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726 CHAPTER 11: Intermittent and Recirculating Packed-Bed Filters TABLE 11-99 Comparison of design flow based on a per capita allowance of 50 gaud times a peaking factor versus design flow based on a per bedroom allowance` Design flow Design flow based on based on per peak per bedroom Number of Number of Flowrate, Peaking capita flow, allowance, bedrooms persons gal/capita-d' factor gaud gal/d 1 2 50 2.5 250 150 2 3 50 2.5 375 300 3 4 50 2.5 500 450 4 5 50 2.5 625 600 'Adapted from Table 4-20. 'Flowrate per capita will vary with local conditions. The importance of the HAR can be appreciated by reviewing the information pre- sented in Table 11-10. At a Lw of 40 rnm/d (1 gal/ft�•d), if the filter were dosed once per day, the volume of the dose would represent 217 percent of the field ca- pacity of the medium. Clearly, most of the applied liquid will move down through and out of the filter. If, on the other hand, the filter were dosed 24 times/d the vol- ume of the dose would represent about 9 percent of field capacity. At 9 percent of TABLE 11-10 Analysis of volume per dose for various hydraulic loading rates and dosing frequencies for intermittent sand filters' Hydraulic Field Hydraulic Dosing application rate capacity loading rate, frequency, filled,' mm/d(gauft2-d) times/d mm/dose gal/W-dose % 40 (l) 1 40 1 217 2 20 0.5 107 4 10 0.25 53 8 5 0.12 26 12 . 3.3 0.083 18 24 1.67 0.042 9.0 81 (2) 1 81 2 427 2 40 1 217 4 20 0.5 107 8 10 0.25 53 12 6.75 0:12 26 24 3.38 0.083 . 16 163 (4) 1 163 4 855 2 82 2 427 4 41 1 217 A' 8 20 0.5 107 12 14 0.33 71 24 6.79 0.17 36 'For 1 ft2 of surface area and depth of 1.25 ft. t Five percent as volumetric water content(water volumettotal volume)from Bouwer(1978).