East St. Louis Deep Cutoff Wall Installation and Flood Mitigation Project

Client

USACE St. Louis District and Bauer Foundation Corp

Services Provided

Slurry wall construction logging; soil identification; instrumentation installation; preparation of as-built and final drawings; data management

A yellow Deere excavator sits on a construction site near a cable-stayed bridge. Piles of gravel, a dump truck, orange safety cones, and caution tape are also visible under a cloudy sky.

Location

East St. Louis, Illinois

Project Practice Areas

Coastal & Waterfront, Information Managment

Project Specifics

The United Sates Army Corps of Engineers (USACE), through Bauer Foundation Corp. (Bauer), is leading a slurry wall construction installation through a mainline Mississippi River levee in East St. Louis, Illinois. According to the USACE, without this deficiency-correction project, the levee is in danger of failing due to under-seepage or through-seepage during flood events. The deep wall construction is accomplished using a combination of clam shell and hydrocutter excavation. The wall panel construction extends up to 140 feet below the levee toe.

Geosyntec Scope of Services

Geosyntec was retained by Bauer Foundation to provide panel loggers for the test section and production phases of slurry-wall installation. Geosyntec is providing panel loggers for the test section and production phases of the slurry-wall installation, including logging the excavation for each bite of every panel. There are 260 panels with one to three bites of 10.5 feet width. The installation of each panel location is closely monitored by sophisticated rig-mounted geo-instruments.

Logging consists of soil identification for the full column, including levee fill material, overburden soils, foundation sands, and bedrock. Correctly identifying bedrock is crucial to the overall success of the project, because it drives the embedment of each panel into the sound underlying rock formation. Each panel location is manually sounded to verify bedrock key-in depth. Following excavation, Geosyntec observes the sounding and cleanout of each bite. The USACE works with Geosyntec staff at the site to appropriately identify installation depths.

Notable Accomplishments

The project specifications require as-built contract drawings (redline markups) and final drawings showing panel verticality and overlap details. These are generated automatically using a GIS tool that imports the data generated by the hydrocutter rig during excavation, estimates the position of the excavation at several elevations, and calculates several overlap metrics. The layout, as-built geometry, and overlaps are all rendered in plan and profile views and exported in PDF and CAD formats to meet the contract drawing requirements.

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