DATE
SUBJECT;
FROM
TO
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
JUN 1 1984
DECISION MEMORANDUM - Initial Remedial Measure for Ponder^Corner Site,
Lakewood, Washington
Charles E. Findley, Acting Directo,
Air & Waste Management Division
Ernesta B. Barnes
Regional Administrator
PURPOSE
This memorandum is to request authorization to undertake an Initial
Remedial Measure (IRM) of a water treatment system at the Ponders Corner
site in Lakewood, Washington. A Record of Decision documenting EPA's
decision process is attached for your signature. The State of Washington
has agreed that EPA will take the lead on the design/construction phase of
this project. Two copies of Superfund State Contract providing the
mechanism for obtaining the State cost share and assurances and
documenting EPA and State responsibilities are also attached for your
signature. The approved Region 10 Remedial Accomplishments Plan allocates
$600,000 for this project.
BACKGROUND
Ponders Corner (also called Lakewood) is on the National Priorities List.
In 1981 two major drinking water production wells of the Lakewood Water
District, Wells H-l and H-2, were found to be contaminated by
significantly high levels of the chlorinated solvents trichloroethylene,
1,2-(trans)dichloroethylene and tetrachloroethylene.. The wells supplied
over 10 percent of the District's needs. The Water District immediately
took the wells out of production, notified the customers of the
contamination and requested that a water conservation plan be followed.
Subsequent groundwater and soil sampling determined that the septic tanks
and the ground disposal area of Plaza Cleaners, a commercial dry cleaning,
establishment located approximately 800 feet north of the wells and across
1-5, were the probable sources of the contamination. Plaza Cleaners has
since stopped disposal of the solvents to the ground and the septic tanks,
and surrounding soils have been dug out and replaced with noncontaminated
soil. It is believed that these actions have stopped the discharge of
contaminating solvents into the ground and that residual solvents in the
soil and the underlying aquifer constitute the source that is presently
contaminating Wells H-l and H-2. Groundwater movement dictates the spread
of the contaminants when the wells are not operating. This movement has
not been fully characterized but is known to flow generally in a northwest
direction.
EPA Form 1320-« (Rev. 3-76)
-------
OBJECTIVE
A major objective of the IRM is to:
1. Restrict the spread of contamination in the aquifer to reduce
the threat of contamination to other wells and to reduce
ultimate cleanup requirements. This is consistent with section
300.68(e)(1)(iii) of the National Oil and Hazardous Substances
Contingency Plan (NCP) to limit exposure or threat of exposure
to a significant health or environmental hazard.
In addition, the water treatment system will:
2. Restore normal water service to this area including restoration
of normal fire-fighting capability.
3. Provide the required facilities in the shortest practical time,
preferably to meet the 1984 summer peak demand.
PROPOSED PROJECT
The proposed IRM will consist of two air stripping towers similar to the
towers built at Well 12-A in Tacoma. A number of alternatives were
analyzed in the Focused Feasibility Study. The only two alternatives that
met the established objectives of the project, including health criteria
established by the Tacoma-Pierce County Health Department, were a carbon
adsorption treatment system and the air stripping towers. On the basis of
cost, as indicated below, the air stripping system is recommended.
Air
Carbon Stripping
(Thou. $) (Thou. $)
Construction Cost 1,419 540
Annual O&M 289 82
First Year Total 1,708 622
3-Year Present Worth 1,701 572
15-Year Present Worth 3,717 1,163
EPA will pay 90 percent of the construction costs and the first year's
operation and maintenance (O&M) of the treatment system. The State will
pay the other 10 percent of the construction costs. The Lakewood Water
District has agreed to pay the normal cost of operating the wells and will
work out an agreement with the State for the O&M costs. The Water
District is also working on a plan to increase their rates to cover O&M.
-------
This project will not duplicate any previous work at this site and it will
be coordinated with the full scale remedial investigation and feasibility
study EPA is initiating on the site during FY 84. It is possible that the
system will become part of the final remedial action, although this will
be determined during the investigation and feasibility study.
ENFORCEMENT
The State of Washington Department of Ecology issued an administrative
order to the dry cleaning establishment in early summer 1983 to assess the
problem and clean-up the source. The former and current owners of the
cleaners subsequently signed a stipulated agreement with WDOE before the
State Pollution Control Hearings Board. As a result of the Order and
Agreement, Plaza Cleaners stopped disposal of solvents to the ground and
septic tanks, removed much of the contaminated surface soil and replaced
it with uncontaminated soil and closed the commercial laundry operation.
The contaminated soil was removed to the Plaza Cleaners parking lot and
covered. It is believed that these actions stopped the continuing
discharge of contaminating solvents into the ground and that residual
solvents in the soil and the underlying aquifer constitute the source that
is presently contaminating Wells H-l and H-2.
In addition, EPA sent combination notice/104(e) letters to the current and
former owners of Plaza Cleaners in September 1983. EPA may at a later
date decide to recover project costs. The Office of Regional Counsel
concurs with the proposed project.
COMMUNITY RELATIONS
The primary objectives of the community relations activities for the site
are: (1) to provide citizens, involved agencies and organizations,
elected officials and the media with accurate, timely information about
the proposed IRM and the larger scale investigation and feasibility study;
and (2) to provide the means for interested parties to express concerns
and make inquiries to ensure effective two-way communication. A two-week
public comment period and a public meeting were held on the Focused
Feasibility Study in May, 1984. Most comments received were in favor of
the project. A community relations responsiveness summary is also
attached to this memorandum and will be distributed to all those on the
mailing list. The community relations effort will continue throughout the
construction of the project and during the investigation and feasibility
study.
-------
/
4.
RECOMMENDATIONS
This request has been coordinated with the appropriate Regional and
Headquarters Offices and the State of Washington. I recommend that,
consistent with the Comprehensive Environmental Response, Compensation,
and Liability Act of 1980 (CERCLA), and the National Contingency Plan (40
CFR Part 300), you determine that the proposed water treatment system at
Ponders Corner is a feasible and cost-effective initial remedial action
necessary to protect public health and the environment. The action being
taken is also appropriate when balanced against the resources available in
the Trust Fund and the need to respond to other sites.
Attachment
-------
RECORD OF DECISION
INITIAL REMEDIAL MEASURE ALTERNATIVE SELECTION
SITE: Ponders Corner, Washington
DOCUMENTS REVIEWED:
I have reviewed the following documents describing the analysis of
cost-effectiveness of Initial Remedial Measure alternatives for the
Ponders Corner Site:
""Focused Feasibility Study: Ponders Corner Well Water Treatment
Facility, Lakewood, Washington," May 1984.
°The attached "Summary of Remedial Alternative Selection, Ponders
Corner, Washington," May 1984.
"Community Relations Responsiveness Summary.
"Staff summaries and recommendations.
