Standard Operating Procedure - for the Analysis of Settleable Residue - Method: SM 2540 F-2020

Sep 2, 2026

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Standard Operating Procedure defines how to analyze settleable residue using Method SM 2540 F-2020. It specifies method applicability per regulatory definition, required sample volume (minimum 1 liter), container and storage conditions, holding time, and a controlled settling sequence in an Imhoff cone with defined stirring/spin steps. The procedure outlines apparatus, safety and waste handling expectations, documentation requirements for times and calculated residue volume in mL/L, and proficiency testing rules for blind PT samples within each PT calendar year.

LanguageEnglish

CategoryForms

FormatDOCX

Pages8

Reading Time3 min

AccessFree to download

Table of Contents

1.0 – Summary of Method

2.0 – Definitions

3.0 – Safety and Waste Handling

4.0 – Apparatus and Equipment

5.0 – Interferences

6.0 – Sample Collection, Preservation and Holding Time

7.0 – Procedure

8.0 – Documentation

9.0 – Proficiency Testing Procedures

10.0 – Reporting

11.0 – Employee Training

12.0 – References

13.0 – Revision History

Name of Facility Standard Operating Procedure for the Analysis of Settleable Residue Method: SM 2540 F-2020 Effective Date: Supervisor Signature: ___________________ Date:__________ Supervisor Name (print):________________________________ Table of Contents 1.0 – Summary of Method Pg. x 2.0 – Definitions Pg. x 3.0 – Safety and Waste Handling Pg. x 4.0 – Apparatus and Equipment Pg. x 5.0 – Interferences Pg. x 6.0 – Sample Collection, Preservation and Holding Time Pg. x 7.0 – Procedure Pg. x 8.0 – Documentation Pg. x 9.0 – Proficiency Testing Procedures Pg. x 10.0 – Reporting Pg. x 11.0 – Employee Training Pg. x 12.0 – References Pg. x 13.0 – Revision History Pg. x Blue text is replaceable instructional language to be customized for your facility. Summary of Method Settleable Residue is considered a method-defined parameter per the definition in the Code of Federal Regulations, Part 136.6, Section (a) (5). This means that the method may not be modified to reduce the sample volume per Section (b) (3). One liter of water is allowed to settle for 1 hour in an Imhoff Cone and the amount of residue which settles to the bottom of the cone is visually determined. State what type of samples are analyzed, e.g., wastewater effluent, ground water monitoring well, etc. State what the smallest gradation of the cone is, which will be the reporting limit Definitions mL/L: Units for the measurement of settleable residue. NC WW/GW LCB: North Carolina Wastewater Groundwater Laboratory Certification Branch Add any acronyms or terms used by your facility that may need to be defined Safety and Waste Handling Items that would be included in this section are things such as: Precautionary measures (list here and at the critical steps in the procedure) Personal protective equipment (e.g., gloves, eye protection, lab coat, work in a hood, etc.) Apparatus and Equipment Imhoff Cone Graduated cylinder Glass rod (remove if not using to stir) Timer (when used) Interferences N/A Sample Collection, Preservation and Holding Time A minimum of 1 liter is collected. State what type of container samples are collected in. Samples must be collected in glass, fluoropolymer or polyethylene containers. When sample analysis is not begun within 15 minutes, the sample must be transported and stored above freezing and ≤ 6°C. The holding time is 48 hours. Procedure Ensure the Imhoff Cone is dry prior to analysis. Mix the sample well and pour exactly 1 liter into the Imhoff Cone. Set timer and allow the sample to settle for 45 minutes. At 45 minutes, gently stir the sides of the cone with a glass rod (or) gently spin the cone (remove the procedure that is not done). Set timer and allow the sample to settle for an additional 15 minutes. Do not allow sample to settle for more than 1 hour total. Document the observed volume of residue in the bottom of the cone in mL. If the settled matter contains pockets of liquid between large settled particles, estimate volume of pockets of liquid and subtract from the volume of settled solids. NOTE: Where a separation of settleable and floating material occurs, do not estimate the floating material as settleable matter. Documentation All documentation errors shall be corrected by drawing a single line through the error so that the original entry remains legible. Entries shall not be obliterated by erasures or markings. Wite-Out®, correction tape, or similar products designed to obliterate documentation are not to be used; instead the correction shall be written adjacent to the error. The correction shall be initialed by the responsible individual and the date of change documented. All manual data and log entries shall be written in indelible ink. The following must be documented in indelible ink whenever sample analysis is performed. Date and time of sample collection Date and time of sample analysis (must document start and end times) to verify the 48-hour holding and the 1-hour settling times are met 45-minute stir time (use of

FAQs

What method acceptance constraints apply to modifying the settleable residue analysis?

Settleable Residue is treated as a method-defined parameter; the method may not be modified to reduce sample volume under the stated regulatory section (b)(3).

What are the required sample volume, settling time, and holding time?

A minimum of 1 liter is collected. Samples settle for 45 minutes, then an additional 15 minutes (total settling time must not exceed 1 hour). The holding time is 48 hours, with analysis time windows documented to verify holding and settling requirements.

How must the results and documentation be recorded during sample analysis?

Observed residue volume is documented in mL and reported in units of mL/L. Documentation must be completed in indelible ink with required dates/times, stirring checkbox (if used), facility name/permit or sample site, analyst identifiers, final reported value, method reference, and any applicable data qualifiers.

Sep 2, 2026

Upload by Eliana