The Water Supply of the El Paso and Southwestern Railway from Carrizozo to Santa Rosa, N. Mex. | Page 8

a steady pressure are highly desirable. This doubtless
accounts to some extent for the extreme tightness of the wood pipe in
the pumping main.
Grade Lines.--The hydraulic grade lines, shown on Plate V, were laid
as best fitting the controlling elevations. The various diameters of pipe
were determined by Darcy's general formula, with C = 0.00033 for
wood and = 0.00066 for iron pipe, checking by Kutter's formula, with n
= 0.01 for wood and = 0.012 for iron. These coefficients were taken as
conservative and on the safe side, and such they proved to be. It was
desired that the line should carry not less than 5 sec-ft. to Nogal and
half as much beyond.
Velocities.--The pipe line from Bonito Creek to the Nogal Reservoir
affords excellent conditions for velocity and capacity measurements,
there being no distribution service from it. Beginning at the creek, it
consists of 12,700 ft. of 10-in. wood pipe, with a hydraulic grade of
0.03338, followed by 48,000 ft. of 16-in. wood pipe, with a hydraulic
grade of 0.0030625, ending on the south rim of the Nogal Reservoir.
There is an open stand-pipe where the two pipes and grades join.
When this section of the line was laid, the last car of 16-in. pipe was
late in arriving and, as it was desirable to get water into the reservoir as
soon as possible, 500 ft. of 10-in. pipe were laid in the lower part of the

16-in. line, near the reservoir, as indicated on Fig. 2, which shows the
hydraulic grades and the pipe diameters of this section of the line.
When the first two velocity measurements, of March 10th and 31st,
1908, described below, were made (after the line had been put into
service on February 20th, 1908), the 500 ft. of 10-in. pipe were still in
the 16-in. line, and the hydraulic grade was defined by the solid line,
ABCDE, Fig. 2.
When the third measurement, of May 12th, 1909, also described below,
was made, the 10-in. pipe had been replaced by 16-in. pipe, and the
hydraulic grade was defined by the solid line, ABE.
[Illustration: FIG. 2.]
The dotted line, AFE, is the approximate theoretical position which the
grade, ABCDE, should have assumed when the 500 ft. of 10-in. pipe
were taken out of the 16-in. line. On the contrary, it took the position of
the grade line, ABE.
During the interval between March, 1908, and May, 1909, the water
came to overflow from the stand-pipe at B, when the line was running
under full pressure, indicating an increase of capacity in the 10-in. pipe
greater than a corresponding increase in the 16-in. The alignment of the
10-in. line, vertically and horizontally, is more regular and uniform
than the 16-in. line. The latter has many abrupt curves and bends,
vertically and horizontally. It crosses nine sharp ridges and dips under
as many deep arroyos. This introduces a fixed element of frictional
resistance which does not decrease with the increasing smoothness of
the interior surface of wood pipe, and probably accounts for the higher
resistance of the 16-in. line.
From Fig. 2 it appears that, while the 10-in. line had an initial
coefficient of roughness slightly greater than 0.009 and now equal to it,
the 16-in. line had one equal at first but now slightly less than 0.01.
The line from Bonito Creek to Nogal Reservoir was to have a capacity
of 5 sec-ft. Referring to the profile, it was determined that for the

hydraulic grade of 33-1/3 ft. per 1000 ft., a 10-in. pipe was necessary,
and that a 16-in. pipe was required for the grade of 3 ft. per 1000 ft.
_Test No. 1_.--On March 10th, 1908, a quantity of bran was poured
into the upper end of the 10-in. pipe at A (Fig. 2), and the time of its
appearance at the lower end of the 16-in. pipe at E was noted. The time
was 3 hours and 50 min.
This gave:
Area of 10-in. pipe = 0.5454 sq. ft. " " 16 " " = 1.3960 " " Length " 10 "
" = 13,200 ft. " " 16 " " = 47,500 " Time, = 13,800 sec.
Let x = velocity of flow in 16-in. pipe, in feet per second, then 2.56 x =
velocity of flow in 10-in. pipe, in feet per second.
From which:
13,200 47,500 ------- + ------- = 13,800 2.56x x x = 3.805
and 2.56x = 9.740
The discharge is:
For the 16-in. pipe, 1.396 x 3.805 = 5.31 cu. ft. per sec.; and, for the
10-in. pipe, 0.5454 x 9.74 = 5.31 cu. ft. per sec.
The question arose as to whether or not the particles of bran in the
water traveled as fast as the water flowed. It was also desired to check