2019-090 - Adopting the Mitigated Negative Declaration

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*:/ : 11-1 h WA Health Risk SCAQMD currently does not require health risk assessments to be conducted for short-term emissions from construction equipment. Emissions from construction equipment primarily consist of diesel particulate matter (DPM). The Office of Environmental Health Hazard Assessment (OEHHA) adopted guidance for the preparation of health risk assessments in March 2015. OEHHA has developed a cancer risk factor and noncancer chronic reference exposure level for DPM, but these factors are based on continuous exposure over a 30-year time frame. No short-term acute exposure levels have been developed for DPM. SCAQMD currently does not require the evaluation of long-term excess cancer risk or chronic health impacts for a short-term project. The replacement parks would each be developed in approximately two and a half months. The relatively short duration when compared to a 30-year time frame would limit exposures to on -site and off site receptors. In addition, exhaust emissions from off road vehicles associated with overall projectrelatedconstruction activities would not exceed the screening- level LSTs. For these reasons, it is anticipated that construction emissions would not pose a threat to off site receptors near the replacement park sites, and projectrelated construction health impacts would be less than significant. Operation Localized Operation -Phase Impacts Land uses that have the potential to generate substantial stationary sources of emissions that would require a permit from SCAQMD include industrial land uses, such as chemical processing and warehousing operations where substantial truck idling could occur onsite. The proposed project does not fall within these categories of uses. Although the park sites would have occasional use of landscaping equipment for property maintenance which would generate area source emissions, on site emissions would not exceed SCAQMD LSTs. Thus, operational emissions would not exceed the California AAQS and project operation would not expose sensitive receptors to substantial pollutant concentrations. Therefore, impacts would be less than significant Carbon Monoxide Hotspots Areas of vehicle congestion have the potential to create pockets of CO called hot spots. These pockets have the potential to exceed the state one hour standard of 20 parts per million (ppm) or the eight hour standard of 9.0 ppm. Because CO is produced in greatest quantities from vehicle combustion and does not readily disperse into the atmosphere, adherence to AAQS is typically demonstrated through an analysis of localized CO concentrations. Hot spots are typically produced at intersections, where traffic congestion is highest because vehicles queue for longer periods and are subject to reduced speeds. The SoCAB has been designated as attainment under both the national and California AAQS for CO. Under existing and future vehicle emission rates, a project would have to increase traffic volumes at a single intersection by more than 44,000 vehicles per hour�m 24,000 vehicles per hour where vertical and/or horizontal mixing is substantially limited in order to generate a significant CO impact (BAAQMD 2017). The proposed project is anticipated to generate less than 2 daily trips from both the 6th Street Site and the Raitt Street Site combined, therefore, there would not be any discernable changes in current travel patterns. The project would not substantially increase CO hotspots at intersections in the vicinity, and impacts would be less than significant. 75C-82