Reso13 PC 13-09 2859 Initial Study Mitigated Negative Declaration Kensington

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4.8.2.1 On-Site Hazardous Materials Impacts A discussed in Section 4.8.12, On-Site Sources of Contamination, there are no regulatory agency records or evidence of hazardous materials usage by the businesses on the project site other than typical small quantities of paints and cleaning supplies. The project,therefore,will not result in the exposure of construction workers or future site occupants to significant levels of hazardous materials based on past and present business operations on-site. (No Impact) Agricultural Land Uses It is reasonable to assume that the undeveloped area at the western end of the project site was likely part of a walnut orchard and that pesticides and other agricultural chemicals were used as part of the normal agricultural operations. Arsenic,lead, and dichlorodiphenyltrichloroethane (DDT)residue are commonly found in the soil from historic farming operations. During construction,the buildings and trees will be removed and the site graded. Once construction is complete, most of the exposed soil will be capped with the proposed building and parking lot. While a portion of the site will be landscaped,it is unlikely that contamination levels would exceed the industrial Environmental Screening Levels (ESLs). Nevertheless,there could be some direct exposure to the soil for future maintenance workers on the site. In addition,implementation of the proposed project could result in impacts to construction workers from exposure to soil contamination related to past agricultural operations. Impact HAZ-L• Implementation of the proposed project could expose construction workers and future on-site maintenance workers to contaminated soil. (Significant Impact) Mitigation and Avoidance Measures The project proposes to implement the following mitigation measures: MM HAZ-l.l: After demolition but prior to the issuance of grading permits, shallow soil samples shall be taken to determine if contaminated soil from previous agricultural land uses is located on-site with concentrations above established construction/trench worker thresholds. The soil sampling plan must be reviewed and approved by the Community Development Director, Department of Engineering, and the San Mateo County Health Department prior to initiation of work. MM HAZ-1.2: Once the soil sampling analysis is complete, a report of the findings will be provided to the Community Development Director and other applicable City staff for review. If no contamination is found or if contamination is found in concentrations below established thresholds,no further action is required and grading permits can be issued. MM HAZ-1.3: If contaminated soils are found in concentrations above established thresholds a Site Management Plan (SMP)will be prepared and implemented(as Kensington Assisted Living Facility Project 48 Initial Study Redwood City Apri12013