Sligo City Watermains Rehabilitation Contract

The development of water supply into Sligo city dates back to the 1800’s with records of the construction of the impounding reservoir at Kilsellagh in 1884 and cast iron trunk mains feeding an open top reservoir at Farranacardy. Further improvements in treatment and extensions to the water distribution network were carried out throughout the 1900’s. Some of the watermains still in operation today, particularly in urban areas throughout Ireland date back to the early 1900’s and are generally of cast iron construction with no internal lining. Cement mortar lining was first introduced in the 1950’s, so mains installed prior to this date would be particularly susceptible to corrosion and encrustation of the wall of the pipe.

Improvements to the water network in Ireland gained momentum in the 1960’s, under of a number of different initiatives, both publicly and privately funded, and an array of different pipeline materials were introduced:

• Plastic pipe, typically of uPVC construction, was introduced in the 1960s. Yellow PVC pipes (with heated joints) were constructed in the period from 1958 to 1960. Green PVC pipes (with coupling joints) were constructed from 1960 onwards.
• Asbestos Cement mains were used primarily between the 1950s and 1980’s.
• The newer plastic mains, now being installed, have evolved over recent years with various types of PVC available, such as O-PVC and PVC-A, in addition to Polyethylene pipes.

In County Sligo and Sligo City, there are some Cast Iron Watermains dating back to the 1930’s, however, this is only a relatively small percentage. The majority of cast Irons mains were laid in 1950’s and 1960’s. Sligo could be classed as a predominately rural county; with Sligo County Council being responsible for over 1,470km of publicly owned and operated watermains. Over 3/4 of the pipeline stock is comprised of uPVC/HDPE, some of which has been inherited from privately operated Group Water Schemes down through the last 30 to 40 years.

There are 8 distribution systems in County Sligo that have been examined for rehabilitation prioritisation purposes, details of each can be seen in the Table no.1 below.

Table 1. Summary of DMA details