MINNESOTA DEPT. OF HEALTH 
OPERATION AND MAINTENANCE OF MUNICIPAL AND 
I LARGER INSTITUTIONAL SEWAGE AND WASTE 
TREATMENT PLANTS IN MINNESOTA Operation and Maintenance of 
Municipal and Larger Institutional 
Sewage and Waste Treatment 
Plants in Minnesota 
MINNESOTA DEPARTMENT OF HEALTH 
Section of Environmental Sanitation 
Division of Water Pollution Control 
1947 
7982 6-17-48 1M Operation and Maintenance of 
Municipal and Larger Institutional 
Sewage and Waste Treatment 
Plants in Minnesota 
MINNESOTA DEPARTMENT OF HEALTH 
Section of Environmental Sanitation 
Division of Water Pollution Control 
1947 
7982 5-17-48 1M Contents 
Page 
Introduction 5 
Section I—Grit Chambers 9 
Section II—Coarse Screens and Cutting Screens 10 
Section III—Measuring Devices n 
Section IV—Fine Screens 12 
Section V—Imhoff Tanks 13 
Section VI—Primary Settling Tanks 19 
Section VII—Separate Sludge Digestion Tanks 20 
Section VIII—Sludge Conditioning Equipment 21 
Section IX—Dosing Apparatus 22 
Section X—Trickling Filters 23 
Section XI—Secondary or Resettling Tanks 24 
Section XII—Sludge Drying Beds 25 
Section XIII—Chlorination Units 26 
Section XIV—Plant Operation Report Form 28 
Appendix I—Simple Laboratory Method for the Control of the 
Operation of Sewage Treatment Plants 32 
Appendix II—Hazards and Safety Measures in Sewage Treatment Plants 37 
Appendix III—Discharge in Gallons per Minute Over Right-Angled 
V-Notched Weir 40 
Appendix IV—State Water Pollution Control Act 41 
Appendix V—Municipalities Having Sewer Systems with Sewage 
Treatment Plants 48 
Appendix VI—References 55 The Operation and Maintenance of Municipal and Larger Institutional 
Sewage and Waste Treatment Plants in Minnesota 
Introduction 
This information has been prepared as an aid to municipal officials who 
are responsible for the operation of sewage treatment plants in Minnesota, 
and as a guide to plant operators in the care of their plants. Local conditions 
may alter somewhat the operating procedure, but, in general, this information 
will be found applicable to the various treatment units described. 
A sewage treatment plant represents the investment of a considerable 
sum of money expended primarily for the purpose of preventing pollution of 
the waters of the State. The degree of success attained in the operation of such 
a plant is to a large extent a direct result of, and in proportion to, the in- 
telligence and effort expended. 
The State Water Pollution Control Act, Laws of 1945, Chapter 395, defines 
pollution and waters of the State as follows: 
“ ‘Pollution’ means the contamination of any waters of the state 
so as to create a nuisance or render such waters unclean, or noxious, 
or impure so as to be actually or potentially harmful or detrimental 
or injurious to public health, safety or welfare, to domestic, commer- 
cial, industrial or recreational use, or to livestock, wild animals, birds, 
fish, or other aquatic life.” 
“ ‘Waters of the state’ means all streams and lakes, including all 
rivers and lakes bordering on the state, marshes, watercourses, state, 
county, town or judicial drainage systems and other bodies of water, 
natural or artificial, public or private, of such character that the pollu- 
tion thereof may create a nuisance or be either actually or potentially 
harmful or detrimental to the public health, safety or welfare, or to 
domestic, commercial, industrial or recreational use, or to livestock, 
wild animals, birds, fish, or other aquatic life.” 
Pollution of the waters of the State resulting from the discharge of 
domestic sewage or industrial waste by a municipal sewer system has been 
held to be the responsibility of the municipality (Huber vs. City of Blue Earth, 
Minnesota Supreme Court, November 1942). 
In addition to having a clear idea of the operating procedure, it is essential 
that officials understand the limitations of the processes used in the plants under 
their control. Plate I shows the reduction in strength which may be expected 
to be obtained by passing sewage through various treatment plants under 
satisfactory operating conditions as measured by the five-day biochemical 
oxygen demand test. By definition, the biochemical oxygen demand of a 
polluted water is the amount of oxygen, expressed in the usual concentration 
5 PLATE-I 
COMPARATIVE REDUCTION IN STRENGTH OF SEWAGE 
ACCOMPLISHED BY VARIOUS TYPES OF TREATMENT UNITS 
PERCENT REDUCTION IN 5 DAY B.O.D. 
USED FOR DISINFECTION OF EFFLUENT 
PRIMARY UNITS 
SECONDARY UNITS 
SAND FILTER 
- SLANT INDICATES VARIATION IM DEGREE TREATMENT 
5. TRICKLING FILTER AND 
RESETTLING TANK WITH 
2 OR 3 
6. SAND FILTERS PRECEDED 
BY 4 OR 5 
7. CHLORINATION PRECEDED 
BY 2. 3,4,5, OR 6 
TREATMENT UNITS 
3. MECHANICAL CLARIFIER 
WITH SEPARATE SLUDGE 
DIGESTION. 
4. ACTIVATED SLUDGE 
WITH 2 OR 3 
LEGEND 
I. SEPTIC TANKS 
2. IMHOFF TANKS 
6 units, required to bring that water into a state of final oxygen equilibrium in 
the presence of oxygen, bacteria, and other microscopic life, and the residual 
organic products.* This test is frequently used to express the relative strength 
of polluted waters. 
Treatment works or disposal systems are designed primarily for the 
treatment or handling of sewage or industrial wastes. Storm water and roof 
drainage should be excluded as far as possible. Data on the design and 
capacity of plants are contained in the report on the examination of plans 
made by the State Department of Health, Division of Water Pollution Control, 
and forwarded to the municipality with the approved plans. 
The issuance of permits by municipalities for admission of industrial 
wastes to the sewerage system should be given thorough consideration. The 
industrial wastes that are most frequently encountered in Minnesota are those 
from creameries, milk plants, locker plants, rendering works, canneries, sugar 
refineries, packing plants and paper mills. The strength of some of these 
wastes, as compared with domestic sewage, is shown in Plate II. 
Excessive quantities of industrial wastes may overload the pipe-collectioi 
system or the sewage-treatment plant. The strength or chemical characteristics 
of the waste may cause deposits to occur in the pipe line and develop offensive 
odors, or may so affect the ordinary processes in the treatment plant as to 
render them ineffective. Where there is any question as to the effect of any 
particular industrial waste, it is desirable to obtain competent advice before 
any permit for a connection is issued. 
To assist the operator in obtaining proper operation and maintenance the 
following data should be available at all plants: 
i. Complete construction plans of the plant as it was built. 
2. Complete description of each piece of equipment with a list of spare 
parts and manufacturers instructions for operation and maintenance. 
3. Maintenance schedule for each piece of equipment showing the time 
and the person responsible for necessary lubrication, adjustments and in- 
spections. 
4. Daily operating report. 
Sufficient time should be spent at the plant to permit the operator to 
keep all units in operating condition, do necessary maintenance and repair 
work, make necessary tests and keep proper records. Good housekeeping is 
essential both inside and outside the plant. Where difficulty is experienced 
in financing the operation by general funds, it is suggested that consideration 
be given to the use of sewer service charges as provided for (Chapter 211, 
Laws of 1935, and Chapter 57, Laws of 1937). 
*Public Health Bulletin No. 173, the Oxygen Demand of Polluted Waters. 
7 5 DAY B.O.D. —R RM. 
COMPARATIVE STRENGTHS OF 
TYPICAL INDUSTRIAL WASTES 
ORDINARY RANGE 
PLATE - II 
DOMESTIC SEWAGE 
PACKING PLANT 
CANNING PLANT 
CREAMERY 
WASTES 
8 Section I 
GRIT CHAMBERS 
i. Description and Purpose 
A grit chamber consists of a small chamber, usually long and rectangular, 
in which the velocity of the sewage is reduced to such an extent (approximately 
one foot a second) that heavy inorganic suspended matter such as coal, grit, 
sand and gravel, etc., may be settled out. The removal of this material tends 
to prevent excessive wear or clogging of pumps and equipment. Trouble 
caused by accumulation of this material in subsequent units of the plant is 
also reduced. 
2. Operation 
A. In small plants grit is removed manually at predetermined intervals 
while larger plants have mechanical grit removal equipment which operates 
intermittently or continuously depending upon individual plant conditions. 
B. Accumulation of grit should be removed before efficiency of the 
operation of the unit is reduced. 
C. Disposal of the collected material should be made in one of the 
following manners; 
i. Bury, if manually removed, covering by at least six inches of earth, 
either by ploughing under the soil trenching. In winter 
it may be placed in trenches, treated with chloride of lime or other 
disinfectant and covered with earth in the spring as early as 
possible. 
2. Use as fill mechanically removed and washed grit. 
9 Section II 
COARSE SCREENS AND 
CUTTING SCREENS 
3. Description and Purpose 
Coarse screens or cutting screens are provided to prevent large objects 
such as rags and sticks, etc., from clogging or damaging pumps, piping, small 
channels or other equipment. Bar screens consist of a grid of steel bars spaced 
approximately two to two and one half inches apart, center to center, placed 
in the influent channel of the plant inclined at an angle in the direction of 
flow of the incoming sewage. Cutting screens have revolving drums or 
cylinders on which are located cutting blades. These screens (electrically 
driven) are placed in the influent channel and eliminate the necessity of 
removing screenings by cutting all solids so they can pass through the screens 
with the sewage. 
4. Operation 
Screenings, unless properly disposed of, are frequently a serious source 
of nuisance at a treatment plant because they decompose readily, giving off 
obnoxious odors. They will also encourage the breeding of rats and flies 
unless properly cared for. 
A. If bar screens are used remove the screenings daily, or oftener if 
necessary, to prevent clogging the screen and consequent backing up of 
sewage in the outfall sewer. 
B. Prompt disposal of the screenings should be made in one of the 
following manners; 
1. Bury, covering by at least six inches of earth either by ploughing 
under the soil or shallow trenching. In the winter, they may be 
placed in trenches, treated with chloride of lime or other dis- 
infectant and covered with earth in the spring as early as possible. 
2. Incinerate after draining. 
C. Clean the screen chamber, removing all accumulated sludge and 
grease, at least once a week. 
D. Small quantities of screenings can be conveniently handled in tightly 
covered galvanized garbage cans. 
10 Section 111 
MEASURING DEVICES 
5. Description and Purpose 
Weirs, Parshall flumes, Venturi tubes and flow meters are most frequently 
used to measure flow of sewage. These devices are usually installed either in 
the influent channel or effluent channel of the plant. They may also be installed 
to determine the quantity of sewage recirculated through the plant units. To 
permit intelligent operation of a sewage treatment plant it is essential that 
some method of determining flow through the plant be available. 
Flow, if necessary, may also be determined by timing the operation of 
pumps and calculating their output or by counting the dosing cycles of the 
dosing apparatus if such equipment is used in the plant. 
