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Staff idea helps Manteca avoid $500K in water costs every 2 years
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Manteca is avoiding recurring costs of over $500,000 at least every two years by digging up city streets and laying new pipeline.

That new pipeline will deliver surface treated water to well heads at five different locations in Manteca. In doing so, it will dilute arsenic found naturally in ground water sufficiently to meet tough new Environmental Protection Act standards for arsenic established in 2005.

The blending solution that originated with the municipal public works staff avoids the cost of an expensive arsenic treatment plant at five municipal wells. The big saving is avoiding the need to replace extremely specialized media used to remove the arsenic that typically can last less than two years before having to be replaced. The filtering device cost replacement is $100,000 per well.

Manteca will still have to do that with seven of its 17 wells. It won’t with five that have - or will have - surface water blending. There are five other wells that do not need to reduce arsenic levels.

“Manteca had no problems meeting previous requirements before the (threshold) was increased,” noted Manteca Public Works Director Mark Houghton.

At the same time there has never been a health issue documented involving Manteca and water and arsenic-related sickness.

The previous standard was 50 parts per billion in terms of volume. It has now been reduced to 10 parts per billion. The 12 Manteca wells that are impacted are barely over the new standards that call an acceptable level of essentially one fifth the amount of arsenic.

Even so, Houghton noted it would take arsenic levels “about 100 times” higher than what they are now to cause sickness.

He termed the increased EPA standard as “extreme” caution.

Arsenic is a semi-metal element that is odorless and tasteless. It enters drinking water supplies from natural deposits in the earth or from agricultural and industrial practices based on a 2009 federal Environmental Protection Act report.

Arsenic ingested at sufficient concentrations can result in a variety of non-cancer effects including thickening and discoloration of the skin, stomach pain, vomiting, diarrhea, numbness in the hands and feet, paralysis and blindness. Carcinogenic effects of ingestion or exposure to arsenic at sufficient concentration have been documented to include cancer of the balder, lungs, skin, kidney, nasal passages, liver, and prostrate.

It cost the city $1.9 million and $3.1 million respectively to install arsenic treatment systems on Wells 24 and 25.

Manteca - due to its decision to secure treated surface water through the South San Joaquin Irrigation District and to use it primarily for peak demand times in the spring, summer and early fall - is in a better position than many valley cities such as Lodi and Stockton that rely primarily on well water.

Experts noted that arsenic occurs naturally in all water but at much higher concentrations in underground sources.

The wells that are being addressed with arsenic treatment plants are in the central part of the city and too far away from the main line to be cost effective for blending. As the wells age and possibly drop in productivity, the city will reassess the situation.