Olsson Associates


Water Resources team puts Boulder Creek back on track after flood

Tuesday, February 11, 2014

Deb Ohlinger, PE, CFM, Water Resources

Colorado is still recovering from the extreme rainfall event that flooded our state in September 2013. One of the harder-hit communities was Boulder, which was slammed with up to 17 inches of rain between September 11 and September 15. Boulder Creek filled and overflowed, and the power of the rushing water broke down creek banks and created new, disruptive pathways that adversely affected the community well beyond the temporary presence of the floodwaters. Since then, Olsson has been working on two projects to help get Boulder Creek back to pre-flood conditions.

Boulder Creek Near 61st Street

During the September rains, flooding at a segment of Boulder Creek east of 61st Street shifted the water flow to the northeast, bypassing the diversion to Green Ditch. Green Ditch Company irrigates up to 600 acres of land, and water flow needed to be reestablished in the original channel so that Green Ditch Company could exercise its water right. Olsson designed a repair for the channel to divert flows back into the original channel while allowing high flows to continue in the direction of the natural breach, like they did before the storm. Plans are nearing final approval so that permitting and construction can be completed by March 30 and in time for the 2014 irrigation season.

Boulder Creek Near 95th Street

Boulder Creek near 95th Street (Copyright 2013 Google)In another segment of Boulder Creek, floodwaters pushed out of a tight meander bend, creating a new pathway that flooded over 95th Street in Boulder County and forced the road to be closed. A temporary fix was implemented in the immediate aftermath of the storm. However, as a condition of obtaining a permit to do the emergency work, the Army Corps of Engineers (COE) required a more permanent solution and restoration of the site.

Olsson helped the Urban Drainage and Flood Control District, the City of Boulder Open Space and Mountain Parks Department, and Boulder County design a restoration plan for the 95th Street area. Olsson has completed plans to reestablish the original meander bend, developed a split flow to use the emergency repair channel during high-flow events, and included channel protection to maintain the two channels. The emergency repair channel will help decrease the pressure on the reestablished meander bend to keep it in place during future high-flow events. The COE has approved the concept, and construction should begin by March.

Mother Nature created much havoc in these two areas and outright devastation in other areas of the state last September. Olsson is proud to help communities like Boulder deal with the impacts of the flooding. If you have any questions about how our Water Resources team can help your community, please contact Deb Ohlinger at 303.237.2072 orĀ dohlinger@olssonassociates.com.

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