DECLARATIONS:
Consistent with the Comprehensive Environmental Response, Compensation,
and Liability Act of 1980, and the National Oil and Hazardous Substances
Contingency Plan, I have determined that the construction of air stripping
towers at Lakewood Wells H-l and H-2 effectively mitigates and minimizes
damage to, and provides adequate protection of public health, welfare, and
the environment. I have also determined that the action being taken is
appropriate when balanced against the need to use Trust Fund money at
other sites. In addition, I have determined that the construction of air
stripping towers is more cost-effective than other remedial actions and is
necessary to protect public health and welfare and the environment from a
potential risk which may be created by a continued shut-down of Wells H-l
and H-2 and, therefore, consistent with Section 101(24) of CERCLA.
ERNESTA B. BARNES
REGIONAL ADMINISTRATOR
JUN 1 1984
-------
J. Future Actions
An obligation of Fund monies has been made to complete a full RI/FS
beginning summer 1984. A scope of work has been approved and CH2M Hill
will begin working on the work plan by June. The remedial investigation
will likely include the construction of several additional monitoring
wells to determine if any other sources of contamination exist in the
area, and to find out how far the contaminant plume now extends. Since
Wells H-l and H-2 have been shut down, it is believed the contamination
has been flowing in a different direction. This information is important
in designing a final remedial action for the well contamination problem.
In addition, more work is proposed for the Plaza Cleaners site to
determine if it is a continuing source of contamination. Specifically,
soil samples will be taken and an investigation of the septic tank
drainfield is planned. The drainfield, and suspected well at the end of
it, have never been found. The soil in the area of the drainfield and
well may remain contaminated, even though no solvents now enter the septic
tanks.
Following that investigation, a feasibility study will be prepared,
assessing various options for remedying the situation. The same process
outlined in this Record of Decision will likely be used to select the
alternative to be implemented. Negotiations with responsible parties on
implementing the remedial action may take place at that time.
-------
SUMMARY OF REMEDIAL ALTERNATIVE SELECTION
PONDERS CORNER, WASHINGTON
A. Site Location and Description
Lakewood Water District's Production Wells H-l and H-2 are located in the
Ponders Corner neighborhood of Lakewood in Pierce County, Washington, just
north and west of McChord Air Force Base and southeast of Interstate 5, as
shown in Figures 1 and 2. Lakewood is a predominantly commercial and
residential area located south of the City of Tacoma.
Wells H-l and H-2 make up the Ponders Cornerwell field. Both wells are
approximately 110 feet deep, and together they can supply up to 2,800
gallons per minute (gpm). Before the wells were taken out of production
because of contamination, they supplied water to the Ponders/Nyanza Park
area and provided over 10 percent of the District's needs.
B. Site History
In July 1981, EPA sampled drinking water wells in the Tacoma, Washington,
area for contamination by purgeabl e halocarbons. The sampling showed that
Lakewood Wells H-l and H-2 were contaminated with 1,2-
(trans)dichl oroethylene, tri chl oroethylene, and tetrachl oroethylene. In
mid-August 1981, Lakewood Water District took Wells H-l and H-2 out of
production, notified its customers of the well contamination, and
requested that a water conservation plan be followed.
A subsequent inspection and sampling effort by EPA and the Washington
Department of Ecology (WDOE) determined that the septic tanks and the
ground disposal areas of a commercial establishment known as Plaza
Cleaners were the probable sources of well water contamination. Plaza
Cleaners is located several hundered feet north of the wells and across
Interstate 1-5.
In the past, Plaza Cleaners operated a dry cleaning and laundry business
with dry cleaning machines, reclaimers (dryers), and commercial washing
machines. Plaza Cleaners processed approximately 6,000 pounds of dry
cleaning and 2,000 pounds of laundry per week. Some solvents used in the
dry cleaning process were disposed of in the Cleaner's 4,250-gallon septic
tank system and were flushed through by approximately 12,000 gallons per
day of wastewater from the laundry operation. Also, some liquid wastes
containing solvents were deposited on the ground outside the building.
The liquid wastes disposed on the ground were solvent-contaminated sludges
and water draw-off from the vapor recovery system. This water draw-off
contained from 60 to 100 ppm chlorinated solvents and amounted to about 30
gallons per week.
-------
\
-------
| J—/ c^UntogJark^y^Hfi
k •? r i \, -¦¦¦¦¦¦^ II
, \ ¦*¦¦
\ !• tyii^cea* Jl-
SRsALdSkeip • '. ?C
i 1 Sch'i'^M ii.i U,X i | ,
irt| f I-
~ LAKEWOOD WATER DISTRICT PRODUCTION WELL
SOIMCS: (IMS 7J*MINUTt QUADANOLE:
SttlUICOOM, WASHINGTON
I
i
FIGURE 2
VICINITY MAP
PONDERS CORNER F-FS
Seal* 1 "«¦ 2000*
CH2M
HHILL
-------
Contamination levels at and near this source have been measured as high as
the following values:
Groundwater movement dictates the spread of this contamination when the
wells are not operating. "This movement has not been fully characterized
but is known to flow generally in a northwest direction. When one or both
wells are operated, the major flow of the contaminants is toward the well.
WDOE took over enforcement and cleanup actions at the site under the
State's Water Pollution Control law. WDOE issued an administrative order
to the Cleaners in early summer of 1983 to assess the problem and clean up
the source. The former and current owners of Plaza Cleaners subsequently
signed a stipulated agreement with WDOE before the State Pollution Control
Hearings Board.
As a result of the order and agreement, Plaza Cleaners stopped disposal of
solvents to the ground and septic tanks, and much of the contaminated
surface soil has been dug out and replaced with uncontaminated soil. In
addition, commercial laundry operations ceased, decreasing the possibility
of further flushing of solvents into the groundwater from the septic tanks.
It is therefore believed that continuing discharge of contaminating
solvents into the ground has been stopped and that residual solvents in
the soil and the underlying aquifer constitute the source that is
presently contaminating Wells H-l and H-2.
The excavated contaminated soil was removed to the Plaza Cleaners parking
lot, where it remains today (albeit covered by plastic). Also, WDOE was
unable to get the Cleaners owners to develop and implement a plan for
protection of the aquifer from possible further contaminant releases from
Plaza Cleaners. This is important, as it is expected that a substantial
amount of solvents were flushed through the septic tank system, and remain
under the property as a continuing source of contamination.
EPA sent combination notice/104(e) letters to the current and former
owners of Plaza Cleaners in September 1983. In January 1984 WDOE turned
the site over to EPA. A federal-lead Superfund investigation was
reinitiated at that time.
Concentration
Parts per Billion (ppb)
Tri chl oroe thyl en e
Te trach 1 oroethy 1 ene
1,2-(trans)di chl oroe thyl ene
3,600 i n sludge
3,460,000 in soil
9,600 i n sludge
-------
C. Current Site Status
During December 1983, a 10-day pumping test was conducted on Well H-2.
