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Soil Suitability /Nitrate Loading Study Irerracon <br />JPM ci Lathrop, California <br />May 24, 2022 in Terracon Project No. NA227026 <br />1.3.7 Expected On -Site Maximum Septic Tank Usage <br />Commercial Land Use <br />According to Mr. Drivon, the proposed commercial facility will be occupied seven days per week, <br />from 4:30 AM to 7:00 PM (14.5 hours) and include two shifts year-round. Mr. Drivon indicated up <br />to 100 employees may be on site during a single shift at full buildout. Mr. Drivon indicated Phase <br />will include approximately 40 employees per shift. Visitors are not anticipated. Based on the <br />review of the OWTS Manual, the flowrate for the proposed commercial facility is 15 -gallons per <br />8 -hour day, similar to an industrial building with no food cafeteria. Employee effluent was <br />calculated as follows for a 9 -hour day: 15 gpd / 8 hour day = 1.875 gallons per hour x 9 hours = <br />16.875 gpd. <br />Table 4. <br />Proposed Commercial On -Site Maximum Septic Tank Usage <br />Gallons per day (gpd) <br />The total maximum daily flow rate for Phase I and proposed Septic System 1 is 1,275 gpd. Peak <br />flow rates will occur between 11:00 AM and 1:30 PM where up to 80 employees are anticipated <br />to be onsite. <br />The septic system design should be based on the San Joaquin County On -Site Wastewater <br />Disposal Standards or other engineering recommendations. <br />1.4 Groundwater Information <br />1.4.1 Groundwater Depth and Gradient <br />Groundwater was encountered at approximately 3.83 feet bgs within our soil profile boring (near <br />B5) which was hand augered to 5.0 feet below grade surface (bgs). Groundwater was not <br />encountered in our soil profile / percolation test boring (B1) which was advanced to 6.5 feet bgs. <br />According to the California Department of Water Resources Sustainable Groundwater <br />Management Act (SGMA) Data Viewer, depth to groundwater and elevations were not available <br />for the site. Based on a review of the State of California Well Completion Reports, groundwater <br />Responsive in Resourceful ■ Reliable 7 <br />Average <br />Average Effluent <br />Maximum <br />Proposed <br />Shift <br />Number of <br />Quantity per <br />Septic Tank <br />Septic <br />Phase /Shift <br />Hours <br />Shift <br />Shift Times <br />Employee <br />Usage <br />System <br />per shift <br />d <br />d <br />Phase I / Shift 1 <br />9 <br />4:30 AM — 1:30 PM <br />40 <br />16.875 <br />675 <br />I <br />Phase I / Shift 2 <br />8 <br />11:00 AM — 7:00 PM <br />40 <br />15 <br />600 <br />Total Maximum Daily Flow Rate for Proposed Septic System 1 <br />1,275 <br />Gallons per day (gpd) <br />The total maximum daily flow rate for Phase I and proposed Septic System 1 is 1,275 gpd. Peak <br />flow rates will occur between 11:00 AM and 1:30 PM where up to 80 employees are anticipated <br />to be onsite. <br />The septic system design should be based on the San Joaquin County On -Site Wastewater <br />Disposal Standards or other engineering recommendations. <br />1.4 Groundwater Information <br />1.4.1 Groundwater Depth and Gradient <br />Groundwater was encountered at approximately 3.83 feet bgs within our soil profile boring (near <br />B5) which was hand augered to 5.0 feet below grade surface (bgs). Groundwater was not <br />encountered in our soil profile / percolation test boring (B1) which was advanced to 6.5 feet bgs. <br />According to the California Department of Water Resources Sustainable Groundwater <br />Management Act (SGMA) Data Viewer, depth to groundwater and elevations were not available <br />for the site. Based on a review of the State of California Well Completion Reports, groundwater <br />Responsive in Resourceful ■ Reliable 7 <br />