ROD-RlO-South Tacdma Channel
Superfund Reccid of Decision (EPA Region 10)
South Tacoma.Channel, Well 12A, Tacoma
Washington, May 1985
(U.S.) Environmental Protection Agency
Washington, DC
3 May 85
U.S. Depcstnwot of Conws^rce
Technkd WerriwtJon Service
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United States
Environmental Protection
Agency
OWceof •
Emergency and
Remedial Reepom*
: EPA/ROD R10-85/004
:: May 1985
Superfund
Record of Decision:
South Tacoma Channel-Well 12A, WA
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TECHNICAL REPORT DATA
(Pleas* read !~.:-SS (Till Report>
None
21. NO. OF PAGES
20. SECURITY CLASS :T>>itpofei
None
23. PRICE
EPA Fww 2220-1 (R**-4-77) BMKVIOU* COITION i » OMOLKTC
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RECORD OF DECISION
REMEDIAL ALT£RNATIVE SELECTION
Site: South Tacoma Channel - Well 12A
Tacoma, Nashington
DOCUMENTS REVIEWED:
I am basing my decision primarily on the following documents
describing the cost-effectiveness of remedial alternatives for the Well
12A site:
0 Remedial Investigation/Feasibility Study for South Tacoma Channel,
WA. CH2M Hill, July 1984.
0 Letter reports, dated January 4, 18 and 23. 1985, by CH2M Hill
0 Record of Decision and Supporting Documents for the Initial Remedial
Measure, dated March 18. 1983.
0 Responsiveness Summary, dated March, 1985.
0 Materials provided by the potentially responsible parties and
incorporated by reference into the Responsiveness Summary.
0 Staff summaries and recommendations.
DESCRIPTION OF SELECTED REMEDY:
0 Ccitinue to operate the IRM (treatment of Well 12A effluent) until
such time that the source control and remedial measures render the
IRM unnecessary.
0 Extract and treat the groundwater at the source to remove volatile
organics, followed by discharge of a major portion of the treated
extiaction well effluerl into Commencement Bay via an existing storm
sewer. The remaining treated extraction well effluent is to be
recharged to the aquifer at the soi.rce area by means of a drain field
in order to provide flushing of contaminants in the soil column.
0 During the design phase, drill a.id sample up to 5 additional 30-foot
soil test borings in o^der to better define the extent of soil
contamination.
0 Remove an appropriate length of railroad track adjacent to the Time
Oil property and excavate the discolored, oily, fine-grained filter
cake and soils under and adjacent to the railroad spur. The
excavated materials wii1 include the discolored, fine-grained
materials mentioned aoove, plus approximately 1 additional foot of
undercut. (The approximate average depth of removal is 6 feet).
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0 Additional undercutting will be performed in areas where small
incremental increases in soil excavation will produce relatively
large increases in solvent removal (and hence, reduce the duration of
and increase the reliability of the soil flushing process.) The
incremental increases In soil excavation will be limited to 152 by
volume of the proposed soil excavation.
0 Install the drain field piping in the excavated areas and cover with
a permeable material to protect the piping and prevent direct human
contact with underlying soils.
0 Pave or place soil cover on the portions of the unpaged Time Oil
parking lot not subject to excavation and flushing, in order to
prevent direct human contact.
0 Transport *and dispose of all excavated, contaminated soils in a
RCRA-permi tted landfi11.
0 Maintain institutional controls prohibiting withdrawal of groundwater
by private parties in portions of the aquifer where the level of
. hazard is in excess of 10"'.
0 Monitor groundwater consistent with provisions of RCRA and with
sufficient detail so as to be able to evaluate the performance.of the
treatment system.
0 After two years of operation, evaluate the effectiveness of the
groundwater extraction and treatment system in order to determine the
endpoint level of treatment for the groundwater and soil at the
"source area. The need for capping and other close-out requirements
will be determined at this time.
DECLARATIONS:
Consistent with the Comprehensive Environmental Response,
Compensation, and Liability Act of ',930 (CERCLA); and the National
Contingency Plan (40 CFR Part 300); I have determined that the remedial
action consisting of the extraction, treatment, and discharge of
groundwater In conjunction with soil removal and flushing at the South
Tacoma Channel Well 12A site is the most cost-effective remedy and
provides adequate protection of the public health, welfare and the
environment. The remedial action includes the maintenance of
institutional controls with which to prohibit withdrawals of groundwater
from the the area of the plume of contamination, ana the selection of the
endpoint of groundwater and soil treatment at the source area. Selection
of the endpoint levels of treatment is to be done in such a way so as to
minimize the extent of the aquifer requiring long-term institutional
controls w'lile at the same time, provide a technically feasible arid
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cost-effective remedy. The levels w'. 11 taKe Into account the site
specific and regional characteristics and will be protective of the public
health and the environment. The endpoint levels of treatment are to be
evaluated by the Regional Administrator after two years of system
operation. The State of Washington has been consulted and agrees with the
approved remedy.
The Regional Administrator shall have the authority to approve
modifications to the choice and operation of certain aspects of the remedy
as discussed in the Summary of Remedial Alternatives Selection insofar as
those modifications are equivalent in effectiveness and cost or are
necessary for the protection of health or the environment.
In addition, the action may require future operation and maintenance
<0&M) activities to ensure the continued effectiveness of the remedy.
These activities will be considered part of the approved action and
eligible for Trust Fund monies until such time that the Regional
Administrator makes the decision regarding the endpoint level of treatment
for soils and groundwater. At the time when the levels are set. the
Regional Administrator will also decide on the future status and funding
of OiM.
I have also determined that the action being taken is appropriate
when balanced against the availability of Trust Fund monies for use at
other sites. In addition, the off-site
contaminated material from the site is
remedial actions and is necessary to prct
the environment.
transport and disposal of
re cost-effective than other
ct public health, welfare, or
HAY 31965
Date
Jack W. Mcuraw
Actin.g/Acsi stant Admini strator
Offic;ff of Solid Waste and Emergency
Response
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SUMMARY OF
REMEDIAL ALTERNATIVE SELECTION
SITE: South Tacoma Channel-Moll 12A
SITE LOCATION AND DESCRIPTION
The South Tacoma Channel. Well 12A site is in the City of Tacoma,
Washington (Figure 1) and includes industrial, commercial and residential
areas. The site is within the Commencement Bay drainage area and lies at
an elevation of approximately 300 feet above sea level. Both the
underlying groundwater aquifer and portions of the surficial soils show
contamination with organic solvents.
The approximate area of suspected groundwater contamination is shown
on Figure 2 and encompasses about 100 acres. The underlying geology
consists of gravel, sand and silts of glacial origin, and is illustrated
in Figure 3 which shows a cross section of the aquifer. Well 12A and
other drinking water production wells draw from the hign permeability
layers underlying the complex structure of unsaturated layers of
intermediate and low permeability.
SITE HISTORY
Groundwater Contamination
In September 19C1, chlorinated organic solvents were detected in
Tacoma Well 12A. The well was voluntarily removed from service by the
City in coooeration with the State Department of Social and Healtn
•Services. Well 12A is ore of 13 wells used by the City to meet peak
summer and emergency water demands. During July, August and September,
the wells supply as much as 4C percent of the system demand and have a
capacity of 45 mgd.
In April 1982, the United States Environmental Protection Agency
authorized a remedial investigation to determine the type and extent of
the contamination, to identify its migration and to locate the source(s).
The contaminants at Well 12A were identified as follows:
1,1,2.2-tetrachloroethane 17 to 300 ppb
1,2-transdichloroethylene 30 to 100 ppb
Trichloroethylene 54 to 130 ppb
Tetrachloroethylene 1.6 to 5.4 ppb
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BURLINGTON
NORTHERN
RAILROAD
SOUTH TACOMA
CHANNEL
STUDY AREA
• City of Ttcom*
Scale: 1 inch • ttmile
FIGURE 1
SOUTH TACOMA CHANNEL
VICINITY MAP
South Tacoma Channel ROD
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A ..
i r -*
- l - '
./i
I ••/::
BURLINGTON NORTHERN
RAILROAD
f
. '."* BURLINGTON
i ' NORTHERN
!:/ .
f * SOUTH 35TH STREET
'APPROXIMATE AREA OF
GROUND WATER CONTAMINATION
x 'RESIDENTIAL I
» AREA . • < *
_ 1
r ,r- '
EXPLANATION
• Ctty of Tc
Scalt: 1 inch - 625 fttt
Reproduced t»om
best avAilabic copy
FIGURE 2
MONITORING WELL AND
CITY WELL LOCATIONS
Couth Ticoma Channtl ROD
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SCHEMATIC NORTH-SOUTH CROSS SECTION OF AQUIFER
COW-05
GROUND LINE
CUW-03
CBW-OI
CBW-07
D
SCREENED
INTERVAL
LIMITS OF HIGH
PERMEABILITY
LEGEND
HIGH
PERMEABILITY
INTERMEDIATE
PERMEABILITY
LOW
PERMEABILITY
-330
-300
•290
ELEVATION ABOVE
SEA LEVEL IN FEET
-200
-ISO
-IOO
FIGURE 3
from: Black & Ueatch, Remedial
Investigation Tacoma Well 12A
South Tacoma Channel ROD
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-2-
Remedlal Investigation
During the remedial investigation, eleven monitoring wells were
"Installed. By measuring groundwater elevation in the wells, it was
determined that the natural (undisturbed by well field pumping)
groundwater flow direction was from west to east with a relatively flat
gradient and therefore, a low flow velocity. The study also determined
that the major source of contamination was generally northeast of Well
12A. A specific source was not identified. Under these conditions, with
the wellfield shut down most of the year, the contaminant plume moves
slowly away from the production wells. However, under the influence of
production well pumping action, the natural gradient is reversed and the
contamination is drawn towards the operating wells.
