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Cottage Grove limits lawn watering as it struggles to filter out pollution

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As the lawns of Cottage Grove turn brown this summer, some homeowners will be able to point to an unlikely culprit: the pots and pans in their kitchens.

The city has declared an emergency ban on lawn watering because some of the city’s wells have been shut down. Water in those wells contains traces of chemicals used to manufacture Teflon and nonstick cookware, at levels that have been declared unsafe.

“Am I happy to have to deal with this? No,” said mayor Myron Bailey. “But I do not want to have someone turn on their faucet and have nothing come out.”

City officials are scrambling to respond to the announcement on May 22 that under new, stricter guidelines, eight of the city’s 11 wells had too much pollution. They have shut down the most polluted wells to make sure the water piped to households is safe.

Unfortunately, the shutdowns mean there is too little water for the usual summertime uses — irrigating lawns, watering gardens, filling pools and washing cars.

City engineer Jennifer Levitt said the water ban could last as long as six weeks, until the city can install temporary filters and reopen the wells.

In dealing with the pollution, Cottage Grove is learning from a city that has been through the same problem — Oakdale.

Oakdale's carbon filtration system at its water treatment plant utilizes ten 20-foot-tall filters, which are large tanks filled 3/4's full with carbon for filtering city water. These pipes carry water to and from the filters. The plant, paid for by the  3M corporation, is largely unmanned. The 10,000 pounds of carbon per filter is changed approximately once every two years.  (Scott Takushi / Pioneer Press)
Oakdale’s carbon filtration system at its water treatment plant utilizes ten 20-foot-tall filters, which are large tanks filled 3/4’s full with carbon for filtering city water. These pipes carry water to and from the filters. The plant, paid for by the 3M corporation, is largely unmanned. The 10,000 pounds of carbon per filter is changed approximately once every two years. (Scott Takushi / Pioneer Press)

In 2006, six of Oakdale’s nine wells were found to have water with high levels of PFCs, said Public Works Director Brian Bachmeier.

The city installed a filtration system, shut down one well and dug another. Bachmeier said the total cost of $4.7 million was paid by the 3M Co., which manufactured the chemicals.

Via email, 3M attorney William Brewer was asked if the company will reimburse Cottage Grove for the costs of dealing with PFC pollution.

His response: “3M will further assess the situation and, of course, act in accordance with its obligations and history of corporate stewardship.”

HOW IT STARTED

The chemicals — perfluorochemicals or PFCs — were made by 3M for use in Teflon, fire-extinguisher foam and stain repellent. The company put PFCs in dumpsites in Oakdale, Woodbury and Lake Elmo, ending in the 1970s. But in 2004, scientists found traces of the chemicals had leached into much of the groundwater of Washington County.

Until last week, the concentrations were considered low enough to be harmless.

Then came a surprise announcement — the acceptable level for the chemicals had been lowered.

The new guidelines for two types of PFCs are less than 35 parts per trillion — half the acceptable levels listed by the federal Environmental Protection Agency. Both federal and state officials say their limits will protect fetuses, babies and breast-feeding mothers.

Cottage Grove engineer Levitt said only one city well has levels of those two chemicals that are too high. But another seven wells have been declared unsafe not because of one pollutant, but because of the effect of many pollutants.

Water from the polluted wells, she said, contains a “family of chemicals” — slight variations of the perfluorochemicals that the state regulators mentioned.

Jim Kelly, program manager for the Minnesota Department of Health, explained that different pollutants can team up to magnify the danger of the water.

For example, if a water sample contains several pollutants that harm the liver, that sample might be declared hazardous — even if none of the individual pollutants exceeds allowable levels.

Kelly said the state has created a measurement system called Hazard Scores, to measure the overall impact of pollution. Usually, any water that has a higher score than 1 is considered polluted — and seven Cottage Grove wells have scores between 1.5 and 4, he said.

Levitt said a temporary filtration system should be installed in the next four to six weeks. After that, a permanent filtration system would be sought.

Meanwhile, the household water of Cottage Grove is coming from the remaining unpolluted wells, said Levitt. Does that mean it is safe to drink?

“Absolutely!” she told a reporter. “And I want you to print that word in big, bold letters.”

Mayor Bailey said the city is getting complaints — not about water safety, but about using the water outdoors.

“It’s things like ‘I want to fill my pool’ and ‘I just put in new sod,’ ” Bailey said.

Is he worried about his own lawn?

“I have a sprinkler system,” said Bailey, “but it will be turned off.”


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