The boundaries and locations of each disposal unit shall be accurately located and mapped by means of a land survey. Disposal units shall be marked so that the boundaries of each unit can be easily defined. Three permanent survey marker control points, referenced to United States Geological Survey (USGS) or National Geodetic Survey (NGS) survey control stations, shall be established on the site to facilitate surveys. The USGS or NGS control stations shall provide horizontal and vertical controls as checked against USGS or NGS record files.
25 Pa. Code § 236.412