Human Error Caused OWASA Fluoride Overdose, OWASA Very Sorry About That | News
News
INDY Week's news blog

Archives | RSS

Friday, February 10, 2017

Human Error Caused OWASA Fluoride Overdose, OWASA Very Sorry About That

Posted by on Fri, Feb 10, 2017 at 2:37 PM

click to enlarge unknown.jpeg
An "unintentional [water treatment plant] operator key stroke"—literally, someone hit the wrong button—caused the overfeed of fluoride that forced OWASA to shut down its water plant last week, according to independent reports released Friday.

The extra fluoride dosage, plus a major water main break the next day, prompted a water shortage in Orange County that closed businesses, placed Chapel Hill and Carrboro under states of emergency, and sent residents scrambling to buy bottled water. Customers were unable to use or drink their water for more than twenty-four hours.

This afternoon, OWASA released reports on both the February 2 fluoride overfeed and the February 3 water main break.

According to the fluoride report, by CH2M HILL North Carolina, at 11:43 a.m. on February 2, a plant operator accidentally instructed the plant's fluoride feed pump to increase its feed rate to 80 percent, compared with its normal operating range of about 8–12 percent. The operator tried to change the command about twelve seconds later, but according to the report, the change didn't register.

"The pump appears to have operated at a rate significantly greater than the subsequent commanded speed for approximately 3.25 hours, resulting in a fluoride overfeed condition," the report says.

A lead operator at the plant noticed the extra high levels "but did not take corrective action, leading to the issue not being resolved until after 2:40 p.m."

A fluoride level of 5.90 mg/L was recorded at the plant that day, exceeding state and federal primary drinking water standards by 1.9 mg/L, the report says. (Fluoride is added to water to prevent tooth decay.)
click to enlarge CH2M HILL NORTH CAROLINA, INC.
  • CH2M HILL North Carolina, Inc.

The water main break, according to a report by AECOM Technical Services, may have been the result of the pipe bending because of pressure and settling. The pipe that broke, near the intersection of Summerfield Crossing Road and Foxcroft Drive, was buried three feet below the street.

"An increase in water pressure or an increase in external forces may have been responsible for the failure event. As the pipe is shallow, it would have been very sensitive to live loads—more so with an increased point load effect over the storm sewer below; so any combination of increased pressure, differential settling, or increased external loading (or increase in bending moment in this case) may
have initiated the failure," the report says.

The break leaked about 1.2 million gallons of water, causing pressure in the system to plummet. As a result, customers were ordered not to use or drink their water because low flow can allow bacteria to grow in pipes. Tests show the water was not contaminated.

The OWASA board of directors met Thursday night to discuss the water shortage and hear comments from the public and staff. Another meeting will be held February 23 at 7 p.m. in the Chapel Hill Town Hall.

“Last night, the Board agreed that OWASA would develop solutions to prevent the particular failures of last week, assess outage risks more broadly and take action to improve the water system resiliency, and review communication practices of OWASA and its partners during critical events. We may turn again to outside parties for both expertise and objectivity,"  John Young, chair of the OWASA Board of Directors, said in a statement. "OWASA apologizes for the significant disruptions and impact experienced by the community and thanks its many partners for their support.”

OWASA says it has stopped adding fluoride to the water, and The News & Observer reports that the agency is reviewing its policies and seeking public input before reintroducing it to the water supply.







Tags: , , , , ,

Pin It

Comments

Subscribe to this thread:

Add a comment

INDY Week publishes all kinds of comments, but we don't publish everything.

  • Comments that are not contributing to the conversation will be removed.
  • Comments that include ad hominem attacks will also be removed.
  • Please do not copy and paste the full text of a press release.

Permitted HTML:
  • To create paragraphs in your comment, type <p> at the start of a paragraph and </p> at the end of each paragraph.
  • To create bold text, type <b>bolded text</b> (please note the closing tag, </b>).
  • To create italicized text, type <i>italicized text</i> (please note the closing tag, </i>).
  • Proper web addresses will automatically become links.

Latest in News



Twitter Activity

Comments

I was diagnosed of hepatitis B in 2012,I have tried all possible means to get cure but all my effort …

by Austin calnor on The Problem with N.C.’s Religious Exemption Law (News)

"Since late November, Henderson County in Western North Carolina has seen 20 cases of pertussis, or whooping cough, and has …

by Liza Coutu on The Problem with N.C.’s Religious Exemption Law (News)

Most Read

Most Recent Comments

I was diagnosed of hepatitis B in 2012,I have tried all possible means to get cure but all my effort …

by Austin calnor on The Problem with N.C.’s Religious Exemption Law (News)

"Since late November, Henderson County in Western North Carolina has seen 20 cases of pertussis, or whooping cough, and has …

by Liza Coutu on The Problem with N.C.’s Religious Exemption Law (News)

What part of illegal don't they understand. Congress is considering the DACAs plus all other illegal aliens in a bill …

by john1050 on Durham Church Offers Immigrant Sanctuary from Deportation (News)

From the WRAL story:
http://www.wral.com/former-wake-register-o…
"John Stephenson, the county's internal auditor, said an average of $1,100 to …

by Mojo on Indictments in Wake Register of Deeds Scandal Charge Laura Riddick with Embezzling $926,615 (News)

Hopefully Indyweek will remember all this the next time they endorse a Republican (over and over again).

by Robert Larson on Indictments in Wake Register of Deeds Scandal Charge Laura Riddick with Embezzling $926,615 (News)

© 2017 Indy Week • 320 E. Chapel Hill St., Suite 200, Durham, NC 27701 • phone 919-286-1972 • fax 919-286-4274
RSS Feeds | Powered by Foundation