Ground Penetrating Radar Systems was recently contracted to complete a site investigation for subsurface utilities prior to renovation of a fast food restaurant in downtown Washington D.C.
GPRS was tasked with locating and marking all the underground utilities within a scan area of about 3,000 square feet. The client intended to drill soil borings at 10 individual locations upon completion of our investigation. The client also requested keeping an eye out for potential underground storage tanks whose existence could not be confirmed by prior owners of the property. Technologies used during the site investigation included the GSSI Utility Scan with a 400 MHz antenna, as well as the Vivax EM Pipe Locator.
During the investigation, the Arlington, Virginia-based Project Manager located a variety of subsurface utilities passing through the designated scan area. These utilities included electrical conduits, site lighting conduits, communications conduits, multiple gas lines, and one sewer line. The approximate orientation, direction, and depth of each underground anomaly was marked using spray paint in the corresponding colors outlined by the 811 uniform color code.
These utilities were found using multiple avenues of investigation. The electrical and communications conduits moving from the building towards the generators were located using the GSSI Utility Scan’s ground penetrating radar. The Project Manager utilized the device in 2-foot grid patterns across the property to identify both subsurface utility lines as well as identify any potential underground storage tanks per the client’s request. The sewer line was also located using this method.
Meanwhile, the gas lines were located by direct connection- inducing an electrical tone through the exposed section of the pipe (above ground)- and tracing the tone with the Vivax EM Pipe Locator wand. This same strategy was used to locate the site lighting circling the property. Once these marks were traced with the EM wand, their accuracy were then confirmed using GPR.
Additional electric lines were located with the EM wand’s Live Power reader, and then confirmed with GPR.
After completion of the utility locate portion of the investigation, the Project Manager began clearing 5ftx5ft individual areas for soil borings to be drilled. These cleared areas were marked with white spray-painted brackets and numbered to indicate to the client which exact locations were cleared for drilling.
Following the utility locate, a non-survey grade GPS file was created using a Geode GPS mapping device. This file was provided to the client for future reference on potential projects at this location.
If you would like a similar project completed or want to learn more about the technologies that GPRS uses on its projects, reach out to your local GPRS representative by visiting our contact us page.
GPRS does not provide geophysical, geological, land surveying or engineering services. If you need such services, please contact an appropriate professional.