Blunn Dam

Project Focus

This $900,000 soil-cement project was part of the Blunn Dam Arvada Reservoir Enlargement Project in Arvada, Co. The existing dam was aging, showing distress and needed enlarging. IHC was a subcontractor on this project to Sema Construction of Englewood, Co. The work consisted of furnishing and placing approximately 21,000 cy of soil-cement for the spillway liner and the buried cutoff wall. The spillway consisted of an apron 3' (3 - 1' lifts) in depth and 7' (7 - 1' lifts) high spillway walls. The cutoff wall was 30'high and 340' in length.

The project was bid on September 14, 2004 and had to be complete by April 15. 2005. This required the soil-cement to be placed during the winter months in Denver, Co. The soil-cement work started in January of 2005. While the winter was relatively mild for Colorado, cold-weather protection was still required throughout the project.

Project Details

Construction & Innovation
Typically, soil-cement is mixed in a pug mill but IHC modified a Hagan ribbon mixer and successfully mixed a quality product in a non-traditional method. Access to the dam was difficult so the plant was located proximate to the site and trammed to the placement site by wheel loaders. This allowed IHC to haul in all types of winter weather conditions.

Placement was by a D-5 Cat dozer using GPS guided instruments. The soil-cement was off-loaded by the Cat wheel loaders and placed in front of the D-5 by a Cat 325 crawler backhoe. Compaction was achieved by a combination of a dual drum vibratory roller and a rubber tire roller. The vertical face of the soil-cement required a 1:1 ratio stepped face making compaction on the face very difficult. IHC engineered and fabricated a compacting plate attached to a skid steer loader to compact the sloped vertical face. The face compactor was designed so that the skid steer could travel longitudinally to the direction of placement so production would not be hampered by this operation. The vertical face achieved all density requirements, and was well within all dimension specifications and never affected the productivity of the project.

All soil-cement was well within the designed parameters. The contract called for a 56-day strength of 800 psi compressive. The average for the project was 975 psi with all tests within the minimum limits. Specifications called for a maximum dry density of 96% as determined by ASTM D558. An average density of 98.3% was achieved for the project. To accomplish this during winter conditions the aggregate stockpiles were covered and insulated, a boiler was provided to heat the mix water and the product was cured with a white membrane cure and covered with insulating blankets to protect the product from freezing conditions. IHC developed and executed an internal CQC program that included testing, inspection and thorough documentation to provide risk management and to assure quality.

Schedule & Complexity
The project was successfully completed within the contract timeframe. The precautions and innovation of IHC enabled a product that was highly susceptible to cold weather to be successfully placed during the winter months.

Public Relations
The City of Arvada was very pleased with the high quality workmanship attained in less than ideal weather conditions. They were able to re-fill their dam on schedule.