5.3. SR 02-10-2003 - Laserfiche WebLink

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split samples that were tested by MVTL is provided on Table 4 in Appendix B. Copies of MVTL's analytical reports are contained in Appendix C. The split-sample data indicates var/ability in the samples results. Relative percent differences (RPD) ranged from 29% to 162%. Presumably, this is not atypical for fecal samples because of the potential lack of uniformity of the sample resulting in potential uneven distribution of waste matter in the sample matrix. Th.is lack of uniformity can be ~rther compounded by split sampling (dividing or splitting a sample for analysis by two or more laboratories) and laboratory preparation and analyses procedures. Fecal matter also has a relatively short life-span so natural decay can also effect results. Overall, the split results continued concentrations of fecal coliform above the 200 CFU/100 ml standard. 3.6 FECAL STREPTOCOCCI DATA On behalf of the City, Liesch requested MVTL to test for fecal streptococci in an attempt to differentiate between human or animal waste origin. Copies of their analytical reports are contained in Appendix C and the results area summarized on Table 5 in Appendix B. Fecal coliform (FC) / fecal streptococci (FS) ratio's greater than 4.0 were once considered indicative of human fecal contamination, whereas a ratio less than 0.7 was suggestive of Contamination by' non-human sources. For various reasons, including survival rates of fecal streptococci group species, the FC/FS ratio assessment has a high false-positive rate and therefore should not be used as the sole means of differentiating between human and non-human sources of pollution (Appendix D). Although this ratio is no longer relied upon in and of itself, it could provide a general means of potentially identifying primary waste type. However, the abnormally high precipitation associated with the sampling period allows for greater mixing of waste types that may enter surface waters. This should be taken into consideration when evaluating the data. . Overall, the results of the testing were inconclusive. Generally, FC/FS ratio's were higher at Station 16 (Big Elk Lake Outlet) and lowest at Station 27 (downstream of feedlot) and at the Orono Beach. This data is suggestive of animal waste impacts near the feedlot and beach. 3.7 MISCELLANEOUS INFORMATION / DATA Other information provided to Liesch for review included the following: City of Elk River Memorandum dated September 4, 2002 - Information provided in the memorandum indicated that on August 5, 2002 City of Elk River and Sherbume County Environmental personnel investigated a complaint fi-om the Sherbume County SWCD concerning possible fecal coliform bacteria contamination of the Elk River from feedlots LIESCH ASSOCIATES, INC. Hydrogeologists · Engineers · Environmental Scientists · Page 5 · · Jan-2003 ·