Sample analysis indicated that the solvent concentrations decreased during
the first few days of testing and then tended to level off. Figure 3
shows the data from these tests for tetrachloroethylene and
1,2-(trans)dichloroethylene. Trichloroethylene (TCE) was also detected at
less than 50 ppb but was not quantifiable. Subsequently, in February
1984, TCE was quantified at 28 ppb. These data have been used to provide
a design basis for influent treatment.
Althoucfi the concentrations appeared to level off after several days
during the test, individual samples still showed variations from the
average. In addition, earlier tests at the source showed much higher
concentrations of contaminants and a greater margin for variation. For
these reasons, the contamination levels at the 2-day point during the pump
test were selected as a conservative design basis contaminant loading for
the treatment facility. A TCE level of 40 ppb was selected to provide
conservatism above the measured 28 ppb.
Design basis contaminant loadings are therefore as follows:
These values are assumed to apply to both wells because the wells are
close together and pump from the same aquifer. Either well would
therefore receive essentially the same input after long-term pumping.
All members of the chloroethylene series are central nervous system
depressants. Acute exposure results in lassitude and mental fogginess.
Complaints of mild irritation, lightheadedness, and mild headaches have
been reported. Prolonged occupational exposure to tri chl oroethylene has
produced impairment of the peripheral nervous system. The long-term,
low-dose effects on the central nervous system, however, have not been
well characterized in the scientific literature. Acute exposures can
produce damage to liver and kidneys. Tri chl oroethylene, however, is a
less potent renal toxin compared to chloroform or carbon tetrachloride.
Long-term toxicity of tri chl oroethylene appears to depend principally on
its metabolic products. As a result, other chemicals that enhance or
inhibit its metabolism may act to increase or decrease its toxicity.
Similar effects would be expected with the other two chl oroe thyl enes
because all three are metabolized by the mixed-function oxidases.
PPb
Tri chl oroe thyl en e
Te trach 1 oroethy 1 ene
1,2-(trans)di chl oroe thyl ene
40
250
360
-------
4801
80-
0 1
12/6/83
-r-
4
i
5
DAYS
—r-
7
—r-
8
T-
9
i
10
12/16/83
ITETRACHLOROETHYLENE
M Z (TRANS) DICHLORO ETHYLENE
FIGURE 3
PONDERS CORNER
10 DAY PUMP TEST — WELL H2
CONTAMINANT CONCENTRATIONS
-------
Although few studies have been performed, the three chemicals have not
been found to be teratogenic in laboratory animals tested. All chemicals
appear to require metabolic activation for any mutagenic effect.
Technical-grade trichloroethylene, which is mutagenic if metabolically
activated, contains epichlorohydrin and epoxibutane, which are more potent
mutagens than the pure TCE. 1,2-(trans)dichloroethylene has been found to
be nonmutagenic. There is generally insufficient evidence on the
mutagenicity of the three chemicals.
Both trichloroethylene and tetrachloroethylene have been shown to be liver
carcinogens in at least one strain of mice. No data are available on the
carcinogenicity of 1,2-(trans)dichloroethylene.
EPA has developed preliminary risk levels for human carcinogens based on
analysis by EPA's Carcinogen Assessment Group. Its estimates for
trichloroethylene and tetrachloroethylene are shown in Table 1. For
example, a trichloroethylene concentration of 2.7 ppb (with a risk level
of 10"®) is expected to increase the number of cancer deaths by one for
a million people exposed to the chemical in drinking water over a lifetime.
No data are available to describe the potential carcinogenicity of
1,2-(trans)dichloroethylene. A:ceptable drinking water concentrations for
noncarcinogenic risks are shown in Table 1 for this chemical.
The concentration design points, reached after 2 days of pumping at Well
H-2, are 40, 250, and 360 ppb for trichloroethylene, tetrachloroethylene,
and 1,2-(trans)di chl oroethylene, respectively. Table 2 shows the
contamination levels, the criteria, and comparisons among these values.
TABLE 2
LAKEWOOD WATER DISTRICT WELLS H-l AND H-2
COWARISON OF CONTAMINANTS AND CRITERIA
FOR DRINKING WATER
(CONCENTRATION--ppb)
Criteriaa Well Levelb Comparison0
Tri chl oroe thylene
Te trach1oroethy 1ene
2.7
0.8
40
250
360
14.8
313
13.3
1,2-(trans)di chl oroethylene 27
aAs established by Tacoma-Pierce County Health Department.
bBased on levels at 2 days during the 10-day pumping test.
cWell level divided by criteria. Factor by which the design point
contamination exceeds the criteria.
-------
Table 1
RISK LEVELS ASSOCIATED WITH
DRINKING WATER CONTAMINANTS (ppb)
Trichloroethylene
Tetrachloroethylene
1,2-(trans)dichloroethylene
Increased Cancer Risk1
l(f7
0.27
0.08
10~6
2.7
0.8
• 10
-5
27
8
Considered Acceptable
for Human Use
1-day
10-day Chronic
2,700
270
27
Assumes consumption of 2 liters of drinking water per day over a 70-year period. From
References lf 2, and 3.
Memorandum from William N. Hedeman, Jr., Director, Office of Emergency and Remedial
Response, to Lee M. Thomas, Acting Asst. Administrator, Office of Solid Waste and
Emergency Response, dated April 2, 1983.
¦»
'Tacoma-Pierce County Health Department, Washington.
-------
The Tacoma-Pierce County teal th Department has established target values
for these contaminants at the 10~® level for suspected carcinogens and
at 27 ppb for 1,2(trans)dichloroethylene. Based on these thresholds,
untreated water from Wells H-l and H-2 is considered a threat to human
heal th i f used for drinki ng water.
The greatest contamination has been found at 85-95 feet below the
surface. A plume of the solvents extends from Plaza Cleaners southeast to
Wells H-l and H-2, several hundred feet away. However, regional
groundwater flow is to the northwest. Since H-l and H-2 have not been
pumping (except for a few days) for several years, it is likely that a
plume also extends northwest of Plaza Cleaners. The extent of this plume
and the levels of contamination are unknown, as there are no monitoring
wells in that direction. Construction of those wells will be a part of a
future remedial investigation.
In the immediate vicinity of the Ponders well field, a perched aquifer is
usually present in Steilacoom gravels above a layer of relatively
impermeable Vashon till. The lateral extent and thickness of this till
layer are unknown in the area. Shallow wells typically tap this aquifer.
However, advance outwash deposits, with an average thickness of about 100
feet, are the most productive aquifers. Wells H-l and H-2 tap water from
the advance outwash deposits.
