[Mark Harrison]

Range poles with an optical prism: Start with either a sheet of grid paper or an aerial photo with a card table on the site. Tape paper onto foam core board. Tape board onto card table. If using an aerial, get it from a professional aerial survey mapping company, not Google Earth. Call the city planner if you can’t find a source. Find two reference points that are distinctly visible on the aerial at approximately the same land elevation and create a base line between them, both on site and on the aerial/grid paper. Set up two range poles (or vertical poles of some sort) and lay out a tape measure(s) between them. Visually align the base line between the two poles by sighting it from either end. Have a buddy stand on the site feature to which you’re measuring with a third range pole. Using an optical prism, direct your buddy left and right while you site him/her with the prism. The optical prism allows you to site your buddy at exactly 90 degrees perpendicular to the base line. Note the base line station and then measure from that station to your buddy. This will give you your “x” and “y” values for the site feature. Scale and draw the site features on the grid and/or verify their “x” and “y” coordinates on the aerial. I would “note only” x and y coordinates on an aerial and verify locations back in the office. As for shooting grades, I believe there is no substitue for a level of some sort and a surveying rod. Shoot grades at cross-sections along sations on the base line and perpendicular to it. Measure feet left and feet right using a tape or the surveying rod. Be sure to measure to, and shoot grades of, grade breaks, high points, low points, etc.  One great advantage of doing your own site measuring in this way is that YOU actually touch every site feature yourself, and “crap, I didn’t know that was there” will rarely happen. As with all of the other blog responders, I would recommend having a licensed surveyor prepare a survey and base map before going to CDs. Perhaps the above method will allow you to “zero in” on which areas need to be surveyed by the surveyor, depending on the extent of your utimate design. One note:  Even if you obtain a sie survey from a professional aerial survey mapping company, don’t depend on contours. Always field verify (at least spot check) grades before going to CDs. 

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