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AMERICAN SOCIETY OF CIVIL ENGINEERS
INSTITUTED 1852
TRANSACTIONS
Paper No. 1191
WATER PURIFICATION PLANT, WASHINGTON, D. C.
RESULTS OF OPERATION.[1]
~By E. D. Hardy, M. Am. Soc. C. E.~
~With Discussion by Messrs. Allen Hazen, George A. Johnson,
Morris Knowles, George C. Whipple, F. F. Longley, and E. D. Hardy.~
The Washington filtration plant has already been fully described.[2]
At the time that paper was written (November, 1906), the filtration
plant had been in operation for only about 1 year. It has now been
in continuous operation for 5 years, and many data on the cost,
efficiency, and methods of operation, have accumulated in the
various records and books which have been kept. It is thought that a
brief review of the results, and a summary of the records in tabular
form, will be of interest to the members of the Society, and it is
also hoped that the discussion of this paper will bring out the
comparative results of operation of other filter plants. As a matter
of convenience, the following general description of the plant is
given.
_Description of the Filtration Plant._--The Washington filtration
plant was completed and put in operation in October, 1905. It
consists of a pumping station for raising the water from the
McMillan Park Reservoir to the filter beds; 29 filters of the slow
sand type, having an effective area of 1 acre each; the
filtered-water reservoir, having a capacity of about 15,000,000
gal.; and the necessary piping and valves for carrying water,
controlling rates of filtration, etc.
[Footnote 1: Presented at the meeting of February 15th, 1911.]
[Footnote 2: "Works for the Purification of the Water Supply of
Washington, D. C.," by Allen Hazen and E. D. Hardy, Members, Am.
Soc. C. E., _Transactions_, Am. Soc. C. E., Vol. LVII, p. 307.]
In the pumping station, there are three centrifugal pumps, which are
directly connected to tandem compound engines; two sand-washer
pumps; three small electric generating sets for furnishing electric
light; and four 200-h.p., water-tube boilers.
Each of the centrifugal pumps has a nominal capacity of 40,000,000
gal. per day when pumping against a head of 21 ft., and each
sand-washer pump has a capacity of 2,500,000 gal. when pumping
against a head of 250 ft. The electric light engines and generators
supply the current for lighting the pumping station, the office and
laboratory and other buildings, and also the courts and interior of
the filter beds, and for operating a machine-shop.
The filters and filtered-water reservoir are built entirely of
concrete masonry. The floors are of inverted groined arches on which
rest the piers for supporting the groined arch vaulting. All this
concrete work is similar to that in the Albany, Philadelphia, and
Pittsburg filters.
The filters contain, on an average, 40 in. of filter sand and 12 in.
of filter gravel. The gravel is graded from coarse to fine; the
lower and coarser part acts as part of the under-drain system, and
the upper and finest layer supports the filter sand. The raw water
from the pumps is carried to the filters through riveted steel
rising mains which have 20-in. cast-iron branches for supplying the
individual filters. The filtered water is collected in the
under-drainage system of the several filter beds, and is carried
through 20-in., cast-iron pipes to the regulator-houses. These
regulator-houses contain the necessary valves, registering
apparatus, etc., for regulating the rate of filtration, showing the
loss of head, shutting down a filter, filling a filter with filtered
water from the under-drains, and for turning the water back into the
raw-water reservoir, or wasting it into the sewer. From the
regulator-houses, the filtered water flows directly to the
filtered-water reservoir. Generally, five filters are controlled
from one house, but there are two cases where the regulator-houses
are smaller, and only two filters are controlled 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 | 0.33 | 1.75 | 39.0 | 2,400
16 | 0.33 | 1.78 | 42.3 | 3,000
17 | 0.33 | 1.86 | 45.5 | 3,300
18 | 0.34 | 1.80 | 48.7 | 3,100
19 | 0.34 | 1.80 | 52.0 | .....
20 | 0.34 | 1.87 | 39.0 | 2,700
21 | 0.32 | 1.82 | 42.3 | 2,400
22 | 0.33 | 1.74 | 45.5 | 2,200
23 | 0.33 | 1.81 | 48.7 | 2,300
24 | 0.35 | 1.80 | 52.0 | 2,600
25 | 0.29 | 1.64 | 39.5 | 2,400
26 | 0.31 | 1.71 | 37.1 | 2,100
27 | 0.31 | 1.71 | 34.7 | 1,900
28 | 0.33 | 1.93 | 33.6 | 2,300
29 | 0.34 | 1.93 | 33.6 | 3,000
-------+---------------+------------+--------+----------
Maximum| 0.36 | 1.93 | 52.0 | 3,300
Minimum| 0.29 | 1.64 | 33.6 | 1,800
Average| 0.32 | 1.77 | 40.4 | 2,600
=======+===============+============+========+==========
_Description of Washington Aqueduct._--The water supply of
Washington is taken from the Potomac River, at Great Falls, about 16
miles above the city. At that place, a dam has been built across the
river, which holds the water at an elevation of 150.5 ft. above mean
tide at Washington. From Great Falls the water flows by gravity for
a distance of 16 miles through a 9-ft. conduit, three reservoirs,
and a tunnel. From McMillan Park Reservoir, the last of the three,
the water is lifted by centrifugal pumps about 21 ft. to the
filters. After passing through the filters, it flows to the
filtered-water reservoir, and later to the city mains. In its
passage from Great Falls to the filters, the water flows through
three settling reservoirs, which have already been referred to.
These reservoirs are known as the Dalecarlia, the Georgetown, and
the McMillan Park Reservoirs, and have available capacities of
141,000,000, 140,000,000, and 180,000,000 gal., respectively.
_Turbidity._--The Potomac River water is rather turbid, the
turbidity being caused by very fine particles of clay. The river is
subject to sudden fluctuations, it being no uncommon thing to have a
turbidity of 100 one day, and 1,000 the next. The high turbidity
usually disappears about as rapidly as it comes, and is seldom
higher than 500 for more than 5 days at a time. It is frequently the
case, however, that a succession of waves of high turbidity will
appear so close together that the effect of one has not disappeared
before that of another is felt.
The clarification of the water supply begins at the dam at Great
Falls. Here it is a clarification by exclusion, for when an
excessive quantity of mud appears in the river water, the gates are
closed, and the muddy water is allowed to flow over the dam and form
mud-bars in the Lower Potomac, while the city is supplied from the
water stored in the three settling reservoirs. Until a comparatively
recent date, the excessively muddy water was never excluded, having
been taken, like other decrees of Providence, as it came.
During the summer of 1907, the practice of shutting out water with a
turbidity of 500 or more was established for the warm months. This
practice was discontinued during the cold months, as it was feared
that a very high consumption of water might occur at the time of low
water in the reservoirs, and so cause a partial famine. During the
winter of 1909-10, however, the gates were closed, as was the
practice throughout the summer months.
When the reservoirs are well filled, and the consumption of water
is less than 70,000,000 gal. per day, it is safe to close the gates
at Great Falls for a period of about 4 days.
[Illustration: ~Figure 1--Plan and Profile of Washington Aqueduct.~]
While a considerable reduction in turbidity is effected in each of
the reservoirs, the bulk of the mud is deposited at the upper end of
Dalecarlia Reservoir. This reservoir had become so completely
filled, that, in 1905, it was necessary to dredge a channel through
the deposit, in order to allow the water to pass it. During the
summers of 1907 and 1908, a 10-in. hydraulic dredge removed more
than 100,000 cu. yd. of mud which had been deposited in this
reservoir. The mud deposited in Georgetown and McMillan Park
Reservoirs is so fine that the accumulation of many years is not
very noticeable in its effect on the depth of water.
