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Introduction This report presents the design for an onsite wastewater treatment system (OWTS) to serve a new Gate Building within UPRR's Lathrop Intermodal Terminal located at 1000 E. Roth Road, French Camp, CA. Appendix A contains a site location map showing the new Gate Building. Design Criteria The proposed onsite wastewater treatment system is designed in accordance with the "San Joaquin County Onsite Wastewater Treatment Systems Standards",January 20, 2017. Site Information As part of the UPRR Lathrop Intermodal Expansion project a new Gate Building will be constructed approximately 2,100 feet south of Roth Road and 290 feet west of Intermodal Way. The Gate Building will be approximately 6,048 SF in size and will serve as the administration building for the terminal. The proposed Gate Building will be occupied for 24hrs and seven days a week to coincide with UP operations. It is anticipated there will be 3 shifts with 10 people per shift occupying the Gate Building netting a total occupancy of 30 people per day. Utilizing Table 6.6 of the San Joaquin County Onsite Wastewater Treatment Systems Standards for "Day workers at school/offices (per shift)" the anticipated average daily flow based on 30 people per day at 30 gallons per person will be 900 gallons per day. The proposed onsite wastewater system will consist of a septic tank and subsurface dispersal field with 4" perforated PVC leach lines. The dispersal field is located approximately 218 feet north of the Gate Building and meets the required setbacks established in the San Joaquin County Onsite Wastewater Treatment Systems Standards. Percolation Testing & Groundwater Elevation A percolation test was performed by Shannon &Wilson, Inc. in May of 2019. The test was performed approximately 1675' South of Roth Road and 270' west of Intermodal Way within UPRR Row within the proposed sewage disposal area. The results of the percolation test showed a percolation rate of 13.3 min/in. Appendix B contains the results of the percolation test. The groundwater elevation was also observed in a geotechnical investigation performed by Shannon and Wilson Inc. in 2011 and supplemented in 2022. The groundwater was observed to be 15 feet to 21 feet below the existing ground surface corresponding to an approximate elevation range of+0.5 feet to +8.5 feet MSL. Per Table 1.10.2 of the San Joaquin County Onsite Wastewater Treatment Systems Standards, the minimum soil depth from the bottom of the dispersal system to the groundwater table for percolation rates 5 min/in <_ 30 min/in shall be 8 feet. The bottom of the proposed dispersal system will be approximately 20.74 which meets the requirement set forth in Table 1.10.2. Page 3 of 6