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National Primary Drinking Water Regulations: Long Term 1 Enhanced Surface Water Treatment and Filter Backwash Rule

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In proposed rule document 00-8155 beginning on page 19046 in the issue of Monday, April 10, 2000, make the following correction:

On pages 19057 and 19058, Table II.7 is corrected to read as follows:

Table II.7.—Cryptosporidium Occurrence in Filter Backwash and Other Recycle Streams

Name/location of studyNumber of samples (n)Type of sampleCyst/oocyst concentrationNumber of treatment plants sampledReference
Drinking water treatment facilities2backflush waters from rapid sand filterssample 1: 26,000 oocysts/gal (calc. as 686,900 oocysts/100L)2Rose et al. 1986.
sample 2: 92,000 oocysts/gal (calc as 2,430,600 oocysts/100L)
Thames, U.K.,not reportedbackwash water from rapid sand filterOver 1,000,000 oocysts/100L in backwash water on 2/19/891Colbourne 1989.
100,000 oocysts/100L in supernatant from settlement tanks during the next few days
Potable water supplies in 17 Statesnot reportedfilter backwash from rapid sand filters (10 to 40 L sample vol.)217 oocysts/ 100 L (geometric mean)not reportedRose et al. 1991.
Name/location not reportednot reportedraw water initial backwash water7 to 108 oocysts/100L detected at levels 57 to 61 times higher than in the raw waternot reported not reportedLeChevallier et al. 1991c.
Bangor Water Treatment Plant (PA)Round 1: 1 (8-hour composite)raw water filter backwash supernatant recycle6 oocysts/100L 902 oocysts/100L. 141 oocysts/100L.1Cornwell and Lee 1993.
Round 2: 1 (8-hour composite)raw water filter backwash supernatant recycle140 oocysts/100L 850 oocysts/100L. 750 oocysts/100L.1Cornwell and Lee 1993.
Moshannon Valley Water Treatment PlantRound 1: 1 (8-hour composite)raw water spent backwash supernatant recycle sludge13 oocysts/100L 16,613 oocysts/100L. 82 oocysts/100L. 2,642 oocysts/100L.1Cornwell and Lee 1993.
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Round 2: 1 (8-hour composite)raw water supernatant recycle20 oocysts/100L 420 oocysts/100L.1Cornwell and Lee 1993.
Plant “C”11 samples using continuous flow centrifugation; 39 samples using cartridge filtersbackwash water from rapid sand filters; samples collected from sedimentation basins during sedimentation phase of backwash water at depths of 1, 2, 3, and 3.3 mcontinuous flow: range 1 to 69 oocysts/100 L; 8 of 11 samples positive cartridge filters: ranges 0.8 to 252/100 L; 33 of 39 samples positive1Karanis et al. 1996.
Pittsburgh Drinking Water Treatment Plant24 (two years of monthly samples)filter backwash328 oocysts/ 100 L (geometric mean); (38 percent occurrence rate) non-detect-13,158 oocysts/100L.1States et al. 1997.
“Plant Number 3”not reportedraw water spent backwash140 oocysts/100L 850 oocysts/100L.not reportedCornwell 1997.
“Plant C” (see Karanis, et al., 1996)12 50raw water backwash water from rapid sand filtersavg. 23.2 oocysts/100L (max. 109 oocysts/100L) in 8 of 12 samples avg. 22.1 oocysts/100L (max. 257 oocysts/100L) in 41 of 50 samples1Karanis et al 1998 (Table 8, p. 14).
“Plant A”1rapid sand filter (sample taken 10 min. after start of backwashing)150 oocysts/100L
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[FR Doc. C0-8155 Filed 8-11-00; 8:45 am]