Stormwater May 2012 : Page 18

it over the wall to the river channel.” Working with Electric Pump, the city has developed a maintenance plan for the Flygt pumps. It includes periodic pump operations to drain the wet well, the operation of the generators on a monthly basis, and periodic inspection and maintenance by Electric Pump. “There’s an extensive network of berms and walls to protect the city from the 2008 ﬂ ood level plus one foot freeboard—a safety factor,” says Marsh. “There are more than before, and they’re higher.” The city built ﬂ ood control berms and walls in addition to the new pump stations to protect the 1st Avenue corri-dor. 1st Avenue was reconstructed from Clear Creek to south of 6th Street and has an improved storm sewer system. The reconstructed 1st Avenue Bridge over Clear Creek is higher and longer and allows ﬂ oodwater to pass without backing up. Overall project work continues into 2012. Flood protection along the CRANDIC railroad embankment in-cludes earthen berms and concrete and removable ﬂ oodwalls. The rail-road bridge over Clear Creek will be replaced. “Both the railroad bridge and 1st Avenue bridge replacements will re-duce the risk of ﬂ ooding upstream,” says Marsh. The ﬂ ood control and stormwater improvement study identiﬁ ed 42 storm sewer outfalls to the Iowa River, Clear Creek, and Biscuit Creek. These storm sewers all will have backﬂ ow protec-tion to prevent stormwater from back-ing up into the streets. The city also is focusing on increas-ing its amount of open space. “It’s for the aesthetics and the environmental bene-ﬁ ts,” says Marsh. “A lot of our green ini-tiatives area based on providing a more natural system for inﬁ ltration.” This includes green space along Clear Creek between Biscuit Creek and 1st Avenue, and The Iowa River Land-ing Wetland Park on the inside curve of the river. The park itself is larger than 5 acres and includes 4.76 acres of wet-lands, which provide water treatment, ﬂ ood storage, erosion control, wildlife habitat, and groundwater recharge. In addition to ﬂ ood protection walls and berms, walkways, trails, interpretive signage, and a comfort station, it will be planted with native vegetation. Most of the work on these projects will be completed in 2012. The Red River Valley The Red River Valley is not a valley at all; it’s the ﬂ oor of what was once Lake Agassiz, a glacial lake that once may have covered as much as 170,000 square miles. Because it’s ﬂ at and low, ﬂ oodwaters are usually widespread and shallow, but along the border between Moorhead, MN, and Fargo, ND, it nar-rows to just a few hundred feet wide. The Red River forms the boundary between Minnesota and North Dakota from its source near the southern bor-der of Minnesota. It ﬂ ows north and drains into Lake Winnipeg in Mani-toba, Canada. Water from Lake Win-nipeg ﬂ ows into the Nelson River and 18 May 2012 www.stormh2o.com

Stormwater May 2012 : Page 18

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