Nov. 9, 2023

Crews Add Concrete Encasement to Carter Lake Pressure Conduit

To make water deliveries to and from the new Chimney Hollow Reservoir, crews are tying the new reservoir into the existing Colorado-Big Thompson (C-BT) Project infrastructure. General Contractor Barnard Construction is reinforcing the Carter Lake Pressure Conduit to improve the existing system. 

Carter Lake and its associated pressure conduit were constructed in the 1950s by the U.S. Bureau of Reclamation as part of the C-BT Project. Carter Lake has a storage capacity of approximately 112,000-acre-feet and is the second largest reservoir in the C-BT Project’s East Slope distribution system. Water stored there originates in the headwaters of the Colorado River and travels east through the Adams Tunnel and other C-BT Project infrastructure to Flatiron Reservoir. The water is then pumped through the 1.4-mile Carter Lake Pressure Conduit to Carter Lake. 

Conduit pipe as part of Carter Lake Pressure Conduit outage

During excavation for the conduit in the 1950s, Reclamation added a concrete liner around sections where the earth foundation was not quite structurally sound, though the liner was not added to the entire stretch of the conduit.  

Reclamation provided a three-month timeline to Barnard to complete the work. Crews are working in 40-foot sections to limit the conduit’s exposure to inclement weather. As they do so, mechanically stabilized earth walls are placed on both sides of the conduit to create a fixed support system. These walls are made of a plastic geogrid allowing for compacted earth material to be placed to stabilize the conduit. Then, a rebar and concrete encasement is added around the pipe for reinforcement.  

The outage began on Sept. 25 and is anticipated to be complete by Dec. 18.