Laserfiche WebLink
extraction, although not necessazily involving land where material is actually being removed. Also indicated <br />is the acreage of the pazcel. For stockpiles an estimated volume is shown. <br />These maps were produced using a handheld GPS. Each zone was walked around and landmazks <br />taken at numerous points. Those landmazks were then converted to map coordinates and the outlines <br />created on the maps. Key, well identified landmazks (e.g. section comers) were measured and compazed to <br />the actual latitude and longitude of those landmarks. By comparing the readings of the GPS unit with <br />actual locations an error factor was derived for the handheld GPS unit. As a rule, handheld GPS units aze <br />quite accurate although not precise. Errors of up to 10 meters (about 30 feet) can occur with respect to <br />individual readings, although usually the reading is more accurate than that if the unit is allowed to average <br />readings of a location for 30 seconds to one minute. The average errors found in the known landmarks was <br />about 18 feet with a range of about 8 feet to 26 feet. Furthermore when a landmark reading of an unknown <br />location is faz out of range it usually become quite apparent when the landmazk is mapped relative to other <br />landmarks. None of the neazly 300 GPS readings taken showed any obvious misalignment relative to <br />adjacent readings, so the error factor was reasonably constant and not evident at the scale of the mapping. <br />Nevertheless, the average error at the scale of the map is about 3% of the true value. That is, the <br />boundaries identified on the maps are within 3% of the tme location. <br />Elevations of landmarks were taken, but were not used because it is well known that handheld GPS <br />units are least accurate with respect to elevation with common elevation erzors in excess of 100 feet. <br />Examination of the elevation data demonstrated that, in contrast to the location data, it was unreliable and <br />showed considerable inconsistency. This is consistent with expectations from a handheld GPS unit - <br />accurate location but unreliable elevation measurements. <br />Disturbances Identified: <br />Table 1 presents a summary of each of the disturbance locations found and identified on the maps. <br />These are divided into two large groups. The lowland group refers to the South Lowland azea (Map 1). The <br />upland group refers to the Upland Area (Maps 2a and 2b). Shown in the table is the identifier label (M, R, <br />or W followed by a number), the acreage of that unit, and a description of what the unit includes. <br />Table 2, which immediately follows Table 1, shows the breakdown of the units included in Table 1. <br />This breakdown divides all of the land included into various categories. With regard to the reclamation <br />units, the breakdown distinguishes land that is ready or possibly ready for release from land that is clearly <br />not ready for release. This technical revision does not contain any request for release of bond for any of this <br />land even though it identifies land that will be requested for release in the near future. <br />Page 2 of 8 <br />