Water Sewer and Storm Improvements

The Oak Street drainage area was identified in an overall wastewater system evaluation as a priority for combined sewer separation to reduce overflows during heavy rain events.  In addition, the combined wastewater was directed to a pump station so the separation would allow for smaller, more efficient pumps to be installed at the pump station.

This area of St. Johnsbury is also served by 6” diameter unlined cast iron mains which are subject to tuberculation.  The combination of the tuberculation and size limited fire flows in this area to below those recommended by National Fire Protection Agency (NFPA).

To aid in the reduction of stormwater flows, Dufresne Group teamed with Stone Environmental through a grant secured by the Caledonia County Natural Resources Conservation District (CCNRCD) to incorporate green stormwater infrastructure into the project in the form of infiltration swales.  Testing completed by Stone Environmental identified areas suitable for infiltration of stormwater with overflows to the stormwater collection system and areas that had less suitable soils but could still allow some infiltration.  These areas had underdrain installed in the swales to collect water that is unable to infiltrate. 

Dufresne Group completed preliminary and final designs and construction services for the water, sewer and storm improvements project which was completed under budget and ahead of schedule.