St. Tammany farmer. [volume] (Covington, La.) 1874-current, 1901-03-02
COLOSSUS OF ENGINEERING.
Four thousand Acres Stripped to the
Depth of q Foot to Prevent
Microbe Infection.

The magnitude of the work of
building the big Wachusett reservoir
can be appreciated when it is under
stood that the plans of the board call
for the stripping of the entire area
to be occupied by the reservoir to an
average depth of about one foot.
This means the removal of one foot
of soil from an area containing 4,195
acres of land, not a small task in
itself. The cost of this item alone
will exceed s3,oOO.OOo says H. H. Lew
is, in Ainslee's.
| This stripping of the soil is a proof
of the thoroughness of the boards
work. The three members, Henry H.
Sprague, Wilmot II. Evans and Henry
p. Walcot, showed no hesitation in de-
Gliding to incur the expense when it
became a question of absolutely pure
water or of water partially contain
mated. In the brush, peat, mud and
minor organic matter. which accumu-
late at the bottom and along the sides
of reservoirs there is danger of germ
and microbe infections bare danger,
but enough to warrant the cheerful
paying out of millions to avoid pos
sible pollution.
The main dam. which is the key to
the whole stupendous scheme. is To-
Gated across a narrow gorge about
1900 feet above the dam of the Lam
caster mills. at Clinton. The general
form of the cross section is the same
as that adopted for the new Croton
dam in New York. 1t is similar in
many respects to the Furens dam,
upon the ,Furens river. in France,
built in 1866. mad to the Tansa dam of
the Bombay waterworks. construct
ed in 1891. The dam win rise ten
feet above the level of the full reser-
voir. At the water level it has
thickness of 10 feet, and 145 feet be-
low the water line the thickness in
creases to 1917 feet.
1t is composed entirely Of masonry.
Its total length is 1880 feet; but only
$50 feet have a depth from high water
to the rock exceeding 40 feet. and but
one-fifth exceeds 100 feet in depth.
The maximum depth from high water
to the rock at the down stream edge
of the dam is 15S feet.
Advantage has been taken of the
favorable topography at the norther-
ly end of the dam to provide very
long overflow. and a waste channel
for wasting the water during floods
without permitting it to flow over or
near the high part of the dam. The
overfall has length of $50 feet. and
will discharge quantity of water
eq,sl to eight inches in depth over
the whole water shed in "a hours.
The greater part of the overfall is to
have a masonry crest at the level of
the full reservoir, but for length of
120 feet it is proposed to retain the
water at the full height by means Of
stop planks or movable gates.
Next in Importance to the building
of the great reservoir must be placed
the construction of the Wachusett
aqueduct. This work begun early in
1896 and completed in 1898. embraces
(D tunnel two miles long through
rocks so compact asnot torequirea a lin |
ing for half its length: (2) masonry
aqueduct, seven miles long. with a
bridge of seven spans and 360 feet in
length across the Assabet river, and |
(3) an open channel three miles long. |
following the course of brook into |
Sudbury reservoir.
The masonry aqueduct, which is II
feet four inches wide and ten feet Ave
inches high, has maximum capacity |
of 3OO.OOO,0Oo gallons daily. 1t ter
at a point on the Sudbury
water shed in the town of Northboro.
Its waters then run for three miles
an open channel. which is
90 feet wide at the bottom, to Sud-
bury reservoir, from which a second
aqueduct issues. branching at Weston
into two great pipe lines. one taking
a northeasterly course to Arlington,
the other running southeast to
Chestnut Hill reservoir.
The cost of the tunnel was $342,-
D05.sO: of the masonry conduit, in
cluding terminal chambers, $685.
l07 81; of the Assabet bridge, $685.
a39.46; of the open channel, $l7O.-
D5o.32. Including preliminary and
work and other items,
The total cost Of the aqueduct was
S1.763. .5O5.1s,