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          be expected. If the area has been subjected to large landslides, trees,
          and other natural or manmade objects may have been buried and
          could be encountered. If the area has been subjected to low-energy
          streams and rivers, then fine-grained deposits may be expected. Con-
          versely, high-energy, steeply sloped stream beds may be covered with
          cobbles and boulders from nearby mountains. Reports on surface
          contours and elevations are also important so that any possible
          ground movements, settlements, and heaves can be monitored. Dur-
          ing the design and bidding phase of the project, it may be necessary
          for engineers and contractors to visit the project site and visualize the
          degree of job difficulty that may be encountered during the project
          execution.

          9.2.2 Subsurface Investigations
          Subsurface investigation is the next step to surface survey. Subsur-
          face features, which will impact trenchless installations, include
          presence of existing underground pipelines and utilities or other
          manmade structures, and method of their placement. Geotechnical
          conditions, such as existence of solid rock, heavy gravelly soil, and
          boulders and cobbles along the alignment of proposed trenchless
          installation must also be investigated.

          Locating Existing Utilities
          Trenchless installation projects require the contractor to install the
          pipe without seeing the excavation area. Therefore, the design
          engineers should give contractors a record of potential conflicts and
          utility crossings.
             In the United States, the local one-call service like MISS DIG in
          the state of Michigan or the national number 811 should be contacted
          as a first step prior to design and construction of a trenchless project.
          In other countries, and in the absence of one-call service, municipali-
          ties and utility companies should be contacted individually to obtain
          the required information. Obtaining as-built and record drawings,
          geographic information system (GIS) data, utility maps, and locating
          pipeline markers are also important. Geophysical methods subsur-
          face utility locating may include surface-applied pipe locators,
          ground-penetrating radar (GPR), electrical resistivity imaging, and
          seismic survey. In addition to the information provided by design
          engineers (usually in terms of soil-boring logs and possibly soil
          reports), and contacting utility companies and one-call centers, con-
          tractors must positively locate and expose existing utilities running
          parallel less than 10 ft (at specified intervals, such as every 50 ft,
          dependent on proximity and type of existing utility and trenchless
          method used) or where it proposed trenchless alignment crosses
          an  existing utility or pipeline. Exposing utilities can be done by
          mechanical equipment (such as a backhoe), hand shoveling, and/or
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