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PROJECTS WINDY GAP By Greg Silkensen No more waitin g to exhale WINDY GAP PIPELINE REPAIRS COMPLETE The Subdistrict and Windy Gap Project participants exhaled a collective sigh of relief when crews completed work on the Windy Gap pipeline. "We think we've fixed everything that needed fixing," says District Senior Water Resources Engineer Jeff Drager. The work included pipeline repairs and installation of a monitoring and protection system. Photo byjeffDrager Located just below the conflu- ence of the Colorado and Fraser rivers, the Windy Gap Project includes a diversion dam and 445- acre -foot reservoir, a pumping Plant, and a 6.5 -mile pipeline to Lake Granby. First envisioned dur- ing the 1960s, the project was not completed until 1985. Most of the Windy Gap pipe- Crews line is a prestressed concrete pipe patch cleaned and consists of a concrete core with a special grout wrapped tightly with 1/4-inch diameter steel reinforced wire. The pipeline's structural integrity is dependent on the steel wire and subject to failure if the wire breaks. Concern with the Windy Gap pipeline first surfaced in 1997 when a pipeline owned by the Denver Water Department ruptured, flooding an area adjacent to Interstate 25. The pipe he Windy Gap Firming Project is in the process of adding four new participants, but the size of the reser- voir and what it costs may decrease. Project Manager Jeff Drager said Evans, Fort Lupton, Lafayette and Little Thompson Water District are in the process of joining the project. All have or are buying Windy Gap Project units. The participants recently lowered their requests for storage by 15,000 acre feet, to 95,000 from 110,000. The estimated cost is $220 million. The District staff and consultants, Drager said, have done a lot of com- puter modeling to determine how the project will operate under various sce- narios. "As you add storage, you add yield," Drager explained. "But at some point, was the same type used for the Windy Gap Project. A consultant hired to inspect and test the Windy Gap pipeline found sections with substandard and corroded steel wire. During 2000, Subdistrict staff, consultants and contrac- tors analyzed and repaired 17 of the pipeline's 1,700 18 -foot sections. In 2004, after more testing, a contractor and Subdis- trict staff rehabilitated 10 additional pipe sections and installed a cathodic protection system along the entire pipeline. Cathodic protection is designed to counteract pipeline cor- rosion caused by corrosive soils and wet /dry soil cycles. Anodes installed along the pipeline produce a low voltage current through the pipe's reinforced wires, preventing further corro- sion and extending the pipeline's life. As the anodes corrode they will be periodically replaced. Drager believes repairs have significantly reduced chances of a pipeline rupture similar to Denver Water's. And cathodic protection should drastically slow, if not eliminate, additional corrosion of the pipe's steel reinforcing wires. "If we have any future problems they should be small in nature," says Drager. He noted that Subdistrict directors and Windy Gap partici- pants approached the repair work conservatively, fixing nearly every pipe section exhibiting any sign of corrosion or weakness. In addition to cathodic protection, future pipeline monitor- ing and testing is scheduled at 5 -year intervals. the curve flattens out. The participants are trying to get as close to the break even point as possible. There's no point in paying for more storage if there isn't any more yield." A draft environmental impact state- ment on the project is expected later in 2005. The Chimney Hollow site, located just east of Carter Lake, now appears to be the best choice. Its aim is to firm the water available to the Windy Gap Project under existing rights and agree- ments. The Windy Gap Project, completed in 1985 on the West Slope, delivers water through the Colorado -Big Thompson Project system. The disadvantage: Dur- ing some wet years, space isn't avail- able within the C -BT facilities for Windy Gap water and during dry years, water is not available at Windy Gap. Participants have sought solutions since 1990. Four years ago, they asked the Subdistrict to pursue a firming proj- ect. Staff and consultants completed preliminary fieldwork and needs analy- ses and the firming project is now in the formal environmental review phase. Reclamation hosted public scoping meetings in 2003. Last year, the U.S. Army Corps of Engineers and Reclama- tion, along with their consultants, began their analysis. An 18 -24 month design process would begin as soon as a site is approved and permits issued. Then, plans would undergo a dam safety review. After that, the participants would solicit construction bids. Building a reservoir is expected to take another three to four years. APRIL 2005 WATERNEWS