REPC&T DOCUMENTATION '• REPORT NO. ; 2.
2/£K PAGE EPA/ROD/R10-88/016 !
4. Tittt. »«d Subtitle
SUPERFUND RECORD OF DECISION
Commencement Bay/Tacoma, WA
^Yirst Remedial Action - Final
J Authors)
9. Performing Organization Name and Address
12. Sponsoring Organization Nam* and Address
U.S. Environmental Protection Agency
401 M 'street," S.W.
Washington, D.C. 20460
3. Recipient's Accession No.
5. Report Oat*
03/31/88
6.
8. Performing Organization Rept. No
10. Project/Tasl ,
The Commencement Bay/Tacoma siteTis a 190-acre industrial/municipal landfill located
in Pierce County,. 'TaconaV Washington. The landfill is'operated by the City of Tacoma
Refuse Utility and is surrounded primarily by residential development and open'land,
with some commercial and industrial development. Several utilities (i.e., sewer, water,
and storm) pass through the site. An aquifer beneath the site provides drinking water
to the Town of Fircrest and the city of Tacoma, both of which have wells near the
landfill. The aquifer is also used by private individuals for their domestic water
upply. Ground water' flows predominatly to the southwest toward Leach Creek, which lies
approximately 0.25 mile west of the landfill. consequently, wetlands downstream of the
landfill could potentially be exposed to contaminants in the surface water and ground
water. The Tacoma landfill began operations in 1960, receiving only nonhazardous wastes
including assorted municipal and industrial wastes, construction and demolition wastes,
and bulk waste. To date, about 4 million tons of refuse have been deposited at the
landfill to depths of 20 to 80 feet. Although the landfill does not accept hazardous
wastes for disposal, it did receive wastes in the 1960s and 1970s that have since been
designated as hazardous substances. In 1983, investigations by EPA revealed the
presence of hazardous compounds in the ground water and soil near the landfill.
(See Attached Sheet)
i°6'nc'1ptor*
Commencement Bay/Tacoma, WA
First Remedial Action - Final
Contaminated Media: sw, soil
Key contaminants: VOCs (benzene,
ti. Id*ntlfi*rs/Op*n-End*d Terms
toluene, xylenes), metals (chromium)
c. COSATI Field/Group
Availability Statement
19. Security Class (This Report)
None
20. Security Class (This Page)
None
21. No. of Pages
121
22. Price
(See ANSI-Z39.18)
See Instructions on Reverse
OPTIONAL FORM 272 (4-77)
(Formerly NTIS-35)
Department of Commerce
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(PA/ROD/R10-88/016
ommencement Bay/Tacoma, WA
irst Remedial Action - Final
16. ABSTRACT (continued)
Subsequent investigations indicated that the ground water is contaminated with VOCs. In
response, the City of Tacoma connected affected residences to the public water system.
In 1986, accumulation of landfill gas in a utility vault adjacent to the landfill
resulted in a minor explosion. A field survey was initiated to evaluate the extent of
offsite gas migration, and based on this survey a gas extraction system was constructed
to extract, collect, and combust the gas. Gas samples collected at the landfill
revealed high levels of VOCs. The primary contaminants affecting the ground water and
surface water are VOCs including benzene, toluene, and xylenes.
The selected remedial action for this site includes: construction of a cap on the
landfill with runoff directed to appropriate storm or sanitary sewers, and installation
of a gas extraction system and gas probes to monitor methane gas production;
installation of a ground water pump and treatment system with discharge of treated water
to a local creek or the POTW and alternate water supply if needed; and ground water and
surface water monitoring. The estimated present worth cost for this remedial action is
between $21,015,000 and $23,418,000. The estimated O&M costs were not provided.
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION 10
1200 SIXTH AVENUE
SEATTLE, WASHINGTON
RECORD OF DECISION,
DECISION SUMMARY, AND
RESPONSIVENESS SUMMARY
FOR
FINAL REMEDIAL ACTION
COMMENCEMENT BAY - SOUTH TACOMA CHANNEL
TACOMA LANDFILL SITE
TACOMA, WASHINGTON
MARCH 1988
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RECORD OF DECISION
REMEDIAL ALTERNATIVE SELECTION
FINAL REMEDIAL ACTION
COMMENCEMENT BAY - SOUTH TACOMA CHANNEL
TACOMA LANDFILL
TACOMA, WASHINGTON
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RECORD OF DECISION
REMEDIAL ALTERNATIVE SELECTION
Site
Commencement Bay - South Tacoma Channel, Tacoma Landfill site - Tacoma,
Pierce County, Washington.
i
Purpose
This decision document presents the selected final remedial action for
the site, developed In accordance with the Comprehensive Environmental
Response, Compensation, and Liability Act of 1980 (CERCLA). as amended by the
Superfund Amendments and Reauthorlzatlon Act of 1986 (SARA), and consistent
with (where not precluded by SARA) the National Contingency Plan (NCP, 40 CFR
Part 300). The State of Washington, In close consultation with EPA, has
developed and concurred with the selected remedy. A copy of the state
concurrence letter Is attached as Appendix 0.
Basis for Decision
The decision Is based upon the administrative record for the site, as
obtained from the files of the Washington State Department of Ecology and the
U.S. Environmental Protection Agency (EPA). This record Includes, but Is not
limited to. the following documents:
o Remedial Investigation Report for the Tacoma Landfill, Tacoma,
Washington (December 1987)
• •*
o Feasibility Study of the Tacoma Landfill Site, Final Report
(December 1987)
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o Decision Summary of Remedial Alternative Selection
o Responsiveness Summary (attached as Appendix 8)
o Staff summaries and documents—An Index (Appendix C) Identifies
other Items which are Included In this administrative record.
Description
This record of decision (ROD) addresses source control of on-slte
contaminants through capping of the landfill and extraction of methane gas.
\^
Management of migration for off-site contaminants will be through a
groundwater extraction and treatment system.
The remedial action Is designed to:
o reduce the production of leachate by placing constraints on further
site operations and by capping the landfill.
o eliminate off-site gas migration through the gas extraction system.
o prevent further migration of the contaminated plume via the
groundwater extraction-treatment system.
o further protect public health and the environment via monitoring of
groundwater, surface water, gas probes, and air emissions.
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o provide an alternate water supply (Tacoma municipal water) to any
residents deprived of their domestic supply due to demonstrated
contamination from the landfill or due to the action of the
extraction-treatment system.
Treatment will be sufficient to reduce contaminant levels in the
groundwater to or below cleanup standards. Performance levels for the
Identified contaminants of concern are presented in Table 8. The methodology
to be used to develop performance levels for the other contaminants in the
groundwater Is discussed in the Selected Remedial Alternative section of the
ROD. Treatment should be permanent, and should effectively reduce the
toxldty and mobility of the contaminants. Performance levels are not to be
exceeded during the operational life of the remedial action. Treated water
discharge shall at all times be consistent with federal laws and Washington
State laws. Any treatment system which will produce air emissions will be
designed to meet appropriate federal and state Air Toxics Guidelines and to
use Best Available Control Technology (BACT) on the effluent air stream.
Containment of the plume will be confirmed by Installation and periodic
sampling of monitoring wells as well as continued, scheduled monitoring of
private and public wells. Extraction will continue until water quality at the
compliance boundary (defined by WAC 173-304 as the edge of the filled area)
consistently meets or exceeds drinking water standards, or previously
established and approved health-based criteria. In addition to meeting
health-based criteria, potential Impacts to public and private water supplies,
and to Leach Creek must be considered In the decision to shut off the system.
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Those residents who are deprived of domestic drinking water, either
because their wells water quality shows demonstrated contamination from the
landfill or because the quantity available has been reduced by the action of
the extraction-treatment system, will be connected to city water supplies.
Source control measures are expected to reduce contaminant concentrations
In the groundwater system. Source control measures consist of constructing a
cap on the landfill and appropriate regradlng to minimize Infiltration and
maximize run-off, ultimately reducing leachate volume and toxlclty. Unllned
areas of the landfill will be capped as soon as possible. WAC 173-304 defines
the minimum requirements for a cap on a municipal landfill. A more stringent
\^
cap will be required unless further analysis of the cap, to be provided during
remedial design, shows that a significant reduction In leachate volume or
toxlclty would not be achieved.
Increased run-off due to the construction of the cap will be routed off
the landfill to reduce Infiltration. The run-off collected from the landfill
will be directed to the appropriate storm or sanitary sewers, consistent with
local storm drainage ordinances or pre-treatment regulations. The storm
drainage plan, prepared as part of the remedial design, will determine and
minimize any Impacts on downstream Increases In peak. flow.
The city of Tacoma (Tacoma) will Implement a closure plan for the
landfill consistent with Washington State Minimum Functional Standards for
Landfill Closure (WAC 173-304). and as appropriate, Washington State Dangerous
Waste Regulations (WAC 143-303).
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Institutional controls will be Implemented, consistent with the final
design, to assure that the remedial action will continue to protect health and
the environment. Tacoma, In cooperation with the town of Flrcrest and Pierce
County, will pursue the establishment of an ordinance, or other suitable
methodology, to restrict drilling of water supply wells In an area from Tyler
Street to Leach Creek, and from Center Street to approximately South 56th
Street.
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Declaration
Consistent with CERCLA, as amended by SARA, and the NCP, It 1s determined
that the selected remedy as described above Is protective of human health and
the environment, attains Federal and State requirements which are applicable
or relevant and appropriate, and Is cost-effective. This remedy satisfies the
preference expressed In SARA for treatment that reduces toxlclty, mobility, or
volume. Finally, It Is determined that this remedy utilizes permanent
solutions and alternative treatment technologies to the maximum extent
practicable.
Date Regional Admlniswaror
Environmental Protection Agency
EPA - Region 10
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DECISION SUMMARY
REMEDIAL ALTERNATIVE SELECTION
FINAL REMEDIAL ACTION
TACOMA LANDFILL
TACOMA, WASHINGTON
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TABLE OF CONTENTS
Page
I SITE DESCRIPTION AND LOCATION i
II SITE HISTORY . 3
A. Landfill History and Operations 3
B. Regulatory History - Previous Investigations 4
C. The Remedial Investigation/Feasibility Study 5
III SITE ENVIRONMENT s
IV NATURE AND EXTENT OF PROBLEM 9
A. Extent of Gas Migration -. 9
B. Contaminants Detected 13
C. Extent of Groundwater Contamination 14
D. Surface Water 16
E. Future Impacts 17
F. The Endangerment Assessment 19
V ALTERNATIVES EVALUATION - FEASIBILITY STUDY 27
VI SELECTED REMEDIAL ALTERNATIVE as
A. Description of the Selected Remedy 35
B. Statutory Determinations 43
VII ENFORCEMENT 49
VIII COMMUNITY RELATIONS so
APPENDICES
A. APPLICABLE AND APPROPRIATE REQUIREMENTS
B. RESPONSIVENESS SUMMARY
C, INDEX TO ADMINISTRATIVE RECORD
D. STATE CONCURRENCE LETTER
11
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LIST OF TABLES
Table 1
Table 2
Table 3
Table 4
Table 5
TableS
Table?
TableS
Figure 1
Figure 2
Figured
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9
Figure 10
Figure 11
Summary of Organic Compounds Detected in Landfill Gas
Threshold Limit Values for Landfill Gas Components
Organic Waste Components Detected at the Landfill
Metals Detected at the Landfill
Travel Times to Reach Maximum and Threshold
Concentrations, Close-in and Distant Wells
Summary of Detailed Evaluation of
Remedial Alternatives
Section 121(bXlXA-G) Evaluation Factors
Performance Standards for Treatment System/Discharge
to Surface Water
LIST OF FIGURES
Site Location
Site Vicinity
T-andfili Zoning
Leach Creek Drainage Basin
t-ar*^ii Site Cross Section and Lithology
Location of Private Wells/Extent of Contamination
Landfill Drainage Patterns
Landfill Gas Extraction System
Contaminant Distribution in Groundwater
Contaminant Distribution in Groundwater (continued)
Current and Predicted Contamination
following
Page
11
12
14
14
24
32
32
37
1
1
1
6
7
8
8
9
15
15
18
111
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I. SITE DESCRIPTION AND LOCATION
The Tacoma Landfill, operated by the City of Tacoma Refuse Utility, Is
located In Sections 12 and 13 of Township 20 North, Range 2 East, Pierce
County. Washington. The landfill covers 190 acres and Is bounded
approximately by South 31st Street on the north. Tyler Street on the east,
South 48th Street on the south, and Orchard Street on the west. Figures 1, 2
•
and 3 Illustrate the location of the landfill, the vicinity surrounding the
landfill, and the site itself. The landfill serves a population of
approximately 212,000. To date, approximately 4.0 million tons of refuse have
been deposited at the landfill since It operted In 1960. Currently about 600
tons per day of refuse are placed In the landfill.
