SR0085240 (4) - Laserfiche WebLink

Home Browse Search

Work Plan for Additional Subsurface Investigation Former Helena Chemical Facility July 13,2020 Page 7 including the depth intervals of the screen, sand pack, and seals. A generalized well construction diagram is included as Figure 7 (Appendix A). 5.3 MONITORING WELL SURVEYING Following installation of the monitoring wells, the wells will be surveyed to determine the location and elevation of the well collar in order to comply with AB2886 (Water Code sections 13195 — 13198). The well collars will be surveyed with a vertical accuracy of 0.01 foot to a NAVD 88 or NGVD 29 datum, and with a horizontal accuracy of 0.03 foot to a NAD 83 datum. The measuring point for water-level measurements will be marked on the well collar. Well survey data will be submitted in the required electronic deliverable format to the State Water Resources Control Board's GeoTracker database. 5.4 GROUNDWATER MONITORING WELL DEVELOPMENT AND SAMPLING At least 48 hours following installation, the monitoring wells will be developed by surging, bailing and pumping the groundwater in the well until the discharge water is relatively free of sediment (clear to the unaided eye). The monitoring wells will be purged until the temperature,electrical conductivity,and pH of the water have stabilized, and with a goal of reaching turbidity less than 5 NTU. All well-development equipment will be cleaned prior to use by washing in a solution of laboratory-grade, non-phosphate detergent and deionized water, and by double rinsing with deionized water. The groundwater purged from the well during development will be containerized in 55-gallon drums, sealed, labeled, and left on Site to await disposal pending results of laboratory analyses. The new groundwater monitoring wells will be sampled quarterly along with the other Site groundwater monitoring wells in conjunction with Monitoring and Reporting Order No. R5-2017-0817 (MRO) and will be sampled during the next groundwater monitoring event anticipated to occur in September 2020. 5.5 LABORATORY ANALYSES Soil and groundwater samples selected for laboratory analyses will be submitted to BC Laboratories(ELAP #1186)under chain-of-custody protocol and analyzed for the constituents listed in the table below. Table 1—Proposed Soil and Groundwater Analyses Matrix Target Detection Analytical Sample Container Preservative Hold Analyte Limit Method Time Soil Nitrate-N 0.26 mg/kg EPA 300.0 2-inch brass/SS sleeve 4°C 28 days Soil 1,2,3-TCP 0.0023 mg/kg EPA 8260B 2-inch brass/SS sleeve 4°C 14 days Soil 1,2-DCP 0.0019 mg/kg EPA 8260B 2-inch brass/SS sleeve 4°C 14 days Soil 1,3-DCP 0.0017 mg/kg EPA 8260B 2-inch brass/SS sleeve 4°C 14 days Groundwater Nitrate-N 0.024 m /L EPA 300.0 1,000 ml plastic bottle 4°C 48 hours Groundwater 1,2,3-TCP 0.00053 gg/L SRL 524M (3)40 ml amber 4°C 14 days un reserved VOA vials Groundwater 1,2-DCP 0.13 gg/L EPA 8260B (3)40 ml amber 4°C,HCl to pH<2 14 days reserved VOA vials Groundwater 1,3-DCP 0.14 gg/L EPA 8260B (3)40 ml amber 4°C,HCl to pH<2 14 days reserved VOA vials Notes:mg/kg=milligrams per kilogram=parts per million(ppm);mg/L=milligrams per liter=ppm; gg/L=micrograms per liter=parts per billion(ppb);°C=degrees Celsius;1,2,3-TCP=1,2,3-Trichloropropane;ml=milliliter;VOA=volatile organic analysis;HC1=hydrochloric acid;Nitrate-N=Nitrate as Nitrogen; 1,2-DCP=1,2-Dichloropropane; 1,3-Dichloropropene Laboratory results will be evaluated for accuracy, reliability, and repeatability by confirming that the laboratory's matrix spikes, surrogates,and duplicates fall within prescribed limits. �li CONDOR