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SummerHill Apartment Communities 10391.000.000 Rollins Road-Carolan Avenue,Burlingame November 19,2014, Revised January 14,2015 approximately 20 to 30 gallons of hydraulic fluid. During review of the SMCEHD files and Fire District files, records documenting the installation or removal of hydraulic lifts from the Property addresses were not found. Based on the historical use of the Site for automotive services, the gaps in the records, and experience with similar sites, it is anticipated that with a Property of this size,remnant tanks and undocumented buried structures could be encountered during the Site redevelopment process. 3.0 EXTENT OF SOIL IMPACTS Review of the earlier environmental studies undertaken across the Site found that it is unlikely that a pervasive environmental condition exists at the Property. However, residual environmental impact likely occurs in the locations specified in the reports. The Site has had numerous sampling programs performed in the past as shown in Figure 3. Given that the Site operated with businesses that provide automotive maintenance and repair services and has a history of the use of numerous underground and above ground storage tanks, it is reasonable to expect minor localized impacts. The areas with possibly impacted material can generally be described as the former UST areas and the vehicle maintenance and repair shops that maintained hydraulic lifts. Review of laboratory test results found detectable concentrations of total petroleum hydrocarbons and heavy metals in the soil. Based on a review of the laboratory analyses, heavy-range TPH constituents, including diesel and motor oil, are the chemicals of potential concern(COPC). As requested by San Mateo County Environmental Health Department, TPH as gasoline and BTEX will also be considered as COPCs around the former fuel UST. The TPH impacts appear to generally be confined within 8 to 10 feet of the ground surface. Volatile organic compounds (VOCs), semi-VOCs, and metals had reported concentrations below applicable screening levels that would not be expected to impact future Site development; however, these COPCs will also be analyzed as part of initial screening of contaminated areas encountered during grading and construction. Temporary construction workers will not have prolonged exposed to potential COPCs that would necessitate additional activities besides typical level D modified personal protective equipment, such as gloves,boots, safety vest, etc. 4.0 EXTENT OF GROUNDWATER IMPACTS Given the proximity to the Bay and its brackish quality,we do not expect groundwater to be used as a potable water supply, nor would it represent a health risk to future occupants. The TPH levels found in the groundwater require that dewatering plans for the underground structure be implemented during construction and should consider possible onsite treatment prior to disposal to the city's sewer system. A small-scale carbon filtration system could be considered for water treatment. A skid-mounted or trailer-mounted filtration system could be used during construction -3- ENGEO —Expect Excellence --