If asked to imagine a brook, it is likely you would picture a stream of water flowing over rocks somewhere in the depths of the woods. Rarely would you instinctually consider a tributary of the Weymouth and Weir Coastal Drainage Area running through and underneath the urban environment that is Quincy, Massachusetts. Town Brook originates from freshwater wetlands in the Blue Hills Reservation, flowing almost four miles through urban areas to the Atlantic Ocean just south of Boston Harbor. This known spawning habitat for rainbow smelt was altered in 1998 to divert flood flows from downtown Quincy at the expense of the watershed’s quality. The City of Quincy opted to direct a portion of its $1 billion Downtown Revitalization Project funding to reroute the century-old granite Town Brook to improve stormwater runoff, address the water quality, and free up 14 acres of land for public and private redevelopment.
Reconfiguring an Urban Watershed
Town Brook serves as downtown Quincy’s primary stormwater drainage system. The effort undertaken by the city involved the construction of a new Town Brook Channel to the perimeter of the Downtown District to replace the century-old granite culvert that wound its way under numerous buildings and through these highly valued properties. The initial relocation efforts were completed in 2012 and comprised of combination of enclosed culverts and constructed channels. The work incorporated a gravel channel bottom, low flow benches and daylighting for a portion of the brook to enhance smelt spawning habitat to mitigate impacts that resulted from the original 1998 diversion project. Following of the initial phase the original portions of Town Brook remained as it served as the primary drainage course for the Downtown and hence remained a major impediment to the downtown revitalization efforts.
With an existing relationship between Quincy and Woodard & Curran, the city hired our firm as the program manager to implement the reconfiguration of downtown drainage course and decommission the former Town Brook. In this role, we created the hydraulic design of new drainage systems, developed final construction documents, reviewed third-party design contracts, conducted soil and groundwater remediation activities, construction administration and observation services, and served as liaison between the city, private real estate development companies, and existing area businesses and residents.
Given the urban setting of Town Brook, it took four months to excavate and brace roadways, utilities, and adjacent buildings in order to reroute the waterway and make way for redevelopment of 14 acres in the city’s historic downtown. The 11-foot by 6-foot granite box culvert was replaced by 9-foot by 5-foot box culverts for approximately 1,100 feet. In some areas. Much of this work abutted structural foundations, such as Nova Residences – a five-story apartment building, and passed below an enclosed public walkway/atrium. Due to the proximity of existing infrastructure, the culvert replacement required underpinning of adjacent buildings and extensive cribbing and shoring of the existing roadway and utilities under Hancock Street as the transition of the culvert to its new alignment took place.
As work continues in 2019 to finalize the project, we’re incorporating stormwater quality measures to improve water quality downstream for the smelt spawning habitat. This includes installing more than 2,000 feet of stormwater collection systems, reducing impervious surface areas, adding generous landscaping and tree plantings, incorporating green- and gray- infrastructure stormwater treatment systems, brook baseflow enhancements, and soil remediation for lead and petroleum impacted soils.
Unique Public/Private Partnership
While this aspect of the city-wide revitalization project came with a large investment in stormwater infrastructure, the result is an improved drainage system for urban runoff, better management of the Town Brook watershed, and a thriving downtown economy translating into revenue for Quincy. The relocation of Town Brook and demolishing of existing buildings above the remnants of its former route made way for public and private land development, including the addition of a 712-space parking garage, a 120-unit condominium tower, a medical office building, hotel, market rate workforce housing including a 171-unit apartment building, new retail and restaurant businesses, and nearly two acres of public parkland.
A major consideration during the project planning process was to enable the construction of the Nova Residence and public atrium simultaneously with the drainage relocation. The city turned to a public-private partnership under special legislation to allow the Nova Residence developer, LBC-Boston, to construct the drainage relocation. Serving as the city’s consulting engineer, Woodard & Curran developed a working relationship with the developer to develop a Guaranteed Maximum Price (GMP) contract for the public infrastructure improvements. This allowed for coordination with ongoing work with Town Brook and simultaneous, ongoing private construction. This eliminated many potential conflicts inherent with multiple contractors working on the same project site and allowed for efficient construction in both public and private sectors, ultimately expediting the redevelopment and revitalization of this area.