CLARENCE CANNON NATIONAL WILDLIFE REFUGE HABITAT REHABILITATION AND ENHANCEMENT PROJECT STAGE 5 GRAVITY DRAIN DEBRIS BARRIER SYSTEM

USACE St. Louis District is seeking businesses that can provide a debris barrier system at Clarence Cannon National Wildlife Refuge (CCNWR) gravity drain in Annada, Missouri. The gravity drain is along the southern exterior berm of the refuge along Bryant?s Creek. The gravity drain is a concrete structure with a 16 ft wide and 18 ft tall opening. The structure allows water to flow in and out of the refuge by operating an overshot gate.

A bridge deck lays over the gravity drain to allow vehicular access along the berm. The bridge was designed to resist AASHTO HL-93 tandem and lane loads.The project consists of designing and installing a debris barrier system to the existing gravity drain structure that can be raised when operating the gate. The barrier must be removed during the event of water overtopping. The barrier must prevent woody debris from entering the gravity drain. The woody debris ranges from 1 in. to 6 in. in diameter.

A maximum of two workers is desirable to operate and maintain the system. There are no power sources onsite and no permanent power sources are anticipated. The gravity drain holds approximately 4 feet of water when the gate is closed.The proposed design must follow USACE guidance and standards.The following figure shows the overshot gate at the gravity drain. The photo was taken from the refuge side during construction.