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<br />PHG. Achieving the water quality goal for arsenic could be approximately $2,610,000 per year,
<br />or $57 per service connection per year.
<br />Bromate – The BATs for removal of bromate in water for large water systems are:
<br />coagulation/filtration optimization, granular activated carbon, and reverse osmosis. Bromate
<br />was detected above the PHG in the treated surface water purchased from MWDSC. The City is
<br />in compliance with the MCL for bromate. The estimated cost to reduce bromate levels in
<br />MWDSC water to below the PHG of 0.1 µg/l using reverse osmosis was calculated. Because
<br />the DLR for bromate is 1 µg/l, treating bromate to below the PHG level means treating bromate
<br />to below the DLR of 1 µg/l. There are numerous factors that may influence the actual cost of
<br />reducing bromate levels to the PHG. Achieving the water quality goal for bromate could range
<br />from approximately $2,020,000 to $17,300,000 per year, or between $44 and $379 per service
<br />connection per year.
<br />Gross Alpha, Gross Beta, Combined Radium, and Uranium – The only BAT for the removal
<br />of gross alpha in water for large water systems is reverse osmosis, which can also remove
<br />gross beta, combined radium, and uranium, if detected. Gross alpha was detected above the
<br />MCLG in the local groundwater (Wells 18, 20, 21, 24, 26, 29, 30, 35, 36, 37, 39, 40, and 41) and
<br />treated surface water purchased from MWDSC. Gross beta was detected above the MCLG in
<br />the treated surface water purchased from MWDSC. Combined radium was detected above the
<br />MCLG in the treated surface water purchased from MWDSC. Uranium was detected above the
<br />PHG in the local groundwater (Wells 18, 20, 21, 24, 30, 33, 35, 36, 37, 39, 40, and 41) and
<br />treated surface water purchased from MWDSC. The cost of providing treatment using reverse
<br />osmosis to reduce gross alpha levels to the MCLG of 0 picoCurie per liter (pCi/l) (and
<br />consequently gross beta to below the MCLG of 0 pCi/l, combined radium to below the MCLG of
<br />0 pCi/l, and uranium in to below the PHG of 0.43 pCi/l) was calculated. Because the DLR for
<br />gross alpha is 3 pCi/l, treating gross alpha to 0 pCi/l means treating it to below the DLR of 3
<br />pCi/l (and treating gross beta, radium-226, radium-228, and uranium to below their respective
<br />DLRs of 4 pCi/l, 1 pCi/l, 1 pCi/l, and 1 pCi/l). Achieving the water quality goal for gross alpha
<br />could range from $10,500,000 to $89,800,000 per year, or between $230 and $1,970 per
<br />service connection per year.
<br />Hexavalent Chromium – The BATs for removal of hexavalent chromium in water for large
<br />water systems are: ion exchange, reduction/coagulation/filtration, and reverse osmosis.
<br />City of Santa Ana 6 2025 PHGs Report
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