2.1.2 Response Actions to Date
October 19 through 24
During this week, ERRS began to receive sand and gravel
(2-1/2 inch minus), which will be used to backfill the excavation. The material
was stockpiled in the test track area on the other side of the new highway from
the excavation area, and START collected samples for laboratory testing.
Now that treated water from the water treatment system is
being discharged directly to the wetland area, the additional storage tanks for
the treated water (which had been used to store the water pending laboratory
results) were emptied and then demobilized from the site. At the end of this
reporting period, approximately 600,000 gallons of water had been recovered
from the excavation, treated, and discharged.
ERRS continued to excavate and set shoring boxes. By the end
of the week, the shoring boxes for Bays 1 through 5 had been connected in a continuous
row aligned approximately north-south. Surveyors were called out to the site to
locate and stake the locations of boreholes BH05, BH03, B3, F8, and F9. The
shoring for Bay 5 was set up as a half-length bay to allow for the extension of
the north-south excavation axis to extend far enough to support the shoring for
the planned east-west excavation, which will target an area of heavy
contamination identified by the Geoprobe boreholes installed and sampled in
Excavated soil is stored in a series of seven containment
cells that each hold approximately 250 cubic yards. Per the landfill's
criteria, a sample from the soil in each cell is collected and analyzed for
parameters of concern (initially VOCs, PCBs, SVOCs, and RCRA metals), and the soil
is not moved to the main contaminated soil stockpile until laboratory results
indicate that the soil is non-hazardous. During this reporting period, the
landfill indicated that the SVOCs and RCRA metals could be discontinued, and
only VOC and PCB analyses continued for the waste disposal profiling.
October 26 through 31
Each morning, the excavation was full of groundwater
and/or precipitation that had accumulated overnight, so two ERRS workers
came in early each day to start operating the groundwater pump and water
treatment system so that excavation can begin after the rest of the crew
arrived. By the end of this week, approximately 900,000 gallons of water had
been treated and discharged.
During this reporting period, ERRS began to load the non-hazardous
contaminated soil into trucks with trailers for transfer to the Subtitle D
landfill in Hillsboro, Oregon. By the end of the week, a total of
approximately 1,700 tons had been hauled off site for disposal.
Results for a sample of contaminated soil from one of the
containment cells indicated that the concentration of tetrachloroethylene (PCE)
was high enough that the sample could not be assumed to be non-hazardous
without a TCLP test. Because the TCLP testing would take too long, EPA assumed
that the soil in that cell was hazardous, and the soil was placed in a separate
hazardous waste stockpile.
Shoring for Bay 6 was located and placed directly adjacent
to the east of Bays 4 and 5. The northern end of Bay 6 was placed in alignment
with the northern end of Bay 5. Because Bay 5 was a half-length bay, the
southern end of Bay 6 is located at about the mid-length point of Bay 4. During
excavation, dense non-aqueous phase liquid (DNAPL) was observed in the bottom
of Bay 6. At the end of week, excavation was mostly completed in Bay 6 and the
shoring was set up in Bay 7.
ERRS received the Daramend soil amendment at the site.
Daramend is an anaerobic bioremediation agent which will be mixed with the
backfill to promote degradation of any residual PCE or trichloroethylene (TCE).
Laboratory results from samples of the overburden were
received and indicated that the soil contained PCBs at concentrations less than
50 milligrams per kilogram (mg/kg), along with polycyclic aromatic hydrocarbons
(PAHs). Based on these results, EPA decided not to use the soil as backfill,
and instead to dispose of it as non-hazardous contaminated soil.
On Saturday, October 31, a significant rain storm occurred
at the site, so site work was limited to operating the groundwater pump and
water treatment system.
November 2 through 7
During this reporting period, groundwater pumping,
treatment, and discharge continued. At the end of the reporting period,
approximately 1.4 million gallons of water had been discharged.
