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<br /> <br /> <br /> <br />Page 1 of 4 <br />Standard Operating Procedure <br />WPCF Operations <br />Dewatered Biosolids Sampling SOP <br />Updated 2/21/2025 <br />A. Overview <br />The City of Everett stores residual solids from wastewater treatment in its wastewater lagoons, which <br />are dredged regularly to maintain treatment capacity. Biosolids are the dewatered product removed <br />from the lagoons and are a beneficial resource that can be used as a soil improvement provided that <br />regulatory requirements are met. <br /> <br />The purpose of this SOP is to standardize the sampling method of dewatered biosolids and ensure that <br />analyses are done in a repeatable and representative manner. Sampling methods must meet the <br />guidelines within the Statewide General Permit for Biosolids Management and Chapter 173-308 WAC. <br /> <br />B. Hazards & safety precautions <br />Biosolids are a wastewater product and, as such, pose potential hazards to human health. Caution <br />should be exercised when handling biosolids. Gloves and other PPE should be worn for the handling of <br />biological materials. Snowshoes and hip waders may be worn at the discretion of the sampling <br />operator. <br /> <br />Stockpiled biosolids are dewatered and can appear solid enough to support the weight of a person. <br />Due to the depth of the piles, the potential for entrapment exists wherever a portion of the biosolids <br />may be less dense than anticipated. Two persons should be present during all sampling activities. <br /> <br />C. Labor and Equipment <br />1. (1) Operations staff of any certification level <br />2. PPE (nitrile gloves, rubber boots, etc.) <br />3. (1) clean soil sampling probe (3-ft penetration depth) <br />4. (1) clean hand trowel, bucket mixer, or other tool to homogenize samples. <br />5. (1) clean hand brush to remove debris from sampling and mixing tools <br />6. Chain of Custody form <br />7. (12) labelled 8-ounce sample containers from the lab <br />8. Delineators to mark sampling areas <br />9. (7) clean 5-gallon buckets, labelled 1 through 7 <br />