The landfill does not accept hazardous wastes for disposal. However, the
landfill received wastes In the 1960s and 1970s that have since been
designated as hazardous substances under State and Federal law.
Figure 2 shows the general topography of the landfill and surrounding
area. Orumllns (low, long ridges) abound In the general area and display a
north-south axial configuration. Solid waste has been disposed of at the site
between five drumllns. The landfill's western boundary Is approximately one
quarter mile from Leach Creek, but the landfill does not lie In the flood
plain of that creek. The landfill Is surrounded primarily by residential
development and open land, with some commercial and industrial development.
Land use for the area surrounding the landfill 1s shown on Figure 3. No use
of natural resources other than groundwater 1s noted on land use Inventories.
-#
Several utilities (sewer, water, and storm) pass through the site.
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STATE OF WASHINGTON
0124 3
SCALE : I* = 4 MILES
FIGURE I
SITE LOCATION M*
TACOMA LANDFILL ^
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2000' 1000' 0
2000'
4000
FIGURE 2
SITE VICINITY
PRODUCTION WELL LOCATIONS
• TACOMA LANDFILL RI/FS
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TACOMA
LANDFILL
LEGEND
COMMERCIAL
INDUSTRIAL
RESIOENTAL
JOOO 2000
SCALE l-* 2000'
4000
FIGURE 3
LANDFILL ZONING.*'
TACOMA LANDFILL
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Apartments, undeveloped land, and commercial properties including a
bowling alley, offices, building supply and paint stores, and gas stations are
located north of the landfill. Immediately east of the landfill are apartment
complexes, single family residences, and undeveloped land. The area further
east between Tyler Street and South Taccma Hay Is occupied by the Burlington
Northern Railroad, Industrial/commercial development, and an open area known
as the South Tacoma Swamp. Between the west edge of the landfill and Orchard
Street there are several apartment buildings and commercial establishments.
West of Orchard Street and south of the landfill there is residential
development and undeveloped land.
\
The landfill lies In the central portion of the Tacoma/Flrcrest upland
ground water system. A significant area for the central upland In the
vicinity of the landfill Is Leach Creek.
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II. SITE HISTORY
A. Landfill History and Operations
The Tacoma Landfill began operations in 1960, and now serves a population
of approximately 212.000. The wastes received and disposed at the landfill
Include garbage, rubbish, industrial wastes, construction and demolition
wastes, street refuse, litter, and bulky waste. To date, approximately 4.0
million tons of refuse have been deposited at the landfill. Filled areas vary
from 20 to 80 feet deep. Currently some 600 tons per day of refuse are placed
In the landfill.
Most of the site has already been filled. The next section of the site
to be filled Is called the Central Area Pit. This section of the landfill
covers approximately 18 acres and was developed during the summer and fall of
1987. A flexible membrane liner and leachate collection system were Installed
In the Central Area Pit. The liner and leachate collection system were
designed primarily to maximize volume for waste disposal. To date, there has
been no documentation received on the integrity of the liner.
Day to day operations of the landfill are regulated by the Tacoma-Plerce
County Health Department (TPCHD) with oversight by the Washington Department
of Ecology (Ecology); the operating permit Is Issued annually by TPCHD.
At the current rate, the 190-acre site has a remaining life expectancy of
approximately four to five years if all the solid waste material is disposed
without a significant reduction In volume. Tacoma has indicated it Intends to
Implement programs to extend the life expectancy of the landfill.
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There are many large and small Industries in the Tacoma/Plerce County
area which have disposed of wastes at the landfill. Memoranda reviewed during
the preparation of the Description of Current Situation report and the RI
indicate that some hazardous wastes were disposed of at the landfill.
Investigations concerning the volumes, the chemical composition of the wastes,
and the disposal locations are ongoing.
B. Regulatory History - Previous Investigations
In 1983 EPA conducted an investigation and detected hazardous compounds
X
In samples of ground water and soils near the landfill. This led EPA to
Include the landfill on the National Priorities List of hazardous waste sites
as part of the South Tacoma Channel site. Through a cooperative agreement
with EPA, Ecology began an Investigation Into- contamination at the site In
1984. On June 27. 1986, Tacoma assumed responsibility for conducting the
remedial Investigation and feasibility study under a Response Order on Consent
Issued by Ecology.
Since 1983 testing has been conducted at and around the Tacoma Landfill
by EPA, Ecology. TPCHD, Tacoma, and others. The testing revealed that three
private wells contained contaminants. The priority pollutant volatile organic
compounds which were detected In the ground water samples were primarily
chlorinated organics. Twenty-four volatile organic compounds were found In
groundwater contaminated by the landfill.
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Because of the concern about the public health effects of the
contaminants, particularly vinyl chloride, the TPCHD recommended that Tacoma
connect these affected residences to the Taccma public water system. As a
precautionary measure. Tacoma also connected two additional residences whose
wells were near the area. Monitoring continues quarterly to ensure the clean
water supply for potentially affected residents while appropriate cleanup
actions are approved and carried out.
C. The Remedial Investigation/Feasibility Study (RI/FS)
The remedial investigation (RI), conducted by Tacoma1s consultant. Slack
and Veatch. was performed in two phases. Phase 1 activities (July 1986
through January 1987) consisted primarily of field Investigations to
characterize both the hydrogeology of the site and tfre contaminants present In
the various media at and surrounding the site. Phase 2, conducted from
January through November 1987. was designed to fill in data gaps Identified at
the conclusion of Phase 1 and to provide the data necessary for the
endangerment assessment and the feasibility study (FS).
Upon completion of the RI and and evaluation of the alternatives, the
City, through their consultants (Black and Veatch). submitted a draft RI and
FS report In September and October 1987 for agency review and approval. The
final RI/FS reports were published December 1987. Public comment on the
studies was completed In March 1988.
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III. SITE ENVMBIT
The Tacoma Landfill site is located In the northern portion of the
Chambers/Clover Creek d-iinage basin (see Figure 4). This area is part of the
Puget Sound lowland. The study area is bounded by: the Tacoma channel to the
east; Center Street to the north; 56th Street to the south; and Leach Creek to
the west.
A moderate climate prevails. Winter temperatures are seldom below
freezing and summer temperatures are rarely above 80*F. Approximately
thirty-seven Inches of rain fall in a normaKyear. Studies conducted In the
Puget Sound region have Indicated that approximately 301 of rainfall becomes
groundwater.
The geology of the site consists of a series of glacial materials, mostly
sand and gravel laid down over older alluvial silts and sands. The
stratlgraphlc units (layers) described In the Remedial Investigation (Black
and Veatch, 1987) from youngest to oldest (top down) are:
A. Vashon Till (dense gray, gravelly, sllty, sand) (Qvt)
B. Vashon Advance Outwash (sands/gravels) (Qva)
C. Colvos Sand (dense sand/some gravel) (Qc)
0. Older Gravel (dense sandy gravel) (Qog)
E. Older Till (dense sllty, gravelly sand) (Qot)
F. Older Outwash (dense sllty. gravelly sand) (Qoa)
G. Older Sand (dense fine/medium sand) (Qos)
H. Older Lacustrine (lake bottom silts) (Qol/Qk)
I. Und1fferent1ated Quaternary Sediments (Qu)
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SPRING
FLOW-G
LEACH CREEK
DRAINAGE
HASINA
FLETT CREEK
DRAINAGE 3ASIN
UMVERSIT
\ r
y-TACOMA
/ UANDFILL
FIGURE ADAPTED FROM CLOVER/
CHAMBERS CREEK <3£OHYOROUOG1C
STUDY
SCALE IN MILES
FIGURE 4
LEACH CREEK DRAINAGE BASIN
TACOMA LANDFILL Ri/FS
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The affected aquifer is located between the lower zones of the Colvos
Sand and the Older Lacustrine. The Older Lacustrine unit serves as the
regional aqultard In the landfill area. A cross section through the area
(Figure 5) shows the ridges, valleys, and the lithology (layers).
Water, Infiltrating through the landfill, picks up various contaminants.
Where the Vashon Till Is not present beneath the waste, contaminants move with
the water through the unsaturated zone and into the aquifer. It is also
possible for low solubility, pure phase fluids, called dense, non-aqueous
phase liquids (DNAPLs). such as chlorinated hydrocarbons to enter the
aquifer. Evidence of this has not been shown, nor has It been disproven. The
water table lies within the Colvos Sand unit, about 70 feet below the bottom
of the landfill.
The predominant flow direction of the water table aquifer Is
southwesterly toward Leach Creek. However, during periods of heavy water use
by Tacoma city wells (summer and early fall), the groundwater flow direction
Is reversed. Also, depending on local conditions, groundwater and contaminant
movement may be downward or upward.
The Older Alluvium reportedly forms the confining layer. Leach Creek Is
the closest discharge point of the aquifer. Additional information from
future activities will clarify the ground water flow conditions near the creek
and elsewhere around the site.
The aquifer Is part of the Chambers/Clover Creek Ground Water Management
Area. The TPCHD Is petitioning EPA for a Sole Source Aquifer designation for
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5
400 r
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300
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SOUTH
TACOMA
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prepared by llari Ciowser. Inc.
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calculated Irom av«iag« ««iilc*l gradients over seven (7) tels ol
waiar level miacuiemenis (Table 4-21 and therefore lepresenl
anlicipaled average conoiilons.
2 Flowitnes are diawn qualliallvelv assuming a moderate degree ol intiolropy
Mel Number
WelLocaUon
Water Table
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this aquifer. The Town of Fir-crest and the City of Taccma both operate wells
near the landfill (see Figure 2). In addition, the aquifer Is also used by
private Individuals for domestic water supply (see Figure 6).
Wetlands downstream of the landfill on Chambers Creek could potentially
be exposed to contaminants In the surface water and ground water. None of the
five endangered species identified in the State of Washington Is common to the
area surrounding the landfill.
The topographical lowpoint in the landfill is currently at the north end
of the Central Area Pit. Some runoff from surrounding areas drains and
discharges to the sanitary sewer. Drainage from the north and along Mullen
Street Is directed towards a pond situated between the bowling alley parking
lot and northern landfill property on Mullen Street. Drainage from the west
side of the site Is directed toward a catch basin and discharges to the Leach
Creek retention basin. The south end of the site drains to the south and is
not collected. Drainage patterns are shown in Figure 7.
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-------
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IV. MATURE AM) EJtTHT OF
A. Extent of Gas Migration
In May 1986. accumulation of landfill gas In a utljlty vault at the Town
Concrete Pipe Company (located Immediately adjacent to and west of the
landfill) resulted In a small explosion. Tacoma had already hired a
consultant (Mandevllle Associates) to address problems of gas production and
migration at the landfill and was able to Immediately Initiate a field survey
to evaluate the extent of gas migration off-site. Based on this survey, the
consultant designed and constructed a gas extraction system to extract,
collect and combust the gas. The field survey showed the biggest problem to
be southwest of the site and this Initial effort concentrated on controlling
gas from migrating Into businesses In this area.
The current landfill gas system consists of 128 extraction wells,
collection piping. 77 gas probe locations, and the motor blower/flare station
where contaminants are Incinerated. The system layout Is shown on Figure 8.
Tacoma has conducted a two-stage gas monitoring program to monitor the
effectiveness of the extraction system. Figure 8 shows the locations of 66
probes Installed around the landfill. Each of these probes consists of two
to five probes able to monitor gas at depths from 6 to 70 feet. These probes
are checked twice a week and seem to Indicate that the shallower gas Is being
controlled by the extraction system.
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The gas found deeper than about 35-40 feet is not being controlled as
well. As a result of this information. Tacoma is installing approximately 74
new, deep extraction wells around the landfill. This work began on
January 27, 1988.
