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Table l : Sugg.ested sample dilutions Water source Dilutions (Sample Volume, mL Equipment, field blanks 100 Lakes, reservoirs, rivers 100, 50, 10 or 50, 10, 25 Wells, springs 100, 50, 10 or 100, 50, 25 Water supply intake 50, 10, 1 Natural bathing waters 50, 109 1 Sewage treatment plant 10, 1 , 0 . 1 Farm ponds, rivers 19 0 . 19 0 .01 Stormwater runoff 1 , 0 . 1 , 0 .01 Raw municipal sewage 0. 19 0 .01 , 0 .001 Feedlot runoff 0 . 11 0. 01 , 0 .001 Sewage sludge 0 .01 , 0 .001 , 0 .0001 4 . QUALITY CONTROL BLANKS a. The number and types of blanks to be run shall follow method requirements with these modifications : (i) If the membrane filter technique is used, the sample set(s) shall be associated with a beginning and ending filtration blank processed within a time period not to exceed 30 minutes . The environmental field samples shall be filtered after the beginning blank and before the ending blank. (ii) If filtration funnels are not sanitized by U light between samples, additional sterility blanks shall be filtered after every 10 samples processed within the 30-minute set b. The results of any blank must be < 1 CFU/ 100 mL or the associated sample results must be reported with the appropriate qualifier from Chapter 62460, F .A. C . ("V" for filtration blanks and "J" for field-generated blanks) . 5 . Laboratory Quality Control Duplicates a. At least 10% of the samples (or one per test run) shall be duplicated. b. All duplicate results shall be evaluated per method specifications using the precision criterion. The range of the transformed duplicates shall not exceed the precision criterion established by the laboratory. In the event that laboratory duplicate agreement is not observed, the laboratory must investigate the poor precision and report the results with appropriate qualifiers and/or comments. c . Field Quality Control Duplicates or Replicates - In the event that agreement (less than or equal the laboratory established precision criterion) is not observed between results from field-generated replicate samples, the laboratory must investigate the replicate analyses to determine that poor precision is not due to a laboratory error and report the results with appropriate qualifiers and/or comments . The laboratory shall use the analytical method specifications for precision control as a guide to evaluation of the field-generated replicate results. . 6 . Colony Counts a. In addition to the requirements listed below, all analytical results shall be calculated by the procedures established in the microbiological method(s) approved for the Contract and listed in the planning document. b. The laboratory shall make every attempt to ensure that colony counts are in the method-specified ideal range (20 — 60 colony forming units (CFU) for fecal coliform, enterococci and fecal streptococcus or 20 — 80 for total coliforms and E. coli). Reported values from colony plate counts outside this range shall be qualified with a "B" (unless the reported value is from a 100 mL sample and the count is less than 20). c . If all counts are above 60, the result shall be calculated and reported from the highest dilution. This result must be reported as "estimated" . 7 . Calculating Raw Data for Final Reporting - Standard Methods (SM) 9222D and EPA Method 1600 offer slightly differing guidance on the calculation and reporting of microbiological data. Although this guidance is not intended to capture every scenario possible in the calculation and reporting of the test data, the most common scenarios are discussed with the emphasis on reporting the data result, the dilution factor, and the data qualifier. For detailed discussions on additional scenarios, see the applicable method. REMAINDER OF PAGE INTENTIONALLY LEFT BLANK Revision Date: 02/09 DEP Agreement No. G0353, Attachment J, Page 10 of 14