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r <br /> Mac <br /> CIWMB/CIA Section <br /> (916) 341-6722 <br /> From: Patrick Lehrmann [mailto:plehrmann@southwestgeophysics.com] <br /> Sent: Thursday, September 16, 2004 5:12 PM <br /> To: Martinez-Centeno, Abel; Owen, Dawn; Macanas, John; Young, Glenn <br /> Subject: Sting Resistivity Survey for Landfill Delineation <br /> Hi Guys, <br /> Hans van de Vrugt and I just started our own geophysical firm called <br /> Southwest Geophysics. We are still working closely with Ninyo & Moore, <br /> however, this gives us the freedom to focus on strictly geophysics. I just <br /> wanted to let you know the news, and send you our latest technical email. <br /> Hope you are all doing well. Is Glen back in the States? <br /> Cheers, <br /> Patrick <br /> Recently, we were asked to conduct a high resolution resistivity survey to <br /> determine depth to bottom of fill and landfill areas at a huge Brownfield <br /> project in Arizona. Profiles were conducted at areas of suspected debris <br /> landfills and areas of uncompacted fills to compliment proposed <br /> environmental and geotechnical drill sites. The native formation at the <br /> site was an electrically resistive conglomerate. <br /> This profile was conducted as a baseline study, since historical records <br /> indicated that it had not been disturbed. <br /> As you can see, there is a fairly shallow layer of fill (five feet) over <br /> the more resistive native. <br /> This profile was conducted in an area of suspected buried trash. As you can <br /> see, large bull's-eye areas of high conductivity exist. <br /> These areas are interpreted to be metal and other conductive land fill <br /> debris and are up to depths of more than 16 meters. <br /> This profile was conducted along a river bank in an area where a cut bank <br /> was reportedly filled, but not compacted. <br /> As it turned out, the fill was more conductive then the native soil and the <br /> cut bank is easy to recognize. <br /> This profile was conducted in an area of suspected concrete and rock <br /> debris. As you can see, large Bull's-eye areas of higher resistivity exist. <br /> These areas are interpreted to be buried concrete and decorative boulders <br /> and extend to depths of up to 20 meters. <br /> Some benefits to consider: <br /> This survey work was conducted despite ongoing operations at the <br /> several properties. <br /> These surveys can be conducted in endangered habitat sensitive areas. <br /> No permitting is required for conducting these surveys, and <br /> therefore, can be scheduled ahead of drilling. <br /> 2 <br />