The Jersey City news. (Jersey City [N.J.]) 1889-1906, 1892-05-23

IVA
In their partial report the engineers
nj ade the following criticisms as t. the
reservoir capacities and their cspability
of supply
l.. The drainage area above Oak Ridge
Ia CAPABLE of furnishing more water than
can be stored ia the reservoir.
2 The Clinton reservoir has a small
watershed as compared with Its ca opacity.
8. The reservoir at the Macopiu intake
has no practical value rs II storage reSer-
voir. consequently the lower part of the
watershed eau be utilized only to the eX
tent Of its natural daily drainage, ana Il
very large proportion of the freshets will
BIZ wasted over the spillway of the dam.
4 We further believe that the capacity
OF the present systemin a Tin of drought
would not exceed thirty-five million gal
Ions for each and every day in the Year.
TEsT OF THE REPORT.
1t is interesting to test these criticisms
by other authoritative standards ali d
published records of water supplies. No
gauging of the flow of this area for a
term Of years has been made. 1t can only
be estimated fairly by com parison with
the record of the adjacent. and closely
similar drainage area OF Lake Hopatcong.
According to thai record. as published in
the State Geological Report Of New Jer-
sey. and by Croes and Howell. Report on
Additional Water Supply. Newark, 1879,
the average annual rainfall in twenty
fonr years.
j. 7. Tanning, Treatise On Hydraulic
nd Water Supply. Engineering, page so,
gives the following rule:-"When it is de-
sired to utilize the greatest possible uor-
ton of the flow. the storage should equal
20 or 25 per cent. OF the mean nnual
rainfall" Twenty per cent of 1855
inches is 8.51 inches. Rainfall 8 Isl
inches on 27.5 square miles, reckoning
II, 424. 600 gallons per inch. per square
mile. is 4.077, 65l 600 gallons.
A RIDGE DRAINAGE EXCESSIVE.
The storage capacity Of the Oak Ridge
drainage area, as mt present provided, is
only 2, $50, 900, 932, 900 gallons, plainly u de-
ticiency OF three-eights of the proper
amount, according 10 the lowest per-
centage of storage required by Fanning's
tion of the flow" 1t will not be ques-
toned that the demand OF Newark re-
quires such utilization. since the mean
annual flow of the Pequannock area, even
If 1t exceeded the ratio of the Hopatcong,
Sudbury River, Cochituate. Mystic and
CroJon areas. would barely meet the
maximum requirements OF the contract.
If the Oak Ridge area has too small a
storage capacity by Dearly o%ne-half, it is
mauifestly desirable that the o her Two
reservoirs should remedy the deficiency.
1t remains to be seen at what rate the
Clinton reservoir will probably fill, and
how far it will probably become service
able to remedy the deficiency in Oak
Ridge storage
CLINTON RESERVOIR INADEQUATE.
With IL mean annual rainfall of 42.55
inches. forty per cent. OF this depth is a
safe estimate of the amount annually col
lectable. This Is according to the general
practice. Taking into account. however,
the pare rock surfaces, ana many precipi-
tous slopes of the little Clinton drainage
area, suppos fifty per cent. of ths rain
fall on the area is collectable. This would
be 81 81 inches, or 8,706. 0S4. 800 gallons u
year. The storage capacity provided Is
3. 534, $780, 600 gallons, or substantially the
same as the amount annually coilectable
if the above high rate be attainable.
But the relation of this storage capacity
to the utilization of the greatest possible
portion of the mean annual flow Is mos
important. Using again 20 per cent. of
1855 inches as the proper standard for
storage capacity for Such utilization. s 81
inches on lnis area would be 1.482, $50, 400
gallons. The amount of storage provided
being 1854. $50. 900 gallons, is, therefore,
two and Il nnlf times that required for the
drainage area in order to utiiize the flow.
NO SUFFICIENT sToRAGE RESERVE.
This great storage capacity YOU be a
good Offset to the Oak Ridge capacity,
were 1t not for two reasons:-
First, 1t depends on II very small drain-
age area from which it will not probably
be filled in less than a favorable year, and
from which in time of drought 1t will not
probably be filled in one year.
Second it must stand a constant and
heavy draft whenever the contract de-
mand of SO, 0Oo, 900 gallons a day is APP
proached.
The e~xigencies of the supply under the
contract will not permit the Clinton water
to be held for reserve storage. The Clinton
area, being about one-sixth of the whole
Pequannock area. should be able to stand u