Laserfiche WebLink
vegetation trampled by investigators during sample site location (Figure 1). It was deemed most prudent <br />to utilize this quadrat orientation and size to capture more variation "within the sample unit" and thereby <br />reduce "between sample" variation and hence sample size. To facilitate collection of production from a <br />full 1m quadrat, the first 1 /2 m frame was flipped end - over -end along the long axis following harvest of <br />the first frame. This process resulted in a sampling unit of 0.5 meters X 2.0 meters. From within each <br />quadrat, all above ground current annual vegetation within the vertical boundaries of the frame were <br />clipped and bagged separately by life form as follows: <br />Perennial Grass Perennial Forb <br />Annual Grass Annual Forb <br />Sub - shrubs <br />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 Adeauacv Determination <br />Sampling within each managerial unit was conducted to a minimum of 24 or 25 (cover and woody <br />plant density) and 48 or 50 (production) samples per unit. Sampling within each reference area was <br />conducted to a minimum of 15 (cover) and 45 (production) samples per area. From these preliminary <br />efforts, sample means and standard deviations for total non - overlapping vegetation ground cover, <br />production, and woody plant density (informational only) were calculated. For bond - release applications, <br />the typical procedure is that sampling must continue until an adequate sample, n has been collected <br />in accordance with the Cochran formula (below) for determining sample adequacy, whereby the <br />population is estimated to within 10% of the true mean (p) with 90% confidence. Otherwise, reverse - <br />null evaluations must occur. <br />follows: <br />When the inequality (n <_ n) is true, sampling is deemed adequate; and n is determined as <br />where: n = the number of actual samples collected (initial size = 15, 25, etc.) <br />t = the value from the one - tailed t distribution for 90% confidence with n -1 <br />degrees of freedom; <br />s 2 = 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. <br />nmin = (t / (0.1 .4' ) <br />Page 8 Hamilton Mine - 2011 <br />Phase III Bond Release Evaluation <br />