The surface soil is very permeable. In addition, there appears to be a
conduit between the shallow groundwater and the deeper aquifer tapped by
H-l and H-2, as the contaminated wells are only a few hundred feet from
the suspected source. Indications are that there is some form of well or
gravel pit at the terminus of the septic tank drainfield which allowed
contaminated effluent to directly reach the lower aquifer. This will be
verified in the remedial investigation.
Approximately 600 customers are normally served by Wells H-l and H-2.
Water is now being pumped from other parts of Lakewood Water District's
system to serve these people. However, the pressure is too low to provide
adequate fire protection and conservation measures have been put into
effect. Also, with heavier pumping of other Lakewood well s, and with H-l
and H-2 shut down, it is possible the contamination is flowing towards the
other wells in the system. Therefore, the problem, left unsolved, could
eventually affect the remaining 13,000 customers in the Water District.
D. Enforcement
Thus far, only the Plaza Cleaners at 12509 Pacific Highway SW in Lakewood
has been identified as a potentially responsible party. During the
remedial investigation it is likely that a few additional monitoring wells
will be constructed to determine if other responsible parties exist.
Virtually all commercial and residential buildings in Lakewood use septic
tanks, and it is conceivable that one or more additional (though probably
minor) sources could exist.
-------
The only enforcement action taken by EPA thus far has been the issuance of
CERCLA notice letters to the former and present owners of Plaza Cleaners.
WDOE issued an administrative order and signed a stipulated agreement
(discussed previously) with the owners. When the site was turned back to
EPA for action, EPA Headquarters, in consultation with WDOE, determined
that Fund money would be used for the completion of the Remedial
Investigation/Feasibility Study. The Region will decide at a later date
whether to attempt cost-recovery.
E. A1 ternatives Evaluation
The objectives of the proposed project are as follows:
1. Restrict the spread of contamination in the aquifer to reduce
ultimate clean-up needs and to protect the quality of water supply from
other well s.
2. Restore full water service to the area of the Lakewood Water
District that is adversely affected by the shutdown of Wells H-l and H-2.
This includes restoration of normal system pressure, flow, and
f i re-fi ghti ng capabi 1 i ty.
3. Facilities to meet these objectives should be operating at the
earliest practical date, preferably to meet the 1984 peak demand.
A treatment facility on the combined well output is proposed to meet these
objectives. This facility would be operated to purify the well water to
drinking water requirements, sized to provide the required capacity and
throughput, and operated year-round to control the spread of aquifer
contamination.
Nontreatment alternatives such as developing other wells or booster pumps
on the existing system will not meet the project objectives. Neither of
these approaches would limit the spread of contamination and both could
aggravate the problem by drawing the contamination toward the operating
wells. Locating and developing new wells could not be completed to meet
the schedule objective. A booster pump on another part of the system
would have to produce hicfier than normal operating pressure to deliver the
required flows. A detailed distribution system study would be needed to
verify the technical acceptability of this approach. Such a study,
design, and installation could not be completed in time to meet the
schedule objective. For these reasons, nontreatment alternatives are not
acceptable.
The treatment system performance criteria are as follows:
Water Supply. Wells H-l and H-2 have existed for years in the system, are
located in the same fenced site, have demonstrated capacity to meet the
system's pressure and flow requirements, and are the production wells
closest to the source of contamination. Adequate site space is available
-------
for a treatment facility. Operation of these wells will therefore meet
the District's water supply requirements and will provide the best
available means to limit further contaminant spread.
Treated Mater Quality. The Tacoma-Pieree County Health Department and
State Department of Social and teal th Services have established target
treated water quality criteria for the contaminants observed in Wells H-l
and H-2 as follows:
Treatment Capacity. Mr. R. Forster, superintendent of the Lakewood Water
District, indicated that historical operation of the system with Well H-l
producing 1 ,200 gpm and Well H-2 producing 800 gpm for a total of 2,000
gpm would meet the system's peak requirements.
Pumping Plan. This criterion is included to provide a basis for comparing
the elements of different system alternatives that depend on the amount of
water processed; for example, pumping costs and carbon consumption. The
numbers chosen are based on recent historical data for the three peak
summer months to supply adequate water to the residents plus a
contingency, and on a base flow rate of 1,000 gpm during the rest of the
year to restrain contamination spread. Annual treated volume on this
basis would be 590 million gallons.
Treatment Facility Life. A treatment facility capable of meeting the
water supply and contamination control objectives is needed until a
long-range, final remedial action (RA) is effective. The remedial
investigation/feasibility study assignment has just been made and is
expected to require about a year to complete. Authorization and design of
a final RA can be expected to require 6 months or more and construction,
another 6 months to a year. A short-term life of 3 years was therefore
selected for economic evaluations.
It is also possible that the facilities being considered in this study
will become part of the long-term RA and be required to operate for
several additional years. A design life of 15 years was therefore
selected for the facilities, and operations and maintenance costs were
developed for this longer period.
Treatment alternatives considered for this project are:
1,2-(trans)dichloroethylene
Tri chl oroethyl ene
Tetrachl oroethy 1 ene
27 ppb
2.7 ppb
0.8 ppb
o
No action
o
Conventional coagulation, sedimentation, and filtration
Reverse osmosis
-------
° Ion exchange
° Steam stripping
° Biological treatment
0 Activated carbon filtration
° Aeration
No Action. The no-action alternative would involve no treatment
facilities and either not operating the wells or operating them into the
system or to waste.
Not operating the wells is an unacceptable alternative because this course
would not meet the water supply or contamination confinement project
objectives. The existing threats to public health and welfare through
inadequate water supply and the potential for future contamination of now
clean wells would continue.
Operating the wells into the potable water system without treatment is
unacceptable on the basis of the resulting threat to public health. Such
action would result in drinking water contamination at levels exceeding
the accepted criteria for the specific contaminants present by factors
between about 13 to 300. Operating the wells to waste would limit the
further spread of contamination but would not protect the public health
and welfare, which would require restoration of an adequate water supply.
Discharge of untreated water to waste would create an added potential
threat to public health and the environment in open waterways. WDOE,
responsible for such discharges, has advised that some degree of treatment
and an NPDES permit would be required for routine discharge to waste from
these wells. Obtaining such a permit would require several months. This
alternative is therefore unacceptable on the basis of inadequate
protection of public health and welfare, potential threat of contamination
to a wider area of surface waters and the population, and the inability to
respond quickly to mitigate the existing problems.
Conventional Water Treatment, consisting of chemical addition to coagulate
colloidal material, sedimentation to partially separate the coagulated
material, and filtration to polish the treated water, is used to purify
many ground and surface water supplies. This process is not effective in
removing the organic solvents found in Ponders Corner well water. The
solvents would remain in solution and pass through such a treatment
system. This is therefore not a suitable treatment technology for this
application.
