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TAOC 6th Street Property - 3 - 7 February 2014 Human Health Screening Evaluation by the report and does not apply to current site use (unauthorized trespassing) and... Per DISC, imminent and/or substantial endangerment to human health or environment does not presently exist at the site under its current condition and use (DISC, 2013). Ecological Screening Evaluation A review of the California Department of Fish and Game's 2013 California Natural Diversity Database (CNDDB) by AMEC indicated that three special status species were identified within a one-mile radius of the Site. None of these three are currently listed as threatened or endangered and none were identified within 2,000 feet of the Site. The Site is not developed, but it is planned for potential development as a residential community in the future. The Report concluded that based on the CNDDB assessment, a threat to sensitive species does not appear to exist. Comments My comments regarding the HHESE are as follows: • AMEC's report did not specify a plan for mitigation of high PAH concentrations near boring TRY-29 and how that would effectively reduce or minimize the health risk exposure associated with those near surface chemicals. • Removal of the PAH-affected soil at or near five feet bgs near boring TRY-29 and submission of an HHESE addendum once affected soil is removed could allow opportunity for future unrestricted use within OU-5. Staff would review any remedial action workplans and provide comments for the HHESE addendum. • Part of managing the risk for the Site includes the preparation of a soil and groundwater management plan (SGMP), which Chevron needs to submit. Because residual crude oil in soil and groundwater will remain at the Site, the SGMP designates Chevron as the responsible party and serves as a guideline to Chevron for handling soil affected by the residual crude oil as a result of leaks from the historical pipelines which may be encountered by the property owner(s) during future Site activities. However, preparation and submission of a SGMP should be delayed until the effects of high PAH concentrations are mitigated or remediated. Summary The risk assessment appears to present adequate data to support the conclusion that there is minimal risk exposure to human health as well as the environment under the conditions investigated within the OU-2 investigative area. The lessening of the impacts of the PAH compounds identified within OU-5 in a five feet bgs sample at boring TRY-29 may be difficult and time consuming and thus mitigation of those conditions at that location may not be effectively accomplished. As such, considering the depth of occurrence at five feet bgs, removing the affected soil may be a more appropriate means to provide future unrestricted land use of the property within OU-5. AMEC's report did not specify a mitigation plan of the high PAH concentrations at five feet bgs reported in boring TRY-29. If removal of the PAH affected soil is selected as an alternative, a time schedule and workplan will need to be submitted.