Evening star. [volume] (Washington, D.C.) 1854-1972, 1893-07-12
7 H E AQUE DUcT
CONTINUED from Fin Page

the engineers Of the Boston water works, for
celebrating the capacity Of spiiiwAys or waste
channels required for carrying on surplus
waters in the highest freshets Is 70 provide FOR
a quantity of water that would be equivalent
to six inches in depth in twenty-four hours
from the entire watershed.
81 have concluded that II our drainage works
are planned so as to provide for the amount o.
water that. according to the Burkli- Ziegler
formula will be discharged in the heaviest rain
falls these works will have abundant capacity.
THE DAMS ACROSS EAST CREEK.
1t is proposed to construct dams across East
and Mill creeks and Little Falls branch; an
open and paved channel from East creek
around the reservoir to point on Mill creek.
around to the mouth Of a short tunnel that will
carry into Little Falls branch above its dam
the combined waters Of East creek and Mill
creek, as well as the water that now falls di-
rectly into the reservoir from the land contigu-
Gus to the reservoir, between Mill creek and
the lower mouth of this tunnel.
special provision is to be made for divert
ing from the reservoir. BY means of small paved
bitches. the water discharged from all that part
of the little peninsula lying between the lower
end of the reservoir and Little Falls branch;
that il. outside the portion OF this peninsula
that must be purchased or condemned. The
foregoing works, Of which will submit detailed
plans and estimates az soon as the necessary
drainage water that is to be disposed Of except
the water of Little Falls branch, into the
branch.
THE RECEIVING SHAFT OR WELL AND THE OUT
LET TUNNEL
Following are the plans and estimates Of the
cost of the shaft or well in the valley Of Little
Falls branch that is to receive all the drainage
of the watershed, and also plans and estimates
Of cost Of the outlet tunnel:
The we'll is to be OF the right bank of Little
Falls branch above its dam at the point marked
X (see plat NJ where there is firm ground, IN
derlaid by rock. 1t is to be ten feet in dame
ter when lined and its coping is to be at or
about the elevation Of 143 feet above datum.
CThe top Of the dam is to be 157 feet above
datum and the normal height Of water in the
reservoir is l46.5 feet above datum The
depth ct the we'll is to be about Sc feet. 1t
is to be lined with brick, backed
by concrete. From above the water cushion
that propose to provide at the bottom of the
well there will be run under Dalecarlia Hill and
below tunnel No. 4 Of the Washington aaue-
duct tunnel, whose portal on the southerly
side OF the hill will be near the outer end of
the tunnel leading from waste weir No. 2. which
Is in aqueduct tunnel No. 4. From the portal,
which will be Mt lower level than the mouth of
the tunnel leading from waste weir No. 2, an
open channel will conduct the drainage water
to the stream-the lower portion Of Little Falls
branch-that will carryit down to the Potomac
Through the drainage outlet tunnel will be
laid brick circular conduit, the vitrified brick
invert Of which will be laid on concrete. The
space between the arch and tho top and
sides of the tunnel will be packed in solidly
with rubbe stone laid in mortar.
The conduit will be seven feet in diameter
and have a grade Of .0o3l, or 81 feet in 100
feet. Two reasons have governed me in fixing
this grade
l. 1t will pass the drainage tunnel as far
under aqueduct tunnel No. A as practicable.