6. Operation 
A. Measuring devices must be kept clean of deposits which may 
accumulate. 
B. Where recorders are used charts must be changed regularly and the 
recording device must be properly maintained. 
11 Section IV 
FINE SCREENS 
7. Description and Purpose 
A fine screen (a continuously revolving drum covered with a fine-mesh 
screen) removes a part of the suspended solids, as well as coarse material, 
thereby relieving the load on subsequent treatment units. 
8. Operation 
A. Fine screens are usually cleaned continuously and mechanically either 
by water, air or revolving brushes. All moving parts should be oiled or 
greased sufficiently to keep them in proper working condition. 
B. The solids retained by the screen may be disposed of in one of the 
following ways: 
1. Convey the solids to the digester or chemical mixing vats and 
treat with other solids. 
2. Dewater and burn the solids. 
3. Bury, covering by at least six inches o£ earth, either by ploughing 
under the soil or shallow trenching. In the winter they may be 
placed in trenches, treated with chloride of lime or other dis- 
infectant and covered with earth in the spring as early as possible. 
12 Section V 
IMHOFF TANKS 
9. Description and Purpose 
Imhoff tanks, sometimes known as two-story settling tanks, have an upper, 
or flowing through, compartment for primary settling of the sewage to remove 
the settleable suspended solids. A lower or digestion compartment is provided 
to liquefy, gasify, and digest the settleable solids. (See Plate III) 
A trapped slot between these compartments enables the solids which are 
settled out of the sewage in the upper chamber to pass into the lower or sludge- 
digestion compartment. This trapped slot also prevents the gases produced 
by decomposition in the digestion compartment, together with gas-laden particles 
of sludge, from getting into the settling compartment and from coming in 
contact with the settling sewage. These gases and gas-laden particles are 
deflected by the sloping bottom of the sedimentation compartment and rise in 
the scum chamber, or gas vent, where the gases escape and a large part of 
the previously gas-laden material settles again. In a tank which works prop- 
erly, the gases given off should be inoffensive with a slightly tarry or gassy 
odor. 
10. Operation 
A. SEDIMENTATION COMPARTMENT 
1. Grease and scum in the sedimentation compartment should he re- 
moved daily. This is best accomplished by the use of a dish-shaped perforated 
skimmer (see Plate IV). Such grease and scum should be promptly disposed 
of by burying or burning. Where objectionable conditions are not likely to 
develop, the grease and scum may be placed in the gas vents. 
2. The sides and slopes of the sedimentation compartment should he 
carefully scraped with a rubber squeegee (see Plate IV), and all solids pushed 
down through the slots at least every week. 
3. The slot in the bottom of the sedimentation compartment must be 
kept open and free from obstruction of any kind. Every other day the slot 
should be cleaned by the use of a chain drag (see Plate IV), taking care 
to traverse the entire length of the slot. 
4. Failure to follow carefully the foregoing operating procedure will 
usually result in an effluent of inferior quality and, where a trickling filter is 
used, there will be deposits and accumulation of solid material on or in such 
filter, due to grease, scum or sludge being carried through the tank. 
5. Where the design of the tank will permit, the direction of flow 
through the sedimentation compartment should be reversed at least once a 
month, in order to distribute the solids uniformly in the digestion or sludge 
compartment. 
13 BAFFLE 
SLUDGE PIPE 
INLET 
SEDIMENTATION 
COMPARTMENT 
OAS VENT 
SLOTS 
' SLUDGE " 
COMPARTMENT 
SECTION OF CIRCULAR SETTLING 
TANK,TWO STORY OR IMHOFF TYPE 
PLATE III 
14 B. GAS VENTS OR SCUM COMPARTMENT 
The scum in the gas vent should be thoroughly broken up at least once 
a week so that the gases from the digestion or sludge compartment will escape 
easily. This may be accomplished by one of the following means: 
1. Break up the scum with a hoe, rake, or other suitable tool. 
2. Hose the scum in the gas vents with water under pressure. 
3. Keep the scum in the gas vents saturated with sewage from the 
sedimentation compartment, or preferably with liquor from the 
digestion compartment, by using a small pump or air-lift device. 
4. Punch holes through the scum at two-foot intervals with a 
wooden pole, three inches in diameter and eight to ten feet long. 
5. Treatment of the scum in the gas vents daily with hydrated lime 
at a rate of about 10 pounds per 1000 population has been helpful 
in controlling excessive scum formation and to aid in maintaining 
the pH value of the digesting sludge at from 7.2 to 7.6. 
6. The scum may be removed and dried in a sludge drying bed if 
its depth approaches two or three feet. 
C. SLUDGE COMPARTMENT 
1. The height of the sludge in the sludge compartment should be de- 
termined at the inlet and the outlet ends of the tank at least once a month. 
For this purpose, it is most desirable and satisfactory to use a pump. It is not 
recommended that the plate or disc method be used except for the final 
settling tank. Any of the following are suitable methods for measuring the 
depth of the sludge. 
a. A pitcher pump provided with a rubber suction hose, weighted 
on the end and the length marked on the hose at intervals of 
two feet (see Plate IV), measuring from the weighted end toward 
the pump. The hose is gradually lowered through the slot in the 
sedimentation compartment, meanwhile pumping constantly, and 
the length of immersed hose when sludge first comes through the 
pump is determined. When sludge is encountered, the pump will 
usually “choke” before the sludge appears. 
b. A pitcher pump may also be used with a rubber suction hose, 
weighted on the end by a four-foot length of steel pipe as an 
integral part of the pump suction line. This suction hose may be 
graduated and marked as above and the determination of sludge 
made in the same manner except that the hose is lowered through 
the gas vent instead of the sedimentation compartment slot. 
15 SKIMMER 
SQUEEGEE 
SCUM HOE 
SLOT CLEANER 
PITCHER PUMP 
SLUDGE SOUNDER 
IMHOFF TANK TOOLS 
AND 
SLUDGE SOUNDERS 
PLATE -IS c. The sludge depth may also be determined by the use of an iron 
plate or weighted wooden block, about 12 to 18 inches square, 
attached to a wire or chain (see Plate IV) and lowered through 
the gas vent. The plate or block will stop when the sludge is 
reached and the distance from the surface to the sludge level is 
determined by the graduated wire or chain by which the device 
is lowered. 
2. Sludge should be removed in small amounts at frequent intervals 
(1-2 months during summer) rather than in large amounts at longer intervals 
and should be removed whenever the sludge depth approaches within 18 inches 
of the slot in the sedimentation compartment. It should be removed at a 
low regular rate to avoid the formation of channels through the sludge in 
the compartment and the consequent withdrawal of partially digested sludge 
or liquid above the sludge. 
3. If the sludge does not flow readily, it may be started by one of 
several methods: 
a. Agitate with water under pressure through perforated water pipes 
in the bottom of the sludge compartment, if such pipes are avail- 
able. 
b. Apply water pressure through hose immersed into the sludge 
compartment or through the sludge riser pipe. (Because of the 
possibility of contaminating the water supply used as outlined in 
paragraph a. and this paragraph, there should be no direct con- 
nection made with any source of water used for domestic purposes.) 
c. Agitate around sludge inlet with long rods through the sludge 
riser pipe. 
4. Avoid the withdrawal of all the sludge from the tank. Leave suffi- 
cient digesting or “seed” sludge to prevent the difficulties incidental to start- 
ing a new or completely cleaned tank. Usually not over half the depth of 
sludge in the tank should be removed at any one time. 
5. After they have been used, the sludge pipes should be flushed out 
and refilled with water or sewage to prevent the sludge from hardening and 
clogging them. 
n. “Foaming” in Imhoff Tanks 
“Foaming” is a term used to describe the condition which develops some- 
times in Imhoff tanks, whereby gas, froth and scum rise in the scum com- 
partment or gas vent and carry over the wall into the sedimentation com- 
partment. Besides being unsightly and disagreeable, this foaming seriously 
interferes with the efficiency of the plant. Dark scum and solid material may 
17 be carried into the sedimentation compartment and be discharged in the tank 
effluent. This will cause an unsatisfactory tank effluent and an abnormal 
load on subsequent treatment units. 
There are a number of possible causes for “foaming” such as industrial 
wastes like milk or cannery wastes, “mash” or “wine” wastes, drawing out 
too much sludge at one time, or increased temperature in the sludge com- 
partment. Foaming is frequently associated with an “acid” condition of the 
smdge and in such cases may be minimized or corrected by treatment to 
counteract the acidity. 
When foaming persists, it is advisable to seek the advice of an ex- 
perienced sanitary engineer. 
Following are some simple treatments which may, under certain condi- 
tions, remedy or improve the condition: 
A. Draw a quantity of sludge. 
B. Hose the gas vent area with water under pressure. 
C. Cut the tank out of service if possible and allow it to rest. 
D. Paddle the foam with a long-handled hoe. 
E. Add hydrated lime through the gas vents at daily intervals. 
F. Treat the raw sewage with chlorine at rates of 20 to 50 pounds 
per million gallons. 
18 Section VI 
PRIMARY SETTLING TANKS 
12. Description and Purpose 
Primary settling tanks are either rectangular or circular in shape usually 
having a relatively shallow liquid depth of six to eight feet. They may be 
constructed with plain hopper bottoms or be equipped with mechanisms for 
the collection of sludge. They are designed to remove a large part of the 
suspended solids by settling without anaerobic or septic decomposition taking 
place within the tank. 
13. Operation 
A. The settled solids or sludge should be either continuously removed 
to the sludge-digestion tanks by mechanical equipment, or should be com- 
pletely removed at least once a day to the sludge-digestion tanks from the 
settling tanks which are not equipped with a continuous-removal equipment. 
B. Septic action in the plain settling tanks as evidenced by “gassing” 
or an appreciable increase of the settleable solids in the settling tank effluent 
should be prevented by prompt and regular removal of sludge to the sludge- 
digestion tanks. 
C. Grease and scum should be removed daily, using a perforated 
skimmer (see Plate IV), and the tanks should be maintained in a clean 
condition at all times. 
19 Section VII 
SEPARATE SLUDGE-DIGESTION 
TANKS 
14. Description and Purpose 
Separate sludge digesters consist of large tanks with fixed or floating 
covers, heated or unheated, used singly or as primary and secondary units. 
These tanks are used to decompose, liquefy, or gasify solids transferred to 
them from plain settling tanks and to produce an innocuous material which 
can be disposed of readily. 
15. Operation 
A. The contents of the tank should be stirred or agitated at frequent 
intervals by recirculation or other means to assure proper “seeding” of the 
fresh solids and to afford rapid and efficient digestion. Such stirring also 
lessens the possibility of “foaming” difficulties and excessive scum formation. 
B. Where heating coils or other means of heating the contents are avail- 
able, the temperature should be maintained at 800 to 90° F. 
C. The amount of raw sludge added daily should not be over one- 
twentieth of the amount of “ripe” sludge in the tank, on the basis of the 
dry solid content. 
D. When unusual conditions, such as “foaming,” “acid,” sludge, etc., 
develop and the operator is not experienced in handling such conditions, an 
experienced sanitary engineer should be called in and his recommendations 
followed. 
