Evening star. [volume] (Washington, D.C.) 1854-1972, 1904-07-02

is merely to keep the water in the peas at
a certain height, and the quantity passing
through the filters is increased or decreased
by the opening closing OF the outlets.
Each five chambers will have one governor
house where these valves are manipulated.
After a filter has been In use for some
time 1t is necessary to give freer vent 10
the effiuent water in order to. overcome the
resistance produced by the accommodations
in the sand.
In the probable event that the demand
will ultima tely outgrow even this supply as
the city grows in size and population. there
is land owned by the government adjoining
the present works upon which large num-
Der OF additional beds may be constructed
, to meet the condition.
Source Of Supply.
The water to be filtered will be taken
from the Howard University reservoir and
forced by the pumps of the new pumping
station into the filters. 1t will percolate
slowly downward through the sand being
drained off by the terra Gotta pipes into
the mains leading to the clear water reser-
voir, which holds about one-third of the
daily capacity of the filters. From the
clear water reservoir the filtered water will
be forced through the city mains by the
Trumbull street pumping station
1t is said that when the water is first
turned in on the fresh sand there will be
but slight change perceptible in it's con-
dition for several hours This is because
it is necessary for the intervals between
the grains of sand to be filled to a certain
extent by the particles suspended in the
water before all the impurities are re-
moved Gradually, as the process contin-
ues, the sand becomes clOgged and the pas
Sa ge of the water impeded perhaps finally
stopping 1t. The filter then has to be clean
ed by the removal of the surface sand and
the deposit. 1t is only necessary to re-
move about half An inch of the upper sur
face of the sand in the cleaning, for all i'm
purties are deposited and held at the sur
face. The sand that is removed is not lost,
but after a process of washing by means of
special devices which will be supplied 1t
is stored in the courts before each bed, and
! when required returned to the chambers as
clean and efficient as ever This cleaning
process will have to be done more or less
frequently. according to the degree of tur-
bdity of the water filtered, but probably
will be at intervals of about one month.
In the accomplishment of this work 1t
has been necessary for the contractors
| to install a complete system of railways
! with large amount of rolling stock, an
/ electric plant. saw mill, concrete mixers
and conveyors and trestlework upon which
| to unload cars of broken stone, sand and
! cement as they come in from the Balti-
more and Ohio tracks over a branch road
| laid to the works specially for this traffic.
| Several enormous towers have been erected
between which stretch heavy cables ira
verSing the areas of active work. On
| these cables great buckets of concrete are
| hurried to where they are needed. These
| loaded buckets are transported between
| the mixers and the towers over the rail-
way. several engines being kept coitinu-
| ously busy shifting the trainloads of loaded
| or empty buckets.
| The firm having this work in hand is the
| Sand Filtration Corporation of America
| which was evolved from the firm of Dean
! & Shipley January I. That company took
| over the work from May & Jekyl to whom
| the task sublet by Bradley Clay &
| Co, who obtained the contract from the
| government March 81. 1903. The time for
| the completion of the filtration plant was
| limited to two years from the date Of con-
| tract.
The construction of the supplementary
| pumping station is under the direct super
vision of government engineers