GRADE CONTROL CAPABILITY OF A PULL BEHIND DRAINAGE PLOW

In September 2001 at the Don Scott Air Field, Columbus, Ohio, forty-four experimental mock subsurface drainage installations were executed using a Liebrecht drainage plow, laser transmitters, GeoStar GPS system, and a John Deere 9400 tractor. The focus of the study was to evaluate the grade control capability of the Liebrecht pull-behind drainage plow under experimental conditions and to develop a testing method for similar drainage plows. The GeoStar GPS system was used to estimate the tubing boot outlet elevation during long field runs that were structured to test for speed, depth of operation, grade change and crossing an extreme land slope change. The data were analyzed to determine if the average standard deviation of the plow's tubing boot outlet elevation met the installation criteria set forth by ASTM 449-02 and other past standards, although there were several individual deviations that exceeded these standards. Through the complex interaction of speed, depth, grade changes and direction of slope, the drainage plow's grade control capability was influenced but no direct link could be made to any one factor.