E. Care must be used in removing digested sludge to avoid the re- 
moval of such a large amount that the ratio of “ripe” sludge to raw sludge 
added drops below twenty to one. 
F. The reaction of the sludge should be maintained at a pH value 
of 7.2 to 7.6. The addition of lime or other alkaline reagents to the sludge 
will increase the pH value of the sludge. Satisfactory results are occasionally 
obtained with slightly lower values. 
20 Section VIII 
SLUDGE CONDITIONING 
EQUIPMENT 
16. Description and Purpose 
This equipment consists of a small mixing tank and mixing device. Raw 
sludge is pumped to the mixing tank and certain chemical coagulants are 
added and mixed with the sludge to facilitate separation of the water when 
the sludge is drawn to sludge beds. In larger plants chemically conditioned 
sludge is dewatered with a rotary drum type vacuum filter and then in- 
cinerated or disposed of in the same manner as sludge from sludge drying 
beds. 
17. Operation 
A. Sludge should be treated with chemicals and placed on drying beds 
promptly after it is pumped from the settling tanks. 
B. The quantities and proportions of chemical must be determined by 
practical experience as well as the necessary length of time of mixing required. 
C. Chemicals for sterilizing sludge may be added to the sludge at 
the same time as the coagulants. 
21 Section IX 
DOSING APPARATUS 
18. Description and Purpose 
Dosing apparatus usually consists of a dosing tank and siphon and pro- 
vides for periodic and uniform distribution of the sewage on low rate or 
conventional type filters or on sand filters. 
19. Operation 
A. The mechanical equipment should be kept in perfect working order. 
Moving parts should be regularly oiled or greased. 
B. Pipes and air lines should be kept open and free from obstructions 
and accumulations of any sort. 
C. Any mechanical breakdown should be repaired immediately. 
D. Where there are two units or where it is possible to cut out a unit 
without seriously interfering with subsequent treatment, a complete clean- 
ing of the dosing tank should be made weekly, removing all grit and sludge 
deposits and all growths and deposits on pipes and walls. This is necessary 
in order to prevent clogging of the nozzles in a trickling filter unit. In the 
event that it is not feasible to cut out a unit, the walls and pipes should be 
cleaned as carefully as possible by means of an inverted scraper, taking care 
that solid material does not enter the dosing tank outlet. 
22 Section X 
TRICKLING FILTERS 
20. Description and Purpose 
Trickling filters usually consist of concrete structures either rectangular 
or circular in shape containing six to eight feet of filter material of selected 
size and quality. Sewage may be applied over the surface of the filter by 
means of rotary distributors, mechanical discs, fixed nozzles or tip troughs. 
Trickling filters are the most common type of secondary treatment and are 
preceded by primary settling tanks or fine screens. They are used to stabilize 
or oxidize, with the aid of biological action, organic matter, and to remove 
solids which have not been removed by preceding treatment. 
21. Operation 
A. Spray nozzles or distributor orifices should be inspected daily. All 
clogged nozzles and orifices should be cleaned and all broken ones replaced. 
Special care should be exercised during winter months to prevent freezing. 
B. The distribution piping or rotary distributor arms should be flushed 
once a week. This may be accomplished by removing the end nozzles on 
laterals or by opening the end gates on distributor arms. 
C. The nozzles and distributor arms and orifices should be kept in 
adjustment to assure equal distribution over the entire filter surface. 
D. The surface of the filter bed should be kept free from vegetable 
growths. 
E. The formation of ponds or “pooling” on the surface of the filter 
bed may be remedied or prevented by one of the following methods; 
1. Flush the surface of the filter with a firehose. 
2. Rake or fork the surface. 
3. Punch holes through the top layer of the filter medium with iron 
bars. 
4. Make heavy applications of chlorine or chlorinated lime to the 
filter-bed influent at the dosing tanks for short periods once a 
week. 
5. Put units out of service occasionally for a period of twelve to 
forty-eight hours except during cold weather. 
F. The presence of large numbers of filter flies may be controlled by 
periodic flooding of the filter beds, by heavy doses of chlorine or D.D.T. in 
certain forms in the sewage applied to the beds, or by dosing sections of the 
filter at excessive rates for short periods of time. 
G. The underdrains should be flushed out regularly with water hose 
or other suitable flushing device, if the filters are so constructed as to make 
this possible. 
23 Section XI 
SECONDARY OR RESETTLING 
TANKS 
22. Description and Purpose 
Secondary or resettling tanks are similar to primary settling tanks in 
design and are used to remove the settleable suspended solids which are 
present in the effluents from trickling filters. 
23. Operation 
A. The sludge should be removed frequently to prevent septic action 
and gasification of the solids which are settled out in the tank. Once each 
week should be the minimum in the winter and at least daily in the summer 
months. 
B. The sludge should ordinarily be discharged into the primary settling 
tanks, preferably into the tank inlet. 
24 Section XII 
SLUDGE DRYING BEDS 
24. Description and Purpose 
Sludge drying beds consist of large drained beds of layers of sand and 
gravel onto which digested or chemically conditioned sludge is discharged 
to reduce its water content so that it may be handled readily. 
25. Operation 
A. Sludge beds should not be filled to a depth of over twelve inches 
or to such a depth that the sludge cake cannot be removed within two weeks 
in good drying weather. 
B. If drying is slow because of clogged beds, a thin layer of material 
(usually sand) should be removed from the surface of the drying bed and 
replaced with clean material. 
C. The surface of the drying bed should be kept clean and free from 
all previously discharged sludge. Never discharge wet sludge on partially 
dried sludge. 
D. The surface of the sludge drying beds should be kept level, to afford 
an even distribution of sludge over the surface of the bed. 
E. Remove the sludge just as soon as it may be handled with a fork. 
F. Dried sludge may be used for fill, may be buried or spread upon 
the ground where it will not be carried into a stream or watercourse by rain. 
G. In many communities, the sludge is readily disposed of by giving 
or selling it to nearby farmers for use as a soil conditioner. It is not advisable, 
however, to use it for the fertilization of fruits or vegetables which may be 
eaten uncooked. 
25 Section XIII 
CHLORINATION UNITS 
26. Description and Purpose 
Chlorination units consist of a chlorinator and a chlorination chamber 
or contact tank in which chlorine is added to the sewage and contact is 
maintained for a period of thirty minutes to prevent bacterial contamination 
of streams or other bodies of water used for domestic water supply or for 
recreational or industrial purposes. 
The effective chlorination of sewage or sewage effluents depends upon the 
presence of sufficient quantity of chlorine in all portions of the sewage for a 
time long enough to provide the necessary period of contact between the dis- 
infectant and the bacteria. Any interruption in the chlorination process will 
be followed at once by the delivery of unchlorinated sewage even though other 
portions of the sewage may have been properly disinfected previously. When 
chlorine is added to sewage, it reacts with the organic matter in the sewage and 
is absorbed. The rate of this absorption depends upon the temperature of the 
sewage, the amount of organic matter, and the dose of chlorine. The first of 
these factors cannot be controlled so the net result has to be ascertained by 
tests for residual chlorine in the sewage which will indicate whether the 
chlorine rate should be increased or decreased. 
Residual chlorine in sewage will react with a prepared solution of ortho- 
tolidin to form a yellow color, the intensity of which is proportional to the 
amount of residual chlorine in the sewage. In making this test, the intensity 
of the color is compared with standard colored solutions which are prepared 
to match the colors produced by graded amounts of residual chlorine. The 
turbidity of the sewage is compensated for by placing a bottle of the sewage 
in front of the standard color solution as described later under Appendix I. 
Experience has shown that most sewages can be effectively chlorinated 
when chlorine is added in sufficient quantity to produce a residual chlorine 
concentration of at least 0.5 parts per million in fifteen minutes after the 
chemical is introduced into the sewage. Thus, the dose of chlorine is varied 
in accordance with the rate of absorption of the disinfectant as indicated by 
the amount of residual chlorine remaining at the end of the fifteen-minute 
contact period. 
The strength of any sewage varies greatly with seasonal changes, with the 
days of the week, and during the hours of the day. The amount of chlorine 
required varies accordingly. Unless it is possible to make regularly frequent 
tests throughout each, a series of tests should be made to determine what time 
of day the most concentrated and heaviest doses of sewage reach the point of 
chlorination, and, thereafter, tests should be made at that time every day. This 
occurs some time during the forenoon in most plants. It is unwise to attempt 
to adjust chlorine dosage too closely; chlorine is comparatively cheap and an 
overdose will seldom do any harm. 
26 27. Operation 
A. Chlorine should be applied in such quantity that there will be a 
residual of at least 0.5 parts per million as determined by the ortho-tolidin test 
after fifteen minutes contact with the sewage effluent. 
B. The test for residual chlorine should aways be made at the time when 
the sewage effluent is the strongest or when it requires the largest amount of 
chlorine for treatment. 
C. The chlorine tank should be weighed each day at the same time to 
ascertain the amount of chlorine used. 
D. The chlorine must be applied continuously in the proper quantities. 
E. Before connecting a new chlorine cylinder to the control apparatus, 
blow off some of the chlorine from the new cylinder into the air in order to 
prevent clogging of the apparatus. 
F. Examine the chlorine apparatus daily and if any trouble is found 
which cannot be corrected by the operator notify the manufacturer at once. 
G. It is not advisable to draw more than forty pounds of chlorine from 
any one cylinder in a twenty-four hour period because of the danger of “freez- 
ing” and slowing up the chlorine flow. If more chlorine is necessary, two or 
more tanks should be connected and used in parallel. 
H. The operator should always have on hand a stock of the usual 
replaceable parts for the chlorine apparatus, and an extra supply of chlorine 
tanks. 
I. Leaks in the chlorine apparatus may be detected by the formation 
of white fumes when tested in the immediate vicinity with the vapors from 
an ammonia solution. (Household ammonia is satisfactory.) 
J, During cold weather heating facilities should be provided to maintain 
a temperature of 6o° F., and never less than 50° F., in order to prevent so-called 
“freezing” in the chlorinator and stoppage of the chlorine flow. 
K. Chlorine is a liquid when under pressure in the cylinders and is an 
irritating gas which is heavier than air when released. It may produce serious 
after-effects if inhaled. A satisfactory gas mask should be available at all plants 
where chlorine is handled. 
27 Section XIV 
PLANT OPERATION REPORT 
FORM 
28. Description and Purpose 
A report form for a sewage treatment plant is a chart on which certain 
readings, measurements, conditions and duties performed concerned with the 
operation of the plant are recorded. 
Regardless of the size of the plant or the number of employees, certain 
operation records should be kept. keeping of a report form is essential 
for the intelligent reporting of plant operations, and in establishing the need 
for sufficient funds for necessary repair and replacement of equipment. Plants 
should be under the direct supervision of a superintendent or designated mem- 
ber of the council to whom all reports should be made. 
The following report form and explanation may serve as a guide in the 
preparation of a form for individual plants.* 
Representatives of the Department of Health are available for consultation concerning neces- 
sary reports for individual plants. 
