United States Office of
Environmental Protection Emergency and
Agency Remedial Response
EPA/ROD/R10-92/042
September 1992
x°/EPA Superfund
Record of Decision:
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NOTICE
The appendices listed in the index that are not found in this document have been removed at the request of
the issuing agency. They contain material which supplement. but adds no further applicable information to
the content of the document. All supplemental material is, however, contained in the administrative record
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50272-1 01
REPORT DOCUMENTATION 11. REPORT NO. I 2. 3. Reciplenfs Accession No.
PAGE EPA/ROD/R10-92/042
4. Tide and Subdde 5. Report Date
SUPERFUND RECORD OF DECISION 09/30/92
pesticide Lab-Yakima, WA
First Remedial Action - Final 6.
7. Author(s) 8. Performing Organization Rept. No.
9. Performing Orgainlzation Name and Address 10. ProjecllT aakIWork Unit No.
11. Contracl(C) or Granl(G) No.
(C)
(G)
12. Sponsoring Organization Name and Address 13. Type 01 Report & Period Covered
U.S. Environmental Protection Agency
401 M Street, S.W. 800/000
washington, D.C. 20460 14.
15. Supplementary Noles
PB93-964608
16. Abstract (Uml!: 200 words)
The 10-acre Pesticide Lab-Yakima site is located at the Yakima Agricultural Research
Laboratory (YARL) in Yakima, Yakima County, Washington. The YARL occupies approximately
15 percent of the total site area, and the remainder is used for cultivation of row
crops and fruit trees. Land use in the area is predominantly residential, and several
residences south of the site obtain drinking water from private wells. The YARL, which
has operated since 1961, develops insect control technologies to benefit fruit and
vegetable agriculture in the Pacific Northwest. Wastes generated at the site consist of
a wide variety of pesticide mixtures; rinsates from the cleaning of sprayers and other
equipment; and solvents. The site contained a septic tank, disposal pipe, washdown pad,
and drainfield system used for the discharge of dilute pesticide compounds- In 1980,
YARL received interim status under RCRA; however, in 1983, unpermitted discharges led to
EPA investigations that revealed evidence of soil and potential ground water
contamination from leaching of contaminants through the highly permeable sand and
gravel. In 1988, YARL removed the drainfield, sampled soil and ground water, and
compiled monitoring information from four wells that had been installed that same year.
(See Attached Page)
17. Document Analysis a. Descriptors
Record of Decision - Pesticide Lab-Yakima, WA
First Remedial Action - Final
Contaminated Media: none
Key Contaminants: none
b. IdentilieralOpen.Ended Terms
.. "
c. COSA TI Reid/Group
18. Availability Stalamenl 19. Security Class (This Report) 21. No. 01 Pages
None 18
20. Security Class (This Page) 22. Price
Nn'n'"
- OI'"ONAL FORM 272 (4-77)
(See ANSI Z39.18)
See Instruclions on Reverse
(Formerly NTIS-35)
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EPA/ROD/R10-92/042
Pesticide Lab-Yakima, WA
First Remedial Action - Final
Abstract (Continued)
In 1990, three additional wells were added to further facilitate ground water assessment.
A RCRA Closure Plan, which was approved in 1990, provided for the removal and disposal of
the septic tank contents, excavation and removal of the tank itself, washdown pad
removal, additional background soil sampling, excavation and removal of contaminated soil
to obtain clean-up levels, conformational soil sampling around the removed structures,
installation of the three ground water monitoring wells, and 1 year of ground water
sampling. Because all waste residues, contaminated soil, and subsoil have been removed
or decontaminated pursuant to RCRA Clean Closure regulations, there are no contaminants
of concern affecting this site.
The selected remedial action for this site includes no further action with ground water
monitoring for 1 year. There are no costs associated with this no action remedy.
PERFORMANCE STANDARDS OR GOALS:
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UNITED
RECORD OF DECISION
DECLARATION, DECISION SUMMARY,
AND RESPONSIVENESS SUMMARY
FOR
YAKIMA PESTICIDE LABORATORY
YAKIMA, WASHINGTON
SEPTEMBER 1992
STATES ENVIRONMENTAL PROTECTION
REGION 10
1200 SIXTH AVENUE
SEATTLE, WASHINGTON.
