There are four methods of utility location that Underground Service Company utilizes with several client-selectable deliverable options. If the results of the survey are to be transposed to a construction document, a licensed land survey crew may be engaged after the location work is complete to record findings and produce a scaled exhibit. A standard survey prepared by Underground Service Company includes field markings on site with paint, feathers, flags or stakes.

Electro-magnetic Location - SUE Quality Level B

A signal is applied to a desired utility either directly or indirectly with a portable transmitter. An operator then sweeps the area with a receiver which enables tracking of the desired utility's course and depth without potholing. Some conditions known and unknown will affect the accuracy of the results. These conditions may include: soil conditions, foreign obstacles, utility congestion, and points of contact available to utilities. In addition a hand-held magnetometer is used to verify the presence of any metallic lines or structures below the area of concern. Non-metallic lines can not carry an electro-magnetic signal.

• Applications: Electrical, communication, oil/fuel, gas, metallic water lines, and some fiber-optic.
• Accuracy: If marked by the operator, the depth readings are accurate to +/- 10% of total depth from surface elevation. The lateral location is accurate to +/- 5% of total depth.
• Requirements: Optimum results are obtained when access is available to points of contact to the desired utility, i.e. manholes, pull boxes, valve stations, vaults, utility closets, etc.

Ground Penetrating Radar - SUE Quality Level B

In ideal conditions, ground penetrating radar is used to identify metallic and non-metallic utilities and structures as well as profiling their approximate depths. Some conditions known and unknown will affect the accuracy and effectiveness of the ground penetrating radar as a means of "clearing" an area. Dense clays or soils with high sodium content can mask the image of a desired utility.

• Applications: Metallic and non-metallic utilities and structures to a 30 foot depth (in ideal conditions).
• Accuracy: If marked by the operator, the depth readings are accurate to +/- 20% of total depth from surface elevation. The lateral location is accurate to +/- 10% of total depth.
• Requirements: Access must be available over the course of the desired utility.

Vacuum Excavation ("Potholing") - SUE Quality Level A

This method is ideal for projects where the exact location and elevation of known utilities is required. A "Vacmaster 4000" vacuum truck is mobilized along with a foreman and two operators.

The equipment uses air to excavate the road base, soil, even "½ sack" slurry for safe exposure of the desired utility without risk of damage to the line. This same technology is used by fire departments to rescue victims of trench collapses. The depth of the utility from existing grade is recorded and the hole is backfilled, compacted, and patched as required. When the desired utilities run beneath the public right of way, an encroachment permit, traffic control plan, and other requirements must be obtained and approved by the local authority. Underground Service Company can also provide a licensed land surveyor if the results are to be transposed to a construction document.

• Applications: Any type or size of utility up to 12 feet in depth. Special arrangements may be required for utilities deeper than 12 feet.
• Accuracy: Exposed utilities can be recorded exactly as to their lateral location and depth.
• Requirements: Approval from the local authority as required, general knowledge of what is to be located or prior mark out by the local one-call notification center if available.

Push Camera / Tractor Camera

A small camera with a built-in transmitter allows operators to follow the course of the desired utility from an entry point in the system through the route of the line. The camera head can be tracked above ground by an operator with a receiver that records the lateral position and elevation of the camera head. The maximum travel distance of the tractor-cam is 2,500 linear feet. The push-cam is limited to 300 feet of travel. Multiple changes in direction and some line conditions may adversely affect the distance capabilities.

• Applications: Storm drains, waste lines, empty ducts or conduit. (1" through 120" diameter).
• Accuracy: If marked by the operator, the depth readings are accurate to +/- 10% of total depth from surface elevation. The lateral location is accurate to +/- 5% of total depth.
• Requirements: Unrestricted access to manholes, catch basins, pipe inlets or clean-outs for equipment travel.