_INSPECTION - C1981010 (66) - Laserfiche WebLink

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In order to determine compliance with approximate original contours for SL-11, elevations of points collected in the field with a GPS unit were compared to elevations provided in the SL11 Bond Release application. Using ArcGIS, 20 locations were selected from the SL-11 Bond Release map and downloaded into a Trimble GeoXT GPS unit. The points were selected at approximately equal distances apart and generally at 50-foot elevation intervals, to represent the entire SL-11 Bond Release area. The figures below indicate the locations for F-AB-08 and Z-A-08, some of which are outside of the parcel boundaries and were used for reference. (Points in E-AB-08 are not shown, as there is a significant issue with this area as discussed below in the"Slides and Damage" section.) During the bond release inspection, inspectors navigated to the points using data in the Trimble unit, and another point was collected with the Trimble unit. The points collected at the site were downloaded from the Trimble into Pathfinder Office and converted into a point shapefile to utilize in ArcGIS. Elevation data using the Trimble GeoXT is not exact. The Geoid used in the Trimble GeoXT is DMA 10X10 Global, which is a global elevation Geoid and not as accurate as a localized Geoid. For this reason, a point was collected at the Trapper Mine base station (on the office roof)to determine a correction factor for the elevation collected in the Trimble GeoXT. The elevation at the base station was 6513 feet above sea level compared to 6527 feet on the Trimble, which indicated the need for a correction of plus 14 feet. The main purpose of the elevation collection was to determine if the elevation data showed any anomalies, such as drastic elevation changes or fluctuations in elevation. All elevation points were found to be between 13 feet and 19 feet above the elevations of the approved Approximate Original Contour(AOC). Given the correction factor of plus 14 feet at the Trapper Mine base station, the difference in elevation is not significant, and the backfilling and grading of the SL-11 areas is consistent with the contours submitted with the SL-11 application and the approved AOC. Elevation Points in F-AB-08 and Z-A-08 Elevation Points in Z-A-08 Topsoil Topsoil had been previously measured in the F-AB-08 parcels and the E-AB-08 parcels and found to meet the permit requirement of a minimum of 10 inches. During the inspection, topsoil in the Z-A-08 parcels was measured with a shovel and tape measure, and all areas were found to meet the 10-inch minimum depth.