Rain gardens to improve Sand Creek’s quality

Nine rain gardens were installed in a Coon Rapids residential neighborhood this fall in an effort to improve the water quality of Sand Creek.

The Anoka Conservation District (ACD) and the Coon Creek Watershed District (CCWD), using both their own dollars and a state grant, implemented the project which cost a little under $60,000 plus design, oversight and promotion/administration costs of more than $17,000.

The Coon Rapids City Council, on the recommendation of its Sustainability Commission, agreed to inject $5,000 into the project.

The rain garden demonstration project was in an area of Coon Rapids bounded generally by Foley Boulevard on the east, 121st Avenue on the north, Redwood Street on the west and Northdale Boulevard on the south.

According to Kathy Berkness, ACD administrative assistant, the district completed a stormwater retrofit analysis of the Sand Creek subwatershed for the CCWD in 2009.

The analysis identified cost-effective stormwater measures to decrease stormwater volume, decrease pollution loads and increase infiltration to recharge groundwater, according to the ACD website.

As a result, nine curb-cut rain gardens were installed in a residential neighborhood within the Sand Creek catchment, Berkness said in an e-mail.

The analysis identified high priority for rain garden placement because they were in large drainage areas or were in close proximity to existing catch basins, the ACD website states.

Property owners at the high priority locations were contacted by ACD and asked to volunteer the boulevard area of their properties for the rain gardens, which were installed in October, according to the ACD website.

The rain garden planting was completed by the property owners with assistance from ACD.

“The rain gardens will reduce the degradation of Sand Creek by infiltrating storm-water runoff that would have otherwise drained untreated to the creek,” Berkness said.

Through the project, which was designed by Metro Landscape Restoration Program staff, 1,901 feet of live storage volume has been created and 27.82 acres of the watershed, treated, according to the conservation district website.

Long-term maintenance will be handled by the landowners under an agreement with the watershed district, Berkness wrote in the e-mail.

According to the ACD website, post-project monitoring “verified exceptional rain garden infiltration rates and proper pretreatment chamber function followingt storm events.”

Monitoring will continue during the 2013 growing season to ensure proper garden function and successful plant establishment, the website states.

Sand Creek is a tributary to Coon Creek and the Mississippi River and untreated storm water had been discharged directly into the creek.

Representatives from the ACD and CCWD had an information meeting for affected residents at Sand Creek Elementary School in mid-October 2011. It was well-attended.

Participating residents had three rain garden shapes and three planting plans from which to choose.

In their agreement with the ACD and CCWD, property owners have been asked to commit to maintain the garden for a 10-year period through periodic weeding, plant/mulch replacement as needed and cleaning out the pre-treatment chamber.

Peter Bodley is at peter.bodley@ecm-inc.com

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