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6.R. - Page 6 of 9 <br />Community Development <br />Department Redwood <br />Engineering Division City I California <br />1 <br />1017 Middlefield Road Pouiwled1667 <br />Redwood City, CA 94063 / <br />Memo <br />(650) 780-7234 <br />planning@redwoodcity.org <br />www.redwoodcity.org <br />To: Steven Turner, Acting Community Development Director <br />From: James O'Connell, Senior Civil Engineer <br />Date: May 24, 2019 <br />Re: Establishment of Polychlorinated biphenyls (PCBs) in Priority Building Materials <br />Screening Assessment and Recommendations <br />PCBs are a major contaminant to the San Francisco Bay and the tributary creek systems. The <br />MRP regulates Polychlorinated biphenyls (PCBs) and other contaminants to minimize the <br />impacts to natural habitats including fish for human consumption. Urban stormwater runoff <br />is considered a significant pathway for PCBs into the Bay. Accordingly, regulatory agencies <br />are requiring that Bay Area municipalities address sources of PCBs in stormwater runoff <br />discharged to the Bay. This regulation targets selected building materials that may contain <br />relatively high levels of PCBs, especially in buildings constructed or remodeled from January <br />1, 1950 to December 31, 1980. During demolition, these building materials and associated <br />PCBs may be released to the environment and transported to the Bay by stormwater runoff. <br />The priority building materials are caulking, thermal/fiberglass insulation, adhesive/mastic, <br />and rubber window gaskets (BASMAA 2018).1 To identify these materials, an initial <br />literature review was conducted to identify the full list of known PCBs -containing building <br />materials and reported PCBs concentrations. The materials were then prioritized by <br />developing six factors that relate to the load or mass of PCBs associated with the materials, <br />the likelihood of the material to get into stormwater during the demolition process, and the <br />relative difficulty to remove the material from the building. A spreadsheet was used to assign <br />a score to each material based on the factors, which were evenly weighted. The materials <br />were then ranked and the highest scoring materials selected (LWA 2017).2 <br />1 BASMAA 2018. Protocol for Evaluating Priority PCBs—Containing Materials before Building Demolition. Prepared for Bay <br />Area Stormwater Management Agencies Association (BASMAA). August 2018. <br />2 Larry Walker Associates (LWA) 2017. PCBs Building Materials Prioritization, Excel Workbook. October 2017. <br />Page 1 of 4 <br />209 <br />