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2.4 Determination of Current Annual Production <br />At each sample site, current annual production was collected from a 1 / 2 m quadrat frame placed <br />one meter and 90 to the right (clockwise) of the ground cover transect to facilitate avoidance of <br />vegetation trampled by investigators during sample site location (Figure 1). To facilitate collection of a <br />full 1M production, the first frame was flipped (along the long axis) resulting in a sampling unit of 0.5 m <br />X 2.0 m. From within each quadrat, all above ground current annual vegetation within the vertical <br />boundaries of the frame were clipped and bagged separately by life form as follows: <br />Perennial Grass Perennial Forb Sub shrubs <br />Annual Grass Annual Forb Noxious Weeds (if found) <br />All production samples were returned to the lab for drying and weighing. Drying was conducted at 105° C <br />until a stable weight was achieved (24 hours). Samples were then re- weighed to the nearest 0.1 gram. <br />2.5 Sample Adeguacv Determination <br />Sampling within each managerial unit was conducted to a minimum of 25 (cover and woody plant <br />density) or 50 (production) samples per unit. Sampling within each reference area was conducted to a <br />minimum of 15 (cover) and 45 (production) samples per area. From these preliminary efforts, sample <br />means and standard deviations for total non - overlapping vegetation ground cover, production, and <br />woody plant density (informational only) were calculated. For bond - release applications, the typical <br />procedure is that sampling must continue until an adequate sample, n has been collected in <br />accordance with the Cochran formula (below) for determining sample adequacy, whereby the population <br />is estimated to within 10% of the true mean (u) with 90% confidence. Otherwise, reverse -null <br />evaluations must occur. <br />When the inequality (n <_ n) is true, sampling is deemed adequate; and n is determined as <br />follows: <br />nmin = (t2s2) / (0.1 .� )2 <br />where: n = the number of actual samples collected (initial size = 15, 25, 45 or 50) <br />t = the value from the one - tailed t distribution for 90% confidence with n -1 <br />degrees of freedom; <br />S2 = the variance of the estimate as calculated from the initial samples; <br />7 = the mean of the estimate as calculated from the initial samples. <br />CEDAR CREEK ASSOCIATES, Inc. Page 6 Hamilton Mine - Phase III Bond Release <br />Year 1 of 2 <br />