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[Closure
Plan]
Partial Facility Closure Plan for
B-20 Detonation Area
March 1994
Section 9
Closure Costs and Schedule
In
the January 13, 1994, EPA letter to CSSA, costs and a revised schedule for the
closure of the B-20 are requested. An estimate of costs to close B-20
under stated assumptions are presented in this section in such a manner that the
costs correspond to sections 4 through 8, the five steps for closure under 31
TAC 335 Subchapter S, risk reduction standard 3. The revised schedule is
also based on assumptions of estimated time to complete the proposed or assumed
closure actions discussed in sections 4 through 8.
To
estimate costs associated with closure of the B-20 site, proposed closure
actions were based on results of preliminary sampling and analysis or a
conservative estimate of a possible closure action. For example, proposed
field actions included in the remedial investigation (section 4) were based on
preliminary results and a statistical methodology for obtaining standard data
quality objectives of closure investigations and baseline risk
assessments. The proposed B-20 closure schedule for the remedial
investigation was based on an estimate of time to complete each action and
taking into account working days while considering weekends, probable holidays,
and possible downtime or other field equipment problems that are typically
encountered and resolved during investigations.
Costs
estimated for closure of B-20 are presented in Table 9.1, and the
associated schedule is in Table 9.2. Assumptions for these costs
are as follows:
Section
4 Remedial Investigation
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- Prescreening
for UXO does not include subcontractor costs, as it is assumed that CSSA and
RRAD will work with Army personnel to set up a team of UXO
professionals. Prescreening costs include labor for setting up the
field project, labor costs for a CSSA contractor observer, and material
costs for health and safety equipment.
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- Magnetometer
survey costs include equipment rental, a subcontractor UXO-qualified field
team, health and safety equipment, and assumes that the prescreening has
resulted in safe traverse to each crater. The survey is costed for 100
traverses, each 50 feet in length, for the sixteen craters. Data
evaluation is also included.
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- Subsurface
drilling costs assume that safe traverses for equipment and personnel have
been established to each drilling location. It is assumed that each
area will be cleared of UXO prior to drilling and that no special health and
safety precautions (such as remote drilling) will be necessary. Costs
include a CSSA contractor field team, local drilling subcontractor, hollow
stem auger and air coring capabilities on the rig, retrieval of soil/rock
samples, and grouting of each borehole. All decontamination rinsewater
and soil/rock cores will be left at each borehole. Analytical costs
are for the number of subsurface soil samples and associated QA/QC samples
per analytical parameter shown in Table 4.5. Analytical costs are for
Level 3 DQO and assume a standard turnaround time.
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- Verification
sampling costs assume that safe traverses without UXO have been established
for each sampling location. A contractor field team will collect
surface soil, surface water, and sediment samples. Analytical costs
are based on the number of samples and associated QA/QC samples per
analytical parameter as shown in Table 4.5
and Table 4.6. Analytical costs
are for Level 3 DQO and assume a standard turnaround time.
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- Estimates
for the investigation report cost include Level 3 data validation
(approximately 2 hours per sample), data evaluation (tables and figures),
field investigation techniques and deviations from the closure plan, field
results, analytical results, and conclusions and recommendations for the
next step of closure as discussed in this document.
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- The
remedial action selected for cost estimation purposes is discussed in section
7. For the purpose of preparing funding estimates, it is
assumed that a conservative (worst case) closure action - a RCRA
landfill-type camp - will be necessary to fulfill applicable regulations for
closure. These costs are estimated based on the work required to
design, construct, and maintain a RCRA landfill-type cap. A landfill
cap represents the most extensive closure option which may be required at
the site. Other closure options, which may be less costly, will be
more fully assessed after the results of the remedial investigation are
available.
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- The
RCRA landfill cap is costed assuming the 27.5-acre site will be graded and
tilled (and that all UXO have been identified and destroyed or
removed). A clay liner 2 feet in thickness will be constructed and
overlain by a 60-millimeter-thick HDPE liner, geonet, geotextile, and a top
1-foot-thick soil cover with vegetation and drainage structures.
O&M costs are included.
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- Institutional
control costs are estimated, including warning signs, a fence with locked
gate, and deed recordation. Costs for the survey plat requested in the
January 13, 1994, EPA letter to CSSA are included.
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