Evening star. [volume] (Washington, D.C.) 1854-1972, 1899-01-17

of these flats as the cause of malaral dls-
ease in that institution.
Reclamation Necessary.
THE insantary conditions whlch exist oii
tho Anacostia river are substantially the
same as those that existed on the Potomac
in front of the city of Washington prior
to the inception of the Potomac river itii
,nrovepent, The reclamation of the Polo-
mac flats although not as yet entlrelS eout-
pleted, has very largely corrected the m
sanitary conditions along that front, thouSh
sewers still discharge into the river Inc
success of the Potomac work gives every
encoura cement to undertaking similar WORK
on the Anacostia, for the double purpose Oh
channel and sanitary Improvement. Even
were a project carried out for the compre-
hensive and satisfactory disposal OF sew
age by other methods than discharge OF lhe
same into the Anacostia, or INTO the foto-
mac Improvement of the river would DE
deSira hle as there would Stlll be depoSllS
of sediment during heavy freshets in the
Potomac not to speak of existing obstruc-
tons to navigation in the shape OF shoals
and tortuouS Channels.
The mean range of tide at the navy yard
is-according to the United States coast
and geodetic survey observauons-29 feet'
practically feet.
In any plan for Improvement OF the chan-
mel of the Anacostia dependence for main
tenance Of increased depth should rest
mainly upon the tidal flow. Obstacles to a
free tidal flow should be removed and the
TIDAL prism diminished DIS lillic pOSSA'iS
consistent with the accomplishment of
other essential features of the improve
ment.
las to the least depth of channel to be
secured:
THE present plan for Improvement of the
Potomac river at Washington provides for
a navigable depth at mean low tide of 20
feet, which is about the ruling low-water
depth on the shoals between Washington
and the mouth of the Potomac. An increase
of the ruling navigable depth to "a feet,
or more, IL ordered by Congress, would
render necessary the same ruling depth OF
channel for the Anacostia river up to the
navy yard at least. Taking the present
plan, however, for depth of 20 feet in the
Potomac as a basis, the necessary ruling
depths for navigation of the Anacostia con-
sidered in this report are 20 feet at low
water from the mouth of the river to the
navy yard, for width of 400 feet; thence
to Benning bridge, depth of 16 feet for
widths of 200. to 500 feet. Outside of the
bounding lines of the widths named the
dredged depths may be gradually reduced
so far as navigation is concerned. AT the
bulkhead lines the dredged depths should
not be more than feet. In some portions
of the river, however, well removed from
the bulkhead lines. dredging to considerable
depth will be required in order to obtain
material for fill on the flats.
Cost of Improvement.
1.-The cost of improvement of the Ana
costa river and reclamation of it's flats
will depend mainly upon the cost Of dredg
ing the channel and deposit of dredged and
other material upon the flats The total
cost of Improvement will also depend upon
the grade elevation to which the filling
on the fats is to be carried. The low grade
fill Ito an average elevation of seven feet
above low tide, with a minimum of six
feeO would be protected against overflow
from freshets of the Potomac by an en-
bankment or levee along and near the
bulkhead line, raised to a height of four
teen feet above low tide, with provision for
drainage of the inclosed area. This method
of reclamation would not be so complete
so desirable, probably from a sanitary
point of view would high grade fill
carried over the entire area to a height of
fourteen feet above low tide, or to ele-
walton of three feet above the highest fresh
ct line.
Two estimates are here presented; one
for the low-grade fill and the other for
the high grade-the sea wall proposed TO be
of rubble masonry resting on a riprap foun-
dation similar to the sea wall built for the
Potomac river improvement at Washington.
Some settling of this wall, founded on soft
mud, should be expected, and allowance
for 1t should be made in placing the faeln-
dalton. For the section above Benning
bridge a slope wall, or paved slope, has been
substituted in the estimate for the sea wall,
it being less expensive.
ION the portion of river between Benning
bridge and the District line the two require
ments of providing tidal space and reclama-
ton of the flats can be met either by widen
ing the existing channel or by dredging
tidal reservoirs, the dredged material in
either case to be deposited on the flats.
There seems to be no probability of any
trade in this part of the river calling for
an improved navigation channel
Estimate by Sections.
'The two projects for Improvement from
the District line to the mouth, with esti-
mate of cost by sections. are as follows:
Il. Dredging channel and depositing ma
terial to an average elevation of seven feet
above low tide, including construction of