What is the bandwidth of your sewers?

Lorne Ross
Former Manager, Surface Projects Branch
Environment and Transportation Department
Regional Municipality of Ottawa-Carleton, Ontario
Member, UPROW Technical Committee

Deregulation of the telecommunications industry has spawned an onslaught of competitive service providers seeking to trench city streets to install fiber optic cable. Much of the trenching activity has occurred in an uncoordinated fashion producing chaos with communities enduring frequent interruptions to essential services, severe disruptions to traffic flow, and costly damage to pavements and existing underground infrastructure. The trenching works have further exposed workers and the public to work zone safety hazards, noise, vibrations and air pollution. A main downtown street in one major North American city was trenched 14 times in just a two-year period, resulting in public outcry. Study after study is showing that the reduced pavement life caused by trenching damage is costing major cities millions of dollars annually.

Yet the telecommunication providers must install their fiber. Until now, facilities-based competition, which involves each company owning its own fiber optic cables, has been a cornerstone model for achieving true competition in the telecommunications industry. Speed to market is essential for success. In response to these challenges public right-of-way managers and service providers are expending considerable effort working together pursuing workable solutions. To date these have included the concept of joint conduit builds, the installation of spare conduit, city-owned conduit, better trenching standards, improved coordination processes, better mapping and records systems, and improved quality control/quality assurance techniques. Emerging and competing "trenchless" technologies such as wireless and satellite transmission and the enhanced use of electric, cable TV and existing telecommunications copper wires may also help, especially for leaping across the so-called "last mile."

However, and notwithstanding all this, for the foreseeable future it appears that the enormous bandwidth capability of fiber optic cabling will be needed to carry the exponentially growing volume of electronic traffic. Despite the current telecommunications industry meltdown and the claim of a glut of fiber supply, some predictions are that much more fiber will need to be installed in cities' streets in coming years to meet the expected demand.

An innovative new technology that avoids most of the negative impacts of trenching by using robots to install fiber optic cables inside live storm and sanitary sewer pipes is emerging in North America. The robots can install fiber in sewer pipes as small as 8 inches at 30 to 60 percent less cost than trenching and two to six times faster. This technology would appear to be especially promising for streets that are so encumbered with underground infrastructure that there is little or no space remaining for more pipes, wires and cables (a common situation in many central business districts). The robot installation process requires the occupancy of relatively small street areas near sewer manholes and for only brief periods. Since there is no construction noise, work can often take place at night to further reduce disruption.

A number of North American cities, including Albuquerque, NM, Dublin, OH, Indianapolis, IN and Toronto, ON, have entered into sewer access agreements with companies and already have some fiber installed in their sewers. Many other cities are currently looking into the technology and some have recognized the use of their sewers for this purpose as a fundamental component of their telecommunications strategy. Sewer access agreements with cities can place the following obligations on proponent companies:

  • Submission of detailed technical information and fiber installation plans
  • Adherence to all City ordinances, state and federal laws, and industry standards
  • Cleaning and refurbishing the sewer
  • Provision of pre- and post-construction videotapes
  • Work to be carried out to City standards and requirements
  • Provision of "as-built" drawings
  • Relocation of equipment if required for City purposes
  • Maintenance of insurance and indemnifying the City against liability
  • Payment of compensation to cover all the City's costs and for the use of the sewer pipes
  • Use only of contractors approved by the City
Companies are using different variations of the robot technology. One company utilizes a 36-inch-long cylindrical robot which, after being lowered down a manhole into the sewer, installs steel rings and ducts on the inside of the sewer pipe every few feet to create space for the fiber, which is propelled through the pipes with air pressure. Another company uses a six-foot robot to affix armored and chemically resistant fiber cables to the roof of the sewer pipe using special fasteners. The position of the cables in the sewer can be adjusted by the robots to avoid conflicts with sewer laterals and other access points. For remote guidance and control purposes, the robots used for both methods are equipped with multiple onboard cameras. Less than three percent of the cross sectional area of a sewer is taken up by the fiber cables or ducts. Splices for service laterals leading to individual premises are made within the sewer manholes or in nearby handholes. Conventional installation methods (trenching, directional drilling or aerial) are employed to accommodate a lateral run between a manhole and a building being served.

Although new to North America, the robot technology has been used in Europe and Japan for a number of years. In view of the lack of familiarity on this continent, some cities have permitted their first installations only as pilot projects that are then subjected to a thorough testing, review, and analysis process. City officials invariably and understandably have many questions that must be addressed before reaching comfort with this technology. Cities may also need to adjust their normal maintenance, cleaning and inspection procedures to accommodate the fiber installations. The fiber-in-sewer technology has shown sufficient promise to prompt the American Society for Testing and Materials (ASTM) to initiate a project to develop standards for installing and operating fiber optic cables in existing sewer systems.

The placement of fiber optic cables in existing sewer infrastructure has the potential to be a "win-win" proposition. In addition to realizing a new source of revenue, a city could benefit from the more efficient and effective use of its scarce and valuable public rights-of-way. Telecommunications service providers could benefit from getting their products to market cheaper and faster. Businesses, residents and the community at large could benefit for all these reasons. Further information can be found on this subject by undertaking an Internet search using the key words "fiber" and "sewer."

Lorne Ross is a member of APWA's Utility and Public Right-of-Way Technical Committee and the former Manager, Surface Projects Branch, Environment and Transportation Department, Regional Municipality of Ottawa-Carleton, Ontario. He can be reached at (613) 738-3198 or at lorne.ross@rogers.com.