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Avoiding Utility Relocations
Appendix B: Best Practices
Plat Designation of Existing Underground Facility Easements
Practice Statement: Plats involving development of real property include the designation of underground facility easements.
Practice Description: Various items are required on the plats filed prior to the development of lands. Where plats are required to be filed, the items required include the identification of the easements of underground facilities traversing the land described on the plat. Identification of easements of underground facilities on the plat increases notice to developers and the public about the existence of the underground facilities. Notification to the owners of underground facilities that a plat has been filed alerts underground facility owners/operators to establish communication between the developers and the operators to facilitate a plan and design for the use of the land which complements the underground facility.
Example of Practice: St. Louis County surveyors in Minnesota require that plats show easements of underground facilities. Conditional use permits are required to develop gravel pits in St. Louis County, Minnesota, and a prerequisite to the permit being issued is the notification to the owners of underground facilities that a permit to develop the gravel pit in the vicinity of their facilities has been sought.
Benefits: Often underground facility owners/operators do not receive notice of developments impacting their facilities until excavation activity has commenced. This compromises the optimal use of the land and potentially compromises the integrity of the underground facility.
St. Louis County, Minnesota zoning ordinances.
Gathering Information for Design Purposes
Practice Statement: The designer uses all reasonable means of obtaining information about underground facilities in the area of the planned excavation.
Practice Description: During the planning phase of the project, all available information is gathered from facility owners/operators. This includes maps of existing, abandoned and out-of-service facilities, cathodic protection and grounding systems, as-builts of facilities in the area if the maps are not current, proposed project designs, and schedules of other work in the area. This information is gathered for the purpose of route selection and preliminary neighborhood impacts, and as part of the process of impact analysis when evaluating different design possibilities.
Methods of gathering information may include contacting a one-call center, facility owners/operators, coordinating committees/councils, other designers, engineering societies, and governmental agencies as a means of identifying underground facility owners/operators in an excavation area. Gathering information may also include a review of the site for above ground indications of underground facilities (i.e., permanent signs or markers, manhole covers, vent pipes, pad mounted devices, riser poles, power and communication pedestals and valve covers). The one-call center provides a listing of operators directly to the designer, or to the designer's subsurface utility engineer. This information is available in formats that are accessible to all users such as voice, fax, e-mail or web-site. Once identified, the designer contacts the operators directly or use the one-call system. The facility owner/operator may locate their underground facilities or provide locations of their underground facilities to the designer by other means, such as by marking up design drawings or providing facility records to the designer.
Examples of Practice:
As a minimum, the designer responsible for the preparation of plans and specifications for an excavation obtains information on underground facilities within and near the project area. Some states, such as Wisconsin, Pennsylvania and Minnesota have statutes requiring such designers to contact one-call centers within a set time frame to obtain facility information. Where the information obtained suggests facilities may conflict with the excavation, an underground facility survey or subsurface utility engineering is used.
Designers often utilize an underground facility survey process to minimize conflicts with existing underground facilities. The underground facility survey process employed in New York, NY, by Consolidated Edison and other utilities has several distinct steps. Each of the steps is performed in order, but any higher step may be omitted, depending on the proposed construction and the locations of existing underground facilities discovered in the next lower step.
Underground Facility Survey Steps Include:
Use company records and contact other facility owners/operators to obtain information about locations of existing underground facilities. This step includes the entire construction/excavation area.
Using the information obtained in the first step, visit the job site to correlate the information gathered about existing underground facilities with above ground features. This step may be limited to those portions of the construction area where existing facilities are present and where excavation is to occur.
Use appropriate instruments or other methods to determine the approximate horizontal locations of the underground facilities identified in the second step. This step may be limited to specific areas where existing facilities are expected to conflict with excavation.
Use test holes to positively determine the exact location of existing underground facilities. At this point, horizontal and vertical control measurements may be taken of the underground facility. This step is usually limited to those specific areas where conflicts are anticipated between existing facilities and proposed construction activities or proposed facilities, or where elevation information is essential to design the proposed facility.
Test holes are used to positively locate and identify an underground facility by exposing the facility by a nondestructive means of excavation. Such nondestructive means can be by hand, vacuum truck, air knife, etc.
Test holes may be requested under the following conditions:
- the design calls for a grade change,
- facility records indicate that proposed underground facilities or excavation may be in close proximity of existing underground facilities,
- elevations of proposed sewers or drains may interfere with existing underground facilities where required to determined potential geometry changes for water main installations,
- to locate points where proposed underground facilities may be tied into existing underground facilities, and
- to determine environmental conditions in an excavation area.
Test hole data includes at a minimum:
- date performed and purpose;
- type of existing surface and base of roadway or sidewalk and depth of each;
- general soil conditions found;
- any indication of oil or waste materials found in the pit; and
- facility cover, size, configuration, elevations (if applicable), and distance from curbs or other horizontal control.