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V.
VI.
TABLE OF CONTENTS
DECLARATION OF THE RECORD OF DECISION
DECISION SUMMARY
SECTION
I.
SITE NAME, LOCATION, AND DESCRIPTION. . . . . . .
II.
SITE REGULATORY HISTORY.
. . . . . .
. . . . . . . 1
III. CONTAMINANTS AND POTENTIAL EXPOSURE
PATHWAY OF CONCERN. . . . . . . . . . . .
. . . .
IV.
CHARACTERIZATION OF RISK.
. . . .
. . . .
. . . .
REMEDIAL ACTION SELECTED AND IMPLEMENTED
UNDER RCRA. . . . . . . . . . . . . . . ..
. . . .
SUMMARY OF POST-REMEDIAL SITE RISKS.
. . . . . .
VII. SELECTED REMEDY - NO FURTHER ACTION
DECISION. . . . . . . . . . . . . .
.......
IX.
VIII.SCOPE OF RESPONSE ACTION WITHIN SITE STRATEGY. . .
HIGHLIGHTS OF COMMUNITY PARTICIPATION. . . . . . . 8
X.
XI.
STATE ACCEPTANCE. . . .
..........
COMMUNITY ACCEPTANCE. .
. . . . .
........
~.
XII. DOCUMENTATION OF.SIGNIFICANT CHANGES. .
. . . . .
Appendices
Appendix. A:
Appendix B:
Details About CPFs and RfDs
Responsiveness Summary
Appendix C:
Administrative Record Index
PAGE
1
2
4
5
7
7
8
9
9
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DECLARATION STATEMENT
PESTICIDE LAB (YAKIMA) SITE
RECORD OF DECISION
DECLARATION FOR THE RECORD OF. DECISION
SITE NAME AND LOCATION
Pesticide Lab (Yakima)
Yakima, Yakima County, washington
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected remedial action
for the Pesticide Lab (Yakima) site in Yakima, Washington, which
was chosen in accordance with the requirements of the
Comprehensive Environmental Response, compensation, and Liability
Act of 1980 (CERCLA), as amended by the Superfund Amendments and
Reauthorization Act of 1986 (SARA) and, to the extent
practicable, the National oil and Hazardous Substances Pollution
contingency Plan (NCP). This decision document explains the
factual and legal basis for selecting the remedy for this Site.
The Washington State Department of Ecology (Ecology) concurs
with the selected remedy. The information supporting this
remedial action decision is contained in the administrative
record for this site.
SUMMARY OF RATIONALE FOR NOT TAKING ACTION
The u.S. Environmental Protection Agency (EPA) has
determined that the Pesticide Lab (Yakima) site does not require
further remedial action pursuant to CERCLA. This determination
is based on the assessment of present conditions at the site.
This.. site has been the subject of remedial activities pursuant to
RCRA. Remedial activities at the site according to RCRA
regulations and Ecology regulations have resulted in a "clean
closure" of the hazardous waste disposal system at the site.
"Clean closure" according to RCRA means that all waste residues,
. including subsoils, have been removed or decontaminated. For
this site contaminated material was defined as material
containing hazardous substances posing a risk of greater than 10-
6 based on a worst case residential exposure scenario. "Clean
closure" standards are sufficiently strict to protect the public
and the environment without requiring further care of the site
after remedial activities have been completed. It has been one
of the Agency's primary objectives in development of the RCRA
corrective action regulations to achieve substantial compliance
with the CERCLA remedial program. Monitoring of groundwater and
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remedial activities implemented under RCRA have resulted in
removal of contaminated material from the site (cleanup levels
have been achieved and, in most cases, contaminants were not
detected) allowing for unlimited use and unrestricted exposure
within the Site.
Considering the standards for achieving "clean closure" and
the determination that such standards have been achieved at the
Pesticide Lab (Yakima) site, it is evident that the conditions at
the Site do not warrant remedial action under CERCLA.
DECLARATION OF STATUTORY DETERMINATIONS
EPA has determined that it is not appropriate to use CERCLA
statutory authority to remediate this site. Part 265, Subpart G
of RCRA, as amended by the Solid Waste Disposal Act of 1980 is
the Federal authority under which this site was remediated. In
reviewing the present conditions at the site EPA has determined
that no action under CERCLA is necessary. A five-year review
will not be necessary for this site because no hazardous
substances remain on site above levels of concern.
