Stewart Fleming wrote:

"Four options were proposed to develop the network in three phases. The capital cost of the options ranged between approximately $700,000 and $7.6 million. The annual operating cost of the network is approximately $150,000. These different options and costs arise from the different methods costed out for laying the fibre network, *including the use of the DCC’s own wastewater ducting*. The study concludes that a combination of these methods may be the most cost-effective and efficient for different portions of each route." URBAN FIBRE NETWORK FEASIBILITY STUDY AND BROADBAND RECOMMENDATIONS Dunedin City Council, 24th January 2007 (emphasis added)

They're not the only ones - I knew I had read about it before: http://dc.internet.com/news/article.php/739281 "By routing fiber optic systems through sewers, CityNet avoids many of the problems associated with traditional trenching construction. The company installs the fiber networks and then leases them to telecommunications companies, Internet and network service providers and others that offer high-speed services." I believe I read a while ago about some other company which had developed a fiber laying robot for sewer systems right down to the standard dimension pipe into a residential household (100mm?)... quite a neat little thing. aj.