The City has also been conducting an off-site monitoring program
beginning in May. 1986. From May 1986 until August 1987, this program focused
on businesses and apartments to the south and west of the site, where both
ambient and point source measurements were taken. Beginning in August 1987,
the current off-site monitoring system began. This consists of monitoring
utility vaults In residential areas (shown on Figure 8). and routine ambient
\
and point source monitoring in some businesses and vacant apartments. The
data from this effort shows that methane Is still escaping the landfill and
finding Its way to the surface In off-site locations. The utility vault data
shows several areas, around the landfill to be of particular concern.
The Minimum Function Standards require that the concentrations In
off-site structures be below 100 parts per million (ppm) by volume of
hydrocarbon In ambient air. From November 1986 through October 1987, the
readings of ambient air In off-site structures were below the limit; however,
some point sources monitored such as foundation cracks and closed vaults on
occasion have shown readings above 100 ppm. Readings above the limit were
found In the ambient air In one building west of the landfill near 40th
Street (Classic Auto) In November 1987. The City Installed four additional
gas extraction wells In this area In December 1987. No readings were detected
In the building after the first well was connected to the system on
December 15, 1987.
10
-------
Ecology has requested that additional gas probes be placed in the
neighborhoods of concern. The existing probes are well within the influence
of the gas extraction wells and do not represent ambient conditions further
off-site. Methane concentrations in utility vaults can also be misleading.
Gas concentrations fluctuate a great deal with changing atmospheric
conditions. Therefore, it is possible that landfill gas could be found in a
house without observing it in the vault. Additional gas probes are needed to
better determine the performance of the gas extraction system.
A total of 42 landfill gas samples were collected at 26 locations around
the landfill. The gas samples collected from gas wells and probes were
analyzed for priority pollutant volatile organic compounds (VOC). The
analytical results are summarized in Table 1. The methane concentration was
analyzed for five of the Phase 1 samples and was field measured for seven of
the Phase 2 samples. These results are presented below:
Sample No.
Methane (ppm)
Sample No.
Methane (ppm)
Phase 1
GS-001
GS-002
GS-002DUP
GS-003
GS-004
540.000
430,000
430.000
560,000
240.000
Phase 2
GS-213
GS-214
GS-215
GS-218
GS-219
GS-220
GS-221
370.000
480.000
610,000
560,000
200.000
200,000
200,000
11
-------
ORGANIC C
OF ?1UO«i7T MLiJTAKT VOtATILI
3C7XCTZD IS LjUTCm:. CAS SAK?'_£S
Caac*ncracLanj La
04/23/14
04/23/M
04/23/14
04/U/M
04/23/M
04/23/M
04/23/M
04/23/M
04/23/M
04/23/M
04/23/M
04/23/M
00/24/M
01/24/M
11/13/M
12/09/14
12/09/14
02/12/17
02/10/17
02/10/«7
02/10/17
02/12/17
02/12/17
02/10/17
02/10/«7
02/10/17
02/10/17
2400
700
1200
24OO
2900
1100
laoo
1000
1100
1100
2000
4«00
13.30
2200
41OOJ
2100
1400
2400J
3400
• 40J
1200
2400
4100
2400
2600
2400
1200J
Qilora-
'.400
:30O
1230
940
930
1400
3COO
1130
1600
3000
1200
100
710
230
1000
130U
1000
1000U
300U
1COO
laoou
10000
IOOOO
10000
IOOOO
IOOOO
1000U
Qiian-
• t--.«n«
1.00
IOOOO
300
2300
2300
13000
4100
13000
1300O
T»
n
1400
33.30
430
2300J
9100
1000
2000U
12000
2000
IMOJ
1200
2200
1300J
1400J
20000
2000O
i.l-Ol-
chlaro-
T»
3000
1230
1230
1230
3000
3000
300O
300O
900
3000
1700
13. JO
1400
3 IOOJ
2000
2200
100 OU
14001
IOOOO
400J
13001
1300
IOOJ
1300
IOOOO
IOOOO
1.2-01
ehlar*-
3000
3000
1230
1230
1230
3000
3000
3000
3000
T*
3000
12000
33.30
230
1000
1600
1300
1000U
3000
IOOOO
IOOOO
10000
1900
IOOOO
IOOOO
IOOOO
IOOOO
1,1-01-
chlor*-
3000 '
j oca
1230
1230
1230
3000
17000
3000
3000
TB
1000
T*
13.30
43
1000
100
100
IOOOO
3000
10000
IOOOO
10000
320J
IOOOO
34OJ
IOOOO
IOOOO
Tcaiu-
1.2-01
chlor*-
2300
T*
300
130
1230
700
12000
300O
3000
23000
16000
120000
13.30
1200
13000J
20000
19000
•600J
7700
600J
2400
3000
3MOO
9400
34OOO
4400
_ IOOOO
CBCAMIC
TAIU 1 (cone)
or PUOUTT nujrum VQLATIU
CCKFOOfDS OC7ZC7IB 19 LjUTCf Oi. CAS SAMFU3
Cane ant rat Jam La u«/mj
1.1.1-
Loot lona
CW-O1
9-21
9-43
9-12
9-32
9-1 3D
9-133
9-230
9-231
9-069
9-04*.
rs-oi
9-13
9-1*
9-TL-01A
FLARI
ruutz
CU-22
01-12
OJ-21 CAST
OI-21 SW
CU-44
CU-1*
CU-4.
cw-*d
01-43
OJ-*3
-------
The landfill gas contains significant concentrations of VCCs and has been
proposed as a possible migration pathway for these compounds to the
groundwater, particularly when groundwater contamination is found upgradient.
The American Congress of Governmental Industrial Hyglenists has Issued
threshold limit values (TLVs) on airborne concentrations of various
substances. These limits are intended as guidelines in the control of
potential health hazards. The time-weighted average (TWA) TLV concentration
for a normal 8-hour workday and a 40-hour workweek is the concentration which
nearly all workers might be exposed to without adverse effect. The compounds
detected In landfill gas samples that exceeded 15 percent of the TWA values
are given In Table 2. Two of the TWA's were exceeded (toluene and vinyl
chloride). The detected concentrations listed In Tables 1 and 2 are from
samples collected Inside the respective gas well or probe and are not
representative of ambient air concentrations.
EPA's ISCST (Industrial Source Complex Short-Term) dispersion model was
used to. predict the potential landfill air quality Impacts. Toluene was
generally detected at higher concentrations than other VOCs In the landfill
gas samples and had the highest mass flow rate both in and out of the flares
during the flare test; therefore, it was selected as the pollutant to be
assessed by the air quality analysis.
The worst case analysis predicted the highest toluene concentration
(using a one hour averaging time) to be slightly greater than 2 ppb. The
Draft New Source Guidelines for Toxic Air Contaminants (Sept. 1986) for the
State of Washington indicate a 14 ppb toluene to be the acceptable ambient
12
-------
TAflLE 2
T31IS3CCJ L2CT VAL3C3 ro
CAS CCHPOUXOS
(CAS
(71-4J-2)
oro«
(73-1S-4)
«-1.2-0le
(3*0-3»-0)
(75-Of-2)
Oxlorlda (73-01-*)
2-Baunoo* (391-7t-4)
Tot«i XjLmamt (1330-20-7)
1.2-OteAiaroachjLfM (107-04-2)
S*BDl. So.
3S-012. SS-217
Oi-007
5S-012
SS-011
33-007
SS-010
SS-217
33-011
1S-011
CS-012
"• ir—~*
3«e*et»d
u«/«I
4. tOO
17.300
120. 000
77.000 (2)
73.000
lao.ooo
124.000
1.200
170.000
12.300
7P"
19
3
200
:oo
130
100
3
3
100
10
u«/»3
30.300
:0.35C
790.300
433. 30C
330.300
373.300
10.000
20 . 300
433.300
40.000
lua of 160.000
Awcac*. )Uf«c«nc« 34.
for
d In
Ln
CS-217i
-------
level; therefore, it would appear that as long as the current gas collection
system remains functional, ambient air concentrations of VCCs should remain
well below ambient air standards.
B. Contaminants Detected
Groundwater, surface water, leachate. sanitary sewer, subsurface soil,
sediment and landfill gas samples were collected during the RI sampling
program. The prevalent contaminants detected during the sampling program were
volatile organic compounds followed by semi volatile organic compounds and
metals.
Twenty-four volatile organic chemicals were found in the groundwater. Of
the twenty-four chemicals, the following seven Indicator chemicals were
Identified In the Endangerment Assessment in the RI as being of most concern
because of their toxlclty, frequency of occurrence, and primary targets (human
population):
o vinyl chloride
o benzene
o 1,2-dlchloroethane
o methylene chloride
o 1,1-dlchloroethane
o chloroethane
o toluene
13
-------
In addition, review of the Endangerment Assessment by EPA and Ecology resulted
In the inclusion of three additional indicator chemicals listed below:
o xylenes
o 1,1,1-trlchloroethane
o ethyl benzene.
The rationale for Inclusion of these chemicals Is discussed further In the
Endangerment Assessment section of this document.
Twenty three private drinking water wells were sampled during the
sampling program. For the three wells where contamination exceeded drinking
water standards, the City of Tacoma connected the residents to City water.
As the plume spreads. It is predicted more private wells would become
contaminated at levels above public health standards unless actions are taken
to restrict the movement of the plume.
A list of hazardous organic compounds (priority pollutant and hazardous
substance list compounds) detected in groundwater samples analyzed during the
RI Is given in Table 3. Table 4 provides the list of priority pollutant
metals detected at the landfill.
C. Extent of Ground Water Contamination
The contaminant pathway of primary concern near the landfill is the
ground water. The town of Fircrest supplies water to its residents from six
ells located west of the landfill. Three of these wells are only
14
-------
Uj>t« CuBH'OI'ClU
Volilllt Ot««iilc CoiBPoundi
T«l t achloKMthin*
TIUII- 1 . 2-Dlcltloro*th*n«
Tt lcliloro«ih«ii«
I , l-Dlcliloro«lh*n«
Vinyl Clilorld*
1,1. 1 -rt lchloro«lhui«
I. l-Dlchlofo«llt*M
1.2 DIcMoiodliaiM
Clilot ob«ni«it«
Tuliicna
XyUiM (Tool)
2 • Buiftnoii*
2 ll*«aikoii«
1.2. -Dlcliloropcop*n«
T(*III- I , l-Dichloioprop«n«
Slycin*
(Uibon D I lull Id*
Qilorotor*
K*thyl«n* Otlocld*
Ac«ton*
4-H*ilirl -2-p*n(»non«
PMA.
Ph«nol
rtlulcl* Etltrt
1 ,«-OUhlo(ob«n<«n«
H-Hltro-Sodl-
ph*nf IMMH*
ft*iujfl Alcohol
••mole Acid
TABLE 3
ORGANIC HASTE COMPONENTS DETECTED AT THE TACOMA LANDFILL
Subiurfac*
Soli
Ground-
Surfcc*
_£**'_
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
x
i
i
X
X
x
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
l«ophoio
• S*^>1«* not »rv»ljrt«d lor •••Ivolctll* compound*
b Oiilr tr*c« tmounlt of •••IvoUcll* oo^iound* w*r« d«t*ot«d in (round utttr
-------
TABLE 4
METALS DETECTED AT TACOMA LANDFILL
Subsurface Ground-
Soil water
Arsenic
Cadmium
Chromium
Copper
Mercury
Nickel
Lead
Zinc
Iron
Aluminum
Manganese
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
NA
X
Surface San. Sewer Sediment
Hater & leachate
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
NA
X
X
X
X
X
X
X
X
X
X
X
X
Gas
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA* not appl1 cable
-------
approximately 0.2 mile from the edge of the landfill. The City of Tacoma
operates nine wells to the east of the landfill to supplement summer peak
demands on their surface water supply (see Figure 2). In addition, twenty-six
known domestic wells are located near the landfill (see Figure 6).