- SUE is performed by, or under the direction of a registered professional engineer. SUE includes up to four quality levels for gathering underground facility information, to be specified by the project owner to be part of the project planning and design process. The Federal Highway Administration (FHWA) advocates its use and many State Department of Transportations, such as but not limited to Virginia, North Carolina, Maryland, Texas, Ohio, Florida, Washington, and Delaware, use this process.
Subsurface Utility Engineering Quality Levels are:
Quality Level D information comes solely from existing utility records. It may provide an overall "feel" of the congestion of utilities, but it is often highly limited in terms of comprehensiveness and accuracy. Its usefulness should be confined to project planning and route selection activities.
Quality Level C involves surveying visible above ground facilities such as manholes, valve boxes, poles, pedestals, pad-mounted devices, etc., and correlating this information with facility records obtained in Level D. When using this information, it is not unusual to find that many facilities have been omitted from records or erroneously plotted. Its usefulness should be confined to locations where facilities are not prevalent or are not expensive to repair or relocate.
Quality Level B involves the use of surface geophysical techniques to determine the existence and horizontal position of facilities, including those identified in Level C. This activity is called designating. Two-dimensional mapping information is obtained. This information is usually sufficient for excavation planning. Decisions can be made on where to place structures or new facilities to avoid conflicts with existing facilities. Slight adjustments in the design can produce substantial cost savings by eliminating facility relocations.
Quality Level A involves the use of nondestructive excavation devices at critical locations to determine the precise horizontal and vertical position of existing facilities, as well as the type, size, condition, material, and other characteristics. This activity is called "locating." When surveyed and mapped, precise plan and profile information is available for use in making final design decisions. Additional information such as facility material, condition, size, soil contamination and paving thickness also assists the designer and facility owner/operator in their decisions.
Caution: Both the underground facility survey process and Subsurface Utility Engineering (SUE), as described above, may include marking the ground surface to indicate the approximate location of existing underground facilities. Both processes are tools to be used in project design. They should not be confused with underground facility locating (and marking) that is performed in response to a request, usually by an excavator, to a one-call center, immediately prior to beginning excavation work, as described elsewhere in this Report.
Some one-call centers accept calls for design purposes but the locating usually provided in response to such calls should be enhanced as described in this section to be adequate for project design purposes. Such locating, however, may be adequate when planning smaller excavations and less extensive work where excavations can easily be adjusted to avoid marked facilities with appropriate clearances. Such less extensive work might include utility pole replacements, roadside ditch cleaning, smaller homeowner excavations or residential fence posts.
Benefits: Gathering underground facility information and including this information in the planning phase minimizes the hazards, cost and work to produce the final project.
- Safety is enhanced.
- Unexpected conflicts with facilities are eliminated.
- Facility relocations are minimized.
- Wisconsin Sec. 186.075 Stats.
- Minnesota Statute 216D.
- Pennsylvania Act 287 of 1974, as amended by Act 187 of 1996.
- See related Finding Number 3, "Identifying Existing Facilities in Planning and Design."
- "Construction Management Interference Control Manual," Consolidated Edison, New York, New York, June 9, 1997.
- Subsurface Utility Engineering, Federal Highway Administration (FHWA), February 1999, Office of Program Administration (HIPA).
- Florida Department of Transportation Utility Accommodation Manual, Document No.: 710-020-001-d, Section 11.4, January 1999.
Identifying Existing Facilities in Planning and Design
Practice Statement: Designers indicate existing underground facilities on drawings during planning and design.
Practice Description: During the planning phase of the project, existing facilities are shown on preliminary design plans. The planning documents include possible routes for the project together with known underground facility information. The various facility owners/operators are then given the opportunity to provide appropriate feedback.
During the design phase of the project, underground facility information from the planning phase is shown on the plans. If information was gathered from field located facilities, from underground facility surveys or from subsurface utility engineering, this is noted on the plans. If an elevation was determined during the information gathering, it is shown on the plan. The facilities shown include active, abandoned, out-of-service, and proposed facilities. The design plans include a summary drawing showing the proposed facility route or excavation including streets and a locally accepted coordinate system. The plans are then distributed to the various facility owners/operators to provide the opportunity to furnish additional information, clarify information, or identify conflicts.
Examples of Practice: The City of San Antonio, Texas, Public Works Department requires three main phases of design in engineering contracts. The 30 percent design submittal includes existing utilities in plan and profile views, taken from existing records. During this phase, the designers have coordinated with the local facility owners/operators and coordinating council to learn what facilities are in the project area. The plans are obtained where available and shown and used in the design. Potential facility conflicts are noted in this phase. A summary drawing is included to orient the project and show the streets and major facilities.
The 60 percent design submittal updates the 30 percent submittal. This phase includes the balance of the field work, geotechnical information, and relative elevations on all facilities in potential conflict. It includes preliminary traffic control plans and Office of Safety and Health Administration (OSHA) requirement considerations. During this phase, the designers visit the site after the facilities have been located.
The 90 percent submittal includes final identification and resolution of conflicts with facilities, final facility designs, project schedule, and description of management of potential hazards.
Benefits: Providing complete underground facility information and including this information on design drawings reduces the hazards, simplifies coordination and minimizes the cost to produce the final project.
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