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03 June 2021 <br />Project No. 21-6431 <br />Page 6 of 15 <br />Advanced <br />An Employee -Owned Cor.,,> ,�, <br />. 4 <br />4.1. GROUNDWATER DESCRIPTION FOR THE GENERAL AREA <br />According to the State of California Department of Water Resources (DWR) Sustainable <br />Groundwater Management Act (SGMA) Data Viewer, Seasonal Report for Spring 2020, <br />depth to groundwater at the site is approximately 75 feet below surface grade (bsg). <br />Between 2011 and 2019, depth to groundwater at the site has fluctuated between 55 and <br />95 feet bsg. Groundwater flow direction locally appears to be to the northeast. <br />Groundwater was not encountered in the 42 -inch -deep percolation test hole advanced on <br />17 May 2021. <br />4.2. GROUNDWATER CONTAMINATION IN THE AREA OF THE SITE <br />The immediately adjacent and outlying land use for the parcel is residential. Potential <br />groundwater contamination can occur from several sources including leaking <br />underground storage tanks, septic systems, agricultural activities, dairies, and stormwater <br />infiltration. <br />A review of the California Department of Toxics and Substance Control (DTSC) <br />EnviroStor Database and the Geotracker Web Site did not reveal any Leaking <br />Underground Storage Tank (LUST) sites within 0.5 miles of the site. <br />4.3. ON-SITE EXISTING WELL DESCRIPTION <br />There is one existing domestic water supply well on the property. The well was installed <br />in June 1988 (88-1447 and 88-1448). The well is composed of 6 -inch diameter polyvinyl <br />chloride (PVC) casing installed in a 10 -inch diameter bore hole to a total depth of 220 feet <br />bsg. The well grout seal is installed to 50 feet bsg. The onsite well provides potable water <br />to the existing residence and subject property. A copy of the well permit is included in <br />Appendix B. <br />4.4. CONSTITUENTS BEING TESTED FOR IN THE WATER SAMPLE <br />Nitrate (NO3) constituents and 1,2-dibromo-3-chloropropane (DBCP) were tested in the <br />existing groundwater supply well at the subject property. <br />4.5. GROUNDWATER SAMPLE COLLECTION <br />On 18 May 2021, a sample of the drinking water provided by the current groundwater <br />supply well at 6055 Garnica Court, Stockton, California was collected in an unpreserved <br />0.5 -liter plastic container and two volatile organic analysis (VOAs) vials. The groundwater <br />sample containers were properly labeled, placed in a chilled container, and transported <br />