Volatile organic compounds have been detected In .20 monitoring wells
Installed around the perimeter of the landfill during the RI and In six of the
private wells. The highest contaminant concentrations and greatest numbers of
compounds were generally found near the water table in the southern portion of
the landfill. Hater samples from monitoring wells TL-4, TL-3a. TL-lla, and
TL-12 Illustrate this occurrence. However, the highest concentration of vinyl
chloride detected to date on the site was drawn from a deeper portion of the
aquifer at monitoring well TL-lOb.
Contour maps Included In the RI report show the projected distribution of
seven of the contaminants of concern in the aquifer associated with the Tacoma
Landfill Site:
Maximum Concentration
a. Vinyl chloride 80 ug/1
b. Benzene 19ug/1
c. 1.2-dlchloroethane (DCE) 20 ug/1
d. Metnylene chloride 1300 ug/1
e. I.l-d1ch'-roethane (OCA) 42 ug/1
f. Chloroethane 55 ug/1
h. Toluene 60 ug/1
15
-------
CONTAMINANT DISTRIBUTION IN GROUNDWATER
VINYL CHLORIDE
1,2-OICHLOROETHANE
BENZENE
M€TMYLENE CHLO«ID€
CONCENTRATION CONTOURS IN UG/L
FIGURES
CONTAMINANT
IN GROUNDWATER
-------
CONTAMINANT DISTRIBUTION IN GROUNDWATER
• • i
HBCJUIT .
\n. 17
n»*«i
1
rw-a*
•»*'
.-U.-<
••p
..--•TV*
• ^^^ > «<
:; •"" ~'
L-/O
^
i7~1
U J_J
::^
m.
1X1 ,|
clii
,n
JL '3;
rw-i
^ /
«, 1 .rr. f /
1.1-OtCHLOROETHAWE
TOLUENC
f
*L
CHLOROfTHAHi
CONCENTRATION CONTOURS IN UG/L
TC£
FIGURE 10
CONTAMINANT DETRIB
IN GROUNDWATER (COt
-------
The contour maps are 0resented here as Figures 9 and 10 to show the general
pattern In which each contaminant has spread In the aquifer.
Priority pollutant semlvolatlle. base, neutral, and acid extractable
compounds were detected In trace amounts In a few of the ground water samples
collected at the site. Priority pollutant metals occasionally exceeded
maximum contaminant levels (MCLs) established pursuant to the federal Safe
Drinking Hater Act.
1,1,1-trlchloroethane was also found In measurable amounts In wells along
53rd Street West. Routine sampling of these wells has been on an annual basis
\^
and It Is possible that the landfill is not the only source of contamination.
This Is In the process of being evaluated.
D. Surface Water
Surface water testing throughout the study area, In general, did not show
a significant problem which could be attributed directly to the landfill. At
this time most of the surface water Is being controlled on-slte. There are
three notable exceptions to surface water control:
1. The retention pond to the north has been contaminated with toluene.
This chemical has also been detected In nearby monitoring well TL-17.
2. Nearby off-site storm sewers receive runoff which discharges to
surface water (Leach and Flett Creeks) without retention or
pre-treatment.
16
-------
3. Storm water from the landfill Is being conducted to the sanitary
sewer.
Leachate was surfacing on the working face that now comprises the east
side of the Central Area. The leachate Is now being conducted directly to the
sanitary sewer through a burled toe drain.
Sediment samples taken from nearby storm sewer outlets show elevated
values for metals. However the RI was Inconclusive citing other potential
sources in addition to the landfill. Surface water (storm water runoff) will
be addressed as part of the selected remedy.
E. Future Impacts
As part of the RI/FS, modeling was performed to project future
contaminant migration. Contamination has been verified In private wells
southwest of the landfill In the direction of Leach Creek.
Tentative flow paths were then plotted based on the mapping of ground
water levels over several months. Contaminant flow velocities and dispersion
ratios were then estimated and a simplified groundwater contaminant transport
model named Plume (Van der Heijde 1983) was run.
Receptor groups were assigned based on location of known contamination
and the assumed aquifer discharge. Wells closest to Orchard Street were
designated near. Wells downgradient from the near wells were called far.
Leach Creek was assumed to be the far boundary. The Fircrest wells were not
17
-------
included In the model because the flow path analysis did not show them in the
line of contamination. However, the flow path analysis was based on current
usage rates and pumping conditions of both Fircrest and the Tacoma wellfleld,
and did not take Into account any future changes to these conditions. The
Feasibility Study (FS) did not include flow path analysis under differing
usage rates and pumping conditions. Therefore, the model is appropriate for
prediction of future migration only as far as the assumptions remain valid.
The studies showed that the main plume of groundwater contamination may
reach 1200 feet southwest of the landfill. To the west and southeast It may
reach 200 feet and to the northeast about 800 feet. Figure 11 shows this
plume and how far it would spread if unchecked, and If the model assumptions
are correct. The modeling that helped predict the plume's spread assumed tha
pumping of the Fircrest and City of Tacoma <6a) wells will stay the same.
These wells are about 500 and 3500 feet from the site, respectively.
The model predicted that for the next 100 years the aquifer between the
landfill and Leach Creek would contain unacceptable levels of contaminants.
Table 5 lists the estimated maximum predicted off-site concentrations for the
seven Indicator chemicals In the RI, and the estimated times to reach maximum
concentrations at the dose In and distant wells.
18
-------
FIGURE 11
CURRENT AND PREDICTED CONTAMINATION
-------
F. Endangerment Assessment
An endangerment assessment was conducted at the Tacoma Landfill to
estimate the magnitude and probability of actual or potential harm to public
health or the environment caused by the threatened or actual release of
hazardous substances. The assessment presented in the RI addressed the
potential human health and environmental effects associated with the Tacoma
Landfill site In the absence of the any remedial action (I.e., the no action
alternative).
The no action alternative Is the baseline where no corrective actions
^
take place under Superfund. In the case of the Tacoma Landfill, however,
certain corrective actions will take place regardless of the actions taken
pursuant to the Superfund site cleanup. These corrective actions must be
conducted to meet the requirements of the Washington State Minimum Functional
Standards for landfills (MAC 173-304). These actions Include: developing an
operating and closure plan for the landfill, Installation of a cap,
Installation of a liner and leachate collection for ongoing disposal
activities, and Installation, operation and maintenance of a methane gas
extraction system.
The future operation and maintenance of the landfill gas extraction
system and planned refuse processing operations will restrict development of
the landfill. Therefore, the endangerment assessment for the no action
alternative assumes site access will continue to be restricted in the future.
Although several pathways of exposure can be postulated for the site (surface
-*
runoff. Inhalation of vapors and entrained dust), the primary pathway of
concern for this site is groundwater. Since access to the site will be
19
-------
restricted, the Importance of the air pathway will be reduced. The methane
gas collection system will also act to minimize the inhalation exposure
route. The target receptors are the private and public well owners within the
path of contaminant plume. Also of concern Is the possibility of heavy metals
and organics reaching Leach Creek, and ultimately Puget Sound, either by
surface or groundwater routes.
Health Evaluation
The public health evaluation Identifies potential threats to human health
In the absence of remedial action at the site. This evaluation process
Includes a hazard assessment, dose/response assessment, exposure assessment
and risk characterization.
Twenty-four volatile organic chemicals were detected In the groundwater.
Of these, seven were selected as contaminants of concern In the Endangerment
Assessment of the RI due to their frequency of occurrence, concentrations
found, and primary targets (human population):
o vinyl chloride
o benzene
o 1,2-dlchloroethane
o methylene chloride
o 1,1-dlchloroethane
o chloroethane
o toluene
20
-------
However, based .on EPA and Ecology's review of the Endangerment
Assessment, the following three additional organic chemicals have been added
to the list of contaminants of concern:
o xylenes
o 1,1,1-trlchloroethane
o ethyl benzene.
This new list of ten organic contaminants of concern were separated into
classes of potential carcinogens and noncarcinogens. Vinyl chloride, benzene,
1,2-dlchloroethane. and methylene chloride were selected as Indicator
potential carcinogens. Both vinyl chloride and benzene are classified as
human carcinogens by the EPA. Methylene chloride Is a B2, probable human
carcinogen, based on Inadequate data In humans and Increased Incidence In rats
and mice. It Is present both on and off-site at considerably less frequencies
of occurrence.. 1,2-d1chloroethane, despite being found even less frequently
than methylene chloride, is ranked as an EPA 82 carcinogen and Is Included for
that reason.
Chosen as noncarclnogen Indicator chemicals of concern were
1,1-dlchloroethane, chloroethane, toluene, xylenes, 1,1,1-trlchloroethane, and
ethyl benzene. The three chlorinated ethanes were encountered relatively
frequently In the samples, although 1,1-dlchloroethane occurs much less
frequently than the others. In general, the toxicity and bloconcentration
potential of the chlorinated ethanes Increases with Increased concentration.
All but the 1,1,1-lsomer are extremely soluble in water. Toxicity concerns
21
-------
from their Ingestlon.at significant levels in drinking water lie chiefly In
the areas of chronic liver damage and overall central nervous system
depression.
Toluene and xylenes were selected largely because of their high
frequencies of occurrence, chemical similarities, and potential ecological
risk. Toluene was the most commonly detected chemical in water samples
off-site, and was roughly equivalent to xylene as fourth most common on-site.
Ethyl benzene was Included as a chemical of concern because of Its relatively
frequent occurrence among the more minor chemicals, its leachabi11ty, and its
tendency to blodegrade relatively slowly in groundwater.
The Endangerment Assessment of the RI calculated the excess lifetime
cancer risks from Ingestlon of carcinogens in groundwater If no alternate
water supply Is provided, and an estimate of risk if there Is short term
exposure to the Indicator chemicals. Because so many chemicals, both
carcinogens and noncarcinogens, are present in the groundwater, the
possibilities of addltlvlty and synerglsm cannot be Ignored. However, the
Endangerment Assessment of the RI was largely modeled on the concept of the
predominant risk being due to the Ingestlon of water containing vinyl chloride
The calculation of carcinogenic risk, assuming no alternate water supply
1s provided, is based on a 70 kg adult consuming 2 liters of contaminated
groundwater for 70 years. The Increased risk of cancer If a 70 kg adult
consumes 2 liters of vinyl chloride contaminated groundwater (at a
concentration of 70 ug/L) for 70 years Is about 5 In one thousand.
22
-------
Carcinogenic risks have been calculated for the short term exposure
scenario, that a carcinogen migrates to a residential well the day after a
"carcinogen free" sample is collected. It Is estimated It will take
approximately four months from the start of exposure until contamination Is
detected In the next quarterly sample and before an alteVnate water supply can
be provided. The short term concentration was estimated based on sampling
results for the residential wells In which contamination has been detected.
The average dally Intake was then calculated to account for the four month
exposure. The estimated excess cancer risk associated with this short term
exposure Is less than one In a million.
\
The population at risk within the predicted plume Is divided Into three
areas: the area within City boundaries, the area within the Town of Flrcrest
boundaries, and the unincorporated area within Pierce County. Approximately
half of the predicted contaminant plume Is east of Orchard Street within the
Tacoma City limits. There are approximately 26 residences within the
projected plume. If contamination continues to flow predominately toward the
southwest. Groundwater sampling and hydrogeologlcal Investigations conducted
during the RI Indicate that the plume has reached the existing wells closest
to the landfill. Those with close-in wells In which contaminants have been
detected have been connected to City water.
There are still three close-in wells not hooked up to City water In which
contaminants have not been detected. No contaminants have been detected 1n
the distant wells, and based on the contaminant transport modeling. It will be
several years before the wells In this group will be Impacted as a result of
contaminant migration from the landfill.
23
-------
Table 5 lists the estimated landfill source concentrations for the seven
indicator chemicals listed in the RI and the estimated times to reach maximum
concentrations at the close-in and distant wells. The close-in wells would be
expected to be maximally Impacted by vinyl chloride beginning about 10 to 15
years from now while benzene would not be expected to peak until about 55 to
60 years hence. The distant wells would be expected to reach maximum benzene
concentrations In about 85 to 90 years.
There Is a possibility that if water from Leach Creek was used In the
future as a drinking water supply, exposure to vinyl chloride and/or benzene
at levels exceeding their MCLs could occur. There are existing water rights
for domestic use of Leach Creek.
Some potential exists for human exposure to contaminants by using private
well water for livestock and to water vegetables, etc. However,, since the
contaminant concentrations of the groundwater being used to water livestock
and Irrigate crops would be the same as detected in the private wells. It
would be highly unlikely that a significant exposure would result from this
pathway.
