For the past six years, through low water and high, Geotechnology Inc. has been providing engineering support for the South Harbor project at America’s Central Port in Granite City.
With the help of two TIGER (Transportation Investment Generating Economic Recovery) grants, the port has been working to bolster the levee and bring in rail lines to service the South Harbor location. The project is important, according to the port’s executive director, Dennis Wilmsmeyer, because it opens the region up for both domestic and international freight shipping 12 months a year – regardless of river level. Currently the docks above Lock 27 are subject to closure due to both high and low water levels.
Luke Heuerman, manager of Geotechnology’s Illinois office, says there were underseepage problems to solve with the levee system at the South Harbor site. A combination of a cut-off wall and relief wells was designed to alleviate that issue. This cut-off wall is an excavated trench about 10 feet deep and backfilled with compacted clay. The trench extends through a surface sand layer down to an imperious clay layer, he explains. The purpose of the cut-off wall is to reduce the volume and seepage pressure of floodwater from the river working its way under the levee. Relief wells are well systems that penetrate through the sand below the clay layer to bedrock and are used to relieve the groundwater seepage pressure generated by river floodwater levels to prevent sand boils. Those two projects have been completed, Heuerman says.
Currently, Geotechnology is performing construction observation and quality control testing for the construction of the new slip harbor. A contractor has been hired to excavate the harbor and Geotechnology is observing the material coming out and performing soil tests both in the field and in its laboratory. The excavation contractor, a local road builder, will be using the materials for road beds.
They’re placing it in roadway areas, future building sites and parking pads and they need to make sure that it’s compacted properly to reduce settlement and provide a proper base for the road, Heuerman says. The sandy, silt material that comes out of the river can be used underneath roads and even buildings if done properly, he adds, noting that it’s not as easy to work with as normal soil because it is more susceptible to moisture content.
Harbor excavation will continue through the summer, according to Heuerman. The next step will be building the moorings for the barges and constructing a sheet pile wall along the northern bank of the harbor.
When the harbor is completed in the first quarter of 2014, it will bring together four interstate highways with rail and water transportation systems to link the agricultural and industrial producers of the heartland to the major cities of the world.
The Tri-Cities Area Port District board of directors and staff are focused on completing the project prior to the reopening of the expanded Panama Canal. That $5.2 billion project is expected to be completed in early 2015.