Project of The Year 2016 Rehabilitation Runner Up: Eldorado Springs Canyon Pressure Pipe Rehabilitation

The project was precipitated by extreme flooding in Colorado in September 2013. FEMA was quick to act as many foothill communities and towns had suffered catastrophic loss, with property damages of more than $1 billion. Part of the rebuilding effort included repairs to water systems and sustainability improvements.

The South Boulder Creek Division project for the City of Lafayette entailed updates to various water structures destroyed during the flood, including roughly 1,200 lf of 12-in. pressure pipe rehabilitation. Extensive evaluation of the pipeline completed after flooding had shown that the 40-plus-year-old pipe was pitted with pinholes and would require repair or replacement.

General contractor EZ Excavation performed a variety of work along the pipeline, including the rebuilding of outlet works and modifying the sand structure in Eldorado Canyon State Park. The work by EZ provided rare access to the normally inaccessible line, presenting an opportunity for trenchless rehabilitation. Insituform’s glass-reinforced InsituMain CIPP product was selected to rehabilitate the water line.

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The steel raw water line, pressure-rated at 45 psi, runs parallel between South Boulder Creek and the side of a mountain. An elevated road, South Boulder Creek and adjacent walking trails at the foot of the slope are located inside the park near the project location. The existing water line runs under the trail at the far side of the canyon. Access is difficult because there is an approximate 30-ft vertical drop between the road and the pipe.

Installation was scheduled for December as the creek flow was low and could be diverted and contained within a 24-in. casing pipe. Additionally, most of the equipment had to be craned over the river from the road using heavy equipment. The Insituform crew working on the installation had a jobsite roughly the size of a standard hiking trail.

The project was divided into two roughly 600-ft shots. The first installation started upstream at a sand trap structure being rehabilitated by EZ. The access to the first shot required a temporary ramp to be built from the park access road down to South Boulder Creek. An intermediate pit was dug for the second CIPP installation. Inversion of the second shot was completed quickly due to the 75-ft slope, but careful attention had to be given as there were a number of 11 degree bends down the line. The CIPP portion of the project was completed in three days to the client’s satisfaction.

Why Project Is Outstanding

The flood of September 2013 came with a fury throughout the State of Colorado, causing $1 billion in property destruction and the loss of eight lives. In the aftermath, sustainability and rebuilding of potable water structures were of utmost importance. The structures in the river water source were washed out and barely intact after the flood. Merrick designed the outlet works and sand structure modification project, awarded to EZ Excavation. EZ then contracted with Insituform to rehabilitate the raw water line which takes water from the structures down into town as a part of the municipal raw water system.

More than a year was spent planning and strategizing with not only FEMA, but also the Department of Environmental Quality (DEQ), Corps of Engineers, Division of Parks and Wildlife, City of Louisville, Farmers Reservoir Irrigation Company, Denver Water and Eldorado Springs Water. While the project was awarded in March 2014, construction did not start until the second half of 2015 to meet the state’s request to have all four construction projects completed concurrently.

The steel water line was hand laid against the rocky walls of the canyon opposite the roadway in areas that were washed out. More than 40 years in age with a portion that had a 75-ft fall down the canyon, the project required Insituform to install a reinforced CIPP liner solution for pressure pipe and potable water pipe. This liner, the next generation of Insituform’s glass-reinforced InsituMain product, is unique in that it uses a new specialized glass material from Owens Corning. Patents are pending on the specialized design.

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Prior to construction, preparatory work performed by EZ included cutting a temporary roadway into the river for access to the structures and then carting equipment over to each structure via an excavator. Insituform also strung out hoses across the river using cabling systems.

Weather was also a challenge. When it finally came time for installation of the pressure CIPP in late December 2015, a massive snow storm brought snow and 10 degree temperatures throughout the canyon. The installation went on as planned, with the two shots installed over a three-day period.

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The combination of difficult project location, working with multiple government entities, contractors and engineers during the planning process, inclement weather and the use of a next generation pressure pipe solution all contributed to making the Eldorado Springs pressure pipe project award-worthy.

This story was compiled by the Trenchless Technology staff.