Benchmark Network Datum

The City of Newberg Benchmark Network historically consisted of brass caps set in curbs with elevations established through traditional methods in the NGVD 29 datum. Today, the City runs a Continously Operating GPS Reference Station (CORS), which provides elevations in the NAVD 88 datum as based on GEOID03. In Newberg, NGVD 29 elevations are generally around 3 1/2 feet lower than NAVD 88 elevations.  

Coordinate System

The City of Newberg uses the State Plane Coordinate System of 1983, Oregon North Zone 3601, as defined by ORS 93.330(1)(c), with coordinates reported in international feet and conforming to the (CORS 96)(EPOCH 2002) adjustment. 

Monument Density and Accuracy

Most of the original brass caps, as well as many other monuments found in the public right-of-way, have been measured using GPS. Measurements have been made on over 600 monuments across the City. The accuracy of the GPS elevations is plus or minus 2 cm and the monuments are located horizontally with State Plane Coordinates to within plus or minus 1 cm.