Monument is typically a standard City of Gresham Control Monument, being a 2 inch bronze disk with raised datum point (Berntsen Model CD2LB), Stamped “City of Gresham Control Do Not Disturb”. Vertical: NGVD29 US Survey Feet GPS receivers are TOPCON HIPER+, static L1 L2 Vector reduction performed by TOPCON Tools Software, v 8 Least Squares adjustment performed by STAR*NET Software, v 7.1 Each control point was occupied for a minimum of one hour, on each of two different days. The values established on the points were constrained to a minimum of three City of Gresham primary control points.
The City of Gresham provides NO WARRANTY, expressed or implied, as to errors, omissions, suitability of purpose or positional accuracy, of City control monuments. Use of these monuments requires due diligence, by the professionals using the information; to insure the accuracy and appropriate use of the control.
The City of Gresham has developed a network of horizontal and vertical control monuments throughout the City to support surveying, engineering, construction, mapping, GIS and facilities management activities. Engineers, surveyors, planners and other consultants working on public improvements are required to georeference their work to the City of Gresham's vertical and horizontal datum. The horizontal datum is Oregon State Plane Coordinates, North Zone, being NAD83(91), in International Feet. The vertical datum is NGVD29, in US Survey Feet.
The monuments shown here have superseded all previous City of Gresham control monuments. The legacy monuments have been purported to be on the same datum but present considerable variation in origin, type, permanence and methodology. The new network has consistency in type, location and methodology.