BUILDING STRONG®04/22/2023

Working Partnership

USACE working closely with NOAA (NGS, Office of Coast Survey, and CO-OPS)►Assistance in Developing Guidance►Training and Workshops►Certification Program►Tools for Connection to NSRS (OPUS-DB,

VDATUM)►Updating Projects

BUILDING STRONG®04/22/2023

USACE Requirements Relate all projects to NSRS

► Policy in place► Nominal Accuracy Requirements: Hor: 2’, Vert: 0.25’ (relative to

the NSRS, local relative accuracy most likely higher)► All projects have dual elevations: Water Level and Geodetic► Tidal benchmarks tied to NSRS

Need to have published values for NSRS Control► Transformation to current and past values

• Conversion tools a must► OPUS DB essential and OPUS Projects desired

Built Project Control Database► Manage local project control (rely on NGS for connections to

NSRS) Need performance based standards (not just

specifications and procedures)

BUILDING STRONG®04/22/2023

Continued Challenges

Areas of Subsidence and Uplift► Vertical time dependent positioning???

Implementing standards► Establishing Geodetic and Water Level references

Education► Critical to making sure datums are understood

Tidal areas (new datum related to tidal gages) Real Time Networks (connected to NSRS)

BUILDING STRONG®04/22/2023

Guidance Development

Relate all to a Single Nationwide

Reference System (i.e. NSRS)

Developed EC 1110-2-6065/70 (Jul 07) to provide interim guidance on evaluating project datums.

Developed ER 1110-2-8160 on Policy for referencing project elevation grades to nationwide vertical datums

Draft EM 1110-2-6056 on Standards and procedures for referencing project elevation grades to nationwide vertical datums

Draft

BUILDING STRONG®04/22/2023

NSRS ControlProject Primary ControlProject Local Control

THE HISTORIC OR LEGACY REFERENCE NETWORK

WILL NOT CHANGE OR BE ELIMINATED. THIS

PROCESS JUST RELATES YOUR NETWORK TO THE

NATIONAL SPATIAL REFERENCE SYSTEM

This tie is easily accomplished with GPS and

OPUS-DB