28 REPORT QT/ OPERATION OP SEWAGE TREATMENT PLANT AT 
For Month ot. 
/P_ 
Time 
Hours 
at Plant 
Wbother 
Wind 
GENERAL 
Umpenature 
\ Skimmed 
5/ots 
. Cleaned 
I F/orv 
Reversed 
Scum 
Broken 
Scum 
Deplh 
S/udge 
Deplh 
pH 
Sludge 
tMHOFF TANK. 
From Tank 
CuFt. 
Co/or 
Odor 
From Bed 
Cu.Ft 
Drying 
Time 
SLUDGE. REMOVED 
DOSING TANK 
Counter 
Reading 
Cleaned 
Filling 
Time 
TRICKLING filter 
ttozz/es 
Cleaned 
Underdrdns 
Cleaned 
Filter 
Pooling 
Filter 
S/oughing 
RZS^TUNO' 
Skimmed 
Sludge 
Removed 
Cleaned 
SETTLBABLB SOL!PSl| 
Ec.pST Lire* 
Plant 
Influent 
Tank 
Efffuent 
Filter 
Effluent 
P/ont 
Effluent 
Temp £ff. 
stability 
Filler 
Eff/uen! 
p/ant 
Effluent 
SETT LINS TANK 
Skimmed 
Mechanism 
Operated 
5/tx/ge 
Removed 
Scum 
Depth 
S/udge 
Depth 
Timptrofurt 
Hbter 
Temperature 
Study* 
pft 
S/udge 
&as 
Cu. Ft 
3LUD6B D/QESTOR 
Weight 
Tanks 
Rounds 
Used 
Rah 
Day 
Rote 
-tf'jM - 
Residua/ 
Effluent 
Time 
CHLORlNA T/or/ 
Cots 
'Air 
Sewage 
Sewage 
Flow 
Semen 
Cleaned 
Units 
Bypassed 
JRemorAs 
4C. Quantity Screenings dotty disposed of by 
4f- S/udge from bed is disposed of by 
42 Conditions be/ow plant act tie t 
43 Afethod measuring f/ow 
44 Power Consumption 
46. Genera / Rem or ks 
Operator. 29. Explanation of the Information Which Should Be Recorded on the 
Sheet Entitled “Report on the Operation of Sewage Treatment 
Plants” 
Column 
Number 
1. Give the time of day that the observations are made. 
2. State the number of hours spent at the plant by the operator. 
3. Weather conditions; e.g., F=Fair, C=Cloudy, R=Rainy, S=Snow. 
4. Direction from which the wind is blowing. 
5. Air temperature outside (F. °) at observation time. 
6. Raw sewage temperature (F. °). 
7. Flow of sewage in gallons per 24 hours at observation time or if meter 
is used, total flow over 24 hours previous. 
8. Give the number of times screen is cleaned during the day. 
9. Make a cross (x) for the days when floating solids are removed from 
the surface of the settling chamber. 
10. Make a cross (x) on the days when slopes of settling compartments are 
squeegeed and the slots cleaned. 
11. Make a cross (x) on the days when the direction of flow across the tank 
is reversed. 
12. Make a cross (x) on the days when the scum in the gas vents is broken 
up. 
13. State the depth in feet of the scum in the gas vents. 
14. State the depth of the sludge in the tank in feet from the water surface 
measured once a month or more often. 
15. State the pH value of the sludge in the digestion chamber once a month 
or more often. 
16. State the number of cubic feet of wet sludge removed from the diges- 
tion chamber to the sludge drying beds. 
17. State the color of the sludge removed. 
18. State the odor of the sludge removed. 
19. State the number of cubic feet of dried sludge removed from the sludge 
drying beds. 
20. State the number of days required to dry the sludge to a condition 
suitable for removal. 
29 Column 
Number 
21. Reading of the dosing counter each day or the total number of dosing 
tank discharges (when counter is provided). 
22. Make a cross (x) on the days the dosing tank is cleaned. 
23. State the time in minutes that is required to fill the dosing tank at 
observation time. 
24. State the number of nozzles cleaned each day. 
25. Make a cross (x) on the days the underdrainage system of the filter is 
cleaned. 
26. Make a cross (x) on the days indications of pooling appear on the sur- 
face of the filter and describe under the column headed remarks. 
27. Make a cross (x) on the days when there is an unusual quantity of 
solid material discharged from the filter bed and describe under column 
headed remarks. 
28. Make a cross (x) on the days when the floating solids are removed 
from the surface of the resettling tank. 
29. Make a cross (x) on the days when sludge is removed from the reset- 
tling tank. 
30. Make a cross (x) on the days when the sides and slopes of the reset- 
tling tanks are cleaned. 
31. Settleable solids in the raw sewage (c.c. or ml. per liter after one-hour 
settling period) determined by Imhoff cone test daily. 
32. Settleable solids in Imhoff tank effluent as in 31. 
33. Settleable solids in the effluent from the filter bed as in 31. 
34. Settleable solids in the plant effluent as in 31. 
35. State the temperature (F. °) effluent of the plant. 
36. State the number of days for decolorization of methylene blue in the 
sample of the filter bed effluent at least once each week. 
37. Putrescibility of final effluent as in 36. 
38. State units of the plant by-passed and number of hours each. Also 
reason for by-passing. Use column under remarks where necessary. 
39. Use this column to more fully describe special conditions under other 
columns. Also note any unusual condition around the plant or in the 
stream used as the outlet. 
30 40. State the quantity of screenings removed each day in cubic feet or 
gallons and method of disposal. 
41. State where the sludge from the drying bed is disposed of and whether 
it is used for any useful purpose. 
42. Describe conditions in the stream into which the effluent from the 
plant is discharged, such as sludge deposits, odors, floating solids and 
growths. 
43. State how the rate of flow is determined for column 7. 
44. Give total power consumption for the plant and such additional infor- 
mation regarding power as may be desired by the municipality. 
45. Describe any operating problems which affect the efficiency of the 
plant, such as industrial wastes, storm flows, etc. 
46. Make a cross (x) on days when floating material is removed from the 
surface of the settling tank. 
47. State the number of hours clarifier mechanism is operated. 
48. State cubic feet of settled sludge removed from the settling tank during 
the day. This may be determined by timing the pump operation and 
peridoically measuring the pump discharge. 
49. State depth of scum in feet on the surface of the digestor. 
50. State the depth of the sludge in feet in the digestor. 
51. State temperature (F. °) of the water circulating in the digestor at the 
outlet of the coils. 
52. State the temperature (F. °) of the sludge in the digestor. The over- 
flow liquor may be used as an indicator. 
53. State pH value of the digesting sludge. 
54. State cubic feet of gas produced from the digesting sludge per day. 
55. State total weight of chlorine cylinders in use at the same time each 
day. 
56. State actual weight of chlorine used during preceding 24 hours. 
57. State rate of application of chlorine in pounds per 24 hours as indicated 
by the monometer or reading on the chlorinator during the day. 
58. State the rate of chlorine application as in 57 during the night. 
59. State results of residual chlorine test in parts per million made on the 
sample collected at the outlet of the contact chamber. 
60. State the time of making chlorine test 59. 
31 Appendix 1 
Simple Laboratory Methods for the Control of the 
Operation of Sewage Treatment Plants 
I. PUTRESCIBILITY (Methylene Blue Test) 
Sewage is composed of organic and inorganic substances suspended or 
dissolved in water. Generally, the strength of sewage depends on the quantity 
and state of oxidation of organic* matter present. The Biochemical Oxygen 
Demand and the Methylene Blue Putrescibility tests for sewage are based on 
the amount of oxygen utilized by the sample during the testing period. 
The oxygen required to stabilize dissolved and suspended organic matter 
in sewage is derived from oxygen dissolved in the water and also from oxygen 
combined with nitrogen in the form of nitrites and nitrates. If the available 
oxygen is not sufficient for oxidation of all the organic matter, another form 
of decomposition occurs. This secondary decomposition is known as septic 
or anaerobic decomposition. 
The Methylene Blue test involves a determination of the time necessary 
for utilization of all available oxygen in a sample, the sample being placed in 
a tightly stoppered bottle and maintained at a uniform temperature. A dye 
known as methylene blue, added to a sample as an indicator at the start of a 
test, will be decolorized when the available oxygen is used up. The time 
required for such decolorization is a measure of the strength of the sample. 
This test is not applicable in the presence of free chlorine or other germi- 
cides. 
Equipment 
/2 doz. clean glass-stoppered bottles, 6 oz. capacity. 
Yz doz. pipettes, i milliliter capacity, graduated in tenths of a milliliter. 
Yz doz. drinking glasses or water tumblers. 
Preparation of Reagent 
Methylene Blue — Dissolve 0.5 grams of the double zinc salt or commer- 
cial variety of methylene blue in distilled water, and dilute to one liter. 
Procedure 
Collect enough sewage from the effluent channel to half fill a quart bottle. 
Stopper the bottle and shake violently for three minutes and then allow the 
foam to subside. Fill a clean, six-ounce, glass-stoppered bottle with the aerated 
sewage; add 0.5 milliliters of methylene blue solution below the surface of the 
liquid in the bottle; replace the glass stopper in such a manner that no air 
bubbles remain in the bottle. 
Occasionally inorganic matter may affect the strength of the sewage. 
32 Half fill a drinking glass with water and place the sample bottle upside 
down in the glass. The sample should now be placed in a room or cabinet 
where the temperature is constant at some point between 64° F. and 720 F. 
Observe daily and record the number of days elapsing before the blue color 
disappears. If the sample does not lose its color in 10 days, the effluent may 
be considered sufficiently stable. A strong sewage will decolorize the methylene 
blue in less than 10 days and a weak sewage in more than 10 days. 
The bottles may be kept clean and free from deposits of blue color and 
iron by washing with 1:1 solution of hydrochloric or muriatic acid. They 
should then be thoroughly rinsed out with clean water. Occasional washing 
with a warm soap or soap powder solution, using a small wire and bristle brush 
followed by thorough rinsing with clean water, will remove grease from the 
bottles. 
One-half dozen bottles, which should be labeled, are sufficient for the 
determination twice each week for any one sampling point. 
II. SETTLEABLE SOLIDS 
An Imhoff cone is a large glass cone of one liter capacity or approximately 
one quart. The lower end of the cone is graduated in cubic centimeters. 
It will be necessary to have at least four such cones for a daily determi- 
nation of settleable solids, allowing one each for raw sewage, primary settling 
tank effluent, filter effluent and final effluent samples. 
The test is made by filling the Imhofi: cone to the one-liter mark, allowing 
it to stand for two hours and observing the amount of solid material deposited 
in the lower end of the cone. This procedure should be standardized and 
carried out in exactly the same way each day in order to get comparable results. 
If possible, the samples should be collected at approximately 11 a.m. or 
other time to get a representative sample, and immediately transferred to the 
cones for the test. After standing for 15 minutes, each cone should be gently 
rotated to dislodge suspended matter from the sides of the cone. 
The cones should be thoroughly cleansed daily, using a long handled 
brush and a warm soap or soap powder solution. Thorough rinsing with clean 
water should follow such cleansing. 
