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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

 
  • 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.
 
  • 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.
 
  • 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.
 
  • 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.
 
  • 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.

Section 5 Baseline Risk Assessment

 
  • Costs assume that only a human health risk assessment will be necessary.  Costs include site review and visit by assessor, evaluation of chemicals and exposure pathways, calculation of intake variables and toxicity variables, validation of calculations, and assessment report preparation.
 
  • Costs assume that all analytical data from the remedial investigation meet Level 3 criteria and have been fully validated.

Section 6 Corrective Measure Study (CMS)

 
  • It is not known at this time if a CMS will be necessary to close the site.  However, to meet the EPA cost request, it is assumed that a CMS will be performed based on the results of the remedial investigation and the baseline RA.
 
  • CMS cost estimate assumptions include analysis of closure criteria with updated information from the investigation and risk assessment, identification of applicable technologies and screening, and formulation of corrective action alternatives and their evaluation.
 
  • Costs include an initial draft to CSSA, a final draft to regulatory agencies, and a final CMS.

Section 7 Closure Implementation

 
  • 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.
 
  • 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.
 
  • 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.

Section 8 Closure Report

 
  • As-builts, a certification file review, and report preparation will be performed prior to certification by a state-registered P.E. Costs for certification and preparation of a draft deed recordation are also estimated.

The associated schedule of closure actions in Table 9.2 presents an estimate of working days that may be necessary to complete all assumed closure actions for B-20.  At this time, it appears that the 180-day schedule for closure can not be met and that an extension of time will be requested.