The particles of clay which remain in the water after its passage
through the three reservoirs, are so exceedingly small that they do
not settle out in any reasonable length of time. Even the filtration
of the water through one or more slow sand filters occasionally
fails to remove the last trace of turbidity. This is especially true
in the colder months, and not a winter has passed when the water
supply has not been noticeably turbid at some time.
A general idea of the quantity of mud contained in the river water,
the quantity excluded by closing the gates at Great Falls, and that
removed by sedimentation and filtration, may be gained from Table 2,
which is, of course, only a rough approximation.
Table 2 also shows that the gates were closed 10.50% of the time,
thereby excluding 40.06% of the total suspended matter which
otherwise would have entered the system.
The turbidities, bacterial counts, and chemical analyses of numerous
samples of water are shown in Tables 3, 4, 5, and 6. The amount of
work done in the pumping station, average consumption of water,
death rate from typhoid fever, and filter runs are shown in Tables
7, 8, 9, and 10.
_Raking._--At the time the filters were first put in service, the
sand bins had not been completed, and, consequently, the work of
cleaning the filters was carried on in the old-fashioned way of
scraping by hand and wheeling out the sand in barrows. This method
of cleaning was used from October, 1905, to April, 1906; then the
regular sand-handling system was commenced.
At times, during the first two summers the filters were in
operation, considerable difficulty was experienced in keeping them
cleaned as fast as was necessary to provide an ample supply of
filtered water. For a short period in each summer it was found
necessary to organize night shifts, and keep the work of cleaning
in progress for from 16 to 24 hours per day.
[Illustration: ~Figure 2--General Plan of Washington Filtration Plant
Showing Finished Surfaces.~]
~Table 2--Tons of Suspended Matter Entering System, Etc.~
Columns:
A - Amount that would have entered the system if the gates
had been left continuously open.
B - Number of hours gates were closed.
C - Amount shut out.
D - Amount deposited in Dalecarlia Reservoir.
E - Amount deposited in Georgetown Reservoir.
F - Amount deposited in McMillan Park Reservoir.
G - Amount entering filtration plant.
=========+=======+=======+=======+=======+=====+=====+=====+========
Month. | A | B | C | D | E | F | G | Total.
---------+-------+-------+-------+-------+-----+-----+-----+--------
1909.
---------+-------+-------+-------+-------+-----+-----+-----+--------
July | 318 | 32.0 | 3 | 0 | 125 | 74 | 116 | 318
August | 146 | 47.0 | 1 | 0 | 78 | 38 | 29 | 146
September| 97 | 57.0 | 7 | 21 | 13 | 38 | 18 | 97
October | 61 | 90.5 | 8 | 7 | 9 | 25 | 12 | 61
November | 50 | 60.0 | 4 | 13 | 5 | 17 | 11 | 50
December | 370 | 99.0 | 126 | 108 | 33 | 59 | 44 | 370
---------+-------+-------+-------+-------+-----+-----+-----+--------
1910.
---------+-------+-------+-------+-------+-----+-----+-----+--------
January | 2,410 | 136.0 | 1,109 | 1,020 | 67 | 117 | 97 | 2,410
February | 839 | 117.5 | 481 | 126 | 56 | 75 | 101 | 839
March | 208 | 7.5 | 13 | 43 | 15 | 13 | 124 | 208
April | 321 | 65.0 | 17 | 195 | 43 | 43 | 23 | 321
May | 197 | 84.5 | 58 | 54 | 22 | 24 | 39 | 197
June | 1,505 | 124.0 | 786 | 535 | 49 | 88 | 47 | 1,505
---------+-------+-------+-------+-------+-----+-----+-----+--------
Total | 6,522 | 920.0 | 2,613 | 2,122 | 515 | 611 | 661 | 6,522
=========+=======+=======+=======+=======+=====+=====+=====+========
In order to relieve the situation at such times, the expedient of
raking was tried. This was first attempted with the filters filled
with water; the effluent was first shut off in order to prevent a
downward flow of water, and the filter was then raked or harrowed
from boats. This method was not satisfactory, however, as the work
was neither as uniform nor as thorough as necessary. Later, the
filters were drained to the necessary depth, and the surface of the
sand was thoroughly stirred with iron garden rakes. The filters were
then filled with filtered water through the under-drains and put in
service.
This latter method proved so satisfactory that it has been resorted
to at all times when the work was at all pressing. When the runs
were of short duration, and the depth to which the mud had
penetrated the filter sand was slight, a raking seemed to be nearly
as effective in restoring the filter capacity as a scraping; it
could be done in 8 hours by 3 laborers, and there seemed to be no
ill effects from lowered efficiency.
~Table 3--Turbidities.~
Average by Months.
(United States Geological Survey Standard.)
==========+============+=============================================
| | ~Reservoirs:~
| +-----------+-----------+------------+--------
Month. |Great Falls.| Dalecarlia| Georgetown| McMillan |Filtered
| | Outlet. | Outlet. | Park. | water.
| | | | Outlet. |
+------+-----+-----+-----+-----+-----+------+-----+----+---
| Max. | Ave.| Max.| Ave.| Max.| Ave.| Max. |Ave. |Max.|Ave
----------+------+-----+-----+-----+-----+-----+------+-----+----+---
1905.
----------+------+-----+-----+-----+-----+-----+------+-----+----+---
October | 100 | 36 | 40 | 21 | 32 | 18 | 20 | 11 | 4 | 1
November | 35 | 19 | 34 | 19 | 22 | 14 | 14 | 11 | 3 | 1
December |1,500 | 199 | 250 | 84 | 150 | 74 | 95 | 39 | 14 | 6
----------+------+-----+-----+-----+-----+-----+------+-----+----+---
1906.
----------+------+-----+-----+-----+-----+-----+------+-----+----+---
January | 700 | 94 | 180 | 60 | 120 | 60 | 85 | 52 | 20 | 12
February | 120 | 45 | 85 | 41 | 55 | 29 | 35 | 22 | 5 | 3
March |1,750 | 272 | 350 | 181 | 120 | 56 | 90 | 46 | 8 | 6
April |1,270 | 167 | 180 | 72 | 95 | 58 | 75 | 46 | 12 | 7
May | 600 | 56 | 50 | 20 | 45 | 16 | 34 | 10 | 3 | 2
June |1,700 | 303 | 500 | 125 | 450 | 94 | 180 | 41 | 13 | 2
July |1,000 | 130 | 180 | 54 | 150 | 47 | 250 | 43 | 13 | 3
August |1,530 | 375 | 250 | 112 | 95 | 66 | 65 | 45 | 5 | 2
September | 120 | 33 | 180 | 34 | 95 | 28 | 75 | 25 | 7 | 2
October |1,025 | 127 | 110 | 37 | 60 | 24 | 55 | 21 | 1 | 1
November | 160 | 27 | 75 | 20 | 45 | 16 | 24 | 13 | 1 | 1
December | 600 | 69 | 110 | 31 | 80 | 28 | 80 | 26 | 8 | 2
----------+------+-----+-----+-----+-----+-----+------+-----+----+---
1907.