Environmental Evaluation
The Endangerment Assessment In the RI did not compare the levels of
organlcs and metals In the groundwater to ambient Water Quality Criteria (WQC)
for the protection of aquatic life. Metals and organic compounds in the
groundwater which are above federal or state WQC are of environmental
concern. Maximum concentrations detected In either on-site or off-site
24
-------
TABLES
TRAVEL TIMES TO REACH MAXIMUM AND THRESHOLD
CONCENTRATIONS, CLOSE-IN AND DISTANT WELLS
Indicator Chralcal
Vinyl Chloride(1)
Benzene (1)
1,2-Dlchloro« than*(I)
Mathylene Chlorlde(l)
1,l-Dlchlo roc thane(2)
Chlo roe than* ( 2)
Toluene(2)
Predicted
Offslte
Cone.
ug/L
60-70
3-10
4-5
150-160
30
30
30
Tlaa from Present
to Approach Max.
Concentration, Trs.
Clo««-Ia Distant
Veils Veils
10-15
55-60
45-50
5-10
35-40
5-10
55-60
25-30
85-90
75-30
20-30
65-70
20-25
85-90
Threshold
Cone.
ug/L
2
5
5
36,
271.
5
27
(V.ry High)
2000
Tla« From
Pr«a«nt to
Back B«lov
Threshold
Trs
>100
>100
SA
>100
HA, >100
HA
NA
HOTZS:
(1) Maxiaoa conccntratlona for carcloogena art aazlaua 70 years av«raf«.
(2) K*rt*nm concentratlooa for noncarclnogeoa are «a-rf«T» 90 day» a-rerage.
-------
groundwater for cadmium, chromium, copper, nickel and zinc, all exceeded
ambient WCC for the protection of aquatic life. An overview of the VOCs which
were identified as potentially harmful to the environment are listed in Table
3.
Flett and Leach Creeks support anadromous salmonid runs, which will be at
risk If toxic compounds are present in the creeks during critical phases
(e.g., smelting) In their growth cycles. Heavy metals, as well as certain of
the organlcs such, as xylene may also pose problems for the health of the
downstream wetlands ecosystem as the Leach Creek drainage ultimately enters
Puget Sound. This would most markedly impact highly vulnerable organisms such
as larval fishes, but parts of the commercially Important benthos (shellfish)
could also become adversely affected.
Conclusions
Based on a review of the endangerment assessment and data presented In
the RI report, the following conclusions were made concerning risk to human
health and the environment from contaminants associated with the Tacoma
Landfill site:
o Concentrations of several Indicator chemicals frequently exceed MCLs
In the groundwater- Drinking the water from contaminated wells
poses the most significant risk to human health, especially In terms
of chemicals In the aggregate.
25
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o Under the.no action alternative, some contaminant concentrations In
the groundwater plume are predicted to exceed ambient WQC when the
plume discharges to Leach Creek. These levels could pose a risk to
aquatic biota, especially since the Leach and Flett Creeks wetland
area enters Puget Sound.
o Based on EPA and Ecology's review of the Endangerment Assessment In
the RI, the agencies agreed that It would be appropriate, for the
protection of public health, to establish health-based levels for a
larger number of compounds than the seven Indicator chemicals
selected during the risk assessment. Accordingly, xylenes.
X
1,1,1-trlchloroethane and ethyl benzene have been added to the list
of contaminants of concern.
o Depending on the discharge location, performance levels for the
selected remedy will be based on MCLs, Water Quality Criteria, or
pre-treatment standards. In the absence of established standards or
Hater Quality Criteria, EPA Region 10 has conducted a risk
assessment of the compounds. These are listed 1n Table 8 of the
Selected Remedy portion of this document. The most stringent number
will be used for the performance levels for the treatment system If
the cleaned water Is discharged to surface water. For the other
volatile organic chemicals and metals found In the groundwater, EPA
and Ecology have identified a methodology for establishing
performance levels. This methodology 1s detailed In the Selected
Remedial Alternative section of this document (Section VI).
26
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V. SU« OF ALTERNATIVES EVALUATION
A. Identification and Screening of Remedial Technologies
In order to develop a complete listing of potential remedial technolo-
gies, general response actions corresponding to each contaminant pathway were
Identified.
The general response actions fall Into the following seven primary
categories:
o No action
o Institutional controls
o Containment
o Removal
o On-slte treatment/discharge
o Off-site treatment/disposal
o Other management options.
/
Forty potential remedial technologies for cor. ;rol ling contaminant
migration were screened. Thirty-one potential remedial technologies were
Identified for the groundwater pathway and nine potential remedial
technologies were Identified for the gas migration/air quality pathway. The
potential remedial technologies were categorized according to the appropriate
general response action. A screening process was applied to these to Identify
unsatisfactory technologies. Screening criteria were effectiveness,
Implementabl 11 tyVand cost.
27
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The technologies that were not screened out were assembled Into
preliminary remedial action alternatives. These alternatives were designed to'
meet the categories identified by the National Contingency Plan
-------
Institutional concerns. Requirements of the NC? were met by evaluating each
alternative with respect to the following criteria:
o Technical Feasibility
o Public Health Impacts
o Environmental Impacts
o Institutional Requirements
o Cost Analysis.
This analysis facilitates the comparison of similar components among the
alternatives for the same criteria.
Technical Feasibility
The technical evaluation considered the performance, reliability,
Implementabl11ty, and safety factors of the remedial actions. Performance of
each alternative was based on the alternative's expected effectiveness and Its
useful life. Key considerations In evaluating reliability Included operation
and maintenance (O&M) requirements and the demonstrated performance of the
technologies at similar sites. While SARA requirements do not Include
demonstrated performance, the six final remedial alternatives evaluated
against this criteria were known technologies. For Implementablllty. both the
constructablllty and the time required to achieve a given level of response
were considered. Constructablllty addresses whether the alternative can be
constructed on the site and the Impact of external conditions on the
construction. The.time It takes to Implement an alternative and the time to
29
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achieve beneficial results that attain or exceed relevant or applicable
standards were also considered. The safety evaluation considers short-term
and long-terra threats to the safety of nearby residents and to persons working
on-s1te. Major risks to consider are exposure to hazardous substances, fire,
and explosion due to activities conducted during Implementation of the
remedial action.
jc Health Impacts
The public health evaluation of alternatives assesses the extent to which
\
each alternative mitigates long or short-term exposure to any residual
contamination and protects public health during and after completion of the
remedial action. In evaluating both long and short-term public health
Impacts, two primary areas were considered. Evaluation of short-term Impacts
considered health effects on workers during construction of the remedial
action and on the public for the Interim period prior to remedial action
Implementation. Long-term Impacts were judged based on chronic Intake of the
contaminant over a lifetime.
Impacts
Each remedial alternative was evaluated for beneficial and adverse
environmental Impacts for the long and short-term. Criteria for evaluating
beneficial effects were final environmental conditions. Improvements In the
30
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biological environment, and improvements in resources people use. Criteria
for evaluating adverse effects were the expected effect of the remedial action
and the measures taken in the event Inevitable or Irreversible effects occur.
Institutional Requirements
Institutional requirements are divided into three categories: community
concerns, conformance with Applicable or Relevant and Appropriate Requirements
(ARARs). and permitting requirements. Community concerns addresses the
public's acceptance of the selected remedial action alternatives. The
N
remedial action alternatives developed In the FS should address all legally
applicable or relevant and appropriate standards, requirements, criteria, or
limitations to be consistent with SARA. Institutional constraints are those
mechanisms available to ensure administrative control over activities at the
site (zoning, permits, ordinances, etc.).
Cost Analysis
Detailed cost analysis of alternatives Involves estimating the expendi-
tures required to complete each measure In terms of capital costs, and annual
operation and maintenance costs for a 30-year period. Once these values were
determined and a present worth calculated for each alternative, a comparative
evaluation was made. The cost estimates presented In the FS section were
based on conceptual designs prepared for the alternatives (I.e., without
detailed engineering data). These estimates were accurate between +50 percent
and -30 percent In 1987 dollars.
31
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Rating Alternatives
A rating system Is used to evaluate alternatives, and the terms high,
moderate, and low are assigned to each. A high rating Indicates that the
alternative promotes the Intent of the criterion and/or meets or exceeds the
remedial objectives. A moderate rating indicates that the alternative only
partially promotes the intent of the criterion; however, the alternative does
remediate the problem to an acceptable extent even though It does not meet all
the remedial objectives. A low rating Indicates that the alternative does not
promote the criterion and/or does not meet the remedial objectives.
\
An evaluation of each alternative Is contained In Tables 6 and 7. These
evaluations are based on numerical ratings of each criterion contained In the
FS (Black & Veatch 1987). A criterion was subdivided Into one or a few
factors, which were rated from 1 to 5. To establish the criterion numerical
rate, numerals assigned to each factor within the criterion were averaged.
For this report, ratings were assigned as follows:
Numerical Rating New Criterion Rating
£2.00 High
2.01-3.99 Moderate
>4.00 Low
32
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TABLE 6
SUMMARY OF DETAILED EVALUATION OF REMEDIAL ALTERNATIVES
No.
,
2
Cost
Alternative (No. In (S) Capital
No Actlonjl)
Alternative Water Supply/
Landfill Cap (J) 16.423
($1.000)
Present
Worth
--
IB',376
Public
Health Impacts
LOM
High
Environmental
(•pacts
LOM
Moderate
Criterion
Technical
Feasibility
N/A
High
Institutional
Requirements
LOM
High
Community
Concerns
LOM
High
Pump. Treatment, and
Discharge with Landfill Cap
a. Off-site Treatment at
Sewage Treatment
Plant (2)
b. On-slte Treatment (Air
Stripping and Carbon
Adsorption (4)
*
c. On-slte Treatment
Carbon Adsorption (8)
d. On-slte Treatment
(Air Stripping) (I?)
17.91?
23,418
High
High
Moderate
High
High
19.532
19.266
18.971
22,717
23.417
21.015
High
High
High
High
High
High
Moderate
Moderate
Moderate
High
High
High
High
High
High
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TA8LE 7
SECTION 121(b) (1) (A-fi) FACTORS
—
Criterion 1
Compliance with ARABS Low
Reduction of To*1dty.
Mobility. volune Lo«
Short-Term Effectiveness Low
Long-Tern effectiveness Low
Implement ability N/A
Cost (See Table 6)
Comnunlty Acceptance Low
State Acceptance Low
Alternative
2 3a
\
Moderate High
Moderate High
High Moderate
Moderate High
High Moderate
Moderate High
Moderate High
3b
High
High
Moderate
High
Moderate
High
High
JC
High
High
Moderate
High
Moderate
High
High
Id
High
High
Moderate
High
Moderatt
High
Moderate
Overall Protection of
HUMUI Health and the
Environment
Low
Moderate High
High
High
High
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C. Results of Detailed Evaluation of Remedial Alternatives
This section presents a summary of the detailed evaluation of the
remedial alternatives In terms of costs, public health Impacts, environmental
Impacts, technical feasibility, institutional requirements, and community
concerns. A summary of these Items Is presented in Table 6 according to 1985
RI/FS Guidance Factors (EPA 1985) and an evaluation of the remedial
alternatives according to the Section 121(b)(l)(A-G) factors is shown In
Table 7.
Non-cost Evaluation
As shown In Table 6. Alternatives 2, 3a. 3b, 3c. and 3d all had four high
ratings and one moderate rating. Therefore, they would be Judged comparable
alternatives under this system of rating criteria. However, evaluating
alternatives using guidance from Section 121
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Cost Summary and Sensitivity Analysis
Cost estimates prepared for each alternative Involved approximation,
assumptions, estimations. Interpretations, and engineering Judgment. To
provide some Indication of sensitivity of the costs to changes In key
parameters, a sensitivity analysis was performed.
