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expected to continue to decrease. The site meets the criteria of the Low-Threat Closure Policy (Attachment 3). Extent defined A soil investigation conducted in March 2011 found that TPH-d was detected in all soil borings between 9 and 12 feet bgs, with maximum concentrations in GP-15 at 14,000 mg/kg (Figure 2), in a report dated 30 March 2011. The installation of upgradient monitoring well MW-4, soil borings and grab groundwater samples collected in October 2015 showed the groundwater plume does not extend off-site. Analytical results are presented in AGE’s Remediation Well Installation & Additional Site Assessment Report dated 29 December 2015 Threat to Groundwater Soil and groundwater sampling showed that contamination was limited to a depth of 20 feet below ground surface (bgs), and existing dissolved TPHd concentration in the water table aquifer is defined and decreasing. Groundwater usage on site is prohibited by the City of Lathrop and regional groundwater use is pumped from the Deep Zone aquifer at depths of 151 -218 feed bgs. Therefore, groundwater is not likely to be further degraded by residual TPH in near surface soils. Threat to Human Health In the most recent sampling event, no constituents were found in any of the monitoring wells. Soil and groundwater sampling conducted in 2015 showed the extent of contamination is limited to the spill area and has not migrated off site. Groundwater is not used for any purpose on site, therefore no threat to human health is expected from groundwater use. Residual impact on site is comprised of weathered diesel fuel and the potential level of volatility is expected to be insufficient to present hazards from soil vapor. Shallow soil samples collected in October 2015 show BTEX compounds are below residential criteria levels established in the LTCP. Planned development of the property will cover the area containing the residual TPH-d with warehouses and asphaltic parking lots. Data suggests the site meets Scenario 3 of the Petroleum Vapor Intrusion to Indoor Air criteria established in the Low-Threat Closure Policy (LTCP). Considering these circumstances, there does not appear to be a significant threat to human health. 30 Day Public Comment Period No comments were received during the 30 day comment period from 06 March 2020 – 06 April 2020. Conclusion The site meets the requirements of the Low-Threat Closure Policy for Underground Tanks. Based on the elimination of LNAPL from the groundwater table, the reduced