----------+------+-----+-----+-----+-----+-----+------+-----+----+---
January | 400 | 135 | 150 | 70 | 110 | 75 | 70 | 53 | 11 | 7
February | 55 | 26 | 26 | 15 | 36 | 16 | 40 | 17 | 5 | 2
March | 950 | 248 | 180 | 77 | 130 | 70 | 90 | 57 | 7 | 4
April | 200 | 47 | 80 | 33 | 60 | 30 | 45 | 24 | 4 | 2
May | 130 | 29 | 40 | 18 | 26 | 15 | 14 | 9 | 1 | 1
June | 400 | 104 | 160 | 48 | 75 | 32 | 40 | 18 | 1 | 1
July | 600 | 114 | 130 | 61 | 78 | 47 | 45 | 31 | 1 | 1
August | 800 | 73 | 130 | 35 | 85 | 26 | 30 | 14 | 1 | 0
September | 600 | 129 | [1] | [1] | 150 | 51 | 70 | 28 | 1 | 0
October | 75 | 32 | [1] | [1] | 65 | 28 | 75 | 26 | 4 | 0
November | 300 | 97 | [1] | [1] | 100 | 45 | 45 | 23 | 2 | 1
December | 680 | 135 | [1] | [1] | 180 | 61 | 100 | 46 | 10 | 4
----------+------+-----+-----+-----+-----+-----+------+-----+----+---
1908.
----------+------+-----+-----+-----+-----+-----+------+-----+----+---
January |2,100 | 202 | 340 | 73 | 250 | 82 | 160 | 65 | 20 | 7
February |3,000 | 302 | 300 | 52 | 150 | 52 | 75 | 32 | 7 | 4
March | 300 | 91 | 150 | 78 | 100 | 68 | 65 | 42 | 5 | 4
April | 75 | 23 | 65 | 41 | 37 | 27 | 26 | 20 | 3 | 2
May |2,000 | 172 | 130 | 48 | 85 | 37 | 50 | 20 | 1 | 1
June | 400 | 40 | 70 | 29 | 40 | 24 | 30 | 18 | 1 | 1
July |1,500 | 149 | ... | 74 | 170 | 44 | 75 | 15 | 0 | 0
August | 900 | 129 | 200 | [1] | 150 | 56 | 85 | 39 | 2 | 1
September | 75 | 24 | [1] | [1] | 50 | 19 | 35 | 18 | 0 | 0
October | 95 | 20 | [1] | [1] | 55 | 18 | 28 | 15 | 0 | 0
November | 24 | 11 | [1] | [1] | 20 | 11 | 19 | 10 | 0 | 0
December | 20 | 9 | 17 | 11 | 14 | 9 | 10 | 7 | 0 | 0
----------+------+-----+-----+-----+-----+-----+------+-----+----+---
1909.
----------+------+-----+-----+-----+-----+-----+------+-----+----+---
January | 400 | 72 | 95 | 32 | 60 | 23 | 25 | 16 | 4 | 1
February | 650 | 194 | 120 | 64 | 90 | 51 | 55 | 35 | 4 | 3
March | 250 | 51 | [1] | [1] | 90 | 44 | 60 | 37 | 8 | 4
April | 750 | 98 | [1] | [1] | 130 | 42 | 76 | 31 | 2 | 1
May | 480 | 57 | [1] | [1] | 30 | 19 | 30 | 12 | 2 | 1
June | 650 | 141 | [1] | [1] | 120 | 51 | 80 | 30 | 1 | 0
July | 400 | 48 | [1] | [1] | 215 | 46 | 120 | 35 | 2 | 1
August | 180 | 23 | [1] | [1] | 50 | 17 | 18 | 9 | 0 | 0
September | 26 | 16 | 24 | 14 | [1] | [1] | 25 | 6 | 0 | 0
October | 14 | 10 | 15 | 10 | 11 | 9 | 8 | 4 | 0 | 0
November | 11 | 9 | 11 | 8 | 10 | 8 | 6 | 4 | 0 | 0
December | 600 | 63 | 110 | 31 | 80 | 28 | 50 | 15 | 3 | 0
----------+------+-----+-----+-----+-----+-----+------+-----+----+---
1910.
----------+------+-----+-----+-----+-----+-----+------+-----+----+---
January |3,000 | 357 | 200 | 58 | 150 | 53 | 115 | 30 | 5 | 2
February |3,000 | 143 | 150 | 55 | 120 | 50 | 100 | 36 | 7 | 4
March | 210 | 36 | 100 | 35 | 95 | 38 | 100 | 43 | 9 | 5
April | 350 | 55 | 100 | 25 | 55 | 18 | 25 | 8 | 1 | 0[2]
May | 300 | 33 | 55 | 19 | 50 | 17 | 28 | 13 | 1 | 0[2]
June |1,500 | 246 | 180 | 42 | 110 | 37 | 50 | 16 | 1 | 0[2]
----------+------+-----+-----+-----+-----+-----+------+-----+----+---
Fiscal years:
----------+------+-----+-----+-----+-----+-----+------+-----+----+---
1905-06[2]|1,750 | 133 | 500 | 70 | 450 | 47 | 180 | 31 | 20 | 5
1906-07 |1,530 | 114 | 250 | 46 | 150 | 37 | 250 | 29 | 13 | 2
1907-08 |3,000 | 117 | 340 | 53 | 250 | 45 | 160 | 31 | 20 | 2
1908-09 |1,500 | 79 | 200 | 50 | 170 | 32 | 85 | 22 | 8 | 1
1909-10 |2,100 | 86 | 200 | 30 | 215 | 29 | 120 | 18 | 9 | 1
==========+======+=====+=====+=====+=====+=====+======+=====+====+=====
[Footnote 1: Reservoirs out of service.]
[Footnote 2: October to June 30th.]
~Table 4--Bacteria.~
Averages by Months.
=============+=======================================================
| ~Reservoirs:~
+----------+----------+----------+-------------+--------
Month. | | | | |
|Dalecarlia|Dalecarlia|Georgetown|McMillan Park|Filtered
| Inlet. | Outlet. | Outlet. | Outlet. | water.
-------------+----------+----------+----------+-------------+--------
1905.
-------------+----------+----------+----------+-------------+--------
October | ... | ... | ... | 210 | 80
November | ... | ... | ... | 150 | 27
December | ... | 15,500 | ... | 3,800 | 60
-------------+----------+----------+----------+-------------+--------
1906.
-------------+----------+----------+----------+-------------+--------
January | ... | 2,800 | ... | 1,500 | 39
February | 2,900 | 4,100 | 1,800 | 550 | 16
March | 1,800 | 1,100 | 900 | 650 | 19
April | 3,300 | 1,700 | 700 | 400 | 22
May | 425 | 210 | 95 | 65 | 17
June | 7,900 | 4,600 | 325 | 220 | 17
July | 13,500 | 600 | 475 | 160 | 26
August | 8,700 | 1,100 | 1,200 | 190 | 14
September | 425 | 250 | 140 | 135 | 14
October | 2,300 | 950 | 650 | 270 | 16
November | 1,800 | 1,100 | 1,200 | 220 | 12
December | 6,900 | 3,800 | 3,600 | 700 | 45
-------------+----------+----------+----------+-------------+--------
1907.
-------------+----------+----------+----------+-------------+--------
January | 4,400 | 2,400 | 2,200 | 950 | 70
February | 1,000 | 950 | 1,000 | 700 | 45
March | 11,500 | 8,300 | 7,200 | 3,600 | 65
April | 3,700 | 2,100 | 1,400 | 475 | 21
May | 750 | 350 | 325 | 130 | 26
June | 2,300 | 1,000 | 600 | 100 | 18
July | 2,700 | 575 | 350 | 160 | 17
August | 3,000 | 275 | 425 | 80 | 17
September | 6,200 | [1] | 1,900 | 230 | 32
October | 1,400 | [1] | 950 | 275 | 27
November | 8,900 | [1] | 6,600 | 1,500 | 27
December | 16,000 | [1] | 9,600 | 4,300 | 190
-------------+----------+----------+----------+-------------+--------
1908.
