366 Environmental habitat Restoration at Nankin Lake
A man-made lake created 100 years ago had filled significantly with sediment and was no longer providing the local habitat the resources it once had. The local branch of the EPA decided to deepen the lake as part of a restoration project to restore it and the habitation that existed before and also increase the overall capacity of the lake for handling severe storm events. WaterSolve was part of the team that completed this work and was responsible for dewatering the dredged lake sediment in geotextile tubes before being sent to a landfill.
DOWNLOAD PDF Applications & ProductsGeotextile Tube Containers, DewateringServicesTurnkey Project ManagementIndustryMarine DewateringLocationMichigan, USA
Onsite Water Release
Clear water release with sediment contained in geotextile tubes (clear water was returned to lake)
Nankin Lake Before Dredging
Nankin Lake During Dredging
Chemical Treatment
Representative samples of lake sediment were collected and tested by a WaterSolve technician in the facilities laboratory. Dewatering polymers were evaluated based on water release rate, water clarity, and flocculent appearance. In addition, dosing rate(s) were determined during bench-top dewatering experiments and recommendations provided to the general contractor during this phase of the program. Based on laboratory testing, Solve 7118 followed by Solve 9330 was determined to flocculate and dewater the residual most effectively compared to the other products. Water clarity and flocculent appearance were good to excellent when Solve 7118 followed by Solve 9330 was added to a sample.
Geotextile Bag sizing
Geotextile Tube Containers are manufactured from high strength polypropylene fabric and designed to allow effluent water to escape through the pores of the fabric while retaining the chemically conditioned solids. The estimated in-situ volume planned for removal was 35,000 yd3. Based on these given estimations and lab testing done by WaterSolve, geotextile tubes were set on a 3-acre laydown area in order to be filled for sediment removal.
The Result
Over the course of several months of dredging, 50+ Geotextile tubes filled three layers tall were deployed and filled with sediment in the 3-acre laydown area. WaterSolve technicians were on site for the duration of the dredging project and managed the chemical conditioning and geotextile tube dewatering operations. WaterSolve’s CCTS (Chemical Control and Tracking System) was installed for the project to automatically adjust chemical doses based on dredge flowrate and density measurements. CCTS operators were also able to use the data collected from the CCTS and provide our client with valuable production information for the project. After the total 35,000-CY of sediment was removed and contained in the geotextile tubes, the tubes were left on site for 2-3 weeks to further dry before they were excavated, and the dewatered sediment was hauled to a nearby landfill.
