Spent Lime Treatment System for Wakefield Lake

Project Details by Fiscal Year
2016 Fiscal Year Funding Amount
Fund Source
Clean Water Fund
Ramsey-Washington Metro WD
Recipient Type
Local/Regional Government
Start Date
January 2016
End Date
December 2018
Activity Type
Counties Affected
Project Overview

Wakefield Lake is in the Ramsey-Washington Metro Watershed District (RWMWD) and is impaired for excess phosphorus. Through the Wakefield Lake TMDL process, implementation activities have been identified which include partnerships with the City of Maplewood to install BMPs in the watershed to directly benefit Wakefield Lake. RWMWD has researched, monitored and field tested the use of spent lime for stormwater quality treatment. Spent lime consists of calcium and carbonate and is a byproduct of the drinking water treatment process that has properties that allow it to bind with dissolved phosphorus. When water containing dissolved phosphorus contacts the lime material, calcium from the lime binds with the phosphorus and forms calcium phosphate which is a solid material and does not dissolve in the storm water, thus remaining within the treatment system. Although this is still an emerging concept, three years of monitoring a test spent lime system has shown promising results for the removal of both total and dissolved phosphorus. Total phosphorus removal through the system is approximately 60% and total dissolved phosphorus removal is approximately 70%. With the help of this grant source, RWMWD hopes to install a full scale spent lime filtration system on a City of Maplewood owned lot just upstream of Wakefield Lake at the southwest corner of Frost Avenue and Kennard Street to treat stormwater flow before it reaches the lake. This treatment system will achieve nearly 50% of the needed phosphorus external load reductions to Wakefield Lake as identified in the TMDL. This is great news not only for the very popular Wakefield Lake and the visitors to the adjacent park system but also to its big brother, Lake Phalen, to which Wakefield Lake drains before it heads to the Mississippi River.

Competitive Grant Making Body
Advisory Group Members and Qualifications
Conflict of Interest Disclosed
Conflict of Interest Contact

Nicole Clapp

Legal Citation / Subdivision
Laws of MN 2015 1st Special Session Chapter 2, Article 2, Section 7
Appropriation Language

Projects and Practices 2016: Laws of MN 2015 First Special Session Chapter 2, Article 7, Section 7

2016 Fiscal Year Funding Amount
Other Funds Leveraged
Direct expenses
Number of full time equivalents funded
Proposed Measurable Outcome(s)

Stearns County Pollutant Loading Model

Measurable Outcome(s)

This project resulted in an estimated annual reduction of 18.2 lbs of phosphorus and 2.384 tons of sediment.

Proposed Outcomes Achieved
Achieved proposed outcomes
Source of Additional Funds


Recipient Board Members
Board information for grantees can be found within contact directories on BWSR's website under Operational Resources, "About Our Partners".
Project Manager
First Name
Last Name
Organization Name
Ramsey-Washington Metro WD
Administered By
Administered by

520 Lafayette Road North
St. Paul, MN 55155

651- 296-3767