Survey and Design

The Global Positioning System (GPS) surveying equipment utilized by Ducks Unlimited to collect field data, stakeout projects, perform check-outs and collect as-built data is an invaluable tool to accomplishing our mission. Conventional surveying methods could be used to perform the same task, but would require additional personnel; making them cost prohibitive.

GPS surveying can provide an incredibly accurate “picture” or topographic map of the landscape at a fraction of the time that it would take to generate the same data with traditional surveying equipment. This is due to the extended range of the GPS, and its use of satellite communication to gather and store data as opposed to traditional equipment that requires an unobstructed line-of-sight and has a more limited range.

The heart of the GPS surveying unit is the “base”, that is calibrated to a permanent point or location established by the technician on the initial site visit. The base point will be utilized as the main “control point” for future data collection and by contractors during construction. The two GPS antennae provide radio and satellite communications from the base to the individual backpack units used to either gather data or provide stakeout for the contractors.

The majority of “ground” and “boundary” shots can be taken from an ATV equipped with a customized rack that allows data collection over a very large area. Certain shots, such as Tempory Benchmarks or unique features such as flow lines of existing culverts or areas inaccessible by an ATV, can be accomplished manually. The technician removes the satellite antenna from the ATV rack and places it atop the GPS pole, adjusts the antenna height in the data collector, and then collects the required data. These manual shots can also be used to provide a higher degree of accuracy as a result of the receiver being stationary for a longer period of time.

After the initial site survey is completed, the data are downloaded into the computer to be utilized in the wetland design. An engineer generates a design of the wetland using computer aided drafting software (i.e., AutoCAD). From the GPS data, the engineer can compute excavation and embankment volumes and develop blueprint drawings of the project.

Prior to wetland construction, the GPS is once again used to stakeout the project as designed. The design data are downloaded into the data collector, the base is setup and initialized on the same permanent reference point, and the rover is remounted on the ATV rack. Key points and elevations (i.e., levees, ponds, sloughs, water control structures, etc) are marked with wooden stakes, flagging tape, and paint for future reference by the contractor during construction.