oh my....it let me log in this morning....
tmk....if you have a relatively flat area to test, a small rig running hollow stem augers would get you more test holes in a shorter period of time than any other method. the purpose of the hollow stem auger is to allow a sampling device (usu. a split spoon) to be run through the augers and tehn driven w/ a hammer to collect undisturbed soil ahead of the bit. these soil samples can then be evaluated in the field and/or sent to a lab for geotech analysis......grain sizes, soil type, permeability, etc...in most deep soil areas (i.e. no bedrock present) a small hollow stem auger rig could easily go over 100 feet deep, so depth is not an issue. you could compare costs easily against a backoe by simply contacting local environmental or geotechnical drilling companies, telling them what you want, and have them bid.
in my experience, relatively shallow holes (<30 feet) should go around 10 to 20 per foot, maybe cheaper if the drillers can just backfill w/ drilled out soil and dont have to plug each hole w/ cement. plus lab costs if you send samples to geotech lab. total price could be a couple to several thousand dollars depending on how many test holes you do, but it would be the best possible information you could ever want and the investment might well be worth it if you want a nice pond that holds water for many years to come IMO.
good luck
