The Los Angeles County Sheriff's Department is using a regional air-quality grant to accelerate the replacement of the nation's largest fleet of prisoner transport buses.

Last week, Los Angeles County issued purchase orders for eight Motor Coach Industry (MCI) buses, as the second phase of a plan to replace 37 of the 82 buses in the sheriff's fleet. MCI will deliver the purpose-build buses in June.

The sheriff added the first 16 buses to its fleet in July. The remaining 13 buses have been budgeted for the coming fiscal year.

Purchase orders for the second phase of eight buses were mailed out today, said Rick Teebay, fleet and transportation specialist with L.A. County's Internal Services Department.

The replacement buses were eligible for grants totaling almost $7 million of the $20 million needed to replace the 37 buses. The county acquired the grants from the South Coast Air Quality Management District under the Carl Moyer program. The new buses will significantly reduce emissions, Teebay said.

"If all 37 new buses were operating at the same time, all 37 new buses would emit less than half the nitrous oxides (NOx) and particulate matter (PM or soot) emissions from just one of the older buses," Teebay said.

The new buses are powered by clean-diesel engines with particulate filters and urea-based Diesel Exhaust Fluid (DEF). A separate DEF tank injects the fluid into the exhaust pipeline. Typically, the South Coast AQMD doesn't fund clean-diesel upgrades unless the vehicles are defined as emergency vehicles under the state's Vehicle Code 165.

The sheriff considered CNG and hybrid versions, before selecting the MCI buses, Teebay said.

Each new bus costs about $560,000. Of that, Moyer grants covered about $188,000 for each bus. Additional Moyer funding will be available beginning in March in Southern California. For more details, visit the Moyer page of the district's website.