-------------+----------+----------+----------+-------------+--------
January | 11,000 | 8,700 | 9,400 | 3,700 | 190
February | 11,500 | 6,000 | 5,000 | 2,800 | 75
March | 4,600 | 4,000 | 2,900 | 1,300 | 30
April | 700 | 450 | 250 | 120 | 13
May | 9,500 | 1,100 | 650 | 325 | 17
June | 750 | 120 | 110 | 95 | 12
July | 4,900 | ... | 400 | 150 | 8
August | 1,600 | 325 | 300 | 100 | 12
September | 325 | [1] | 200 | 80 | 11
October | 375 | [1] | 325 | 140 | 8
November | 550 | [1] | 300 | 200 | 12
December | 800 | 750 | 375 | 170 | 23
-------------+----------+----------+----------+-------------+--------
1909.
-------------+----------+----------+----------+-------------+--------
January | 11,000 | 2,700 | 1,600 | 700 | 31
February | 8,000 | 3,500 | 2,400 | 1,300 | 60
March | 3,800 | [1] | 2,600 | 1,000 | 39
April | 2,200 | [1] | 1,400 | 550 | 12
May | 900 | [1] | 350 | 140 | 16
June | 3,400 | [1] | 1,200 | 170 | 21
July | 550 | [1] | 500 | 250 | 33
August | 400 | [1] | 325 | 55 | 18
September | 325 | 240 | [1] | 70 | 18
October | 350 | 275 | 250 | 130 | 20
November | 600 | 500 | 500 | 180 | 13
December | 21,000 | 9,100 | 5,900 | 4,500 | 250
-------------+----------+----------+----------+-------------+--------
1910.
-------------+----------+----------+----------+-------------+--------
January | 76,000 | 78,000 | 88,000 | 52,000 | 800
February | 45,000 | 35,500 | 31,000 | 17,500 | 350
March | 9,900 | 7,600 | 7,400 | 4,800 | 80
April | 7,900 | 4,100 | 3,500 | 650 | 29
May | 1,230 | 810 | 830 | 448 | 28
June | 3,660 | 930 | 800 | 324 | 27
-------------+----------+----------+----------+-------------+--------
Fiscal years:
-------------+----------+----------+----------+-------------+--------
1905-06 | 3,300[2]| 4,300[3]| 750[4]| 850[2]| 33[2]
1906-07 | 4,900 | 1,900 | 1,700 | 650 | 31
1907-08 | 6,360 | 2,700 | 2,900 | 1,300 | 55
1908-09 | 3,400 | 2,000 | 950 | 400 | 21
1909-10 | 14,300 | 13,900 | 10,900 | 6,890 | 143
=============+==========+==========+==========+=============+========
[Footnote 1: Reservoirs out of service.]
[Footnote 2: October to June 30th.]
[Footnote 3: December to June 30th.]
[Footnote 4: February to June 30th.]
~Table 5--Results of Tests for~ _Bacillus Coli_.
Percentage Positive.
=============+==============+==============+===============
| Great Falls, | Dalecarlia |
|or Dalecarlia | Reservoir | Georgetown
| Reservoir | Outlet. | Reservoir.
Month. | Inlet. | |
+----+----+----+----+----+----+----+----+-----
| 10 | 1 |0.1 | 10 | 1 |0.1 | 10 | 1 |0.1
|c.c.|c.c.|c.c.|c.c.|c.c.|c.c.|c.c.|c.c.|c.c.
-------------+----+----+----+----+----+----+----+----+-----
1906.
-------------+----+----+----+----+----+----+----+----+-----
January[1] |55.6|38.9|22.2|69.2|23.1| 7.7|56.0|40.0| 8.0
February |33.3|26.7| 6.7|26.1|17.4| 8.7|30.4|13.0| 4.4
March |50.0|12.5| 0|45.5|18.2| 0|20.8| 8.3| 0
April |72.2|33.3|16.7|95.5|50.0| 4.6|59.1|22.7| 4.6
May |20.0| 8.0| 4.0|20.0|12.0| 0| 7.8| 0| 0
June |57.7|38.5|19.2|40.0|32.0| 8.0|50.0|34.6| 0
July |65.0|50.0| 5.0|60.0|25.0|10.0|15.0| 5.0| 5.0
August |84.6|69.2|61.5|88.5|65.4|34.6|80.0|57.7|23.1
September |50.0|10.0| 0|30.0|10.0|10.0|40.0|10.0| 0
October |60.0|30.0|10.0|55.5|33.3| 0|80.0|60.0|20.0
November |37.5| 0| 0|25.0|12.5|12.5|37.5|25.0| 0
December |55.5|44.5| 0|66.7|44.5|22.2|66.7|22.2| 0
-------------+----+----+----+----+----+----+----+----+-----
1907.
-------------+----+----+----+----+----+----+----+----+-----
January |77.8|33.3|22.2|66.7|33.3| 0|55.5|55.5|22.2
February |37.5|25.0| 0|12.5| 0| 0|37.5|12.5| 0
March |87.5|50.0| 0|75.0|37.5| 0|50.0|25.0| 0
April |44.5|11.1|11.1|66.7|22.2|11.1|77.8|11.1|11.1
May |91.3|65.2|17.4|88.9|33.3| 0|87.5|50.0|12.5
June |80.0|68.0|24.0|87.5|62.5| 0|66.7|44.5|11.1
July |42.3|30.8|19.2|25.0|12.5| 0|22.2|22.2| 0
August |48.1|29.6| 3.7|33.3|16.7|16.7|36.4|18.2| 0
September |62.5|54.1|25.0| ...| ...| ...|41.7|33.3|16.7
October |51.9|40.8| 7.4| ...| ...| ...|53.3|40.0| 6.7
November |80.0|64.0|24.0| ...| ...| ...|72.7|54.5| 0
December |56.0|48.0|16.0| ...| ...| ...|46.2|38.5| 7.7
-------------+----+----+----+----+----+----+----+----+-----
1908.
-------------+----+----+----+----+----+----+----+----+-----
January |46.2|30.8|15.4|50.0|12.5| 0|33.3| 0| 0
February |12.5| 0| 0|25.0| 0| 0|12.5| 0| 0
March |38.5|19.2| 7.7|44.4|11.1| 0|11.1| 0| 0
April |15.4| 7.7| 0| 0| 0| 0| 0| 0| 0
May |76.0|52.0|40.0|87.5|50.0|12.5|33.3|22.2| 0
June | 7.7| 0| 0| 0| 0| 0|11.1| 0| 0
July |26.9|15.4|11.5|22.2|22.2| 0|11.1| 0| 0
August |46.2|26.9| 3.9|44.4|33.3| 0|62.5|25.0|12.5
September |20.0| 8.0| 4.0|42.9|28.6| 1.4|22.2|11.1| 0
October |18.4| 3.7| 0| 0| 0| 0| 9.1| 0| 0
November |13.0| 0| 0|28.6| 0| 0|11.1| 0| 0
December |11.5| 7.7| 3.8| 0| 0| 0|12.5| 0| 0
-------------+----+----+----+----+----+----+----+----+-----
1909.