The cost of closing the landfill Is the major cost for all the
alternatives under consideration, and Is the same for each. The treatment
process cost could be-the most variable because alternatives would not yield
the same Influent concentrations. To evaluate the Impact that changes in
concentration would have on carbon adsorption treatment costs, concentrations
of two and three times the predicted value were analyzed. The carbon
adsorption unit cost was chosen for analysis on the basis of Its potential
Impact on overall treatment cost estimates of Alternatives 3b and 3c. When
the concentration of contaminants In the waste stream Is doubled, the carbon
usage (cost) will Increase by approximately 1.5 times. The total cost for
Alternative 3b would Increase 3.8 percent while the total cost for Alternative
3c would Increase 6.8 percent. For the case when the contaminant
concentrations are tripled, the carbon cost will approximately double. The
total cost for Alternative 3b would Increase 7.3 percent while the total cost
for Alternative 3c would Increase 9.7 percent.
34
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VI. SELECTED REMEDIAL ALTERATIVE (No. 3)
A. Description of Selected Remedy
The selected remedy Includes a landfill cap and gas extraction system to
control the source, and a ground water extraction and treatment system to
control migration of the plume. All extracted water will be treated to
specific performance standards, monitored to ensure compliance and will be
properly discharged. The Tacoma water supply system will be expanded to
assure sufficient water Is available should any water supply (public or
private) become contaminated from the landfMl. The remedy also Includes a
closure schedule for operation of the landfill.
The remedy Is designed to:
o Prevent further migration of the plume via the ground water
extraction-treatment system.
/
o Reduce the production of leachate by placing constraints on site
operations and by properly grading and capping the landfill.
o Eliminate off-site gas migration through the gas extraction system.
o Further protect public health and the environment via monitoring of
groundwater, surface water, gas probes, air emissions, and
provision of alternate water supplies where necessary.
35
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Management of Migration
Migration control will be achieved through a ground water extraction and
treatment system, and a system or method to confirm performance. Activities
necessary to develop those systems shall be conducted during remedial design.
Hells for this system will be placed within and. If necessary, downgradlent to
contain the plume. Containment Is defined as controlling the plume and
preventing the spread of contamination. The goal of the containment system is
to prevent any further degradation of existing water quality beyond the
boundaries of the existing plume. The extraction wells should be designed to
achieve this objective. The existence of the gradient reversal due to pumping
N
by the city of Tacoma well field, local effects from pumping the Fircrest
wells, or monitoring results at the landfill may result In the need for
extraction wells at locations other than those Identified In the feasibility
study. Minimum flows as required by WAC 173-512 shall be maintained In Leach
and Flett Creeks.
The treatment process shall be permanent and shall effectively reduce the
toxlclty. mobility, and volume of contaminants. It shall also employ all
known, available, and reasonable methods to treat the contaminated ground
water, and to prevent the spread of contamination. Discharge of treated
ground water may be to either Leach Creek, Flett Creek, or the sanitary sewer.
If the discharge Is to either Leach Creek or Flett Creek, the effluent
must meet or exceed maximum contaminant levels (MCLs) developed pursuant to
the Safe Drinking Hater Act or meet the chronic fresh water criteria as set
forth In EPA's Quality Criteria for Hater. 1986 (EPA 440/5-86-001). whichever
36
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is more stringent. Both of these creeks have existing water rights en them,
although they are closed to further appropriation by MAC 173-512. In
addition, both creeks support anadromous salmonid runs.
*
Most of the contaminants found at the Tacoma Landfill do not currently
have MCLs. For the VOCs listed in Table 3, and for metals in the groundwater,
which EPA and Ecology have not established treatment levels, a methodology for
determining the appropriate discharge limits has been established. If no MCL
has been established for a contaminant, the ambient water quality criteria
(HQC) for protection of human health for water and fish ingestlon will be
used. If the value for protection of fish (the chronic fresh water criteria)
X
Is lower than the value for protection of human health, the lower value will
be applied. If there are no WQC at all, then additional guidance documents,
such as Health Advisories from EPA's Office of Drinking Hater or any
appropriate toxlcologlcal profiles, will be used to develop treatment levels.
These treatment levels must be reviewed and approved by both Ecology and EPA
prior to their use. This methodology will be used to set performance levels
for any other contaminants Identified In the groundwater and traceable to the
landfill.
For six of the volatile organic compounds listed In Table 8. appropriate
treatment levels have been Identified. These are based on Safe Drinking Hater
Act MCLs or ambient HQC. In the absence of an MCL or ambient HQC, EPA Region
10 conducted a risk assessment of the chemical and provided an appropriate
treatment goal for the protection of public health, welfare and the
environment. These goals are listed In column three of Table 8 and will be
-»
used as performance goals for the treatment system. In addition, the effluent
37
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TABLES
PERFORMANCE LEVELS FOR TREATMENT SYSTEM
DISCHARGE TO SURFACE WATER
TACOMA LANDFILL
(ug/L)
Constituent
Benzene
Chloroethane
1 ,1-dlchloroethane
1 ,2-dlchlorcethane
Ethyl benzene
Methylene chloride
Toluene
1 ,1 ,1-trlchloroethane
Vinyl chloride
Xylenes
Safe
Drinking
Hater Act
MCL
5
5
200
2
Water Qual i
Hater and(l)
Fish
0.66*
s
0.94*
1.400
14
18.400
tv Criteria
Chron1c<2)
Fresh water
53
20.000
320
175
EPA
Req. 10
R1sk<3)
Assess.
20
20
5*
10
(1) EPA Quality Criteria for Hater, 1986 EPA 440/5-86-001. for water and
fish Ingestlon by humans.
(2) Chronic fresh water criteria for protection of aquatic life.
Where no values for chronic exposure were available, the acute
values were divided by 100.
(3) Based on EPA Region 10 Risk Assessment.
• Values presented for carcinogens are at the 10~6 risk level.
-------
must meet water quality standards as set forth In 173-201 (Water Quality
Standards for Haters of the State of Washington).
If the option of discharge to the sanitary sewer Is chosen, it must be
consistent with discharge limitations as defined by HAG 173-216 (State Waste
Discharge Program) and must meet pre-treatment regulations (City of Tacoma
Code, Chapter 12.08). as revised for operation of the secondary sewage
treatment plant.
Any treatment system which results in contaminant air emissions shall be
designed to address appropriate ambient air quality values as determined by
Ecology's Draft New Source Review Guidelines for Toxic Air Contaminants.
(September 1986, or as revised). In addition, the Puget Sound Air Pollution
Control Authority (PSAPCA) has made the determination that all new sources
shall use Best Available Control Technology (BACT). This also will be a
requirement of the treatment system design. BACT may Involve a different
technology for different contaminants.
The extraction and treatment system can be shut off when water quality
within the plume, outside the compliance boundary (defined by WAC 173-304 as
the edge of the filled area), consistently meets or exceeds drinking water
standards, or previously established and approved health-based criteria. In
addition to meeting health-based criteria, potential impacts to public and
private water supplies and to Leach Creek must be considered In the decision
to shut off the system. Ecology and EPA will reevaluate the Implemented
system every five years to assure that It Is working properly and to propose
any modifications'that could facilitate the cleanup of the groundwater.
38
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Source Control
Source control measures consist of constructing a cap on the landfill to
minimize Infiltration and maximize run-off. Unllned areas of the landfill
will be capped as soon as possible. WAC 173-304 defines the minimum
requirements for a cap on a municipal landfill. A more stringent cap will be
required unless further analysis of the cap, to be provided during remedial
design, shows that a significant reduction In leachate volume or toxlcity
would not be achieved.
Increased run-off due to the construction of the cap will be routed off
\
the landfill to reduce infiltration. The slope of the cap and construction of
drainage structures will be consistent with HAC 173-304. The run-off collected
from the landfill will be directed to the appropriate storm or sanitary
sewers, consistent with local storm drainage ordinances or pre-treatmerit
regulations. The storm drainage plan, prepared as part of the remedial
design, will determine and minimize any downstream Increases In peak flow.
The Minimum Functional Standards (MFS) (HAC 173-304) prohibit filling In
unllned areas after November 1989. These standards contain specific liner
requirements which will apply to all municipal landfills by this date.
Compliance with Minimum Functional Standards Is determined by TPCHD, In
accordance with Ecology review. Insufficient Information has been received by
Ecology and TPCHD to evaluate compliance of the liner Installation with
Minimum Functional Standard requirements. If the liner Is determined not to
be In compliance, a variance will be required from TPCHO to operate the
Central Area PltT
39
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In the interi.Ti, the City has identified several unlined areas which need
to be filled to meet minimum slope requirements in WAC 173-304. Additional
filling In these areas will be kept to the minimum required to meet the final
grade requirements of the Minimum Functional Standards. The City plans to
develop an unfilled area of the landfill (North Borrow Pit) for future waste
disposal. Filling of this or other previously unused areas will require a
liner consistent with WAC 173-304.
Should a variance be needed and granted, the Central Area Pit will be
brought up to final grade in accordance with the Operations and Closure Plan
to minimize leachate production. Leachate head wells will be Installed in the
waste In the Central Area to assure that the leachate head requirements of MAC
173-304 are being met. Ecology and EPA will identify and approve of the
appropriate number of leachate head wells during the Remedial Design phase.
MFS requires operating landfills to submit an operating plan by October
1987. A schedule for closure of the landfill under WAC 173-304 Is considered
part of the remedial action at this site. The schedule, developed as part of
the required Operations and Closure Plan, will address various waste reduction
measures and develop contingency plans If these measures do not produce the
expected results. The contingency plans will Include specific dates for
beginning the process to site another municipal solid waste disposal facility
to serve the City of Tacoma. Haste reduction measures to be considered
Include, but are not limited to:
o Increased recycling Including a program to exclude hazardous waste
from the landfill
40
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o Incineration of the light fraction of shredded waste at the Tacoma
City Light Cogeneraticn plant
o pyrolysls of the heavy fraction of shredded waste at an on-s1te
facility
Several utilities pass through the site. The Operations and Closure Plan
will provide for rerouting these utilities around the site or developing a
testing and maintenance program that will ensure their long-term Integrity
without Interfering with the selected remedy.
^
The production of methane gas at the landfill Is being addressed through
the Installation of a gas extraction system and is being monitored using a
series of gas probes Installed around the landfill. The gas collected by the
extraction system 1s burned by the combusters. which meet PSAPCA's BACT
requirements. Any future expansion of this system will be required to comply
with these requirements. Additional gas probes will be Installed In the
surrounding neighborhoods to verify that the extraction system Is preventing
off-site gas migration. If significant concentrations of gas are found In the
soils off-site, further gas extraction wells may have to be Installed to
collect and'control these methane sources.
Because landfill gas Is warmer than the ambient air. condensate collects
In the gas collection line. This condensate Is currently allowed to drain
back Into the landfill Condensate from the flare station Is collected and
discharged to the sanitary sewer. As part of the remedial design, the
41
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quantity and quality of these condensates will be determined. If significant
concentrations or volume of condensates are found, the condensate shall be
collected and treated appropriately. Source monitoring of the gas burners and
the treatment plant system will be required.
Monitoring
Ground water monitoring wells shall be Installed In locations appropriate,
for obtaining the following information:
o determine if the ground water extraction system Is preventing the
spread of the contaminant plume
o determine the extent of plume migration to the east of the site
o Identify any potential Impacts to Leach Creek and the Flrcrest well
system
o ensure there Is no dense phase plume migrating away from the site In
the deepest zones of the aquifer.
Ecology and EPA will review and approve of the number and location of the
groundwater monitoring wells during the Remedial Design phase of the cleanup
program.
Leach Creek will be monitored for both water quality and quantity. Other
surface waters acting as receiving waters for either the groundwater
42
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extraction system or the surface drainage system will be monitored for water
quality. Effluent from the treatment system will also be monitored to assure
that discharge limitations are not exceeded. The nature and extent of the
monitoring program. Including bloassays, will be developed during the Remedial
Design phase of the cleanup program.
At a minimum, the private wells In the path of the plume will continue to
be monitored on a quarterly basis. Flrcrest wells will be sampled monthly.
Any well, public or private, which becomes contaminated due to the landfill
will be replaced and water will be supplied from existing City of Taccma water
supply systems. If EPA and Ecology make a determination that any well is in
\
danger of exceeding an MCL. or a contaminant level based on an EPA risk
assessment, connection to Tacoma's municipal water supply will be required.
Aesthetic quality will also be a consideration In making this determination.
