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SummerHill Apartment Communities 10391.000.000 Rollins Road-Carolan Avenue,Burlingame November 19, 2014,Revised January 14,2015 across the site to pump and process the groundwater through a predetermined number of stages of increasingly fine filtration. Prior to grading, the developer should prepare a dewatering plan for the site to be implemented during construction, subject to review and approval by the City of Burlingame. The dewatering plan should include appropriate treatment requirements to provide that water from the site meets applicable pre-treatment standards prior to disposal into the city's sewer system. 5.0 REMOVAL ACTION OBJECTIVE The potential removal action objective (RAO) is to reduce the human risks associated with the COPCs in Site soils to a level that is acceptable for the planned future development and to allow for future unrestricted residential use of the Site. The development will consist of a significant engineered cut of up to 8 to 9 feet below the ground surface in the northern portion of the Site for the construction of the underground parking. The excavation will impact the near-surface soils on 1017, 1019, 1025 Rollins Road and 1020 and 1028 Carolan Avenue. Site grading in the southern portion of the site for the townhomes and pedestrian way will include minor cutting and filling of about 1 to 3 feet to establish the planned site grades. For geotechnical purposes and prior to placing fill,the upper 12 inches of material will be scarified. Based on the RAO, cleanup levels have been established that are protective of human health and the environmental and reduce the potential for exposure to the COPCs in soil encountered at the Site. 5.1 TOTAL PETROLEUM HYDROCARBONS AS DIESEL The Regional Water Quality Control Board's (RWQCB) environmental screening level (ESL) of 100 mg/kg will be utilized as the soil cleanup level for TPH-diesel in residential soils. Any soil encountered during demolition/construction exhibiting TPH-diesel concentrations exceeding the ESL will be excavated and properly disposed. 5.2 TOTAL PETROLEUM HYDROCARBONS AS MOTOR OIL Similar to TPH as diesel, TPH as motor oil concentrations will be compared to the RWQCB's ESL for residential soils of 100 mg/kg. Any soil encountered during demolition/construction exhibiting elevated TPH-motor oil concentrations exceeding the ESL will be excavated and properly disposed. 5.3 TOTAL PETROLEUM HYDROCARBONS AS GASOLINE Similar to TPH as diesel and motor oil, TPH as gasoline concentrations around the former UST area will be compared to the RWQCB's ESL for residential soils of 100 mg/kg. Any soil encountered during demolition/construction exhibiting TPH-gasoline concentrations exceeding the ESL will be excavated and properly disposed. -4- ENGEO —Expect Excellence—