Safety 1st Advancer Manual del operador descargar pdf (Pagina 27)

Environmental Remediation Drilling

Safety Guidelines

Page 27 of 132

• In all cases, it is preferable to clear a hole to about 120% of the diameter of the largest tool used for

drilling, so as not to miss structures that might be just slightly tangential to the borehole. For

instance, if a 10-inch hollow stem auger is being used to drill, a cleared area 12 inches in diameter

should be used. The cutting head is often the largest diameter tool used for drilling and the cleared

footprint should be 20% larger than the cutting head.

• When angle drilling, clearance should consider 120% of borehole length, along with the utility

window profile. If possible, it is recommended to at least clear intended areas where the drill string

will enter and exit the ground, and to use any means possible to positively identify the location and

depth of any utilities that will be crossed in the boring process. The same vertical and horizontal

considerations described for the vertical drilling should be used for angled or horizontal drilling.

2. In addition to completing all locates and completing clearance of subsurface locations along the path of

the drilling head, additional excavations can be completed as described below:

• If possible, excavate small areas to visually monitor the drill bit. A buried drill bit makes it

impossible to tell a utility has been struck. Verify the drill bit remains at least 5 feet away from the

utility. Keep the hole open until the drill bit has been pulled back and the drilling is complete.

• Carefully excavate to expose utilities so the drill bit path can be monitored.

3. Calibrate the drill bit and locating device at the beginning of the project. Remember, the locating device

can monitor the drill bit on the initial pass, but cannot monitor the backream head.

4. Workers should stay at least 5 feet (to 10 feet if space is available) away when boring parallel to buried

utilities. Carefully excavate to expose utilities so the drill bit path can be monitored.

2.11 - Clearance Methodologies

Before drilling within 10 feet of an underground utility, the utility depth must be verified. Flags and locator

marks indicate the direction the utility is running, but not how deeply it is buried. The only way to be sure of

utility depth is to carefully expose and examine the utility line.

Clearance methodologies can be broken into two major categories:

• Those that can involve direct contact in order to reveal a subsurface structure, and

• Those that attempt to avoid the contact.

Direct contact is not universally acceptable. The following methods should be pursued only by experienced

personnel. Proper hand-digging tools and techniques will protect both the workers and the utility.

• A blunt-nosed shovel is used to loosen the soil and a regular shovel is used to remove the soil. A pickax

or a pointed spade should never be used. Do not stab at the soil or stomp on the shovel with both feet.

• Work with a gentle prying action and dig at an angle, so the shovel will slide along the surface of the

wire, conduit, or pipe. Or, dig to the depth the utility is expected to be, but off to the side. Then, use a

prying motion to break away soil as you approach the utility laterally.

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Safety 1st Advancer Manual del operador Pagina 27