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Lynsey Sammons <br /> San Joaquin County Environmental Health Department <br /> RE:Vestis Facility,7679 Longe Street,Stockton,California <br /> of water lost during the three-day hydrostatic test, and the 12-inches of water loss occur within the 20- <br /> inches between the maximum basin perimeter and level to which the basin was filled for the three-day test. <br /> August 29 to September 1,2025,wastewater pit#1 hydrostatic leak test results <br /> Reading Date Time DTW Difference Loss Rate Monitoring <br /> (in) (in) (in/day) Interval <br /> (min) <br /> Day 0 8/29/2025 16:53 20.50 0.000 <br /> Day 1 8/30/2025 16:57 22.50 2.000 1.99 1444 <br /> Day 2 8/31/2025 16:53 23.00 0.500 0.50 1436 <br /> Day3 9/1/2025 16:58 23.31 0.313 0.31 1445 <br /> The three-day test slowed over time,which could indicate one of the following: <br /> • The data is similar to a soil infiltration test for a septic system.That is, as the soil becomes <br /> saturated,the soil's capacity to absorb additional water becomes less as the soil pore spaces fill, <br /> and the leak apparently slows. <br /> • Or that contents in the wastewater contain a mixture that over time acts as a sealant, e.g., acts like <br /> a sealant similar to pipe dope. <br /> To mitigate the leaks (Pittsburgh Tower and Tank) mobilized to the facility on September 12, 2025, to begin <br /> basin repairs. While preparing the basin for the lining process, one of the conveyance pipes entering the <br /> basin continued to allow a flow of water not allowing for completely dry conditions to be established and <br /> needed for the lining process. Although they attempted to mitigate this condition by inserting an inflatable <br /> bladder into the pipe. Unfortunately,this was not successful due to scale build-up in the pipe and the <br /> contractor had to cease the project until this condition could be rectified. Vestis is working on corrective <br /> actions for removal of the scale build-up so Pittsburg Tower and Tank can resume to project. They <br /> anticipate remobilization to occur by October 30tH <br /> The County requested soil testing to see if materials may have been released to the environment. Our <br /> proposed work plan recommends that investigation borehole(s) be installed using a hollow stem augur <br /> (that is, drilled by hand) as opposed to using a mechanical drilling rig (i.e. Geoprobe rig). With the concern <br /> being that using a mechanical drill rig will push through an underground utility or pipe with being noticed <br /> causing unintended damage. <br /> Given that portions of the leak appear to occur within the first 20-inches below the rim, we propose to <br /> collect a soil sample at 1-foot and 5-feet below the rim.The shallow sample will provide relative <br /> information in the potential "leak" area, and the deeper sample will indicate if any contamination, if <br /> present, persists with depth, or the soil column behaves like a septic system trickle filter and mitigates any <br /> total petroleum hydrocarbons released to soil as the impacted wastewater percolates through the soil <br /> column. <br /> To investigate the severity of the leaks,Vestis proposes the following steps: <br /> • Install a borehole adjacent to wastewater basin#1 at location shown in the attached figures. <br /> • Collect soil samples at 1-foot and 5-foot below floor surface. <br /> Page 2 <br />