After two years of construction to modernize Paso Robles’ 59-year-old sewage treatment plant, the city kick-started some of the operations last week in preparation for its grand opening this fall.
The new systems are designed to stop pollution of salts, nitrates and disinfection byproducts into the Salinas River, which have caused costly state fines for the city.
Sewer staff is now involved in a 30-day trial operation of the new system, making fixes where needed and refining the process, wastewater manager Matt Thompson said in an email to the City Council and staff.
"Startup of the new treatment process will allow us to demolish the rest of the old treatment process, build another secondary clarifier, and finish up the project this fall," Thompson said.
The modernization project includes a complete overhaul of the waste removal and filtering process, a new pumping station and the option to facilitate future production of recycled water, among other improvements. “The new process is now getting established and within a week or two the quality of water we put into the Salinas River will be much improved compared to the previous treatment process,” Thompson said.
In 2013, the city awarded a $36.4 million construction contract to Fresno-based W.M. Lyles Co. for the work on the plant, located on the northeast side of town.
The plant was built in 1954 and saw small expansions in 1972 and 1989.
Meanwhile, residents may notice a smell of wet grass coming from the sewer in the next couple of weeks, Thompson said, which he attributes to the natural decomposition of some material used in the old filters that have been replaced by new technologies.
“This odor should diminish fairly quickly (within a couple of weeks) as the trickling filters dry up,” Thompson said.
The smell is different from the odor of rotten eggs coming in recent weeks from Firestone Walker Brewery’s new tank-rinse ponds at the brewery’s site on the south end of town.