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HL stormwater retrofit assessment
Jan. 10, 2011
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By Jennifer Kotila
Staff Writer

HOWARD LAKE, MN – Wright Soil and Water Conservation District (Wright SWCD) presented its stormwater retrofit assessment to the Howard Lake City Council at Tuesday’s meeting.

The assessment identifies areas within Howard Lake which can be improved using best management practices (BMP) to catch stormwater runoff and filter it before it runs into Howard Lake.

“Howard Lake was placed on the Minnesota Pollution Control Agency’s impaired waters list in 2008. Dutch Lake is proposed to be on the 2010 impaired waters list,” said Brian Sanoski, urban specialist for Wright SWCD.

Catching the stormwater runoff and filtering it before it reaches the lake will improve the quality of the water in the lake.

Areas of concern for the Howard Lake watershed are the total phosphorus, which is the amount of phosphorous carried in the water; and total suspended solids, which is the sediment load carried in the water; and the volume of water runoff.

“This is a good time to implement recommendations with the upcoming stormwater project,” Howard Lake City Engineer Barry Glienke said, referring to a major capital improvement project starting the summer of 2011 for its streets and stormwater sewers,.

The timing of the assessment and stormwater sewer project also places Howard Lake a few steps ahead of other communities in trying to control pollutants, according to City Administrator Kelly Hinnenkamp.

Sanoski noted the state will soon be mandating minimum phosphorus loads for lakes, so it’s good to have a head start in lowering the phosphorous levels going into the lake before the state mandates are in place.

The assessment and implementation of some of the recommendations are only the first stage in what will be a 10- to 15-year plan to repair the impaired waters of Howard Lake.

“It took years for the lake to get where it is today; it will take years to restore it,” said Shawn Tracey, landscape restoration specialist at the Association of Metropolitan Soil and Water Conservation Districts.

The assessment

Thirty-one catchments, or areas that collect stormwater run-off, were studied throughout Howard Lake to analyze each catchment’s existing annual pollutant loading and stormwater retrofit potential.

For each catchment, stormwater retrofit options were compared using specific site constraints and characteristics.

After analysis and comparison, nine catchments showing the greatest need, or that would be most appropriate to receive additional retrofits, were identified.

By weighing the cost, ease of installation, maintenance, and ability to serve multiple functions, those nine catchments were modeled at various levels of treatment efficiencies.

“We are recommending the most cost-efficient, cost-effective areas to address stormwater for Howard Lake,” Tracey said. “Many of the things identified will work well with the upcoming project.”

Recommendations

Most of the nine catchments analyzed are recommended for bioretention, or rainwater gardens.

Bioretention uses native soil, soil microbes, and plant processes to treat, evapotranspirate, and infiltrate stormwater runoff.

Basically, it means adding curb cuts above catch basins for the first flush of rainwater to flow into the catch basin, rather than into the storm sewer, with soil, gardens, and landscaping that will hold the water and filter it.

Bioretention requires private property owners in the city to agree to help in the maintenance of the landscaping and gardens that would be placed in their yards.

The next step in the process will be for Hinnenkamp, Glienke, and Wright SWCD to start planning.

To do this, they will be talking to private property owners to find who is interested in cooperating with the city on the project.

“We have to move kind of quickly. Barry needs to finish the design for the stormwater project, and there are funding timelines that need to be met,” Hinnenkamp said.

The water and sewer project is still in the planning stage. Plans should be complete by the end of March in order to obtain funding for the project.

Council member Pete Zimmerman questioned how this was going to work.

Wright SWCD will provide plans for where retrofits will work best for stormwater in the design Glienke is putting together for the stormwater project, and help educate private property owners about why the retrofits are needed.

The infrastructure for the retrofitting will be built with the project. The bioretention will be added a year after the stormwater sewer project is completed, according to Glienke.

Hinnenkamp pointed out the project has flexibility. The city can place the recommended retrofits with private property owners who are interested in them.

Odds and ends

In other business, the council:

• approved an amendment to the subordinate loan agreement and subordinate multifamily housing revenue note, extending the note from 2017 to 2024, and discounting the company fee by $1,000 for each year, 2010 to 2014.

• approved the grant agreement with Live Wright for the statewide health improvement project (SHIP).

• approved the 2011 fee schedule.

• approved sewer and water rates for 2011, with a 3 percent increase for the base rate and volume charge.

The water base rate is $21.70, with a volume charge of $3.44.

The sewer base rate is $21.71, with a volume charge of $5.81.

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