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Report on Okanagan Centre Irrigation District and Power Co.'s System, August 31, 1928 Latimer, F. H. Aug 31, 1928

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Report on Okanagan Centre Irrigation & Power
Co.'s System by F. H. Latimer, c.e.
*p-ip*t Penticton, B.C.,
August 31st. 1928.
J. L. Logie, Esq.,
Mngr. Okanagan Centre Irrig. & Power Co., Ltd.,
Okanagan Centre, B.C.
Sir:
At your request, I proceeded to Okanagan Centre on the 7th inst.
and examined on the ground the existing conditions where a slide had taken
place along the 22-inch Main about one quarter of a mile below the Intake.
The surface indications were that the movement extended for a distance of about 300 yards along the pipe line, the centre being near the watchman's cabin maintained by the Company close to the line. The heads as
read from the profile of this pipe, indicated a static pressure on this portion
of the line of only from 35 to 50 feet. Cracks or slips were to be seen
extending to a maximum of about 250 feet above the pipe line and nearly
opposite to the cabin. The greatest exposed slip surface was an almost
vertical bank slightly upstream and above the cabin, amounting to some 10
or 12 feet. Directly above this was also visible clear indications of an old
slip of almost equal extent.
The top and portions of the Main had been uncovered at the joints,
and, while a slight dampening could be seen at some of the joints, no indications of serious leaks could be found. Further up the line and across the
creek, some strong leaks were flowing near the air vent in a location where,
apparently, they have not done much harm up to the present, but otherwise
there were no signs of heavy leaks such as would be expected to cause so
large a slide. In addition to exposed surfaces at slips, many cracks were seen
up to two inches in width, so that, in addition to a sliding of the whole mass
towards the creek, a certain amount of settling or incipient toppling over of
the lower portion of the slide had taken place. A small stream of water
was flowing out of the foot of the slide down near the creek some fifty feet
below the cabin. Near the upstream end of tfee slide there has been a continuous, flow of water coming down a short "draw" which has been carried,
over the pipe in a wooden conduit. It was observed' that the waste from
this overflow had been out of repair for some time so that a cut had been
washed into the bank below the pipe line. In a situation of this kind,
where drainage is of so much importance, the overflow should be conveyed
down in pips, preferably, or in flume, till clear of the foot of the slope.
I was?informed that .there Was some evidence of movement in some
portions of the slide area towards the last of April of this- spring before the
Main had been filled.
On the following day (Aug. 8th) I examined the hills extending from"
the pipe line back for a distance of half a mile most of the land being open
range with scattering trees, continuing easterly to a point considerably beyond
the Intake. There are no valleys or marked water channels of any extent,
leading into the creek close to the slide, and none above the top of high
creek bank above the slide, so that, as far as surface indications go, there is
nothing to indicate any extraordinary stream of water, but there was noted some old ditches near to and more or less parallel to the top of the steep
creek bank which would lead surface drainage to finally discharge on slopes
draining into Clark's creek. These ditches nave become pretty well filled up
from natural causes through course of time. From this I would conclude
that at some former time, either from trouble already experienced or else
anticipated, these drainage ditches had been made to divert the surface, runoff
from going down the bank to the pipe line, possibly at the former ground
movement indicated by the slip bank near the cabin as already mentioned.
As a precaution, it would be advisable to keep these ditches in good working
condition, which can be easily done and at light cost. In a season such as
has been experienced in the Okanagan Valley from last Fall to this Spring
where the rainfall has been frequent and abnormally great and surface runoff
large from rains and melting snow, these cutoff ditches are almost essential.
But while surface water might be diverted from the pipe line to a very considerable extent, the long grassy slopes leading to the creek would absorb a
large amount of water, particularly when there has been so little frost in the
ground. This seepage water must necessarily appear, in time, wherever the
rock surface or other more or less impermeable material is reached and these
approach or appear at the surface. Even at this late date it was observed
that at a short distance below the top of bank above the cabin the "draw"
mentioned above divided into branches near its source, in both of which
were springs running small streams of water.
Summarizing, in the examination on the ground involved in the slide,
the following particular points: .were observed :-
All the joints in Main 'were uncovered.
The cover above the Main is, in general, only a few inches, so that
leaks of any consequence would show up by a discoloration of the
ground surface.
There were no signs of any leaks that could account for the stream
running out near the foot of the slide.
Comparatively few joints showed any discoloration.    Springs and
signs of considerable seepage from the upper bank of the creek are
evident.    A cutoff 'wall should be installed that "would divert the
'water more effectively from the springs above the pipe line, and the
water carried over clear of the Main and down to the creek.
From my study of the conditions and surroundings I consider it
clear that the main factor in causing this slide has been due to the unusual
weather conditions experienced since last Fall.
The rainfall has been more frequent and above the normal, causing
a large quannty to reach the steep slope on which the pipe line is laid, much
of this being seepage.
As for possible remedies. There is no possibility of improving the
position of the Main since the slide extends considerably above the hydraulic
gradient of the pipe. The pipe can not be moved to the south side of the
creek except at heavy cost, and would then be in a position more susceptible
to slides on portions of the line than where it now is. I would recommend
that, in addition to steps being taken to cut off and divert as much of the
seepage water above the line as already pointed out, the pipe be partly
uncovered, so that if any further motion takes place the pipe can acccrrmo-
date itself to changed conditions, acting as a beam, and possibly not break
or open a joint. Every joint also should be carefully examined and repaired
or replaced so that no water can escape into the bank from the pipe. From
inspection it would appear that it might be possible to re-align the pipe line
and secure an improved location for the upper two miles, which would be
less susceptible to trouble in operation than much of the present line but
this will require further investigation and surveys.
