The Town of Delavan, Wisconsin, has introduced plans to clean the engineered basins at Mound Road to improve the capture of sediment and thereby improve the water quality in Delavan Lake.
According to the Town, the basins have not been dredged since 2007 and are not longer as efficient at capturing sediment.
The Town of Delavan retained Baxter & Woodman, Inc. (Baxter & Woodman) to outline a plan to either hydraulically or mechanically dredge the Mound Road basins.
There are three basins including the North, West and East basin. A fourth alternative was considered with the goal of staying within the Town of Delavan’s $750,000 initial capital budget.
The alternatives reviewed include the following:
- Alternative 1 – Hydraulic dredging by contractors with sediment transport to a new drying basin adjacent to the site, sediment bags, and land disposal of the dredged waste. This option is based on the previous Berrini & Associates report dated June 26, 2017;
- Alternative 2 – Hydraulic dredging by contractors with sediment transport to mobile trailer mounted treatment units for removal and thickening of the sediment waste;
- Alternative 3 – Bypass each basin utilizing earthen berms and cut channels to the other basin(s) to reroute the water flow, and allow the sediment to dry. The sediment will be disposed of in an approved site;
- Alternative 4 – Direct purchase dredging equipment by the Town of Delavan with operation and disposal of the sediment at an approved site. DLSD would provide the labor for the periodic dredging of the basins.
Capital costs for the various alternatives ranged from just over $1,000,000 to over $3,000,000. These costs are in the ballpark of what was expected.
Baxter & Woodman is recommending Alternative 4, whereby the Town of Delavan would direct purchase several pieces of dredging equipment and would enter into an agreement with the Delavan Lake Sanitary District (DLSD) to provide labor for dredging operations.