CERTIFICATION OF COMPLETION
EPA has
necessary at
inclusion in
Construction
determined
this site.
the "sites
. Completion
that no further remedial action is
Therefore, the site now qualifies for
awaiting deletion" subcategory of th~
category of theN~tional Priorities List.
~~ministrator
Environmental Protection Agency, Region 10
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DECISION SUMMARY
PESTICIDE LAB (YAKIMA) SITE
SITE NAME, LOCATION, AND DESCRIPTION
The site listed on the NPL as the Pesticide Lab (Yakima)
Site is located at the Yakima Agricultural Research Laboratory
(YARL) in Yakima, Yakima County, Washington. The town is
situated in the southcentral section of Washington east of the
Cascade Mountains in relatively flat, dry land. Approximately
50,000 people are located in Yakima. The research laboratory
consists of numerous office and laboratory research buildings,
warehouses, storage sheds, maintenance buildings and
greenhouse/hothouse buildings occupying approximately 15% of an
approximately 10 acre parcel in Yakima. (Se~ Figure 1) The
remaining acreage is used for cultivation of row crops and fruit
trees. YARL is situated in a residential area within one-half
mile of three schools, two hospitals and three shopping centers.
The Site consists of a septic tank, disposal pipe, washdown pad
and drainfield system used for the disposal of dilute pesticide
compounds used at the YARL~
SITE REGULATORY HISTORY
The research laboratory, originally an orchard, has been in
operation since 1961. The primary activity at the laboratory
involves the development of insect control technologies that
benefit fruit and vegetable agriculture in the Pacific Northwest.
Records indicate that the area was sprayed with various pesticide
compounds including persistent organochlorine pesticides such as
DDT, Dieldrin, and Lindane. Workers at the laboratory used a
modified septic and drainfield system to discharge dilute waste
pesticide compounds. The system consisted of a 300 gallon.
concrete septic tank which drained a conventional toilet/sink and
an outside concrete surface washdown pad. Tank effluent was
discharged through a ~ile drain. Approximately 5,000 gallons of
rinsate from equipmen~ cleaning operations and less than 250
gallons of residual pesticide solutions were discharged into the
system annually for about 20 years (from 1965 to 1985). The unit
was the only hazardous waste management system at the YARL
facility. The unpermitted discharges resulted in investigations
under RCRA and CERCLA at the YARL facility. There were concerns
that pesticides and solvents had leached into the uppermost,
shallow, drinking-water aquifer were identified because of the
presence of highly permeable sands and gravels.
YARL submitted a RCRA Part A permit application in September
1980 and .received interim status. A preliminary assessment and
site investigation (PA/SI) was conducted in June 1982. Field
. work for the PAISI was limited to shallow soil sampling and a
failed attempt to drill to groundwater. The PAISI concluded that
soil w~s contaminated due to discharges from the septic system
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'.
"
JIIIUII"nIllUII: :
."..1'''''-' .".....
Ilgl~!wlmuuuc:
.-.-.--..........--....-
--.-.-.-.-.-
. ,
,'.otl
PESTICIDE
STORAGE
BUILDING
01' /~,..
':fI.:':':- +
+ .....
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l. #".U'U ='
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60
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. mOlars
20
~
Relerence: Y ARL (1987).
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incorrectly assumed groundwater depth of 20 feet. (Later the
correct depth was determined to be 35 feet). Based on the
results of the PA/SI, the site was proposed for the NPL in
December 1982 and finalized on September 8, 1983 (48 FR 40658).
The Site is currently on the NPL, based on the original 1982
Hazard Ranking Score of 29.33. The relatively low hazard ranking
of the site was based on sparse near-surface soils data and no
ground water monitoring data.
CONTAMINANTS AND POTENTIAL EXPOSURE PATHWAYS OF CONCERN
On June 2, 1988, a RCRA Facility Assessment (RFA) was
completed by EPA which included a preliminary characterization of
the conditions at the Site, identified additional work needed to
fully characterize the Site, and described the results from a
visual inspection. The RFA assessed exposure pathways that may
be of concern given the nature of the releases at the site and
the substances released. Preliminary on-site sampling identified
pesticides in septic tank water and the surrounding subsurface
soil. The report concluded that the extent of groundwater and
soil contamination could not be assessed without more
information. EPA and the Washington State Department of Ecology
(Ecology) coordinated investigative work and remedial oversight
at the site.
