Sewer Pump Station Generator Replacement
Project Status
Click here to see status updates.
Project Details/Neighborhood
Work will take place at the following City of Mercer Island Sewer Pump Stations (PS): PS 23: 5406 96th Ave SE PS 25: 4266 E Mercer Way
Background
The Department of Ecology requires emergency backup power to keep pump stations operational and flowing during grid outages. For Mercer Island, backup power comes in the form of diesel generators located mostly in underground vaults near each respective pump station (a few generators are above ground). To meet minimum reliability requirements, the Capital Improvement Program (CIP) has funded a systematic sewer system generator replacement program since the 2009-2010 biennium. The underground standby generators at sewer Pump Stations 23 and 25 were last replaced in 1988 and 1998, respectively. Of the 18 stations, they are the last remaining generators requiring replacement in the current cycle.
Description
This project involves replacing the 40-kilowatt diesel generators located in the underground vaults of sewer pump stations 23 and 25. To enable this replacement, the vault lids at both stations will be removed and replaced. The ventilation and electrical systems will also be rerouted and relocated to comply with current local, state, and federal regulations. Both stations will need to be temporarily taken offline for the electrical work, during which a complete temporary sewer bypass system will be installed. This system will use above-ground pumps and piping to divert sewer flows around the stations. Upon completion, the new generators and their components will be tested and integrated into the City’s Supervisory Control and Data Acquisition (SCADA) network.
Construction Project Timeline
Planning/Design (Q3 of 2021 - Q2 of 2024)
Under Construction (Q4 of 2025)
Estimated Budget
$1.1M
Contact
Christopher Marks, City of Mercer Island Utilities Engineer: chris.marks@mercerisland.gov
Status Updates
September 5, 2024
Two contractor bids were received for this project, and on July 16th, the City Council awarded the construction contract to Valley Electric Co. of Mount Vernon for $879,947.00. A pre-construction meeting was held last week with City staff, RH2 Engineering (design consultant), and project managers from Valley Electric. During this meeting, we discussed project scheduling, construction sequencing, coordination items, permitting, and site constraints. Construction is expected to commence on October 1, 2025. This timeline accounts for site working restrictions and the lengthy delivery lead times for generators and associated electrical equipment, which can extend up to 32 weeks.
June 20, 2024
This project is currently being advertised for bids on the City’s Bids/RFP webpage, the Seattle Daily Journal of Commerce, and on the Builder’s Exchange of Washington. Sealed bids will be received until 2:00 PM on June 27, 2024.
May 22, 2024
100% percent bid plans and specifications were received by the City this week. Staff will review and coordinate any final changes with RH2 Engineering to get the package bid-ready.
May 2, 2024
The City’s contracted arborist for the project, Urban Forestry Services | Bartlett Consulting (UFS|BC) has taken inventory of the trees within the project limits. UFS|BC’s recommendations for tree protection and/or removal are necessary to secure project approval from the City’s planning department. RH2 Engineering, continues work to incorporate the City’s latest plan review comments into the design.
October 2023
Staff from RH2 Engineering’s design team re-visited pump stations 23 and 25 this month to ensure all site-specific challenges are addressed during final design. Delivery of 100% project design documents is expected by the close of 2023.
August 2023
A project milestone was reached this month with RH2 Engineering’s delivery of 50% design documents. Based on the preliminary design requirements, City staff can now begin procurement of long lead time items such as the diesel generators and transfer switches for both pump stations.
July 2023
RH2 Engineering has provided the technical memos necessary for processing of the Shoreline Exemption Permits at both pump station 23 and 25. City staff will work to finalize the permits in the following weeks. While updated fire codes, generator design, and access requirements have delayed the project, delivery of 50% design plans and specifications by RH2 Engineering are expected by middle August.
April 2022
RH2’s staff went out in March to pump stations 23 and 25 to perform a critical areas evaluation associated with environmental permitting requirements. They will continue to assist with permits for this project.
February 2022
A Shoreline Exemption Permit is required for this replacement. This entails a critical area review by a qualified professional. The City has amended the scope of work to add RH2’s permitting assistance.
Staff also met with RH2 and will look into pre-purchasing the equipment ahead of construction, as the lead times are over 52 weeks.
November 2021
In October, RH2 Engineering visited both pump station sites. The project will replace both generators almost like-for-like back into the existing underground vaults, however, the City was recently informed that the new generator options are of a slightly larger size and this may impact the electrical spacing requirements in the underground vaults. Additionally, fire codes have changed, so external ventilation for the fuel tanks is needed. Before design work continues staff will need to discuss possible alternative options.
September 2021
This project will focus on replacing two permanent back-up generators at pump stations 23 and 25. The scope and fee for this project has been finalized and the project is expected to start in September 2021.
Project Location (369 KB)