Wastewater Treatment Plant Upgrades

Throughout discussions with Sultan community members regarding the “Downtown Visioning Project” it was reiterated the city must “invest now for the long-term” growth of Sultan. City staff and council are committed to investing in our community. There is an undeniable urgent need for upgrades to the WWTP to manage the growth of Sultan. City staff are working diligently to secure federal and/or state funds to partially fund upgrading Sultan’s WWTP in 2022.

In 2019, an influx of housing developments began and there are now over 473 new houses since 2019. Monthly, during 2021 the city bumps above 85% of our permit limit as established by the Washington State Department of Ecology (DOE). Our population increase creates an essential need to upgrade the Wastewater Treatment Plant (WWTP) to ensure the continued safe and swift processing of Sultan wastewater. Per DOE guidelines, the city is required to start planning to upgrade a WWTP to manage upcoming growth once the WWTP hits 85% of its capacity limit.

The city ensures new housing developments contribute fair and adequate sewer connection fees towards investments in our current infrastructure and upgrades to our WWTP. A financial consultant analyzed our current sewer system infrastructure to determine its value, the projected needs of the community, and the cost. The council reviewed the cost of a new house connection to Sultan’s sewer system and adopted the fees this by ordinance. On June 25th, 2020, the connection fee increased from $12,895 to $15,885.

Normal wear and tear on Sultan’s entire WWTP initially built in the late 1990’s and an increase in our population renders our current WWTP unable to keep up with the foreseeable demand. To maintain the needs of current and future Sultan residents and businesses, and to stay within the DOE guidelines for processing wastewater, we need a substantial upgrade.

A few examples of recent WWTP parts replacement events include February 2018, installed two new “Ultrasonic Level Sensors; ” April 2018 a “Screw Pump Repair” to keep the plant functioning; and on November 14th, 2018, the WWTP centrifuge stopped working entirely rendering the city unable to complete the final stage of the wastewater treatment process. Sultan City Council Agenda Bill No. 18-28, Action 9, 11/15/2018 explains the unanticipated emergency repairs.

The WWTP centrifuge emergency highlighted the need for city staff to take a hard look at the continued growth of Sultan and the need to upgrade the WWTP. Sultan City Council Agenda Bill No. 20-73 dated 11/5/2020 explains the steps taken to hire an engineering firm in 2020 to design necessary upgrades to the WWTP. The city’s engineering firm Gray and Osborne is 60% complete with the design of upgrades to Sultan’s WWTP as seen in bold in the image below.

WWTP Upgrades (JPG)

There is an undeniable urgent need for upgrades to the WWTP to manage the growth of Sultan. City staff are working diligently to secure federal and/or state funds to partially fund building a new WWTP in 2022.

Posted 10/8/2021


  1. Nate Morgan

    Public Works Director
    Phone: 360-793-2262

Current WWTP Buildings

WWTP Aerial View (JPG)
Operations and Oxidation Ditch (JPG)
Headworks (JPG)
Biosolids Station (JPG)