Virginia Graziani

The Redwood Times

Garberville Sanitary District and its contractor, T & S Construction of Sacramento, broke ground Friday, Nov. 13, for its wastewater treatment plant improvement project.

Following a long and detailed application process, GSD has received an American Recovery and Reinvestment Act (ARRA) grant of $3 million, enabling the project to go forward. T & S, the lowest qualified bidder, completed contract documents with GSD and began preparations for work on Nov. 3.

The project involves expansion and alteration of the current wastewater treatment system, which consists of several ponds and wetlands on the east side of the South Fork Eel River across the Bear Creek Bridge.

A new primary treatment pond capable of holding 4.5 million gallons of sewage and wastewater will be constructed to the east of the current ponds. This extremely large pond will allow solids to slowly settle out, and the remaining liquid will flow by gravity to its discharge into the next series of ponds.

The four current treatment ponds will be consolidated into two ponds where the bacterial bioactive process, “good bugs killing bad bugs,” will occur. Vegetation will enhance the process by removing nitrogen-fixing bacteria.

One of the current wetlands will be replaced by a new pond to receive clear water discharged from the bioactive ponds. Here remaining vegetative material will settle out.

Next, the effluent will flow into a disinfectant chamber for secondary treatment. Instead of using hazardous gas, chlorine disinfectant will be safely made on site by ionization from rock salt. The salt will be placed in a chamber called a “reactor,” where it will be zapped with electricity to separate the chlorine molecules from the sodium. The waste sodium will be pumped back into the treatment process for eventual disposal.

Finally, the treated effluent will flow into infiltration galleries to perc through the soil.

GSD General Manager Mark Bryant stated that in the future, GSD hopes to add a tertiary treatment stage, which will create such safe and pure effluent that it can be used for irrigation.

Additionally, the current project includes replacement of the sewage collection system in the oldest part of town along Riverview Lane, Sunnybank Lane, and Sprowel Creek Road. Beneath these streets are clay pipes installed in the 1920s, Bryant said. During winter storms, street runoff infiltrates these old pipes, diminishing the plant's capacity to treat sewage and wastewater from homes and businesses.

Although the improvements will effectively double the retention time of wastewater processing, this does not mean that the capacity to treat sewage will double, Bryant explained. Many other factors affect the process.

As part of the project, a five-year study will be done to determine total capacity based on the quality of the effluent, as measured by Biological Oxygen Demand (BOD) and Total Suspended Solids, the primary standards for wastewater treatment efficiency.

Bryant praised the GSD board of directors for choosing to create a green, passive treatment process as far back as 2000. At that time, the first step in improving the system began with replacing the main pipelines from town to the plant. The new lines were designed entirely for gravity flow, requiring no use of electricity or fuel for pumping.

”This board feels they are stewards of the resource,” Bryant said.