One conclusion of the Remedial Investigation was that operation of
Well 12A would intercept the contamination drawn from the source area even
if other production wells were pumping. In effect. Well 12A would provide
a barrier to the spread of contamination and protect the rest of the
wellfield. If Well 12A were not operated to provide a barrier, other
operating wells would draw the contaminant plume and vould be lost for use.
Well 12A FFS/IRM
To avoid the potential loss of the wellfield during the approaching
summer peak, water demand period, EPA, in January 1983, authorized a
focused feasibility study to determine a cost effective treatment system
for the output of Well 12A. Treatment of the wellwater was necessary to
achieve a quality that would permit discharge to Commencement Bay, or
would permit its use in the City water system.
The initial remedial measure for Well I2A treatment was determined to
be an air stripping system consisting of five packed towers operatirg in
parallel at a total flow rate of 3,500 gpm and discharging treated water
to either Commencement Bay or to the City's water system depending on
measured quality and the City's needs. The decision level used to
determine whether the treated well water would be used in the City wat°r
system or discharged to the bay was the 10"s level of hazard at the tap
(after dilution in the system).
Construction of this treatment system was authorized in late March
1983, an
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-3-
Operation of the Well 12A treatment s>stem by the City of Tacoma will
continue on a seasonal basis to protect the wellfield.
Supplemental Investigations
Because the remedial investigation completed in late 1982 identified
a general source area only and not a specific site. EPA authorized in
December 1982 a study of historical solvent use and disposal practices in
the suspect area. Records of past investigations by the Tacoma/Pierce
County Health Department, Tacoma Water Division and the State Department
of Ecology were reviewed and interviews were conducted with owners of
numerous businesses in the area. A follow-up study focused en the
historical uses and disposal of 1,1,2,2-tetrachloroethane in the vicinity
of Well 12A. Theso studies reduced both the number and location of
potential sources of the contamination.
In mid-May 1983, EPA authorized a supplemental remedial investigation
to define further the extent of groundwater contamination and to attempt
to locate the source. Four monitoring wells were installed and these, as
well as the previously installed monitoring wells, were sampled several
times between July and November. One of the new wells (near the Time Oil,
Fleetline and Burlington Northern property"1 showed levels of
trichloroethylene, 1,1,2,2-tetrachloroethane and 1,2-trans-
dichloroethylene in the low ppm range; substantially higher than detected
in other wel1s.
With the apparent source area narrowed down substantially. EPA
obtained air and near surface soil samples along the Burlington Northern
railroad spur adjacent to the Time Oil plant. Air sampling results showed
very low levels of contaminants, but soil samples were very high in
trichloroethylene and 1.1,2,2,-tetrachloroethane.
Source History
Research into the past ownership and activities on these properties
indicated that waste oil and solvent reclamation processes were used and
that some of the spent filter rake was useu to build the railroad spur.
The use of the Time Oil site for oil .••"cycling and related operations
dates back to 1927 when William Pal in began operations under the name of
Pal in and Son. In 1933. the business name was changed to National Oil and
Paint. The two main activities of the businesses were waste oil recycling
and paint and lacquer thinner manufa'curing.
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-4-
The waste oil recycling process consisted of collecting waste oil in
a large tank, adding chemicals such as sulfuric acid, and pressurizing and
heating the contents of the vessel. This process resulted in the
formation of a tar-like sludge on the bottom of the tank which was removed
and disposed of. Absorbents and clay materials were also added to the
oil. The sludge was filtered from the oil, and the resulting filter cake
was disposed of or stored in various piles on the site. Some of this
sludge was also used for fill around the site.
The paint and lacquer thinner manufacturing involved the use of many
solvents that were stored on the site in barrels which may have leaked
their contents into the soil.
Prior to purchase of the property by Time Oil, Inc., in 1964. the
remaining barrels and drums of solvent were removed from the site. A^ter
Time Oil purchased the property, operations continued under the name
National Oil and Paint until 1972. During this period. National Oil was
Involved only in waste oil recycling. Waste sludges and filter cakes were
not known to be stored on the site during this period.
In 1972. Time Oil leased the facilities to Golden Penn, Inc. Golden
Penn operated on the site until 1976. before going out of business as a
result of a destructive-fire. In 1975 and 1976, Golden Penn was ordered
by the State of Washington to clean up the site by removing some of the
filter cake and spilled oil from the ground.
In 1976, Time Oil resumed operation at the site. Since then their
operation has been limited to canning oil brought to the site in bulk
containers. In 1982, the Burlington Northern Railroad spur was extended
by Time Oil to its present lenqth so that oil could be delivered by tanker
car. During the construction of the spur, some of the filter cake or
sludge material stored on the site was used in the roadbed.
CURRENT SITE STATUS
During the remedial investigation, the extent of soil and groundwater
contamination near the Time Oil plant was explored by means of surface
soil samples, shallow and deep soil borings and monitoring wells. Figure
4 shows the locations of these sampling points.
Groundwater surface contours and elevations are shown on Figure 5 for
the condition where Well 12A and the rest of the wellfield had been shut
down for a long period of time. The flat gradient resulting in low water
velocities is indicated by the wide spacing between contour lines. The
natural flow, in the absence of wellfield pumping, is from Well 12A toward
the Time Oil site.
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-4-
The waste oil recycling process consisted of collecting waste oil in
a large tank, adding chemicals such as sulfuric acid, and pressurizing and
heating the contents of the vessel. This process resulted in the
formation of a tar-like sludge on the bottom of the tank which was removed
and disposed of. Absorbents and clay materials were also added to the
oil. The sludge was filtered from the oil, and the resulting filter cake
was disposed of or stored in various piles on the site. Some of this
sludge was also used for fill around the site.
The paint and lacquer thinner manufacturing involved the use of many
solvents that were stored on the site in barrels which may have leaked
their contents into the soil.
Prior to purchase of the property by Time Oil. Inc., in 1964, the
remaining barrels and drums of solvent were removed from the site. After
Time Oil purchased the property, operations continued under the name
National Oil and Paint until 1972. During this period. National Oil was
involved only in waste oil recycling. Waste sludges and filter cakes were
not known to be stored on the site during this period.
In 1972. Time Oil leased the facilities to Golden Penn, Inc. Golden
Penn operated on the site until 1976, before going out of business as a
result of a destructive fire. In 1975 and 1976, Golden Penn was ordered
by the State of Washington to clean up the site by removing some of the
filter cake and spilled oil from the ground.
In 1976, Time O'l resumed operation at the site. Since then their
operation has been limited to canning oil brought to the site in bulk
containers. In 1982. the Burlington Northern Railroad spur was extended
by Time Oil to its present length so that oil coula be delivered by tanker
car. During the construction of the spur, some of the filter cake or
sludge material stored on the site was used in the roadbed.
CURRENT SITE STATUS
During the remedial investigation, the extent of soi i and groundwater
contamination near the Time Oil plant was explored by means of surface
soil samples, shallow and deep soil borings and monitoring wells. Figure
4 shows the locations of these sampling points.
Groundwater surface contours and elevations are shown on Figure 5 for
the condition where Well 12A and the rest of the wellfield had been shut
down for a long period of time. The flat gradient resulting in low water
velocities is indicated by the wide spacing between contour lines. The
natural flow, in the absence of wellfield pumping, is from Well 12A toward
the Time Oil site.
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t wWvjfA
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SOUTH TACOMA CHANNEL SITE
South tKonxCtonnd ROD
k
• ^'•fli rJ2>3i!
J^&ia r>fe
I Reproduced I ro m |»1
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2B
236
234.45
EXPLANATION
* El«**tion of rank «r*v torn! In
235.33 on of notcr tabl*
«h«d «tioi« Jnf-rwJ.
