WORK PLANS - Laserfiche WebLink

Home Browse Search

Revised Workplan-Additional Site Investigation for PFAS BSK Project E20-016-01F Stockton Metropolitan Airport(SCK) March 1, 2023 Stockton, California Page 18 and between former borings TW-4 and B-18.At the request of the CVRWQCB in their letter dated January 13, 2023, one (1) of the four (4) DPT borings placed around former boring B-8 will be advanced to 40 ft bgs and sampled for chemical analysis every 5 ft once the 10 ft sample has been collected. Note,the DPT boring around B-8 selected to advance to 40 ft bgs will depend on which location will impact Airport activities least.Additionally,as requested in the CVRWQCB letter dated January 13,2023;soil samples will be collected in three(3)monitoring well borings(e.g., MW-2, MW-3 and MW-4)within the capillary fringe (approximately 40 ft bgs)to characterize PFAS in the capillary fringe below SCK property. For exact proposed locations and depths of DPT borings in PRA 1 and PRA 2, please refer to Figure 5 and Figure 6, respectively. Samples for chemical analysis would be labeled and placed into a chilled cooler immediately following collection. Samples would be transported under chain of custody protocol to an ELAP approved laboratory for analysis. 6.1.2.2 Monitoring Well Construction BSK will install four(4) groundwater monitoring wells to establish gradient and gradient direction below the SCK property during the First Phase of investigation.The monitoring wells will be installed with respect to anticipated gradient flow (east-northeast)2 underneath the SCK property. Figure 2 shows a site plan with proposed monitoring well locations. Wells will be designed and constructed with respect to depth to groundwater information from BSK's June 2020 PSI and known regional fluctuations in groundwater levels. The monitoring wells will be constructed according to the following: • Well pipe constructed of 2-inch diameter, Schedule 40 (SCH 40) polyvinyl chloride (PVC) • The wells will be installed to a total depth of approximately 60 ft bgs • 0.010-inch slotted well pipe from 60 ft bgs to 40 ft bgs wrapped with wire mesh which contains a prepacked sand filter pack. • Traffic-rated flush mount well box installed approximately 1-inch above surface grade, with locking well cap installed in well pipe. Following the installation of the four (4) groundwater monitoring wells during the first phase of investigation, monitoring wells would be allowed to sit for at least 48 hours prior to development. Following development,the monitoring wells would be allowed to sit for an additional 48 before purging, and subsequently obtaining groundwater samples for chemical analysis. z Historical groundwater flow information is available under Case Number T0607700159 in GeoTracker (KM C554e-20140613134325(ca.gov))