-------------+----+----+----+----+----+----+----+----+-----
January |12.0| 8.0| 0|30.0|10.0| 0| 0| 0| 0
February |52.1|47.8|47.8|28.6|14.3| 0|37.5| 0| 0
March |69.4|34.6| 3.8|50.0|25.0| 0|44.5|11.1| 0
April |42.3|15.4| 3.9|33.3|22.2|11.1|44.4|22.2|11.1
May |88.4|26.1| 4.3|50.0|12.5| 0|33.3| 0| 0
June |85.0|60.0|25.0|60.0|40.0|10.0|44.4|33.3|11.1
July |34.8| 8.7| 4.4| ...| ...| ...|33.3|11.1| 0
August |50.0|15.4| 7.7| ...| ...| ...|40.0|10.0| 0
September |43.5|21.8| 8.7|25.0|25.0|12.5| 0| 0| 0
October |36.4|13.6| 0|18.2| 0| 0| 0| 0| 0
November | 4.5| 0| 0|10.0| 0| 0| 0| 0| 0
December |38.5|23.1| 7.7|36.4|36.4|18.2|33.3|22.2|11.1
-------------+----+----+----+----+----+----+----+----+-----
1910.
-------------+----+----+----+----+----+----+----+----+-----
January |72.0|48.0|24.0|44.5|33.3|11.1|75.0|25.0| 0
February |47.8|43.5|17.4|63.2|21.1| 5.3|40.0|30.0| 5.0
March |33.3|14.8| 0|30.8|11.1| 3.7|29.6|22.2| 7.4
April |41.7|33.3|20.8|40.0|32.0|16.0|38.5|23.1|15.4
May |47.8|17.4| 0|52.0|20.0| 0|36.0|16.0| 4.0
June |95.5|86.4|31.8|80.8|46.2|19.2|64.0|28.0| 8.0
-------------+----+----+----+----+----+----+----+----+----
Fiscal years:
-------------+----+----+----+----+----+----+----+----+-----
1905-06 |35.2|19.4|9.3 |0.0 |3.2 |5.2 |6.4 |4.9 |1.7
1906-07 |61.5|43.6|9.2 |7.7 |9.2 |2.3 |1.1 |9.8 |0.7
1907-08 |44.6|31.3|3.0 |2.3 |2.3 |3.1 |4.4 |2.1 |4.1
1908-09 |38.9|20.3|8.4 |0.0 |5.0 | 0 |7.4 |8.5 |2.8
1909-10 |45.5|26.9|0.1 |5.3 |4.0 |8.8 |7.9 |9.8 |6.2
=============+====+====+====+====+====+====+====+====+=====
=============+==============+=========+==========
|McMillan Park |Filtered-|Tap water
| Reservoir | water |from var-
| (applied | reser- |ious parts
Month. | water). | voir. |of city.
+----+----+----+----+----+----+-----
| 10 | 1 |0.1 | 10 | 1 | 10 | 1
|c.c.|c.c.|c.c.|c.c.|c.c.|c.c.|c.c.
-------------+----+----+----+----+----+----+-----
1906.
-------------+----+----+----+----+----+----+-----
January[1] |55.6|22.2| 0 | 7.2| 0| ...| ...
February | 8.3| 4.2| 0 | 0| 0| ...| ...
March |18.5| 7.4|3.7 | 0| 0| 0| 0
April |32.0| 8.0| 0 | 4.0| 0| 0| 0
May | 0| 0| 0 | 0| 0| 0| 0
June |23.1| 7.7|3.8 | 0| 0| 3.1| 0
July | 9.5| 0| 0 | 4.8| 0| ...| ...
August |63.0|33.3| 0 | 7.4| 3.7|11.9| 5.1
September |32.0|12.0| 0 | 8.0| 0| 3.1| 0
October |48.1|22.2|3.7 | 3.7| 0|13.0| 3.7
November |20.0|12.0| 0 | 8.0| 0| 0| 0
December |20.8| 8.3|4.2 |16.7| 8.3| 7.5| 0
-------------+----+----+----+----+----+----+-----
1907.
-------------+----+----+----+----+----+----+-----
January |69.3|34.6|3.8 |19.2|11.5|14.0| 0
February |17.4| 4.4| 0 | 0| 0| 2.9| 0
March |30.8| 7.7| 0 | 0| 0| 2.1| 0
April |46.1|19.2|3.8 | 3.8| 0| 3.2| 0
May |23.1| 0| 0 | 0| 0| 1.4| 0
June |40.0| 8.0| 0 | 0| 0| 0| 0
July | 3.8| 0| 0 | 0| 0| 1.4| 1.4
August |14.8| 3.7| 0 | 0| 0| 0| 0
September |16.0| 4.0| 0 | 4.0| 0| 1.7| 0
October |38.7|25.8|9.7 | 6.5| 0|12.5| 2.8
November |58.6|17.3|3.5 | 0| 0| 4.9| 0
December |45.2|29.0| 0 |19.3| 3.2|12.9| 4.3
-------------+----+----+----+----+----+----+-----
1908.
-------------+----+----+----+----+----+----+-----
January |22.6| 9.7|3.2 | 3.2| 0| 1.9| 1.9
February | 0| 0| 0 | 0| 0| 0| 0
March | 9.7| 0| 0 | 0| 0| 0| 0
April | 6.7| 3.3| 0 | 0| 0| 0| 0
May |45.1|16.2| 0 | 0| 0| 0| 0
June | 0| 0| 0 | 0| 0| 0| 0
July | 6.4| 6.4| 0 | 0| 0| 0| 0
August |12.9| 3.2| 0 | 0| 0| 1.6| 0
September |16.7|10.0| 0 | 0| 0| 4.3| 0
October | 9.7| 6.4|3.2 | 0| 0| 0| 0
November | 6.6| 0| 0 | 0| 0| 0| 0
December | 3.2| 0| 0 | 0| 0| 0| 0
-------------+----+----+----+----+----+----+-----
1909.
-------------+----+----+----+----+----+----+-----
January | 3.2| 3.2| 0 | 3.2| 0| 0| 0
February | 7.1| 3.6|3.6 | 0| 0| 3.4| 3.4
March |32.3|19.4|3.2 | 6.5| 0| 2.8| 1.4
April |36.6|10.0| 0 | 0| 0| 0| 0
May |12.9| 3.2| 0 | 0| 0| 0| 0
June |53.3|20.0| 0 | 0| 0| 1.4| 0
July |25.8|12.9| 0| 0| 0| 0| 0
August |22.6| 6.5| 3.2| 0| 0| 0| 0
September |13.3| 3.3| 0| 0| 0| 0| 0
October | 3.2| 0| 0| 0| 0| 0| 0
November | 0| 0| 0| 0| 0| 0| 0
December |29.0|22.6| 0| 9.7| 6.5| 7.3| 1.5
-------------+----+----+----+----+----+----+-----
1910.