FIGURE 5
WATER TABLE CONTOURS
FOR 4/4/84 DATA
South T*conu Channel ROD
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TIME O»t •UtLOINOl
«•*»
70 —
~ ~38VTrK»(M)'
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SB407
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•I • IlKk fill MtMflil (horn Mil lot)I
08 • Oftf Bw^oH
58 • SMIIott Bo>thalt
GWT • Awtft litound V/|N> Intl
FIGURE 6
SECTION A-A
1.1.2. 2 TETRACHLOROETHANE 4
TETRACHLOROETHVLENE
FtbniMV 19M
(m* TMMM O>IMM| HOD
-------
M-OM
IB4KM
M-OOJ
10 —
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. ««>"
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LCGEND
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u * Uixlfliclibl*
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• • WMH Smplt u«/l
H • BlKk f ,11 MiirM (Irem tifll lo«l|
S8 • 9»lkM Rwttiol*
GWT - Amtifi Ground Wiur Lml
FIGURE 7
SECTION B-8
1.1.2. 2 TETRACHLOROETHANE
TETRACHLOnOETHVLENE
Im* T
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TIMCOtLtUllOINOS
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UH • Dno B««hol«
SB - Sirflow Sortlioli
CMT • Am««i Ciourd WK« L««l
FIGURE •
CONTAMINANT PROFILES
SECTION A-A
TRICHLOROETHYLENE
Ftbrairy 1984
^^
tw* r*
-------
10 "•
JO —
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X
8
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Dd-OOi
M-004
fx^l 160.000
Z3u.ooo
:zTr«.)«i
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Ml VihMi u«/K| uttea imtd
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• • UtKk Fill MMitM (from Mil top I
SB • Shlltow Oonhota
CWT - A«'»9» Gidund Wmr Un*
Co
FIGURE •
CONTAMINATION PROFILES
SECTION B-B
TRICHLOROETHVLENE
Fibnivy 1904
Sou* TMOIM ChMMl NOD
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14
-5-
Chemical data for 1.1,2.2-tetrachloroethane and tetrachloroethylene
taken from soil borings along the spur (Section A-A on Figure 4) and along
a North-South line (Section B-B on Figure 4) are shown in Figures 6 and
7. Data for trichloroethylene is displayed in Figures 8 and 9. These
compounds are the ones of primary interest because they are the
contaminants at Well 12A. Many others, not found at Well 12A, were also
detected at much lower concentrations.
Along the east-west lino of borings, high values of soil
contamination are located along the spur adjacent to the western Time Oil
building and continuing for a distance of at least 150 feet west of that
building. Measured concentrations of the contaminants is greater than
2.000 parts per billion (ppb) of soil to depths of about 25 feet. Highest
concentrations were found near the surface at levels up to ibout 1000
parts per million (ppm) of soil.
Along the north-south soil boring line, soil contamination
concentrations to about 3,000 ppb of soil were measured to a depth of
about 20 feet on the north end of the Fleetline property.
Continuity between this near surface soil contamination and that in
the aquifer was established. The total quantity of solvents contained in
the soil from the ground surface to the groundwater level was grossly
estimated at about 1500 Ibs.
Groundwater contamination was found along the east-west line of
borings in the same boreholes as the major soil contamination. Levels
ranged up to about 11,000 ppb of water Along the north-south line of
borings, levels up to 863,000 ppb were measured under the Fleetline
property. This southward displacement of the highest aquifer
contamination is likely to have resulted from the previous pumping action
of the wellfield.
Groundwater Contamination Migration
During Wellfield Pumping
Prior to startup of the Well 12A treatment system in July 1983, Well
12A had been shutdown since mid 1981, except for brief periods of
operation for water sampling. However, other wells in the wellfield had
been being operated on demand.
Figure 10 shows the approximate contours of I,1,2,2-tetra-
chloroethane that existed at the time of startup of the treatment system.
The highest concentrations existed near the Time Oil site with decreasing
concentrations toward the wellfield. The translation of the plume toward
operating wells (9A & 2B) can be seen on this diagram. After pumping
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15
ND
NO • Non-d«te«tablt
T- Trace
Scale: 1 Inch - 625 f««t
Reproduced from
best available copy.
FIGURE 10
CONTAMINATION PLUME
1. 1. 2, 2 TETRACHLOROETHANE
(Concentrations ppb)
July 14 to 27,1983
Before 12A Startup
South Tacom» Channel ROD
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16
-6-
began at Well 12A. the contamination levels increased at Well 12A and
decreased at the other production wells as the plume was preferentially
drawn to Well 12A. (See Figure 11.) At the end of the pumping season in
early November, the 1,1,2,2-tetrachloroethane concentration at Well 12A
was about 45 ppb, a decrease from the mid August level of about 60 ppb.
Following shutdown of the 12A treatment system in November, the plume
contours returned more nearly to their original locations, and the
concentration at Well 12A was reduced to about 5 ppb.
During the summer of 1983, the treated water from Well 12A was
suitable both for use in the City's water system or for discharge to the
bay throughout the pumping season. Observations of the plume migration
under wellfield pumping conditions indicate that effluent from the Well
12A treatment system should be suitable for discharge to the bay during
future pumping seasons. Furthermore, operation of Well 12A should
continue to block the spread of contaminants into the remainder of the
wellfield during future pumping seasons. Based on the ooserved
performance of the treatment system, the level of
1,1,2,2-tetrachlc ethane would have to average about 1000 ppb over a
pumping season brrjre the present bay discharge limit would be reached.
Observations on p.u.-ie migration during the second (1S84) pumping season
further substantiate the above conclusions.
Endangerment Assessment
Public health may be threatened either by direct contact at the
source area or by consumption of contaminate'1 drinking -water if no
additional remedial action is taken.
Taole 1 identifies the concentrations of the major contaminants at
the source and in the well water as measured during the remedial
investigation. All are known to be toxic and/or suspected carcinogens.
Direct contact, inhalation and/or ingestion of the contaminants at
the source area is one of the pathways of major concern. The railroad spur
and mainline areas are open to free access by the public. Factory workers
cross the tracks and T'me Oil property regularly, and railroad workers
must maintain the tracks and roadbed. Although litt'e data are available
on chronic dermal expo 'jre to these chemicals, an assassment was made of
possible effects for a range of exposures to the contaminated soil
assuming 25 hours a year at 10 percent absorption to 480 hours a year at
50 percent absorption. Results, presented in Table 2. indicate a cancer
risk at the 10"3 to the 10'6 level of hazard.
Consumption of contaminated wellwater is the second pathway of
exposure. Well 12A and the other wells in this system supply up to 40
percent of the City of Tacoma's peak summer demand. Approximately 214,000
people are served by City water.
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17
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'-• . * v ! • j.r ^ . » » , r * *» ' , t
) - - •>'"' \ * \ '"• ^'. :*"'< \ ^J - '
/ r •:'.'- I ; ! - ;•• ..;- • t • • f /
A*" ^ : \.^ l I/: • v ;\ *-"
NO - Nornd«tKt»blt
SeWe: 1 inch • 625 fMt
Reproduced Irom
best avaMible copy
FIGURE 11
CONTAMINATION PLUME
1.1. 2. 2 TETRACHLOROETHANE
(Concentrations ppb)
September 21,1983
~ 1X Months After 12A Startup
South Tdeomi Chtniwi ROD
-------
18
-7-
In order to assess the risk to public health from drinking
contaminated water the following assumptions were made: the well field
would be used for 90 days a year, the output o. Well 12A would not be
treated, the contamination levels observed during the 1983 pumping season
would be repeated, the Well 12A output would be thoroughly mixed with
uncontaminated water in the Hood Street Reservoir, a short term dose of
carcinogens can be averaged over the entire year, and the lifetime cancer
risk is the sum of risks associated with each chemical. Results are shown
in Table 3 and indicate that the cancer risk under these conditions would
be at the 10~s to the 1Q"S level of hazard. Actual normal use of Well
12A exceeds three months a year however, and is expected to cause the
contaminant concentration to increase at Well i2A and approach those
levels shown in Table 3 as the higher contaminant concentrations in the
aquifer are drawn in from the source area. Using the assumptions for
dillutlon in the city water system from above, this would produce a risk
level of approximately 10"".
TABLE 1
MAJOR VOLATILE ORGANICS IN SOUTH TACOMA STUDY AREA
Constituent Location
Railroad Spur Fill Well 12Aa
chlorcethane l,030.000b 61
Tetrachloroethylene 1,030,000b 1.6
Trichloroethylene 160,000 79
1,2-(Tt ans>c'ichloroethylene 3,920 30
Chloroform 0.1
a City of Tacoma data.
b Could not be differentiated.
-------
Table 2
COMPARISON OF DERMAL CONTACT AMD INGESTED CONCENTRATIONS AT THE
RAILROAD SPUR WITH RISK CRITERIA
TtlcbloroatlvltM
f«tr»chloro*thrltM
1,1-
l.l,!-l'lcblon»ttMuw
IfS-lclildlchloropropt
Oilorotirowobmtm*
1,1,1-trlctlorMlbww
J-ctilorotthrl*lnrl
Telal
HulM
Concent ration
160
1,030
Contact Chuatcal
Intake (•a/year)
For Soil Inocitrd
Contact Factor (»3/j
0.01 20 0.05
0.1 100 0.3
Equivalent
CbHilcal Tula! Intake Mater Concen*
b
«arl (§Kj/T*«r| tratlon (ppb)
1 0.07 20 0.1 30
6 0.4 100 0.6 100
Ineraaaed
Concentration Cancer
Multiplier6 Rlak <» 10 1
0.04 11
3 909
1.9
.0004 0.4 0.001 0.02 0.0001 0.4 0.001 0.< • a 10~* 1 • 10*3
3.1 0.0003 0.3 0.001 0.01 0.001 O.I 0.001 0.4
O.S 0.00005 0.05 0.0002 0.003 0.0001 0.05 0.0003 0.0?
