~Table 15~--(_Continued._) (_B_) ~Per Cubic Yard of Sand.~ =============+=======+=======+=======+=======+=======+=======+========= Month. | Scrap-| Eject-| Wash- |Smooth-|Raking.| Re- | Total. | ing. | ing. | ing. | ing. | |sanding.| -------------+-------+-------+-------+-------+-------+--------+-------- 1909. -------------+-------+-------+-------+-------+-------+--------+-------- July | $0.08 | $0.15 | $0.03 | $0.01 | ... | $0.10 | $0.37 August | 0.07 | 0.15 | 0.03 | 0.01 | ... | 0.11 | 0.37 September | 0.07 | 0.17 | 0.03 | 0.01 | ... | 0.17 | 0.45 October | 0.06 | 0.15 | 0.03 | 0.01 | ... | 0.09 | 0.34 November | 0.10 | 0.23 | 0.02 | 0.02 | ... | ... | 0.37 December | 0.12 | 0.25 | 0.04 | 0.02 | ... | 0.08 | 0.51 -------------+-------+-------+-------+-------+-------+--------+-------- 1910. -------------+-------+-------+-------+-------+-------+--------+-------- January | 0.10 | 0.19 | ... | 0.02 | ... | ... | 0.31 February | 0.07 | 0.15 | ... | 0.01 | ... | 0.09 | 0.32 March | 0.06 | 0.11 | ... | 0.02 | ... | 0.08 | 0.27 April | 0.07 | 0.09 | 0.03 | 0.01 | ... | 0.05 | 0.25 May | 0.06 | 0.09 | 0.03 | 0.01 | ... | 0.06 | 0.25 June | 0.06 | 0.12 | ... | 0.01 | ... | 0.10 | 0.29 -------------+-------+-------+-------+-------+-------+--------+-------- Average | 0.07 | 0.14 | 0.02 | 0.01 | ... | 0.10 | 0.34 -------------+-------+-------+-------+-------+-------+--------+-------- Fiscal years: -------------+-------+-------+-------+-------+-------+--------+-------- 1905-06 | 0.07 | 0.35 | 0.04 | 0.07 | ... | 0.14 | 0.67 1906-07 | 0.06 | 0.19 | 0.03 | 0.02 | ... | 0.17 | 0.47 1907-08 | 0.09 | 0.15 | 0.03 | 0.01 | ... | 0.14 | 0.42 1908-09 | 0.06 | 0.14 | 0.03 | 0.01 | ... | 0.13 | 0.37 =============+=======+=======+=======+=======+=======+=======+========= For convenience in referring to the different systems, the combined rapid and slow sand filter will be designated as Filter Plant No. 1, the combined Maignen scrubber and slow sand filter as Filter Plant No. 2, and the combined coagulating basin and slow sand basin as Filter Plant No. 3. The length of run of Filter Plant No. 1 was relatively long at first. The rapid rate of filtration, however, tended to carry the clay, which was suspended in the applied water, to a considerable depth in the filtering material, so that the runs gradually decreased in length until they were reduced to about three days. Unfortunately, it was necessary to use unfiltered water for washing, which, together with the great penetration from the applied water, finally made it necessary to remove all the filtering materials, and wash them.