SCOPE OF WORK – PROJECT DESCRIPTION

In August 2020, the city of Boulder, CO began the rehabilitation of the city’s Goose Creek Sanitary Sewer Interceptor system due to aging infrastructure concerns. In addition to the CIPP and open cut pipe rehabilitation, the project scope included the installation of 16 new 60-inch manholes and rehabilitation of 14 existing 48-inch manholes. A&W Coatings (A&W) was selected to coat all manhole structures with Warren Environmental’s (Warren) 301-14 high performance epoxy. 

 

Prior to coating the structures, the A&W crew stopped numerous leaks in the structures to be rehabbed by injecting Warren’s 151-HG hydrophobic grout product—a benefit of Warren’s diverse product line. 

 

For surface preparation, the new manholes were abrasive blasted and then washed to meet a concrete surface profile (CSP) level five blast profile, whereas the existing manholes were only water blasted due to their existing profile. A&W applied 125 mils to the new structures and 250 mils to the rehabbed structures via spray application. Additionally, A&W troweled Warren’s 301-14 mastic epoxy into 21 manhole joints to seal several manholes and create a smooth transition between sections. 

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PROJECT CHALLENGES AND SOLUTIONS

The project’s location and site layout presented challenges including roadway work, greenway work within a bike path, and protected local animal habitat areas. Several of the manholes coated were located within a busy roadway, requiring traffic control efforts that were provided by the general contractor. A large section of the scope of work was located in a public greenway space, including a highly trafficked bike path with manholes running adjacent to it. A&W led the effort in managing pedestrian traffic on the bike path while safely performing work to maintain the project schedule. The A&W crew kept the bike path open throughout the project’s entirety, minimizing disruptions to the local community. In addition, the A&W crew ensured no negative impacts to the protected native prairie dog colonies in the area due to Warren epoxy’s environmentally friendly nature.  

 

Working around the extensive, six million gallons per day (MGD) bypass pumping operation presented a notable challenge. The 301-14 product’s quick cure time and non-hazardous attributes provided the general contractor flexibility when coordinating A&W’s scope of work with other construction activities. Warren’s epoxy coating system allows for a rapid return to service, with an average cure time ranging between four to six hours. This enabled A&W to minimize the amount of bypass required, allowing the crew to line the remaining manholes while other construction activities were taking place.