ARCHIVED REPORTS_2011 REVISED FEASABILITY STUDY

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amec— discrete sampling depths). The estimated cost for this investigation is approximately $1.2 million. • Pre-construction costs include engineering design and legal/permitting costs, which are assumed to be 6% and 5% of capital costs, respectively, for a total cost of approximately $3.2 million. • The well spacing for the recirculation wells is based on design analysis presented in Hyndman et al. (2000) and is assumed to be on 3-feet centers. Hyndman and collaborators used contaminant transport modeling coupled to a cost optimization algorithm to determine optimal well spacing. Closer well spacing allowed for more effective distribution of substrate and microbes, more efficient pumping, and lower O&M costs. The higher cost of more closely spaced recirculation wells was offset by lower O&M costs. The total cost for installation of the recirculation wells is estimated at approximately $13.3 million. • Delivery system costs include costs for the down-well pumps (one pump per well) and the injection modules. Each injection module is assumed to control ten (10) recirculation well pairs (20 wells total). As described above, the injection modules would consist of a small buildings/shed that would house supervisory control and data acquisition (SCADA), mixing tanks, pump controllers, flow instrumentation, and associated piping. Dividing the total number of wells (1,500) by 20 yields 75 injection modules. The cost for each injection module is estimated at $125,000 for a total of$9.4 million. The cost for each down-well pump is estimated at $3,500 for a total of$4.5 million. The total estimated cost for the delivery system which includes the injection modules, the down-well pumps, and trenching/piping is estimated to be approximately $14.5 million. • Installation of a performance monitoring transect of 7-channel CMT wells downgradient of the bio-curtain on 100 feet centers (same depth and spacing as remedial design CMT well transect) is estimated at approximately $875,000. • Supervision/Labor costs include construction management, well development, and groundwater sampling. Construction management costs are estimated at 6% of capital costs. Well development and sampling are very minor components of this task. The total cost for supervision and labor is estimated to be $1.8 million. • O&M costs include electricity costs, maintenance, and quarterly performance monitoring (approximately $303,000 per year). Total annual O&M costs are estimated to be $1.0 million per year, and the NPV for 30 years (7% discount rate) is estimated to be $12.5 million. AMEC Geomatrix, Inc. \\oad-fs1\doc_safe\9000s\9837.006\4000 REGULATORYTFS Assessment_Apx B_01 2711\Attachment B.2\Attach B-2.doc 132-10