IAI provided geotextile tube dewatering and water treatment operations services for the Mill River Remediation Project (Fairfield, CT), and was additionally responsible for odor control during dredging operations. Work was performed over a three year period, from 2014 – 2016, with operations scheduled in dredging windows, to accommodate shellfish spawning and fish migration periods. The project involved removing about 36,000 cubic yards of lead-impacted sediment from the river, processing the dredged sediment and contact water, and final disposal of the dewatered sediment.

Treated water discharge diffuser, installation in river

Clarifier effluent weir

Multi media filters

Active dewatering of stacked geotextile tubes, during second year of operations

Polymer feed system

Water treatment operator performing process control tests on site

Active geotextile tube dewatering

Dewatering pad and sump, during dredging operations

Overview of site during construction, prior to the start of dredging

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Project Statistics

4,875 lineal feet of geotextile tubes utilized
36,000 cubic yards of lead-impacted, dredged sediment dewatered
101.5 million gallons of water treated
Four layers of geotextile tubes stacked over the dewatering pad

Dewatering & Water Treatment Systems: Design-Build-Operate

IAI designed, constructed and operated the geotextile tube dewatering and water treatment systems used to process the dredged material, as well as separate chemical feed systems for controlling dredge slurry odors and flocculating the dredge slurry prior to dewatering. The geotextile tube dewatering system received dredge flow of up to 1,600 gallons per minute, or gpm, (averaging 1,200 gpm), and the water treatment plant (WTP) was capable of processing up to 1,500 gpm of water.

The WTP consisted of inclined plate separators, multimedia pressure filters and bag filters, and incorporated a pH adjustment process to remove dissolved metals such as lead. Plant instrumentation included real-time pH, turbidity and temperature monitoring. Treated water was discharged to the river under an NPDES permit issued by Connecticut Department of Energy and Environment (CT DEEP).