I am writing today to announce the closure of the New Mexico Independent. After three and a half years of operation in New Mexico, the board of the American Independent News Network, has decided to shift publication of its news…
While environmental activists played their part yesterday during demonstrations at the capitol building, going so far as to dress up as solar panels and to sing the tune of “You Are My Sunshine,” their counterparts, the anti-cap-and-trade contingency who has…
Roughly one quarter of University of New Mexico students are unimpressed with the state’s flagship public school, according to a survey that questioned college students about their higher education experiences.
Photo by Esther Gibbons.
Iron treatments are showing promise in reducing arsenic levels in Bernalillo‘s drinking water, according to lab data provided to The Independent by Town engineering firm Wilson & Company.
But it is too early to declare success, Project Manager Robert Paulette and Town Planning Director Maria Rinaldi agreed.
“Testing shows improvement in the quality of water,” Rinaldi said by email this week. “The Town is still implementing the Corrective Action Plan and until we have definitive data (through continued testing) and we can produce consistent, repeatable results on a longer term, it is premature to declare that the arsenic issue is fully resolved.”
Sludge remains a challenge
The Town has repeatedly opened up fire hydrants in an attempt to flush accumulated grayish-white aluminum sludge from the water distribution system, Rinaldi confirmed.
But now iron sludge is making its way into the Town’s treated water supply, much as aluminum sludge did when aluminum was used to remove arsenic from the water, Paulette acknowledged.
Asked whether the Town has simply traded white (aluminum) sludge in its tap water for red (iron) sludge, Paulette said that was a “possibility.”
Fired engineer’s design may be a factor
Levels of both iron sludge and arsenic repeatedly jumped after approximately 450,000 gallons or so had been treated, lab data show. That suggests a problem related to how the filters are cleared of sludge, Paulette said.
Arsenic levels in the treated water varied from 1.2 parts per billion to 68.4 parts per billion, the lab data show. The higher levels exceed the arsenic levels of raw well water and represent filtration problems that emerge after 450,000 gallons of well water have been treated, Paulette told The Independent.
The problem appears to be related to the way the system clears accumulating sludge from filters. After filters begin to become clogged, the system is “back-washed,” pushing water back through the filters to dislodge sludge, Town records show.
The sludge water is then stored for several hours in a “decanting” container, allowing sludge to settle our of the water. The decant water is then reintroduced to the treatment system.
Reintroducing decant water to the treatment system was intended to minimize the amount of waste water produced by the system. But the timing of the reintroduction of decant water coincides tightly with the sudden spike in arsenic and iron levels in the treated water, Paulette acknowledged, suggesting that sludge as well as the water from which it has settled, is being dumped back into the system.
“That could be due to operational actions that have allowed some amounts of settled sludge to be reintroduced as well,” Paulette acknowledged.
But ARS-USA engineer Eric Vogler suspects it is caused by a problem with the decant system’s design.
“(W)henever the backwash tank decants or empties back into the treatment system, the treatment is compromised in such a way as to lead to the breakthrough of both arsenic and iron through the filter system,” Vogler commented.
Vogler contends the treatment system’s failure to reduce arsenic levels and the repeated dumping of aluminum sludge into residents’ tap water, was not due to his firm’s aluminum treatment system, but to parts of the system designed by fired Town engineer Ramesh Narasimhan.
“This process of residual management where the sludge is physically removed from the facility and treatment process, is in dire need of modification,” Vogler said.
Paulette plans to temporarily truck decant water to the Town’s sewer plant using septic tank trucks, to see if removing it from the water treatment stream alleviates the sludge problem and periodic spikes in arsenic levels, he said.
Trucking away decant water is not a long-term solution, partly because it will cost $900 a day, Paulette estimated.
Treatment system may be rebuilt
But if it works, the Town could pay to redesign the backwash system and to add a pipeline and pump that would dump decant water directly into the sewer system, Paulette said. The sewer system is more than a mile from the drinking water treatment system.
The Town has set aside $1.2 million from an abandoned $9 million plan to build arsenic treatment systems at two old and currently unused wells, to cover the costs of re-engineering the active wells, Rinaldi said.