Tacoma, In cooperation with the Town of Flrcrest, and Pierce County, will
pursue the establishment of an ordinance, or other suitable methodology, to
restrict drilling of water supply wells In an area from Tyler Street to Leach
Creek; and from Center Street to approximately South 56th Street.
B. Statutory Determinations
The selected remedy meets all statutory requirements for the overall
protection of human health and the environment. The groundwater extraction
system will remove contaminated groundwater migrating from the landfill and
prevent contamination from spreading In the aquifer. The movement of
contamination to nearby Leach Creek should be prevented by groundwater
-------
pumping. Treatment of the extracted water will be designed to reduce the
toxlclty, mobility and volume of contaminants and prevent them from returning
to the groundwater or surface water environment. Nearby residents affected by
contaminated groundwater, or by low water volume or flow as a result of the
operation of the extraction-treatment system, will be connected to Tacoma's
municipal water system.
The selected remedy must also meet all Applicable or Relevant and
Appropriate Requirements (ARARs) and should address those items listed In the
To Be Considered category. These are listed and their application Is briefly
described In Attachment A.
The laws and regulations of concern include but are not limited to the
following:
1. Resource Conservation and Recovery Act (RCRA; 42 USC 6901), RCRA
regulations (40 CFR 261 to 280). Washington State Dangerous Haste
Regulations (MAC 173-303 and 70.105 RCW). and Washington State
Minimal Functional Standards for Solid Haste Handling (HAC 173-304
and 70.95 RCH).
Groundwater protection requirements of RCRA and Hashlngton
State Dangerous Haste Regulations will be attained by
Installation of the landfill cap to minimize leachate
production, and operation of the groundwater extraction wells
to remove contaminated groundwater. The selected remedy
prevents further spread of groundwater contamination and
44
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constitutes a Corrective Action Program as specified in 40 CFR
264.100 and MAC 173-303-645(11). Closure of the Tacoma
Landfill to State Minimum Functional Standards will be
evaluated to ensure consistency with RCRA landfill closure
standards.
2. Safe Drinking Water Act (42 USC 300). and Primary Drinking Hater
Standards (40 CFR 141).
Groundwater will meet maximum contamination levels (MCLs) and
N
appropriate health-based standards as the contaminated plume Is
removed and leachate generation Is minimized. The selected
remedy will prevent exposing the public to contaminated
drinking water by monitoring residential wells for MCLs and
connecting the house to Tacoma's municipal water supply when
conditions require It. Any affected public water supplies also
will be connected to dty water. Therefore, by monitoring,
providing an alternate drinking water supply, and restricting
groundwater use (until the aquifer no longer exceeds these
levels) In the area, the selected remedy will meet the
requirements of these regulations.
45
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3. C'.ean Air Act (72 USC 7401).
If an airstrlpping system is used, concentrations of
contaminants in the air stripper off-gases will be required to
meet the requirements of the Clean Air Act. The flares for the
methane gas extraction system must also.meet the requirements
of the Clean Air Act.
4. Clean Water .Act (33 USC 1251), National Pollution Discharge
Elimination System (NPOES; 40 CFR 122). NPDES Permit Program (HAC
173-220), and Water Pollution Control Act (RCW 90-48).
The selected remedy treats the extracted water to meet MCLs,
health-based standards, or Hater Quality Criteria prior to
discharge. Therefore, there will be no adverse Impact on
surface waters resulting from discharge of treated groundwater,
and the requirements of these regulations will be attained.
The landfill cap will reduce leachate generation and therefore
reduce the Impact on groundwater. Storm drainage will be
collected and discharged either to existing storm sewers or to
surface waters. Contaminated storm water runoff will meet
pre-treatment regulations and will be discharged to the
sanitary sewer. Groundwater extraction and treatment will
further reduce the contaminant plume. Other substantive
aspects of the NPOES Permit System will be met during the
design phase, although no permit is actually required.
46
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Although on-site remedial work does not require a permit, the
substantive requirements of any applicable permit will be met.
Federal, state, or local permits which are required for
off-site activities will be obtained.
5. Rules and Regulations of the State Board of Health Regarding Public
Water Systems (MAC 248-54).
The selected remedy provides standards for connection to an
alternative drinking water supply for all residents who require
\
these supplies In conformance with these regulations.
6. Protection of Withdrawal Facilities Associated with Groundwater
Rights (WAC 173-150).
This regulation protects water rights both In terms of water
quality and quantity. Groundwater quality will reach levels
less than MCLs; therefore the selected remedy complies with
that portion of the regulation. The other portion of the
regulation requires that surrounding wells not be deprived of
their water supply due to other groundwater removal actions.
Alternative water supplies will be made available to all
residents affected by groundwater removal actions to meet the
requirements of this regulation.
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7. Minimum Functional Standards for Landfills (HAC 173-314 and 70.95
RCW).
The technology to be applied to remediate the landfill at a
minimum will meet the Washington state standards for ongoing
landfill operations, closure, capping, leachate containment,
and methane control.
8. Hazardous Haste Cleanup Act (70.1058 RCW).
\
The selected remedy will be the cleanup standards established
by this act.
The selected remedy meets the SARA preference for permanent solutions to
the maximum extent practicable. Treatment technologies are used as a
principal element of the remedy and they will effectively reduce the toxlclty,
mobility, and volume of the contaminants permanently. Connection of
residents, as required, to the Tacoma municipal water water supply Is also
considered a long-term solution.
*
The selected remedy meets all objectives of remedial action 1n that It
provides a safe water supply and therefore protects public health, provides a
permanent solution with moderately frequent maintenance, protects the
environment to the maximum extent practicable, and reduces toxlclty, mobility,
or volume as a principle element of treatment. The selected remedy meets the
requirement of cost-effectiveness.
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VII. ENFORCEMENT
On June 27, 1986, Tacoma assumed responsibility for conducting the RI/FS
under a Response Order on Consent Issued by Ecology. The-remedial action Is
anticipated to be accomplished voluntarily by the responsible parties. EPA
and Ecology Intend to start a negotiation period after the signing of the
Record of Decision and will ensure that the remedial action proceeds.
Finally, EPA and Ecology are still considering the possibility of Identifying
additional parties who may be potentially responsible for conditions at the
site. Other than the June 27, 1986 Consent Order, there has never been any
enforcement action taken by the regulatory agencies (I.e., EPA or Ecology)
regarding the Tacoma Landfill site. If the responsible parties decline to
Implement the selected remedy as described in the Record of Decision, however,
EPA and Ecology will seek appropriate enforcement action.
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VIII COMITY RELATIONS
Community relations activities conducted at the Tacoma Landfill site to
date Include the following:
o In 1983. the Taccma landfill was included as part of the South
Tacoma Channel site on the National Priorities List under
Comprehensive Environmental Response. Compensation, and Liability
Act of 1980 (CERCLA).
o In Hay 1985. Ecology and Black & Veatch began Remedial Investigation
(RI) Phase I.
o In December 1985, Ecology and Black & Veatch began Implementing thu
RI Project Work Plan and Sampling Plan Phase I.
o In 1985, a community relations plan was developed by Black & Veatch
and Hall and Associates for Ecology.
o From May 1985 to the present, the City of Tacoma maintained
correspondence with Interested local residents and well owners by
providing notification of quarterly sampling and outlining
analytical results.
o In May 1986. the City of Tacoma Issued a fact sheet discussing
management of methane gas at the landfill.
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o On May 13. 1986, U.S. EPA, In cooperation with the City of Tacoma
and Ecology, conducted a public meeting to discuss well water
quality of private wells surrounding the landfill.
o In July 1936. the City of Tacoma issued a press release and letter
to residents discussing background and scope of the RI.
o In July 1986. the City of Tacoma and Ecology signed a consent
agreement establishing guidelines for the RI/FS.
o In August 1986, the City of Tacoma began sampling 13 private wells
located near the landfill.
o In February 1987. the Phase I Sampling Plan, Phase II Sampling Plan
and. Phase I RI Report were completed and made available to the
public through Taccma City and County libraries.
o On April 16, 1987, Ecology, In cooperation with the City of Tacoma
and EPA , conducted a public meeting and provided a fact sheet
discussing progress of the RI/FS.
o In January. 1988 a public notice was published in the Tacoma News
Tribune announcing the availability of the RI and FS Reports and a
public meeting to be held February 11. 1988.
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o On February 11,1988, Ecology, in cooperation with EPA and the City
of Tacoma, conducted a public meeting to discuss alternatives for
cleaning up the groundwater and controlling methane gas at the
landfill. Including the agencies'-preferred plan.
o From February 4 through March 4. 1988, public comments on the RI/FS
were accepted and documented.
o In February and March 1988 the the Responsiveness Summary and Record
of Decision were written.
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APPENDIX A
APPLICABLE OR RELEVANT AND APPROPRIATE REPEKXTS
A. FEDERAL LAWS AND REGULATIONS
\
o Resource Conservation and Recovery Act (RCRA) (42 USC 6901),
Subtitle C:
\
Protection of groundwater (40 CFR 264, Subpart F) Closure and
post-closure of landfills (40 CFR 264. Subpart G) [Note: These
are administered by Ecology under Dangerous Haste Regulations,
HAC 173-303]
o Safe Drinking Hater Act (SWOH) (42 USC 300):
Drinking Hater Standards (40 CFR 141). Enforceable Maximum
Contaminant Levels (MCLs), Hhlch are relevant and appropriate
at this site. [NOTE: This Is administered by the Department of
Social and Health Services under HAC 248-54-175 for public
water supplies]
o Clean Hater Act (CHA) (33 USC 1251):
national Pollutant Discharge Elimination System (NPOES) (40 CFR
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122) [Note: NPDES program is administered by Ecology under WAC
1-73-220]
Hater Quality Criteria (EPA440/5-86-001).
o Clean Air Act (CAA) (72 USC 7401):
National Emission Standards for Hazardous Air Pollutants
(NESHAPS) [Mote: NESHAPS Program is administered by Ecology
and Puget Sound Air Pollution Control Agency under MAC 173-403].
\4
O OSHA 29 CFR 1910:
governs worker safety at hazardous waste sites
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B. WASHINGTON STATE LAWS AND REGULATIONS
o Dangerous Haste Regulations, MAC 173-303: established standards for
handling and disposal of hazardous waste.
o Minimum Functional Standards for Solid Haste Handling, 70.95 RCW and
HAC 173-304: requirements for operation and closure of solid waste
disposal facilities.
o Hazardous Waste Cleanup, Chapter 70.1058 RCW: standards for the
cleanup of hazardous waste s1tes.x
o Hater Quality Standards for Waters of the State of Hashlngton, HAC
173-201: Standards for discharge to Flett Creek, or Leach Creek, or
-» • • •
•V " •
surface waters of the state.
o Submission of Plans and Reports for Construction of Hastewater
Facilities, WAC 173-240: standards for the design, operation and
/
maintenance of waste water treatment systems.
o National Pollutant Discharge Elimination System Permit Program, HAC
173-220: Discharge limitations If treated water Is discharged Into
surface waters.
o Underground Injection Control Program, WAC 173-218: discharge
standards for reinjectlon of treated water Into the ground.
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o State Haste Discharge Permit Program, WAC 173-216: Standards for
the discharge to the sanitary sewer or groundwater (except by
Injection).
o Hashlngton Clear Air Act, RCH 70.94: applicable for discharging
pollutants Into the atmosphere from a new source.
o General Regulations for Air Pollution Sources, WAC 173-400.
o Implementation of Regulations for Air Contaminant Sources, WAC
173-403. '
o Emission Standards and Controls for Sources Emitting Volatile
Organic Compounds. HAC 173-490.
o Instream Resources Protection Program - Chambers-Clover Creeks
Basin, HAC 173-512: governs minimum water flow and levels
requirements.
o Protection Associated with Groundwater Rights, WAC 173-150-100:
applicable to activities that would degrade water quality.
o Minimum Standards for Construction and Maintenance of Hater Hells,
WAC 173-160: governs design of extraction and monitoring wells.
o Water Hell Construction Act, RCH 18.104: provides for the
regulation of water well construction.
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o Hater Pollution Control Act, RCH 90.48: standards for the
protection of surface water and groundwater.
o Management of Haters of the State. RCW 90.54.020: provides for the
protection of state water quality.
