Evening times-Republican. [volume] (Marshalltown, Iowa) 1890-1923, 1914-08-12
Ford Explains
Sediment in Water

The presence Of sediment in the city
water, which has been roilE at times
during this summer. has caused in
quiry to be made as to the cause and II
the sediment was dangerous to health.
The city water is much clearer now
than it was few weeks ago. and the
reason that the water now carries a
larger amount of sediment than for
merly Is because the water is being
drawn from new stratum of gravel.
During April, May, and June all of
the fiftyone wells, from which the
supply is drawn, were pulled and the
we'll points and castings We're moved
to new locations. The water that is
drawn from this new and deeper
gravel bed carries iron IN solution and
causes the yellow sediment seen at
times in the water.
E. A. Ford. who was employed to
sink the new wells, says that none of
the we'll points were put into yellow
clay. In fact none of them even touch
clay, except one or two toward the
Forth end of the field. that are in hard
pan. blue clay, a foot or two This
CiCS contains no NdleI- dll't beCauSe II
does not more than twenty of the old
Wells at the north end of the field We're
abandoned and the new wells to take
their places We're sunk farther south,
where the gravel deposit is deeper, and
the water supply more abundant.
According to the citys data the
gravel bed in the north end of the field
was the deepest. Ford found this not
to be true, so with the consent of the
city the north wells ware moved south
and sunk in three rows where the
gravel was found to be deepest. The
old wells averaged about thirty-two
feet in depth. The nev' wells were
sunk 70 an average depth of thirty
eight feet. but none of them was sunk
into shale or mud. Ford says that his
experience gained by drilling wells in
the county, as well as the state geologi-
cal survev. shows that no shale is
found in this vicinity az a lesser depth
of from 80 to 200 feet.
In some cases the holes for the wells
We're sunk much deeper than the
points We're placed, and that the deep
err borings. except in the north end of
the field. showed a much greater depth
of gravel than was penetrated for the
Well points.
A detailed record of the borings for
each we'll is on file in the city clerks
office. These show that Ford bored
thru surface soil of clay running
from fifteen to twenty five feet deep,
before striking sand and gravel This
stratum was penetrated to depths
ranging from eleven to twenty three
feet. From this gravel the water is
being drawn. But before the suction
pipes were put down into the wells the
holes We're cleaned out with water un-
der pressure of seventy pounds.
The yellowish iron sediment is car
ried in solution in these new area.
from which the water is drawn, and
until all Of it has been drawn from
the gravel there will be some sediment
in the water. That is Fords explana-
ton: also the explanation of Hans
superintendent of the pump
ing station.
Owing to a larger amount Of sedi-
ment in the water lately, more of it
has been deposited in the mains. and
when greater pressure is put on, in
cases Of fire, or when the consumption
Of water is exceptionally heavy. as it
has been at times recently this sedi-
ment is stirred up and carried thru the
mains.
The same condition existed. Madsen