Flood Hardening Program, Confidential Utility

Challenge

Electric substation facilities are among the most critical elements to our nation’s power infrastructure. Recent flood impacts and forecasts of more frequent severe weather events prompted one long-standing major utility client to request GZA’s assistance in creating a Flood Hardening Program to improve the flood resiliency of 50+ existing inland and coastal facilities in four states.

Solution

GZA’s comprehensive services spanned from program development to implementation and operation. Our scientists and engineers started with tracking Flood Insurance Rate Maps (FIRM) and relevant map amendments and revisions; reviewed current and archived facility plans; performed site visits with key stakeholders; researched flooding history; and completed a frequency / damage flood risk analysis for each site. At locations where a FIRM was not available or did not appear to represent current topography or flood risk, GZA performed hydraulic, and coastal hydrologic analyses to determine the 100-year (Base Flood Elevation) and 500-year flood elevation to assess potential impacts of flood barriers to facilities and floodways and submitted Letters of Map Amendments / Revisions to FEMA. After completing the research and analyses, GZA prioritized site needs and developed concepts and designs for flood hardening measures that fell into three general categories:

Long-term (permanent) flood hardening measures provide longer service life, require little or no storm response, and incorporate flood hardening into the substation design for optimal operations and maintenance (O&M). This approach requires the longest lead time for planning, design, permitting, and construction, and typically incurs the largest capital cost. GZA conducted detailed analysis of multiple civil design hardening alternative concepts, including one or more concepts involving installing a barrier system, raising select components, re-building at a higher elevation, or a combination. The analyses included estimated capital and design life costs, project durations, and associated risks and opportunities for each concept, followed with a ranking system to assist with the Client’s selection process.

Long-term measures have been implemented at several substations, and are planned for several more. Short-term flood hardening measures have been implemented at those substations where permanent hardening measures require long-term planning, design and construction.

Short-term (temporary) flood hardening measures have been implemented at eight substations, and are planned at three more. The short-term hardening is completed at those substations in order of highest to lowest priority in terms of flood risk and damage potential. Short-term flood hardening measures are designed with a three- to 10-year service life, and effectively reduce flood risk and damage potential until long-term measures are completed. GZA has provided support from planning through construction and operations. These temporary engineering solutions are barrier, sealing, and pumping systems designed to reduce the need for emergency manpower and equipment response prior to, and during storm events, and recovery efforts after storm events.

Interim measures are rapid-deployment barrier and pump systems established early in the flood program to protect the most critical substation components from flooding events before either the long-term or short-term hardening measures are in-place. Interim measures are portable barrier and pumping systems designed to be implemented with minimal heavy equipment and little to no site preparation or excavation. Implementation of the interim measures are more heavily reliant on manpower response. Training exercises, including mock-ups of various flood barrier systems, provided realistic guidance to assist in selecting the appropriate barrier and pump systems for each substation, and in allocating the necessary manpower and equipment resources to effectively implement the interim measures in the event of a forecasted flood event.

For each of the measures, GZA continues to interface with the client’s key stake holders including regulators, material vendors, permitting consultants, external contractors, and the client’s civil and electrical engineering, project management, O&M, construction, material staging, legal, environmental, procurement, and executive teams. Key stakeholder input, along with a solid leadership team, and GZA’s multi-disciplined design group effectively navigated the evaluation, permitting, design, construction, and implementation of all three categories of flood hardening measures. GZA’s follow-up services include engineering services during construction, as-built documentation, Activation and O&M Plans, and supporting the Client with training, storm forecasting, emergency response, and O&M. GZA also continuously re-evaluates flood risk and damage to reflect on-going substation improvements, FEMA’s FIRM updates, and updates in policy, regulation, and industry practice pertaining to future risk associated with climate change.

Benefit

GZA’s experience in flood hazard mitigation, civil engineering, and permitting support for power sector clients, as well as the firm’s keen knowledge of the regulatory environment in the client’s service territory, allowed work to proceed expeditiously. This utility’s existing and future substations will now be significantly more resilient, and their customers far less likely to experience outages or prolonged service restoration due to flooding.