Laserfiche WebLink
<br /> City of Everett, Public Works Department, Water Pollution Control Facility <br /> <br />Page 3 of 13 <br />Introduction <br />The mission of the Everett Biosolids Management Program is to safely and beneficially reuse the <br />biosolids produced at the Everett Water Pollution Control Facility (WPCF). The Biosolids Management <br />Program also ensures optimal operation of the lagoon system for both biosolids and wastewater <br />treatment. <br />This document provides information on the WPCF’s plan for sampling and analysis of biosolids as <br />required under the Biosolids General Permit. <br />History <br />The WPCF was originally constructed in 1960 by the Snohomish County Health District and at the time <br />consisted only of an oxidation lagoon and an outfall into the Snohomish River. The City of Everett took <br />over operation of the facility in 1975 and has since made many improvements to the treatment process. <br />The Industrial Pretreatment Program, designed to mitigate pollutant loading from significant industrial <br />users, was approved in 1986. The trickling filter/solids contact system was built in 1991 and later <br />upgraded in 2014. The South Effluent Pump Station was added in 2005 to send discharge into the Port <br />Gardner Bay. Primary clarifiers were built in 2007, and the aerated lagoons were improved in 2010 to <br />enhance treatment. <br />As of 2024, the City of Everett sewer system serves approximately 115,000 people in the City of Everett <br />and 56,000 in nearby municipalities. <br />Solids Treatment Process <br />The WPCF operates a parallel treatment system consisting of the Trickling Filter/Solids Contact (TF/SC) <br />System and the Aerated/Facultative Lagoon System. The TF/SC System discharges treated effluent into <br />Port Gardner Bay, and the Lagoon System discharges treated effluent into the Snohomish River. These <br />two systems are connected through the Aeration Cells. <br />Solids must be removed from the wastewater stream in order to achieve acceptable effluent quality. <br />Inorganic material like rags and grit are removed by the Headworks to be ultimately landfilled. Floating <br />fats, oils, and grease removed by the Primary Clarifiers are landfilled. Settling sludge is removed by the <br />Primary Clarifiers and is pumped to the Aeration Cells for digestion. Settled solids from the Secondary <br />Clarifiers (microorganisms used for biological treatment) are also pumped to the Aeration Cells for <br />digestion. Solids from the Primary and Secondary Clarifiers can be strategically placed via several ports <br />around the perimeter of the Aeration Cells. <br />The Lagoon System in the order of hydraulic flow consists of the Aeration Cells, the Oxidation Pond, and <br />the Polishing Pond. Excess flows from the several areas in the TF/SC system can be diverted to the <br />Aeration Cells as a hydraulic buffer. The Aeration Cells consist of two 15-acre cells in series (AC1 and <br />AC2) which have mechanical aeration for odor control and treatment. Wastewater flows from AC2 to <br />the 130-acre Oxidation Pond, which is not mechanically aerated. Wastewater in the Oxidation Pond is <br />recirculated via the Recirculation Channel to improve treatment. Wastewater flows from the Oxidation <br />Pond to the 27-acre Polishing Pond and finally the Snohomish River outfall.