Dam fast - Design and construction of the Pajarito Canyon RCC Dam

In 1999, fire swept the national forest and areas surrounding the city of Los Alamos New Mexico and the Los Alamos National Laboratory. Over 40,000 acres of forest and adjacent lands were burned. The threat from fire soon turned to threat from flood as previously vegetated lands were determined to be unable to control surface runoff of rain. The Department of Energy, utilizing the Albuquerque District Corps of Engineers launched an emergency effort to address this problem.

Los Alamos is a high elevation town situation on several parallel canyons. Emergency efforts addressed flood protection issues on each of the critical canyons. Flood protection measures for one of the canyons, Pajarito Canyon, were necessary to protect against the consequences of flooding to a nuclear testing facility and a downstream community. The magnitude of the estimated flows required a structure of dam proportions.

With only a few months of time to construct appropriate structures, a staff of personnel from the Corps of Engineers, a private engineering firm, and a construction firm were assembled in Los Alamos, New Mexico. These individuals collectively designed and constructed a major dam project in unprecedented timeframe.

With the scope of the Pajarito Canyon project evolving, site selection, foundation exploration and foundation excavation began on 2 July 2000. Design of the structure commenced on 5 July. Mobilization of equipment, setup of the plant, stockpile of materials progressed concurrently with the design of the 120-foot high RCC dam and overflow spillway. RCC construction began on 22 July. The 70,000 cubic yard RCC structure was complete by the end of August. Construction of the conventional concrete overflow structures, the intake tower, final excavation was done during the following 2 months.

The presentation will provide a summary of the design and construction activities as well as problems encountered. 10 pp.