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105 <br /> 1 small depressions within the ground. 1 variety of different sets of -- pairs of electrodes <br /> 2 Q. Okay. 2 through the ground. <br /> 3 A. And then we do identify the 3 C,cripleting this procedure, it <br /> 4 approximate location of the -- of the air shaft. We 4 develops a mapping of the two-dimensional plane. <br /> 5 did -- 15 Q. Okay. And would you tell us what <br /> 6 Q. Okay. And this is the air shaft you 6 areas, based on the alignment shown in Figure 2, you <br /> 7 heard Mr. Boulay and Mr. Stark discuss earlier? 7 would anticipate it capturing data? <br /> 8 A. Yes. 8 A. Essentially the way this works, <br /> 9 Q. Okay. All right. ft don't we go 9 you -- the data cross section is higher in the near <br /> 10 ahead and discuss the application technique. What 10 surface and then it kind of tapers down. So it's a <br /> 11 sort of, I guess, electrode systems were utilized? 11 big — not quite a triangle, but parallelogram that <br /> 12 A. Yeah. This system is an industry 12 tapers and bates (sic) off, and the depth that you <br /> 13 standard system for electrical resistivity 13 look is proportional to the separation of the <br /> 14 tomography. It was manufactured AGI USA, and 14 electrodes on the surface. <br /> 15 it's -- this particular system was an 84-channel, 15 Q. lCy the -- what is labeled as L-1 off <br /> 16 which means you can read 84 different electrodes in 16 to the west of the rest of the lines? <br /> 17 the ground. I think it's called the R8. ( 17 A. We tried to get something we thought <br /> 18 And it is designed to do electrical 18 may have been out of the area of influence of <br /> 19 resistivity tomography, where you can generate large 19 the vertical migration of the groundwater. So, you <br /> 20 amounts of data, multiple data points in a 20 know, a background of -- you know, you made — we <br /> 21 two-dimensional plane through the ground, is what 21 wanted to see something where we thought, you know, <br /> 22 it's designed for. And it allows you to do this in 22 there was little or no influence of vertical <br /> 23 an efficient manner and collect both near-surface 23 structure in the area. <br /> 24 and -- data that correlates with the parameters with 24 Q. Okay. Was the site prepared in any <br /> 25 depth. 25 way in anticipation of this ERT study? <br /> 105 107 <br /> 1 Q. All right. 1 A. Yes, there was. In order to <br /> 2 A. The same thing. 2 increase, again -- the presence of water decreases <br /> 3 Q. Using Figure 2, could you please 3 the resistivity of the units within the subsurface, <br /> 4 ascribe for the Board haw the system was arrayed? 4 and since that's what we were looking for was trying <br /> 5 A. Yes. We -- in this survey every 3 5 to identify areas where groundwater may flow, before <br /> 6 meters we put an electrode in the ground. The 6 we arrived on-site, I think this survey was 10,000 <br /> 7 electrode consists of a stainless steel spike, and 7 gallons of water was put into the ditch. <br /> 8 it is put into the ground, and it varied. Most of 8 Q. Okay. How was the data your <br /> 9 them were -- 84 electrodes were put. 9 technicians collected in April of 2016 processed and <br /> 10 I think they had a couple of to interpreted? <br /> 11 then they were a few electrodes short due to 11 A. Yeah. We -- there's a program called <br /> 12 logistic considerations, but generally all of those 12 REZ2DINV. That's an industry standard program for <br /> 13 were put in the ground. 13 the evaluation of earth -- or electrical resistivity <br /> 14 And to increase the electrical 14 tomography data, but it's used, like I said, <br /> 15 conductivity to allow us to get more current into 15 throughout the industry. We have a license to use <br /> 16 the subsurface, we wetted each of the electrodes, 16 that. <br /> 17 which, again, the — the moisture in there decreases 17 We use that to input the data into <br /> 18 resistivity, allows more electricity to go into the 18 the program, and we converted the raw data to a form <br /> 19 ground, increases our signal. 19 that the program would accept. We went through the <br /> 20 Q. Okay. 20 data; identified certain data points that were law <br /> 21 A. Then we went -- to continue, we then 21 quality due to, you know, low signal strength or a <br /> 22 activated the system, and it goes through a series 22 variety of other reasons. <br /> 23 of current injections into the ground through two of 23 We removed those from the data set, <br /> 24 those electrodes, and then it reads the potential 24 and then there's an automated inversion program <br /> 25 difference -- the voltage difference between a 25 that -- inversion routine that the program runs, and <br /> 106 108 <br />