Division of
Engineering & Roads

1026 W. Broadway Ave.
Spokane, WA 99260-0170
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Land Surveying

The Survey Section of the Spokane County Engineer's Office maintains a Continually Operating Reference Station (CORS) near the town of Latah in Washington State.

Latah, WA   Latah, WA

The station's antenna is mounted on top of three, one-inch stainless steel rods that have been arranged to resemble a "Tri-Pod".  One, additional vertical rod, positioned in the center, was added to mount to ensure the mount's stability.

As part of the requirements to become a certified CORS Site, the mount had to be anchored into “Bed Rock” Each leg, of the antenna mount, was set, into a drill hole, three feet into the rock and grouted (glued) into place. This bonding process enables Spokane Counties station to be used as part of the of Plate Tectonics study. An inspection of the drilling, setting and grouting the rods was completed and certified by the Pacific Northwest Geodetic Array (PANGA) located at Central Washington University, Ellensburg, WA.

Go to their web site below and you will see the movement of each Pacific Northwest monitoring site over the years. (Note:  Firefox needed to view the link below)

http://www.panga.cwu.edu/demo_vms/velo_map.html

A CORS station must be far more accurate than your hand held GPS receiver or your car's navigation system. Spokane County’s CORS, has an official data sheet listed with U.S. Geological Survey (USGS) and is called “LTAH CORS ARP, DI 3602”.  The station has a recorded position as follows:

     47 ° 16’ 56.72395” N 117 ° 09’ 49.92713” W ADJUSTED
     NAVD 88 754.185 (meters) 2474.36 (feet) ADJUSTED 

Spokane County’s CORS station also provides GPS Data to the Washington State Reference Network (WSRN). The WSRNis a regional cooperative of other GPS CORS stations. The combined data provides a cost-saving solution for both the public and private sectors. It is used in the Land Surveying, mapping, precision agricultural and other high accuracy location technology needs. The WSRN is an integral part of the modernization of the Spatial Reference System for Washington State as the “active control” component; working with state and federal agencies, scientific and academic communities, as well as the geospatial communities of surrounding states and provinces.

The technology used between the CORS stations and the WSRN allows surveyors to perform Real Time Kinematic work.  Advantages include easier documentation of section corners for property boundaries and accurate elevations to better determine the need for flood insurance and measurements for road and bridge construction.

USGS also uses the data provided by Spokane County's CORS Station. USGS uses utilizes the positional data for locating earthquakes and calculating their intensity. GPS is also used to includedata for generating mathematical models used to locate other GPS stations.

GPS involves orbiting satellites transmitting a signal to a receiver. A GPS receiver can determine location, speed, direction, and time. GPS receivers have become a very common navigation tool in today’s automobiles. http://www.trimble.com/gps_tutorial/

For more information about the Eastern Washington VRS Network, contact either of the County's Land Surveying Section.

Dave Berto dberto@spokanecounty.org
Jim McLeFresh: jmclefresh@spokanecounty.org

Spokane County is a member of
Washington Council of County Surveyors

The Washington Council of County Surveyors provides a one-page guide to consumers seeking to obtain a land boundary survey. The pamphlet provides guidance on selecting a land surveyor, contracts, professional services provided and much more.

To view or download the brochure, click here: Land Surveying - Questions and Answers