Evening star. [volume] (Washington, D.C.) 1854-1972, 1882-02-18
POTOMAC RIVER IMPROVEMENT.
OFFICIAL REPORT OF COL. ALERT.
Account Of the Survey OF the Harbor-
Plans and Estimates for the
Work Of Filling the Flats, &c.

provement OF the harbors OF Washington and
Georgetown, and the survey made last summer
and fall by him:
~ have the honor to submit herewith brief
summary OF the results obtained by this survery
between htthe Aqueduct Bridge and Giesboro' Point,
together with plan and estimate for the improve
ent Of the navigation and the raising of the fats
and for establishing the harbor lines Of Washing
ton city. These results and estimates for the
Improvement eff Washington harbor are trans
mftted at the present time in order that they may
be laid before Congress in time for early cSnsid-
Grafton. The remainder OF the report, relating to
the Anacostia river and to that part Of the
Potomac river between outlet lecS and inclined
plane 0 the Chesapeake anE Ohio canal, together
With additional data in regard to the harbols Of
washington and GeOrgetOwn) will be transmitted
as soon as 1t is completed.
. THE SURVEY
was commenced at the inclined plane OF the
Chesapeake and Ohio canal above Georgetown on
the Potomac river, and at the Anacostia bridge on
the Anacostia river, and terminated at Giesboro
Point where the two rivers unite. The shore lines,
bridges, wharves, &c, were located, and thirty
seven cross sections taken. On these cross Sec
IONS soundingS were taken every fifty feet, the
distances being measured by means OF small
wire rope. Velocity observations .Or ebb and food
tide were taken at each cross section. Tidal OBJ
servatiens were taken during the progress OF the
survey at the outlet lock, Aqueduct bridge. G
street wharf. the Long bridge, Arsenal point, nd
shows the locations at which these cross sections
We're taken, the widths, at low water, the maxi
mum depth at low water, and the sectional
areas at low tide, high tide, and during
the the freshets OF 1881 and 1877. In
explanation OF this statement 1t should be stated
that below Esbys Point the width OF the river in
creases from ga feet to about 900 feet losing its
distinctive tiuyial character and expanding into
the wide tidal area known as the hlrbors OF Wash
tngton and Georg gstown. The sectional AREA OF
high-tile ana OF froshet below Easbys Point do not
therefore, represent the area Of discharge which
6 tod in i'm,
the freshet water simply flowed over this wide ex-
Tent OF hats and marshes at a greatly reduced We
10 tos, ty: me altitude OF the freshet OF February
1881 was maintained, as indicated in the table, by
the lce-Torse at and below Long Bridge. The
croS5-Sst ton OF the Washington and the George
town channels into which the river divides, and OF
the HatS between them, are separately indicated
i'll the table,
INTERESTING RESULTS.
The report then des RIDES tie method OF taking
the velocity observations and continues as fol-
lows "rhe plat, of tlool and ebb show some inter
estng Sults as to thc effects OF the tidal currents
upon the fluvill discharge OF the river. From the
Little Falls to point near the Potomac Boat Club
house in Georgetown there are down stream cur
rents and fluvia1 discharge during the entire
PERIOD o! fOOi tdc, so I'll It the only effect OF the
ilooi tidal current above Georgetown is TO rass the
SURFACE OF the water without c3u ing any food
discharge. PlatS OF the flood and ebb currents
accompany this report
IN THE ARRANGEMENT OF THE BULKHEaD LINES
OF nitng shown on the map it has not been practi-
cable, on account OF economical considerations to
make them exactly concentric with the lines OF
mid-volume. The curvature Or these lines Will,
however, be made more conformaele by the altera-
ton OF the position OF the crossectlon OF the pres
ent channel"
SECTIONAL AREAS.
In making the calculations for the Improvement
OF the river, it was necessary to determine the
low water sectional area, which should be
o6 0c tam III
area of the river, between toe Aqueduct bridge
and EaSty's Point, was found to be 9316 squl
feet, and Tor the Georgetown CHI 3nnel. between
Eisby's and the Long bridge. aO,679 square feet
The sectional area at the Long bri ge was believed
To present the "On tiOnS necessary for deterinin-
Ing the area which should be assumed as the
standard in the calculations for the improvement.