O.S 0.00105 0.05 0.0002 0.003 0.0001 0.05 0.0003 0.07
opBotntntloa aaatun4 •Ithln 0.5 loot oC turfaoa.
bTvo 1/dar, 365 oar§/?t«r.
efciul*altat vaUr conoantratton divided br 10-d*v crlttrlot.
0.003 0.7
900
CD
-------
Table .3
COMPARISON OF WELL 12A CHEMICAL
CONCENTRATIONS TO RISK CRITERIA
Trichloroethylenc
Tetrachloroethylene
1,2-(trans)dichloroethylene
1,1,2,2,-tetrachloroethane
Total
1,1,2,2,-tetrachloroethane
Tetrachloroethylene
Trichloroethylene
Well Water
Concentrations
-------
21
-8-
ENFORCEMENT and NEGOTIATIONS
Four firms have been Identified as potentially responsible parties
(PRPs): Time Oil Company; Burlington Northern Railroad; Fleetline
Automotive; and B & W Investment (the owner of the Fleetline property).
Contaminated soil has been found on prooerty occupied by Time Oil,
Burlington, and Fleetline. All four companies have been sent CERCLA
notice letters, and information requests under section 104(e) were sent to
Time Oil and Burlington.
Negotiations were conducted with the potentially responsible parties
during the Fall of 1984. Discussions centered around the technical scope
of the proposed remedial as well as the adequacy of the RI/FS. The
negotiations were unsuccessful in concluding a consent order with the
potentially responsible parties undertaking the remedial action.
Additional discussion regarding the comments of the PRP's is available in
the Responsiveness Summary.
ALTERNATIVES EVALUATION
Objectives
The objectives of the proposed remedial action are the mitigation and
control of contamination in the groundwater and in the soil at the source
area. The requirements of CERCLA section 104, EPA's mandate to protect
the public health and welfare and the environment, determine the goals and
level of response for the site.
Alternative Screening Process
Conceptual alternatives presented in the RI/FS are listed on Table
4. These conceptual alternatives were screened in a sequential process
starting with an evaluation of each alternative with regard to technical
feasibility. Alternatives surviving tr.is screening were then evaluated
with respect to environmental effects. Comparative costs were then
developed and used to screen co'.ceptual alternatives to exclude from
further evaluation those with substantially greater costs than other
alternatives where they did not provide significantly greater levels of
protection.
-------
zz
Table 4
CONCEPTUAL ALTERNATIVES
Alternative
2. F«nce and sign cite
2. a. Cap railroad spur
b. Cap the exposed Tine Oil and
Fleetline soils
3. a. Replace spur roadbed (to 5ft 1)
b. Replace exposed Tine Oil and
Fleetline soils
4. Soil replacement below spur. Time
Oil and Fleetline property
(to 20*1 depth)
S. Deep excavation and containment or
replacement of the spur. Time Oil,
and Fleetline property (to 30ft z
depth)
€. Slurry wall around site down to
impervious strata below aquifer
7. Crour.dwater extraction well at
source with treatment before
discharge.
a Treatment at source
b Treatment at 12A off peak
1 Treatment to potable water
quality
2 Treatment to waste discharge
criteria
3 Treatment to recharge quality
criteria
8. Intermediate location collection
wells with treatment before
discharge
a Treatment at source
b Treatment at 12A off peaX
1 Treatment to potable water
quality
2 Treatment to waste discharge
criteria
3 Treatment to recharge quality
criteria
Response
Tap -Water
Protection
Objective
Surface
Contar.inaticn
Hitigatisr.
X
X
9. Continue 12A treatment system
10. In situ biological source
treatment
-------
23
Petal led Analyses
The remaining alternatives were subjected to more detailed analyses
consisting of:
o Refinement of engineering detail such as volume of soils to be
handled, excavation and shoring techniques, hauling distances,
extraction/Injection well component sizing, and modifications to the
Well 12A facilities for long-term operation.
o Cost estimates based on the limited level of detail contained in
the above engineering descriptions. Estimates considered construction
factors such as anticipated health and safety concerns, excavation,
shoring, and heavy equipment use in a constrained work area. Annual
operations, maintenance and replacement costs were also estimated
where appropriate. Estimate? were prepared for comparative purposes
and not for budget planning. Present worth calculations were made
and the total estimated present worth comparative cost for each
alternative was presented. A range of costs varying from +50 percent
to -30 percent of the calculated estimate was used for cost
comparisons reflecting the expected accuracy of these estimates at
this level of engineering detail.
o The development of engineering detail included considerations of
implementation, adverse environmental concerns, and
constructabi 1 ity. These were reflected in the cost estimates. Kno>..-n
Institutional requirements were identified separately.
o An overall evaluation of each alternative to nitigate or correct
a particular contaminant problem and a comparison between
alternatives addressing the same problem.
o Identification of combinations of alternatives that in total
were options for the full scope of required remedial action.
o A recommendation for adoption of an option which will most
reliably meet the site objectives at the estimated least cost.
The following is a discussion of the various alternatives under
consideration. The alternatives and their costs and their technical,
environmental and public health considerations are summarized in Table 5.
For purposes of this discussion, the Fleetline and Time Oil properties
including the Burlington Northern Railroad spur will be referred to as the
source area. The source area is approximately 2000 feet northeast of Well
12A. The re.nedial alternatives described below can be placed into two
general categories: (1) treatment of the contaminant plume in the portion
of the aquifer underlying the source area; and (2), treatment of the
contaminated soils in the unsaturated zone at the source area.
-------
1ABLE S
Alternatives Matrix
No Action
(Continue IRH}
Near Source
GW Extraction
Cost x $1000
Capital Present Worth
, . , , 0 t M
-0- 860
Public Health
Cons.! derations
Blocks contaminant
migration into
wellfitld. Does not
address direct contact
hazard
Does not addrpis
direct contact hazard
Environmental
Considerauons
Concedes long
term contamination
of grouitdwaler,
soils
provides some
washing of
Technical
CQQSJie callous
IRH Proven
effective in
controlling
contaminant
movement
reliable, proven
technology
Public
torment
not acceptable
by itself
Other
Cflcpeau
IRM will continue
and will be part of
alternative selected
Institutional
requirements
creates acceptable
air emission.
Aeration treatment
A. Treat to level 540
allowing direct
discharge of Well 12A
and/or treatment
of Wei1 12A to 10's
•;Undard
B. Treat to level 540
allowing use of Well
12A without treatment
factoring in
dillutton in DW
system
C. Treat to level 540
allowing use of
Well 12A without
treatment
534
592
951
Can provide DW
to lO-& Standard
at the tap
can provide DM
at 10'6 standard
at the tap
provides 10"6 OW
throughout DW system
contaminated soil
Concedes long
term GW
coi' imination at
reduced level
concedes long
term GW
contamination at
reduced level
Reduces GW
contamination
to 10"6 level
within wellfield
acceptable as
component of
final RA
occcptable as
component of
finil RA
acceptable as
component of
final RA
institutional
controls
long term
use of IRH.
operation of DM
system to provide
dillution (2lx)
Iciig term
operation of
extraction well.
D. Treat GW to
10"* DW standards
at hazardous waste
sile boundaries
540
1230
provides 10 DW
throughout aquifer
reduces GW
contamination
throughout
aquifer
reluctance by
agencies
providing O&H
Long term operation
of extraction well
-------
1/iBLl 'j (continued)
Cost x $1000
Capital Present Worth Public Health
Alternative 0 & H Considerations
Cap portions 50 Eliminate direct
of Time Oil contact
SPUR Removal, soil '
excavation, off
site disposal
Excavation
A. To Five Feet 1.000 -0-
B. To Twenty Feet 2.500 -0-
C. To GW Table 14.500 1.500 r
Removal of all
coi.timinated soi"
within boundaries
on site disposal
In lined excavation
Environmental
Considerations
Removes and
secures
contaminated
material
Removes most
highly
contaminated
material
Removes more
contamination
than shallow
excavation
isolates all
contaminants
from soil
Technical Public Other
Considerations Comment Comments
simple acceptable
technology
simple acceptable transfers contamln-
constructlon ants to secure
technology location
removes soil acceptable
which would
resist treatment
can be acceptable
accomplished but
requires extensive
Shoring fill.
difficult on site
excavations, disposal lower cost
demolition than removal
ca
-------
26
10
No Action Alternative
The No Action alternative would involve no further action by EPA.
The IRM previously implemented would be continued in order to provide the
treatment to the Well 12A effluent to allow its use in the drinking water
system or discharge to Commencement Bay. The cost of the O&M for the
treatment of Well 12A would be the responsibility of the State of
Washington. This alternative does nothing to mitigate soil contamination
and little to mitigate groundwater contamination, but operation of Well
12A Is necessary to prevent the further spread of the contaminant plume
Into the municipal wellfield. Very long term operation of Well 12A (in
excess of 100 years) may eventually flush the aquifer and the contaminant
plume at the source to the point where the untraated effluent from Well
12A. when mixed and diluted in the City water system, could provide the
10"' level of hazard at the tap. However, it is likely that as the
heavily contaminated plume is drawn towards Well 12A, the levels of
contamination at the well would exceed the capacity of the present
treatment system. This would result in the inability to use the treated
groundwater in the city drinking water system unless the treatment system
1s upgraded.
