Last of Big Dam Repairs to Be Completed

Saja Hindi | Loveland Reporter-Herald

Crews are putting the finishing touches on repairs to the Nelson Big Dam and expect to have them completed in the next few weeks.

The masonry arch dam, built in 1895, is located west of Loveland’s water treatment plant, and was significantly damaged in the September 2013 flood.

The dam diverts raw water to the city’s water treatment plant, provides drinking water for the Johnstown water treatment plant, and irrigates about 20,000 acres of farmland in Larimer and Weld counties.

The Consolidated Home Supply Ditch and Reservoir Co. owns the 60-foot-plus dam, which didn’t suffer major damages in the 1976 flood, but the 2013 waters left a lot of damage.

The dam is also identified as a Colorado Historic Civil Engineering Landmark, so crews had to make sure not to change the historic aspects of the dam substantially. That included using stones from the same quarry as the original stones.

Crews are working on Phase II of repairs now, according to Home Supply board member Gary Gerrard, which encompass the pointing or refacing of the dam (grouting stones on the face of the dam), a need caused by years of erosion. Once that’s completed, he said, crews will close the gate.

The dam was operational April 1, 2014, in time for the spring runoff, and repairs continued while it was in use, aside from taking a break in the winter months.

City of Loveland senior civil engineer Larry Howard said after the flood the city used water from Green Glade Reservoir through the spring of 2014.

“The condition of the river was such that the water was unacceptable anyway,” Howard said.

And Howard said the dam is a “critical component” for the city’s water supply.

“It is the method by which we can get water directly from the Big Thompson River into the water treatment plant,” he said.

Some of the repairs after the flood damaged the dam, Gerrard said, included restoring the crest elevation, mitigating future flood effects by strengthening the dam with concrete abutments and installing a new spillway that configures water to go around instead of on top and updating to 21st century technology such as an automatic gate that fluctuates with river flow.

Because the flood damaged the dam’s main gate, the company was also able to replace other gates not damaged by the flood that were almost unusable and rusting because they were first put in 1915.

Funding for the repairs came from the city of Loveland, the Home Supply board, the Colorado Water Conservation board and the Federal Emergency Management Agency. The city committed to paying 50 percent of the costs not covered by federal and state grants. The conservation board committed to covering uncovered costs through long-term low-interest loans.

The total cost of repairs, Gerrard said, is about $3 million. Of that, $2.2 million is expected to be covered by federal aid.

Gerrard said the entities were able to keep costs low through “the methods of construction and the ability we had to be able to make decisions in the field, and the cooperation we had from all the entities to react to the things we found out in the field.”

Because officials could make decisions quickly, there weren’t a lot of construction holdups, he said.

Howard said city officials have been pleased in working with the Home Supply company.

“It’s been a very good partnership and successful project, and one that’s of critical importance to both of our entities,” he said.

Source: Loveland Reporter-Herald