Plan calls for 1/4 of Highland’s water mains to be replaced

A study of Highland’s water distribution system, recommends about 25 percent of the city’s water mains be replaced over the next two decades. Estimated cost, about $14.5 million.

The city contracted Hurst-Rosche Inc. in June 2016 to preform a study on the water distribution system. The initial scope of the study was to evaluate the water system, provide a complete list of all city water mains, evaluate weak spots during a hydraulic analysis, and for the company to provide an opinion on the cost for the replacement of the water mains, based on priority.

Scott Hunt of Hurst-Rosche presented the findings of the water system study to the City Council on April 3. Hunt said the price tag may seem a bit daunting, but the city is really in a fairly good position.

“You guys are in a lot better shape than a lot of other communities,” Hunt said.

Hunt recommended that city officials utilize the compiled list and replace the mains based the highest scores.

“The No. 1 tool is that list of water-mains,” Hunt said.

At the top of the list is a 12-inch main near Trouw Nutrition. The line has been problematic and has had many breaks. A break there caused the entire city to be put under a boil order for two days last November.

More generally, the study found that the city should prioritize its cast iron for replacement first. This is because cast iron mains have the highest operating and maintenance cost and usually are the types of pipes with the most main breaks, Hunt said, adding that cast iron mains also create dirty water and are more likely to restrict flow because of buildup inside the pipe.

The second-highest priority found should be undersized mains. Hunt said the goal was to replace all lines less than six inches in diameter, especially if those mains were made of cast iron. The remaining mains that are less than six inches in diameter are PVC lines that do not, at the moment, have flow or pressure issues.

“I think it is a very fair evaluation of what mains are high on the replacement list,” said Director of Public Works Joe Gillespie.

The hydraulic analysis found that the city water distribution system is “fairly strong” hydraulically, and that only a few undersized lines and dead-ends need to be up-sized. According to the analysis, if the city were to replace the mains with the equivalent size, the system would still remain hydraulically strong.

The study was worked off of a 20-year time frame, which led Hurst-Rosche to recommend the city budget $727,500 per year for water main replacement.

This story was originally published April 14, 2017 at 8:00 AM with the headline "Plan calls for 1/4 of Highland’s water mains to be replaced."