The No Action alternative does not alleviate the possibility of
direct exposure at the source area. The public would still be able to
ma^e direct contact with, ingest, or inhale dust or vapors from the
contaminated soils at the railroad spur and other locations on the Time
Oil property. Further, the No Action alternative would leave open the
possibility that users of the city watar system would be exposed to water
at the 10"" risk level as the higher levels of contamination now in the
source area are drawn towards Well 12A and the wellfield.
Groundwater Treatment at the Source
The proposed treatment of the groundwater at the source would be in
conjunction with the continued operation of the 12A treatment system (the
IRM). The contaminated groundwater would be drawn from the aquifer
through extraction wells 'located at the source, treated by a single pass
through an air stripping tower, possibly followed by carbon adsorption,
and discharged to surface waters. A portion of the treated water would be
directed to a drainfield consisting of perforated pipe set at a shallow
depth. The purpose of the drainfield would be to flush or leach
contaminants remaining in the soil matrix (below the excavated zone) to
the groundwater where they would be collected. The system would be
operated until the accepted level of treatment is reached. Extraction and
treatment of groundwater at the source should offer significant reductions
in the treatment duration that would be required if the groundwater were
treated at Well 12A only, as described in the No Action Alternative.
-------
11
Reinjection of the treated water was discussed in the RI/FS but has
been set aside in lieu of surface discharge. The costs are equivalent.
Surface discharge should, however, allow for a more rapid treatment of the
contaminated aquifer.
Aeration treatment of the extracted groundwater will result in the
emission of volatile organic solvents from the system. The estimated
amount, based upon the groundwater concentration and removal efficiency,
is 200 pounds per day for the initial weeks of operation. The amount would
steadily decrease as treatment of the aquifer is achieved. By comparison,
the Well 12A IRM releases less than 40 pounds per day. Under the worst
case conditions, the concentrations of solvents occurring a short distance
downwind from the source extraction system would be less than one percent
of the allowable concentration set by OSHA for an 8 hour occupational
workplace exposure.
As presented in the RI/FS, the principal contaminants found in the
aquifer, are: tricnloroethylene, tetrachloroethylene, l,2-(trans)
dichloroethylene and 1,1,2,2- terrachloroethane. Of these, based on water
quality criteria for human consumption of drinking water,
1,1,2,2-tetrachloroethane provides the greatest risk as a carcinogen for
any given level of exposure. Furthermore, 1,1,2,2-tetrachloroethane is
the most resistant to treatment by air stripping. Therefore the design of
any treatment system would be based upon 1,1,2,2- tetrachloroethane.
For purposes of assessment of the probable cost of groundwater
treatment, several approaches for determining the extent of groundwater
treatment were evaluated. Io this assessment, the 10"s risk level was
used to represent the level of exposure which would provide adequate
protection, and the alternatives differed based upon the degree to which
long term protection would be provided by treatment of the plume at the
source, as opposed to reliance upon other methoas, such as institutional
controls upon groundwater use. The alternatives assessed are nested in
such a way that when the selected level o.c treatment is achieved, the
lesser levels of treatment are also achieved in the interim. Thus when
the groundwater extraction system is operated, it will proceed
sequentially through the various levels, in effect shrinking the areal
extent of the contaminant plume. The alternatives are presented for
purposes of discussion of the range of costs and treatment levels
available.
A. Treat the groundwater anc! establish a level such that
the effluent from Well 12A could be discharged untreated
to the bay or with treatment, the 12A effluent could
be utilized in tha City water supply after dilution
with other waters. This option 's the least rigorous
and is similar to the preferred option in the RI/FS.
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28
12
An institutional control in the form of deed restrictions
would be necessary to prevent installation of any
wells between the source and Well 12A. The concentration
of 1,1,2,2-tetrachloroethane would be approximately 20
ppb in the Well 12A effluent . It is estimated that
with a 200 gpm extraction rate at the source, a 20 ppb
level could be achieved at 12A in approximately one
year.
B. Treat the groundwater and establish a level such that
the untreated effluent from Well 12A could be used
(after 24:1 dilution in the City system) as drinking
water. This option would provide 10~b level of
hazard at the tap. Institutional control similar to
(A) is required. The concentration beneath the source
would be approximately 2000 ppb and about 2 ppb at Well
12A. These levels might be achieved in one to two
years if 200 gpm is extracted at the sou-ce.
C. Treat the groundwater and establish a level such that
the Well 12A effluent would be at the 10~6 level of
hazard, with no dilution. Institutional control is required.
At the source, the 1,1.2,2 concentration would be approximately
85 ppb and at Well 12A, the concentration would be 0.1 ppb. The
estimated treatment duration is 2 to 10 years at 200 gpm.
D. Treat to a level such that the groundwater at the source
(within the property boundary) is at the 10"6 level
of hazard. This option provides the greatest
environmental protection in the sense that no portion
of the aquifer (outside of the property boundary) is
written off. A temporary (probably 20+ years)
institutional control would be required between the
source area and Well 12A until the plume outside the
source area is treated to the 10"s level of hazard.
Treatment to *his level could take anywhere from 30 to
?00 plus years at 200 gpm.
The alternatives just presented all use the same treatment technology
but vary in the duration of treatment (and hence, the cost of treatment)
Alternatives A. B and C all require permanent institutional control of
groundwater use. Alternative D would require an institutional control
during the many years it will take before the plume outside of the source
area is treated. The controls would prevent the use of contaminated
water, protecting public health, and would assure that any extractions or
injections into the groundwater would not Interfere with the remedial
treatment system. Institutional controls could be accompliched by the
State of Washington through the control of water rights.
-------
Table 6
Groundwater Extraction/Treatment Costs
K $
200 gpm
A
B
C
0
400 gpm
A
B
C
Capital
540
540
540
540
620
620
620
0 & M
Low
65
65
(1 yr)
118
(2 yr)
613
(30 yr)
74
74
74
(1 yr)
High
118
(2 yr)
436
(10 yr)
650
(200+ yr)
74
295
(5 yr)
(Salvage)/
Replacement
(71)
(71)
(66)
24
(82)
(82)
(82)
(66)
(25)
48
(82)
(59)
Total
Low
534
534
592
1,177
612
612
512
Cost
High
592
951
1,238
612
856
620 633 925 28 1,253 M73
H5 yr) (200+ yr)
All Costs Present Worth
-------
30
13
The costs for the various alternatives are presented on Table 6.
Present worth costs for the 200 gpm system range from $605,000 for
alternative A to $1,190,000 for alternative D. Treatment durations and
costs are also provided for a 400 gpm system for purposes of comparison.
The high and low cost ranges are dependent upon assumptions of soil
characteristics. A system with larger extraction capacity would
accelerate groundwater treatment with an increase in capital and 0 & M
cost. System size can be optimized during preliminary design.
Treatment and Disposal of Contaminated Soil
In the RI/FS, two areas of contaminated soil were Identified; the
soil under the railroad spur and soils elsewhere on the Time Oil and
Fleetline properties. The principal soil contamination occurs in the
uppermost soils under and adjacent to the railroad spur. Here, the
contaminant concentrations generally decrease with depth. In the soils
underlying the other properties, low levels (hundreds of ppb> are found
throughout the soil column.
One purpose of treating or disposing of the contaminated soils 1s to
eliminate the possibility of direct public exposure to the soils. A
second purpose is to eliminate the possibility of long term leaching of
contaminants into the groundwater. Quantitative analysis of the effects
of long term leaching on the duration of groundwater treatment has not yet
been conducted. However, the length of treatment of the aquifer would
clearly depend on the degree to which the overlying soils continue to
leach contamination to the groundwater. Limited soil excavation can
remove most of the estimated solvent contamination in the soil and reduce
the solvent available to the aquifer.
Three approaches were evaluated for the purpose of eliminating the
risk of public exposure to the soils and reducing the potential for
further contamination of the aquifer. The first is excavation and removal
to either a RCRA landfill or a secured location on site. The second is
treatment by flushing until contaminant concentrations in the soil and
underlying groundwater reach a yet to be established level consistent with
the situation surrounding the site. Third, the contaminated soil could be
capped and surrounded by monitoring wells in a manner consistent with RCRA
site closure procedures.
Specific alternatives considered include leaving contaminated soils
in place and capping, excavation and disposal off-site of the uppermost 5
feet, excavation and disposal of the uppermost 20 feet of soil.;, and
excavation to the water table (a depth of 30 feet) with on-site disposal
in a lined facility. Present worth costs and relevant comments are
presented on Table 5.
-------
31
14
One approach considered was to demolish the structures and excavate
all soils over the full extent of the Time Oil and Fleetline properties
and the Burlington Northern spur to a depth of 30 feet (approximately the
depth to the groundwater table.) The excavated soil would De disposed of
either in a RCRA permitted facility off-site or in an on-site facility.
