Evening star. [volume] (Washington, D.C.) 1854-1972, 1910-08-01
Method of Repairing Aqueduct
Bridge Criticised.
is DECLARED INEFFECTIVE
Capt. Hannum Says Masonry of All
Old Piers Will Give Way.
THREE REMEDIES SUGGESTED
Engineer Officer, in Report, States
That New Structure Could Be
Built for $95O,ooo.

The present method Of repairing the
EAqueduct bridge across the Potomac river
kat Georgetown is at best but patchwork
Wand. Whlle tending to prolong the life of
he masonry of the piers to a certain ex-
TENT, is not effective in arresting perma-
ently the process of dissolution. Capt.
Earren T. Hannum, the engineer officer
charge of the Improvement of the Po-
pmac river. makes that statement in his
nnual report to the chief of engineers
he piers. he says, have been placed in
good condition as is possible with the
nds available for the purpose That
Ne deterioration is progressive is shown
says, by the fact that new defects
discovered at each examination which
not exist at the last previous exam
in tion.
s the occurrence of cavities in the
plerS cannot be anticipated and pro-
vIved against by the present method Of
patching. capt. Hannum expresses the
beNef that IN time the masonry in all
OF the old piers will deteriorate to such
an extent That repair by any method
ent method be abandoned in favor of a
more certain and permanent one or the
piers be entirely rebuilt
Proposes Three Remedies.
There are. he says. three possible
ways of remedying present conditions
Plan A-By replacing the present
bridge with an entirely new one, pref
erably with fewer piers and longer
spans. This plan was considered by
Congress in 1902, but was not adopted
Capt. Hannum says that while the
amount required for a new bridge
would depend on the type of bridge Sc
lected, 1t is believed that suitable
structure can be built at a cost not to
exceed $95U,00O, including removal of
present structure.
Plan BY replacing the five old piers
by new ones, as has been done already
with piers one, four and five. This plan,
capt. Hannum says, would provide per-
manent and reliable supports Of uniform
appearance for the present structure, but
would not provide tor any Improvement
in 1T. AS far as known the south abut-
ment is in safe condition. It Is be-
1ieved that the north abutment can be
made reasonably secure by thoroughly
ripra apping in front of it. That treat
ment, he says, is prohibited In the case
OF the piers on account o. the reduction
in the cross section of the river which
would result from the use OF a sufficient
amount ot riprap to protect them ef-
fectively. In his opinion, the removal Of
the five old piers, which are larger at
the base than the new ones would be,
and which are partially protected by rip
rap, which also would be removed. would
increase the cross section of the river
sufficiently to make the placing of addi-
tional riprap at the abutments permis-
sible. The estimated cost under this plan
is $3.50, GEO.
Would Make Piers Solid.
Plan C-By providing some means of
making each of the old piers as solid
a mass of masonry as possible to pre-
vent further deterioration in the exterior
surface In this plan Z. is proposed to
surround each of the old piers with a
jacket. or she'll of reinforced concrete up
to or above the water line, after thorough
ly cleaning out and groutins such open
joints of the Interior as are accessible.
The work rs to be done within a Golfer
dam, which could be used w-h compara-
lively slight alterations at each pier sue
cessively. While the exact condition of
the interior OF the piers cannot be as
certained by divers examination. Capt.
HSnnum says he believes the prir c.pal de-
fects are in the face masonry and that
If that be properly repaired and confined
against movement there will be no fur
ther deterioration. While the concrete
Jackets would Increase slightly the OBJ
struction due to the piers themselves.
Capt. Hannum says that the removal of
the riprap, which would no longer be
needed. from around them would more
than compensate for that. The estimated
cost under this plan is S15O,0O0 which
would provide also foi. any repairs found
necessary at the ab,ltmentS. Tentative
plans for cofferdam such as would be
required under this plan have been made
and sOundings and probings around all
the piers in order to determine as ac-
curately as possible existing conditions.