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San Joaquin County Community Diesel Engine Emission Control Technologies Development Department _ full day or shift and are regenerated at the end of the day or shift with the vehicle or equipment shut off. A number of the smaller filters are removed and regenerated externally at a"regeneration station." Because they have control over their regeneration and are not dependent on the heat carried in the exhaust, active DPFs have a much broader range of application and a much lower probability of getting plugged than passive DPFs. One result _ of this is that emission control groups for active systems are most likely larger than those for passive filters,depending on the particular system. While actively regenerated traps do not generally increase NO2 emissions as passive DPFs may(unless they include catalysis), special attention needs to be given to active traps during regeneration. Spikes in emissions have been — observed to occur during regeneration,prompting European researchers involved with the VERT project to require emission measurements over the regeneration period(Mayer 2001). ARB's verification procedure incorporates the same requirement. Ash Filter technology has been identified by ARB staff as potentially generating a new waste stream. As discussed earlier, DPFs are designed to trap diesel PM to achieve a net decrease in PM emissions. The carbonaceous component of the PM captured by the filter,which is by far the majority,is burned off when the — filter regenerates. Any inorganic components are left behind as ash in the filter and accumulate over time. This ash must be cleaned from the filter periodically and properly disposed of _ Ash Production and Composition _ Ash that accumulates within a DPF is comprised of inorganic substances carred along in an engine's exhaust stream. The primary source of ash is the combustion of lubrication oil in the engine. The nature of the inorganic additives present in the oil,therefore, determines the composition of the majority of the ash in a DPF. Other sources of ash include material arising from engine wear(small — compared to oil ash)and any inorganic fuel additives that may be used. Not considering fuel additives,the rate of ash accumulation within a DPF is primarily a function of the rate at which an engine bums oil. Ash collected from a diesel engine using typical lubrication oil and no fuel additives is primarily composed of oxides of the following elements: calcium, zinc,phosphorus, silicon, sulfur, and iron. Zinc is the component of primary concern,because it can be considered a hazardous waste depending on its concentration. In Section 66261.24,Title 22, of the California Code of Regulations, identifies two threshold limits for zinc: 250 mg/l for the Soluble — Threshold Limit Concentration and 5,000 mg/kg for the Total Threshold Limit DeSilva Gates Quarry Project Draft Environmental Impact Report L.t As 05105.05