Drainage Systems and Engineering Measurement Devices, St. Johns Bayou Floodgate, Missouri
Abstract
St. Johns Bayou floodgate is a multiple-barrel drainage culvert in the levee along the Mississippi River at New Madrid, Missouri. It will prevent backwater from flooding the area drained by St. Johns Bayou. The structure consists of six 10- by 10-ft concrete culverts, an intake basin, a control tower, and a stilling basin. Foundation conditions, relatively high differential heads in both directions, and excavation of approach channels which exposed deep pervious sands, made necessary the installation of drainage blankets and relief wells at each end of the structure to intercept potentially dangerous underseepage.The drainage blankets under the intake and stilling basins consist of a two-layer filter of sand and gravel with perforated collector pipes. Most of the wells consist of 4-1/2-in. ID perforated, flush joint, VC pipe inside of 6-in. ID porous concrete pipe; the wells under the structure proper have 5-in. ID Everdur metal screen. Flap gates are installed on the outlets for the drainage systems to prevent backflow into the systems during reversal of head. Pumping tests on the wells indicated specific yields ranging from about 5 to 40 gpm. Piezometers have been installed to measure the hydraulic gradient beneath the structure and uplift pressures beneath the stilling basin. Differential heads to date have not been sufficiently high to test the structure or drainage systems. The structure is founded on alluvial sands, and has settled from 0 to 1.0 in. since the levee has been placed over it.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1956
- Accession Number
- ADA637570
Entities
People
- R. C. Sloan