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i <br /> SECTION 8 BLANK <br /> SECTION 9 BLANK <br /> i SECTION 10 CONSTRUCTION DETAILS <br /> E <br /> Section 10.1 Order of Work <br /> All permits and approvals as may be required for this project shall be secured or <br /> ordered immediately after award of the contract or'their acquisition timing determined <br /> 1I such that the same is not a cause for delay. All items required for this project which <br /> may have long lead times shall' be ordered immediately after award of the contract to <br /> E assure that their acquisition is not the cause for any delays. <br /> Section 10.2 Inspections <br /> All work under this contract shall be under the control and inspection of the Engineer. A <br /> schedule of inspection shall be determined at the preconstruction meeting. The <br /> Contractor shall notify the Engineer of any changes in the work schedule. <br /> Section 10.3 Vapor Extraction System <br /> The proposed VES shall utilize existing vapor extraction wells VW-1, VW-3, and VW-5s, <br /> three new shallow vapor wells, avacuum blower, and vapor phase carbon to address the <br /> i' hydrocarbon impacted soil. Three new shallow vapor wells are proposed to effectively <br /> remediate impacted soil and to capture off-gas from air sparging. The new vapor wells <br /> shall be constructed of 2-inch schedule 40 PVC and shall be screened from approximately <br /> 15 to 30 feet below ground surface (bgs). <br /> The VES shall be operated with lair flow rates of approximately 35 cubic feet per minute <br /> (cfm) per well and approximately 20 inches of mercury per well to achieve a radius of <br /> influence for each well of approximately 30 feet. A map showing the estimated radius of <br /> influence is included in the plans. The VES shall be operated using individual wells or sets <br /> of vapor wells in sequence, rather than operating all wells concurrently. This approach <br /> shall minimize the size and inherent operating costs of the vapor extraction equipment, <br /> while still allowing maximization of airflow from individual wells. <br /> Based on the removal rates of petroleum hydrocarbons observed during the vapor <br /> extraction pilot tests (about one pound per day per one well), vapor phase granular <br /> activated carbon was selected as the method of off-gas abatement. The removal rate is <br /> expected to increase with the addition of the air sparging component. Removal rates are <br /> expected be the greatest during the first several months of operating the system and are <br /> expected to exceed the allowable emission limit without off-gas treatment. The use of <br /> vapor phase granular activated carbon is a proven technology, resulting in minimal down <br /> time of the system. When extraction rates decrease to less than two pounds per day, <br /> elimination of the off-gas treatment shall be proposed to PHS/EHD and SJVUAPCD. <br /> Subsurface piping shall direct eXtracted vapor from .the wells to a nearby remediation <br /> enclosure. Components of the VES located in the remediation enclosure shall include the <br /> following: a vapor extraction bjower that extracts vapor from the wells through the <br /> subgrade piping; a flow indicator that measures extracted airflow; a condensate separator <br /> to remove entrained droplets of moisture; two canisters connected in series containing <br /> vapor-phase granular activated carbon; associated piping, control valves, pressure <br /> SP7 <br /> jl <br />