The record-union., 1893-09-19

and too steep.
Furthermore, the matter of the waste
ways is ambiguous and the design of the
Waste-Weir imperfect.
The perishable character of wood and
brush. largely employed in the construc-
ton of the old barrier, does not insure
permanency of the structure and it is an
| Objectionable feature to use the old dam
| so constructed as q foundation for the
new.
Stability under these conditions is not
assured. Very respectfully,
STRIEDINGER & Won GELDERN.
Civil Engineers.
THE OMEGA COMPANY's PETITION.
SAN Francisco, Sept. 1, 1893.
r. Z. DeUtin, Attorney-dt-LGw Anti-
Debris ASS0ciGtf0n-DEARS SIE: We have
made certain examinations of the petition
of n. Z. Tully IL Co. for permission to
mine by the hydraulic process certain
mining ground known as the Omega
Water and Mining Company's claims il
Nevada County, Cal.
The petitioners propose to operate upon
a ground 500 feet long, 500 feet wide and
so feet average depth.
The debris is to be stored in Scotch
mans Creek, tributary of the South
| Yuba River, and for that purpose they
have projected dam across the ravine,
about 600 feet above the mouth OF the
creek, to create storage basin.
This dam is TO be constructed of stone,
gravel, earth and brush, and is to have
such height that no water is ever to run
over it, but is TO be turned over ledge of
solid rock. There weir is to have suffi-
cient capacity to allow free passage of all
the water that may ever come down
Scotchman's Creek.
The dam viii be about 440 feet long on
top and l35 feet at the bottom. It's base
h \
feet.
The area is calculated to be 1888 acres
at the water level, with capacity of
about ,000, 900 cubic yards of water, and
nearly twice that for holding back the
detritus.
The fall of Scotchman's Creek is 3.3S
feet in 100.
The petitioners do not state anywhere
the hight to which they propose to raise
the dam, unless we consider a certain
diagram submitted to the United States
Debris Commission as the required data
for that purpose. a cOlored section there
upon would indicate that it is proposed
to build a dam fifty feet high, and when
this is filled to hight of about forty-tiye
feet, to set upon this dam an addition of
/ thirty feet Of similar proportions. which
shall rest in part on the top Of the first
dam, and in greater part on the debris
| pile back Of it.
With the petitioners papers is sub
mitted a croSs-section of the ravine on the
line Of the proposed dam. This shows on
the right the section of q gravel hill,
rising about one OH one, with bank of
! tailings at it's foot, and on the left is indi-
Gated a slope, marked ''Slate Rock" If
| on this croSs-sectiOn the line of the top of
the fftyfoot dam be drawn, we shall find
! that at that elevation the surface of the
slate rock has slope of 260 with the
| horizontal.
1t is difficult to see how, under these
conditions, the petitioners propose TO
| construct the spillway or weir, which is
an essential feature of the project, so as to
turn the waters over the ledge of solid
rock, and to prevent the overtopping of
| the dam, for the reason that the security
Of the dam depends upon the proper
planning. dimensioning and construction
of this spillway.
1t will not do to make the simple state
ment that weir forms part of the pro-
iect, without going into some detail as to
the manner Of its construction and con-
nection with the dam proper. 1t is the
most vital point to be considered in the
safety of the structure and in the creation
of an effectual restraining barrier.
Since Il large amount of brush and
wood enters into the proposed structure,
there are likewise certain objections iusti-
the wellknown perishable nature Of such
material, the permanency of the dam is
not assured.
Section Is of the Caminetti Act calls for
specifications in detail of all the methods
under which the operations shall proceed,
and this implies explicitly that all pro-
posed constructions shall be clearly set
| forth.
There is another deficiency in the topo-
graphical data submitted which makes it
an impossibility to check the quantities
furnished by the petitioners. There are
mo means at hand TO calculate the capacity
of the storage basin and to compare it
with the amount of debris to be stored.
We find among the diagrams Of the pc
titioners only one cross section for the
whole length of the impounding basin;
neither is there given q longitudinal sec
tion of the creek or ravine to be used for
storing; and with such meagre data it is
apparently impossible to deal with this
subject, except in the most general way.
Another factor in the case is not suffi-
ciently clear for the purpose of treating
the subject intelligently, and that is the
character of the material to be washed.
Calling it ancient river wash does not
clearly imply its nature, and for that
reason it is desirable that better informa-
ton in this particular be given.
The petition is objected to on the
! GROUNDS tnat the data SuDlnlJted are not
specific enough to furnish all the required
Information regarding the proposed
method of storing.
We claim that before the petition can
be acted upon inteligently, and before
the application can be considered, better
facilities should be afforded for examin-
ing the technical details to which we have
referred.
Technical drawings and specifications
should be submitted showing the con-
struction OF the proposed spill way, and
that Of the dam proper; the Typographical
features should be much clearer, and
| fortified by collection of more specific
data; more satisfactory description Of
the gravel to be washed should be given.
The project is not clear, and we. claim
that in its present shape it should be re-
turned to the petitioners for more specific
data. Very respectfully,
STRIEDINGER IL VON GELDERN,
Civil Engineers.
1t was decided to wait another month
before coming to definite conclusions on
this subject. The committee then ad-
journed TO meet at the same place on the