Reverse Osmosis (RO) can be used to separate dissolved materials in
water. In this process pressure is used to force water through a
semipermeable membrane that allows the passage of water molecules but
prevents the passage of most dissolved materials. Multiple stages may be
-------
arranged in series to achieve higher degrees of purity than for a single
stage. Membrane processes are somewhat imperfect with respect to organic
separations, so the produced water woul d still contain some organics.
Pretreatment requirements for reverse osmosis are substantial, capital
costs are high, and required operating pressures are high. For these
reasons, reverse osmosis is not considered a suitable treatment process
for thi s application.
Ion Exchange is an accepted method for removing ions from water. Ion
exchange is commonly used to reduce the hardness in water and to remove
specific metals. Only charged particles in solution or contaminants that
are reactive with the resin can be removed by ion exchange. The feedwater
is passed throucfi a bed of resin material, which is typically in the form
of small beads, that exchanges ions with those of the contaminant in
sol ution.
Ion exchange would be ineffective in purifying the Ponders Corner well
water because the contaminants do not produce ions in solution and will
not react with a resin.
Steam Stripping would involve boiling off the solvents in the well water
by raising the water temperature with steam. Subsequent cooling of the
water would then be needed before use in the water system. This process
is typically used in combination with a boiler plant where steam is
produced for some other purpose, and the stripping operation adds a small
cost increment. For this application, the facilities and fuel costs would
be very high, and it is therefore not a suitable alternative.
Biological Treatment has been applied on a limited scale to the cleanup of
several contaminated groundwater resources. Specially developed bacteria
are cultivated to feed on the specific contaminants in situ or in surface
reactors. These processes are typically proprietary and require pilot
work and development of the bacterium strain. Experience to date has been
with small systems operating at a few gallons per minute. They appear to
offer a low-cost cleanup alternative where the contaminants are suitable
food for the bacteria, where the contaminants are in the right
concentration range for the bacteria, and where cleanup time is not a
problem.
Bacteria are not particularly effective on the volatile organics
contaminating these well s, the concentration of organics is well below the
range needed for operation, and the time to implement such a system would
be much longer than desired. Also, no systems have been built that
operate at the flow rate required for Ponders Corner.
This alternative is therefore not applicable for treatment of the well
water.
-------
fctivated Carbon Filtration is an existing, conventional water treatment
technology that will remove the organic solvents present in these wells.
This technology involves the adsorption of the contaminants on the surface
area of carbon particles. The feedwater is passed through a bed of carbon
as in a conventional sand filter. Either pressurized or gravity tanks may
be used. A gravity system requires repumping the treated water to
discharge into the distribution system. For carbon adsorption treatment
to produce potable water, a second or lag unit usually operates in series
with the primary or lead carbon unit. Carbon treatment systems arranged
in this fashion allow the lag carbon vessels to protect against
contaminants passing into the water system when their carbon is exhausted
and can no longer adsorb the contaminants. This arrangement also enables
continuous operation of the treatment system when carbon is exhausted and
must be repl aced.
Several carbon system suppliers have treatment units for lease or purchase
that woul d meet the performance requirements of this proposed treatment
facility. Depending on the specific design and availability of units,
installation and startup can be accomplished on a short schedule that
could probably meet this project's needs.
A:tivated carbon filtration can therefore be considered further in the
more detailed evaluation of potentially suitable alternatives.
Air Stripping is the technology selected in early 1983 by EPA to treat the
well water from the City of Tacoma's Well 12A. Well 12A is contaminated
by several organic solvents including those found in the Ponders Corner
wells. Air stripping is a well established technology in which the
contaminated feedwater is distributed over the top of a loosely packed
fill material in a tower. As the water cascades down through the packing,
it breaks up into small droplets that provide a large surface area for
mass transfer. Air is forced through the packing from the tower base, and
volatile organics transfer from the water to the air at the air/Water
interface. The treated water is collected in a wet well below the tower,
chlorinated, and pumped into the distribution system.
Air stripping can therefore be considered further in the more detailed
evaluation of potentially suitable alternatives.
It is analyzed below, along with a carbon adsorption treatment system.
CARBON ADSORPTION TREATMENT SYSTEM
The preliminary design of the carbon adsorption system for the Ponders
Corner wells i s based on the design criteria of 2 to 4 gallons per minute
per square foot and 30 minutes empty bed contact time. The system is also
designed for lead-lag operation as described above. H/draulically, the
system will produce up to a maximum output of 2,000 gallons per minute.
Contaminant loading to the carbon system was based upon an approximate
yearly average flow rate of 1.62 mgd and estimated average contaminant
concentrations of 250-ppb tetrachloroethylene, 360-ppb
1, 2-(trans)dichloroethylene, and 40-ppb trichloroethylene.
-------
Actual carbon consumption is best determined from treatability tests. In
the absence of this information, carbon consumption can be estimated from
adsorption data in the literature. There was no information found in the
literature on the adsorption of the two major compounds when both are the
only contaminants present in water. Therefore, estimates of their
adsorption characteristics were made from data on the adsorption of these
compounds alone and with one or both compounds in the presence of other
similar compounds at the same concentrations as in the Ponders Corners
well water. A carbon consumption rate of 0.4 pound per 1 ,000 gallons was
estimated.
To satisfy the stated design criteria for the system characteristics at
Ponders Corner and to provide for lead-lag operation of the carbon
vessels, twelve 10-foot-diameter vessels with 12-foot-deep carbon beds
would be required. These twelve vessels would be arranged in two sets of
six parallel vessels in series.
Treated water from the carbon vessels would discharge into a wet well.
From the wet wel 1, the water woul d be pumped and discharged to the
Lakewood distribution system. The discharge from the wet well would be
chlorinated for disinfection. A process flow diagram of the carbon
treatment system is shown in Figure 4.
Both gravity and pressure carbon systems were evaluated and cost estimates
prepared. The cost of the carbon system components were based on
information obtained from carbon vendors. The results of the cost
estimates show that a treatment system employing a pressure or gravity
carbon system were approximately the same in cost. Based on this
evaluation and cost comparison, final costs are presented for a gravity
carbon treatment system because it provides more operational flexibility.
Ei ther a gravity or pressure system would be capable of producing water
that meets the required water quality criteria. The expected discharge
concentrations are shown in Table 3.
A summary of these treatment system costs is given in Tables 4 to 6. The
basis for these costs is discussed below.
The treated water from the carbon system will discharge into a wet well
before being pumped into Lakewood's distribution system. The required
size of the wet well is estimated to be approximately 4,000 to 5,000
gallons. For estimating purposes, a concrete wet well was assumed.
The wet-well pump sizing was based on a maximum flowrate of 2,000 gpm, an
average flowrate of 1 ,000 gpm, and a discharge pressure of approximately
65 pounds per square inch. These design values are preliminary and were
used for developing a cost estimate only. The pumping system cost
estimate was based on three vertical, 3-stage turbine pumps each sized to
deliver 1,000 gpm at 65 pounds per square inch, with 50 hp motors. One of
the three pumps would serve as a stand-by pump.
