WORK PLANS - Laserfiche WebLink

Home Browse Search

i Mr. James Barton, PG 24 April 2014 Page 2 and First Quarter 2014 Groundwater Monitoring Report, submitted to RWQCB on 26 March 2014 (Geosyntec, 2014a), Geosyntec proposed installing two groundwater monitoring wells downgradient from the source area, one screened in the A-zone sand (approximately 30 to 40 ft bgs) and the other screened in the B-zone sand(approximately 60 to 70 ft bgs). Representatives of Geosyntec and the RWQCB met at the RWQCB office in Rancho Cordova on 11 April 2014 and agreed that(1) a third monitoring well, screened across the water table, shall be added to the proposed well cluster, and (2) an investigation comprised of a transect of four grab groundwater sampling locations with samples collected from distinct borings at first water, the A- zone sand, and the B-zone sand, shall be conducted to supplement groundwater monitoring data from the offsite well cluster. The proposed well cluster and grab groundwater sampling locations are shown in Figure 2. Geosyntec and the RWQCB also agreed on the following points: i the CPT/grab groundwater investigation will be adaptive in nature — if B-zone samples exceed water quality 'objectives for toluene (i.e., the California Primary Maximum Contaminant Level [MCL]3 and the California Public Health Goal for Drinking Water4 of 150 micrograms per liter [µg/L]) in samples from the B-zone;deeper groundwater samples will be-collected; • groundwater monitoring wells can be sampled on a bi-monthly basis to evaluate concentration trends over time; and • RWQCB will provide documentation acknowledging completion of soil excavation in the source area. 3 California Department of Public Health,2014.Maximum Contaminant Levels and Regulatory Dates for Drinking Water, U.S. EPA vs California. 13 February. 4 State Water Resources Control Board,2011.A compilation of Water Quality Goals, le Edition.April. Offsite Characterization Workplan engineers I scientists I innovators I