City of Mound, Minnesota
The city has long had a goal of increasing fire safety and providing multiple routes to bring water to the Island Park neighborhood. Seizing an opportunity to connect two areas of the water distribution system, Bolton & Menk designed an HDPE pipe connection that would be horizontally directionally drilled (HDD) under Lake Minnetonka between two parks and provide the needed link in their system.
A study for the watermain loop occurred during the winter months so that geotechnical investigation could be completed from above the frozen lake, saving the expense of barge borne drilling equipment. Poor soils under the lake demanded multiple iterations and alignments be considered as well as multiple drilling locations. Ultimately, an efficient and short route was chosen and permitted.
Part of the plan was to stage the fused HDPE pipe on the frozen lake, but warmer than normal conditions made this impossible. Changes to the plan and additional traffic control kept the contractor working and local residents circulating until the difficult drill and pullback were successfully completed.