FIELD DOCUMENTS FILE 2 - Laserfiche WebLink

Home Browse Search

George's Service Remedial Action Work Plan Project No.425.2 June 30,2011 As expected, the vacuum drawdown response was indicative of good hydraulic conductivity in the northern portion of the site(VEW-2, MW-2 and MW-5). No response was observed in well in the eastern and southern portions of the site (MW-1, MW-2x, MW-3, MW-4 and MW-8). Analytical data and system operational parameters were evaluated to estimate the mass removed during the pilot test study. Based on an estimate of average flow rate of 105 cfm, a total of 14.3 pounds or 2.1 gallons of TPH-g was removed from the subsurface during the four days of operation. 6.2.1. Low Vacuum SVE Extraction Wells GTI proposes utilizing the two exiting extraction wells VEW-1 and VEW-2. As previously discussed, these two wells were installed during the backfill operations of the contaminated soil excavation in 2002. Each well is constructed of four-inch diameter drain pipe with rows of 3/8-inch diameter holes from 1-foot bgs to the total depth of 10-feet bgs. It is anticipated that most of the removal will result from extraction in VEW-1, which is located in the east area of the gravel backfill area, near the core of the soil and groundwater plume. VEW-2 is expected to provide a means to extract vapors in the west area of the gravel backfill area(and surrounding soils), and will allow the system to be operated in pulse mode. 6.2.2. Low Vacuum SVE Piping Vapors will be extracted from the two vertical extraction wells VEW-1 and VEW-2. As shown on Sheet 2 of the Remedial Improvement Plans, two-inch diameter schedule 40 pvc will be used to convey vapors from the vapor extraction wells to the SVE equipment. The extraction piping will be buried in a trench with a minimum of 12-inches of cover as shown on Sheet 3. The extracted air will first pass through a liquid knockout unit to protect the blower against rapid wear from excess moisture and sediment particles. 6.2.3. Low Vacuum SVE Equipment The low vacuum SVE equipment will consist of: • Vapor extraction from two vertical extraction wells and associated piping; • Manifold constructed near the equipment enclosure with valves so that flow rate can be controlled; • Liquid knockout unit; • Electric blower motor capable of up to five inches of Hg vacuum. • Activated Carbon Units (two 55-gallon drums in series). 6.3. Potential Permits Required GTI anticipates that the following permits will/may be required for the proposed work: • Drilling Permit A permit and fees will need to be obtained from SJCEHD for the advancement of two air sparge points. • Authority to Construct Geological Techdcs Inc. 18 4252 RAP.docx