Riverdale Prepares to Start up New Water Treatment System

Appeared in The Minot Daily News
Thursday, October 26, 2006
By JILL SCHRAMM, Staff Writer

Jill Schramm/MDN Cory Chorne, with Advanced Engineering and Environmental Services, and Riverdale Mayor Tim Lingelbach stand in front of infrastructure in the water treatment plant that includes basins to house a new membrane filtration system.

RIVERDALE – After years of planning, research and design, the city of Riverdale is just a couple of weeks away from turning the tap on water coming from a new treatment system.

Membrane filters being installed in the Riverdale Water Treatment Plant are the first of their type to be used for treating surface water in North Dakota.

“It’s a fairly new technology for water treatment, and it seems to work very well,” said engineer Cory Chorne of Advanced Engineering and Environmental Services. The Bismarck firm has been working with Riverdale to develop the $2.8 million project, which will enable the city to continue meeting federal regulations for drinking water.

The sedimentation basin and sand and anthracite filter used in the old treatment system will become a pretreatment system. The building had enough space to accommodate the membrane filtration and a computerized operations system without the need for an addition.

Thousands of plastic membranes, which look similar to electrical wire sheathing, will be inside 2 1/2-foot by 2 1/2-foot cassettes. The Riverdale plant will have 88 of the cassettes immersed in two water basins. Pressure draws water into the membranes through pores so tiny that they are nearly invisible. The process removes particulates and micro-organisms that escape the pretreatment. This cleaner water than goes into the city’s reservoirs and distribution system.

Daily and quarterly cleaning of the membranes is a built-in function of the automated system. Cleaning consists of chlorine and acid baths. Repair or replacement of membranes also can be easily accomplished without shutting down the entire operation.

The existing plant is largely manually operated in terms of adding chemicals and controlling the operation and quality. The new system is computer-controlled with features that give the plant’s two operators a greater ability to monitor the plant’s activities.

Electronic monitoring of the entire treatment process will enable operators to adjust treatment to match any variance in the quality of the water coming in. It also will ensure better quality of water going out. If monitors show the treated water falls short of the quality standard, they will shut down the operation until operators can correct whatever is wrong.

The new treatment system will be able to produce up to 1.3 million gallons of water a day. It can produce water at the rate of 900 gallons a minute, compared to the current system that produces 600 gallons a minute.

Some of that additional water will be going to the city of Underwood and the surrounding rural area and lakeside developments through the North Central Regional Consortium.

Riverdale and Underwood, which faced losing its underground water supply because of coal-mining activity, had been discussing a joint water project since the mid-1990s. Increasing Environmental Protection Agency water standards put pressure on both cities to come up with a plan that was in compliance, yet affordable.

Riverdale considered various treatment options before settling on a membrane system provided by an Ontario company called Zenon.

“This seemed like the one that would produce the best quality of water and be the most reliable and most economical,” Chorne said.

“One of the things that really sold me,” Riverdale Mayor Tim Lingelbach said of the membrane technology, “was it was actually built to take care of wastewater, processing wastewater into drinking water. So it’s a pretty spectacular process.”

Lingelbach said the system has the added advantage of taking little space. The city saved thousands of dollars in avoiding a building expansion, he said.

The EPA paid about 55 percent of the project cost. A state loan also provided funding.

Riverdale’s water rates quadrupled in a series of increases over the past five years to bring rates up to where they need to be to pay for the project. The final rate adjustment goes into effect Nov. 1. However, Lingelbach noted Riverdale’s rates had been so low that they remain reasonable even with the increases.

Underwood’s water rates nearly tripled, but the city previously had been providing residents with untreated groundwater. About a week ago, Underwood began receiving water from the Riverdale plant through a newly constructed pipeline.

“It’s very cost effective to operate this plant. It’s been a good deal for everybody who has been involved with it,” Lingelbach said.

Having the quality water will improve Riverdale’s opportunity to grow, he said. Many of the lots in a new 45-unit campground have filled because people know they will be able to get good water, he said. The city now is looking at a 45-lot residential development.

The plant currently will serve about 1,500 homes, including about 350 summer residents of Riverdale.

“We are excited about it,” Lingelbach said. “It’s a huge thing for a rural area.”

“It’s a good thing for our community. We will be able to meet the drinking water standards,” Underwood Mayor Rick Olson said. “It’s so much more cost effective to do it as a big group than to do all that by yourselves.”

Lingelbach agreed. Without the participation of Underwood and the rural water system, the project that Riverdale would have been able to afford would have looked different, he said.

Bringing various entities together made for a more challenging project, though, Lingelbach said. They held many meetings and did a lot of research, including sending representatives to Colorado to look at a membrane system in operation there.

Riverdale now is a model that other cities in the state are looking at as they consider ways to stay in compliance with EPA regulations, Lingelbach said