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The original item was published from 10/16/2020 3:22:37 PM to 1/17/2021 12:05:16 AM.

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Environmental Services

Posted on: October 16, 2020

[ARCHIVED] Massive Mead-Mt. Spokane Sewer Extension Projects Completed!

Siphon and Valve Vault Under Construction

The 2018-2020, 5-Phase Mead-Mt. Spokane Sewer Extension Projects included a new pump station, an inverted siphon, Little Spokane River bridge crossing, 6 trenchless undercrossings of a creek/railroad/highways, 125 manholes, 31,000 LF of gravity pipelines and 12,500 LF of force main to convey wastewater from the Mead-Mt. Spokane area to Spokane County’s existing sewer system in Little Spokane Drive.  Timing was critical, as operation of the first 4-phases was required prior to completing the fifth.  All five phases are now complete, and with the assistance of Wastewater Operations, sewage has been successfully rerouted from the County’s last interim package treatment plant, to the new Mt. Spokane Park Drive Pump Station.  

Successfully overcoming the challenges of working from home, the Peone Pines Connection force main Project went out to bid in April.  After navigating the governor’s orders and coordinating with contractors, construction resumed on MMS Package 1 and Package 2.  The social distancing requirements delayed the pump station, but with masks on. we successfully started the new pump station in June.  After securing permits from the Burlington Northern Santa Fe Railroad (BNSF), the boring under the tracks was completed in July.  While the virus did cause delays with getting materials, once they were delivered the gravity sewer and force main were installed, allowing the Peone Pines connection to be completed in September!

The design and construction of our inverted siphon was a collaborative effort with considerable contributions from Wastewater Operations.  Sewer flows are conveyed in “doses” under Little Deep Creek and over the Little Spokane River via a gravity driven inverted siphon.  With the recent addition of flows from the Peone Pines area, the siphon went from dosing three times a day to seven.  The

siphon has been in operation for one year and Wastewater Operations reports it is doing a great job! 

Wastewater Operations also supported our efforts by video-taping six miles of newly installed sewer mains.  The Design Section then reviewed the videos for quality control prior to acceptance.  The MMS project area also included the activation of several “dry” sewer systems installed in the 1970s-1980s.  To ensure the viability of these old sewer systems, including stubs, we coordinated the video inspection of over 300 dry service lines, repairing issues discovered along the way.


The Design Section also collaborated with the Public Works Department to utilize their services for inspection, construction management, and surveying on various phases of work.


The MMS projects provide sewer service to many residences and businesses in the Mead area, eliminating septic systems and their negative impacts to the area’s groundwater.  The projects also lead to a reduction of the pollutant load reaching the Spokane River and Lake Spokane.  The abandonment of the Peone Pines Treatment Plant eliminates the need for operational and regulatory activities at that facility.


With the completion of the MMS projects, our permitting team has been busy issuing sewer connection permits in the MMS area.  One of the positive results of COVID is that as a department we have made significant improvements in our ability to issue permits electronically.  Utilizing both email and DocuSign, we have processed sewer permits, connection charge agreement (CCA) forms, and gather all the required signatures and payments electronically.  


We are now contacting roughly 600 property owners in the project area and providing information about how to connect, the timeline and connection requirements.  This project will generate hundreds of permits and sewer connection charge agreements (CCA’s) in 2021.  Moving forward, we are continuing to refine our new electronic document handling process, as it is proving to be more efficient for our team! 



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