Jerry's Benchmark Worksheet

MEASURED August 2007NAD83/98 from VRS Stations Spokane, Latah, Koot, & Grouse CreekTwo 30 minute observations with a different satellite constellation were used for controlling benches.Two 3 minute observations with a different satellite constellation were used for FEMA Benches.GEOID 03 was used to convert HAE to NAVD 88Corpscon 6.0.1 (Vertcon) was used to convert from NAVD 88 to NGVD 29NGVD 29 datum is the 1947 adjustment.Offsets were used when actual bench could not be occupied by GPS.Measured Values Published Data Vertcon Converted VERTCON DifferenceName North East NAVD 88 Description NAVD 88 NGVD 29 NAVD 88 NGVD 29 NGVD 29 NGVD 29 Published tofrom from from to NAVD 88 measuredPublished Published Measured1st Order NGS BenchesA 71 268404.448 2447096.158 2252.427 BRASS CAP 2252.41 2248.558 2248.575 3.852 -0.017C 265 369547.322 2472467.641 2195.678 BRASS CAP 2195.75 2191.843 2191.771 3.907 0.072D 485 278355.538 2481917.716 2069.424 BRASS CAP 2069.45 2065.654 2065.628 3.796 0.026H 265 307567.747 2494511.268 1897.752 BRASS CAP 1897.94 1894.128 1893.94 3.812 0.188M 35 210239.497 2540711.637 2593.66 BRASS CAP 2593.63 2589.749 2589.779 3.881 -0.03S 506 247766.797 2476639.428 1809.37 STEEL ROD 1809.38 1805.584 1805.574 3.796 0.01Y 70 251158.78 2425560.843 2421.944 BRASS CAP 2421.94 2418.042 2418.046 3.898 -0.0043rd Order NGS Benches19WS1948 Offset 304151.926 2461329.491 1593.54 SPIKE ACROSS ROAD19WS1948 correction 0.32 1593.86 Brass Cap (destroyed) 1590 ...