On site disposal would be less expensive in this case. However, on-site
disposal was rejected because of limited space which would affect
construction activities. In addition, the cost of on-site disposal, while
less than that of off-site disposal, is extremely high for the deep
excavation option.
Capping of all of the contaminated soil in place was evaluated and
rejected. Surface land uses prevent construction of the surface cap
laterally beyond the edges of the contaminated soil tr an extent
sufficient to guarantee that infiltrating precipitation might not move
laterally into contact with the contaminated so'is. Therefore, the
possibility exists that long-term intermittent leaching of the
contaminated soil may occur. Furthermore, the presence and continued use
of the railroad spur would make it difficult to construct and maintain an
effective cap, providing further potential for leaching.
Treatment of all of the contaminated soil by flushing with no
excavation was also evaluated. The uppermost 5 feet of soils under and
adjacent to a portion of the spur are contaminated with an oily, fine
grained filter cake which resulted from oil recycling operations on the
site. This material, which is '-isually identifiable by its dark color,
contains high concentrations of organic solvents. Because of its oily,
fine grained (clay-like) nature, this material is expected to resist
cleansing by flushing.
Because treatment by flushing is considered to be effective for some
but not for all of the contaminated soils, the alternative of removal of a
portion of the soils and flushing of the remainder was evaluated. The
discolored (oily, fine-grained) soils and filter cake under and adjacent
to the railroad spur, plus one foot, are to be excavated and disposed of
off-site. The rationale for removing these materials is that flushing of
the underlying soils is planned, and it does not appear that these oily,
fine-grained materials would submit well to that form of treatment.
Certain soil test borings (SB-003 and DB-005) indicate the presence of
high solvent concentrations below the discolored zone. Additional
excavation would then be conducted in those areas where small incremental
increases in soil excavation would then produce relatively larger
increases in solvent removal. Removal of the additional material would
increase the reliability of soil flushing and would reduce the time of
treatment to achieve any given level of cleanup. Depths of soil
excavation will be based on soil test borings and be approximately 5 to 6
-------
32
15
feet along much of the railroad spur and possibly up to 12 feet near soil
borings DB-005 and SB-003. The piping for the soil flushing system will
be installed in excavated areas. Permeable backfill will be placed to
protect the piping and to prevent direct human contact with the underlying
soils during the flushing process.
An alternative to leaching the contamination from the soil with water
would be the use of in-situ soil aeration to remove the volatile
contaminants. The site specific feasibility of this alternative will be
evaluated when data from additional soil borings is obtained.
As mentioned, the soils elsewhere on the Time Oil and Fleetline
properties have low concentrations of contaminants distributed throughout
the soil column. It is proposed that these soi's be left in place and
covered and that they later be addressed in a manner consistent with those
at the railroad spur when the close-out requirements are determined.
Additional borings are planned during the design phase. Should pockets of
highly contaminated soils be found at depth in other areas of the site
they would be dealt with in a manner similar to the soils at the railroad
spur.
The decision regarding the final cover or capping of the site would
be made at the point when the endpoint level of groundwater treatment is
established. The need for and design of the cover would be based on any
residual soil contamination.
Summary of Recommended Option
The recommended option contains the following elements:
At the railroad spur and the adjacent areas of the parking lot.
excavation will be performed for the visually contaminated soils plus one
additional foot. There will also be additional soil excavation in areas
where high levels of contamination are found.
It is intended that soil flushing at the spur will continue until the
remaining contaminants pose no further threat to the groundwater and
therefore, it will not be necessary to cap the site. However, no
recommendation is made at this time as to the soil contaminant
concentration which will achieve this goal. The soil cleanup level will
be addressed in a later decision.
Limited excavation of the visually contaminated materials is
recommended because of the resistance of such materials to treatment by
flushing. Excavation of small amounts of additional highly contaminated
soil is based upon the enhanced reliability of the soil flushing system
and the fact that excavation of these soils is expected to reduce the
period during which'the soil flushing and the groundwater treatment system
must be operated to reach a given level of cleanup.
-------
16
Lesser contaminated soils of the site will be paved or covered with
uncontamlnated soil as an interim remedy to prevent direct contact with
the contaminated soils. A determination of whether additional steps may
need to be undertaken as a permanent remedy for these areas will be made
in conjunction with the determination of an appropriate cleanup level for
the areas to be treated by flushing.
The recommended remedy includes the construction of a groundwater
treatment system consisting of an extraction well(s) at the source area,
treatment of the extracted water by aeration and the discharge of the
treated water to Commencement Bay. Although the appropriate level of
groundwater treatment has not been determined at this time, EPA believes
chat the installation of such a treatment system at the Site is cost
effective and necessary to protect health and the environment for several
reasons: operation of the groundwater system is necessary to eliminate a
large amount of heavily contaminated groundwater near the site and beyond;
operation of the system is also expected to substantially reduce the
period of time during which the treatment system at Well 12A will need to
be operated; and the treated water is an integral part of the soil
flushing remedy.
The appropriate final groundwater treatment level will be determined
as additional information is gained through operation of the system.
Based upon present data, the recommended remedy does not include
carbon adsorption treatment of the solvents released from the aeration
treatment. The release of solvents in the quantities expected wili not
pose a threat to health or the environment. Should it be determined that
the release will be inconsistent with the protection of health or the
environment, the Regional Administrator shall have the authority to
approve modifications to the system and/or its operations, including
carbon adsorption, to mitigate any threat.
The Regional Administrator shall also have the authority to approve
changes in the treatment of on-site soils to other methods, including soil
aeration, which are found to be equivalent in cost and effectiveness of
the method, -toe feasibility of other treatment methods may be evaluated
during the design of the remedial action.
--CONSISTENCY WITH OTHER ENVIRONMENTAL LAWS
All facets of the proposed action will be consistent with with the
technical requirements of other environmental laws. The off-site
transportation and disposal of contaminated soils will be in accordance
with appropriate Resource Conservation and Recovery Act (RCRA)
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regulations. Including manifesting of wastes and shipment to a RCRA
approved facility. No determination has been made as to whether the
material excavated will be disposed of in a single or double lined
facility. Operation of aeration towers for the treatment of contaminated
g>xundwater will be conducted consistent with the appropriate Clean Air
Act regulations for emissions of volatile organics into the air. The
discharge of treated groundwater to navigable waters will be consistent
with the Clean Water Act.
Safe Drinking Water Act—There are no drinking water standards for
the contaminants present at Well 12A. Groundwater from n'ell 12A, Intended
to be used as drinking water, wi i 1 continue to be treated to the 10~6
risk level for the contaminants present.
Clean Air Act—The Puget Sound Air Pollution Control Agency (PSAPCA)
controls air discharges. A permit has been issued for the Well 12A
treatment facilities. PSAPCA must be notified of any changes to the
facility or operating conditions thai would increase the discharge. The
air stripping towers at the extraction well (at the source) will meet all
technical requirements for an air discharqe.
RCRA- The decisions regarding closure of the site and the level of
groundwater quality to be achieved are deferred. In order to be
consistent with 40 CFR 264 Subpart F of the regulations, groundwater
corrective action is required until the concentration of hazardous
constituents at the point of compliance for a site achieves one of the
following: Maximum Concentration Limits (MCL), where designated for
particular substances; an Alternate Concentration Limit (ACL), which would
provide adequate protection of public health and the environment; or
background levels.
EPA is not prepared at this time to determine the appropriate level
of grcurdmater corrective action at this site. Operation of the
groundwater treatment system for two years will substantially reduce the
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amount of contaminants in the groundwater in the vicinity of the source
and would reduce the plume of contaminated groundwatei which exceeds the
10"s risk level previously established for Well 12A. Using data and
information collected in that period, EPA would make a determination as to
the level of contaminants which would adequately protect health and the
environment. Under CERCLA, the groundwater treatment system would be
operated until this level of treatment is achieved unless that level
proved technically infeasible or placed an unreasonable burden upon the
Fund.
Where RCRA closure regulations are applicable, they would require
that all hazardous wastes at a site be removed, treated on site or capped
In such a way as to minimize the migration of contaminants from the site.
At this site, certain oily and other heavily contaminated soils would be
excavated, transported and disposed of offsite in accordance with RCRA
regulations. Other contaminated soils underlying the excavated areas
would be treated by flushing. While the areas would not be capped
Immediately In accordance with RCRA, the backfill, paving and cover in
other areas should adequately address direct human exposure during
treatment.
In conjunction with the establishment of a grcundwater treatment
level, EPA would evaluate the level of contaminant1; which could be left in
the soil without the necessity of a cap at the sit?.
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OPERATIONS AND MAINTENANCE (O&M)
Activities
Near Source Extraction System and Hell 12A System
o Dally equipment flow, pr-.ssure, temperature logging,
and general equipment observation.
o Weekly inlet/outlet water sampling and analysis for
VOC's.
o Annual fan and pump maintenance inspection per manu-
facturers' instructions.
o For 12A system only, periodic packing chlorination, and
seasonal shutdown and startup procedures.
Monitoring Nells
o Approximately monthly sarr.pl ir.g and analyses for VOC's.
Surface Cap
o Monthly inspection and repaving as necessary
Reporting
o Approximately bimonthly consolidation and reporting of
12A, near source, and monitoring well data.
