Marine Manitowoc Outfall

EXPANDING THE MARKET FOR CLEANWATER

The City of Manitowoc built a new water intake system to provide water to the city and to transport water to other municipalities over 40 miles away.  Durocher Marine installed 4,000 ft of subaqueous Pre-Stressed Concrete Cylinder Pipe as part of this new system.  

INSIDE THE PROJECT

Our contract started at the new Intake Structure.  This structure was 500 ft onshore.  This required excavating the trench and installing pipe to line and grade. To maintain the trench in the sandy beach area, we installed 2 cantilevered sheet pile walls allowing us access to the work area and a way to keep the trench open for installation.  This allowed our excavation and installation barge to float all the way into shore.  Once the pipeline in this area was installed, a land-based crane backfilled the trench and removed the sheet pile walls.  

The remaining portion of the pipeline was constructed in the open lake. All excavated materials were sidecast and laid on bottom.  Once the pipeline was installed and secured with aggregate bedding stone, the sidecast material was reused as backfill to fill in the trench.  All sidecast material was either used as backfill or was smoothed to maintain the bottom contours of the lake.  

A diffuser structure was installed at the end of the pipeline.  This structure consisted of twin 90-degree elbows with copper Johnson Screens.  These are compliant with EPA’s 316b regulation, which protects fish larva from passing in and out of the system.  

The project was completed on time.  

WHY IT MATTERS

The new plant allowed the City of Manitowoc to realize a revenue stream by selling the clean water to new utilities.