Wastes generated at the site consist of a wide variety of
pesticide mixtures, rinsates from the cleaning of sprayers and
other equipment, and solvents. The RFA estimated that
approximately 5,OQ-O gallons of rinsate from equipment cleaning
operations and less than 250 gallons of residual pesticide
solutions were discharged into the system annually for about 20
years (from- 1965 to 1985).. ~cology estimated that several
hundred compounds, in small quantities, were disposed of during
the 20 years that the septic tank/drainfield were in operation.
complete records indicating the names and quantities of chemicals
disposed of through the system are not available. Diluted
pesticides known to have been introduced into the system with
wastewater includ~~ut are not limited to Guthion, Sevin,
Malathion, Parathion, Tetraethylpyrophosphate (TEPP), DDT, Temik,
Methoxychlor, Kelthane, Lindane, Captan, Cyprez and Benelate.
- Heavy metals, including lead arsenate, and pesticide concentrates
were never discharged to the septic tank/drainfield system. An
example of the diversity and low volumes of of pesticides used
on-site is represented by Table 1, listing names and quantities
of pesticides used in the 1986 growing season. Even though Table
1 refers to pesticides used on-site in 1986 and the septic tank
system was closed in 1985, the Table represents the types and
quantities of pesticides used at the site in recent years.
DDTl. ~~ndane, Methoxychlor and Captan are organochlorine
pesticides. This class of compounds generally are persistent (in
soil for 30 plus years), exhibit low mobility in the soil and a
resistance to microbial and chemical degradation. Guthion,
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TABLEJ..
PESTICIDES FOR 1986 EXPERIMENTS AND PLOT MAINTENANCE
Advantage (I)a
Alar (Plant GR)b
Ammo (I)
Bayleton SOW (F)c
Bays; r 2SW (I)
Bay bue 1452 (I)
Baytex 4 (I)
Butamin P&O (I)
Bay FCR 1272 (I)
Captan 25 percent SP (F)
Casoron (H)-
ChI orban granules (I)
Cymbush (I)
Cyprex 6SW (F)
.Diaz;non (I)
Dibrom 8EC (I)
Dimil;n 25W (GR)
Di syston (I)
Dursban (I)
Furadan 15G (I)
Insectatapes (I)
HK-936 (I)
Monitor 4EC (I)
Horestan (I)
Nicotine sulphate
Nudri n (I)
1-2 gal
1 I b
1 I b
4 Ib
lIb
1 1 b
1 gal
1 cup (4 oz)
. 1 pt
11 1 b
20 Ib
lIb
1 qt
3 1 b
4 1 b
2 gal
10 1 b .
1 gal
3 1 b
-5 1 b
12 cartons
1 L
1 pt
2 1 b
2 pt
1 qt
Noxfire (I)
Omite CR (I)
Orthene (I)
Orthene (I)
PBU-26 PB-Nox (I)
PBU-26 piperonyl butoxide (I)
Parathion (1)
Pentac (I)
Pi rimor SOW (I)
Pounce (I)
Princep 4L (H)d
Pydr;n 2.4 EC (I)
Pyrenone (I)
Round-up (H)
SBP 1382 (I)
Sectro 1 (I)
Spur (I)
Supracide (I)
Supreme oil (I)
Surflan (H)
Tempo 2C
TH 6043 25W (GR)
TH 6044 25W (GR)
TH 6045 25W (GR)
Zo lone (I)
1 qt
3 1 b
1 Ib
1 lb
1 qt
1 pt
4 I b
1 1 b
1.5 lb
1 qt
1 gal
3 pt
1 cup (4 oz)
1.75 gal
1 pt
24 oz
1 qt
2 gal
50 gal
1 pt
16 oz
8 cz
8 oz
8 oz
1 gal
a (I) = Insecticide.
b (F) = Fungicide.
c (GR)= Granular insecticide.
d (H) = Herbicide.
