Laserfiche WebLink
31 January 2013 <br />AGE-NC Project No. 02-0926 <br />Page 10 of 21 <br />The nearest surface water feature in the vicinity of the property is McLeod Lakeated <br />approximately 5,000 feet to the southwest and cross-gradient of the site. It is unlikely that <br />water in McLeod Lake Is -contaminated by impacted groundwater from the site based on <br />its distance and direction (cross-gradient) from the site. <br />8.0. _HISTORICAL SOIL & GROUNDWATER CORRECTIVE ACTION <br />Interim Soil Vapor Extra-00 7 <br />Between 28 December 2010 and 22 August 2011, an SVE remediation system was <br />operated at the site. On 04 February 2011 the natural gas-fired, thermal oxidizer SVE <br />system was removed from the site and replaced with a granular activated carbon (GAC) <br />adsorption vessel SVE system to continuously apply an induced vacuum to well VW-1. <br />On 22 August 2011, the on-site SVE system was temporarily shut down for the <br />performance of a SVE rebound response test. The system was restarted for a period of <br />24-hours on 19 October 2011 and subsequently sampled on 20 October 2011 as part of <br />the SVE rebound test. <br />Results of the SVE rebound response test did not indicate any significant spike in vapor <br />concentrations had occurred, and generally appeared to be within the range of previously <br />encountered hydrocarbon concentrations. Based on results from the SVE rebound test <br />AGE concluded that asymptotic influent vapor concentrations had been reached, and <br />further SVE rennediation would be of little benefit to the site without performance of <br />conjunctive active ground water treatment. <br />Based on samples collected during operation of interim SVE, a cumulative total of 8,278.2 <br />pounds or 1,324.6 gallons of hydrocarbons as gasoline were extracted by the SVE system <br />between September 2010 and October 2011. <br />72-Hour 1AS Pilot Test <br />Between 19 December and 22 December 2011 an approximate 72-hour IAS pilot test was <br />conducted at the site. The IAS was accomplished utilizing monitoring well MW-6 (screened <br />70 to 75 feet bsg) as an active sparging point and pressure was supplied by an electric air <br />compressor to inject air beneath the water table at well MW-6. The on-site SVE system <br />was utilized to recover vapor from well VW-1 throughout the duration of the pilot test. <br />During the 72-hour IAS pilot testing period, the mass of hydrocarbons extracted by the SVE <br />system was calculated to be 18.3 pounds, or equivalent to a volume of approximately <br />Advanced GeoEnvironmental, Inc.