An existing 3.0m diameter x 30.5m long Corrugated Steel Pipe (CSP) culvert had to be replaced due to sagging of the roof as well as perforated corrosion on the floor. GeoMetrix was retained as the structural engineering consultant for the CSP replacement design. GeoMetrix also carried out an independent design check of the gabion basket retaining wall used at the culvert inlet.
The existing corrugated steel bin wall system at the inlet was replaced with a stepped gravity retaining wall consisting of Maccaferri Rock-Filled Gabion baskets. A reinforced earth Nilex retaining wall system was originally considered during preliminary design; however, this option was ruled out due to the existing utility cables which would interfere with the geogrid reinforcing layers. The design check of the gabion retaining wall was performed by both manual calculations and GawacWin Engineering Software. Global slope stability was checked by using the program Slope/W to better evaluate the myriad of log spiral failure slope planes.