2010/09/15 Council Agenda Packet

• Exhibit A-2 City of Everett Amendment No. I North End Combined Sewer System Evaluation, UP 3398- 11 Scope of Services Otak Project No. 31520 The City of Everett has a combined sewer system in the north area of the city.Historically,there have been periodic sewer backups and basement flooding incidents attributed to heavy rainfall in various locations. However, one particular area immediately southeast of the Providence Everett • Medical Center (PEMC) (see attached Figure 1) has experienced multiple incidents affecting a relatively large group of homes. In 2007-2008 the City constructed the Sewer I Project,which increased most pipe sizes from Oakes Avenue at 14th Street to the 17th Street Interceptor (see Figure 1). Nevertheless,the neighborhood still experienced numerous sewer backups caused by rain storms on October 4,2008 and June 9, 2010. During this timeframe, expansion of the PEMC has added new sanitary and stormwater discharges to the north area of Everett (study area) system. Otak is currently contracted with the City of Everett(the City) to provide engineering analysis and design of the Sewer System Replacement and Capacity Improvements Project(Sewer L Project), City UP 3398. The Sewer L North Area Project proposes to replace existing sewer lines and install new sewer lines along Lombard Avenue and on other nearby streets as well as re-routing flows from the PEMC utility plant. The City has requested this amendment to the Sewer L project, to analyze combined sewer flooding in the study area as.shown in Figure 1, to evaluate alternatives to manage or eliminate the flooding, and to then recommend an alternative from those evaluated. A future phase may include preparing construction documents for the improvement alternative selected by the City.A separate scope of work will be prepared for the design of the preferred alternative as selected by the City.The City goals for the project are to have the Sewer L North Area improvements begin construction in the fall of 2010, and to possibly have other system upgrades designed in early 2011 and constructed immediately thereafter. The work to be done under this amendment (North Everett Combined Sewer System Evaluation) is organized into three (3) phases as follows: Phase 1—Evaluation of Existing Conditions and Early Action Phase 2—Evaluation of Near term and Long-Term Actions Phase 3—Construction Plans (Amendment to be scoped for City selected improvements) City of Everett—North Everett Combined Sewer System Evaluation 3 otak K:\project\31500\31520\Contract\Amendll_NAreaFlooding\31520 Everett Sewer Amendment 1 Scope082510.doc