-------------+----+----+----+----+----+----+-----
January |61.3|35.5|9.7 | 5.8| 3.2|15.9| 3.2
February |32.2| 7.1| 0 | 3.6| 0| 0| 0
March |12.9| 3.2| 0 | 0| 0| 0| 0
April |23.3|13.3| 0 | 0| 0| 0| 0
May |16.1|12.9| 0 | 0| 0| 0| 0
June |43.3| 6.7| 0 | 0| 0| 1.4| 0
-------------+----+----+----+----+----+----+-----
Fiscal years:
-------------+----+----+----+----+----+----+-----
1905-06 |4.3 |8.3 |.8 | .3| 1.8| 1.3| 0
1906-07 |2.5 |3.0 |.4 | .5| 2.1| 5.4| 1.0
1907-08 |2.2 |9.4 |.4 | .8| 0.3| 3.1| 0.9
1908-09 |6.7 |7.1 |.8 | .8| 0| 1.2| 0.4
1909-10 |3.6 |0.4 |.1 | .3| 0.8| 2.2| 0.4
=============+====+====+====+====+====+====+=====
[Footnote 1: Presumptive tests.]
~Table 6--Summary of Sanitary Chemicals Analyses of Weekly
Samples, July 1st, 1909, to June 30th, 1910.~
(Results in Parts per Million.)
Columns:
A - Turbidity[1]
B - Free
C - Albuminoid
D - Total
E - Nitrites
F - Nitrates
G - Hardness
H - Alkalinity
I - Chlorine
(_A_) ~Maximum.~
====================+=====+=================+===========+=====+=====+====
| | Ammonia. | Nitrogen | | |
| | | as: | | |
Reservoirs. | A +-----+-----+-----+-----------+ G | H | I
| | B | C | D | E | F | | |
--------------------+-----+-----+-----+-----+------+----+-----+-----+----
Dalecarlia inlet |2,100|0.034|0.264|0.280|0.0070|0.45|120.0|106.0|5.4
Dalecarlia outlet[2]| 200|0.034|0.180|0.206|0.0050|0.70|115.0|105.8|5.7
Georgetown outlet[3]| 215|0.030|0.182|0.182|0.0060|0.60|115.0|105.0|4.9
McMillan Park outlet| 120|0.028|0.126|0.154|0.0060|0.65|118.0|104.4|4.2
Filtered water | 9|0.016|0.078|0.086|0.0010|0.70|119.5|106.3|4.5
--------------------+-----+-----+-----+-----+------+----+-----+-----+---
~Table 6~--(_Continued._)
(_B_) ~Minimum.~
====================+=====+=================+===========+=====+=====+====
| | Ammonia. | Nitrogen | | |
| | | as: | | |
Reservoirs. | A +-----+-----+-----+-----------+ G | H | I
| | B | C | D | E | F | | |
--------------------+-----+-----+-----+-----+------+----+-----+-----+----
Dalecarlia inlet | 7|0.000|0.016|0.016|0.0000|0.00| 52.9| 39.5| 1.0
Dalecarlia outlet[2]| 7|0.000|0.040|0.040|0.0000|0.00| 54.3| 38.2| 0.9
Georgetown outlet[3]| 7|0.000|0.044|0.044|0.0000|0.00| 51.4| 40.6| 0.7
McMillan Park outlet| 2|0.000|0.010|0.010|0.0010|0.00| 51.4| 38.5| 0.2
Filtered water | 0|0.000|0.000|0.000|0.0000|0.00| 52.9| 40.3| 0.4
--------------------+-----+-----+-----+-----+------+----+-----+-----+----
~Table 6~--(_Continued._)
(_C_) ~Average.~
====================+=====+=================+===========+=====+=====+====
| | Ammonia. | Nitrogen | | |
| | | as: | | |
Reservoirs. | A +-----+-----+-----+-----------+ G | H | I
| | B | C | D | E | F | | |
--------------------+-----+-----+-----+-----+------+----+-----+-----+----
Dalecarlia inlet | 86 |0.006|0.167|0.113|0.0027|0.19| 93.2| 81.4| 2.9
Dalecarlia outlet[2]| 30 |0.008|0.106|0.114|0.0023|0.18| 95.5| 79.5| 3.4
Georgetown outlet[3]| 29 |0.005|0.101|0.106|0.0027|0.18| 93.4| 80.9| 2.9
McMillan Park outlet| 18 |0.004|0.077|0.081|0.0027|0.17| 94.0| 83.0| 2.7
Filtered water | 1 |0.002|0.027|0.029|0.0000|0.19| 94.9| 84.0| 2.8
====================+=====+=====+=====+=====+======+====+=====+=====+====
[Footnote 1: Summary of daily samples of water.]
[Footnote 2: Reservoir out of service from July 1st to September
13th, 1909.]
[Footnote 3: Reservoir out of service from September 10th to
October 4th, 1909.]
No chemical determinations were made during February, March, April,
and May, 1910, on account of the rearrangement of the laboratory
and equipment.
~Table 7--Daily Results at Pumping Station~.
(_A_)
=============+===================================+========+==========
| ~Million gallons pumped:~ | | Pressure
+-----------------+-----------------+ | at sand-
| | | Lift | washer
| To filters. | To sand washers.| to | pumps,
Month. | | |filters.| per
|-----+-----+-----+-----+-----+-----| | square
| Max.| Min.|Ave. | Max.| Min.| Ave.| | inch.
-------------+-----+-----+-----+-----+-----+-----+--------+----------
1909.
-------------+-----+-----+-----+-----+-----+-----+--------+----------
July |76.16|57.65|64.05|1.140|0.298|0.730| 24.18 | 110.0
August |69.31|54.44|61.42|0.629|0.157|0.441| 22.18 | 110.0
September |66.02|52.82|69.32|0.831|0.207|0.572| 22.26 | 110.0
October |78.50|48.12|59.18|0.761|0.060|0.467| 21.84 | 110.0
November |64.92|49.83|55.25|0.468|0.141|0.272| 20.49 | 110.0
December |67.83|48.32|56.77|0.307|0.039|0.174| 20.54 | 110.0
-------------+-----+-----+-----+-----+-----+-----+--------+----------
1910.
-------------+-----+-----+-----+-----+-----+-----+--------+----------
January |70.04|51.02|62.49|0.499|0.008|0.156| 22.43 | 110.0
February |70.79|55.19|60.28|0.284|0.041|0.173| 21.44 | 112.3
March |59.11|51.64|56.04|0.409|0.063|0.171| 19.76 | 120.0
April |66.53|53.79|58.32|0.715|0.167|0.474| 20.78 | 120.0
May |61.93|54.55|57.76|0.525|0.059|0.251| 20.30 | 120.0
June |70.49|50.42|58.37|0.281|0.124|0.207| 21.19 | 117.3
-------------+-----+-----+-----+-----+-----+-----+--------+----------
Fiscal years:
-------------+-----+-----+-----+-----+-----+-----+--------+----------
1909-10 |78.50|48.12|59.19|1.140|0.008|0.373| 21.45 | 113.3
-------------+-----+-----+-----+-----+-----+-----+--------+----------
1905-06[1] |80.59|57.18|66.07|2.062|0.089|0.747| 21.71 | 107.4
1906-07 |80.29|57.44|66.89|2.120|0.023|0.580| 21.60 | 120.8
1907-08 |80.38|54.35|64.91|0.735|0.017|0.347| 22.20 | 125.0
1908-09 |78.93|47.83|61.47|0.875|0.060|0.453| 22.52 | 122.3
-------------+-----+-----+-----+-----+-----+-----+--------+----------
=============+==============+===============
|~Coal consumed|~Station duty,
| per day in |per 100 lb. of
Month. | tons.~ |coal consumed.~
|----+----+----+----+----+-----
|Max.|Min.|Ave.|Max.|Min.|Ave.
-------------+----+----+----+----+----+-----
1909.
