rolled from each.

The dirty sand removed from the filters is carried by a portable
ejector through one or more lengths of 3-in. hose and a fixed line
of 4-in. pipe, to the sand washers. From the sand washers, the
washed sand is carried to the reinforced concrete storage bins, each
of which has a capacity of 250 cu. yd., and is at such an elevation
that carts may be driven under it and loaded through a gate.

Until April, 1909, the sand was replaced in the filters by carts
which were filled through the gates in the sand bins. It was then
hauled to the top of the filter beds and dumped through the manholes
on the chutes, which could be revolved in any direction. These
chutes were used to prevent the sand from being unduly compacted in
the vicinity of the manholes, and to facilitate spreading it in the
filters. Since April, 1909, all the sand has been replaced by the
hydraulic method. An ejector is placed under the gate in the sand
bin, and the sand is carried in a reverse direction from the bin
through the 4-in. piping and one or more lengths of hose to the
filter bed. This process has lowered the cost of re-sanding
considerably, and present indications are that it will prove
entirely satisfactory in every way.

The average effective size and uniformity coefficient of the filters
are shown in Table 1.

~Table 1--Filter Sand as Originally Placed.~
=======+===============+============+========+==========
Filter | Average | Average |Depth of| Average
No. |effective size,| uniformity |sand, in|turbidity.
|in millimeters.|coefficient.| inches.|
-------+---------------+------------+--------+----------
1 | 0.32 | 1.88 | 35.3 | 2,600
2 | 0.30 | 1.78 | 37.7 | 2,200
3 | 0.32 | 1.77 | 40.2 | 3,000
4 | 0.29 | 1.80 | 42.5 | 1,800
5 | 0.34 | 1.74 | 44.9 | 2,700
6 | 0.31 | 1.78 | 37.7 | 2,300
7 | 0.29 | 1.72 | 40.1 | 2,300
8 | 0.32 | 1.75 | 40.2 | 2,800
9 | 0.32 | 1.78 | 42.5 | 2,900
10 | 0.30 | 1.69 | 39.5 | 2,500
11 | 0.34 | 1.93 | 37.1 | 2,600
12 | 0.29 | 1.66 | 34.7 | 2,100
13 | 0.32 | 1.83 | 33.6 | 3,500
14 | 0.29 | 1.66 | 33.6 | 2,600
15 |