PCWS RICHLAND WTP INHIBITOR TRENCH

The Project consists of implementing chemical system upgrades, including the addition of orthophosphate to the treatment process at the Richland Creek Water Treatment Plant (WTP). To address the complex configuration of chemical junction boxes and issues with sodium hypochlorite off-gassing, the junction boxes from the chemical building to the static mixer vault and lines from the lime injection vault will be extended using hand digging or hydro-excavation. This will allow for the installation of new horizontal conduits, eliminating inefficient "ups-and-downs."

The existing sodium hypochlorite, lime, and fluoride conduits will be replaced with new conduits, while the old conduits will be repurposed as drainage lines for the junction boxes, routed to the existing above ground drainage (AGD) structure. The orthophosphate system will utilize the polymer room within the chemical building and be routed to the static mixer vault, where it will be injected alongside fluoride and sodium hypochlorite. The project includes the following:

•

Demolition on pavement to access carrier pipes in roadway.

•

Performing hand excavation to expose existing pipes.

•

Removing and replacing existing 1/2" SHP tubing as shown on the plans.

•

Installing new 1/2" SHP tubing as shown on the plans.

•

Installing new 3" carrier pipe as shown on the plans.

•

Modification of existing 3" carrier pipe for drainage.

•

Modification of existing junction boxes for drainage and cast-iron drain covers.

•

Perform wall penetration at the static mixer.

•

Removal and replacement of two (2) existing injection quills.

•

Perform one (1) new wet tap for injection quill.

•

Install one (1) new injection quill.

•

Replacement of removed pavement and curbing