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Malathion, Methoxychlor, Parathion and TEPP are examples of
organophosphate and carbamate pesticides which generally are not
persistent in soil (less than several months) and degrade
rapidly. Both organophosphates and carbamates are susceptible to
chemical and microbial decomposition.
The low mobility, low water solubility, and resistance to
degradation of organochlorine compounds suggest that they were
likely to be contained in the soil beneath the drainfield.
Organochlorine compounds have a strong tendency to attach to soil
organic and mineral colloids. In comparison, organophosphate and
carbamate compounds are dispersed rapidly from the soil due to
the.susceptipility of these compounds to chemical and microbial
decomposition. These compounds are not likely to be detected in
the soil. at the site.
Prior to remediation, the preliminary environmental pathways
of concern related to the hazardous waste disposal system were
groundwater, on-site soils and possibly surface water.
Additionally, if contamination of ground/surface water wad
detected, other pathways of concern could be bioaccumulation of
contaminants in fish and human exposure resulting from ingestion
of and direct contact with ground/surface water and soil and
possible. ingestion of bioaccumulated contamination in the food
chain.
Air was not a pathway of concern for contaminant migration
because contaminants were introduced to the soil 2 feet below the
ground surface and were not likely to migrate to the air because
of their low volatility. The potential for contaminant migration
through the. air is extremely low.
Subsurface gas was not a pathway of concern for contaminant
migration because the contaminants were introduced in dilute form
and not capable of developing subsurface gas in explosive or
toxic concentrations. .
In 1983, Ecology collected a water sample from the septic
tank~ The sample was analyzed by the u.s. EPA Region 10
laboratory. Concentrations of Aldrin, Dieldrin, DDT, Endosulfan,
and Endrin found in the septic tank sample exceeded water quality
criteria for drinking water consumption.
Prior to remediation, surface water was. identified as a
potential pathway for human exposure to contaminants associated
with the septic tank drainfield. Wide Hallow Creek is located
approximately 0.5 mile south of the site in the presumed
direction of groundwater flow. Because Wide Hallow Creek is used
for bank fishing and domestic irrigation, if groundwater were
contaminanted, and if it discharged to this creek, it could
affect aquatic biota, irrigated crops, and people who use these
resources. Wide Hallow Creek is the nearest surface water
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downgradient from the site in the presumed direction of
groundwater flow. contaminated groundwater flowing toward the
south-southeast may release contaminants to Wide Hallow Creek.
Wide Hallow Creek flows east-southeast to eventually join the
Yakima River. Surface runoff is minimal because the soils are
permeable and the gradient is relatively gentle (3 percent). .
Water to Yakima residents is either pumped from the Naches River
or from municipal wells which are not within the vicinity of the
site (closest backup well is one and a half miles from the site).
The Naches River is 2.5 miles north of the site.
Another pathway of concern for contaminant migration, prior
to remediation, was groundwater. Several residences south of the
site obtain drinking water from domestic wells. Because the
septic tank and drainfield system allowed pesticides to permeate
the soil and the area is characterized by highly permeable sands
and gravels, there was a concern that pesticides may have leached
into the shallow drinking water aquifer. Some of these domestic
wells were presumed to be downgradient of the site.
Soil was identified as another plausible pathway of concern
for this Site. In 1983, Ecology collected three subsurface soil
samples (at depths of 2 feet, 5 feet, and 5.5 feet) from the
drainfield area. Samples were analyzed by the u.S. EPA Region 10
lab. Analytical results indicated that the concentration of DDT
was 3 mg/kg in one soil sample collected near the drainfield.
CHARACTERIZATION OF RISK
In 1988, YARL removed the drainfield, sampled soil within
and outside the excavated drainfield area, sampled and gathered
additional groundwater monitoring and sampling information from
four monitoring wells (installed in April of 1988) and performed
in-situ aquifer testing (slug tests). Sampling was conducted for
a lengthy list of primary and indicator parameters developed to
determine ground water quality and to monitor for the presence of
the compounds believed to have been discharged through the septic
tank/drainfield system. .
~.'The subsequent study that was developed concluded that the
ground water quality was generally excellent and that the
likelihood for ground water contamination, as a result of the
hazardous waste disposal activities, was low at the site. The
study detected a variety of hazardous pesticides and carrier
solvents in the tank sludge and drainfield. Based on these data,
EPA decided that the Site was subject to the requirements for
hazardous waste treatment, storage, and disposal (TSD)
facilities, under RCRA.
