Hultman Aquaduct Interconnections

 
Location: Weston, Framingham & Marlborough Massachusetts
Contract Value: $47,542,388
Project Dates: August 2009 – August 2013

 

Project Summary:

The Hultman Aqueduct Interconnections project involves inspection support, rehabilitation, internal repair and new construction of over 13 miles of the MWRA’s 138” diameter Hultman Aqueduct.  Major items of work include:

• Construction of new buried valve chambers (120” diameter butterfly valves and associated steel piping) interconnecting the MWRA’s Metro West Water Supply Tunnel with the Hultman Aqueduct including new electrical, security, instrumentation and HVAC systems.
• Installation of new Triple Eccentric Design Butterfly Valves (48” & 60” diameters).
• Multiple dewatering and bypass pumping operations in order to support the pipeline inspection and repair operations.
• Pressure and leakage testing, disinfection, dechlorination, and flushing of the completed and rehabilitated Hultman Aqueduct.
• Installation of five new pressure reducing valves in the City of Waltham’s distribution system, including new precast vaults and restoration work.
• Multiple excavation sites throughout the project, totaling over 50,000 CY of material to be managed.

Dewatering / By-pass Pumping
Approximately 13 miles of 138” I.D. pipeline (over 57 million gallons) was dewatered in order to inspect and repair the interior of the piping system.  Due to existing valves continuously leaking into the pipeline, constant bypass pumping operations were employed, typically involving multiple 6” diesel powered pumps.
Over 80 existing culverts spread out along the 14 miles of pipeline had to be thoroughly cleaned out and repaired where necessary, which necessitated substantial control and diversion of rivers and ponds.  Multiple bypass pumping operations were employed to manage the existing waters so that the culvert work could be performed.
A patented portable cofferdam was installed in an existing body of water to allow for construction of a new valve chamber and a new shoreline embankment.  Bypass pumping was used to dewater the construction side of the dam initially and continuously as needed.
Dredging of the Charles River utilizing proprietary dredge pumps and divers was performed.  Work involved the removal of approximately 400 cubic yards of material.

 

Temporary Excavation Support Systems
A soldier piles and lagging system was installed near the Charles River to allow for construction of a new valve chamber.  In addition, this S.O.E. system was designed to support the loading of a Manitowoc 999 series crane, weighing over 114 tons, to be utilized during construction.
A slide rail S.O.E. system was utilized to excavate the deep sump pit for a proposed valve chamber structure.
Standard steel trench boxes were utilzed as S.O.E. to allow for the installation of 84" diameter steel pipe and valves.

Heavy Earth Work and Drainage Culverts
Work included the excavation of over 50,000 CY of material, including dredged material and the demo/removal of over 6,000 CY of ledge/rock.
Forty-three (43) existing straight and inverted siphon drain culverts were cleaned, inspected and repaired where necessary.  Work involved significant bypass pumping operation set-ups utilizing multiple 6" diameter diesel pumps to allow access for crews.  Installation of new steel bar racks on both sides of all culverts was performed while maintaining dewatering operations.

Drilled Shafts
Drilled soldier pile shafts consisting of W24X55, W24X68 & W24X117 beams in varying heights (range between 20' to 37') were installed and backfilled with flow fill.
Drilled caissons, 30" diameter, 30' depth, with 24"OD X 0.375" steel wall pipes were installed, backfilling the bottom 20' of each with structural concrete.  This system was in place to support a temporary bridge which was installed to allow for construction of a valve chamber.