-------
FLOWMETER
jS.
TO DRAIN
6 CARBON GRAVITY
VESSELS IN PARALLEL
FLOWMETEI
-&i
TO DRAIN
-HX3-*
I
i SAMPLE
* TAP
rb
H1
EXISTING WELL
H2
EXISTING WELL
-00-
SAMPLE
TAP
(TYPICAL)
SAMPLE TAP
(TYPICAL)
SAMPLE
A TAP
CHLORINE
ADDITION
WET WELL
contribution
TTvJ SYSTEM
BOOSTER PUMPS
(3 IN PARALLEL)
control
FIGURE 4
PONDERS CORNER
PRELIMINARY FLOW DIAGRAM
CARBON ADSORPTION SYSTEM
-------
Table 3
PONDERS CORNER
ESTIMATED CARBON SYSTEM PERFORMANCE
Influent Effluent
Concentration Concentration Criteria
tPPh)
Tetrachloroethylene 250 ND 0.8
1,2-(Trans)Dichloroethyene 360 ND 27
Trichloroethylene 40 ND * 2.7
ND—Concentrations less than the lower limit of detection of 0.2 ppb
for tetrachloroethylene and trichloroethylene and 5 ppb for
1,2-(trans)dichloroethylene.
-------
Table 4
PONDERS CORNER ACTIVATED CARBON SYSTEM
CAPITAL COSTS
Procurement (Thous. $)
Carbon Vessels 525
Carbon Media 100
Wet Well 11
Relift Pumps 14
Chlorination t 6
Subtotal 656
Construction 423
Procurment and Construction
Subtotal 1,079
Professional Services 108
Total 1,187
Contingencies
Procurement (20%) 131
Construction (20%) 85
Professional Services (151) 16
Subtotal 232
Estimated Project Budget 1,419
-------
Table 5
PONDERS CORNER ACTIVATED CARBON SYSTEM
O&M COSTS
Labor ($/year)
Operator & Maintenance 6,700
Supervisor/Administration 7,200
Expenses
%
Power , 39,000
Carbon 224,000
Chemicals 1,000
Lab Tests 8,500
Vehicle 2,500
Estimated Annual O&M Costs 288,900
Notes: Power costs assume $0.034/kWh.
Carbon replacement costs assume $l/lb carbon.
Labor costs assume $16/hour.
Supervision/administration costs assume $50 per hour.
Laboratory tests assume one set of samples per week,
four samples per set, $40 per sample.
Chemical costs are for chlorine at $0.25 per pound.
-------
Table 6
PONDERS CORNER ACTIVATED CARBON SYSTEM
PRESENT WORTH COSTS
(Thous. $)
Project Construction Costs 1,419
Annual O&M Costs 289
First Year Total 1,708
3-Year Present Worth
%
Construction " 1,419
Salvage x * (436)
Present Worth O&M Costs—3 Years 718
TOTAL 1,701
15-Year Present Worth
Construction 1,419
Salvage 0
Present Worth O&M Costs—15 Years 2,198
TOTAL 3,717
Notes: Salvage value for carbon vessels, pumps, and
chlorination system only; straight-line de-
preciation over 15 years assumed.
Annual costs were discounted at 10 percenti
-------
The cost estimate includes a chlorination system to disinfect the
discharge from the wet well. A chlorine residual of 0.2 ppm is required.
For design purposes, a chlorine dosage of 1 ppm was assumed. The cost
estimate is for a chlorination system that will deliver up to 30-pounds
per day of chlorine with a 10 to 1 turn-down ratio. The system includes
scales for two 150-pound chlorine cylinders, an injector, and controls to
proportion chlorine dosage with flowrate.
Construction costs for Ponders Corner were based on the construction costs
for the Tacoma Well 12-A project. Construction costs for Ponders Corner
were assumed to be the same percentage of procurement costs as for the
Well 12-A project. This method was judged to be a valid approach based on
the similar level of complexity of the two projects. Costs for piping,
valves, electrical, and instrumentation and controls are included in the
construction costs.
Professional services include: design and procurement completion;
approval and change coordination; permits, site access, and agency
coordination; construction and subcontract administration; overall
management, control, and reporting; community relations support; and other
related expenses. These costs were estimated from experience with the
Well 12-A project. Because the carbon system and air stripping system
have similar complexity, professional services costs were assumed to be
the same for both systems.
Contingencies of 20 percent for the procurement and construction phases of
the project and 15 percent for professional services were used.
Contingencies for the carbon system are higher than those used for the air
stripping system due to a lesser degree of detail in the estimate.
Yearly operation and maintenance costs include carbon replacement, power,
laboratory, and labor costs. Carbon replacement costs were based on an
estimated consumption rate of 0.4 pound per 1 ,000 gallons. Based on a
yearly average flow of 1.62 mgd, approximately 224,000 pounds of carbon
are required per year. A carbon replacement cost, including supply,
regeneration, and disposal services, was quoted by a carbon vendor at
$1.00 per pound.
Power costs were based on an average discharge flow rate of 1 ,500 gpm for
3 months of the year and 1 ,000 gpm for the remaining 9 months. It was
assumed that two 50-hp relift pumps and the 150-hp well pump would be
required to provide 1 ,500 gpm. One 50-hp pump and the 100-hp well pump
would be required to provide 1 ,000 gpm. A power cost of $0,034 per kWh
was assumed.
Labor costs assumed 8 hours of operation and maintenance per week for 52
weeks at a labor rate of $16 per hour. Vehicle costs of $6 per hour for
the same number of hours per week were also assumed. Supervision and
administration costs assumed 12 hours per month at $50 per hour.
-------
The annual cost for operation and maintenance (OSM) of the carbon
treatment facilities only is estimated at $273,300. 0&M of the wells is
estimated at $15,580 a year.
AIR STRIPPING TREATMENT SYSTEM
The preliminary design of the air stripping system for Ponders Corner is
based in large part on the pilot work performed for the Tacoma Well 12-A
project. From this pilot work and review of the 1 iterature, it has been
round that gas-to-liquid ratios of 200 to 300-to-l on a volume basis will
achieve the removal rates of chlorinated organic solvents necessary to
produce potable water from the groundwaters at Ponders Corner and Well
12-A. Mass transfer coefficients were developed from a model in the
literature that was successfully used in the design of the Wei 1 12-A air
stripping system.
The air stripping conceptual design for Ponders Corner was based upon
tetrachloroethylene, which is the most difficult contaminant to remove.
The other contaminants would be removed to levels below the design
effluent criteria. Table 7 shows the estimated tower performance for the
contaminants present.