Additional groundwater monitoring wells were installed in
1990, forHa'.total of seven on-site wells, to facilitate
groundwater assessment. Quarterly monitoring (five quarters)
indicate groundwater concentrations of DDT and Dieldrin and other
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regulated pesticides did not exceed health-based criteria or
cleanup levels. No organic compounds were detected.
Based on the results of the groundwater monitoring, EPA and
Ecology believe that the groundwater associated with this site
does not pose a significant risk to public health and the
environment. Similarly, EPA and Ecology are not concerned about
surface water contamination via groundwater contamination.
REMEDIAL ACTION SELECTED AND IMPLEMENTED UNDER RCRA
Based on the low hazard ranking and the initial ground water
data, clean closure pursuant to RCRA requirements for interim
status facilities (40 CFR Part 265) was undertaken instead of
initiating either a Subpart B application under RCRA or
conducting a Remedial Investigation and Feasibility Study
pursuant to CERCLA. This approach is consistent with Ecology's
Model Toxics Control Act Cleanup Regulations.
An initial Closure Plan ("clean up plan") for the septic
tank and drainfield, including a monitoring plan for sampling and
analyzing groundwater and soil, was submitted by YARL in January
1985. A final revised Closure Plan was submitted on September
12, 1989 for approval after four groundwater monitoring wells
were installed in April 1988 at the Site. The September 12, 1989
final draft Closure Plan was released for public comment in
December 1989. No comments were received. The Closure Plan was
approved on January 30, 1990. As required by the approved
Closure Plan, three additional wells were drilled and completed
by July 1990.'
The principal elements of the Closure Plan focused on
removing the potential sources of contamination through removal
and disposal of the septic tank contents, excavation and removal
of the septic tank itself, washdown pad removal, additional
background soil sampling, excavation and removal of contaminated
soil to obtain cleanup levels, confirmational soil sampling
around the removed structures, installation of ground water
monitoring wells and one year of groundwater sampling.
Calculation of cleanup levels for contaminants at this site were
based on EPA's proposed RCRA Subpart S standards as described in
55 FR 30798, July 27, 1990. Where cleanup levels for specific
contaminants were not identified, consistent with Subpart S, the
Agency approved cleanup levels based on a cumulative
noncarcinogenic risk estimate of less than 1.0 assuming daily
intake and a lifetime incremental cancer risk of less than one in
a million (within EPA's and Ecology's acceptable risk range for
carcinogens). levels.
Cleanup levels were developed, as described above, for those
pesticide compounds found in high concentrations in the septic
tank that were moderately to highly mobile, persistent or toxic.
The cleanup levels adopted in the Closure Plan are as follows:
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Pesticide compound
concentration (ppm)
2,4 D
chlorpyrifos
DDT
Dieldrin
Disulfoton
Endosulfan ( and II)
Endrin
Heptachlor
Heptachlor Epoxide
Hexachlorocyclohexane
Lindane
850.000
255.000
0.830
0.440
3.000
4.000
20.000
0.200
0.080
0.500
25.500
Reference Doses (RfDs) and carcinogenic Potency Factors
(CPFs) were obtained from EPA's Reference Dose Trackinq System,
August 1989, and EPA's Inteqrated Risk Information System (IRIS).
The primary exposure route of concern, in the absence of '
groundwater contamination, was through soil. Cleanup levels were
established assuming the most conservative exposure scenario
because the site is surrounded by residential areas. The
scenario assumed oral ingestion of contaminated soil by children.
See Appendix A for more details about RfDs and CPFs.
"Clean closure" activities occurred in four phases. Phase
One consisted of removing and disposing of the septic tank
contents, the sep~~p tank and the washdown pad followed by
sampling of tank contents and soil. In Phase Two, soil was
excavated from around the septic tank and washdown pad, followed
by sampling'. Phasei'Three consisted of soil excavation from
around the washdown pad area, followed by soil sampling. The
last and final phase, Phase Four, included pipe removal and soil
sampling in the area around the pipe. Soil was successively
excavated in phases until confirmational sampling indicated that
"clean closure' had been achieved.
