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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FIGURE 5
WATER TABLE CONTOURS
FOR 4/4/84 DATA
                                                                      South T*conu Channel ROD

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                                                                                          • • Wiltf S«np1« • U|/l
                                                                                          • • 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.

-------
                                     17
                                                                   NO
               .
       ,-           r'  -••-   I  ; l     •
       /       -        '-    I  c l -   «  » * .     I   « C • :   «
 t    /       ^^^  n^.^: Lc r      '  •' •    •';«/.:
           '-• . * 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

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                                                            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.

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                                                                    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

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                                         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 
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                                                           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.

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                                   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

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                                                            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.

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                                                                      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

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                                                         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.

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                                     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.

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                                    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

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                                                         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.

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                                                           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

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                                                           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.

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                                      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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                                                           34

                                     17

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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                                                          35

                                     18

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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                                                          36
                                     19
                      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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                                                         37
                                     20


                                  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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                                       38


                           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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                                                           40
                                     -3-


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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                                     -5-
     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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                                                        43

                                     -6-


     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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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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                                                        45
     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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