LaSalle Canal MGP Sediment Remediation

Project Summary

LOCATION: LaSalle, Illinois
CLIENT(S): Ameren
SCOPE(S) PERFORMED: Dredging, Sediment Management, Over Water ISS, Capping, Hydrographic Surveying

White Lake Dock & Dredge was responsible for dredging more than 75,000 cubic yards of MGP-impacted sediments from the Illinois River. In addition to performing all dredging and capping work, White Lake Dock & Dredge was responsible for providing all marine support for the 71,000 cubic yard ISS operation – the first large-scale floating ISS operation of its kind in the country – to include ISS swell management and barge positioning. The dredging removed up to 20 feet of sediment and the ISS extended up to 24 feet below the sediment surface. Following the completion of dredging and ISS activities, White Lake Dock & Dredge installed a layer of organic cap materials over areas that had been disturbed along the shore and within the perimeter ISS area. Layer placement followed a tolerance of -.1’ to +.33’ in lifts less than 6” thick. All dredged materials were solidified with Portland Cement and disposed offsite.

Materials were mechanically dredged utilizing a customized Case 460 long reach excavator (equipped with RTK-GPS dredge guidance software and White Lake Dock & Dredge’s environmental dredge bucket). The dredging consisted of both swell management (the removal of overlying materials following the drilling of ISS columns) as well as the removal of existing contaminated materials. Materials primarily consisted of very soft, fine-grained silts. Dredging was conducted within a tolerance of +0” and -.33’. This dredging was made more challenging by the presence of high voltage overhead power lines requiring close coordination with the local utility.

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