Town Brook at diversion tunnel at Quincy

Beneath the bustling city of Quincy, hidden from the everyday hustle, flows Town Brook. Town Brook at diversion tunnel at Quincy isn’t your typical babbling brook. It’s a vital artery, a testament to human ingenuity and the delicate balance between urban development and environmental preservation. Town Brook begins its journey in the tranquil Blue Hills Reservation. It meanders through nearly four miles of urban landscape before finally reaching the Atlantic Ocean, just south of Boston Harbor. This waterway, a known spawning ground for rainbow smelt, faced a critical juncture in 1998. A decision was made to divert flood flows away from downtown Quincy. This decision, while protecting the city center, unfortunately impacted the overall health of the watershed. Enter Quincy’s ambitious $1 billion Downtown Revitalization Project. A portion of this funding was allocated to reroute the century-old granite channel of Town Brook. The goals were threefold: improve stormwater runoff, address declining water quality, and free up valuable land for redevelopment. The initial phase of this project, completed in 2012, involved constructing a new Town Brook channel along the perimeter of the Downtown District. This replaced the old granite culvert that snaked beneath buildings and through valuable properties. The new design incorporated a gravel channel bottom, low flow benches, and daylighting sections to enhance the smelt spawning habitat. This was a crucial step in mitigating the negative impacts of the 1998 diversion. The original sections of Town Brook, however, remained a significant obstacle to the revitalization efforts. The city brought in Woodard & Curran to manage the reconfiguration of the downtown drainage course and decommission the old Town Brook. This complex undertaking involved designing new drainage systems, preparing construction documents, overseeing soil and groundwater remediation, and coordinating with various stakeholders. Imagine the logistical challenge of working in a dense urban environment. It took four months just to excavate and brace roadways, utilities, and adjacent buildings to prepare for the waterway’s rerouting. The old 11-foot by 6-foot granite box culvert was replaced with a slightly smaller 9-foot by 5-foot culvert for approximately 1,100 feet. In some sections, the work was incredibly close to existing building foundations, like the Nova Residences, a five-story apartment building. The new culvert even passed beneath an enclosed public walkway. This proximity required underpinning adjacent buildings and extensive shoring of Hancock Street during the culvert’s transition. As work continued into 2019, stormwater quality measures were implemented. Over 2,000 feet of stormwater collection systems were installed. Impervious surface areas were reduced. Landscaping and tree plantings were added. Green and gray infrastructure stormwater treatment systems were incorporated. These efforts, combined with brook baseflow enhancements and soil remediation, aimed to improve water quality downstream for the smelt spawning habitat. The Town Brook at diversion tunnel at Quincy project, a significant investment in stormwater infrastructure, exemplifies the delicate balancing act cities must perform. The project not only improved urban runoff and watershed management but also fostered economic growth by enabling public and private land development. The relocation of Town Brook made way for a parking garage, a condominium tower, a medical office building, a hotel, new housing, retail spaces, restaurants, and even public parkland.