St. Cloud Spent Lime Filtration Project
The City of St. Cloud draws raw water out of the Mississippi River for their drinking water supply. The quality of raw water they take in seasonally fluctuates. Spring runoff and large rainfall events are the biggest contributors to poor raw water quality. Sediments, organics, and other contaminants get washed off the landscape and into our drainage systems, especially in urban areas. The City is looking to minimize these fluctuations by installing a series of up to nine BMPs to treat 935 acres of untreated urban stormwater. The proposed spent lime filter and pretreatment structures will capture organics and annually remove 145 lbs. of Total Phosphorus (64%) and 53.5 tons of Total Suspended Solids (88%) for the project area .
The 935-acre project area is divided into two subcatchments. One is 135-acres and discharges into the Mississippi River about 900 feet up gradient, and on the same side of the river as the City's intake pipe. The second area contains about 800-acres of untreated urban drainage that discharges just downstream of the intake but is within the same pool of raw water. The Tenth Street Dam by St. Cloud State University makes up the river pool in which the City draws their water. By targeting these subcatchments, the City can help protect their drinking water source from sediment and excess nutrients, two of the most concerning pollutants identified in the St. Cloud Source Water Protection plan.
The proposed BMPs will include pretreatment structures with energy dissipation to capture sediment and organic materials. The treatment train will conclude with a spent lime filter system. The spent lime filter will be located just upstream of the storm sewer outfall and will capture dissolved phosphorus from the stormwater before entering the Mississippi River. The spent lime filter media will be supplied by the City's Drinking Water Treatment Facility because spent lime is a waste product generated by treating raw water.
Marcey Westrick
[Projects and Practices Drinking Water 2020] (b) $16,000,000 the first year and $16,000,000 the second year are for grants to local government units to protect and restore surface water and drinking water; to keep water on the land; to protect, enhance, and restore water quality in lakes, rivers, and streams; and to protect groundwater and drinking water, including feedlot water quality and subsurface sewage treatment system projects and stream bank, stream channel, shoreline restoration, and ravine stabilization projects. The projects must use practices demonstrated to be effective, be of long-lasting public benefit, include a match, and be consistent with total maximum daily load (TMDL) implementation plans, watershed restoration and protection strategies (WRAPS), or local water management plans or their equivalents. A portion of this money may be used to seek administrative efficiencies through shared resources by multiple local governmental units. Up to 20 percent of this appropriation is available for land-treatment projects and practices that benefit drinking water.
The proposed spent lime filter & pretreatment structures will reduce the total organic carbon load and annually remove 145 lbs. of Total Phosphorus (64%) and 53.5 tons of Total Suspended Solids (88%) for the project area .
LOCAL LEVERAGED FUNDS