Emergency Bow Brook culvert work underway; city permitting and future reroute discussed

District facilities staff told the capital facilities committee on Aug. 25 that emergency work to repair a compromised section of the Bow Brook channel near Concord High School began in early August after expedited permitting with the New Hampshire Department of Environmental Services. The district engaged Merrill Construction to install a vertical structure and pipe work and to begin backfilling once concrete cures. Matt Cashman (administration) said the district requested and received emergency permitting from New Hampshire DES after multiple exchanges with the state and that crews began work about four to five days before the meeting. “We essentially had to take over that whole parking lot,” Cashman said, describing temporary parking arrangements (20 spaces on the east side of Westbourne Street extended through Sept. 5) that the city provided while work is underway. Cashman said crews will place one more vertical structure and pour the concrete; after the concrete cures they plan to backfill and pave the area. He described a later-stage option discussed with the city engineer to reroute Bow Brook around the high-school footprint using new pipe and to abandon and fill the existing pipe beneath the building. That concept was shown to committee members as a yellow line on project sketches and was described as preliminary; Cashman said the city was “agreeable” to evaluating it but that ownership and any cost-sharing would be worked out with the city. Staff reported a closed-circuit-video (camera) inspection of the existing line that showed it to be intact at points beyond the school property; the video evidence is recorded by distance and time and was reviewed by staff, a private inspection firm and the city engineer. Wind River (inspection firm name provided by staff) did the inspection, and Cashman said multiple reviewers did not identify compromised sections beyond the immediate repair area. Committee members asked about long-term inspection schedules and contingencies if a failure occurred midyear; Cashman said the district would mobilize available parts and crews and go into an emergency response mode if necessary and that the current work targeted the most compromised surface sections. He cautioned that the corridor extends roughly 800 feet, that older construction placed the channel under a spread footing during a 1990s addition and that replacing the full length would be a future, larger effort. The committee did not take separate formal votes on the emergency repair at the meeting; Cashman reported staff awarded the repair contract to Merrill Construction and began material acquisition prior to the meeting.