A worker accidentally backwashing a filter at the East Lansing-Meridian Water and Sewer Authority (ELMWSA) treatment plant caused the problem that led to the August 5 Boil Water Advisory. Water plant superintendent Clyde Dugan has officially determined this as the root cause of the problem in his report to the Michigan Department of Environmental Quality (MDEQ).
According to the report, which was sent on August 12 to MDEQ as required by Michigan Safe Drinking Water Act rules, the water plant will update their filter controls to protect against an active filter being backwashed in the future. In addition, other technological updates have been proposed to the ELMWSA board for the water treatment plant.
ELMSWA provides drinking water to East Lansing and Meridian Township and is independent of those municipalities, although both make appointments to its board. The water plant is located on Burcham Road just east of Park Lake Road, near the start of the Interurban Trail.
According to Dugan, in the early hours of the morning on August 5th, an operator tasked with flushing Filter #2 at the water plant mistakenly flushed Filter #3 instead.
The accidental backwash of Filter #3, which was still connected to the water system, caused a release of tiny particles from the filter into the pool of finished water. This in turn caused “turbidity,” a clouding of the water with fine particulate matter. Turbidity itself isn’t dangerous, but it can indicate that the water has been improperly treated for drinking.
At 3:13 a.m,, the plant operator noticed that the backwash was not proceeding normally, and immediately interrupted the accidental backwash of the filter that was still connected to the water supply. The correct filter, Filter #2, was then backwashed and returned to service.
Filter #3 was taken out of service after the error was discovered, backwashed twice, and the sample lines were flushed. At that point, high turbidity was detected. As a result, the amount of chlorine disinfectant added to the finished water was immediately increased. The quantity of chlorine residuals was “maintained above MDEQ minimums,” according to the report.
MDEQ was notified of the incident at 8:35 a.m. that morning, and the Boil Water Advisory was issued shortly after that consultation. The advisory applied to all of East Lansing, as well as areas of Meridian Township located to the north of Kinawa Drive and Bennett Road. (See map.)
At 9:00 a.m., samples taken at the plant were showing turbidity levels below the action level of specified by MDEQ regulations. However, the plant’s continuous on-line monitoring was still showing turbidity levels in excess of action levels.
At 10:09 a.m., the on-line monitor was cleaned, flushed and recalibrated, at which point it showed turbidity levels below the action level. Dugan’s report to MDEQ therefore concludes that the emergency lasted less than 6 hours, but the Boil Water Advisory remained in place from Friday through Sunday while officials tested the water for bacterial problems to ensure there was no health risk to residents. At 1:05 p.m. on Sunday, August 7, and the boil advisory lifted.
To prevent similar emergencies in the future, two operators will need to be present at the plant when a backwash must be done on a filter. According to Dugan, this new approach at the plant will be enforced until additional procedural and technological changes are implemented at the plant. These include updated procedures and operator training, as well as the modifications to the control panel which will prevent filters from being backwashed while in service.
In addition to updates to procedures and technical training, Dugan’s report also reviews presentations he made to the ELMWSA Board of Trustees, proposing upgrades to the plant’s water treatment technology.