-------------+----+----+----+----+----+-----
July |13.4| 8.4|10.8|67.8|52.3|61.4
August |12.4| 8.0|10.1|64.2|49.5|56.6
September |12.7| 8.7|10.5|61.0|48.9|55.1
October |13.4| 8.0|10.3|59.6|49.1|53.6
November |11.3| 7.9| 9.2|55.6|45.7|51.1
December |10.3| 8.5| 9.5|61.0|45.4|50.4
-------------+----+----+----+----+----+-----
1910.
-------------+----+----+----+----+----+-----
January |12.7| 9.1|10.4|59.6|49.8|54.9
February |12.3| 8.7|10.2|57.4|44.8|51.5
March |10.5| 7.8| 9.2|53.2|45.2|49.8
April |11.1| 8.1| 9.7|58.7|47.2|53.7
May |10.1| 7.4| 8.8|60.7|48.1|54.9
June |12.3| 7.4| 9.1|60.1|49.9|54.4
-------------+----+----+----+----+----+-----
Fiscal years:
-------------+----+----+----+----+----+-----
1909-10 |13.4| 7.4| 9.8|67.8|44.8|54.0
-------------+----+----+----+----+----+----
1905-06[1] |14.8| 6.4| 8.9|79.6|48.2|62.8
1906-07 |15.0| 7.0|10.0|71.6|46.5|58.6
1907-08 |12.0| 7.2|9.6 |70.7|51.3|60.3
1908-09 |13.2| 7.0|10.0|74.0|45.7|57.7
-------------+----+----+----+----+----+----
[Footnote 1: Raw water shut off from city supply on October 5th.]
~Table 7~--(_Continued._)
(_B_)
========+=======================+=========+==========+=============
| | | Duty per | Cost of
| | | 100 lb. | coal per
Fiscal | Name of coal used. |Cost per | of coal |1,000,000 ft-
Year. | | ton. | consumed.|lb. of work
| | | | performed
--------+-----------------------+---------+----------+-------------
1905-06 |George's Creek Big Vein| $3.34 | 62.8 | $0.00238
1906-07 |George's Creek Big Vein| 3.43 | 58.6 | 0.00261
1907-08 |George's Creek Big Vein| 3.75 | 60.3 | 0.00278
1908-09 |Orenda | 3.47 | 57.7 | 0.00268
1909-10 |Orenda |[1]3.15 | 54.0 | 0.00255
========+=======================+=========+==========+=============
[Footnote 1: Corrected for increase or decrease in ash and British
thermal units, as determined by United States Geological Survey.]
~Table 8--Average Consumption of Water for
Twenty-four Hours, Per Million Gallons.~
==========+================================================
| ~Fiscal years.~
Month. +-----+-----+-----+-----+-----+-----+-----+------
|1903.|1904.|1905.|1906.|1907.|1908.|1909.|1910.
----------+-----+-----+-----+-----+-----+-----+-----+------
July |59.80|61.50|63.20|69.80|69.18|68.64|71.08|64.05
August |59.00|59.70|67.70|71.40|68.03|67.74|68.14|61.42
September |56.50|61.10|67.90|71.30|69.82|68.93|65.83|60.32
October |58.70|59.10|63.90|68.40|69.14|66.46|65.89|59.18
November |54.70|58.60|62.10|66.10|65.51|61.54|60.06|55.25
December |60.70|60.10|70.30|67.20|65.71|62.29|57.99|56.77
January |60.10|65.30|75.10|65.30|67.62|63.36|57.72|62.49
February |59.30|67.80|86.00|68.70|74.68|68.17|55.42|60.28
March |55.30|60.00|67.60|64.30|64.23|59.63|55.31|56.04
April |55.10|57.20|63.10|62.70|63.45|61.51|58.19|58.32
May |57.70|60.80|66.30|65.60|62.47|62.96|59.25|57.76
June |59.50|62.30|70.60|67.80|63.53|67.96|60.12|58.37
----------+-----+-----+-----+-----+-----+-----+-----+------
Average |58.03|61.10|68.70|67.40|66.90|64.91|61.47|59.19
==========+=====+=====+=====+=====+=====+=====+=====+======
The length of runs, depth of scraping, etc., after the scraping or
raking, are shown in Tables 10 and 11.
_Sand Handling._--For the first three years of operation, the sand
was carried from the sand bins in carts and dumped through the
numerous manholes of the filters on chutes which could be revolved
in various directions, in order to facilitate the spreading of the
sand evenly over the surface of the filter.
About a year ago, however, this method was changed, by substituting
sand ejectors for the carts. By this method, an ejector is either
attached to, or placed directly under, the outlet gate of the sand
bin, the gate is opened, and the ejector is started. From this
ejector, the sand is carried back through the line of 4-in. fixed
pipe, and one or more lengths of 3-in. hose, to the point of
discharge in the filter bed which is being re-sanded.
~Table 9.~
Columns:
A - July.
B - August.
C - September.
D - October.
E - November.
F - December.
G - January.
H - February.
I - March.
J - April.
K - May.
L - June.
(_A_) ~Number of Deaths from Typhoid Fever, by Months, in the
District of Columbia for the Last Fourteen Fiscal Years.~
==========+====+====+====+====+====+====+===+===+===+===+===+===+======
Fiscal | | | | | | | | | | | | |
year. | A | B | C | D | E | F | G | H | I | J | K | L |Total.
----------+----+----+----+----+----+----+---+---+---+---+---+---+------
1896-97 | 8 |15 |25 |25 |18 |16 |13 | 4 | 4 | 4 | 6 | 9 | 147
1897-98 |10 |16 |18 |10 | 9 |18 | 8 | 4 | 2 | 9 | 6 |20 | 130
1898-99 |24 |22 |22 |28 |21 |16 |10 | 4 | 7 | 6 | 3 | 6 | 169
1899-1900 | 9 |38 |30 |28 |27 |26 |17 | 6 | 8 |10 | 5 |12 | 193
1901-02 |16 |33 |28 |21 |22 |16 |19 | 8 |12 | 9 |13 | 9 | 206
1902-03 |21 |39 |25 |32 |19 |20 | 9 | 5 | 9 | 6 | 6 | 3 | 194
1903-04 |17 |26 |18 |19 | 8 |14 | 5 | 5 | 6 |10 | 8 | 8 | 144
1904-05 |16 |22 |25 |14 |11 | 9 |11 | 1 | 5 | 7 | 1 | 3 | 125
1905-06[1]|15 |30 |23 |26 |14 | 6 | 6 | 4 | 5 | 4 |10 | 9 | 152
1906-07 |21 |32 |21 |25 |17 | 4 | 7 | 6 | 4 | 6 | 7 | 2 | 152
1907-08 |10 |18 |17 |19 |11 | 7 | 4 | 1 | 1 | 8 | 8 | 3 | 107
1908-09 |15 |13 |23 |17 |16 |13 |16 | 8 | 3 | 8 | 7 | 7 | 146
1909-10 |12 |12 |17 |12 |12 | 2 | 3 | 4 | 7 | 5 | 5 | 4 | 95
----------+----+----+----+----+----+----+---+---+---+---+---+---+------
Average |15.3|25.5|22.9|21.5|16.6|13.1|9.6|4.4|5.8|6.7|6.4|7.5|155.4
----------+----+----+----+----+----+----+---+---+---+---+---+---+------
~Table 9~--(_Continued._)
Columns:
A - July.
B - August.
C - September.
D - October.
E - November.
F - December.
G - January.
H - February.
I - March.
J - April.
K - May.
L - June.
M - Annual death rate.