If there is any appreciable increase in the amount of settleable solids in 
the primary settling tank effluent or final effluent, an investigation should be 
made of the plant and unsatisfactory conditions remedied. 
III. ORTHO-TOLIDIN TEST FOR RESIDUAL CHLORINE 
Equipment 
Four clear glass bottles, 4-oz. capacity, such as are commonly used by 
druggists, fitted with glass stoppers. If rubber stoppers are used, they should 
33 be boiled for one-half hour in water containing bicarbonate of soda and then 
in plain water. One wide-moulh bottle of about one pint capacity for collecting 
sample. 
Reagents 
One liter of prepared ortho-tolidin solution, preferably the 18 per cent 
acid solution. 
Color Standards 
These are prepared from two solutions of definite concentration — copper 
sulphate and potassium dichromate. 
Standard Color Solution Equivalent to 0.5 p.p.m. Residual Chlorine 
Reagents: (a) Copper sulphate solution. Dissolve 3.0 grams of copper 
sulphate and 1 ml. of concentrated sulfuric acid in distilled water and make 
up to 100 ml. 
(b) Potassium dichromate solution. Dissolve 0.5 grams of 
potassium dichromate and 1.0 ml. of concentrated sulfuric acid in distilled 
water and make up to 1 liter. 
Place 4 ml. of copper sulphate solution and 32 ml. potassium dichromate 
solution in a graduate, dilute to 100 ml. with distilled water. This standard 
should be placed in a bottle and labeled “0.5 p.p.m. Standard.” 
Directions for Making Test 
1, Fill one of the four-ounce bottles nearly full with chlorinated sewage 
which is to be tested, taken at a place near the point of application of the 
chlorine but far enough away to provide opportunity for the chlorine to mix 
with the sewage before the sample is collected. 
2. Allow the sample to stand 15 minutes after it is collected unless such 
period of contact has already elapsed since the addition of chlorine to the 
sewage sample. 
3. Add 1 c.c. of the standard ortho-tolidin solution to the sample. 
4. Mix and allow to stand ten minutes. If the sewage is very cold, warm 
slightly by holding the bottle between the hands or by heating over a fire after 
adding the solution. Care should be taken not to heat the sewage warmer 
than room temperature or the accuracy of the test will be affected. 
5. Compare the color produced with that of the “standard” noted above. 
As the turbidity of the sewage or sewage effluent makes direct comparison 
Note: Complete information concerning laboratory determinations is contained in “Standard 
Methods for the Examination of Water and Sewage” published by the American Public 
Health Association, 450 Seventh Avenue, New York City. 
34 inaccurate, place in front of the “standard” a four-ounce bottle filled with the 
same sewage or sewage effluent but without the reagent. Also, in order to 
equalize the depth of glass and of liquid looked through, place back of the 
sample which has been treated with ortho-tolidin solution a four-ounce bottle 
of distilled water. Now place the two sets, each consisting of two bottles, side 
by side, near a window and compare the color intensity by looking through 
two bottles in each instance. 
6. If the color is lighter than that in the 0.5 p.p.m. standard, the dose of 
chlorine should be increased. Then repeat test to check results, if dose of 
chlorine is varied, allowing sufficient time for the changed chlorine dose to 
reach the sampling point. 
IV. HYDROGEN-ION CONCENTRATION 
This test is a very valuable indication of the condition of the sludge in 
an Imhoff, separate-sludge-digestion, or septic tank. It may also be used to 
determine the alkalinity or acidity of sewage or effluents. 
The digestion of sludge is affected by its alkalinity or acidity. An alkaline 
condition is desirable for satisfactory sludge digestion. Some knowledge of 
the condition of the sludge can be secured by testing it with litmus paper, 
the litmus becoming blue with an alkaline sludge and red with an acid sludge. 
However, a much better knowledge of the condition of a sludge is 
obtained by means of Hydrogen-Ion Determinations. These tests are in reality 
very simple and depend on the color produced by the addition of a small 
amount of a dye solution to the sample and comparison of the resulting color 
with color standards. These standards may be either tubes of standard color 
solutions or standard colored glass discs such as are used in certain types of 
comparators. The results of this test are expressed in numbers designated 
by the symbol pH. Neutrality or the hydrogen-ion concentration of pure dis- 
tilled water is indicated by a pH value of 7.0, any value less than 7.0 being 
considered acid and any value over 7.0 alkaline. 
It has been found that sludge digestion is most favorable with a pH 
value of from 7.2 to 7.6, and that if the pH falls to 7.0 or below, foaming 
or other unsatisfactory conditions are likely to occur. 
Complete outfits for making the tests are now available and may be 
purchased from chemical supply houses. 
A brief resume of the operating procedure for this determination—using 
standard color solutions—follows: 
The sample, if sludge, should be prepared for examination usually by 
filtering through filter paper which has been water-washed previously. The 
determination of the pH is then made of the filtered liquid, known as the 
filtrate. The sample may also be prepared for the test by diluting it with 
35 pure water having a pH value of about 7.0 preferably. Dilution, however, 
should not be over 1/15. 
One of the graduated tubes is filled with the prepared sample and 
0.5 c.c. of the indicator solution added. As the turbidity of the sample usually 
makes direct comparison inaccurate, some compensation must be made for 
this turbidity. This may be done by using some apparatus such as a wooden 
block with four vertical and two horizontal holes slightly larger than the 
diameter of the tubes. 
To compensate for the turbidity of the sample, a graduated tube of the 
same size as the standard is filled with the filtered sample to which no color 
or reagent has been added, and placed in front of the color standard tube. 
In order to equalize the depth of glass and liquid looked through, place a 
tube of distilled water back of the treated sample. 
The above apparatus is optional. Complete testing outfits are now on 
the market by which this determination can be made even simpler. In some 
of the sets, standard colored glass discs are used in place of a standard color 
solution. One indicator solution, namely, brom thymol blue, which has a 
pH range of 6.0 to 7.6 is usually sufficient for ordinary conditions. 
The filtration of the sludge sample or the addition of dilution water is 
usually necessary when a pH set is used with the tubes of ordinary size, i.e., 
those having a diameter of 1 m.m. or greater. Either of these procedures may 
introduce errors, and is also time-consuming. 
A direct-reading method in which tubes of a smaller size are used is 
frequently more desirable. This method may be carried out as follows; 
With a specially graduated pipette a sample of sludge is measured into 
a depression of the porcelain plate. The proper quantity of indicator is then 
added and the sludge and the indicator mixed by inserting the tip of the 
pipette into the bottom of the depression and drawing up and blowing out 
the mixture several times. The mixture is then drawn up into the pipette 
and its color is compared with that of the standards. These are tubes of the 
same diameter as the pipette containing the indicator in buffer solutions of 
different pH values in the range of the indicator. These standard tubes are 
mounted on a white celluloid card. 
36 Appendix II 
Operating Hazards and Safety Precautions 
in Sewage Treatment Plants 
i. GAS AND EXPLOSION HAZARDS IN SEWAGE 
TREATMENT PLANTS 
Explosions in sewage treatment plants are practically without exception 
caused by the ignition of gases or vapors mixed with air in proportions favor- 
able for rapid combustion. 
The gases or vapors responsible are derived from two main sources: 
a. Gasoline and allied products brought into the plant with the 
sewage, vaporized in screen chambers, wet wells or other enclosed 
spaces to form highly explosive mixtures with the proper propor- 
tions of vapor and air, and manufactured gas from leaky gas 
mains which may find its way into sewers and through them into 
the treatment plant. 
b. Those gases caused by the decomposition of the organic matter 
settled from the sewage. This gas, which may be generated from 
decomposing matter in sewers or sewage treatment plants, is a 
mixture of Methane (CH4) 60 to 80 per cent; Carbon Dioxide 
(C02) 20 to 30 per cent; Nitrogen (N) up to 5 per cent; Oxygen 
(O) a trace; Hydrogen (H) up to 8 per cent; and Hydrogen 
Sulphide (H2S) 0 to i/2 per cent. 
This mixture of gases, often labeled sewer gas or sewage gas, is highly 
explosive when mixed in the proportion of 8 to 18 per cent gas with air. 
The gas presents not only an explosion hazard but an asphyxiation 
hazard as well. Breathed into the lungs it may cause headache, sleepiness 
or asphyxiation. 
This gas is almost odorless unless a small amount of Hydrogen Sulphide, 
rotten egg odor, is present in the mixture of component gases. It has a heat- 
ing value of 650 to 750 B.T.U. per cubic foot and is lighter than air. (Its 
weight is % that of an equal volume of air.) 
Danger Points 
Unventilated control manholes, screen chambers and wet wells of pump- 
ing plants where turbulent flow releases gases and increases the vaporization 
cf gasoline or allied products to form explosive mixtures with the air. Dry 
wells, heater and control rooms of pumping plants and pipe galleries where 
leaks in sewage, sludge, and gas piping may cause gas accumulations from the 
37 gas generated by decomposition of organic matter in the pipe line or in the 
digester. Irnhoff tanks and separate sludge digesters where active decomposi- 
tion of organic matter is producing gas continuously. 
Precautions for Safety 
a. Always be careful. 
b. Do not go into doubtful enclosed spaces without having first tested 
for gas. If you must go in without testing, put on a safety harness 
with the attached life line in the hands of two able assistants who 
remain on the surface. Do not smoke. Keep open flame away. 
c. Remember that wherever an explosion hazard exists an asphyxia- 
tion hazard exists also. 
d. Wear rubber soled shoes and take great care in the use of tools so 
as not to cause sparks when working in dangerous places. 
e. See that all vents to enclosed spaces are clear of obstructions. 
Remove manhole covers or open wide all hatch covers to the open 
air for a reasonable period of time before entering enclosed spaces. 
f. The housing to Imhoff tanks should be well posted with “No 
Smoking” signs, one at each entrance and several inside the hous- 
ing, This unit should have ample roof ventilation. Window vents 
should be opened for additional ventilation when the operator is 
working here. 
g. Gas in separate sludge digesters and the gas piping system should 
be kept under pressure at all times. It may be desirable to add 
water or clarified sewage to the digester to maintain pressure when 
drawing ripened sludge. The digester and gas piping system 
should be examined occasionally for leaks. The water level should 
be maintained in automatic drip traps. Relief vents should never 
discharge into enclosed spaces and they should be examined fre- 
quently for clogging by frost or other material. 
h. Develop an awareness to the plant danger points for gas and explo- 
sion hazards. Do not smo\e when wording around these places. 
Keep open flames and blow torches away. Remember that an 
explosion hazard is practically always an asphyxiation hazard. Do 
not enter doubtful places when alone. As a minimum precaution 
wear a safety harness and place the life line in the hands of two' 
able helpers. Always be careful. 
38 2. SAFETY PRECAUTIONS 
A. A telephone should be available at the plant when practicable so that the 
operator, if alone, may make regular reports to a responsible person. 
B. Portable manhole guards should be used at all times where a manhole 
cover or grating has been removed. 
C. Walks, gratings, stairways and guard rails should be installed to make 
access to all units as safe as possible. 
