With a maintenance agreement inked, new equipment is currently being installed on Chelsea’s water softening system, which means softer water will be delivered to water customers sometime next week.

Chelsea officials announced this week that a five-year maintenance agreement between the city and GE Water Technologies for its water treatment plant’s reverse osmosis water softening system has been finalized.

When the water softening system becomes fully operational, the city will pay GEWT $13,536 a month — or approximately $162,000 yearly — under the agreement.

Comprising two reverse-osmosis skids, the water softening system was taken off line April 19.

Since then, customers have received water with a mineral hardness content measured at approximately 400 parts per million.

Repairs are currently being made to RO Unit 2, one of the reverse osmosis skids.

With that unit functional, water customers will receive water with a target hardness of 200 parts per million. Achieving that target, however, will depend on water system demands, which in turn will be determined by how much water will be bypassed from that unit.

While new reverse osmosis membranes are installed on Unit 2, technicians will inspect the unit’s stainless steel housings for corrosion damage.

Corrosive pitting has been found on Unit 2’s housings. A determination will be made regarding whether the housings can be salvaged.

Stainless steel housings on Unit 1, which developed pinhole leaks, will be replaced.

If the housings on Unit 2 need replacement, those repairs will take place only after Unit 1 is brought on line.

GEWT representatives have reported that the leaks were most likely caused by a combination of corrosion and bacteria.

The bacteria were theorized to have fed on suspended materials brought into the softeners by a failure in the plant’s iron removal process.

Whether or not the iron removal process at the plant is malfunctioning, however, has not been definitively proven.

The GEWT agreement will entail system monitoring, membrane cleaning and replacements, and reverse osmosis system troubleshooting. The agreement also covers costs for replacement membranes, and new housings, filters and chemicals involved in the reverse osmosis process.

The reverse osmosis system will be monitored through water sampling, conductivity and pressure testing.

The city will review plant operations every six months. If the system performs better than expected, monthly costs to the city could be reduced if less replacement or maintenance materials are needed.

Chelsea City Manager Mike Steklac said Tuesday that the costs for the agreement would be paid though the city water department’s yearly budget.

"We don’t expect that the cost of the agreement will be too much more than what we are currently paying for chemicals and cartridge filters," Steklac said.

Capital costs related to water system problems encountered in the last few years will go into long-term bond, paid over a 15-year period.

Steklac said he doesn’t know yet if the water system problems will result in future water rate hikes.

City officials will work with the Michigan Rural Water Association to prepare a cost model, which will determine where the rates should be set to meet obligations to bondholders and to provide for operation of the water system.

Steklac said he hopes the GEWT agreement will identify problems in the reverse osmosis system.

In the past, the plant’s water softening membranes, which are designed to last for up to five years, have clogged with waste materials in less than one year.

Half of the plant’s 36 membrane filter tubes on the plant’s two skids were completely clogged before the softening system was taken off line in April.

The question now is whether the reverse osmosis problems are a result of the city’s operation of the system, a design problem, or a combination of both factors.

"If it’s determined that the membranes will need to be replaced every year and the cartridge filters every week no matter how the system is operated, then we will have to program those costs into the water department budget," Steklac said.

On the other hand, Steklac said the agreement would save customers money in the long term if plant problems are identified and the membranes last longer than one year.

A timetable for getting Unit 1 operational again has not yet been determined, but Steklac said he hopes the unit will be on line by September.

With both units working at full capacity, water will be delivered to customers with a mineral hardness level at about 100 parts per million.

If the diagnosis of Unit 2 yields answers for the past problems, Steklac said remedies for those problems would be applied before RO Unit 1 is put back into service.

For now, Steklac said he expects Unit 2 will run at full capacity. It will take a few days for the softer water to work its way through municipal pipelines before it reaches water customers, Steklac said.