ERRS encountered a problem where infiltrating groundwater in
Bay 1 continued to carry sand from behind the shoring plate (i.e., the sand
from the previous removal action backfill) into the excavation, which
threatened to undermine the ground surface outside the shored excavation and
which tended to clog the pump. To prevent the sand infiltration, ERRS added the
2-1/2 inch minus backfill to the bottom of Bay 1 to raise the bottom of the
excavation up above the bottom of the shoring plates.
ERRS continued to excavate in Bays 6 and 7, and ERRS began
to install the shoring and excavate the overburden in Bay 8. ERRS continued to
place excavated contaminated soil into the containment cells, and START
continued to collect soil samples for rush laboratory analyses. Once laboratory
results were obtained indicating non-hazardous, ERRS moved soil from each
containment cell to the non-hazardous stockpile. The excavated contaminated
soil from Bays 6 through 8 was wet and sludgy, so ERRS mixed the contaminated
overburden soil to the soil in the containment cells to reduce the moisture
ERRS continued to load trucks and trailers with contaminated
soil for the landfill. By the end of this week, a total of approximately 4,000
tons had been sent off site for disposal.
November 9 through 14
On Monday, November 9, EPA performed a safety audit of the
ERRS continued to operate the water treatment system. At the
end of this reporting period, approximately 1.9 million gallons of water had
been pumped, treated, and discharged.
During this reporting period, ERRS finished excavating in
Bays 6-8 and began to backfill. Backfill consisted of sand mixed with the
Daramend amendment up until over the level of the groundwater table. ERRS also
continued to receive sand to be used as backfill. At the end of this week,
backfill also began in Bays 1 through 5.
ERRS continued to load trucks with contaminated soil for
off-site disposal. By November 11, approximately a total of almost 6,200 tons
of non-hazardous soil had been transported to the Subtitle D landfill in
Hillsboro, Oregon. Beginning on November 12, ERRS began to send the non-hazardous
soil to the Subtitle D landfill in McMinnville, Oregon, instead. By the end of
the week, approximately 700 tons of contaminated soil had been sent to
McMinnville, for a total of approximately 6,900 tons of non-hazardous soil
disposed of off site.
Also beginning on November 12, hazardous soil was loaded for
transport to the Subtitle C landfill in Arlington, Oregon. By the end of the
week, approximately 330 tons of hazardous soil was sent off site for
Barry Sanford from the Oregon Water Resources Department
(WRD) visited the site to confer with EPA on how best to decommission the
groundwater circulation wells (GCWs). Additionally, four monitoring wells,
including two continuous multichannel technology (CMT) wells (CMT-2 and CMT-3),
were located in the area of the new gravel laydown yard. The ground surface
around these wells was raised, and WRD conferred with EPA on how to address
Laboratory results for contaminated soil in one containment
cell indicated PCE concentrations above the TCLP threshold. Rather than
submitting a sample for TCLP testing, EPA assumed that this soil was hazardous
and transferred it to the hazardous waste stockpile.
November 16 through 21
During this reporting period, ERRS continued to operate the
water treatment system. At the end of this reporting period, a total of
approximately 2.2 million gallons of water had been pumped, treated, and
ERRS also continued to load trucks and trailers with
contaminated soil for disposal at the off-site landfills. By the end of this
week, a total of approximately 9,600 tons of non-hazardous soil and 770 tons of
hazardous soil had been transported off site for disposal.
Backfill continued in Bays 6-8 and Bays 1 through 5. A
compaction testing subcontractor was on site twice this week to perform in situ
compaction testing of the backfilled sand and gravel.
During backfill, ERRS removed the shoring materials as
bottom level of the excavation rose. Before removing shoring plates, spreader
bars, and posts, ERRS decontaminated them with water processed through the
treatment system using a water truck. The wash water was drained back into the
excavation to aid in the compaction of backfill.
2.1.3 Enforcement Activities, Identity of Potentially Responsible Parties (PRPs)
2.1.4 Progress Metrics