Norfork Dam - USACE

Norfork Dam, Recovery - Maintenance Bulkhead and Siphon

Baxter County, AR


The maintenance bulkhead consists of a structural steel bulkhead capable of traveling on a steel monorail that is mounted to the existing spillway piers. The 65 ton bulkhead will be used to temporarily seal an individual gate bay to allow the bay to be dewatered and maintenance work to be performed on the tainter gate.

The siphon consists of a 42" diameter steel pipe to be used to maintain a minimum stream flow in the Norfork River when the powerhouse is not generating. The work includes three 42" intake valves installed as deep as 130' underwater, a 48" square by 45' long penetration through the dam and discharge piping descending 140' to the training wall. A cone valve on the training wall will spray 185 cfs into the stilling basin below the dam.

Mobley Contractors role as the prime contractor included self preforming the monorail support and monorail installation, relocation of the existing fish hatchery platform, assembly and erection of the bulkhead, removal of the concrete plug cut through the dam and installation of the siphon pipe, supports, valves and platforms.

Major subcontractors included Koontz Electric for the electrical and instrumentation, Mainstream Commercial Divers for the underwater work, Bluegrass for coring and wire sawing the dam as well as subcontractors for survey, welding and painting. Mobley Contractors furnished a barge mounted crane to provide hoisting for our work and our subcontractors.   

This project received the American Society of Civil Engineers Arkansas Outstanding Engineering Design of the Year Award. 

Click on the following link to go to Garver's website to learn more about the Siphon:

Also, Garver has an article concerning the Rolling Bulkhead, Click the following:



Contact Us

952 Highway 287
P.O. Box 150
Morrilton, AR 72110

(501) 354-2510