TABLE 7
PONDERS CORNER AIR STRIPPING SYSTEM
ESTIMATED TOWER PERFORMANCE
Initial Final Design
Concentration Concentration Criteria
tPPb) (ppb) (ppb)
Tetrachloroethylene 250 Less than 0.8 0.8
1,2-(Trans)dichlo-
roethylene 360 ND 27
Tri chloroe thylene 40 ND 2.7
ND--Less than lower limit of detection of 0.2 ppb
for trichloroethylene and 5.0 ppb for
1,2-(trans)dichloroethy1ene.
The preliminary design of the air stripping system calls for two stripping
towers in parallel, each capable of treating 1,000 gallons per minute for
a total treatment capacity of 2,000 gallons per minute. Each tower would
have a packing depth of approximately 25 feet.
-------
Treated water from the stripping towers would discharge into a wet well.
From the wet well the water would be pumped into the Lakewood distribution
system. Discharge from the wet well would be chlorinated for
disinfection. A process flow diagram of the treatment system is shown in
Figure 5.
A summary of the costs for the air stripping treatment system is given in
Tables 8 to 10. A discussion on the development of these costs is given
below. Because of the similarity in size of the Tacoma Well 12-A
stripping towers, costs from the 12-A project were used as a basis for
some of the costs developed for Ponders Corner.
Each of the two air stripping towers would be 12 feet in diameter with a
packing depth of approximately 25 feet. The overall tower height to the
top of the discharge stack would be approximately 55 feet but may vary,
depending on the height of the stack and final design considerations.
Costs for the tower shell s were based on the tower costs for the Tacoma
Well 12-A project. Towers for the Well 12-A project are 12 feet in
diameter with an overall height of approximately 50 feet. Adjustments
were made for the greater packing depth required at Ponders Corner, the
possible need for an intermediate media support plate, and inflation.
Each tower would require approximately 2,700 cubic feet of media. Several
media suppliers were contacted, and cost information vailing from
approximately $8.00 to $13.50 per cubic foot was received. For purposes
of this cost estimate, the higher price quote was used.
One fan for each stripping tower would be required. The fans were sized
for an air flow rate of 27,000 cubic feet per minute and a pressure drop
of 10 inches of water. The power requirement for each fan at these
operating criteria, assuming 70 percent efficiency fans, is 60 hp. Cost
for the fans includes silencers, and was based on a fan vendor's
i nformation.
As with the carbon adsorption system, this system will require a wet well
and pumps for discharge to the Lakewood distribution system. "These items
will be the same size and capacity as they were for the carbon system.
The wet well volume woul d be 4,000 to 5,000 gallons. Pump costs were
based on three vertical turbine pumps, each rated at 1,000 gallons per
minute, and a discharge pressure of 65 pounds per square inch. One of the
three pumps would serve as a standby.
A chlorination system for treated water disinfection is also included in
the cost. It would have the same capacity and components as the
chlorination system for the carbon treatment system.
A chlorine solution would be cycled through the towers periodically to
clean the packing. The cost of this system is included in the
construction cost.
-------
-------
Table 8
PONDERS CORNER AIR STRIPPING SYSTEM
CAPITAL COSTS
Procurement (Thous. $)
Towers 86.5
Media 86.5
Fans/Silencers 21.0
Wet Well 10.7
Relift Pumps 13.8
Chlorination , 6.5
" — %
Subtotal . 225.0
Construction 145.0
Procurement and Construction
Subtotal 370.0
Professional Services 108.0
Total 478.0
Contingencies
Procurement (10%) 22.5
Construction (15%) 21.7
Professional Services (15%) 16.2
Subtotal 60.4
Preliminary Estimated
Project Budget $540
I
-------
Table 9
PONDERS CORNERS AIR STRIPPING SYSTEM
O&M COSTS
Labor ($/year)
Operator & Maintenance 6,700
Supervisor/Administration 7,200
Expenses
Power §6,000
ChemicaIs 1,000
Laboratory Tests 8,500
Vehicle 2,500
Estimated Annual O&M Costs 81,900
Notes: Power costs assume $0.034/kWh.
Chemical costs are for chlorine at $0.25/pound.
O&M labor costs assume $16/hour, Supervisor/Admin.
"at $50/hour.
Vehicle costs assume $6/hour.
Laboratory tests assume one set of samples per
week, four samples per set, $40 per sample.
-------
Table 10
PONDERS CORNER AIR STRIPPING SYSTEM
PRESENT WORTH COSTS
(Thous. $)
Project Construction Cost 540
Annual O&M Costs 82
First Year Total 622
3-Year Present Worth * *
*
Construction 540
Salvage (171)
Present Worth O&M Costs—3 Years 203
TOTAL 572
15-Year Present Worth
Construction 540
Salvage 0
Present Worth O&M Costs—15 Years 623
TOTAL 1/163
Notes; Salvage value for towers, media, pumps, fans, and
chlorination system assumed using straight-line
depreciation.
Annual costs were discounted at 10 percent.
-------
Construction costs are based on the construction costs for the Tacoma Well
12-A installation. Professional services costs were also estimated from
the Tacoma Well 12-A project. Contingencies of 10 percent for procurement
and 15 percent for construction and professional services were used.
Operating and maintenance costs for the air stripping system are the same
as the O&M costs for the carbon system except that carbon replacement is
not required and there is an additional cost for air blower power (two
blowers at 60 hp each for 3 months, one blower at 60 hp for 9 months).
Annual operations and maintenance costs for the air stripping treatment
facilities only are estimated at $66,320. O&M costs for wells only are
estimated at $15,580 a year.
F. Community Relations
Documents made available for public comment included:
"Focused Feasibility Study: Ponders Corner Well Water Treatment
Facility, Lakewood, Washington," May 1984.
"Remedial Tttion Master Plan: Lakewood Water District Well s,
Lakewood Washington," November 7, 1983.
"Report of the Groundwater Investigation: Lakewood, Washington,
October 1981 to February 1983," February 1983.
"Fact Sheet: Ponders Corner Well Water Treatment Facility," May 1984.
The Focused Feasibility Study is the document we sought comments on. The
others were provided for background.
The public was notified of the public comment period, extending from May 7
to May 21 , 1984 through several channels. The Lakewood Press, a local
paper distributed to all Lakewood residents, was provided information for
a story on the proposal in late April. On May 3, 1984 EPA issued a press
release discussing the proposed initial remedial measure and announcing
the public meeting. A story was subsequently run in the Tacoma
News-Tribune (the Tacoma area's largest daily newspaper). Also, several
local radio stations ran a story on the wells and announced the meeting.
EPA's contractor, CH2M Hill, prepared a community relations plan for
this project. As part of that effort a mailing list of over 60 persons
having an interest in the project was developed. The press release and
fact sheet were mailed to those 60 individuals on May 3, 1984.
