Project: Miscellaneous Relief Wells
Location: Scott County, MO
Project Background & Description
Seepage that occurs during flood conditions on the Mississippi River needs to be controlled to ensure that the levee system does not fail during a project flood event. The overall project included installing 29 relief wells, modifying existing drainage systems to accommodate additional seep water, placement of riprap at drainage confluences to prevent potential scour, and clearing vegetation from existing ditches.
Bloomsdale Excavating (BE) was contracted to construct an outlet drainage ditch to collect water and drain new relief well discharge. In summary BE excavated 30,000 cubic yards of collection ditch for new relief wells and constructed a seepage berm at the levee toe, as well as installing 100 feet of 36" outlet culvert for the ditch and placed 800 tons of grouted rip rap. The project was being built to eliminate ponding water due to underseepage on the landside of the levee toe. A significant challenge included the fact that the collection ditch was approximately 1 mile long and the fill area was in standing water. As such, fill material was used to push water to a low point for pumping across the levee. The existing soil was extremely wet, hindering excavation and fill placement so BE constructed the drainage ditch from downstream to upstream so the ditch could be used to help drain the work area during construction.
The collection ditch was constructed and seeded ahead of relief well construction, allowing the relief wells to be drilled without being affected by the underseepage water. The newly constructed ditch kept the project dry for the relief well contractor.