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PART I <br />Page 8 of 22 <br />Permit No.: CO-0001244 <br />Data from 11 pm to 12:59 am, would fall in the previous day. Data collected from 11:01 pm to 1:00 am would fall in the new <br />month. <br />8. "Dissolved (D) metals fraction" is defined in the Basic Standards and Methodologies for Surface Water 1002-31, as that <br />portion of a water and suspended sediment sample which passed through a 0.40 or 0.45 UM (micron) membrane filter. <br />Determinations of "dissolved" constituents are made using the filtrate. This may include some very small (colloidal) <br />suspended particles which passed through the membrane filter as well as the amount of substance present in true chemical <br />solution. <br />9. "Geometric mean" for fecal coliform and E. coli bacteria concentrations, the thirty (30) day and seven (7) day averages shall <br />be determined as the geometric mean of all samples collected in a thirty (30) day period and the geometric mean of all <br />samples taken in a seven (7) consecutive day period respectively. The geometric mean may be calculated using two different <br />methods. For the methods shown, a, b, c, d, etc. are individual sample results, and n is the total number of samples. <br />Method 1: <br />(Un) <br />Geometric Mean = (a*b*c*d*...) means multiply <br />Method 2: <br />Geometric Mean = antilog ( [log(a)+log(b)+log(c)+log(d)+...]/n ) <br />Graphical methods, even though they may also employ the use of logarithms, may introduce significant error and may not be <br />used. <br />In calculating the geometric mean, for those individual sample results that are reported by the analytical laboratory to be "less <br />than" a numeric value, a value of 1 should be used in the calculations. If all individual analytical results for the month are <br />reported to be less than numeric values, then report "less than" the largest of those numeric values on the monthly DMR. <br />Otherwise, report the calculated value. <br />For any individual analytical result of "too numerous to count" (TNTC), that analysis shall be considered to be invalid and <br />another sample shall be promptly collected for analysis. If another sample cannot be collected within the same sampling <br />period for which the invalid sample was collected (during the same month if monthly sampling is required, during the same <br />week if weekly sampling is required, etc.), then the following procedures apply: <br />i. A minimum of two samples shall be collected for coliform analysis within the next sampling period. <br />ii. If the sampling frequency is monthly or less frequent: For the period with the invalid sample results, leave the spaces <br />on the corresponding DMR for reporting coliform results empty and attach to the DMR a letter noting that a result of <br />TNTC was obtained for that period, and explain why another sample for that period had not been collected. <br />If the sampling frequency is more frequent than monthly:, Eliminate the result of TNTC from any further calculations, and use <br />all the other results obtained within that month for reporting purposes. Attach a letter noting that a result of TNTC was <br />obtained, and list all individual analytical results and corresponding sampling dates for that month. <br />10. "Grab" sample, is a single "dip and take" sample so as to be representative of the parameter being monitored. <br />11. "In-situ" measurement is defined as a single reading, observation or measurement taken in the field at the point of discharge. <br />12. "Instantaneous" measurement is a single reading, observation, or measurement performed on site using existing monitoring <br />facilities. <br />13. "Maximum Weekly Average Temperature (MWAT)" is defined in the Basic Standards and Methodologies for Surface Water <br />1002-31, as an implementation statistic that is calculated from field monitoring data. The MWAT is calculated as the largest <br />mathematical mean of multiple, equally spaced, daily temperatures over a seven-day consecutive period, with a minimum of <br />three data points spaced equally through the day. For lakes and reservoirs, the MWAT is assumed to be equivalent to the <br />maximum WAT from at least three profiles distributed throughout the growing season (generally July-September).