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A - -- 1117 Lone Point Avenue, Suite 201 v Modesto, California 95351 209-579-2221 ,•: � Fax : 209- 579-2225 -ya ASSOCIATES%T I N C . Each sparge well will contain two nested ozone sparging points that will be screened within specific lithologic intervals of approximately 60 to 65 and 85 to 90 feet bgs. The sparge points will consist of 2- inch inside diameter schedule 80 PVC well screen and casing with approximately five feet of 0.010 inch slot screened PVC. An 18-inch long and one-inch diameter porous (25 micron pore size) PolyVinylidine DiFluoride (PVDF) In-situ Oxidation Point (IOP)Q will be placed inside the screened portion of each sparge well . The IOP, designed and mamttactured by H2O Engineering, is constructed from ozone- resistant PVDF, a highly non-reactive and pure thermoplastic fluoropolymer also known as Kynae. Within the well box, the well casing will be fitted with a water/air tight wellhead connection (WHC) designed from schedule 80 PVC material that will be used to facilitate sparging. A sand pack will be placed in the annulus of the wells extending fi-om the bottom of the well screen to approximately two to tluee feet above each respective well screen. Approximately three feet of hydrated bentonite will be placed on top of the sand pack and hydrated with potable water. A bentonite cement slurry mixture will be tremi grouted fi`om the top of the bentonite layer of the shallowest well point to approximately two feet below surface grade. Surface completions will consist of a watertight bolt-down wellhead set in Portland cement. Drill cuttings will be collected and stored on site in DOT-approved 55 - gallon drums and will remain on-site pending proper waste profile characterization and disposition at a State permitted landfill or TSD facility. Appendix A shows the proposed well construction details. Sample Analyses Three soil samples will be collected from the borehole of each sparge well for geotechnical analyses at approximately 60 feet bgs (within the sandy water bearing unit), 70 feet bgs (within the clay unit), and 85 feet bgs (within the sandy water bearing unit) . Each soil sample will be collected in brass sleeves or acetate sleeves, whichever method is best suited to capture au undisturbed Sample . Each sample will be analyzed for total organic carbon using the Walkley-Black method and particle size analysis using ASTM Method D422M and AST Method D4464M. The data obtained from these analyses will be useful regarding remedial design considerations. Baseline Sampling and Monitoring The soil samples collected from 60 and 85 feet bgs will be analyzed for total chromium by EPA Method 6020 and hexavalent chromium by EPA Method 7199. Prior to start of the pilot test, baseline measurements of static water level , dissolved-phase fuel hydrocarbon concentrations, dissolved total chromium and hexavalent chromium, bromate, pH, temperature, dissolved oxygen (DO), and oxidation- reduction potential (ORP) will be collected from selected observation wells (MWI , MW2, MW4, MW5, and MW12). These monitoring parameters will be measured periodically for the duration of the pilot testing. Groundwater samples will be analyzed weekly during the test period for hexavalent chromium and broinate. The SICEHD will be notified immediately of changes above baseline concentrations with respect to hexavalent chromium and bromate. As deemed appropriate, other parameters may also be monitored . The groundwater samples collected from selected nearby monitoring wells prior to the start and at the end of the pilot testing will be submitted under chain-of-custody procedures to a State-certified laboratory. Ozonic Pilot Testing Workplan — Former Slocklon Tart Company ATC Associates Inc. S:...128349\ Reports\Ozonc Pilot Testing WP ATC Project No. 54.28349.0001 5