North Allston Storm Drain Extension Project (NASDEP) Pre-Construction

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The North Allston Storm Drainage Extension Project (NASDEP) extends the existing Boston Water and Sewer Commission (NWSC) drainage infrastructure through Harvard’s future Allston Landing North Campus, across Soldier Field Road and to a new outfall in the bank of the Charles River in Allston, MA. The project includes a large diameter precast concrete pipe, box culverts, ancillary structures, and ACM soil excavation.

Due to the presence of urban fill and organic deposits, timber piles were selected as the foundation type to support portions of the new concrete pipe and box culverts across the site. UFS performed a preconstruction testing program to maximize the design capacity of the timber piles in both the marine sand and the stiff, overconsolidated upper clay layer. Timber piles were installed using a Junttan PM20 pile driving rig.

Various types of excavation support systems were installed to facilitate utility installation in asbestos contaminated soils (ACM). A secant pile wall was installed at an area of the site in close proximity to existing sensitive utilities. UFS crews received specialized training to install the piles adhering to a Non-Traditional Work Plan (NTWP) while working in the ACM soils. Other support of excavation systems included internally braced steel sheet piles driven into marine clay to provide water cutoff during excavation and installation of new utilities.

This complex project required close coordination with Harvard Capital Projects and its consultants, along with regulatory agencies including BWSC, MWRA, Massachusetts Department of Conservation and Recreation, and MassDOT.