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TO BE CONSIDERED
o Ecology New Source Review Guidelines for Toxic Air Contaminants In
the State of Washington, September 1986.
o EPA Policy Statement - Groundwater Protection Strategy.
o Washington Department of Ecology Final Cleanup Policy: (Technical
memorandum dated July 10, 1984) used for guidance In establishing
cleanup levels.
V
0 State Hater Code. RCH 90.03 and Hater Rights. RCH 90.14: estab-
lishes water rights permits necessary for water withdrawals.
Including groundwater extraction.
o State Environmental Policy Act (SEPA). HAC 197-11: covers all
actions which may have significant environmental Impact.
o State Protection of Upper Aquifer Zones. HAC 173-154: restricts
activities that would Impair senior groundwater rights. Including
water level lowering, and water quality degradation.
o Protection of HUMrawal Facilities Associated with Groundwater
Rights, WAC 173-150: restricts activities that would Impair senior
groundwater rights. Including water levels lowering and water
qualIty degradation.
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o City of Tacoma Code, Chapter 12.08: pre-treatment regulations whicl:
govern 'discharge to the sanitary sewer.
o Pierce County Storm Drainage Ordinance 86-60: provides guidelines
for the report criteria, analysis and design of public and private
storm drainage systems.
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APPENDIX 8
RESPONSIVENESS SUMMARY
This community relations responsiveness summary Is divided Into the
following sections:
Section 1.0 Overview. This section reviews the U.S. Environmental
Protection Agency s (EPA) preferred alternative for corrective
action, and likely public reaction to this alternative.
Section 2.0
Background on Community Involvement and Concerns. This section
provides a brief history of community Interest and concerns
raised during remedial planning activities at the Tacoma
Landfill site.
Section 3.0
Summary of Major Comments Received During the Public Comment
Period and Agency Responses to the Comments. Both written and
oral comments are categorized by relevant topics. EPA's
responses to these major comments are also provided.
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Section 4.0 Remaining Concerns. This section describes remaining community
concerns that EPA and Ecology should consider in conducting tn|
remedial design and remedial action at the Tacoma Landfill site.
Community relations activities conducted during remedial response
activities at the Taccma Landfill site are listed In Attachment A to this
summary.
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1.0 OVERVIEW
The City of Tacoma, under a Response Order on Consent Issued by the
Washington State Department of Ecology, completed a Remedial
Investigation/Feasibility Study (RI/FS) for the Tacoma Landfill site, located
south of Tacoma, Washington. From 1960 through the 1980s, the landfill has
received refuse and garbage from the city's collection service. Hazardous
materials were part of the refuse. Contaminants were discovered In nearby
drinking water wells at levels high enough to cause public health concerns.
The cleanup alternative recommended by Ecology to EPA, was to Intercept the
advance of contaminants by extracting the contaminated water, treating It. and
discharging the cleaned water. This alternative Is described In more detail
In the Feasibility Study (Chapter 4; Black & Veatch 1987) and In the Selected
Remedial Alternative section of the Record of Decision (Section VI).
In this summary, concerns of the local community about problems at the
site, the recommended cleanup alternative, and the study process Itself are
described. Public comment also Indicates that residents hope the cleanup will
be as quick and thorough as possible, and not raise additional problems
through Its Implementation. Only one potentially responsible party, the City
of Tacooa. has been Identified to date although an Investigation to Identify
others has been Initiated. The Identified responsible parties will share
cleanup costs. Residents are concerned about the funding to perform the
cleanup and any adverse Impact upon refuse collection rates.
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2.0 BACKGROUND ON COMMUNITY INVOLVEMENT AND CONCERNS
Community Interest in the Tacoma Landfill began as early as 1968 when
local residents complained of poor water quality In thel.r private wells. This
condition continued throughout the 1970s. The residents are currently
concerned about leachate from the landfill contaminating their private wells,
and methane gas entering their homes.
Early In the Remedial Investigation/Feasibility Study (RI/FS) process
(1985), Hall and Associates Interviewed local residents and government
officials and compiled a list of community concerns regarding the landfill.
The following Is a compilation of community concerns In 1985:
o Lack of Interest and unwillingness to provide water testing by the
public health agency.
o Lack of candor by government officials, particularly relating to
contamination of wells In University Place during the late 1970s.
o Quality of drinking water.
o Health of small children In the neighborhood and recent miscarriages.
o Cost of replacing private wells and connecting residences to the
city's water system.
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o Inconvenience associated with using bottled water
o Need to be kept informed of landfill related activities.
The City of Tacoma and Ecology developed a community relations plan In an
effort to keep the public Informed of RI/FS activities. The City of Tacoma
has addressed public concerns by holding meetings with residents to discuss
RI/FS activities and public health concerns. Attachment A summarizes the
community relations activities conducted at the South Tacoma Landfill. The
following is a record of those activities:
• ^
1) In 1968, the City of Tacoma Department of Public Works began
receiving complaints of contamination-of the Home Builder's Association well,
located at South 40th and Orchard Streets.
Actions; The City of Tacoma conducted a chemical analysis of the well
water. Results revealed the water contained a high Iron content, was
discolored, and had a slight odor. The city Installed a leachate
collection system comprised of a gravel drain and dike. The dike
diverted leachate flow to the drain that discharged to a perforated
manhole connected to the city sewer system. An additional cover placed
over the fill promoted surface water drainage, Inhibited Infiltration of
water, and reduced leachate production. The Home Builder's Association
was eventually connected to the city's water system.
2) In the late 1970s, wells owned by the University Place Water Company
located west of the landfill, were found to contain elevated levels of Iron
and manganese. Residents complained of unappealing water taste, color, and
odor-
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Actions: An Investigation conducted by Ecology Indicated that well
water contamination could have resulted from surface water or groundwater
froo the landfill, or from water migration through material containing
high levels of Iron and manganese. Residents served by these wells were
eventually connected to the city's water system and these wells have not
yet been abandoned in accordance with State requirements.
3) In 1985, prior to the RI, groundwater samples were collected from
wells near the landfill and analyzed for U.S. EPA priority pollutant volatile
organic compounds. Four private wells located In the vicinity of the landfill
were found to contain priority pollutant volatile organic compounds.
Actions: In June 1985, vinyl chloride was detected In the
Shaughnessy1s well and they were connected to the city's water system.
Vinyl chloride was detected In the Donaldson's well and they were
connected to the city's water system In June 1986. Although vinyl
chloride was not detected In the remaining two wells (those of the
Hlgglns/Knlpher and Miller residences), the city supplied these
residences with bottled water for drinking. The Hlgglns/Knlpher and
Miller residences were later connected to the city's water system In
October and December 1986. respectively. In 1987, the Meyer and Phillips
residences were connected to the city's water system because vinyl
chloride contaminated their wells.
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4) Early in 1986, local citizens were becoming concerned about the
quality of water from their private wells.
i
Actions: Ecology. In cooperation with the City of Tacoma and EPA.
conducted a public meeting on May 13. 1986 to discuss affects of
potential leachate migration to private wells. The meeting was open
exclusively to private well owners. Twenty citizens and ten city, state,
and federal representatives attended. At this time, Black & Veatch was
still acting as a consultant for Ecology. A description and history of
the site was outlined, the affects of methane gas migration were
discussed, and an _,enda and fact sheet were distributed.
5) In May 1986. local residents voiced concern about lateral methane
gas migration at the City of Tacoma municipal landfill.
Actions: The city hired a consultant (Mandeville Associates) to
Investigate gas production and the extent of off-site migration prior to
the release Incident. The city conducted field surveys using portable
exploslmeters and found methane gas had migrated beyond the landfill
boundaries. As a result of these findings, a gas extraction system
comprised of 128 gas extraction wells with gas probes at 66 locations was
Installed. Initial efforts focused on controlling gas In businesses
located southwest of the site. A flare static- with permanent flares was
Installed In November 1986. The city Implemented a gas monitoring
program for structures surrounding the landfill. Both ambient and point
sources were measured.
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6) As early as 1983. local residents were voicing concerns about
potential groundwater contamination from leachate migrating from the landfill.
Actions: In June 1986, the City of Tacoma, under the direction of
Ecology, assumed responsibility for conducting an RI/FS. Quarterly
groundwater monitoring activities were established to Identify hazardous
contaminants. The city continued contact with specific residents by
notifying them of sampling dates and reporting analytical results.
Public Involvement in landfill Issues Is maintained by Ecology conducting
public meetings and providing fact sheets on recent landfill activities
and studies.
7) As the RI progressed in 1987. local citizens continued to voice
concerns and questions.
Actions: Ecology, In cooperation with the City of Tacoma and EPA,
conducted a public meeting on April 16. 1987 to discuss the progress of
the RI/FS. Groundwater well monitoring procedures and analytic results
were addressed. At that time, three to four residences had been
connected to the city's water supply. Methane gas migration and
monitoring were discussed. Or. Branchflower, a consultant to the City of
Tacoma, discussed risk assessment at the landfill site. Black & Veatch.
acting as consultants to the city, provided graphical representation of
well locations and migration pathways. An agenda and fact sheet were
distributed.
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8) After the RI/FS was made public in February 1988, citizens had
concerns and unanswered questions.
Actions; On February 11. 1988. Ecology, In cooperation with EPA
and the City of Tacoma, conducted a public meeting to discuss
remedial alternatives for cleaning up leachate and methane gas at
the landfill. Questions relating to the RI/FS were answered and
public comments were recorded.
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3.0 SUMMARY OF MAJOR COMMENTS RECEIVED DURING THE PUBLIC
COMMENT PERIOD AND AGENCY RESPONSES TO THE COMMENTS
The public comment period was open from February 4 through March 4,
1988. Ecology held a public meeting In Tacoma on February 11, 1988 to explain
the study and the remedial alternatives. Formal comments "received at that
meeting concerned providing an alternate water supply, coordinating planning,
evaluating alternative design options, and Implementing new landfill
operations Including recycling and ash disposal. The last comment Is
considered beyond the scope of the FS.
\
Comments from members of the public, primarily Tacoma area residents,
regarding the FS report are summarized below. Questions were addressed to
U.S. EPA, Ecology, the Tacoma-Plerce County Health Department (TPCHO). and
City of Tacoma representatives and their consultants.
FORMAL COMMENTS
Four participants from the public presented formal comments during the
public hearing. Those comments are summarized below.
1) Provision of an alternative water supply for residents whose wells
have been contaminated regardless of the chosen alternative was a concern of
one participant.
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Response: The preferred alternative includes provision of an
alternate, unthreatened water supply (municipal water) to any resident
whose water supply is adversely impacted as further describes in the ROD
by contamination emanating from the landfill.
2) One comment addressed the need to incorporate long-term planning in
future studies. The speaker noted that seven years ago. many of today's
problems connected with the landfill were not known and not planned for.
Another comment addressed the need for more coordination in the planning
process between the consultants and agencies connected with landfill studies.
, \
Response; Long term planning of the landfill operation is conducted at
•"t"i<
the local level with assistance and review by the state. Selection of
the preferred alternative under CERCLA/SARA Included analysis of
long-term needs. Long-term planning Is part of the studies. Ecology a<
EPA agree that more coordination Is needed and have Incorporated this
Into ongoing community relation activities.
3) Several design options were offered by one participant who felt that
they should have been considered during the evaluation of remedial
alternatives. These options are as follows:
o An aeration facility to remove volatile material from the groundwater.
o A system of wells completely encircling the landfill to Intercept and
retrieve contaminated groundwater.
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o Incorporation of removable pumps and sequencing pumping to optimize
groundwater retrieval.
o Discharge of treated groundwater to the Simpson pulp mill or other use
of treated groundwater as a water supply.
o Use of extracted methane to produce electricity. '
Response; Ecology and EPA will take note of these suggestions and
they will be evaluated during the Remedial Design phase as
appropriate.
4) A comment was received concerning the potential threat to public
health caused by heat generation from spontaneous combustion of materials In
the proposed sealed landfill. Such conditions might lead to an explosion that
would endanger nearby apartments and their Inhabitants, and taxpayers would be
obligated to pay for the damage.
Response; The landfill will be continuously monitored so that
spontaneous combustion problems should not occur. Should a problem
occur, the landfill has a contingency plan and an emergency response plan
In plact.
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