BETA was selected by the Town of Bristol to perform a drainage analysis of the two square miles watershed that contributes to the Silver Creek, which is a tidally influenced water body. The primary objective of the study was to determine the causes of flooding within the watershed and recommend improvements to mitigate the flooding problems during the 2, 10, and 100-year design storm event.
The existing condition analysis was completed utilizing a combination of HydroCAD and HEC-RAS software. Watershed hydrologic characteristics were input into HydroCAD to estimate the peak discharge rate for the 2, 10, and 100-year storm events. Based on the peak flow from HydroCAD, HEC-RAS was utilized to analyze the hydraulic capacity of the open channel river and floodplain portions of the Creek as well as the bridge and culvert crossings.
The results of the analysis identified capacity deficiencies within the drainage network that contribute to flood conditions within the watershed as well as the diminishing capacity of Silver Creek due to the tidal influence from Bristol Harbor.
BETA utilized the model to evaluate alternatives to mitigate the flooding and increase the capacity of the creek, including upgrading portions of the drainage system while dredging sediment from other portions of the creek.