Laserfiche WebLink
2022 ANNUAL GROUNDWATER MONITORING REPORT <br /> TEICHERT AGGREGATES AND GRANITE CONSTRUCTION <br /> VERNALIS AREA <br /> 5 SUMMARY <br /> Quarterly groundwater level and quality monitoring of two identified aquifer zones(a shallow and a <br /> deep zone)commenced in 1994 and mining of the Vernalis Central area commenced in 1998. Water <br /> level data, collected semi-annually from 1960 through 2020 by the California Department of Water <br /> Resources, are also available for one shallow zone well. <br /> Groundwater levels in the shallow wells have declined an average of approximately 25 feet to the lowest <br /> levels since the period of record began in 1994. Groundwater elevation contour maps indicate relatively <br /> steady shallow groundwater flow in easterly to southeasterly directions over the period of record. <br /> Groundwater levels observed in the deep wells are typically lower than in the shallow zone and exhibit <br /> greater seasonal and annual fluctuation than groundwater levels in the shallow wells due to increased <br /> aquifer confinement and pumping stresses. In the early 2000's,groundwater levels in the deep zone <br /> noticeably declined, likely in response to reported increased pumping stress and overall dry conditions. <br /> In the mid 2000's,substantial recovery of groundwater levels occurred, however,seasonally high-water <br /> levels remained below those observed in the mid to late 1990s. Since 2013,groundwater levels in the <br /> deep wells have approximately declined an average of about 100 feet. <br /> The groundwater quality record documents stable conditions in both the shallow and deep aquifer <br /> zones. Shallow groundwater is generally of Ca-Na/HCO3-CI or Na-Ca/HCO3-CI type and deep <br /> groundwater is of Ca-Na/HCO3-SO4 or Ca-Na/SO4-HCO3 type.The overall content of soluble minerals is <br /> slightly higher in shallow zone groundwater than in deep zone groundwater. Elevated nitrate <br /> concentrations in groundwater,documented since pre-mining times to the present, are most likely <br /> attributable to historical and ongoing agricultural land use in the area. In summary,the existing data <br /> record shows no indication that mining operations have changed groundwater quality to date. <br /> LUHDORFF&SCALMANINI <br /> CONSULTING ENGINEERS 9 <br />