2011/10/19 Council Agenda Packet

EXHIBIT A-3 SCOPE OF WORK Task 04—Wetlands Investigation No additional work is anticipated under this task. Task 05—Survey No additional work is anticipated under this task. Task 06—Pipeline Condition Assessment No additional work is anticipated under this task. Task 07—Design The following tasks are needed to complete the 100%design: • Geotechnical—verify and finalize trenching, shoring, excavation elements • Pipeline o Finalize pipe thickness calculations o Finalize load and thrust calculations o Revise tapping,dechlorinization,and connections based on a reduced maximum down time on the 5-Line(from 24 hours to 10 hours) • River Hydraulics o Finalize river diversion structure design o Finalize bank restoration design • Civil o Revisions to grading,and erosion and sediment control plan based the Snohomish County grading permit(LDA)requirements. These requirements have been updated since 2008. The Design Report(Task 08)will include design summary and calculations included as appendices. The design will be presented on the Construction Plan Drawings(Task 09). Task 08—Design Report The design report will be finalized and will provide documentation and write-up for design revisions based on the final design and include 95%review comments from the City. Also,decreased dewatering time for the 5-Line will be evaluated,which may require a change in the design of the dechlorination vault. For the 60%design, a 5-Line down time of 24 hours was assumed;this has been revised to 10 hours. The dechlorination vault calculations will evaluate the time it will take to dewater Pipeline 5. Also under consideration is the amount of initial pressure in the dewatering pipes when dewatering begins. The geotechnical investigation completed in October 2010 included development of boring logs; however, sieve analyses were not assumed in the scoping effort for that work. To be consistent with other geotechnical data, sieve analyses will be prepared for the 2010 boring. These data will be provided in the design report. Pipe design calculations originally assumed 42,000 psi steel. During 95% design review,a value of 50,000 psi was provided by the City. URS will update calculations to reflect 50,000 psi steel. S:\RHefti\zProjects\3251_Line5_Pilchuck\Consultant_contract andment3\Pilchuck Open Cut Design Scope 09-27-11-rev2.docxPage 3 of 7