In September of 2013, the Boulder County experienced a 500 year flood event causing millions of dollars’ worth of damage to infrastructure throughout the County. In response to this flood damage, the County awarded AWC a creek stabilization and rehabilitation services contract. Funded in part by the U.S. Department of Agriculture’s National Resource Conservation Service (NRCS), the County selected AWC to repair two severely damaged stream/creek sites in the county.
The first site, Streamcrest, consisted of the reconstruction of the stream channel to its pre-flood alignment and removing debris and sediment from approximately 2,100 feet of Left Hand Creek. The work involved controlling active stream flows during the initial spring snow melt, excavation and export of 20,000 CY of sediment, 3.5 acres of seeding and mulching, 400 CY of riprap, 500 CY of earthfill for a diversion structure, and 1,300 CY of clearing. The work begin within one week of notice of award, and AWC worked 12 hours shifts, 6 days a week to complete the work prior to the peak spring run-off.
The second site, Raymond-Riverside, consisted of stream rehabilitation at five specific sites in the Middle St. Vrain Creek in Raymond, CO. The work involved protecting and rehabilitating creek banks washed out by the floods. Specifically, the work included a house demolition, 850 CY of debris removal, 2,600 CY of channel excavation, 1,200 CY of riprap placement, and construction of a 1,500 SF precast concrete block retaining wall. This site proved particularly challenging due to the narrow canyon in which the creek flows. The majority of this work was accomplished in the creek without the benefit of a creek diversion.