09-01-2006, 07:13 PM
Haven't work on void detection for a long time, but had some experience in hiring the service back in the '90's. It was in the thousands for either a GPR or an EMI test of older gas stations (for remediation work). Usally more than 10x the survey cost, and this was on fairly level terrain. The technician must cover all of the mapped terrain with an antennea detector (vehicle mounted or pull behind are the most common). Think of how much it would cost to have a trained (most likely flown in) technician walking across the terrain, if it could even done on some of the lots here.
GPR units are coming down into the $20-25,000 range for a pull behind unit, but I cannot imagine how it would be possible on many of the lots here, prior to clearing. Most of the lots are cleared by D-9s, so they end up being a void checker. It does seem that the operators are all well aware of void potentials here. I think that a lot more would have to get pitted more often to justify the cost of a vehicle mounted array that would work well on the terrain here.
Aloha, Carey
GPR units are coming down into the $20-25,000 range for a pull behind unit, but I cannot imagine how it would be possible on many of the lots here, prior to clearing. Most of the lots are cleared by D-9s, so they end up being a void checker. It does seem that the operators are all well aware of void potentials here. I think that a lot more would have to get pitted more often to justify the cost of a vehicle mounted array that would work well on the terrain here.
Aloha, Carey