Consideration of Earthquake Hazard Mitigation as a Component of Water/Wastewater Facility Modification and Expansion

According to authorative sources within AWWA, WEF, ASCE, AwwaRF, GAO, and many other organizations, water and wastewater systems will undergo literally unprecedented modernization and growth over the next two decades. This modernization and growth is being fueled by a number of factors including:Emergence of cost effective new treatment technologies;Dramatically increased water demand;Aging infrastructure;Recently, security concerns.In order to satisfy multiple concurrent goals, water and wastewater districts are often required to modernize existing facilities, as well as build new facilities. When existing facilities are modified (in conjunction with or separate from new facility construction) a window of opportunity exists for addressing seismic risk mitigation issues in a very cost effective manner.In order to demonstrate this process, the authors describe two projects and possible application of techniques used on these projects for any water and wastewater upgrade projects in seismically active areas.One project resulted specifically in a document entitled: “Metropolitan Water District of Salt Lake & Sandy (MWDSLS) Seismic Design Policy” (MWDSLS 2004). This document interpreted the many varied sources for seismic retrofit and new design including: WEF, AWWA, AwwaRF, FEMA, IBC, as well as recent research not yet in seismic design standards. Practical measures for seismic retrofit of existing treatment facilities, as well as new design of treatment and distribution facilities, were developed.The MWDSLS Seismic Design Policy criteria document was awarded the National Award of Merit in the category of Mitigation at the National Earthquake Engineering Conference in St. Louis, Missouri in September 2004.The second project involved combined seismic retrofit, security improvements, and facility expansion for the Jordan Valley Water Conservancy District in Salt Lake City, Utah. Facility expansion and concurrent seismic improvements are described, however security improvements are confidential.These Water Districts were in the process of confirming long and short-term capital improvement plans (CIPs) driven mostly by facility process changes and capacity expansion needs. As a part of confirming these CIPs, both the authors performed detailed seismic risk assessments for both utilities. Results of these assessments indicated that facility expansion and modernization needs could be accomplished much more cost effectively by performing process and expansion retrofits concurrent with seismic retrofit measures (versus construction of new facilities). The studies and subsequent designs addressed many facility components of which two are selected for this paper: (1) Retrofit of a inlet control structure concurrent with change of use to a ozoneation structure and (2) seismic retrofit of an Administration Building concurrent with facility expansion and installation of centralized security measures (not discussed due to confidentiality restrictions).