Projects on the water present unique challenges to professional engineers, scientists, planners, and contractors. Thew Associates has extensive experience working in marine environments providing seamless topographic and utility mapping from upland surveys through transition zones and into deeper water. Working under the direction of a Certified Hydrographer, the Thew Associates hydrographic survey group has the requisite equipment and expertise to undertake a wide range of water based projects.

Hydrographic Services

  • Centimeter horizontal and vertical accuracies
  • Sample layout and location
  • Sampling vessel navigation
  • Vibracore and gravity core sample collection
  • Sub-bottom profiling
  • Chemical and geotechnical analysis (subcontracted)
  • Side Scan Sonar and Snippets
  • Seafloor imagery and classification
  • Object detection
  • Full Water Column
  • Identify and characterize seafloor strata
  • Buried object detection
  • Benthic habitat characterization
  • Magnetic object detection
  • Identifies submerged cables and pipelines
  • Archeological features
  • Velocity and Current Studies
  • Construction and remediation design data
  • Flow rate and direction determination
  • Hydraulic modeling support
  • Wave Height Studies And Monitoring
  • Single- and multi-beam acoustic data collection
  • Slope monitoring
  • Dredge support services
    1. Pre- and post-dredge surface topography
    2. As-built surface topography
    3. Dredge volume calculations

Mark R. Williams, CH, PLS

Mark R. Williams, CH, PLS



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