The Worthington advance., 1901-02-08
COLOSSUS OF ENGINEERING.
-Four thousand Acres STRIPPED to thu
Depth Of . 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 small task in
itself. The cost of this item alone
will exceed $3,ooo,o 900, 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. r. Evans and Henry
P. Wa1cot, showed no hesitation in de-
Gliding to incur the expense when it
became 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
5000 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. It 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 will rise ten
feet above the level of the full reser-
voir. At the water level it has a
thickness of 10 feet, and p45 feet be-
low the water line the thickness in
creases to 1872 feet.
It is composed entirely Of masonry.
It's total length is 1880 feet; but only
$50 feet have depth from high water
to the rock exceeding 40 feet, and but
one-fifth exceeds 12o feet in depth.
The maximum depth from high water
to the rock at the down stream edge
of the dam is 1853 feet.
Advantage has been taken of the
favorable topography at the norther-
" end of the dam to provide a 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
equal 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 a 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
the construction of the Wachusett
aqueduct. This work begun early in
1896 and completed in 1898, embraces
Q) tunnel two miles long through
rocks so compact asnot to require q lin
ing for half it's length; (2) q masonry
aqueduct, seven miles long, with q
bridge of seven spans and 36O 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 five
inches high, has maximum capacity
of 300, 100000 gallons daily. It ter:
inmates at a point on the Sudbury
water shed in the town of Northboro
It's waters then run for three mile.
through an open channel, which 4is
20 feet wide at the bottom, to Sud.
bury reservoir, from which q second
aqueduct issues, branching at Weston
into two gl eat pipe lines, one taking
ainortheasterly course to Arlington
the other running southeast te
Chestnut Hill reservoir.
The cost Of the tunnel was $342,.
0o5.s0; Of the masonry conduit, in.
eluding terminal chambers, 1868,
107.s1; Of the Assabet bridge, $66,
239.46; Of. the open channel, $17o,,
o5o.32. Including preliminary and
engineering work and other items.
the total cost of the aqueduct was
t1,7es. .5o5.le