~':\"'"
In total, apprqximately 40 cubic yards of contaminated soil
conta'ining pesticides above the cleanup levels were removed from
the former tank/pad area and disposed of at a permitted hazardous
waste TSD facility.
Two background samples taken during the initial closure
phase (tank/pad removal) showed low parts-per-billion (ppb)
levels of pesticide residuals such as Dieldrin and DDT. These
and similar substances are expected to be found in this area due
to historical, legal application of pesticides totally unrelated
to the former YARL septic disposal practices.
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SUMMARY OF POST-REMEDIAL SITE RISKS
PCBs, volatile organics, semi-volatile organics and metals
were below detection limits in confirmational analysis of soil
samples. Organophosphorus pesticides, identified in the tank
contents, also were not detected in the soils around the septic
tank system. Final confirmational soil monitoring indicated that
average DDT and Dieldrin concentrations were below cleanup
levels, Endrin and Endosulfan were several orders of magnitude
(100 to 1000 times) below cleanup levels and other organochlorine
pesticides were not detected.
Analytical data based on quarterly monitoring (45 valid
samples in 5 quarters) indicate groundwater concentrations of
DDT, Dieldrin and other regulated pesticides and volatile
organics were below cleanup levels and in fact were not within
the detectable range. (Detection limits are several orders of
magnitude below cleanup levels.) Minor quantities of metals,
including mercury, vanadium, and zinc, were detected lower than
the maximum contaminant levels (MCLs) for drinking water.
Based on the removal of contaminated equipment and
excavation of contaminated soil, and confirmational soil and
groundwater monitoring data, EPA and Ecology agree that hazardous
materials were removed from the site thus allowing for unlimited
use and unrestricted exposure within the Site. Confirmational
monitoring of soil and groundwater demonstrate that no
significant risk to pUblic health or the environment is posed by
the residual materials remaining at the site. All exposure
pathways of concern have been addressed.
No environmental risk.has been identified for this
For example, no. critical habitats or endangered species
habitats of endangered species have been identified for
site.
site.
or
this
SELECTED REMEDY - NO FURTHER ACTION DECISION
EPA and Ecology agree that the site is protective of public
health and the environment for all pathways of exposure and no
further action is necessary in order to provide protection of
human health and the environment.
The sampling and analysis section of the Closure Plan was
reviewed and approved by the EPA and Ecology. The plan was
suitable to characterize the potential contamination of the Site
and to determine contaminant removal from the site. Appropriate
quality control measures and laboratory quality control protocols
were implemented for the sample collection and analysis
activities in accordance with the approved Closure Plan. Sample
analyses were conducted according to methods contained in the EPA
document "Test Methods for Evaluating, Solid Wastes,
Physical/Chemical Methods (SW-S46)."
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EPA's and Ecology's proposal for No Further Action is based
on the results of the post-removal soil and groundwater sampling
which indicate that the risk posed by substances at the site is
within the protective range. Specifically, substances detected
in soil and groundwater sampling are below or within the 10-6
risk range. Most substances analyzed for in soil and groundwater
were not detectable.
The Closure Plan, which specifies RCRA closure standards for
a particular site, detailed the requirements for "clean closure"
for the Yakima site. Both EPA and Ecology RCRA programs have
certified clean closure completion. Clean closure as defined in
the RCRA Closure Plan and implemented at the site is defined as
the cleanup to a level of soil concentrations less than the
established risk-based cleanup levels. Given the "clean closure"
(no significant contamination left at the site) and the unlimited
use and unrestricted exposure classification for the site,
operation and maintenance activities and a 5-year review are not
required at the site.
SCOPE OF RESPONSE ACTION WITHIN SITE STRATEGY .
. The Site as defined on the NPL consists of a septic tank,
drainfield and washdown pad. Removal of the septic tank and
washdownpad and the excavation of the drainfield and surrounding
contaminated soil constitute the complete and final action
specified for the Site under Federal and State Superfund and RCRA
programs. .
HIGHLIGHTS OF COMMUNITY PARTICIPATIQN
Community. involvement activities for this site are unusual
because, although listed on the NPL, the site has not been
managed under the authority of CERCLA. Remedial actions at the
Site were conducted pursuant to RCRA clean closure requirements.
As a RCRA site, community relations activities prior to closure
have been conducted pursuant to RCRA requirements.