On August 15, I was requested to examine and report on a break in
the Main and washout situated towards the lower end of slide already discussed, the break being situated about 350 feet west of the watchman's
cabin, and determine the best method to follow in making repairs.
The length of break was found to be 132 feet of which about 100
feet of pipe could be salvaged. A considerable portion of the bank extending up to six or eight feet above the line had been washed out, the cut
extending down to the creek, the vertical depth from pipe to bottom of wash
varying from one to ten feet. From reports it seemed that the washout had
taken place early on the previous evening after an increased quantity of
water had been turned into the Main.
On the face of the cut the soil was darkened with moisture, which
extended out fan-shaped from below the ends of broken pipe, but did not
appear to be in any way saturated sufficiently to cause a slide, so tr^t it is
likely that some joint gave way, and was probably caused by the general
conditions above reviewed in the discussion on the slide.
After studying the ground, it appeared to me that a trestle was not
advisable since the materials for footings on the loose wash were too unstable,
skilled labor for trestle work was not immediately available, and there was
much risk of die cracked bank along the upper side of wash caving over on
to pipe and trestle if installed on old line, so I recommended taking up a
portion of the pipe from its present location and relaying it on a new and
higher benched surface above and around the wash, the total length thus
affected being 142 feet above the break and 197 feet below, making a total
of 471 feet to be relayed on the new alignment. The excavation for benches
or trench is not great and it permitted of the most simple and quickest
method of repair. -^H^k 1^^M^& sjwa$k 3*£$ ^
In follow'tag up the pipeline to the break I have noticed that Bridge
No. 3 is iri bad condition. This is one of the two bridges noted' in my
report in 1925 which pointed out that both bridges No. 3 and No. 4 were
in a very doubtful condition and should be rebuilt for the next season.
Bridge No. 4 has been temporarily strengthened withy intermediate posts but
No. 3 has sagged considerably and should be attended to at once.
As to Air Valve stated to have been placed at summit of pipe line
about poo feet west of Clark's creek, about Sta. 206, the tracing of profile
of line does not show any although one is indicated at the summit about Sta.
160 or y^ mile further west. If none can be found at the summit near Sta.
206, one should be installed as early as possible. This is necessary not only
to lessen possible water hammer if the pipe becomes empty from any cause
and is being refilled, but also to be able to secure the maximum capacity of
the pipe. Ordinarily, this section of the pipe should always be full excepting
from accumulation of air, unless emptied from the waste at Clark's creek or
as the result of leaks, since it is some 80 feet below the summit at Sta. 160.
In considering the general condition and operation of this supply
Main, I would refer again [to my former report in August, 1925, which
placed the estimated further life of the wood portion of 22-inch main as
about 14 years (or 11 years from now) assuming some limited replacements
of pipe particularly under low heads, and collar renewals. The latter is particularly advisable since all leaks that have occurred so far as my information goes, have been due to decay around the collars. Owing to the location tif
line for first mile being, to a large extent, on steep side hill, leaks that start
may soon become serious, and cause much damage on the ground as well as
shut off the supply from the distributing system.
In this connection one must realize that the time is at hand when
considerable repairs should be made to the Main, aside from repairs or replacements on the distribution system, which brings one to the question of
adequate rates to take care of operation and maintenance, the latter being
considered as comprising in general, repairs of a substantial nature and replacements. It will be seen from the Auditor's reports, for example, taking
the last complete year to Dec. 31st, 1927, would be at the nominal rates set
per ac. ft. demanded :
1927. 518.32 ac.     at    $5.60 '*~j$sk: $2,902.59w   ^gfk.;$i
807.05 ac.    at      7.10        -- 5,730^05-,
489.65 ac.    at      8.60        - 4,210.89
1,815.02 $12,843.63
If the rate had been as I understand was formerly agreed*'"upon at a meeting
between the lotholders and the company representatives, the amount of rates
on same demand would be :
518.32 ac.    at $ 6.00 -      --        $3,109.92
:'80^.05 at      9.00        - 7^263.45
489.65 at    12.00        - 5,875.80
$16,249.17
or a difference of $3,405.54.
In this same year there was expended on maintenance $9,972.74. If
to this could have been added the amount of difference in rates above noted,
making a total $13,378.28, or an increase of 32% each year, a very marked
improvement in condition of the system would soon be attained, but the
remarkable rates set by the Board of Investigation are impossible to Carry on
with. When one examines the irrigation rates and tolls that obtain on other
irrigation systems in the valley, it is difficult to understand the basis on
which rates could have been derived. Even where the systems are chiefly of
gravity ditch or flume construction, the prevailing rates are $12 per acre per
year or over, and even then some have difficulty in balancing accounts for
the-year, while on some such as where owned—by a Municipality as at Pen-
ticton or Summerland, additional revenue has to be secured from general
taxation. There are few systems that are directly comparable, since there
are only two of any size that are practically all pipe, that is Okanagan Centre
and Keleden, but I understand that at the latter, rates and tolls amount to
$14 per acre per yard regardless of demand.
There is also observed in Auditor's Report above mentioned that,
while the rates set should produce $12,843.63, the revenue actually received
for current year was $10,073.29. While a considerable proportion of these
arrears are collected in subsequent years, it makes the financing of operations
much more difficult and uncertain, and the question of non-delivery of water
until arrears are paid will need to be seriously considered, as has been adopted on some other Systems, among them being the one at Oliver.
Even if the full rate of $6.00 per acre foot per year were realized, it
is doubtful whether there would be funds on hand to meet serious emergencies that may arise.
F. H. LATIMER,
M.E.I.C,
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