In 1878, prospectors R.E. McBride and the Boon brothers started the mining camp of Whitepine in their search for silver ore. There were once two sawmills running in order to provide enough lumber for the town which, at one point in time, had three hotels, three saloons, five stores, two livery stables, and other buildings. Today, the camp is a ghost town filled with approximately 135,000 cubic yards of mine waste material with elevated lead levels. The site is located entirely on United States Forest Service (USFS) lands within the Tomichi Creek drainage area of the Gunnison National Forest, approximately 10 miles north of Sargents, Colorado.
USFS was in the process of rehabilitating the land and needed an economical, open-bottom bridge structure to cross the creek and rehabilitate the road, just before town and eight miles away from Highway 50. USFS relocated the Galena Creek Road so that it no longer passed through the contaminated mine tailings area or near the foundations of the Akron Mill. The relocation of the creek above the site provided safe, resource-sound access for the public and private landowners. Furthermore, design parameters for the new bridge structure required that it provide Aquatic Organism Passage past the site of the new road, adequate flow capability to prevent flooding further down White Pine Road, and the ability to dissuade beavers from building dams and using the structure as an abutment.
As the final solution at the remote site, a 19'-5" x 6'-11" Aluminum Box Culvert (ALBC), 51.75' in length, was selected to traverse Tomichi Creek. The ALBC was selected for its cost savings, and ease and speed of installation, with the lighter weight materials eliminating the need for heavy equipment during the installation. In addition, the versatility of the ALBC system allowed for the use of 13' long precast strip foundations keeping the weight of each piece to roughly 6,500 pounds each. Again, the lower weight meant that large cranes would not be needed on the remote site. Instead, the system was installed via excavator and manpower.
"In the past, USFS has had very good luck with MULTI-PLATE and box culverts due to the ability to install them without the need of large cranes, the reduced maintenance of the structure as opposed to traditional bridges, and the hydraulic capacity of the structure," stated Doug Marah, Transportation Engineer with USFS.
Due to the inherent lighter weight of the structure and the ability to use precast foundations, construction was able to occur in the late fall despite the site's remote location and the low temperatures at the high altitude. The precast foundations allowed work to continue well past the cutoff period of a cast-in-place solution. Installation went smoothly and quickly, while providing USFS with an economical and open-bottom, environmentally friendly solution.
"In the end, USFS specified the ALBC over other options for various reasons," concluded Marah. "Those reasons included: the ability to meet the low budget, the fall construction time frame, the inability to ship concrete to the remote site where concrete was a minimum of two hours away, and the easier installation."