During the remedial activities conducted under RCRA,
community concern and involvement regarding the site was minimal.
Thi~ ..is particularly reflected by the fact that no public
comments were received during the public comment period for the
1989 final draft Closure Plan.
Concurrent with approval of the ROD, EPA is proposing to
delete the Site from the NPL. A Community Involvement Plan for
Site Deletion was prepared in the Summer of 1992. This plan
outlines the necessary public involvement requirements to delete
the site from the NPL under CERCLA. The Agency compiled a
mailing list of key local officials and other interested parties,
established information repositories, held a public hearing, and
notified the local media about the Proposed Plan and public
comment period. The public hearing was held on September 10,
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1992. The 30-day public comment period for the No Action
Proposed Plan ended on September 22, 1992. No comments were
received from the public during either the comment period of the
public hearing.
The information repositories and deletion docket are located
at:
Washington Department of
Central Regional Office
Attn: Michelle Slater
106 South 6th Avenue
Yakima, WA 98902
Ecology
and
Region 10 U.S. EPA Library
1200 6th Avenue
-Seattle, WA 98101
Community activities surrounding the deletion of the Site
from the NPL will comply with the NCP and "Community Relations in
Superfund: A Handbook", as appropriate.
STATE ACCEPTANCE
The State of Washington's Department of Ecology has
concurred on this remedy without comment.
COMMUNITY ACCEPTANCE
EPA did not receive any public comments on the Closure Plan
for this site. The Closure Plan proposed remedial action for
this site included cleanup levels. A 30-day comment period was
provided.
A 30-day public comment period was also provided for the
RCRA equivalency determination and CERCLA's No Further Action
Proposed Plan. No public comments were received.
DOCUMENTATION OF SIGNIFICANT CaANGES
There have been no significant changes in the decision as
described in the Closure Plan.
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Appendix A
Details About CPFs and RfDs
CPFs have been developed by EPA's Carcinogenic Assessment
Group for estimating excess lifetime cancer risks associated with
exposure to potentially carcinogenic chemicals. CPFs, which are
expressed in units of (mg/kg-day)-l, are multiplied by the
estimated intake of a potential carcinogen, in mg/kg-day, to
provide an upper-bound estimate of the excess lifetime cancer
risk associated with exposure at that intake level. The term
"upper bound" reflects the conservative estimate of the risks
calculated from the CPF. Use of this approach makes
underestimation of the actual cancer risk highly unlikely. CPF
are derived from the results of human epidemiological studies or
chronic animal bioassays to which animal-to-human extrapolation
and uncertainty factors have been applied.
RfDs have been developed by EPA .for indicating the potential
for adverse health effects from exposure to chemicals exhibiting
noncarcinogenic effects. RfDs, which are expressed in units of
mg/kg-day, are estimates of lifetime daily exposure levels for
humans, including sensitive individuals, that is not likely to be
without an appreciable risk of adverse health effects. Estimated
intakes of chemicals from environmental media (e.g., the amount
of a chemical ingested from contaminated drinking water) can be
compared to the RfD. RfDs are derived from human epidemiological
studies or animal studies to which uncertainty factors have been
applied (e.g., to account for the use of animal data to predict
effects on humans). These uncertainty factors help ensure that
the RfDs will not underestimate the potential for adverse
noncarcinogenic effects to occur.
Excess lifetime cancer risks are determined by multiplying'
the intake level with the cancer potency factor. These risks are
probabilities that are generally expressed in scientific notation
(e.g., lx10-s or 1E-6). An excess lifetime cancer risk of 1x10-s
indicates that, as a plausible upper bound, an individual has a
one-in one million chance of developing cancer as a result of
site-related exposure to a carcinogen over a 70-year lifetime
under the specific exposure conditions at a site.
Potential concern for noncarcinogenic effects of a single
contaminant in a single medium is expressed as the hazard
quotient (HQ) (or the ratio of the estimated intake derived from
the contaminant concentration in a given medium to the
contaminant's reference dose). By adding the HQs for all
contaminants within a medium or across all media to which a given
population.may reasonably be exposed, the Hazard Index (HI) can
be generated. The HI provides a useful reference point for
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gauging the potential significance of multiple contaminant
exposures within a single medium or across media.
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