D. A yard light should be provided for safety in night operation. 
E. Guards should be provided around all moving parts of equipment such 
as pump shafts, fly wheels, etc. 
F. Lubrication should not be performed while the equipment is in operation. 
G. Floors and walkways should be kept dry and clean to prevent slipping. 
H. Adequate washing and shower facilities should be provided. 
I. Cuts, burns, etc., should be treated immediately and carefully protected 
until healed. 
J. Direct contact of the hands with sewage or sludge should be avoided. 
K. Employees should be vaccinated against typhoid fever. 
39 APPENDIX III 
Discharge in Gallons per Minute over Right-Angled V-Notched Weir 
by Formula Q = 2.52 H2-47 
II 
In. 
H 
Ft. 
Q-gallons 
per minute 
11 
In. 
H 
Ft. 
Q-gallons 
per minute 
II 
In. 
II 
Ft. 
Q-gallors 
per minute 
o- 
A 
0.0 
.010 
4- 
Vs 
0.344 
81.06 
8- 
Vs 
0.677 
431.6 
A 
.021 
k 
.354 
87.00 
A 
.688 
449.1 
Vs 
.031 
% 
.365 
93.83 
Vs 
.698 
465.4 
Vi 
.042 
A 
.375 
100.3 
A. 
.708 
482.0 
Ys 
.052 
0.762 
Vs 
. 385 
107.0 
Ys ' 
.719 
500.7 
A 
.062 
1.177 
k 
.396 
114.8 
A 
.729 
518.1 
Vs 
,073 
1.762 
Vs 
.406 
122.0 
Vs 
.740 
537.6 
1- 
.083 
2.419 
5- 
.417 
130.4 
9- 
.750 
556.5 
Vs 
.094 
3.289 
Vs 
.427 
138.2 
A 
.760 
574.2 
A 
. 104 
4.223 
k 
.437 
146.4 
A 
.771 
595.0 
Vs 
.115 
5.413 
Vs 
.448 
155.6 
Vs 
.781 
614.2 
A 
.125 
6.650 
A 
.458 
164.4 
A 
.792 
635.8 
Ys 
. 135 
8.043 
Ys 
.469 
174.3 
Ys 
.802 
655.8 
A 
. 140 
9.759 
A 
.479 
183.6 
H 
.812 
676.2 
Vs 
. 156 
11.50 
Vs 
.490 
194.2 
Vs 
.823 
699.1 
2- 
. 167 
13.60 
6- 
.500 
204.1 
10- 
.833 
720.3 
Vs 
.177 
15.70 
Vs 
.510 
214.4 
A 
.844 
743.9 
A 
. 188 
18.22 
A 
.521 
226.0 
A 
.854 
765.9 
Vs 
. 198 
20.74 
Vs 
.531 
236.8 
Vs 
.865 
790.5 
A 
.208 
23.39 
V2 
.542 
249.2 
A 
.875 
813.2 
Ys 
.219 
26.57 
Ys 
.552 
260.7 
Vs 
.885 
836.4 
Y 
.229 
29.67 
k 
.562 
272.5 
k 
.896 
862.3 
Vs 
.240 
33.31 
Vs 
.573 
285,8 
Vs 
.906 
886.3 
3- 
.250 
36.85 
7- 
.583 
298.3 
ii- 
.917 
913.1 
Vs 
.260 
40.59 
Vs 
.594 
312.4 
Vs 
.927 
937.9 
A 
.271 
44.97 
A 
.604 
325.6 
A 
,938 
965.6 
Vs 
.281 
49.18 
Vs 
.615 
340.4 
Vs 
.948 
991.2 
V 
.292 
54.07 
A 
.625 
354.4 
A 
.958 
1017.3 
Vs 
.302 
58.76 
Ys 
.635 
368.4 
Ys 
.969 
1046.4 
A 
.312 
63.69 
A 
.046 
384.4 
A 
.979 
1073.3 
Vs 
.323 
69.38 
Vs 
.656 
399.2 
Vs 
.990 
1103.3 
4- 
.333 
74.80 
8- 
.667 
416.0 
12- 
1.000 
1131.1 
1 c. f. s. 
= 448.83 
gpm = 646,205 GPD = 
1.983 Ac. Ft. p. d. 
40 Appendix IV 
STATE WATER POLLUTION CONTROL ACT 
Laws of 1945, Chapter 395 
Chapter 395 — S. F. No. 460 
AN ACT relating to the pollution of any waters of the state and to the 
disposal of sewage, industrial waste, and other wastes, and amending Minne- 
sota Statutes 1941, Section 144.38. 
Be it enacted by the Legislature of the State of Minnesota; 
Section 1. Subdivision 1. The following words and phrases when used 
in this act, unless the context clearly indicates otherwise, shall have the mean- 
ings ascribed to them in this section. 
Subd. 2. “Sewage” means the water-carried waste products from resi- 
dences, public buildings, institutions or other buildings, including the excre- 
mentitious or other discharge from the bodies of human beings or animals, 
together with such ground water infiltration and surface water as may be 
present. 
Subd. 3. “Industrial waste” means any liquid, gaseous or solid waste 
substance resulting from any process of industry, manufacturing trade or busi- 
ness or from the development of any natural resource. 
Subd. 4. “Other wastes” means garbage, municipal refuse, decayed wood, 
sawdust, shavings, bark, lime, sand, ashes, offal, oil, tar, chemicals, and all 
other substances not sewage or industrial waste which may pollute or tend to 
pollute the waters of the state. 
Subd. 5. “Pollution” means the contamination of any waters of the state 
so as to create a nuisance or render such waters unclean, or noxious, or impure 
so as to be actually or potentially harmful or detrimental or injurious to public 
health, safety or welfare, to domestic, commercial, industrial or recreational use, 
or to livestock, wild animals, bird, fish, or other aquatic life. 
Subd. 6. “Sewer system” means pipe lines or conduits, pumping stations, 
and force mains, and all other constructions, devices, and appliances appurte- 
nant thereto, used for conducting sewage or industrial waste or other wastes 
to a point of ultimate disposal. 
Subd. 7. “Treatment work” means any plant, disposal field, lagoon, dam, 
pumping station, constructed drainage ditch or surface water intercepting ditch, 
incinerator, area devoted to sanitary land fills, or other works not specifically 
mentioned herein, installed for the purpose of treating, stabilizing or disposing 
of sewage, industrial waste, or other wastes. 
Subd. 8. “Disposal system” means a system for disposing of sewage, 
industrial waste and other wastes, and includes sewer systems and treatment 
works. 
41 Subd. 9. “Waters of the state” means all streams and lakes, including 
all rivers and lakes bordering on the state, marshes, watercourses, state, county, 
town or judicial drainage systems and other bodies of water, natural or artificial, 
public or private, of such character that the pollution thereof may create a 
nuisance or be either actually or potentially harmful or detrimental to the public 
health, safety or welfare, or to domestic, commercial, industrial or recreational 
use, or to livestock, wild animals, birds, fish, or other aquatic life. 
Subd. 10. “Person” means any municipality, governmental subdivision, 
public or private corporation, individual, partnership or other entity. 
Sec. 2. Subdivision 1. There is hereby created a water pollution control 
commission, hereinafter referred to as the commission, which shall consist of 
the secretary and executive officer of the state board of health, the commissioner 
of conservation, the commissioner of agriculture, dairy and food, the secretary 
and executive officer of the state livestock sanitary board, and a member at 
large who shall be appointed by the governor and shall hold office for four 
years and until his successor shall have been appointed and qualified. The 
member at large shall receive no compensation for his services but he shall 
receive necessary and actual traveling and subsistence expenses for any meeting 
of the commission or for trips which he may make in connection with the work 
of the commission. The other members of the commission shall receive no 
additional compensation for their services as members of the commission, but 
shall receive their necessary and actual traveling and subsistence expenses while 
engaged in the business of the commission, which shall be paid from the appro- 
priations to their several departments. 
Subd. 2. The commission shall hold quarterly regular meetings each 
calendar year at a time and place to be fixed by the commission. It shall select 
at its first meeting following the passage and approval of this act two of its 
members to serve as chairman and vice-chairman, respectively, and at the first 
regular meeting in each calendar year thereafter which shall be held in January, 
it shall select two of its members to serve for the ensuing year as chairman and 
vice-chairman, respectively. The secretary and executive officer of the state 
board of health shall serve as secretary of the commission and shall have custody 
£>f its files and records except such as are required to be filed with the secretary 
of state or otherwise. Special meetings of the commission may be called by the 
chairman or by any two other members upon at least two days’ written notice 
mailed to each other member of the commission or delivered at their respective 
offices. A majority of members of the commission shall constitute a quorum. 
Sec. 3. Subdivision 1. The commission is hereby given and charged 
with the following powers and duties: 
Subd. 2. To administer and enforce all laws relating to the pollution of 
any of the waters of the state; 
Subd. 3. To investigate the extent, character, and effect of the pollution 
of the waters of the state and to gather data and information necessary or 
desirable in the administration or enforcement of pollution laws, and to make 
such classification of the waters of the state as it may deem advisable; 
42 Subd. 4. To establish and alter such reasonable pollution standards for 
any waters of the state in relation to the public use to which they are or may be 
put as it shall deem necessary for the purposes of this act; 
Subd. 5. To make and alter reasonable orders requiring the discontinu- 
ance of the discharge of sewage, industrial waste or other wastes into any waters 
of the state resulting in pollution in excess of the applicable pollution standard 
established under Subdivision 4 of this section; 
Subd. 6. To require to be submitted and to approve plans for disposal 
systems or any part thereof and to inspect the construction thereof for compli- 
ance with the approved plans thereof; 
Subd. 7. To issue, continue in effect or deny permits, under such con- 
ditions as it may prescribe for the prevention of pollution, for the discharge of 
sewage, industrial waste or other wastes, or for the installation or operation 
of disposal systems or parts thereof; 
Subd. 8. To revoke or modify any permit issued under this act whenever 
it is necessary, in the opinion of the commission, to prevent or abate pollution 
of any waters of the state; 
Subd. 9. To prescribe and alter rules and regulations, not inconsistent 
with law, for the conduct of the commission and other matters within the scope 
of the powers granted to and imposed upon it by this act, provided that every 
rule or regulation affecting any other department or agency of the state, or 
any person other than a member or employee of the commission shall be filed 
with the secretary of state; and 
Subd. 10. (1) To conduct such investigations and hold such hearings 
as it may deem advisable and necessary for the discharge of its duties under 
this act, and to authorize any member, employee or agent appointed by it to 
conduct such investigations or hold such hearings. 
(2) In any such hearing or investigation, any member of the commission, 
or any employee or agent thereto authorized by the commission, may administer 
oaths, examine witnesses and issue, in the name of the commission, subpoenas 
requiring the attendance and testimony of witnesses and the production of 
evidence relevant to any matter involved in any such hearing or investigation. 
Witnesses shall receive the same fees and mileage as in civil actions. 
