Manteca is preparing to spend $350,000 as part of an ongoing effort to avoid spending more than $1 million annually to meet tighter federal arsenic levels in drinking water.
The City Council last week put a call out for bids for the London Avenue and Austin Road metering facilities on the South County Water Project water transmission line that runs along Lathrop Road.
The project involves installing valves, utility vaults, flow meters, programmable logic controllers, radio communications and appurtenances at the two locations.
Lines have already been installed that will essentially mix surface water - that is essentially arsenic free -with water from five municipal wells to reduce the arsenic content. Seven other wells are having freestanding arsenic treatment plants built to meet federal standards at an average cost approaching $2 million apiece
Manteca ultimately will spend about $6 million upfront for arsenic treatment plants at the five wells where the water will be mixed with surface water. The city will end up spending over $4 million on pipelines and other improvements necessary to make the interconnect work and so it can be properly monitored and controlled.
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 media cost replacement is $100,000 per well.
The 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.
Manteca had no problem meeting the previous arsenic standards. 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, city officials have said it would take arsenic levels “about 100 times” higher than what they are now to cause sickness. They also have described the EPA edict 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.
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 to reduce arsenic treatment costs 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 arsenic treatment strategy is one reason why Manteca’s water rates have been unchanged for three consecutive years.