What does the county do with its biosolids?
| Friday, Sep 03 2010 02:00 PM
Last Updated Friday, Sep 03 2010 02:00 PM
Q: A recent question asked about the local use of Los Angeles-area sludge. My question is: What is done with Kern County sludge? Is it processed and used locally or is it sent to another area?
-- R M Lewis
A: That's complicated, as there are several sanitation districts in Kern County and they all do things a little differently. But here's what is done by districts in and around Bakersfield:
* The county's Kern Sanitation Authority, which handles waste from about 50,000 people in unincorporated areas around the city of Bakersfield, treats its sewage sludge to the "exceptional quality" standard for biosolids, said Tom McCutcheon, KSA wastewater system manager.
There are different classifications of biosolids: "Exceptional Quality," Class A and Class B.
The U.S. Environmental Protection Agency defines Class A biosolids as containing no detectible levels of pathogens. It describes Class B biosolids as being treated but still containing detectible levels of pathogens. Exceptional quality biosolids have lower metals concentrations than Classes A or B biosolids but have the same pathogen levels as Class A biosolids, according to the California Department of Resources Recycling and Recovery.
The Kern Sanitation Authority's biosolids are so well-treated they're "dry as dirt" and sent to a composting facility in Kern County, McCutcheon said. The Kern Sanitation Authority generates a relatively small 300-400 dry tons of biosolids per year, he said.
* There's also the North of the River Sanitation District, which generally handles waste from Oildale, some parts of the northwest Bakersfield area and a few sections of the city of Bakersfield. It treats its sewage sludge to Class A standards and applies the biosolids to farmland adjacent to its treatment plant on the north side of Seventh Standard Road, roughly five miles west of Enos Lane, said Larue Griffin, assistant district manager.
That plant and farmland are in the city of Shafter, and so not subject to the ban on the land application of biosolids in unincorporated Kern, which is being challenged in the courts. North of the River produces about 800 dry tons of biosolids each year, Griffin said.
* The city of Bakersfield treats its sewage sludge to the Class B standard for biosolids and land applies it to more than 5,000 acres of city-owned farmland south and east of Bakersfield. That city practice also is not subject to the county ban.
Bakersfield generated 3,755 dry tons of biosolids in 2008, said Louis Sun, city wastewater manager.
