Sanitation plant failures threaten groundwater
November 26, 2012
During an inspection of the South San Luis Obispo County Sanitation plant earlier this year, federal Environmental Control Agency (EPA) inspectors discovered several self-monitoring and biosolid handling deficiencies that could result in groundwater contamination, according to a recently released compliance evaluation inspection report.
Of greatest concern to regulators is the practice at the plant of pouring biosolids, which remain after sewage treatment, from separating equipment onto the ground. The sewage residue is then transferred for storage on porous soil near the Arroyo Grande Creek Levee.
“Biosolids are stored on porous soil surfaces, and have the potential to contaminate groundwater,” the report says. “The discharger was not storing the biosolids processed by the centrifuge on the engineered drying beds, as stated in the permit.”
In response to the unsatisfactory evaluation, plant representatives told officials from the EPA and the Regional Water Quality Control Board they plan to pave the biosolid storage area, “but no timeline has been set,” according to the report.
In addition, inspectors found that employees at the plant have not been performing self-monitoring procedures in a manner required by the plant’s permit. Representatives from the plant told inspectors they were not aware of the testing requirement, “but now that they understood it,” they would start complying, the report says.
Meanwhile, management at the aging plant is under fire for three releases of improperly treated sewage into the Pacific Ocean during the past four months. Under its permit, a release of more than 200 MPN (most probable number of fecal coliform per ml) is a violation and inline for mandatory penalties. The recent releases tested from 30,000 MPN to 160,000 MPN.
The sanitation district serves approximately 38,000 customers from the cities of Grover Beach and Arroyo Grande and the community of Oceano.