2021-11-22-minutes-public-works-study-session

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KITTITAS COUNTY DEPARTMENT OF PUBLIC WORKS PUBLIC WORKS — BOARD OF COUNTY COMMISSIONERS STUDY SESSION STAFF REPORT STUDY SESSION DATE: November 22, 2021 TOPIC: New Datums Replacing NAVD 88 and NAD 83 ACTION REQUESTED: Support Staff Efforts LEAD STAFF: Mark R. Cook RECOMMENDATION: Complete updating National Geodetic Survey monuments to the maximum extent possible before year's end. BRIEFING SUMMARY: • The National Geodetic Survey is switching the nation's datums and reference system in 2022. • For the past eleven months, County Surveyor Turnbull and his team have been updating NGS monument data countywide. • In the state of Washington, Kittitas County and Yakima County lead the state in the monument revisiting effort. • A large GIS effort is needed responding to pending changes in the nation's datum and geospatial reference systems. • Once this round of NGS updating is complete, all of the past five years of Public Works monument data updating will tie back making improvements to the County's tax parcel layer possible. BACKGROUND: To improve the National Spatial Reference System (NSRS), NGS will replace all three North American Datum of 1983 (NAD 83) frames and all vertical datums, including the North American Vertical Datum of 1988 (NAVD 88), with foie- new terrestrial reference frames and a geopotential datum. The new reference frames will rely primarily on Global Navigation Satellite Systems (GNSS), such as the Global Positioning System (GPS), as well as on a gravimetric geoid model resulting from our Gravity for the Redefinition of the American Vertical Datum (GRAY -D) Project. These new reference frames will be easier to access and to maintain than the current NSRS, which relies on physical survey .marks that deteriorate over time. Page 1 of 4 Public Works "Work Session Staff Report", 2021