Laserfiche WebLink
I. <br />Kleinfelder <br />December 10, 2003 <br />Page 2 <br />SURVEY PROCEDURES <br />Horizontal Control <br />Prior to data acquisition, we established a horizontal control survey grid over the site using a <br />fiberglass measuring tape. The survey grid was based on a rectangular coordinate system. Grid <br />points were marked on the ground surface with spray paint and used to orient our GPR traverses and <br />ensure complete coverage of the prescribed survey area. <br />Methodology <br />Based on site conditions, we performed the investigation using two different geophysical methods: <br />Electromagnetic Metal Detection (MD), and Ground Penetrating Radar (GPR). Detailed descriptions <br />of these geophysical methods including the associated instrumentation and limitations can be found <br />in Appendix A. The general survey procedures for each method are outlined below. <br />111 Electromagnetic Metal Detection <br />Initially, we conducted the MD survey to delineate buried metal objects, including potential USTs <br />or pipes. We hand-carried the metal detector along traverses spaced five feet apart in both north- <br />south and east-west orientations. The locations of detected features were marked out with spray <br />paint. The steel-reinforcing in the concrete precluded the use of the MD method within <br />approximately 5 feet of the apron. <br />Ground Penetrating Radar <br />Following the MD scanning, we used the GPR method to cover the area on a five foot grid. We <br />conducted both east-west and north-south traverses as shown on Plate 1. Additional traverses were <br />performed as necessary over suspect areas identified on the primary profiles. We examined the <br />resulting GPR records for reflection patterns that might potentially represent USTs, utilities, or other <br />localized subsurface objects.