WORK PLANS - Laserfiche WebLink

Home Browse Search

t w V Vapor Monitoring Probes Three vapor monitoring probes will be installed at different depths to target the silt/clay and sandy zones. The probes will be used to collect vapor samples and pressure/vacuum readings to monitor the effect of SVE. These probes may be nested in a single borehole should space constraints preclude installation at different radial distances from the extraction wells: P-1, 1-inch diameter, PVC Schedule 80, 0.020 slot size, screened — 15-20 feet. P-2, 1-inch diameter, PVC Schedule 80, 0.020 slot size, screened —25-30 feet. P-3, 1-inch diameter, PVC Schedule 80, 0.020 sot size, screened — 30-35 feet. Probe P-2 is to be installed within the "tighter' silt/clay strata, so the depths of 25-30 feet are anticipated given current review of the available geologic cross sections. The well depths will be adjusted to the strata contacts observed in the field to position the wells and probes. SVE Test Description The equipment arrangement is shown schematically on Figure 3 — SVE Test Schematic. We anticipate the following equipment will be utilized: A 3-horsepower or higher positive displacement blower or a regenerative blower rated for at least 50 standard cubic feet per minute (SCFM) at a vacuum of 8-inches mercury, one or two 200-pound vapor phase carbon vessels, differential pressure gauges indicating pressure/vacuum in inches of water, differential pressure or variable area flow meter 0-50 SCFM, Tedlar® bags, 2-inch Schedule 40 PVC piping or 2-inch hose with quick connect coupling and appropriate wellhead fittings. It is anticipated that the test duration will be approximately four hours (2-hour/well). Test measurements will taken every 30 minutes or so. We will measure extraction well air flow-rate, extraction well vacuum, and baseline and test vacuum/pressure at probes P-1 through P-3. Four extracted air samples (2 per extraction well) will be analyzed for the COCs. These vapor samples collected in Tedlar® bags will be analyzed by EPA Method 8280. Grab vapor samples collected from the soil probes will be analyzed for TPH and % oxygen by handheld instruments including a photoionization detector and a LEL meter. Test Results and Report A report of the findings of this SVE test will be prepared for submittal to PHS EHD. The report will include the well and probe construction details, site maps and geologic cross sections. The report will describe and interpret test results including air flow-rates, well and probe vacuum, and soil gas analytical data. We will analyze the test data and develop estimates of the SVE radius of influence, initial COG removal rates, and effectiveness of SVE in the soil strata tested. We will assess the feasibility of using SVE as an interim remediation measure based on the analysis of test data and develop additional recommendations for full-scale implementation if appropriate. Revision I Page 2 of 3