2015-016 - The Bristol Street Widening Project

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ENVIRONMENTAL IMPACT REPORT ADDENDUM Bristol Street Widening Project Warner Ave to Saint Andrew Place (Phase IV) Construction Activities Grading and excavation and use of hazardous materials during construction would create potential sources of polluted discharge. The construction contractor is required to conform to the requirements of the Statewide NPDES Storm Water Permit. Pursuant to the CWA, in 2001, the State Water Quality Control Board (SWRCB) issued a statewide general NPDES Permit for stormwater discharges from construction sites ( NPDES No. CAS000002). Under this Statewide General Construction Activity permit, discharges of stormwater from construction sites with a disturbed area of one or more acres are required to either obtain individual NPDES permits for stormwater discharges or to be covered by the General Permit. In addition, best management practices (BMPs) specified in the Caltrans Storm Water Management Plan (SWMP) are also applicable. The construction contractor is required to conform to the requirements of the General NPDES Permit for Construction Activities and any subsequent General Permit in effect at the time of project construction. As part of the statewide NPDES permit, the construction contractor would be required to implement BMPs into their construction operations to reduce potential water quality impacts to the maximum extent practicable through preparation of a SWPPP. The General Permit contains requirements that BMPs must meet, including: Erosion Control Erosion control, also called stabilization, is the protection of the soil surface so that soil particles do not become detached by water or wind; and trapping soil particles that do become detached and are moved by water or wind. Non - Stormwater Management Non- stormwater management is the reduction or avoidance of discharges other than stonnwater, such as from cleaning of vehicles and equipment, and spills of hazardous materials and hazardous wastes. Non- stormwater management includes requirements for the use and storage of hazardous substances so as to avoid spills and minimizes pollution by cleaning spills that do occur. The SWPPP contains BMPs chosen for a project based on the specific activities that would be conducted as part of that project, and the amounts of stormwater and non - stormwater runoff that are anticipated. The 1990 Final EIS /EIR included a mitigation measure to control stormwater runoff associated with construction activities. Impacts would be less than significant and would be similar to those identified in the 1990 Final EIS/EIR. Moreover, the project would comply with the updated NPDES requirements, as described above. Operational Phase Operation of the proposed intersection has the potential to degrade water quality as a result of vehicular travel, including increases in such pollutants as oil, gasoline, grease, lead, and dust. Discharge from the proposed project to stormwater facilities would consist of non -point sources. Stormwater quality is generally affected by the length of time since the last rainfall, rainfall intensity, urban uses of the area, and the quantity of transported sediments. Typical urban water quality pollutants usually result from motor vehicle operations, oil and grease residue. The majority of pollutant loads are usually washed away during the first flush of the storm occurring after the dry season period. Due to the nature of the proposed project, generally occurring within an existing developed area, project impacts are not considered adverse. Consequently, impacts would be similar to those identified in the 1990 Final EIS /EIR. Mitigation Measures No new additional mitigation measures are required. ANA 305 -194 (PER 02) CSA (AUGUST 2014) 133867 YU 40