The septic smell at Pleasant Valley Road and Highway 20 should disappear by April due to the installation of biofiltration media, an odor control mechanism used successfully by many communities.
The noxious odor, a persistent problem at this intersection, comes from pipes installed in 2019 that carry wastewater from septic tanks to the Lake Wildwood Wastewater Treatment Plant. The culprit is hydrogen sulfide, a gas produced by bacteria in the wastewater stream.
“We see this as a big problem,” said Trisha Tillotson, director of the Nevada County Community Development Agency. “The problem is compounded by sitting at the traffic lights.”
The original odor control system in the problem area experienced component failures (oxygen generator, recirculation pump, oxygen sensors) that rendered the equipment ineffective. Next, the county launched a pilot program that added chemicals to inhibit the growth of the offending bacteria, but it did not produce the desired results in eliminating the odor.
District officials believe the new project and approach will finally provide a long-term solution to address the problem. County staff will install two vaults, one on either side of Highway 20, to house the biofilter media. Pipes then transport the contaminated air and drain it beneath the media in the vaults.