Water Well Journal
Issue link: http://read.dmtmag.com/i/668983
cent development allowing the landscape and boundaries of the dig area or drill site to be viewed remotely through high- resolution aerial imagery (PAPA 2010). Utility Locating Techniques As was mentioned, underground utilities can be found by looking at existing utility owner records or, when needed, using a utility locating service. The source of information and methods used to locate underground utilities could impact the reliability and accuracy of identifying and locating under- ground lines. In addition to power lines, there are phone lines, gas lines, water lines, and sewer lines running underground. Different detection techniques need to be used for different types of buried lines. For instance, detection of metal cables and pipes can be done using electromagnetic devices consisting of a transmitter and a receiver. Radiolocation devices use radio waves to find a location and are used for detecting non-ferrous lines (plastic or concrete). Since there are different types of materials used in under- ground utilities, not all types can be detected using conven- tional methods. Non-conventional utility locating techniques include acoustic locating, ground penetrating radar (GPR), and magnetic locators or metal detectors. GPR detection is an electromagnetic method often used to enhance other locating techniques. It can generate 3D under- ground images of pipes, power lines, sewer lines, and water mains. Magnetic locators or metal detectors and magnetometers are often used to locate buried metal objects other than pipes. An acoustic locator most often detects and traces nonmetal water lines and can also be used in identifying the locations of plastic gas lines. Current utility locating technology cannot assure 100% de- tection of every underground utility line and pipe. There are limitations with each utility locating technique, which must be considered. Understanding Locating and Marking Practices Operator markings of utilities include the appropriate color for the type of facility, their company identifier (name, ini- tials, abbreviation) when other companies are using the same color, the number and width of their installations, and a description of the underground utility. A combination of paint and flags are used to identify the operator's installations at or near an excavation or drill site. Color code identifiers are summarized in Table 1. Refer to the CGA's Best Practices 12.0 (2015) for more specific guidelines for locating and marking practices. Additional Warning Signs When an excavator arrives at a job site after contacting the local one-call center to get the job site located, the first step is to look for signs of underground utilities. These signs should be obvious—look for marking flags, paint, pedestals, fire hydrants, and other above-ground indicators. Even though these indicators may signal there are no un- derground utilities within the dig area or drill site, be alert to additional warning signs as you start the excavation. If you see any visual signs of a buried utility while excavating or drilling, stop immediately and hand dig until the utility is exposed. Contact the utility owner as necessary and do not proceed until the utility is fully exposed and identified. Conclusions Excavators and drilling contractors should come up with a detailed work plan: Train employees on the proper procedures for determining the locations of underground utilities. Contact and coordinate with the local one-call agency and utility companies to establish locations of underground installations. Take necessary precautions to prevent damaging underground utility installations. SAFETY from page 48 DACUM Codes To help meet your professional needs, this column covers skills and competencies found in DACUM charts for drillers and pump installers. DO refers to the drilling chart and PI represents the pumps chart. The letter and number immediately following is the skill on the chart covered by the column. This column covers: DOA-4; DOC-9, 11, 12; DOK-8, 9; DOL-1, 3; PIB-1, 2, 5, 7, 9; PIE-5; PIG-3 More information on DACUM and the charts are available at www.NGWA.org. Figure 1. Root cause categories for damages to underground utilities (CGA 2014). waterwelljournal.com 50 May 2016 WWJ