(3) In case of contumacy or refusal to obey a subpoena issued under this 
section, the district court of the county where the proceeding is pending or in 
which the person guilty of such contumacy or refusal to obey is found or resides, 
shall have jurisdiction upon application of the commission or its authorized 
member, employee or agent to issue to such person an order requiring him to 
appear and testify or produce evidence, as the case may require, and any failure 
to obey such order of the court may be punished by said court as a contempt 
thereof. 
Sec. 4. Subdivision 1. Any person operating a disposal system, when 
requested by the commission, shall furnish to it any information which he may 
have which is relevant to the subject of this act. 
43 Subd. 2. The commission or any employee or agent thereof, when author- 
ized hy it, may examine any hooks, papers, records or memoranda pertaining 
to the operation of a disposal system. 
Subd. 3. Whenever it shall be necessary for the purposes of this act, the 
commission or any member, employee or agent thereof, when authorized by 
it, may enter upon any property, public or private, for the purpose of obtaining 
information or conducting surveys or investigations. 
Sec. 5. Subdivision 1. No final order of the commission shall be effec- 
tive as to the vested rights of any person adversely affected thereby nor as to 
any disposal system operated by any person unless the commision or its author- 
ized officer, member, or agent shall have held a hearing upon the matter 
therein involved at which evidence may be taken, of which hearing such 
person shall have had notice as hereinafter provided. Any person who will 
be directly affected by the final order therein shall have the right to be heard 
at the hearing and to submit evidence thereat. Written notice specifying the 
time and place of the hearing shall be served by the commission upon all 
persons known by it to be directly affected by the final order, personally or 
by registered mail not less than ten days before the date of the hearing. A 
copy of the final order shall be served in the same manner upon all persons 
who entered an appearance at the hearing. 
Subd. 2. Notwithstanding the provisions of Subdivision 1 of this section, 
the commission, when it shall have first determined that an emergency exists 
respecting any matter affecting the public health, may make a final order 
without notice and without a hearing. A copy of such final order shall be 
served as provided in Subdivision 1 of this section. 
Subd. 3. An appeal may be taken from any final order, rule, regulation, 
or other final decision of the commission by any person who is or may be 
adversely affected thereby, or by the attorney general in behalf of the state, 
to the district court of Ramsey County in the manner herein provided. Within 
30 days after receipt of a copy of the order, rule, regulation, or decision, or 
after service of notice thereof by registered mail, but not in any case more 
than six months after the making and filing of the order, rule, regulation or 
decision, the appellant or his attorney shall serve a notice of appeal on the 
commission, through its secretary; provided, that during such 30 day period 
the court may, for good cause shown, extend such time for not exceeding an 
additional 60 days, but not beyond the expiration of such six months’ period. 
The notice of appeal shall refer to the action of the commission appealed from, 
shall specify the grounds of the appeal, including points of both law and fact 
which are asserted or questioned by the appellant, and may contain any other 
allegations or denials of fact pertinent to the appeal. The notice shall state 
an address within the state at which service of notice and other papers in the 
matter may be made upon the appellant. The original notice of appeal, with 
proof of service, shall be filed by the appellant or his attorney with the clerk 
of the court within ten days after the service of the notice, and thereupon the 
court shall have jurisdiction of the appeal. 
44 Subd. 4. The appellant and the commission shall in all cases be deemed 
the original parties to an appeal. The state, through the attorney general, or 
any other person affected may become a party by intervention as in a civil 
action, upon showing cause therefor. The attorney general shall represent the 
commission, if requested, upon all such appeals unless he appeals or inter- 
venes in behalf of the state. No bond or deposit for costs shall be required of 
the state or the commission upon any such appeal or upon any subsequent 
appeal to the supreme court or other court proceedings pertaining to the matter. 
Subd. 5. The venue of an appeal may be changed by order of the court 
upon written consent of the parties or for cause shown, after hearing upon 
notice to all parties, as in a civil action, to the district court of any county in 
which the order, rule, regulation, or decision appealed from would take effect. 
Subd. 6. Within 30 days after service and filing of the notice of appeal 
the commission, through its secretary, shall make, certify, and file with the 
clerk of the court having jurisdiction of the appeal a return comprising a copy 
of any application, petition, or other material paper whereon the action of the 
commission appealed from was based, a copy of the order, rule, regulation, 
or decision appealed from, a statement of any finding of fact or ruling or 
conclusion of law made by the commission in the matter, and such other state- 
ments, admissions, or denials upon questions of law or fact raised by the appeal 
as the commission may deem pertinent. Such 30 day period may be extended 
by the court for cause shown for not exceeding an additional 60 days. Within 
the time allowed for making and filing the return a copy thereof shall be 
mailed to or served upon the appellant or his attorney. The allegations of new 
matter in the return shall be deemed to be denied by the appellant unless 
expressly admitted, and no further pleadings shall be interposed. Otherwise 
the allegations of the notice of appeal and return shall have like effect as the 
pleadings in a civil action and shall be subject to like proceedings, so far as 
applicable. 
Subd. 7. The appeal shall be heard and determined by the court upon 
the issues raised by the notice of appeal and return according to the rules 
relating to the trial of civil actions, so far as applicable. The court of its own 
motion or on application of any party may, in its discretion, take additional 
evidence on any issue of fact or may try any or all such issues de novo, but 
no jury trial shall be had. If the court shall determine that the action of the 
commission appealed from is lawful and reasonable, and is warranted by the 
evidence in case an issue of fact is involved, the action shall be affirmed. Other- 
wise the court may vacate or suspend the action appealed from in whole or in 
part, as the case may require, and thereupon the matter shall be remanded to 
the commission for further action in conformity with the decision of the court. 
Subd. 8. The taking effect of any action of the commission shall not be 
stayed by an appeal except by order of the court for cause shown by the 
appellant. The granting of a stay may be conditioned upon the furnishing 
by the appellant of such reasonable security for costs as the court may direct. 
A stay may be vacated on application of the commission or any other party 
45 after hearing upon notice to the appellant and to such other parties as the 
court may direct. 
Subd. 9. In any appeal or other proceeding involving any order, rule, 
regulation, or other decision of the commission, the action of the commission 
shall be prima facie reasonable and valid, and it shall be presumed that all 
requirements of the law pertaining to the taking thereof have been complied 
with. All findings of fact made by the commission shall be prima facie 
evidence of the matters therein stated. The burden of proving the contrary 
of any provision of this subdivision shall rest upon the appellant or other party 
questioning the action of the commission. 
Subd. 10. If no appeal be taken from an order, rule, regulation, or other 
decision of the commission as herein provided, or if the action of the commis- 
sion be affirmed on appeal the action of the commission in the matter shall be 
deemed conclusive, and the validity and reasonableness thereof shall not be 
questioned in any other action or proceeding, but this shall not preclude the 
authority of the commission to modify or rescind its actions. 
Sec. 6. Subdivision 1. The commission, so far as it is not inconsistent 
with its duties under the laws of this state, may assist and cooperate with any 
agency of another state, of the United States of America or of the Dominion 
of Canada or any province thereof in any matter relating to water pollution 
control. 
Subd. 2. The commission may receive and accept money, property, or 
services from any person or from any agency described in Subdivision 1 or 
from any other source for any water pollution control purpose within the scope 
of its functions under this act, and all moneys so received are hereby appro- 
priated for such purposes in like manner and subject to like provisions of law 
as the corresponding appropriations of state funds. 
Sec. 7. This act shall not be construed as repealing any of the provisions 
of law relating to the pollution of any waters of the state, but shall be held 
and construed as supplementing the same and in addition to the laws now 
inforce, except as the same may be in direct conflict herewith. 
Sec. 8. Subdivision 1. It shall be unlawful for any person to construct, 
install or operate a disposal system, or any part thereof, until plans therefor 
shall have been submitted to the commission unless the commission shall have 
waived the submission thereof to it and a written permit therefor shall have 
been granted by the commission. 
Subd. 2. It shall be unlawful for any person to make any change in, 
addition to or extension of any existing disposal system or part thereof that 
would materially alter the method or the effect of treating or disposing of 
the sewage, industrial waste or other wastes, or to operate such system, or 
part thereof as so changed, added to, or extended until plans therefor shall 
have been submitted to the commission unless the commission shall have 
waived the submission thereof to it and a written permit therefor shall have 
been granted by the commission. 
46 Subd. 3. Violation of any provision of this act or of any regulation 
adopted by the commission thereunder shall be a misdemeanor. 
Subd. 4. Pollution of any waters in violation of any provisions of this 
act, or of any order or regulation adopted by the commission thereunder shall 
constitute a public nuisance, and may be enjoined and abated as such as 
provided by law. 
Sec. 9. The commission, upon application of the appropriate person, 
shall issue a permit for the continuance of every disposal system now operating 
pursuant to proper legal authority subject, however, to the right of the com- 
mission to modify or revoke such permit in the same manner as other permits. 
Sec. 10. Every person who claims damages from the holder of a permit 
issued hereunder for the operation of a disposal system or from any employee 
or agent of such permit holder for or on account of any loss or injury sustained 
by reason of the operation of such system in respect of the treatment or disposal 
of sewage, industrial waste, or other wastes therein, or by reason of the dis- 
charge of any effluent therefrom, shall cause to be presented to such permit 
holder and to the secretary of the commission within 30 days after the alleged 
loss or injury occurred a written notice, stating the time, place, and circum- 
stances thereof, and the amount of compensation or other relief demanded. 
No action therefor shall be maintained unless such notice has been given, or 
if commenced within ten days thereafter or more than one year after the 
occurrence of the loss or injury. 
Sec. 11. This act may be cited as the State Water Pollution Control Act. 
Sec. 12. Minnesota Statutes 1941, Section 144.38, is amended to read as 
follows: 
“144.38. Subdivision 1. The board is hereby given and charged with 
the power and duty of administering and enforcing all laws relating to the 
pollution of any of the waters of this state, so far as such pollution affects the 
public health. 
Subd. 2. The board shall make such investigations of water pollution 
and the plans for the construction of works affecting water pollution as may 
be required by the water pollution control commission. The board shall fur- 
nish to such commission such other services as the commission may need in 
the administration of the State Water Pollution Control Act, including the 
employment of a qualified and experienced sanitary engineer, who shall be 
designated by the board, with the approval of the commission, to act as con- 
sultant to the commission. 
Subd. 3. The board is hereby specifically authorized to cooperate with 
other departments of state, other state officers, with municipalities of all kinds, 
with other states, the United States, the Dominion of Canada or any province 
thereof, industries, societies, corporations, and individuals, to the end and 
purpose of protecting and freeing the waters of the state from pollution.” 
47 
4-19-45 Location 
Drainage Basin 
(River) 
Year Const, of 
Municipal San. 
Sewer System 
Commenced 
Year 
S. T. P. 
Constructed 
Pop. 
