1. Dam Seepage/ Subsidence Geophysical Survey

    An old earthen dam displayed signs of seepage. One state agency wanted to breach and rebuild it immediately, and another agency wanted to repair it. RETTEW was tasked with detecting areas of seepage, soil piping, or erosion of materials beneath the dam. Site conditions were grassy embankments, a concrete spillway, and suspected sheet piles from…

  2. Residential Comprehensive Sinkhole Survey

    An engineer was investigating whether a homeowner’s insurance policy would cover damages to their property due to a sinkhole. To provide confident detection of potential subsurface features and properties associated with the sinkholes, RETTEW applied several complementary geophysical techniques. We used microgravity mapping to detect and delineate soil cavities or zones of low-density soils. We…

  3. Churchyard Cemetery Mapping

    A church was concerned that its walled cemetery excluded some very old unmarked graves, likely containing wooden caskets, given their age. To resolve this uncertainty, RETTEW conducted a ground penetrating radar (GPR) survey to detect any anomalies that might represent unmarked burials. RETTEW scanned the areas just outside the cemetery boundary walls with a digital…

  4. Bedrock Depth Mapping at a Solar Farm

    A solar farm was expanding onto a hill where a limestone rock outcrop was observed. This raised concerns about shallow rock that could impede installation of the driven rods that support the solar panels. In soil, the rods need to reach a specified depth to prevent wind from lifting the panels. If the rock is…

  5. Crosshole Geophysical Tomography for a Tunneling Project

    RETTEW’s Geophysics team recently assisted a client with a tunneling project. The tunnel path was at a depth at which surface geophysics could not resolve potential small zones of concern, including low-stiffness weathered rock that might require special support, and water-bearing seams that could flood the opening. The required resolution could only be achieved using…

  6. Sunoco Service Station Mise à la Masse Survey

    Gasoline that spills on a pervious surface or leaks from an underground storage tank will infiltrate downward until it encounters the groundwater table. Since gasoline is less dense than water, it floats as a light non-aqueous phase liquid (LNAPL) plume. In a boring at an active service station, our client encountered floating gasoline, which caused…

  7. Critical Care Facility Seismic Hazard Analysis

    Earthquake-resistant construction is expensive, especially in a place like the New York metropolitan area. A health care client was looking for the most cost-effective design for a critical care facility while incorporating the appropriate degree of earthquake resistance. In seismically active areas, including the NY metro area, there is a tendency to overconstruct. This is…

  8. Geophysical Hydrographic Survey for Dam Fish Ladder Construction

    A hydroelectric plant on a major river sought to install a new fish ladder for an endangered species. Construction of the ladder required founding the concrete walls directly on bedrock. However, because of years of sedimentation above and below the dam, the thickness of the sediment and bedrock conditions were unknown. RETTEW was hired to…

  9. Geophysical Borehole Logging for Landfill Monitoring Well Placement

    A growing landfill required constant monitoring along its periphery to ensure aging liners and containment systems were functioning as designed. New monitoring wells were needed in key locations at proposed expansion points. The geologically complex area required in-depth analysis of migration flow paths to effectively site the monitoring wells. Using borehole geophysics, we detailed planar-feature…

  10. Roadway Void Detection Survey

    Our client experienced poor surface drainage and subsidence along a roadway in central Pennsylvania. These occurrences made road conditions dangerous. RETTEW/Enviroscan’s geophysics team surveyed the terrain to locate the source of the problem. The unique site conditions of this project required a combination of geophysical techniques to determine the proper solution. We performed four different…

RETTEW NEWSROOM

Check out our latest updates on industry trends, corporate news, employee accomplishments, and community support.

Go to Newsroom

Uncategorized

RETTEW Charitable Foundation Awards Grant for What If 101 School Program

The RETTEW Charitable Foundation awarded a $5,000 grant to TomTod Ideas for What If 101, a weekly program…

Read More

Awards

RETTEW’s Elizabeth Helsel Recognized as 2022 Top Solar Designer

RETTEW is pleased to announce Elizabeth Helsel, Design-Build Project Manager, has been recognized as the 2022 Top Solar…

Read More