Olsson Associates

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Olsson helps ‘Top 10’ city reduce flooding hazards downtown

Wednesday, July 13, 2016

Edie Adams, Marketing

Louisville, 1881

Louisville, Colorado, once a mining community in the late 1800s, is a thriving suburb of Boulder. Several times in the past decade, Money magazine ranked Louisville in its top 10 places to live, and in 2009, Louisville was ranked number one. A significant portion of downtown Louisville is in a Federal Emergency Management Agency (FEMA) floodplain, which puts homes and businesses at risk and hinders development in this desirable place to live. The primary obstacle for conveyance of storm flows is a railroad embankment.

The Urban Drainage Flood Control District (UDFCD) retained Olsson Associates to design improvements to reduce the flooding in downtown Louisville, remove insurable structures from the 100-year floodplain, provide safe conveyance to the nearby Coal Creek, and protect the city’s wastewater treatment plant.

The project followed a phased approach. It started with detailed analysis of the storm drain system and development of the floodplain, followed by an expansion of the scope to include storm drain and open channel design, permitting and coordination, utility management, trail design, and construction phase services, including materials testing. After construction is finished, a Letter of Map Revision will be completed to revise the FEMA flood insurance rate map.

The overall project includes 1.3 miles of open channel with drop structures; three pedestrian bridges; 3,200 linear feet of storm drain; a box culvert crossing and utility work on Highway 42; and a 72-inch diameter boring under the Burlington Northern Santa Fe (BNSF) railroad. In addition to UDFCD, Boulder County and the cities of Lafayette and Louisville are also project sponsors/stakeholders. Along with having multiple project stakeholders, Olsson is working with seven subconsultants and numerous internal teams, which requires diligent coordination and communication to keep the project running smoothly.

Because of permitting timelines, the project design was phased and bid in two packages. Two contractors were selected and are working with limited and overlapping space and access. Additional project challenges include aggressive design and construction schedules to obtain funding through the State Revolving Fund. There were other challenges for this project such as scheduling around summertime public events in downtown Louisville, coordinating with and allowing for a developer’s water quality/detention basin that connects into the open channel, and permitting through multiple entities.  

After this $9.4 million project is finished in a couple of months, the city’s residents and business owners will be better protected from stormwater events, and further growth and development can occur in this thriving city.

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