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Section 4.0 – Environmental Setting and Discussion of Impacts <br /> <br /> <br />City of Redwood City 49 Initial Study/Mitigated Negative Declaration <br />Sandpiper Elementary School Facilities Expansion November 2016 <br />4.8 HAZARDS AND HAZARDOUS MATERIALS <br /> <br />The following discussion is based, in part, upon a Phase I Environmental Site Assessment and a <br />Hazardous Pipeline Memo that were prepared in September 2014 by Cornerstone Earth Group, and <br />an Asbestos Soil Analysis by Forensic Analytical Laboratories. The documents are included as <br />Appendix B, C, and D, respectively. <br /> <br />4.8.1 Existing Setting <br /> <br />4.8.1.1 Overview <br /> <br />Hazardous materials encompass a wide range of substances, some of which are naturally-occurring <br />and some of which are man-made. Examples include motor oil and fuel, metals (e.g., lead, mercury, <br />and arsenic), asbestos, pesticides, and herbicides. A substance may be considered hazardous if, due <br />to its chemical and/or physical properties, it poses a substantial hazard when it is improperly treated, <br />stored, transported, disposed, or released into the environment in the event of an accident. <br />Determining if such substances are present on or near project sites is important because exposure to <br />hazardous materials above regulatory thresholds can result in adverse health effects on humans, as <br />well as harm to plants and wildlife. <br /> <br />4.8.1.2 Historical Use <br /> <br />A review of available historical aerial photographs and documentation indicate that Sandpiper <br />Elementary School was historically part of the marshland adjacent to San Francisco Bay. Levees <br />were constructed in the general site vicinity by the early 1940s and a Press Wireless Radio Station <br />building was constructed on adjacent property to the south in approximately 1946. Salt evaporation <br />ponds operated in the general vicinity during the 1950s and 1960s. During the mid-1980s, the <br />adjacent radio station building was demolished and fill was placed on-site and in the general vicinity <br />to raise ground surface elevations. Residential neighborhoods were subsequently constructed on <br />adjacent and nearby properties. The site was developed with Sandpiper Elementary School in 1997. <br /> <br />4.8.1.3 Groundwater <br /> <br />Soil borings and cone penetration tests completed on the project site as part of the geotechnical <br />investigation encountered groundwater at depths ranging from 4.5 to seven feet below the ground <br />surface (bgs). The groundwater flow direction is expected to be variable and tidally influenced. <br /> <br />4.8.1.4 On-Site Sources of Contamination <br /> <br />Chemical Storage and Use <br /> <br />Based on a 2014 site reconnaissance by Cornerstone Earth Group, small quantities of cleaning <br />supplies, gasoline, and other potentially toxic substances are stored on the project site for use during <br />typical daily maintenance and upkeep operations at the project site. Two electrical transformers were <br />observed on the site. The transformers were on concrete pads and located within fenced areas. No <br />7.A. - Page 80