AgdaPkt 2002-02-11 - Laserfiche WebLink

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November 5, 2001 53636.001 Mr. Peter Ingram City of Redwood City Page 7 We anticipate that three probes will be advanced at each CPT location to collect groundwater samples at three different water-bearing zones, located at approximately 12, 20, and 40 feet bgs. Sacrificial screened probe tips will be used, which allow the probe casing to be slightly retracted to facilitate sampling at each groundwater sampling interval. Grab groundwater samples will be collected using disposable bailers, or a peristaltic pump with new tubing, through temporary PVC well casing lowered into the probe holes through the retracted probe casing. We will decant groundwater samples into prepared sample bottles provided by the chemical testing laboratory. The shallow soil samples will be screened with an organic vapor meter (OVM) equipped with an 11.8 eV bulb to check for the presence of HVOCs. Soil samples will be retained in clear butyrate sample sleeves capped with Teflon sheeting and plastic end-caps. Probe holes will be retraction-grouted with neat cement through the probe casing upon completion of sampling activities. Sampling equipment will be steam-cleaned between sampling probes to minimize the potential for cross-contamination of samples. Soil cuttings and cleaning water will be stored in labeled 55-gallon drums disposed offsite once the chemical analytical results are received. We have not included costs in our proposal for disposal of the soil and water wastes. When the results of chemical testing of samples are received, we will advise the City of the possible disposal options and costs. Soil and groundwater samples will be stored in a cooled ice-chest, and delivered to a state-certified chemical testing laboratory under chain-of-custody. Samples will be analyzed for HVOCs using USEPA Method 8260 on a standard turnaround basis. Task 3 - Soil-Gas Survey The SFRWQCB requested a soil gas investigation at the former Davies parcel to assess the presence of gaseous-phase HVOCs in near-surface soils at and around the Old Navy retail clothing shop. The data collected from this soil gas survey will be used in preliminary human health risk assessment analyses. As described in SCI's Work Plan, Harding ESE will install 4 soil sampling probes at the former Davies parcel: one probe each along the north and south sides of the Old Navy building, one probe at the historical "hot spot" near former piezometer D-2 along ECR, and one probe approximately 250 feet northwest of the Davies parcel as a background sampling location. These locations are shown on Plate 1 of SCI's Work Plan. Depth-discrete soil gas samples will be collected at approximately 1 and 4 feet bgs at each location using a direct push sampling rig equipped with a soil gas profiler. Soil gas samples will be retained in Sumrna canisters, and delivered under chain-of-custody to a chemical testing laboratory certified by the State of California to analyze soil gas. Samples will be analyzed for HVOCs using EPA Method TO-14 on a standard turnaround basis. Task 4 - Sensitive Receptor Survey and Site Conceptual Model Pursuant to the requirements of the San Mateo County Groundwater Protection Program (SMCGPP), Harding ESE will perform a beneficial-use well survey for the area surrounding the site. As required by the SFRWQCB in their March 26, 2001 letter, the well survey will encompass an area within a V4-mile radius of the site. We will obtain listings of registered water wells within a V4-mile radius of the site