SR0084222 (2) - Laserfiche WebLink

Home Browse Search

Work Plan, PFAS Site Inspection Naval Computer and Telecommunications Station Stockton, California Technical Approach 3-5 DCN: TRBW-0202-5183-0010 Appendix A). After collection, the samples will be placed in a cooler, chilled with ice, and shipped under chain-of-custody protocol to SGS Laboratories for PFAS analysis. Approximately 25% of the soil samples will be analyzed for TOC. Once complete, borings will be tremie grouted from the bottom to the surface with a portland cement/5 percent (%) bentonite mix. All decontamination water and drill cuttings will be containerized for IDW management according to the Waste Management Plan (Section 4). The total number of soil analysis samples for each analyte group is tabulated in Worksheet #18 and detailed in Worksheet #17 of the SAP. Worksheet #19 in the SAP presents a summary of the sample analysis, container types and volumes, preservation requirements, and holding times for the soil, sediment, groundwater, and IDW samples collected. 3.4.2 Direct Push Groundwater Sampling Groundwater samples will be collected from select direct push boring locations of each AOC. The rationale for sample locations is presented in Worksheet #17 of the SAP and samples will be labeled by field personnel as they are collected. The groundwater samples will be collected by installing 5 to 10 feet of three-quarter-inch polyvinyl chloride (PVC) screen connected to a riser pipe inside the direct push casing and pulling back the casing to expose the screen. If site conditions allow, a well volume may be purged prior to collecting a groundwater sample. A groundwater grab sample will be collected using temporary well procedures in accordance with SOP -009 (Attachment 1 in Appendix A). Groundwater samples will be logged on the Groundwater Sample Collection Field Sheet (Attachment 1 in Appendix A). The groundwater samples will be analyzed for PFAS compounds. Once sampling is complete, borings will be tremie grouted from the bottom to the surface with a portland cement/5% bentonite mix. All purge water and decontamination water will be containerized for IDW management according to the Waste Management Plan (Section 4). Before collection of groundwater samples, the depth of the static groundwater level will be measured in the groundwater monitoring wells using an electronic water level meter to evaluate groundwater flow direction. The depth will be measured in units of feet (to the nearest 0.01 foot) with respect to the top of each well casing, to determine the depth to water below ground surface. Water levels will be recorded on the Groundwater Sample Collection Field Sheet. The water level meter will be decontaminated prior to use and between each monitoring well. 3.4.3 Groundwater Quality Monitoring and Groundwater Sampling Groundwater monitoring wells will be purged using low-flow purging methods via a peristaltic pump prior to sample collection. The water level and total depth of each well will be measured before the start of purging. Measurements of pH, specific conductance, turbidity, temperatur e, oxidation-reduction potential, and dissolved oxygen will be made during purging and recorded on the Groundwater Sample Collection Field Sheet. If stabilization cannot be achieved after 30