St. Maries Slow Sand Filtration Water Treatment Plant

St. Maries, Idaho

PROJECT OVERVIEW

The third and final phase of a 7 million dollar water improvement project for the City of St. Maries included construction of a 3.4 million gallon per day slow sand water treatment facility.  The City of St. Maries Slow Sand Water Treatment Facility is supplied raw water, by gravity flow, through approximately 58,000 lineal feet of new 16-inch diameter transmission line from the Rochat Creek Dam Water Intake.

The slow sand water treatment plant (“WTP”) consists of a two-cell slow sand filtration plant, unchlorinated clearwell, chlorine mixing chamber and a 198,500 chlorine contact chamber. The 24,000 square foot filter beds were constructed of cast-in-place reinforced concrete slab and walls.  The filters, which are 50-ft wide by 240-ft long, were then covered with pre-cast concrete roof planks.

 

 

Leak testing filter bay 2 prior to roof installation.

Major earthwork on this ridge above St. Maries allowed a complete gravity flow system.