Bull Lake Dam

Dewatering of Bull Lake Dam

Bull Lake Dam modifications consist of constructing a temporary cofferdam, excavation for a new spillway and stilling basin, and removal of the existing spillway. The owner of this project is the Bureau of Reclamation, Great Plains Division, and the General Contractor is Malcolm International.

For the excavation of the new spillway, a design-build dewatering system was required. Malcolm Drilling contracted GeoEngineers out of Redmond, WA, for not only the pre-bid design but also for the submitted eductor design. The design-build dewatering system consists of a combination of eductor wells and deep small-diameter wells that can be converted to either eductor wells or vacuum-assist wells at a later date. Dewatering maintenance is required 24/7 during the running of the dewatering system, which includes a 100 HP supply pump with dual header pipes: one 6-inch providing water to the wells and one 8-inch returning water to the pump. Malcolm Drilling installed all 96 wells using a sonic drill rig to ensure that air was not used for spoil extraction. Well depths ranged from 55 feet to 90 feet, depending on the location on the dam. Dewatering will pull and maintain a water level approximately 35 feet below static water levels.

Malcolm Drilling