The Lake Agassiz Water Authority Pipeline is being designed to transport water from the Missouri River basin 120 miles east to the Red River Valley.  AE2S was hired to establish primary control, provide LiDAR mapping control, and perform quality control surveys on the LiDAR mapping deliverables.

Primary control was established by placing highly stable geodetic control monuments spaced approximately every five miles along the 120-mile route.  The monuments are required to hold positional stability for a minimum of 10 years so that they may serve as base station locations through construction and as-built mapping of the pipeline.  The monuments were constructed of a ¾ inch stainless steel smooth bar driven to refusal.  The bar was enclosed in an aluminum assembly for protection and easy access by surveyors and contractors.

 AE2S surveyors established high-precision coordinates on the monuments by collecting GPS readings for three hours on each.  The GPS observation data was uploaded to the National Geodetic Survey’s Online Positioning User Service (OPUS).   OPUS provides the most accurate available coordinate solution by utilizing the most current geoid models.  AE2S provided the owner with a manual that contained descriptions and values for the monuments along with maps showing their location.

AE2S also set targets for aerial photography and surveyed their locations to help with the geo-processing of digital ortho-photos of the route.  With coordinates provided by the surveys, raw photographs are transformed into accurate geo-referenced photography to be used for design and as-built mapping.

Digital terrain mapping was also needed for the design portion of the pipeline.  The terrain mapping was obtained by Laser Imaging Detection and Ranging (LIDAR).  The LIDAR process requires GPS ground control to be accurate.  AE2S surveyors worked closely with the airborne crews to complete the LIDAR mapping process.

One the mapping is complete, it must be checked for accuracy as a quality control measure.  AE2S surveyors performed ground GPS surveys in the mapped area.  GPS coordinate values from the survey were compared to the mapping.  AE2S surveyors and GIS specialists then provided a report of the owner with the accuracy results for the mapping product.