Dredging

May 2016 Update

In May 2016 Lisa Nicholas of the City’s Planning, Building, Zoning, & Economic Development department presented an update on the dredging effort to Common Council’s Planning and Economic Development Committee. To watch the presentation click here (and if the link doesn’t work, head to ithacany.pegcentral.com and click on “05-11-16 Planning and Economic Development Committee Meeting”). The presentation starts 23 minutes into the video. A summary of the presentation follows:

Background

In 2012 the state allocated $13 million to restore the inlet ($2 million was also allocated to the city in 2008 for dredging Cascadilla Creek, which has not yet happened). The DEC is the lead on this project. Within the inlet also lies a navigation channel under the control of the state Canal Corporation, so they share some responsibility as well.

Additional history on the flood control channel can be found in this Ithaca Journal article.

Project Summary

The project will occur in 4 phases:

Phase 1 – Design and construction of the sediment management (dewatering) facility
Sediment management will be located in the southwest corner of the city near Walmart. The DEC has a draft design now and it’s currently going through environmental review. An optimistic estimate of when design and construction of the facility will be complete is end of 2017. $2 million has been spent on design. Construction is conservatively estimated to cost $4 million.

Phase 2 – Dredging
Sediment will be pumped by vacuum and piped to the dewatering facility. The plan is to go down 1.5 feet, but places may be identified where they have to go deeper. If the aforementioned optimistic schedule works out, dredging could begin in 2018. We don’t really know if the money left over after design and construction of the facility will be sufficient to complete the dredging (unlikely).

Phase 3 – Dewatering
Drying (dewatering) in the sediment management facility can take 2-4 years. The wet sediment is put in geotubes and water slowly seeps out.

Phase 4 – Storage of the dewatered sediment
The current plan is to spread the sediment onto the same plot of land that the dewatering facility will sit on. Apparently the city has resold sediment in the past for reuse, but nothing has been planned in that vein at this time.