This paper describes how the concrete structure was designed and specified (concrete weight and tolerances) with allowances for the specific geotechnical and hydraulic conditions (water depth, concrete weight and freeboard, water level management in the trench, excavation depth and uplift of the impervious layer etc). The paper describes the behavior and provisions of the concrete structure on the gravel bed foundation, which was preferred to sand flow to minimize the risks of liquefaction as the area is moderately seismic.