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<br />Hexavalent chromium was detected above the PHG in the local groundwater (Wells 18, 20, 21,
<br />24, 26, 29, 30, 33, 34, 35, 36, 37, 39, 40, and 41). The City is in compliance with the MCL for
<br />hexavalent chromium. The estimated cost to reduce hexavalent chromium levels in the
<br />groundwater to below the PHG of 0.02 µg/l using reduction/coagulation/filtration was calculated.
<br />Because the DLR for hexavalent chromium is 0.1 µg/l, treating hexavalent chromium to below
<br />the PHG level means treating hexavalent chromium to below the DLR of 0.1 µg/l. There are
<br />numerous factors that may influence the actual cost of reducing hexavalent chromium levels to
<br />the PHG. Achieving the water quality goal for hexavalent chromium could be approximately
<br />$17,800,000 to $111,000,000 per year, or between $390 and $2,440 per service connection per
<br />year.
<br />Perchlorate – The BATs for removal of perchlorate in water for large water systems are ion
<br />exchange and biological fluidized bed reactor. Perchlorate was detected above the PHG in the
<br />local groundwater (Wells 18, 20, 21, 24, 26, 30, 35, 36, and 39). The City is in compliance with
<br />the MCL for perchlorate. The estimated cost to reduce perchlorate levels in the groundwater to
<br />below the PHG of 1 µg/l using ion exchange was calculated. Because the DLR for perchlorate
<br />is 1 µg/l, treating perchlorate to below the PHG level means treating perchlorate to below the
<br />DLR of 1 µg/l. There are numerous factors that may influence the actual cost of reducing
<br />perchlorate levels to the PHG. Achieving the water quality goal for perchlorate could be
<br />approximately $3,370,000 to $7,400,000 per year, or between $74 and $162 per service
<br />connection per year.
<br />PFOS and PFOA – The BATs for removal of PFOS and PFOA in water for large water systems
<br />are: granular activated carbon, ion exchange, and reverse osmosis. PFOS and PFOA were
<br />detected above their respective PHGs in the local groundwater (Wells 18, 24, 26, 29, 33, 36, 39,
<br />40, and 41). The City is in compliance with the State requirements for PFOS and PFOA. The
<br />estimated cost to reduce PFOS and PFOA levels in the groundwater to below their respective
<br />PHGs of 1 nanogram per liter (ng/l) and 0.007 ng/l using ion exchange was calculated.
<br />Because the DDW Consumer Confidence Report Detection Level (CCRDL) for PFOS and
<br />PFOA is 4 ng/l, treating PFOS and PFOA to below their respective PHG levels means treating
<br />PFOS and PFOA to below the CCRDL of 4 ng/l. There are numerous factors that may influence
<br />the actual cost of reducing PFOS and PFOA levels to their respective PHGs. Achieving the
<br />water quality goal for PFOS and PFOA could be approximately $4,450,000 to $60,800,000 per
<br />year, or between $97 and $1,330 per service connection per year.
<br />City of Santa Ana 7 2025 PHGs Report
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