PROJECT PROFILE:

Dredging and Dewatering

Delavan Lake is 2,072 acres, about 60 feet at its deepest, and is both fed and drained by Jackson Creek, a tributary of Turtle Creek. Over time, the inlet had become clogged with so much sediment that it lost about 56 percent of its natural storage capacity and became less effective at cleansing the water flowing into the lake. In May 2011, JND Thomas Company, Inc. (JND) was selected by the town committee of Delavan to be prime contractor for the dredging and dewatering project because of JND’ s water borne environmental and commercial remediation expertise and due to the stringent return water quality standards required in the Delavan Inlet project.

The project consisted of preparing a mechanical dewatering laydown area for processing lake sediment, hydraulically dredging approximately 45,000 instu cubic yards of materialfrom a 3,000-foot navigational channel to a maximum depth of 5 to 6 feet. All dredging operations were performed under direct supervision and in compliance with all local, state and federal regulatory agencies consistent with issued permits. The dewatering aspect of the project was located on the city fire station parking area directly behind the fire station structure within less than one acre of open space, and approximately 3,500 feet away from the dredging activities. JND mobilized and plumbed together four various above ground tanks, each performing a unique separation/dewatering function including the utilization of four continuous belt presses to produce an average of 600 cubic yards per day of dewatered sediment that was trucked to a nearby approved landfill site. All water used from the lake during the dewatering process was returned back to the lake under the 30 ml per liter permit requirement.

 

The work required coordination with local authorities and residents near the fire station and adjacent retirement housing complex and the ongoing maintenance of submerged pipeline within Delavan Lake as to not interfere with recreational boating or access to any of the lakes facilities or launching ramps.

 

Relevant Project Elements

• Hydraulic Maintenance Dredging at an Active Recreational Facility
• Preparation and Restoration of the Mechanical Dewatering  Area including all Utilities
• Mobilization and Demobilization of a Mobile Multi Component Dewatering Plant
• Continuous Operation of Multiple Engine Driven components within minimum “Noise”

        levels

• Return Water from Dewatering Operations Averaged 19ml per Liter