Tap water experts give analysis of filter system

Published 12:00 am Friday, October 30, 2009



LAPLACE – St. John Parish Council members on Tuesday were told an excessive amount of “fouling” on filter membranes caused a shutdown of the water filtration system designed to remove contaminants from tap water in LaPlace.

Ray Rials, a principal engineer for MWH, the firm that installed the parish’s $3.3 million Nano Filtration system, told the council an examination of two membranes from the system showed heavy amounts of contaminants caused the system to malfunction and shut down back in August when, according to parish officials, tap water is at its peak demand. Rials said none of the membranes showed any structural damage in the shutdown.

The filter system, which services most of LaPlace, is designed to clear out contaminants from water pulled from wells near Ruddock. The system was installed in response to mandates from the Department of Health and Hospitals and the Environmental Protection Agency that the parish must eliminate high levels of trihalomethanes, a proven cancer-causing agent, from the region’s water supply.

Rials said the slimy residue found on the membranes was not a normal characteristic of the water from the well.

“The buildup is a characteristic of an unusual event that occurred when the tap water was at peak demand,” Rials said. “Were looking at a few different things that may have caused the shutdown.”

St. John Parish Acting Chief Administrative Officer Buddy Boe said the parish was not using the proper chemicals to treat the water before sending it to the filter system. Boe said following recommendations from General Electric Water, the designers of the system, the parish had been using small amounts of chlorine to remove bacteria from the water before it is filtered.

Rials said Tuesday chlorine treatment is not compatible with the system used in LaPlace. He said the parish should be using a chemical known as chloramine, which removes contaminants while not producing trihalomethanes. Boe said the parish has made the switch.

Rials said the membranes are being cleaned of the residue this week, and work should be completed by the end of next week. He said the system could be back on line about a week after that. Although he assured the council the system would run properly, many council members still were not satisfied.

“We just loved our beautiful clean water, and now it has been taken away from us,” said District 7 Councilwoman Cheryl Millet. “We have not gotten a straight answer from anyone as to when it will be back.”

District 4 Councilwoman Jaclyn Hotard questioned Rials and Parish Engineer C.J. Savoie about whether the system can adequately handle LaPlace’s water demands.

Savoie said the system was designed to process 4.5 million gallons per day, which is also the average amount of daily consumption in LaPlace. Savoie would not say the filter system was built too small but did acknowledge the parish has compensated by adding more storage tanks to handle peak time periods.

After the meeting council members said they were looking for some confidence that the system will work with no future malfunction.

“We paid for the system, and it worked, and we were all happy with it because we waited so long to get it up and running,” Hotard said. “I don’t think any of us will be satisfied until it is on and running properly. These guys are the experts. They should have definitive answers.”