Breach Analysis, Inundation Mapping and Emergency Action Plans for Massachusetts Water Resources Authority Dams

The Massachusetts Water Resources Authority (MWRA) owns numerous dams throughout the Commonwealth of Massachusetts.  MWRA engaged GZA to perform  breach analysis, develop inundation maps and develop Emergency Action Plans for the following structures: Chestnut Hill Reservoir Dam, Fells Reservoir Dam #6, #7 and #8, Spot Pond Dam No. 1, Spot Pond Dike #4 and #5.

GZA used the HEC-GeoRAS Interface, which allows the preparation of geometric data for import into HEC-RAS and processes simulation results exported from HEC-RAS.  We modeled the fair weather and wet weather failure of each dam and routed the floodwave along the downstream floodplain.  We performed the modeling in accordance with FERC ‘s Engineering Guidelines for the Evaluation of Dam Safety Projects.  The results of our modeling were portrayed on a series of inundation maps.  The inundation maps display the extent of impact and provide information about the peak flood elevation, floodwave arrival time, etc. 

GZA developed an Emergency Action Plan (EAP) for each structure that follows the format of FEMA 64.  GZA engaged in extensive coordination with MWRA and the impacted communities to understand and document the notification and response procedures. 

GZA is in the process of presenting the EAPs to the downstream communities and state emergency responders at Emergency Action Plan Orientation Meetings.