In these calculations the heights OF ireshets
assumed are those OF the freshet
Of fTesnd5 l5 Whfh =, ,sy, vas actually higher
the Latter above the Long bridge being due to the
Ice gorges at that point, as already stated. The
cross sections taken parallel with and SO eet above
the Long bridge showed the sectional area OF the
Georgetown channel to be 81 ,o5l squire feet (be-
tween the lines of the abutlnentsl; that OF the
washington channel to be 1869 square feet and OF
the hats between ,S26 SQUARE feet. The sectional
area OF the Washington and Georgetown
ee 9ssfhsr From at s shs pont pn is to i
arsenal wharf the average section of the
TWO channels together is about 2i 500 square feet
not inciuting the mats between them AS the
GeofsetoWn channel Will, upon the completion OF
the Improvement, be called upon to discharge the
entire body OF the freshet water. its low-water
section should be equal to the combined section of
the two channels; and in view OF all the facts
ascertained by the survey, the standard low-water
section has been assumed at 25.0 square feet.
PROVISION FOR THE FREsHET DISCHARGE
The sectional area Of the freshet of 1877 has been
assumed as the STANDARD in providing for the
freshet discharge. sectional of 4S 600 square
feet, with rise OF 10 feet has been provided for at
TIE Long briige In order to discharge this
sary to remove the causeway which forms a part
OF the abutment OF the southern end OF the bridge
for distance Of about 400 feet, replacing
liar to those now in use.) the causeway
to be removed to a depth Of three feet at
meath it. The sectional areas above and below the
bridge viii be sufficient for the discharge OF the
water fresheCs. a. The low water sectional area
assumed as d standard is % 0O0 square feet. (2)
Ihe high tide sectional area assumed as standard
IS 32S15 square feet Ci) The freshet area assumed
as standard is eco square feet
THE LIMlTs OF THE FLATS TO De RECLAIMED,
as contemplated in the act, by of the dredged
material, the port warden lines for the Washing
ton channel or inner harbOr, as well as the outer
port warden line, beyond which neither wiiarves
nor landing slips viii extend, are Indicated on the
acco:np nying tracing On the Georgetown chan
mel, and the haTSor line c0InIncnceS at EaSby's
wharf, following curved line To the Southerly end
of the cansewsy Of the Long bridge, thence on
curve ne.,ry paralle. with the river channel to a
point on the fl It's below the Arsenal wharf at the
intersection o. tue two channels
FOR THE WASHINGTON CHANNEL
the inner line follows nearly the limits of existing
wharves, and the outer line OF the Washington
harbor is 800 feet from the inner line.
TIE INNER LINE,
beyond which 1t is recommended that no wharves
be allowed to extend, is as folows:-Connencing
at point 25 feet outsid. the northwest corner OF
Riggs wharf. running thence in straight line to
point Is feet outside; thence southwest corner Of
the lower wharf of the Great Fails Ice Co.; thence
in a straight lne to a point q feet outside the
southwest corner OF Evans stoneMhart; thence in
straight line To point q feet Outside the north
west corner Of Gse thill wharf below the Alexah-
drla Ferry Company's Slip: thence in a
straight Tine to the southwest corner Of the
wharf OF the Inland and Seaboard Company, and
continuing 10 paint 1S0 feet above the first angle
In the arsenal wa1l and ed feet west OF eatd wall:
thence to point $50 feet outside OF the arsenal
wall at the site OF the old pentsentiary wharf:
thence to point 10 feet west OF ftenorthweSt cor
nor OF the existing arsenal wharf. The Washing
ton channel, above the Long Bridge is left open as
far as 17th street The greatest dcith of the Gee
tonai area OF discharge is assumed MS equal to the
greatest depth OF the proposed channel the as
sumption being based on the observations OF voc-
iueS OF ebb and 1ood tide The Stgt OF the chan
mel south of the reclaimed being partly an es-
tuary OF chesapeake bay, may have low Water
sectional area greater than the low water section
Q. the river at that point without any alteration OF
the present low water surface OF the river.