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4. ENVIRONMENTAL ANALYSIS 4.6 AIR QUALrry These pieces of equipment account for 80 percent of the total DPM emissions from on-site _ equipment. By installing DPM filters only on this equipment,the total DPM emissions for operations reduce by 70 percent. Thus,the maximum annual average DPM concentration over a 70-year period would be 0.0475 gg/m3 and the maximum incremental carcinogenic risk is estimated to be 14 in a million. Implementation of ULSD and DPM filters on all on-site diesel equipment would reduce the carcinogenic risk to an estimated 7 cancers per million(below the threshold of 10 in a million). However,this may not be feasible and/or technically possible so it is determined that this impact is significant and unavoidable. Mitigation Measure 4.6.4: Limiting operation of the on-site equipment to between 6 am through 6 pm,without retrofitting non-road equipment engines,would result in a carcinogenic risk of 33 per million. By limiting the hours of operation(of all diesel equipment) and installing DPM filters on the excavators,on-site haul trucks,and front end loaders,the maximum incremental carcinogenic risk is estimated to be 10 in a million. — Significance after Mitigation: By limiting on-site equipment operations to between 6 am and 6 pm and installing DPM filters on the excavators, on-site haul trucks,and front end loaders,the impacts would be less-than-significant. Impact 4.65: Project Carbon Monoxide Impact. Traffic generated by the project would have the potential to affect CO concentrations along surface streets and near stagnation - points such as major highways and heavily traveled and congested roadways. This increase in traffic would not only add more vehicles on the road but the increased congestion would cause existing non-project traffic to travel at slower,less pollution-efficient speeds. This impact is potentially significant. Vehicular emissions were computed using the CARB's emission factor model,EMFAC2002. EMFAC is ARB's computer model to estimate past,present, and future on-road emissions of HC, CO,NOx,PM,and SO2. It is anticipated that the production rate at the plant will vary from 1.7 to 4.0 million tons per year. At these rates there will be approximately 437 to 613 loads per day (annual average) and approximately 699 to 981 loads per day(peak seasonal)generated from the quarry. The approximate distribution of the proposed truck traffic would be as follows: 1. North towards Stockton,70% 2. East towards Modesto, 15% 3. West towards the Bay Area, 10% _ 4. South towards Los Banos,5% The traffic analysis evaluated the following intersections and the effect of Project and cumulative impacts: 1. Blewett and Koster(now South Costa Ranch Road) RMC Pacific Vemalis Quarry Miring and Reclamation Project 4.6-26 ESA/203015 Administrative Draft ERR March 2004