8j. Memo
Tyee Pond Effluent Pipe Replacement Project
COMMISSION AGENDA MEMORANDUM Item No. 8j ACTION ITEM Date of Meeting April 26, 2022 DATE: April 15, 2022 TO: Stephen P. Metruck, Executive Director FROM: Eileen Francisco, Interim Director, AV Facilities & Capital Programs Wayne Grotheer, Director, Aviation Project Management Group SUBJECT: Tyee Pond Effluent Pipe Replacement (C801173) Amount of this request: $390,000 Total estimated project cost: $2,540,000 ACTION REQUESTED Request Commission authorization for the Executive Director to complete design for the Tyee Pond Effluent Pipe Replacement Project located just south of the Seattle-Tacoma International Airport in the amount of $390,000. The total estimated project cost is $2,540,000. EXECUTIVE SUMMARY The Tyee Pond stormwater pond and its control structures are a regional detention facility that the Port of Seattle owns, maintains, and operates. This detention facility is regulated by the Department of Ecology (DOE) Dam Safety Program. The downstream effluent pipe is over 30 years old and shows signs of damage and deterioration. The pipe needs to be replaced to ensure that the detention facility and downstream effluent pipe can function as designed for the next 50 years. Emergency repairs have already been needed and DOE issued a requirement for a permanent repair to be completed by 2025. JUSTIFICATION This project will support the following Century Agenda goals: To be the greenest and most energy-efficient port in North America by meeting or exceeding agency requirements for stormwater leaving Port-owned or operated facilities. To become a model for equity, diversity, and inclusion by increasing utilization of Women and Minority Business Enterprise (WMBE) and Disadvantage Business Enterprise (DBE) firms and eliminating disparity of access to opportunities. In December 2021, a pipe assessment was completed that examined the existing pipe downstream of the repaired section (approximately 382 linear feet). The Pipe Assessment Report noted joint separation, deformation, and corrosion in the downstream pipe and recommended Template revised January 10, 2019. COMMISSION AGENDA Action Item No. _8j_ Page 2 of 4 Meeting Date: April 26, 2022 replacing the entire pipe. If the pipe completely fails, the hydraulics of Des Moines Creek will be affected impacting the downstream salmon bearing creek habitat. In the worst -case scenario, with the detention facility at full capacity, the pipe failure can result in the failure of the Tyee Pond embankment sending several thousand gallons of stormwater towards downstream residents adjacent to Des Moines Creek in an uncontrolled fashion. Diversity in Contracting The design of this project will utilize an existing indefinite delivery indefinite quantity (IDIQ) contract that has an established WMBE goal of 10%. The project team will work with Diversity in Contracting department to establish additional WMBE goals within the construction phase of this effort. DETAILS Tyee Pond is located south of Seattle-Tacoma International Airport and is located on the east fork of Des Moines Creek flowing south from Bow Lake. The pond has a capacity of 19.7 acre-ft and is therefore regulated by DOE Dam Safety program. The pond and effluent pipe were originally constructed in the late 1980's. In 2020, emergency repairs were made to a small section of the pipe (approximately 32 linear feet) that was leaking and causing sinkholes to appear on the pond embankment above the pipe. DOE accepted the interim repairs but required a permanent repair by 2025. Scope of Work The project will replace the entire downstream effluent pipe with a 72-inch diameter reinforced concrete pipe. In addition, two manhole structures will be added to the northern section of the pipe to provide energy dissipation. Schedule Commission design authorization 2022 Quarter 2 Design start 2022 Quarter 2 Commission construction authorization 2023 Quarter 1 Construction start 2023 Quarter 2 In-use date 2023 Quarter 4 Cost Breakdown This Request Total Project Design $390,000 $625,000 Construction $0 $1,915,000 Total $390,000 $2,540,000 Template revised June 27, 2019 (Diversity in Contracting). COMMISSION AGENDA Action Item No. _8j_ Page 3 of 4 Meeting Date: April 26, 2022 ALTERNATIVES AND IMPLICATIONS CONSIDERED Alternative 1 No improvements Cost Implications: $0 Pros: (1) Requires no capital investment Cons: (1) Does not address integrity of Tyee Pond dam required by DOE (2) Does not address long-term viability of the storm water infrastructure This is not the recommended alternative. Alternative 2 Utilize the bypass system Cost Implications: $702,000 Pros: (1) Requires less capital investment Cons: (1) Does not address integrity of Tyee Pond dam required by DOE (2) Does not address long-term viability of the storm water infrastructure (3) Potential to damage downstream salmon bearing creek habitat (and trigger fines) This is not the recommended alternative. Alternative 3 Replace the effluent pipe Cost Implications: $2,540,000 Pros: (1) Permanent solution ensuring Tyee Pond dam integrity (2) Offers maximum stormwater flow control from the Tyee Pond (3) Doesn't adversely impact flow to downstream salmon bearing creek Cons: (1) Requires greater capital investment (2) Permits may be required by the Corps of Engineers to complete this project potentially delaying project completion by a year. This is the recommended alternative. Template revised June 27, 2019 (Diversity in Contracting). COMMISSION AGENDA Action Item No. _8j_ Page 4 of 4 Meeting Date: April 26, 2022 FINANCIAL IMPLICATIONS Cost Estimate/Authorization Summary Capital Expense Total COST ESTIMATE Original estimate $2,791,000 $0 $2,791,000 Current change ($251,000) $0 ($251,000) Revised estimate $2,540,000 $0 $2,540,000 AUTHORIZATION Previous authorizations $235,000 $0 $235,000 Current request for authorization $390,000 $0 $390,000 Total authorizations, including this request $625,000 $0 $625,000 Remaining amount to be authorized $1,915,000 $0 $1,915,000 Annual Budget Status and Source of Funds This project CIP #801173 was included in the 2022-2026 capital budget and plan of finance as a budget of $2,791,000. A budget decrease of $251,000 was transferred to the Aeronautical Reserve (CIP #800753) resulting in a zero-net change to the Aviation capital budget. The funding source for this project will be the Airport Development Fund (ADF) and revenue bonds. Financial Analysis and Summary Project cost for analysis $2,540,000 Business Unit (BU) Airfield Movement Area Effect on business performance NOI after depreciation will increase due to inclusion of (NOI after depreciation) capital (and operating) costs in airline rate base. IRR/NPV (if relevant) N/A CPE Impact $.01 in 2024 Future Revenues and Expenses (Total cost of ownership) Operations and maintenance costs are anticipated to be minimal. The pipe will be video inspected once every 3-5 years. ATTACHMENTS TO THIS REQUEST (1) Vicinity Map PREVIOUS COMMISSION ACTIONS OR BRIEFINGS None Template revised June 27, 2019 (Diversity in Contracting).
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