Wartime Operation Problems at SeattleAuthor(s): William McNamaraSource: Sewage Works Journal, Vol. 16, No. 6 (Nov., 1944), pp. 1244-1246Published by: Water Environment FederationStable URL: http://www.jstor.org/stable/25029952 .

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1244 SEWAGE WORKS JOURNAL November, 1944

This Year 5-Year Item Average Average

Supernatant liquor

1,000 gals, daily 179.0 256.0 Per cent dry solids. 3.3 3.6

pH.. 6.7 7.0

Digestion tank temperature, F.?. 89.8 86.7

Gas production, 1,000 cu. ft. daily.. 439.0 462.7

Gas analyses Carbon dioxide, per cent.

? 33.8

Methane, per cent. ? 63.3

B.T.?. per eu. ft... ? 635.0

Cu. ft. gas per capita. ?

0.77

Incineration

Tons of wet sludge cake, daily. 73.0 74.0

Per cent dry solids in sludge cake. 37.6 37.4

1,000 lbs. dry solids in sludge cake, daily. 55.0 55.0

Per cent volatile matter in sludge cake. 49.4 43.1

Per cent CaO. 7.86 10.01

Per cent FeCl3.. 1.94 2.51

1,000 lbs. dry ash. 23.7 25.0

Per cent volatile matter in ash.. 3.73 3.57

WARTIME OPERATION PROBLEMS AT SEATTLE *

By William McNamara

City Engineering Department, Seattle, Washington

The major problem in maintenance in this war period applies simi

larly to practically all lines of endeavor and may be summarized in a

simple statement?the lack of available manpower. This may appear to be an excuse rather than a fact, but when we encounter any emer

gency we seem to come back again to the manpower question before it can be met and relieved. I have no doubt that everyone here engaged in municipal work must, like the City of Seattle, get along with 30 per cent of the labor he desires and is entitled to under his budget.

The making of necessary repairs is further complicated by some de

lay in securing material and repair parts, which situation has probably been partly due to the lack of manpower in the manufacturing plants.

We have all had our priority problems in the past but at last we in the sewage works field can point proudly to our AA-1 rating, which is the best rating given in relation to other municipal purchases. Although the manufacturers have been placed in a difficult situation in meeting our needs, they have given us their best co-operation and have helped us

avoid critical circumstances.

Another serious problem in wartime operation is the sudden increase in population which results in greater loads on the sewers and treatment

plants. One example of this is in connection with a large disposal plant operated by the Seattle Engineering Department. This plant was origi

* Presented at Pacifie Northwest Sewage Works Association Conference, Olympia, Wash

ington, May 11, 1944.

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Vol. 16, No. 6 WARTIME OPERATION PROBLEMS AT SEATTLE 1245

nally designed to handle the sewage from a certain district estimated to

have an ultimate population of 32,000 people with a flow of 8 million

gallons per day, but on this line was erected the Boeing Plant employing some 28,000 persons, the Isaaccson plant with possibly 2,000 persons and

numerous smaller industrial plants that have come into existence since

the start of the war. It can be seen that the industrial population now

served by the plant is greater than the original design population. The

sewage entering the plant is very fresh, due to its short distance of

travel and the amount of trade wastes is greatly increased. To illu

strate one phase of the problem, just yesterday we obtained 33,000 cu.

ft. of gas from our digesters, which flow being over the capacity of our

meters, is causing us considerable trouble. The normal consumption of gas for the plant and digester heating is about 10,000 cu. ft. per day and the excess burner is constantly flaming.

Recently we had an acid condition develop at the digesters and the

pH dropped into the foaming range. Upon investigation we found the

wastes responsible were coming from the Boeing factory, where the alu minum is dipped in a bath of chromic acid to give the metal a surface

that would take paint pigments in camouflage. This was brought to the attention of the Boeing engineers and correction was made which

cleared up our problem. Another problem resulted from the depositing of sponge rubber strips in the toilets at the factory which practice caused much trouble at our pumps.

We have had to make several changes at our pumping and treatment

plants in the past year. One such change was the installation of elec trical controls at the pumps so as to obtain more continuous pumping and thus relieve the stage starting devices. At the treatment plant we

have been able to reduce greatly the amount of sand reaching the di

gesters by reducing the velocity through the detritor, resulting in the removal of about 4 times as much grit as had been produced previously.

Further, we have installed automatic timing devices at our sludge pumps so that pumping of sludge from the clarifier to the digester takes place during a definite interval of every hour, whether an attendant is

present or not. The latter change has improved digester operation materially.

From a study of pump operation times at our 16 sewage pumping stations, we find that our pump capacities are such that the pumping time is very short in comparison to the rest period during filling of the

wet well. Installation and power costs would have been reduced if smaller pumps had been used so that they would operate more continu

ously. Our study of the pumping periods and the resulting adjustment of floats and controls has accomplished a reduction in our power bill of

approximately 25 per cent.

Lack of manpower is causing a real problem in connection with the maintenance of sewer systems. The proper cleaning of catch basins and inlets, the flushing and dragging of sewers and the removal of tree roots has had to be considerably curtailed. Our department now main tains about 1,100 miles of trunk and main sewers, of which some 200

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1246 SEWAGE WORKS JOURNAL November, 1944

miles require annual attention in the form of removal of roots. At

present, we are able to give this attention only once in three years. This situation, of course, has increased the liability of the City for dam ages due to blocked sewers and flooded basements.

How is this manpower problem to be met? I can only say that in our department, every man is being used where he can do the most good and that all available personnel has been apportioned to the various

divisions of the department in as equitable a manner as possible. When ever any emergency occurs in any of the divisions we all hold ourselves

in readiness to furnish all of the men and assistance that we can. I can

only recommend that you accomplish the very best results possible with what you have or can obtain without interfering with the major war

effort.

SEWAGE EFFLUENT CHLORINATION *

By Lt. E. A. Bell

Sanitary Engineer, Office of Supervising Engineer, 13th N?val District, Seattle, Wash.

In order to approach the subject of disinfection of sewage effluents, we must look back to those days when the treatment of sewage was non

existent. The use of surface supplies for potable water was, and still

is, common for cities and smaller municipalities. Disease was rampant

throughout the world and once an epidemic of cholera, typhoid or other

waterborne diseases was started, many lives were lost before the dreaded

plague had run its course?and that is the way epidemics usually ended. As human habitation began to spread out over larger areas, springs and wells also gathered pollution by seepage of wastes into the ground.

The development of water treatment units such as filters, coagulation tanks and disinfection devices arrested such disease and retarded it to a point that now a waterborne epidemic is very rare. At the turn of the

century, it became apparent that the most practical approach to the problem of pollution was removal of the source rather than an attempt to treat all water supplies as extensively as the necessity demanded.

The use of sewers for the removal of wastes dates back to the Roman

Empire, but the collection of sewage and its subsequent treatment has

occurred within the last century and has only reached its peak in the

past twenty-five years. The disinfection of the effluent is usually the

final step in rendering harmless the discharge of treated sewage into

various streams, river, lakes and other bodies of water used not only for

potable purposes, but also for bathing and the habitat of edible shellfish.

Experimentation over a period of years has demonstrated many methods of destroying bacteria in water. However, the use of chlorine

gas, in properly controlled doses, has proven not only the most effective, but also the most economical. The development of hypochlorite com

* Presented at Pacific Northwest Sewage Works Association Conference, Olympia, Wash

ington, May 11, 1944.

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