Future Actions
As outlined under O&M:
• o Operate and maintain near so rce extraction system year
round.
o Operate and maintain Well 12A facility. Estimated four
months a year operation.
o Sample and analyze existing monitoring wells, evaluate
and report progress of cleanup.
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SCHEDULE
Approve Remedial Action 9/84
Initiate Negotiation with PRPs 9/84
Negotiation Successful
Sign EDO, Consent 106 AO 3/85
Negotiation Unsuccessful
Unilateral 106 AO effective
Sign ROD. IAG
Design Initiated by PRPs
2/85
2/85
Design Initiated by EPA
Construction Procurement
by PRPs
5/85
9/85
Construction Procurement
by EPA
Construction Initiated
by PRPs
7/85
Construction Completed
by PRPs
10/85
Construction Initiated
by EPA
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RESPONSIVENESS SUMMARY
SOUTH TACOMA CHANNEL SITE
(PUBLIC WELL 12A)
REMEDIAL INVESTIGATION/FEASIBILITY STUDY
Part I
Introduction and Overview of the Public Meeting
A public meeting was held at the Tacoma-Pierce County Health
Department auditorium on July 25. 1984, to discuss the Remedial
Investigation/Feasibility Study (RI/FS) report for the South Tacoma
C^.annel Site (Public Well 12A) and to accept public comment. The meeting,
which was attended by approximately 20 persons, started at 7:00 p.m. and
ended at 7:45 p.m.
A press release was issued in late June to announce the public
meeting. A fact sheet summarizing the RI/FS report was mailed to more
than 300 Individuals and organizations in late June. The RI/FS report was
available for public review at the Tacoma Public Library, Tacoma-Pierce
County Health Department, and Tacoma Department of Public Utilities. The
public meeting was well covered by the media.
The meeting was chaired by Philip Wong, Site Manager for the
project. He was assisted by Dr. Chuck Shenk from EPA's Superfund Program,
and by Bob Schilling from CH2M HILL, the project consultant.
Mr. Wong briefly described the site history, the nature of the
problem, the initial remedial measure conducted in 1983, the cleanup
options that were considered, and the recommended alternative. He then
called for questions and comments from the audience.
Five speakers offered questions or comments. The questions generally
asked for clarification of various aspects of the cleanup options and the
recommended alternative. The Washington Department of Ecology stated its
support for the recommended alternative which included shallow excavatyion
of the soil at the spur and other areas of the site and the extraction and
treatment of the groundwater beneath the site. Mr. Wong stated that EPA
has also received endorsement from the City of Tacoma Water Department and
the Tacoma-Pierce County Health Department. All three agencies recommend
implementation to occur as soon as possible.
Mr. Wong announced that the public comment period is open until
August 1, 1984, and that EPA encourages written comments. All comments
will be considered in the decision process, and a written response to the
comments will be included in the Record of Decision. According to the
current project schedule, final project approval will occur in September
1984 and design will begin soon after that. Project implementation is
projected to begin in Spring 1985.
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The following is a summary of the questions and comments made during
the public meeting. The paraphrased responses to those questions and
comments are included. In addition, further responses to several of the
questions are provided in Part II of this summary.
Summary of Public Comment and Agency Response During the Public Meeting
1. Comment/Question: Why are Options 1 and 2 so close in cost.
although Option 1 does so much more?
Response: Under Option 1, the extraction facility and the
Well 12A air stripping towers could probably be shut down
after five years of operation. Under Option 2, the Well
12A stripping towers would have to operate for as long as
100 years to remove the contamination. The present worth
cost of Option 2 results from the operation and maintenance
costs associated with operating the stripping towers over a
long period.
2. Comment/Question: A representative of the Washington
Department of Ecology (DOE) stated DOE's support of Option
1 and requested EPA to proceed rapidly toward the detailed
design of that option. DOE believes the pumping/treatment
system should be the first step, followed by detailed evalu-
ation of the soil contaminants.
3. Comment/Question: Mr. Wong stated tnat EPA has also received
endorsement of Option 1 from the City of Tacoma Water Depart-
ment and the Tacoma-Pierce County Health Department. These
agencies recommend that implementation occur as soon as
possible.
4. Comment/Question: Where did the contaminated fill material
along the railroad line originally come from? Is it possible
that the same material was used at other sites where a
similar problem could arise in the future?
Response: The fill matei ial was probably not imported; it
was contaminated in place. It is very difficult to track
it because it could have been put there decades ago. The
National Oil Company operated on that site and deposited
sediments there for a number of years. At some point,
solvents got mixed in with those sediments; they were either
a part of a grossly contaminated batch of used oil or v."»re
dumped on top of the oil sediments to dispose of them. The
National Oil Co. stored a lot of solvents on site. That may
be how much of the ground on adjacent facilities, as well
as along the railroad tracks, became contaminated. But at
this point, it is speculation because it happened so long
ago.
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5- Comment/Question: Is all the work for this site funded with
Superfund money? And who makes the final decision about
which option is selected?
Response: So far, all funding has been Superfund money,
with the state paying 10 percent for the cost of the towers.
At this point, additional work will also be funded by Super-
fund, pending any kind of negotiated settlement with the
responsible parties.
EPA. in conjunction with the state and local agencies that
are involved, will decide which option is selected. So
far, there seems to be agreement that Option 1, that is. shal'ow
soil removal and groundwater extraction and treatment, is the best
alternative. EPA will further consider the options follow-
ing the public meeting anc! the comments received from the
public and involved agencies.
6. Comment/Question: Is there any other option for providing
a water supply, such as closing these wells and drilling
someplace else at a lesser cost?
Response: The problem is that it is not just a matter of
_. abandoning only Well 12A or Well 9A. When 12A was shut down,
9A became contaminated; when 9A was shut down, •.'lere was
evidence of contamination moving toward Wells 2A and 11A.
This could occur all the way down the well field. To abandon
the entire well field and drill again would be a much more
expensive, and not necessarily reliable, option. The well
field provides up to 40 percent of the city's water during
the summer. No more water can be taken out of the Green
River. The city has been drilling test wells to look for
other sources of water for the past few years, but has
found nothing that could provide as much water as is needt-d.
7. Question/Comment: What volume of airborne pollution would
result from using the new stripping tower to clean the
ground water?
Response: About 40 Ibs. a day of solvents are released into
the atmosphere from the existing Well 12A stripping towers.
That is equivalent to the amount of solvents released into
the air by two gas stations. The stripping towers operate
only during the summer, while gas stations operate year-round,
so the towers are a minor contamination source. Under worst-
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case conditions, the concentration of solvents occurring a
short distance downwind from the towers would be only one
ten-thousandth of the concentration allowed by OSHA for
8-hour occupational work. The stripping towers have an
operating permit from the Air Pollution Control Authority.
The new stripping tower would be smaller and would have much
more concentrated material coming into it than the 12A
towers. It would release about 200 Ibs. of solvents per
day into the atmosphere for the first few weeks. Within
six months, the amount would be equivalent to 12A, and then
would continue to decrease as the groundwater is cleaned up
through the stripping process.
8. Comment/Question: Is it correct that the contamination that
goes into the air will eventually come back down into the
water supply again, only not in a dangerous concentration?
Response: It does come back down to the ground in a widely
dispersed form. Fortunately, it naturally deteriorates, so
when it is exposed to air and sunlight, the solvent disinte-
grates.
9. Question/Comment: What was the initial reason for EPA's
involvement at this site? Were specific illnesses reported?
If not, why is EPA proceeding if there is no evidence that
anyone, is actually being harmed?
Response: EPA undertook a national sampling program of
public drinking water wells in 198!. Either the health
department or the state recommended that EPA look at this
site because it was in a high.ly industrialized area and
there was some concern about nearby firms. Testing in 1981
revealed high levels of contamination.
There is no evidence at this time that people in this area
have suffered ill effects from the drinking water. However,
two of the contaminants are known carcinogens. The main
contaminant, 1,1,2,2-tetrachloroethane, is the most toxic
chlorinated solvent and has been banned from many countries
because of its extreme toxicity. We know that it causes
liver damage and other acute effects if people are exposed
to massive doses of it. However, it is difficult to know
the problems that would result from drinking small amounts
of it over a long period of time. We have the same problem
with most of the chemicals we deal with. No studies have
bean done on people, and we have to extrapolate from studies
jn 1.coratory animals. We are uncertain at this time how
much effect these contaminants may possibly have had on
people in this area.
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The State of Washington and the local health department have
established what Is called a 10-6 risk level for these con-
taminants. Based on the Information we currently have,
this means that if 1,000.000 people were to drink two liters
a day of water that contains this evel of contaminant, one
person would contract cancer from this exposure. That is
the level we are cleaning the warer up to, as set for us by
both the state and the county.
10. Question/CoTiment: What are the criteria for removing the
contaminated soil? How did you arbitrarily pick an excav-
ation depth of 5 feet?
