Will the pedestrian tunnel flood?

While one of the objectives of the Brentwood Bound Plan is to mitigate the base flood event (1% annual chance) along Deer Creek south of Manchester Road, the pedestrian tunnel will be approximately 12 feet lower than Manchester Road at the point of crossing, and it is possible for a flood event to exceed project design constraints. Check valves have been incorporated into the flood mitigation design to prevent storm sewer backups from the flood mitigation area into the pedestrian tunnel; however, a significant area tributary to Deer Creek resides north of Manchester Road. Storm sewers are typically designed to convey more frequent events, and when larger events occur, flood waters can sometimes be conveyed overland to their downstream most point. Because of the low elevation of the tunnel, it may accumulate some of this water during large storm events. Flooding can be extremely unpredictable, and because the pedestrian tunnel is connected to the new Brentwood Park and the flood mitigation area of the trail system – which will be subject to more frequent flooding – the tunnel will be closed off during any significant storm event.

Show All Answers

1. Where is the pedestrian tunnel located?
2. What are the dimensions of the pedestrian tunnel?
3. Why is there a pedestrian tunnel under Manchester Road at Mary Avenue and not a street-level crossing?
4. How will the Manchester Road elevation change to accommodate the tunnel?
5. How will water be kept out of the pedestrian tunnel?
6. What safety features will be included in the pedestrian tunnel?
7. Will the pedestrian tunnel flood?
8. How is the pedestrian tunnel being funded?