The record-union., 1897-08-15
DREDGING QUESTION SOLVED
ENGINEER NURSES SoUNDINGS
ON NEWTOWN SHOALS.
The Drawings Completed, Showing
That Nothing but Soft Mate
rial Composes Them.

y
borings to determine the nature Of the
Newtown shoals. been busily employed
in making a draft Of the cross-secuonaI
borings made by them.
These drawing are now finished, and
are A complete occular demonstration
of the condition of the river at the
noted Newtown shoal and of the COM
position of the material composing the
shoaI itself.
According to the cross-sectional
drawings prepared by the engineers,
three strata of material have been tap
ped in the river bed. The top stratum
is composed of fine sand intermixed
with silt, and is evidently the quota
sent down from the hydraulic mines,
and has been deposited since Mar
shall made California famous by dis
covering gold at Coloma.
The second stratum is composed of
sand similar in quality to that COM
posing the upper strata, but carrying
none of the silt from the mines. 1t
was evidently deposited before the
monitors sent down the slickens and
clogged the stream.
The third stratum is the natural bot
tom or bedrock of the river, and is
composed of yellow clay. 1t, however,
is situated only along the right bank
of the river, and is an average depth
below low tide, of twenty feet, so that
vessels of twenty-five feet draft may
pass easily, provided the sand be
dredged out, while further out in the
channel, though some of the wells were
sunk to a depth of thirty-seven feet,
the clay, or natural bottom, was not
reached. Even the clay, the engineers
believe can be easily dredged, so that
there is no impediment which will in
terfere with dredging.
Five sets of cross sectional bOrings
were made from a base line on the
right bank of the river, and extending
on an average 1000 feet into the
stream, the idea being to confine the
water TO a channel 1,000 or l POO feet
in width.
The five lines of borings practically
cover the entire shoal, so that the en-
gineers are personally acquainted with
every portion Of it.
Cross section e. is situated at the
upper Newtown warehouse. and ex-
tends 9S6 feet from the base line on
the west bank of the river. Six wells
We're bored on the line, the shaIlowest
being twenty-five and the deepest thir-
ty-seven feet.
Cross-section "a" is 500 feet below
the bOrings made on cross section e,
and extends /, ,123 feet into the stream.
Eight wells We're sunk on this line, and
515 feet from the base line, clay bot
tom was struck at depth of Is feet.
Cross-sectiOn "B'' is 600 feet further
down the stream, and here were bored
eleven wells. The borings extend LOO
the base line clay was struck at
depth Of eighteen and a half feet.
CrOss-sectiOn "C' contains nine wells,
and is $50 feet still further down the
river than cross-section "B." It ex-
tends 1150 feet into the stream and
the boring range from twenty-five to
thirty-six feet in depth.
Cross-section ID" is 450 feet fur
ther down the stream, and extends out
9S6 feet from the base line. It is op-
posite the northern point of Wood Is
land, and is practically the end of the
shoal
Several years ago a small levee was
built on the west side of the river along
a portion of the shoal. the material
being dredged from the river. The bor-
ings made by the engineers show that
since the material has been dredged
out the securing power of the water
has increased so much that the excava-
tion made by the dredger is to-day ten
times as great as when the levee was
built The depth in the dredged chan
mel averages twenty feet at low tide,
while on all other parts Of the shOal
1t will average considerably less than
eight feet
When asked respecting the report
which the engineers will make to the
Commissioner and to the Auditing
Board of Public Works, Engineer
Nurse said:
1T is impossible at this time to
even outline except in a general way.
the recommendations of the report to
be presented by the engineers to the
Commissioner of Public Works to the
Auditing Board, but an examination of
the cross-sections as mapped by AS
sistant Engineer Randle viii give a
very comprehensive idea Of the general
plan Of the engineers, in regard to the
removal of the Newtown Shoals. and
also gives an Occular demonstration in
verifcation of the opinion held by En-
gineers Price and myself, that the
shoals are removable.
From the mouth of Cache Slough to
the town of Rio Vista and along the
borders Of Reclamation District No
$50, an embankment was thrown UP by
a dredger a little over a year ago,
which serves as a levee for the district,
and a country road to connect Rio
Vista with the river islands The eX
cavatiCn was not great, being limited
by the capacity of the machine for
such work. and the necessity for but
small embankment, but by this means
alone the current was greatly acceler-
ated and a securing action was begun
which has resulted in an excavation
through one side of the shoal that is
along the bank of the river and
equal to many times the volume of the
earth removed by the dredger and ex-
tending to the natural bed of the
river.
That this result was accomplished
by the means suggested is evident from
a comparison of the soundings taken
during the progress OF the work just
completed with those taken in previous
years as far back as 1873.
1T is thus demonstrated almost be-
yond dispute that a good dredger. aid
ed by well constructed jetties to con-
centrate the force of the water. would
remove the obstructing shoal and in
crease the carrying capacity Of the
river to such an extent as to improve
navigation. and solve in a. great meas
ure. the problem Of controlling the food
waters of the lower Sacramento"
NEW CARS.
Twenty-Five to be Constructed and