Pleasant Street Transmission Main Installation

BETA completed the design and construction oversight of approximately 3,000 feet of new 20-inch water transmission main to service the Route 9/Route 90 Economic Development Zone (EDZ) area.  The project’s purpose was to ensure that the EDZ has  adequate  domestic  and  fire  water  service  to  meet  existing  and  future  water demands.  Additionally, the project also provides system redundancy, since the EDZ is currently fed from a single 20” water main.

The project spanned two communities (Framingham, MA and Southborough, MA) and  had  a  multitude  of  stakeholders,  requiring  extensive  coordination  by  BETA. Stakeholders  included  Framingham  and  Southborough  Conservation  Commissions and  Public  Works  Depts., MassDOT  (state  roadway),  MADEP  (wetlands  /  water quality  certification),  MWRA  (project  located  near  Southborough  facility),  Mass. Dept. of Conservation and Recreation (DCR), Tennessee Gas Company, and Genzyme Corporation (project located near major R&D park).

Stony Brook Bridge/River Crossing:  BETA  determined  that  the  existing  bridge could not support the transmission main and associated construction activities, so proposed that the water main be constructed adjacent to the bridge.  To minimize the  environmental  impacts  associated  with  construction  at  the  river  crossing  and the  sensitivity  of  adjacent  wetlands,  while  also  crossing  two  high  pressure  gas transmission mains, the water main was successfully installed, utilizing the horizontal directional drill (HDD) method.

Culvert Replacement: In accordance with the MassDOT design standards, the new culvert was designed to convey flow from a 50-yr storm event.  Due to flow restrictions in the downstream infrastructure, the allowable flow through the new culvert could not exceed the maximum flow through the existing culvert, currently limited to a 2-yr storm event.  To limit the allowable flow, the culvert was outfitted with a restrictor plate with bottom elevation of the plate set at the water level associated with a 2-yr storm.

Project included:

• 2,200 LF of 20” DICL water main
• 700 LF  of  20”    fused  PVC  AWWA  C-905  pipe,  installed  by horizontal directional drilling (HDD)
• 100 LF 8” DICL water main (Town of Southborough, MA)
• Replacement of twin 3’x3’ stone culverts with a 3’x6’ precast concrete box culvert