The Wastewater Treatment Plant is part of the City of Ripon’s Fleet Maintenance Facility.

That’s the new Corporate Yard planned for the undeveloped property on Doak Boulevard. Back in December, the Ripon City Council awarded Diede Construction, Inc. of Lodi to handle the work for the 12,500 square foot maintenance building and parking lot at a cost of $11.1 million.

Elected leaders approved a change order on the project at the March 14 meeting not to exceed $288,622 – paid via Sewer Capital Enterprise Fund – for improvements on the Wastewater Treatment Plant.

The plan calls for Diede Construction to raise the elevation of the existing berm at the disposal ponds in order to provide additional storage capacity.

During the recent wet weather, the City’s Wastewater Treatment Plant disposal pond experienced some capacity issues.

According to the council report by Associate Civil Engineer Christianna Giebb, the City’s consultant reviewed the available data, discovering the following:

·         The groundwater elevation was above the bottom of the ponds as a result of the hydraulic connection with the river, in turn, increasing the volume of water in the ponds and reducing the percolation rates.

·         The rainwater doubled the volume typically discharged into the ponds – this water needed to be disposed of via percolation.

·         Little could be done to increase the percolation rates at this point. The focus now was to increase the storage capacity and not allow overflow into an unpermitted area.

The Fleet Maintenance Facility Project, meanwhile, involved the removal of over 7,000 cubic yards of dirt from the site.

The initial plan called for the dirt to be hauled away by the contractor.

It was staff that requested the contractor to provide a change order in order to utilize this excess dirt from one project (Fleet Maintenance Facility Project) to complete improvements to the berm surrounding the disposal ponds while increasing the storage capacity.

The work here would consist of removing any rock or asphalt on the surface of the existing berm while scarifying the surface and preparing it for the added layers if dirt. Another layer of dirt would be added and compacted down to 90 percent relative compaction, replacing the sections with a rock base or asphalt.

Once completed, the storage capacity of the disposal ponds would be increased to help prevent an overflow during significant rain events, Giebb noted.