Response: We picked a depth that would remove most of the
contaminated railbed material. Five feet was used as a basis
for estimating comparative costs. We recommend that for
the conceptual design, excavation depth is based on reducing
the contamination to a certain level. We want to mitigate
the hazard to people that might result from direct contact
with or inhalation of contaminants. Air monitoring at the
site has shown no problem with air contamination. However,
direct contact is a hazard because tetrachloroethane can be
absorbed through the skin. The material is highly contamin-
ated; some of it has been about 3 percent tetrachloroethane,
which is a large amount. We are also concerned that if it
is allowed to remain there, it could filter down to the
groundwater and be a continual contamination source.
11. Comment/Question: I~ the tetrachloroethane can leach through
the soil into the groundwatei, couldn't it then be treated
through air stripping? Only 600 Ib of contaminants have
been identified from this source, versus 10,000 Ib already
in the groundwater. I suggest this as an alternative because
removal of the soil is estimated to cost $500 per cubic yard.
Response: We want to make sure we get rid of the '.
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Response: It is possible that additional information will
be needed during the soil removal to ensure that all contam-
inated areas have been reached. We do feel, however, that
our data from the monitoring wells has pretty well defined
the contaminated area, and that the source does not extend
much further. We did take some surface samples from the
other side of the tracks and around the areas that were
most contaminated, and found no evidence of anything there.
Conclusions About the Meeting
The questions asked at the meeting generally requested clarification
of various aspects of the cleanup options and the recommended
alternative. The Washington Department of Ecology, City of Tacoma Water
Department, and Tacoma-Pierce County Health Department support Option 1,
the recommended alternative and urged implementation as quickly as
possible.
Part II
Supplementary Responses to Comments Received at the Public Meeting
EPA has reviewed the comments raised at the public meeting, and the
responses made at that time. Based on that review, and with knowledge of
the final remedy recommended for this site, EPA believes it would be
useful to expand upon or clarify serveral of the responses presented at
the public meeting.
Comment/Qusstion 9
For the on-going treatment of the water pumped from Well 12A, EPA and the
State of Washington selecten the 10"s risk level as the appropriate
criteria to assure that users of the well were adequately protected.
For this remedial action, EPA has not selected a cleanup endpoint for
contaminated grountiwater at the source area. EPA will initiate a
groundwater pumping and treatment program, and will select a concentration
limit which will provide adequate protection of human health and the
enviornment, considering the particular factors associated with this
site. The choice of a treatment level will be based in part on experience
with the first two years of operation of the groundwater treatment and
soil flushing system.
Question/Comment 10
The decision to excavate contaminated soil was initially based on the fact
that it would be very difficult to flush the solvents from the oiry-soils
near the surface. For this reason, EPA selected its soil cleanup criteria
based on the presence of soilt: which were visibly contaminated with oily
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7
materials. It is believed that removal of such visibly contaminated
material would allow the soil flushing to be carried out successfully.
For the purposes of estimating costs, the 5 foot level was used to
represent the approximate lower bound of the visibly contaminated soil.
EPA has also determined that some soil immediately below the visibly
contaminated zone generally contains a relatively high concentration of
solvents. Althougn it is difficult to precisely predict the effect of
removal of this additional material, EPA believes that excavation of an
additional one foot (approximately) of the most heavily contaminated soil
will increase the reliability of the groundwater treatment/soil flushing
system, and reduce the amount of time that the system must be operated to
reach any given level of protection for soil and groundwater. In
addition, as .was discussed at the meeting, excavation of surface material
will prevent direct contact with contaminated material
Comment/Question 11
EPA is excavating and removing only the visibly contaminated soil, which
would resist flushing, and a small additional amount of the rrost hpavily
contaminated material. The bulk of the contaminated soil will be
addressed by flushing the contaminants into the groundwater, which will be
pumped and air-stripped to remove the contaminants.
Part III
Post Meeting Written Comments
In addition to the comments received at the meeting, written comments were
received from three agencies and two private companies. As noted earlier,
the Washington Department of Ecology (WDOE), the City of Tacoma Public
Utilities Department and the Tacoma Pierce County Health Department all
urged that the selncted remedial action be implemented as quickly as
possible. The Public Utilities Department also emphasized the importance
of the aquifer to the City as a part cf their future water supply base.
The WDOE submitted a number of comments concerning continued operation of
Well 12A, the proposed water treatment system at the source, cleanup and
construction at the site, review of site history, monitoring and
modeling. Several of the Department's comments have already been
considered by EPA. Many of the other comments will be addressed during
the design phase of the project. In addition, EPA will involve the Tacoma
Utilities Department, the Tacoma Pierce County Health Department and the
Washington Department of Social and Health Services in these discussions.
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Two of the identified potentially responsible parties requested a 60
day extension to the public comment period. EPA did not extend the
comment period but agreed to allow the parties additional time to respond
to the RI/FS in conjunction with the negotiation process provided specific
conditions and deadlines would be met. Copies of the requests and EPA's
responses are attached.
Time Oil responded to the RI/FS by questioning the validity of
assumptions used in modeling groundwater behavior and finding fault in the
basic interpretation of data. Time Oil concludes that insufficient data
has been produced to declare their property as a major source of
contamination of Well 12A and that insufficient work, has been conducted to
locate all potential sources.
EPA has responded by pointing out that modeling was used as a
supplementary tool of investigation and that the same conclusions would be.
reached from direct observation of the data. EPA maintains that the data
clearly identifies the Time Oil properly as a major source of
contamination and that it does not indicate any major source beyond the
Time 01 I/Burlington Northern site.
Burlington Northern has questioned the sufficiency of data, the cost
effectiveness and cost estimates of EPA's proposal and states that the
Burlington Northern property is not a contaminant source and that the
company is not a responsible party under CERCLA.
EPA has responded in pointing out that the data clearly demonstrates
that Burlington Northern property contributes contaminants to the
groundwater beneath the site. Many options were evaluated and developed.
The selected alterative is one which adequately meets the criteria and
goals of remediation for the source area.
The PRPs, especially Time Oil Company, and their consultants have
provided EPA with a number of documents presenting proposals and
critiquing the RI/FS. Some of the principal documents and responses from
EPA contractors are listed below and are attached as part of the
Responsiveness Summary:
Report entitled , "Evaluation of Studies Conducted for U.S. EPA on
South Tacoma Channel, Tacoma, Washington. Part I of Two Parts, dated
August 31, 1984. by Cor Star, Inc.
Report entitled , "Evaluation of the Groundwater Flow System in the
South Tacoma Channel Area, Tacoma, Washington. Part II of Two Parts,
dated September 14. 1984, by Cor-Star, Inc.
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Letter, dated October 30, 1984, from John Varnum (Time Oil's counsel)
to Chuck Shenk (EPA-X).
Letter, dated November, 6. 1984 from Charles Flndley (EPA Region 10)
to each of the PRPs.
Memorandum, dated November 28, 1984. from John Varnum (Time Oil's
counsel) to EPA Region 10 responding to the November 6, 1S84, letter.
Petition, dated November 28, 1984, from John Varnum (Time Oil's
counsel) to William Ruckelshaus (EPA-HQ) with attachments, requesting
modification of the NPL listing of the Tacoma Well 12A site.
Letter, dated January 4, 1985, from CHZH Hill to Phil Wong (EPA
Region 10) addressing contents of PRP materials and reports.
Letter, dated February 13, 1985. from CH2M Hill to Phil Wong
further addressing the PRP materials.
During the course of the negotiations conducted during the Fall, 1984. the
PRPs raised a number of technical points regarding the results presented
in the RI/FS, especially the description of the site-specific
geohydrology. The detailed technical arguments are found in the
previou: "y listed reports, letters and memorandums, and a brief summary is
provided below.
The PRPs have argued that the site (Time Oil and Fleetline
properties) could not possibly be the source of contamination at Well 12A
because a groundwater divide forms between the site and Well 12A when the
well field is pumped. Their contention that the groundwater divide forms
is based principally on the results of a groundwater modeling effort
prepared by their consultants. They further question certain aspects of
the set-up, calibration and operation of EPA's model (which does not show
the presence of a divide). EPA's consultant has re-examined the data and
use of the model and has responded that EPA did not rely heavily on a
model at this stage of the investigation, and furthermore, the presently
available data do not indicate the presence or a permanent divide between
the site and Well 12A. It should be noted that the assumptions built into
a model greatly influence the output, and the ultimate test of model
validity is the extent to which the predicted results agree with the data.
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A second general line of argument raised by the PRPs 1s to question
whether the s4te is the only, or primary, source of
1,1,2,2-tetrachloroethane contamination. They cite differences in the
ratios of 1,1,2,2 tetrachloroethane to trichloroethylene between the site
and Well 12A, the time from start-up of pumping at Well 12A until peak
concentrations are reached, and alternative interpretations of
concentration contours. EPA's consultant has reviewed these and other
comments, but points out that the presence of the highest concentrations
of 1,1,2,2-tetracholorethane in the immediate vicinity of the site tends
to link the site^ajd Well 12A. Further, explanations responding to the
PRP comments are available which continue to support the interpretations
of the EPA. The reader is referred to the letters from CH2M Hill, dated
January 4, 1985. and February 13, 1985, for further discussion of the
merits of the RI/FS and the PRP comments.
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