75D - PH WATER QUALITY - Laserfiche WebLink

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Copper The PHG for copper is 170 ug/L. There is no MCL for Copper. Instead the 90s' percentile value of all samples from household taps in the distribution system cannot exceed an Action Level of 1300 ug/L for copper. The category of health risk for copper is gastrointestinal imtation. Numerical health risk data on copper have not yet been provided by OEHHA, the State agency responsible for providing that information. All of our source water samples for copper in 2006 were less than the PHG. Based on extensive sampling of our distribution system in 2006, our 90`h percentile value for copper was 200 ug/L. Our water system is in full compliance with the Federal and State Lead and Copper Rule. Based on our extensive sampling, it was determined according to State Regulatory requirements that we meet the Action Levels for copper. Therefore, we aze deemed by CDHS to have "Optimized Corrosion Control" for our system. In general, optimizating corrosion control is considered to be the best available technology to deal with corrosion issues and with any lead or copper findings. We continue to monitor our water quality pazameters that relate to corrosively, such as pH, hazdness, alkalinity, and total dissolved solids. Action will be taken if necessary to maintain our system in an "Optimized Corrosion Control" condition. Since we aze meeting the "Optimized Corrosion Control" requirements, it is not prudent to initiate additional corrosion control treatment as it involves the addition of other chemicals, and there could be additional water quality issues raised. Therefore, no estimate of cost has been included. Arsenic The PHG for arsenic is 0.004 ug/L. The MCL for azsenic is 10 ug/L. We have detected Arsenic in 3 of our 20 wells at levels ND - 3.2 ug/L. The levels detected were below the MCL. The category of health risk associated with Arsenic, and the reason that a drinking water standazd was adopted for it, is that people who drink water containing Arsenic above the MCL throughout their lifetime could experience an increased risk of cancer. The 10 ug/L MCL established by the USEPA if complied with should have no health effect. The numerical risk for cancer for water containing Arsenic at the PHG level of 0.004 ug/L is one case in 1,000,000. The large system BAT for Arsenic to lower the levels below the PHG is Ion Exchange. Total water production for all affected wells is 7,260 gallons per minute. Based on the USEPA studies, the initial cost to treat one thousand gallons of water at 80 percent removal efficiency for lazge water systems ranges from $0.50 to $0.65. The on going cost for the treatment ranges from $0.50 to $0.65 per thousand gallons of water treated. For the City of Santa Ana, the estimated cost to install such treatment systems (Ion Exchange) ranges between $6.45 and $20.0 Million. The cost to operate the treatment facilities will range from $6.45 to $7.9 million per yeaz. The cost to build the treatment facilities would result in an assumed increased to each customer or $18.53 to $57.45 in the first yeaz and from $18.50 to $22.70 per customer annually. 3 75D-5