ASCE Manual of Practice No. 118 For Belowground Pipeline Networks For Utility Cables

U-Tech: Underground Technology Cutting Edge Technical Information for Utility Construction and Rehabilitation
By Dr. Lawrence M. Slavin, Dr. Oleh Kinash, Dr. Mohammad Najafi | January 2010 Vol. 65 No. 1
Figure 2 Typical Underground Conduit Construction (Courtesy of Underground Devices, Inc.)

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Figure 7 High Air-Speed Blown-Cable Principle of Operation
(Courtesy of Outside Plant Consulting Services, Inc.)

Hybrid belowground cable networks
Section 5 of the manual provides specific design and implementation rules for a hybrid cost-effective, space efficient joint-trenching system for utility cables combining the advantages of direct-buried and underground conduit construction methods. Such Belowground Cable Network (BCN) systems are intended to represent cost-effective, space-efficient overall solutions for direct-buried utility (electric power, telephone, and CATV) or miscellaneous communication lines. These systems provide an opportunity for conveniently and safely accomplishing cable upgrades, at a relatively low initial incremental cost to the utilities and/or their customers, as well as resulting in long-term savings on a life cycle basis. Although Section 5 focuses on one type of such a network, as illustrated in Figure 8, other designs or architectures may possibly be developed to accomplish similar objectives.

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Figure 8 Example BCN Architecture
(Courtesy of Outside Plant Consulting Services, Inc.)

An important feature of the BCN is the use of cost-effective joint (shared) construction practices, consistent with optimized utility practices. Thus, a single main trench along the right-of-way would be used for several utilities or organizations, as well as a single service trench to each home (or small business) for residential type applications, as appropriate. The size and type of the indicated initially installed (direct-buried) distribution cables would be selected based upon the conventional engineering rules used by the utilities, in their initial attempt to meet present and future (ultimate) anticipated needs. The BCN upgrade capability would only be used to meet unanticipated needs that nonetheless often arise, due to the desire to introduce new technologies, increase capacities and/or replace degraded cables and wires.