TIC 2017-11-14 Item 2D - Contract Amendment #1 - Riverton Creek Flapgate Removal Design with OTAK Inc

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City of Tukwila Public Works Department - Robin Tischmak, Acting Director Allan Ekberg, Mayor INFORMATIONAL MEMORANDUM TO: Transportation and Infrastructure Committee FROM: Robin Tischmak, Acting Public Works Director BY: Mike Perfetti, Habitat Project Manager DATE: November 9, 2017 SUBJECT: Riverton Creek Flapqate Removal Project Project Number 99830103 Contract 17-070, Amendment No. 1 ISSUE Approve Supplemental Agreement No. 1 to Contract No. 17-070 with OTAK, Inc. BACKGROUND In May 2017, the City entered into a consultant agreement with OTAK, Inc. for design services of the Riverton Creek Flapgate Removal Project. This project will remove two culverts and flap gates where Riverton Creek joins the Duwamish River. A new trail bridge will be installed over the new open channel which should improve fish passage. DISCUSSION Four additional service items have emerged since the OTAK contract was initiated: 1. OTAK has determined that the geotechnical investigations and hydraulic modelling were lacking key information needed for the design of the new pedestrian Green River Trail bridge, modifications to the TIB bridge abutment, and channel bank stabilization. 2. The City was notified by our funding partner, the State's Recreation and Conservation Office (RCO), that cultural resource review will be required. 3. The Salmon Recovery Funding Board recently approved with conditions the City's RCO grant application stating that "this project needs to demonstrate that increasing fish access to Riverton Creek will not increase toxic exposure to salmonids from stormwater inputs...", meaning that additional stormwater water quality modeling is necessary. 4. Staff requested that OTAK conduct a brief alternative analysis exercise, and shift budget from other tasks to do so. To partially offset cost increases, staff will take on a handful of items that were previously in the OTAK scope including permit work and landscape design. OTAK is providing a scope of services that includes additional geotechnical exploration, hydraulic modeling, cultural resource investigation, and stormwater modelling. The additional work and completion of the remaining tasks will require additional contract time and Supplemental Agreement No. 1 will extend the time for performance to April 30, 2019. FISCAL IMPACT The current agreement with OTAK is for $105,363.00 and with Amendment No. 1 for $39,993.00, the total contract amount will be $145,356.00. To fund Amendment No. 1, the project will utilize the 2018 CIP construction budget of $200,000. Two pending grants, totaling $846,965.00, are expected to be executed in 2018, which will replace the borrowed City construction funds. Agreement 2017-2018 Budget Original OTAK Contract $105,363.00 $108,00.00 OTAK Amendment #1 39,993.00 200,000.00 $145,356.00 $308,000.00 RECOMMENDATION Council is being asked to approve design Supplemental Agreement No. 1 for $39,993.00 with OTAK, Inc. for the Riverton Creek Flapgate Removal Project and consider this item on the Consent Agenda at the November 20, 2017 Regular Meeting. Attachments: Page 108 of 2017 CIP OTAK Supplemental Agreement #1 W:\PW Eng \PROJECTS \A- DR Projects\Riverton Flap Gate Removal (99830103 98-DR03)\Consultant Selection\Phase 2\contractAmendment #11Info Memo for Supplement #1.docx 87