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RULE 4 PERFORMANCE STANDARDS <br />perimeter of each shall be recorded accordingly into one of five classes: perennial grass, perennial <br />forb, shrub, annual grass, or annual forb. Where possible recognizable taxa may be recorded by <br />species. Efforts with 1 — 2 perennial emergents per ft2 are considered to be fair, 2-3 perennial <br />emergents per ft2 are considered to be good, while 3-4 perennial emergents per ft2 are considered <br />very good. Five or more perennial emergents per ft2 are considered to be excellent. <br />Sample Adequacy Determination <br />Sampling within each monitored unit shall be conducted to a minimum of 5, 15 or 20 samples as <br />necessary. Sampling within each unit under consideration for bond release shall start with a <br />minimum of 15 (reference area) or 20 samples (revegetated area) and continue until a statistically <br />adequate sample (if necessary) has been obtained in accordance with Section 4.15.11 (2) (a). From <br />initial sampling efforts, sample means and standard deviations for total non -overlapping vegetation <br />ground cover, production, and woody plant density will be calculated. For bond release <br />applications, the typical procedure is that sampling continues until an adequate sample, nmin, has <br />been collected in accordance with the Cochran formula (below) for determining sample adequacy, <br />whereby the population is estimated to within 10% of the true mean (g) with 90% confidence. For <br />woody plant density, the estimate is to within 15% of the true mean. <br />When the inequality (nmin < n) is true, sampling is deemed adequate; and nmin is determined as <br />follows: <br />Nmin = (t2S2)1(d-X)2 <br />where: n = the number of actual samples collected (initial size = 15 or 20) <br />t2 = the value from the one -tailed t distribution for 90% confidence with n-1 <br />degrees of freedom (a value of approximately 1.3); <br />S2 = the variance of the estimate as calculated from the initial samples; <br />d = precision (0.10 for cover and production or 0.15 for woody plant density; <br />x = the mean of the estimate as calculated from the initial samples. <br />If the initial samples do not provide a suitable estimate of the mean (i.e., the inequality is false), <br />additional samples should be collected until the inequality (nmin < n) becomes true. However, <br />where sampling is for managerial (monitoring) information, adequacy is not necessary and is <br />calculated for informational purposes only. <br />If reverse -null testing will be utilized to document success, then in accordance with Rule 4.15.11 <br />(2) (c) a minimum of 30 samples must be collected and a demonstration of sample adequacy is not <br />necessary. In this circumstance a two -sample reverse null t-test is mandated along with <br />Satterthwaite approximated degrees of freedom and standard error. However, if an adequate <br />sample can be obtained from the reference area, then a less complex one -sample t-test may be <br />utilized. With the reverse null test, the smaller the variance (given by extra sampling) the better <br />the chances of passing closely matched parameters. <br />Rule 4 Performance Standards 4-80 Revision Date: 5/25/18 <br />Revision No.: RN -07 <br />