The public meeting was held at 7:00 p.m. at the Lakewood Branch of the
Pierce County Library. Two TV stations and one radio station had crews
present and ran subsequent stories in the Seattle and Tacoma areas. Also
in attendance were representatives from WDOE, Tacoma-Pierce County Health
Department, Lakewood Water District, Tahomans for a Healthy Environment, a
Pierce County Council member, the owner of Plaza Cleaners and his
attorney, and several residents of Lakewood.
-------
The comments were generally supportive. Some concern was expressed about
spending additional money at the site for further investigations, and
questions were asked regarding who was going to pay for the project. Some
speculation was given on other potential sources. A Community Relations
Responsiveness Summary is also attached.
G. Consistency wi th other Environmental Laws
Both the activated carbon system and the air stripping system alternatives
would be in compliance with all environmental laws and regulations. The
only environmental law or regulation applicable to the activated carbon
system would be the Resource Conservation and Recovery Act regulations
dealing with the handling and disposal of hazardous wastes. The carbon
would periodically be removed from the system and replaced with clean
carbon. The used carbon woul d contai n hi gh amounts of hazardous
materials, namely the three solvents absorbed from the well water. The
carbon would be disposed of at an EPA approved landfill, incinerated, or
regenerated by an approved firm.
The only environmental law or regulation applicable to the air stripping
system would be Occupational Safety and Health Administration (OSHA)
8-hour ground level air standards. Listed below are estimates of the
8-hour average levels of contaminants at ground level, emanating from the
towers.
Estimated 8 OSHA 8
Contaminant four Average Hour Standard
1,2 Transdichloroethylene 9.1 ppb
Tri chl oroethylene 0.8 ppb
Tetrachloroethylene 3.7 ppb
200,000 ppb
100,000 ppb
100,000 ppb
Obviously the contamination levels will only reach a small fraction of the
OSHA standard. An air emission permit would be obtained from the Puget
Sound Air Pollution Control Agency.
Recommended Alternative
Both an activated carbon system and an air stripping system are
technically acceptable and have substantial past operating experience.
Either system, properly designed and operated, would produce treated water
within the prescribed limits. Hie treated water from a carbon system
would have residual contaminants in the nondetectable range, and treated
water from an air stripping system would have residual contaminents at or
below the established 1 imits.
An environmental concern with a carbon system is the possible spread of
contaminated carbon during the frequent cycles of handling, transport, and
offsite regeneration that would be required. Fully contained piping
systems would transfer the spent cabron to and from a tank truck used for
-------
transport. These systems are used extensively and will normally eliminate
spills. Should a spill occur, the contamination wil 1 spread only with the
carbon since it is bound into the carbon by the adsorption process.
Cleanup of such an event would be accomplished by recovering the carbon,
and the hazard to the population and workers would be low.
Environmental concerns with an air stripping system are the spread of
contaminants through the air discharge and objectionable noise from the
fans. Fan inlet silencers will effectively eliminate any increase in
noise levels at this site, as indicated by the experience of the EPA's
Well 12A facility in Tacoma. Calculations and tests on the 12A air
stripping system showed negligible, nonmeasurable air and ground-level
concentrations of contaminents. The tower air flow for the Well 12A
system and the proposed air stripping system for Ponders Corner are almost
identical, and the expected contamination levels at Ponders Corner are
about 75 percent of the design loading basis at Well 12A. For these
reasons, ground-level concentrations of contaminants similar to Well 12A
would be expected for Ponders Corner.
Both systems are capable of being implemented in a short time; the
schedule and startup date would be controlled largely by the ability to
maintain continuity during design, procurement, and construction.
The cost of a carbon system is estimated to be substantially greater than
for an air stripping system. Cost comparisons developed in this study are
shown in Table 11.
Table 11
SYSTEM COMPARATIVE COSTS
(Thousands $)
Air
Carbon Strippi ng
First Cost 1,419 540
Annual 0AM .289 82
First Year Total 1 ,708 622
3-Year Present Worth 1 ,701 572
15-Year Present Worth 3,717 1,163
On the basis of these comparisons and the substantial cost difference that
exists between these two systems, it is recommended that the air stripping
system be selected because it is technically sound, environmentally
acceptable, and the most cost-effective solution for this project. Air
stripping is the most cost-effective alternative whether the towers are in
place only three years, 15 years, or longer.
-------
H. Operation and Maintenance (0 & M)
0 & M costs for the air stripping system are discussed above in the Carbon
Adsorption Treatment System and the Air Stripping Treatment System
subparts of the Alternatives Evaluation. The annual 0 & M cost is
estimated at $82,0UU.
Negotiations with the State on 0 & M funding are almost complete. For the
first year of operation the Lakewood Water District has agreed to pay the
0 & M costs it would have to pay to operate the wells if they were not
contaminated. This amounts to approximately $15,580. This money would
come from fees collected to supply the water to its customers. The
Washington Department of Ecology has agreed to pay 10% of the remaining 0
& M costs for the first year out of the State's Superfund. The Lakewood
Water District will seek a rate increase to cover 100% of 0 & M costs for
all succeeding years.
Ownership of the treatment system, and liability on the site, is being
worked out in a separate agreement with the Lakewood Water District and
WDOE. The system will be located on Lakewood Water District property.
I. Schedule
Some key milestones and approximate dates for project implementation are
listed below.
Milestone
Target Date
Upon completion of RI/FS
May 31, 1984
Complete Enforcement Negotiations
Approve Initial Remedial Action
(signs ROD)
Award Superfund State Contract for
Design and Construction
May 31, 1984
Complete Design
Award Cooperative Agreement for O&M
Start Construction
June 12, 1984
August 15, 1984
June 13, 1984
Complete Construction
August 31, 1984 (one tower
operational August 1, 1984)
-------
J. Future Actions
An obligation of Fund monies has been made to complete a full RI/FS
beginning summer 1984. A scope of work has been approved and CH2M Hill
will begin working on the work plan by June. The remedial investigation
will likely include the construction of several additional monitoring
wells to determine 1f any other sources of contamination exist in the
area, and to find out how far the contaminant plume now extends. Since
Wells H-l and H-2 have been shut down, it is believed the contamination
has been flowing in a different direction. This information is. Important
in designing a final remedial action for the well contamination problem.
In addition, more work 1s proposed for the Plaza Cleaners site to
determine if 1t is a continuing source of contamination. Specifically,
soil samples will be taken and an Investigation of the septic tank
dralnfield 1s planned. The dralnfleld, and suspected well at the end of
1t, have never been found. The soil 1n the area of the drainfield and
well may remain contaminated, even though no solvents now enter the septic
tanks.
Following that investigation, a feasibility study will be prepared,
assessing various options for remedying the situation. The same process
outlined 1n this Record of Decision will likely be used to select the
alternative to be Implemented. Negotiations with responsible parties on
implementing the remedial action may take place at that time.
------- |