We are excited to share our expertise and demonstrate how RETTEW’s geophysics services can help you minimize project delays and change orders and reduce liability. We’ll also highlight some of our people so you can be sure you are getting the best in the business when you work with RETTEW.

Find the Dam Leak!

Unaddressed seeps or defects in dams can lead to unexpected catastrophe, like the 1889 Johnstown Flood following failure of the South Fork Dam on the south fork of the Little Conemaugh River. Fortunately, geophysics can safely—and non-intrusively—detect or characterize dam seepage and other problems to avoid these types of disasters. For example:

  • Spontaneous Potential Surveys help detect movement of water through the dam; microgravity detects mass-deficient areas (subsurface washouts, voids, or zones where fines have been flushed)
  • Electrical Resistivity Imaging or Electromagnetics detect water-saturated areas
  • Ground Penetrating Radar can map locations and the extent of shallow voids beneath concrete spillways, and the rebar pattern in the concrete.

Using geophysics to evaluate dam integrity is a critical tool for preventing dam failure.

Want to hear a cool story about a leaky dam? Click here to read all about it!

Meet Chris Lash


Chris has been doing geophysics throughout the United States for almost 20 years. At RETTEW, he specializes in subsurface utility engineering, which involves mapping subsurface utilities and structures at all kinds of facilities. And when he’s not being a geophysicist, he’s a firefighter for the State of Maryland. Needless to say, he’s fighting fire with fire in both jobs!

Chris loves using science at RETTEW and as a firefighter every day to solve different kinds of problems. He thinks of them as puzzles because he finds every challenge to be fun. He is passionate about both careers and gets a thrill helping people using the unique skill sets he has developed from each specialty. As a result, he never feels like he is at work—he is just always doing what he loves. When Chris is not working, though, you can usually find him outdoors hiking, hunting, fishing/crabbing, or traveling to brilliant places.