The Providence news. (Providence [R.I.]) 1891-1906, 1894-08-03
NATURAL METHOD.
The Joint Special Committee on FIJI
tratIon Vote to Adopt 1t.

The joint special committee has voted
unanimously in favor of the natural sys-
tenn of filtration for Providence.
The committee met this forenoon at the
call of the Mayor for a final discussion OF
the reports Of the experts. The letter OF
III. W.. Clark of Lawrence to Commissioners
Smith was presented to the COMMITTEES;
1t reads as follows:
LAwREScE, Mass, Aug. ]. 1894.
Robert r. Smith, Commissioners OF Public
Works. Providence, r. j.
sm-I herewith submit to you mi report OF
the results obtained by examination and
mechanical analyses of the samples OF
sand obtained in Providence, July
28. The samples were taken from
test pits dug In various parts of the city land
across the river from the pumping station of
the Providence Water Works and from the
bank near the Corliss engine house Of pump
ing station.
The results are extremely satisfactory and
establish the fact that there is In the imme-
date vicinity Of the pumping station an
ample supply of sand free from organic mat
ter, and OF an excellent quality and grade
TO be used for the publication OF
water by natural filtration. The sand
Is very similar to ana within the limits of eff
fective size Of the sands used in the expert
ments made by the Massachusetts, State
| Board of Health at its experiment station at
Lawrence, Mass, and Of the sand used In the
construction OF the city filter at Lawrence
Mass.
or the sands examined those from the test
| pits numbered l. 2 3. 4. 8. g.. Z, 3, 8 and 10 are
well adapted for use in a filter constructed
according to the plans shown me
by Mr.. Shedd. the city engineer. Such
sands. when perfectly underdrained. with
surface clean, and an acting head equal to the
| depth of the sand. would allow water TO pass
at rates varying from twenty-five million
gallons per acre daily with sand from test pit
No. 10 to eighty-four million gallons per acre
daily with sand from test pit No. 8. This Is
when the sand is first put in position. As II
becomes more compact from settling the
maximum rate would considerably decrease.
Sand of a uniform grade and. similar to that
obtained from test pits Nos. I'd and o could, |
believe. be obtained without much difficulty
and perhaps would be the most satisfactory
for use.
In conclusion / would say that I see no rea-
son why the city Of Providence cannot have a
filter that will. with proper management. fl
tering water at rates not greater than two or
three million gallons per acre daily. give the
city "a pure and satisfactory water supply.
Yours respectfully. II. w. CLARK.
The report referred to is an elaborate
table Of estimates and percentages rela-
tive to theisize and cleansing capacity OF
the different sands submitted and Their
ability TO withstand the action of water.
uo- l.st.r mae raoA fpnm NJ
Mason, a local expert, who performed hii
analysis and comparisons Independently
Of Mr.. Clark.
OF the Providence sand he states thai
S5.945 per cent. passes through 80 meshe:
10 the linear inch and 43.5s5 per cent
through 100 meshes to the linear inch
The sand is sharp angled and but little
worn by the action of water
OF the Lawrence sand 9S. 1876 per cent passe
thr ough 80 meshes to the linear inch, ant
81. 800 per cent through 100 meshes to TIT
linear inch. This contains considerable
mica and a great many grains rounded b,
flowing water.
After the reading of the letters and re
ports City Engineer Shedd and Com
mlSslOneT oullt SApiaihSu tuc tcChhiS
points in answer to the numerous ques
tions of the committeeman and a genera
discussion followed. DIR. Chaplin Of thu
commission said that, although he pre-
ferred a natural filter to non
at all, he was still in favo
OF the mechanical system. Mr.. Shedt
said, by way of reply, and bringing on
the fact that a mechanical filtration
plant involved the use of alum
that a great many of tn
local physicians has expressed to him
sense of satisfaction that Providence wa
apt to secure a fine water supply withou
tho use of alum and that he had been sur
prised to find the objection to that min
eral was so general.
Alderman Mccarthy said that he hopes
that the construction work might b
done by Providence people, and in tn
resolution finally passed there was tn
provision that the work be done by con
tract or otherwise.