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19 May 2021 <br />Project No. 21-6435 <br />Page 5 of 14 <br />containing individual confining layers. The Modesto, Riverbank, Turlock Lake Formations <br />and overlying recent alluvium are the principal source of domestic groundwater in the <br />13,500-square mile San Joaquin Valley Groundwater Basin (Basin 5-22). This basin is <br />drained primarily by the San Joaquin River, which is approximately thirteen miles <br />southwest of the subject property. The nearest surface water feature to the site is the <br />Mokelumne River, which is approximately 3,700 feet east of the subject property. <br /> <br /> <br />4.1. GROUNDWATER DESCRIPTION FOR THE GENERAL AREA <br /> <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 15 to 20 feet below surface grade (bsg). <br />Between 2011 and 2019, depth to groundwater at the site has fluctuated between 15 and <br />30 feet bsg. Groundwater flow direction locally appears to be to the southwest. <br />Groundwater was not encountered in the 42-inch-deep percolation test hole advanced on <br />13 May 2021. <br /> <br /> <br />4.2. GROUNDWATER CONTAMINATION IN THE AREA OF THE SITE <br /> <br />The immediately adjacent and outlying land use for the parcel is general commercial and <br />medium density residential. Potential groundwater contamination can occur from several <br />sources including leaking underground storage tanks, septic systems, agricultural <br />activities, dairies, and stormwater infiltration. <br /> <br />A review of the California Department of Toxics and Substance Control (DTSC) <br />EnviroStor Database and the Geotracker Web site revealed seven (7) leaking fuel <br />underground storage tank (LUST) site within a half-mile radius of the subject property. All <br />seven (7) LUST sites have been closed for over ten years. Based on the status of the site <br />and the distance and direction from the subject property, the sites should not impact the <br />subject property. The review did not reveal any other sites of environmental concern <br />within a half-mile radius of the site. <br /> <br /> <br />4.3. ON-SITE EXISTING WELL DESCRIPTION <br /> <br />There is no existing domestic water supply well on the property. <br /> <br /> <br />5.0. SOIL PROFILE <br /> <br />An OWTS Permit was issued for the property by the EHD on 4 May 2021 to perform a <br />percolation test (Appendix B). On 13 May 2021, a 4-inch diameter hand auger was utilized <br />to advance a percolation test hole to 42 inches bsg, directly outside of the existing septic <br />system disposal field area.