A site survey is a report on specific conditions of a site. This report generally requires position control, which may be either geodetic (Lat/Long, Universal Transverse Mercator (UTM), State Plane,...) or local (X-Y, Range/Bearing). Examples of specific conditions and information to be gathered include:
- Sand waves
• Geology and Geophysics:
- Bottom material
- Subbottom strata
- Engineering properties
- Kelp or coral beds
- Rock outcrops
- Ice scour
- Military mines, tank traps, and other military submerged facilities
- Seafloor installations (well heads...)
- Cables and pipelines
- Fishing grounds
- Anchorage areas
Typical site surveys include the following:
• Bathymétrie surveys are conducted to select routes for cables and pipelines and to determine locations for shallow water arrays. As an example, they are specifically used to chart the route of the Offshore Petroleum Discharge System (OPDS) pipeline.
• Visual surveys of selected cable and pipeline routes are required to locate obstructions and damage to the cable or pipeline. A visual survey is especially important for installation of the OPDS SALM buoy to locate all potential bottom obstructions.
• Geophysical and geotechnical surveys are required to determine the characteristics of the seafloor material along a cable or pipeline route, or in the vicinity of a new mooring or structure. Geo technical surveys are required in advance of Elevated Causeway (ELCAS) installations for site selection and to determine requirements for pile driving.
• Construction surveys are required to establish locations for the installation of new facilities or document the as-built location of existing facilities.
• The establishment of survey control points is a special case which extends existing control points to the survey area.
Surveys requiring divers are usually limited to water depths of less than 120 feet, while bathymétrie and geophysical surveys in water depths greater than 200 feet are usually outside the tasking of the UCTs. ROVs could supplement diver surveys in deeper waters or hazardous conditions.
The following sections discuss the preliminary planning requirements for a site survey (Section 4.2), typical procedures for conducting survey operations and equipment used (Sections 4.3 and 4.4), and methods of presenting the results (Section 4.S). These descriptions are general in nature, and the requirements of any particular survey may vary from those discussed.
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