Collection of Sludge Samples

Section 391 Section 391.502  Collection of Sludge Samples Collect samples during dry periods, and not sooner than 48 hours after the last precipitation.  Do not collect samples during freezing periods or sooner than 48 hours after a thaw.  Collect samples as follows: a)         Dried sludge:  Collect 100 grams of dried material or a core sample (whichever is greater) from each of 6 locations which include the perimeter and inner portions of the drying bed or lagoon, then composite these samples.  For mechnical dewatering facilities, collect 100 grams, 6-8 times at hourly intervals during a normal day's operating period and composite these samples. b)         Liquid sludge outside digester:  At each of 6 locations equally spaced along the perimeter of the storage area collect a core sample representing the top, middle, and bottom.  Composite the 6 samples and preserve according to USEPA procedures specified in "The Handbook for Sampling and Sample Preservation for Water and Wastewater," September 1982.  Analyses are to be carried out on properly preserved samples within the times specified. c)         Digester Contents:  If analyses are required on a quarterly or more frequent interval, samples for heavy metal analyses are to be collected weekly and composited.  If analyses are required on a semi-annual interval, three two-month composites are required each 6 months.  If analyses are required on an annual interval, three two-month composites are required; the first composite must be collected in the first 6 month interval.  One quart of each composited sample, preserved according to USEPA procedures described in subsection (b) above, shall be collected for the analyses. d)         Sample collection for all nitrogen analyses should be done immediately before analysis and preserved according to USEPA procedures described in subsection (b) above for water and sewage sludge samples.  Long-term composites are not acceptable.