(_B_) ~Number of Deaths from Typhoid Fever Reduced to
Death Rates per 100,000 Inhabitants per Year.~
==========+===+===+===+===+===+===+===+===+===+===+===+===+====
Fiscal | | | | | | | | | | | | |
year. | A | B | C | D | E | F | G | H | I | J | K | L | M
----------+---+---+---+---+---+---+---+---+---+---+---+---+----
1896-97 | 35| 65|109|109| 78| 70| 56| 17| 17| 17| 26| 39| 53
1897-98 | 43| 69| 78| 43| 39| 78| 31| 17| 8| 38| 25| 85| 46
1898-99 |102| 93| 93|119| 89| 68| 42| 17| 29| 25| 12| 26| 59
1899-1900 | 37|158|125|116|112|108| 69| 24| 33| 41| 20| 49| 74
1900-01 | 82|167|118|102|114| 69| 28| 8| 32| 8| 16| 40| 65
1901-02 | 64|132|112| 84| 88| 64| 75| 31| 47| 35| 51| 35| 68
1902-03 | 83|153| 98|126| 75| 79| 35| 19| 35| 23| 23| 12| 63
1903-04 | 66|100| 69| 73| 31| 54| 19| 19| 23| 38| 30| 30| 46
1904-05 | 61| 83| 95| 53| 42| 34| 41| 4| 19| 26| 4| 11| 39
1905-06 | 56|111| 85| 97| 52| 22| 22| 15| 18| 15| 36| 33| 47
1906-07 | 69|105| 69| 82| 56| 13| 24| 20| 13| 20| 24| 7| 42
1907-08 | 35| 64| 60| 67| 39| 25| 14| 4| 4| 28| 28| 11| 32
1908-09 | 53| 45| 80| 60| 56| 45| 56| 28| 10| 28| 24| 24| 43
1909-10 | 42| 42| 60| 42| 42| 7| 11| 14| 24| 17| 17| 14| 28
----------+---+---+---+---+---+---+---+---+---+---+---+---+----
Average | | | | | | | | | | | | |
monthly | 59| 99| 89| 84| 65| 53| 38| 24| 22| 26| 24| 30|...
death | | | | | | | | | | | | |
rate. | | | | | | | | | | | | |
==========+===+===+===+===+===+===+===+===+===+===+===+===+====
[Footnote 1: Filtered water supplied since October, 1905.]
[Illustration: ~Figure 3--Washington Aqueduct, D. C., Filteration
Plant. Sand Handling, System.~]
[Illustration: ~Figure 4--Washington Aqueduct, D. C., Filtration
Plant. Washer Sand-Handling, System.~]
[Illustration: ~Figure 5--Washington Aqueduct, D. C., Filtration
Plant. Ejector Sand-Handling, System.~]
~Table 10--Periods of Operation, and Quantities Filtered.~
=============+=============+============================================
| Number of | ~Number of days since previous~:
| filter runs +---------------------+----------------------
|ended after: | Scraping. | Raking.
Month. +------+------+------+------+-------+-------+------+-------
|Scrap-| Rak- | Max. | Min. | Ave. | Max. | Min. | Ave.
| ing. | ing. | | | | | |
-------------+------+------+------+------+-------+-------+------+-------
1909.
-------------+------+------+------+------+-------+-------+------+-------
July | 14 | 0 | 89 | 44 | 67.4 | 0 | 0 | 0
August | 8 | 0 | 74 | 51 | 60.4 | 0 | 0 | 0
September | 13 | 0 | 98 | 53 | 68.3 | 0 | 0 | 0
October | 18 | 5 | 81 | 32 | 59.9 | 43 | 33 | 39.4
November | 8 | 2 | 79 | 44 | 53.4 | 47 | 37 | 42.0
December | 3 | 4 | 62 | 61 | 61.3 | 63 | 50 | 57.3
-------------+------+------+------+------+-------+-------+------+-------
1910.
-------------+------+------+------+------+-------+-------+------+-------
January | 9 | 4 | 95 | 79 | 88.0 | 88 | 72 | 77.0
February | 1 | 4 | 99 | 99 | 99.0 | 93 | 51 | 71.0
March | 3 | 4 | 120 | 110 | 113.7 | 108 | 101 | 104.3
April | 10 | 12 | 126 | 62 | 84.8 | 129 | 21 | 65.3
May | 3 | 2 | 86 | 38 | 69.7 | 55 | 32 | 43.5
June | 13 | 2 | 100 | 61 | 79.7 | 129 | 78 | 103.5
-------------+------+------+------+------+-------+-------+------+------
Year 1909-10 | 103 | 39 | 126 | 32 | 71.1 | 129 | 21 | 66.6
-------------+------+------+------+------+-------+-------+------+------
Fiscal years:| | | | | | | |
-------------+------+------+------+------+-------+-------+------+-------
1905-06 | 71 | 0 | 195 | 38 | 91.1 | 0 | 0 | 0
1906-07 | 101 | 4 | 199 | 24 | 77.0 | 32 | 14 | 21.7
1907-08 | 143 | 77 | 180 | 11 | 54.9 | 63 | 7 | 28.6
1908-09 | 128 | 50 | 135 | 11 | 49.9 | 93 | 13 | 34.2
=============+======+======+======+======+=======+=======+======+=======
=============+========================================================
| ~Million gallons filtered since previous:~
+--------------------------------------------------------
Month. | Scraping. | Raking.
+--------+--------+---------+--------+--------+----------
| Max. | Min. | Ave. | Max. | Min. | Ave.
-------------+--------+--------+---------+--------+--------+----------
1909.
-------------+--------+--------+---------+--------+--------+----------
July | 229.01 | 106.27 | 163.289 | 0 | 0 | 0
August | 175.54 | 124.94 | 152.581 | 0 | 0 | 0
September | 237.52 | 114.37 | 161.702 | 0 | 0 | 0
October | 206.09 | 78.78 | 132.359 | 96.50 | 71.51 | 82.708
November | 168.19 | 82.32 | 112.603 | 99.00 | 90.23 | 94.615
December | 135.77 | 128.33 | 132.647 | 144.35 | 106.11 | 125.940
-------------+--------+--------+---------+--------+--------+----------
1910.
-------------+--------+--------+---------+--------+--------+----------
January | 204.38 | 146.58 | 178.461 | 189.48 | 152.33 | 170.735
February | 205.73 | 205.73 | 205.730 | 192.98 | 118.85 | 158.890
March | 275.96 | 257.36 | 265.493 | 249.68 | 224.49 | 238.993
April | 295.96 | 104.13 | 181.972 | 307.57 | 45.22 | 142.448
May | 186.64 | 81.66 | 150.230 | 102.15 | 69.79 | 85.978
June | 213.70 | 130.85 | 171.059 | 181.25 | 167.84 | 174.540
-------------+--------+--------+---------+--------+--------+----------
Year 1909-10 | 295.96 | 81.66 | 159.151 | 307.57 | 45.22 | 143.832
-------------+--------+--------+---------+--------+--------+----------
Fiscal years:
-------------+--------+--------+---------+--------+--------+----------
1905-06 | 497.45 | 116.66 | 240.379 | 0 | 0 | 0
1906-07 | 466.12 | 69.76 | 220.693 | 103.28 | 32.13 | 76.870
1907-08 | 477.19 | 28.20 | 146.912 | 165.25 | 17.08 | 75.775
1908-09 | 298.08 | 39.26 | 125.617 | 244.19 | 41.41 | 88.439
=============+========+========+=========+========+========+===========