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34, 35, 36, 37, 38, 39, and 41) and in the surface water supplied by MWDSC. The cost of providing treatment using reverse osmosis to reduce gross alpha levels in local groundwater and in MWDSC surface water to the MCLG of 0 picoCurie per liter (pCi/1) (and consequently gross beta in MWDSC surface water below the MCLG; and uranium in local groundwater and in MWDSC surface water below the PHG) was calculated. Because the DLR for gross alpha is 3 pCi/l, treating gross alpha to 0 pCi/I means treating it to below the DLR of 3 pCi/I. Achieving the water quality goal for gross alpha could range from $8,690,000 to $74,100,000 per year, or between $194 and $1,651 per household per year. Perchlorate — The BATS for removal of perchlorate in water are: ion exchange and biological fluidized bed reactor. Perchlorate was detected above the PHG in the local groundwater (Well 24). The City is in compliance with the MCL for perchlorate. The estimated cost to reduce perchlorate levels in local groundwater to below the PHG of 1 pg/I using ion exchange was calculated. Because the DLR for perchlorate is 4 pg/I, treating perchlorate to below the PHG level means treating perchlorate to below the DLR of 4 lag/l. There are numerous factors that may influence the actual cost of reducing perchlorate levels to the PHG. Achieving the water quality goal for perchlorate could range from $105,000 to $226,000 per year, or between $2.33 and $5.04 per household per year. All Contaminants — In addition, a cost estimate to treat all water produced or purchased by the City using ion exchange and reverse osmosis to remove all the contaminants detected above the PHGs or MCLGs was calculated. All the contaminants listed in the accompanying chart may be removed to non -detectable levels by ion exchange and reverse osmosis, except total coliform bacteria. As shown on the accompanying chart, achieving the water quality goals for all contaminants, except total coliform bacteria, using ion exchange and reverse osmosis could range from $8,800,000 to $74,300,000 per year, or between $196 and $1,657 per household per year. City of Santa Ana 8 2019 PHGs Report 75C-11