Spent lime filter to improve water quality in Wakefield Lake

by Chris O’Brien, communications coordinator

If you’ve driven by the corner of Frost Avenue and Kennard Street in Maplewood recently, you may have seen excavators digging a giant hole in the ground. Believe it or not, this is all part of our plan to improve water quality a few blocks away on Wakefield Lake. A new spent lime filter is nearly complete, designed to intercept stormwater runoff, remove phosphorus and ultimately send cleaner water downstream.

See the construction process in this video from the City of Maplewood.

Small lake, big watershed

Wakefield LakeAt only 23 acres, Wakefield Lake is one of our smallest managed waters. Prior to intensive development in the area, the lake was clean, clear and a favorite swimming spot for local residents. Today, the lake is impaired for excess nutrients, and we are partnering with the City of Maplewood to help clean it up.

This spent lime filter is our most ambitious project to date in this area. Stormwater from a large portion of the 944-acre Wakefield Lake subwatershed is piped into a large underground chamber where it interacts with spent lime. The lime material is a repurposed byproduct of municipal drinking water treatment, and it binds to phosphorus in the stormwater. Water leaving the spent lime chamber should contain about 70 percent less dissolved phosphorus than before.

Construction is expected to wrap up this month, and when all is said and done, the only thing you’ll see at Frost and Kennard are a few manhole covers used for maintenance on the spent lime filter. And hopefully, you’ll soon see clearer water in Wakefield Lake.

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