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2022 ANNUAL GROUNDWATER MONITORING REPORT TEICHERT AGGREGATES AND GRANITE CONSTRUCTION VERNALIS AREA Wells are purged until indicator parameters (temperature, pH,and electrical conductivity) have stabilized prior to sample retrieval. Stabilization is defined as consecutive readings where parameters do not vary by more than 5 percent.Visual (color,occurrence of solids),olfactory(odor)and other observations(e.g.,wellhead conditions,well access,ground conditions,weather)are noted as appropriate.The following instrumentation is used by LSCE staff: • Depth to water:Solinst and/or Powers electrical sounder(Water Level Indicator) • pH,temperature, electrical conductivity(EC),dissolved oxygen (DO), oxygen reduction potential (ORP),total dissolved solids (TDS): YSI Pro DSS instrumentation • turbidity: YSI Pro DSS instrumentation or Oakton T-100 portable turbidity meter The calibration and maintenance of instrumentation is conducted following the manufacturers' instructions and guidelines using appropriate standard solutions and procedures and at manufacturer recommended intervals.The electrical sounder and temperature probe are factory calibrated and do not require calibration by the user. Samples are collected in laboratory-supplied bottles with no headspace. Bottles are labeled with laboratory-supplied labels, immediately placed on ice, and kept in a dark ice chest for transport to the laboratory. 4 MONITORING RESULTS Quarterly groundwater level and quality monitoring commenced in March 1994 to characterize pre- mining groundwater conditions in the area and facilitate the continued evaluation of local groundwater conditions.Also,as part of Teichert and Granite's approved plan to dry-pit mine,groundwater level monitoring provides the necessary information to establish and maintain a buffer between the base of mining and groundwater. Mining of the Teichert Vernalis Central phases began in 1998 and has proceeded to varying depths up to 150 feet bgs through phase 4,with phases 2 through 4 currently used as siltation ponds. Currently,the mining of the Teichert Vernalis West and East phases has progressed to an approximate depth of 120 feet bgs in phase A5. Active mining operations in Phase Al are planned to begin later in 2023. Granite has completed mining of Phase 1 to a depth of 150 feet and has reclaimed Phase 1 with pond fines.The southern portion of Phase 2 is currently being mined.As of 2021, Phase 2 has been partially mined to a depth of 150 ft. 4.1 Groundwater Levels Long-term fluctuations of shallow groundwater levels in the area are depicted by the hydrograph for Well 4S/6E-5A1(Figure 4),which has been monitored semi-annually by the California Department of Water Resources (DWR)from 1960 through 2020(typically in the winter, i.e.,January, February,or March;and in late summer/early fall, i.e., in September or October)and quarterly for Teichert's quarry excavation monitoring program since 1994.The lowest historic water level, i.e., 69 feet above mean sea level(msl),was recorded in early 1962,at the end of two consecutive critically dry years(DWR Water LUHDORFF&SCALMANINI CONSULTING ENGINEERS 4