and was therefore rejected. Alternative
3 would treat the source of contamination at each existing well
head with a small treatment facility. The capital costs were
twice that of the recommended alternative and five times the
cost for O&M and was therefore rejected. Alternative 5 was to
buy-out the community and relocate the residents. This alternative
was not only costly (3 times the capital costs of the recommended
alternative) but disruptive to the community and not necessary.
This alternative was therefore rejected.
Should houses not meet the arsenic standard after flushing,
further remedial measures would be studied and may be recommended.
At this time there is insufficient information to determine how
many houses would be affected and the extent of action required.
(The State and EPA do not expect any of the houses to fail the
arsenic standard but this cannot be guaranteed in advance.)
Even if substantial remedial work is required to provide taps or
replace plumbing, Alternative 4 is clearly cost effective when
compared to buy-out of the community (Alternative 5). Alternative
4 costs $270,751 compared to $829,000 for Alternative 5.
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Alternative 4 was found to be the least expensive alternative
to alleviate the threat to public health and welfare. Alternative
4 involves construction of a new well and appurtenances, con-
struction of a new distribution system, and connection of this
distribution system to individual residences. This alternative
is considered the most cost-effective. Total capital and long-
term operation costs are summarized in Table 1.
Locations of existing distribution piping are unknown as
these lines were never mapped and records were not kept of changes
in the systems. The various systems apparently have been in use
more than 30 years, with maintenance performed on an as needed
basis. The existing water systems are undersized. Consequently,
tie-ins to the existing distribution systems are not feasible.
In addition to providing a safe, potable supoly of water,
providing fire protection was also evaluated. Two options were
considered. First, a separate fire protection line connected to
Champion's existing fire protection system was examlr.;,',; . -'-'.\:-':')
4A). The incremental cost of this system is estirn~~.
$76,950. The second fire protection system examir.-'- . ~;"'~...on 48)
was to upgrade Alternative 4. A new pump, and la~;e= pipes,
valves and pump house would be required. In addition elevated
storage would also be needed for adequate water pressure and
storage. This system would cost at least $.130,000. Therefore,
connection to the Champion fire protection system is the recom-
mended option of the State.
...The existing distribution system at Milltown is inadequate
to provide fire protection, and the community currently has no
fire protection system. Providing a fire protection system in
these circumstances would be unrelated to th~ health and
environmental hazard for which CERCLA funds are being committed.
Therefore, the funds for a separate or combined fire protection
system are not included in the final alternative.
RECOMMENDED WATER SUPPLY
The alternative recommended, 4, consists of an 8-inch
diameter, ISO-foot deep well, pump, well house, piping, appur-
tenances and controls. The well would be installed adjacent to
the Champion C-2 well, which currently supplies potable water to
a portion of Milltown residences unaffected by current contam-
ination. This area has been shown through remedial investigation
testing to be hydraulically separate from the aquifer affected.
by sediment leaching, providing water of excellent quality and
adequate yield for consumption. Total system capacity, as
designed, is 0.29 MGD. During design there will be a final
determination of the sizing for the pump, well and appurtenances.
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This water supply well is to be connected to a dist~ibution
system consisting of 6-inch diameter PVC trunk line and 4-inch
PVC mains with 3/4-inch service connections to each residence.
The plumbing system of each house will be flushed to remove
suspended materials from the water system and plumbing. The
houses will be tested to assu~e that the arsenic standard is met.
Faucets should be opened a sufficient pe~iod of time p~ior to
sampling to ensure that water is being drawn from the distribution
system in the streets.
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TABLE 1
Comparison of Milltown Water Supply Alternatives
Capital Cost*
O&M Cost/yr
Comment
Alternative 0:
No Action/Bottled Water
o
Ineffective, no
long-term remedy
Alternative 1:
Connection with
Missoula System
$572,940
$8,582
Effecti.ve but
high cost
Alternative. 2:
New Surface Water
Treatment Plant
591,300
21,780
Effective but
high cost
i\lternative 3:
Treatment of
Existing Wells
to Remove Arsenic
Effective but
high cost
555,525
22,770
ernative 4:
New Well and
Distribution
System
270,751
4,238
Good quality water
'. :,east
. <.: "ac t ion II
..~rnative
Alternative 5:
Buy-out
of Commu ni ty
828,736
5,582
Relocation is dis-
ruptive and expen-
sive; does not
appear neccessary
FIRE PROTECTION ALTERNATIVES
A
Tie into the Champion
Fire Protection System
$ 76,950
High degree of
"reliability
B
upgrade Alternative 4
to Provide Adequate
Fire Protection
129,950
Less reliable
service. Higher
cost
*
Includes 10% contingency and 20% engineering design and
5% administration.
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Costs of the alternative selected are as follows:
Alternative 4
DESIGN AND CONSTRUCTION
CAPITAL COSTS
Well and Appurtenances
Domestic Water Distribution System
Subtotal
$ 76,930
92,290
$169,220
Design
Administrative
Contingency @20%
Subtotal
34,656
30,036
36,839
$270,751
Operation and Maintenance*--for one year
Total
4,238
$274,989
*Operation and maintenance expenses on the pump and other
mechanical equipment are to be provided by the Milltown
Water Users Association after the project is accepted by
. MDHES. An agreement will be signed by the Association and
the Montana Department of Health and Environmental Sciences
to assume the responsibility.
The State of Montana is prepared to assume 10 percen~ of the
costs of design and construction of this preferred alternatlve.
CERCLA funds would be used to finance 90 percent of these costs.
Under the existing Cooperative Agreement, the State of Montana is
completing the remedial investigation related to contaminant source
characterization. A contract for a source control feasibility
study is to be awarded in the near future. A supplemental Record
of Decision will be prepared upon completion of the source control
feasibility study.
RECOMMENDATION
Staff recommends approval of the final design and construction
of a potable drinking water system as described above. The
approved systems should be constructed to the size and capacity
indicated in the focused feasibility study.
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Q
NEXT STEPS
7
Milest ones
Sign ROD
Amend CA for Design & Construction
Complete Design
Award Construction Contract
Complete Construction
Complete Long-term RI
Complete Long-term FS
Date
March 1984
March 1984
May 1984
July 1984
October 1984
December 1984
July 1985
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