The Ely miner. [volume] (Ely, Minn.) 1895-1986, 1937-10-14

The corroSion ills OF the Ely waite
system were most expertly explained b,
Dr. j. E. Thompson, city chemist an'
veterinarian, to the Minnesota section
of the American Waterworks association
which met in st. Paul last Thursday
Friday and Saturday.
DR.. Thompson informs us that hi
paper was generally discussed and tina
his diagnosis was accepted at the meet
ing most heartily The pros and CON
were rehashed from every angle as th'
case fitted many other cities in thu
states besides Ely. He also stated tina
supply agents having various prepare.
lions to cure the corrosion evil were or
the spot advertising their wares.
DR.. Thompson uses many technical
terms in his diagnosis. For instance il
will be noted that PHI is an important
factor and that water with PHI of 81
dissolves only a trace of iron whereas
water with PHI 60 is harder on the
pipes by reason of heavier dissolution
of iron.
The subject discussed, Prevention OF
CorroSion in Service Lines" is Of par
ticular interest to water consumers in
this city who before treatment was be-
gun several years ago, were very much
troubled by rust in the water. This
condition has been considerably i'm
proved since treatment was begun under
the direction of Dr. Thompson who has
studied the question from every angle.
The findings of his study are given
in the address delivered at the meeting
and in which he stated:
'CorroSion of service lines produces
two primary troubles; leaks and red
water troubles. These troubles originate
from the chemical qualities of the water
which the lines convey, producing cor
rosion from within outward. Under
certain conditions corroSion of trenched
service lines takes place from without
inward, and in this paper, it is neces-
sary to consider both outside and inside
corrosion, as leaks have often been at
tributed to one cause when they are due
to the other
The PHI factor is the most important
item to take into consideration all
through the subject of corrosion.
Water with PHI of 90, for instance,
dissolves only traces of iron, whereas
with PHI of 60 diSsolves appreciable
quantities"
The City of Ely obtains its water
supply from BURNSIDE Lake. The water
has low color content most of the
year. It's hardness is practically zero.
Chemically, it has only trace of iron.
The PHI varies from 81 after spring
thaws to TO when the lake is frozen
over. This water is conveyed five miles
through fourteen inch steel pipe to
the filtration plant. The detectives at
the filtration plant are primarily, fill
tration, chlorination and adjustment of
the PHI value. No coagulation treatment
is applied
Leaks Originating From Outside
COrrosion.
Many leaks have been attributed to
the corroSiveness of the water in the
service pipes when it has been due to
the nature Of the soil conditions in
which the galvanized iron service pipes
are laid. The south side of our city
has been built up in the last five to
fifteen years. The service lines in this
district last about four to five years.
After that length of time, they COM
mence to show leaks throughout the
entire length of the pipe, from the
goose neck at the main in the alley, to
the entrance into the residence. This
district was peat bog swamp which
was drained and subdivided and the lots
sold for residential purposes. The soil
is black and contains roots and trunks
Of trees in various stages of decom-
position down to depths of four feet and
more. The soil is acid to litmuS paper
and must be lined before it will pro-
duce satisfactory garden crops and
grass. 1t appears as if placing lime in
the trenches with the back fill should
reduce this acidity of the soil and
check the corrosion of the service lines
Another type of outside corroSion is
associated with cinders. In many places
due to ledge, our service line trenches
are shallow. In order to check freezing
someone, year sage, had the idea of
covering these service lines with cinders
before back filling. This corrosion is
slower than that which occurs with
lines laid in the peat bog but it oc-
cours the entire length of the trench
where the cinders are applied.
In similar class appear to be leaks
in the service lines near the goose neck
connection to the mains. In these cases
we frequently find that the ash heap
has been shoveled in with the back
fill. Just why we see this corrosion
associated with cinders and other pro-
ducts of combustion, is not clear. II
distilled water or tap water is filtered
through cinderS no change in PHI
value is noted. Probably the conditions
are different in the filled-in trench.
Leaks Originating From the Inside,
Outward.
The leaks originating from the water
conveyed by service lines are due to
the chemical nature of the water. Up
until 1928, we made no effort to adjust
the PHI. The water as delivered to the
consumer was always distinctly on the
acid side. That year we commenced to
feed soda ash but discontinued it after
short trial because the old filtration
plant did not permit us to satisfactorily
introduce it.
Up until this time we had frequent
complaints of red water through hot
water faucets, particularly in the fall
of the year. Replacement of hot waite,
lines was frequent and the length Of
life Of hot water tanks was in many
cases short. Drip stains in fixtures
from leaky faucets, was constant in the
case of both hot and cold water dripping
but more so from hot water. Ont