Nevada County water district OKs nearly $20M contract to replace Combie Canal | TheUnion.com

Nevada County water district OKs nearly $20M contract to replace Combie Canal

The Combie Canal runs above the Bear River on a steep hillside.
Photo courtesy NID

The aging, leaking Combie Canal, a concrete flume located along a steep hillside above the Bear River, received the OK for a nearly $20 million replacement Wednesday.

The canal is a “critical piece of infrastructure” that serves two water treatment plants, Nevada Irrigation District staff say, with more than half of the district’s flows for deliveries made through the nearly 50-year-old system. The canal also serves as a secondary conduit for deliveries made through the Bear River Canal, including to 3,427 Placer County Water Agency customers in Lincoln.

On Wednesday, the district’s board of directors approved a $19.6 million contract for the long-planned Combie Phase I Canal replacement project. The canal, which is approximately 8,900 feet long, has limited access and has had ongoing leaks with three separate failures, Engineering Manager Gary King said.

History

In 2002, for example, the canal developed a gash, forcing irrigation water and hillside debris into the river to the point where the water ran brown.

It is at high risk of future failure due to hazardous upslope conditions (trees and rock fall) and sub-surface failures, due to water infiltration, King said.

The project has been in the works since at least 2012, when water district directors approved environmental studies to upgrade the canal, which begins below Combie Reservoir and then winds through the steep walls of the Bear River canyon.

At that time, the project was estimated to cost several million dollars.

In 2015, the water district began discussing a potential bond issue to finance the upgrade. Its engineers had placed a priority on its construction after the 2011 failure of the Bear River Canal, a similar facility operated by PG&E.

In 2016, the district began searching for contractors for both the canal replacement and an addition of an aerial siphon, which regulates the flow of the river. The siphon project was completed in July and is now in service. The remainder of the project will replace the existing concrete flume section with a single, 96-inch reinforced concrete pressure pipe, partially buried, along the entire length of the canal. Construction will occur over two fall/winter seasons when the flows are low enough to allow a bypass system to be installed, according to King’s report.

By the numbers

In December, the water district sent out quote documents and received three quotes that ranged from $19.6 million to $27.6 million. King noted in his staff report that construction of this project would be difficult due to the location, terrain and limited access.

Steve P. Rados, which bid $19.6 million, estimated a local business participation goal of 6.8 percent or $1.3 million, saying this is a specialized project with limited opportunities from both suppliers and contractors. Rados stated that it will continue to seek local businesses, use local businesses for operational costs such as fuel and miscellaneous supplies, and would solicit craft workers within district boundaries to construct the project.

Contact reporter Liz Kellar at 530-477-4236 or by email at lizk@theunion.com.


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