(1940) 
Treatment Units 
Final Disposal 
1896 
1913 
1,988 
1,066 
975 
Septic tank 
Marsh River 
1920 
1920 
I, SI. B 
Kanavanzie River 
1922 
1921 
I, SI. B 
Two Rivers 
A.llDPT't T 0ft 
1910 
1927 
12,200 
5,051 
I, SI. B 
Albert Lea Lake 
Upper Mississippi 
1912 
1929 
I, T. F., F. S., SI. B 
Lake Winona 
1922 
1922 
576 
I, SI. B 
Blue Earth River 
A i 
1921 
1922 
755 
I, SI. B 
Pleasant Lake 
Anoka 
1917 
1917 
6,426 
1, SI. B 
Mississippi River 
1934 
1,877 
I, T. F., F. S., SI. B 
Pomme de Terre River 
1928 
1928 
1,122 
1,528 
I, SI. B 
High Island Creek 
1936 
1940 
I, T. F., F. S., SI. B 
Creek to St. Louis River 
1892 
1924-39 
18,037 
Grease Fit., Floe., P. S., 
1939 
1940 
1,241 
H. T. F., Int. S., T. F., 
F. S., CL, D., SI., B.. . . 
P. S., T. F., F. S., CL, D., 
Cedar River 
SI. B 
1909 
1988 
1,450 
P.8., A.S., F.S., CL, SI. B. 
Willow Creek 
1909 
1909 
1,017 
2,633 
Septic tank 
Baudette River 
After 1920 
1940 
P.S., A.S., F.S., CL, D., 
SI. B 
St. Croix River 
1906 
1934 
9,427 
Grit, Com., P.S., T.F., 
1897 
1936 
2,729 
F.S., CL, D., Si. B 
P.S., T.F., F.S., D., CL, 
Mississippi River 
SI B 
Chippewa River 
Creek east of Village 
1937 
1937 
578 
I, T.F., F.S., CL, SI. B.. . 
1913 
1913 
753 
1, SI. B 
Black Duck Lake 
1918 
1915-33 
1,205 
P.S., T.F., D., SI. B 
Ditch to West Fork 
R11 ip 
1934 
1934 
125 
I., T.F., F.S., SI. B 
Bogus Creek 
1910 (About) 
1941 
1934 
1,355 
I., SI. B 
Trout Lake 
1940 
578 
P.S., T.F., F.S., D., CL, 
1919 
1940 
12,071 
SI. B 
Com., P.8., T.F., F.S., CL, 
Ditch 
D., SI. B 
Mississippi River 
Minnesota River 
■pjjValley 
1914 
1923 
1,075 
1,695 
I., SI. B 
1926 
1939 
P.S., T.F., F.S., CL, D., 
SI. B 
Rnhl 
1926 
1,600 
A.S., F.S., SI. I 
Creek 
Butterfield 
Blue Earth 
1918 
1928 
511 
L, si. B 
N. B. Watonwan River 
Appendix V 
MINNESOTA DEPARTMENT OF HEALTH 
Division of Water Pollution Control 
Municipalities Having Sewer Systems With Sewage Treatment Plants 
January 1, 1947 
48  
1917 
1917-37 
1,985 
294 
1., T.F., F.S., Cl., SI. B.. . 
1., SI. B 
Dry run 
County ditch 
1936 
1938 
1910 
1922 
946 
i.; SI. B 
1909 
1910 
2,099 
Lac Qui Parle River 
1941 
1,640 
492 
P.S., H. T.F., F.S., CL, SI. 
Chem 
I., T.F., F.S., SI. B 
1937 
1940 
Root River (North fork) 
Drainage Ditch 
1936 
1937 
845 
1., T.F., F.S., CL, SI. B. 
1., SI. B 
1916 
1916 
398 
1936 
1938 
965 
I., T.F., F.S., SI. B 
1936 
1937 
630 
i.; SI. B.. . . 
Dry run 
1907 
1942 
1,175 
1,325 
6,035 
470 
P.S., H. T.F., F.S., CL, SI. 
Chem. 
1910 (About) 
1927 
1920 (Before) 
1938 
Mississippi River 
Little Fork River 
Cook 
1938 
1940 
I., SI. B ~ 
1939 
1940 
690 
GritP.S., H.T.F., F.S..CL, 
D., SI. B 
1919 
2,954 
357 
Cottonwood Lake 
1936 
1936 
I., SI. B 
Chippewa River 
Ditch to Lac Qui Parle R. 
Cranberry Lake 
1917 
1917 
1,664 
570 
I., 81. B 
1914 
1917 
I., SI. B 
1919 
1929-41 
5,015 
1,068 
1,029 
101,065 
815 
(I., T.F., F.S., Old P.) F. 
Screens, H.T.F., Int. S., 
T.F., F.S., CL, V.F., SI. 
Chem. SI. B 
Moorhead sewer system . . 
I , SI. B.. , 
1936 
1935 
Creek to St. Clair Lake 
Red River of North 
Zumbro River 
1917 
1917 
1883 
1940 
Grit, Floe., P.S., D„ CL, 
V.F., Inc 
I., T F., F.S., SI. B 
1921 
1939 
Lake Superior 
1923 
1938 
5,855 
1,150 
5,970 
334 
Mississippi River 
1926 
1926 
Ely 
1901 
1912 
I., SI. B 
Shagawa Lake 
1923 
1923 
I.j SI. B 
1900 
1914-20 
6,887 
1,422 
.1,116 
6,988 
1,580 
10,848 
961 
I., T.F., F.S., SI. B 
Creek to Elbow Lake 
About 1927 
1939 
Com. P.S , T.F., F.S., S.F., 
1940 
D., CL, SI. B„ Glass 
Covered 
P.8., T.F., F.S., CL, D., 
SI. B 
1., T.F., F.S., CL, D., SI. B. 
1., SL, B 
Lake Minnetonka 
1907 
1918-30-34 
Creek to Minnesota River 
1917 
1917 
1936 
Grit P.S., D„ CL, SL B.. . 
I., SL B 
1919 
1921 
Stony Brook 
1919 
1941 
1,120 
1,271 
515 
Com., P.S., P. & Sec., A.S., 
F.S., CL, D., SL B 
I., T.F., F.S., SL B 
1915 
U. C. 
Clear Lake 
Poplar River 
1923 
1936 
I., T.F., F.S., SL B 
1923 
1936 
I. T.F., F.S., SL B... 
155 
I., SL B. . 
(P. 0. Chisholm) 
1941 
1946 
1,167 
548 
I., SI. B 
1920 
1930 
I., 81. B 
Fulda 
Des Moines 
About 1910 
1937 
984 
i.; SI. B 
County Drain Tile Location 
Drainage Basin 
(River) 
Year Const, of 
Municipal San. 
Sewer System 
Commenced 
Year 
S. T. P. 
Constructed 
Pop. 
(1940) 
Treatment Units 
Final Disposal 
1916 
1916 
1,049 
761 
I., SI. B 
1935 
1936 
P.'S., D., SI. B. 
County Ditch to Rush River 
1912 
1915 
2,504 
2,387 
2,564 
480 
I., T.F., F.S., SI. B 
1915 
1934 
I., A.S., F.S., Cl., SI. B.. . 
1904 
1933 
I., T.F., F.S., 81. B 
1940 
1940 
P.S.,T.F.,F.S., Cl., D.S1.B. 
I., SI. B 
1907 (About) 
1933 
1922 
1,020 
855 
1940 
I.’ CL, SI. B 
Lake Superior 
1919 
1939 
700 
I., H.T.F., F.S., CL, SI. B. 
Granite Falls 
Minnesota 
1906 
1935 
2,388 
P.’S., D., T.F., F.S., CL, 
SI. B 
Minnesota River 
1923 
1922 
447 
I., SI. B 
1910 (About) 
1919 
1904 
1,353 
827 
1937 
I., T.F., F.S., CL, SI. B... 
Ditch east of village 
1923 
1928 
890 
I., SI. B 
1917 
1919 
740 
i.; si. b 
Henning 
Upper Mississippi 
1938 
1940 
948 
P.'S., T.F., F.S., CL, D., 
SI. B 
Ditch to Willow River 
Hibbing 
St. Louis 
1900 
1940 
16,385 
Com., Floe., P.S., T.F., 
F.S., D., SI. B 
Hibbing Creek 
1916 
1917 
4,100 
977 
L, SI. B 
1936 
1937 
Com., I., CL, SI. B.. . . 
Hutchinson 
Crow 
1902 
1934 
3,887 
P.S., T.F., F.S., D., SI. B. 
Crow River 
1916 
1917 
827 
I., SI. B 
1935 
1937 
567 
P.'S., D., SI. B 
Swamp to Knife River 
1916 
1920 
1,296 
1,422 
I., SI. B 
Jordan 
Minnesota 
1919 
1926 
i.; si. b 
Sand Creek 
Kasson 
Zumbro 
1913 
1913-41 
1,230 
2 I., T.F., F.S., SI. B 
Creek to Zumbro River 
Keewatin 
Upper Mississippi 
1914 (About) 
1942 
1,942 
Grit, I., T.F., F.S., CL, 
SI. B 
O’Brien Creek 
1914 
1914 
357 
I., SI. B 
1909 
1924 
1,530 
462 
I., SI. B 
Kinney 
St. Louis 
1920 
1920 
L, SI. B 
Creek to McQuade River 
La Crescent 
Mississippi 
1939 
1940 
815 
P.S., T.F., F.S., CL, D„ 
SI. B 
Mississippi River 
1920 
1920 
961 
I., SI. B 
Lake City 
Lower Mississippi 
1921 
1934 
3,204 
P.S., D„ CL, F.S., SI. B. 
Mississippi River 
Appendix V—Continued 
MINNESOTA DEPARTMENT OF HEALTH 
Division of Water Pollution Control 
Municipalities Having Sewer Systems With Sewage Treatment Plants 
January 1, 1947 
50  
1916 
1915 
1,319 
1,699 
I., SI. B 
Lily Lake 
1914 
1940 
F.' Screen, P.H.T.F., I., 
1920 
1939 
S., Sec. H.T.F., SI. 
Chem., F.S., Cl 
1., T.F., F.S., CL, SI. B.. . 
1., TF., F.S., SI. B 
Ditch to Heron Lake 
1923 
1935 
Dry Run to Vermillion R. 
No. Branch of Two Rivers 
1919 
1920 
475 
I., SI. B 
1923 
1939 
1,100 
P.'S., T.F., F.S., CL, D., 
1924 
1924 
1,232 
440 
SI. B 
I., SI. B 
Root River 
County Ditch 
Creek to St. Louis River 
I., SI. B 
After 1915 
1937 
761 
P.S., T.F., F.S., CL, D„ 
SI. B 
Com., P.S., T.F., F.S., 
CL, D., SI. B 
I., SI. B. * 
1912 
1927 
5,920 
Dry Run 
1935 
1939 
608 
Jewett Creek 
Little Fork River 
1910 
1942 
2,311 
Com., P.S., H.T.F., F.S., 
1939 
1940 
903 
CL, SI. Chem 
1., T.F., F.S., CL, SI. B.. . 
1., SI. B 
Long Prairie River 
Poplar River 
Lake to Embarrass R. 
McKinley 
St. Louis 
1920 
1918 
235 
1916 
1916-39 
741 
I., H.T.F., F.S., CL, SI. B. 
Creek to South fork of Root R. 
1916 
1916 - 
2,312 
I., SI. B 
Ditch to Lac Qui Parle R. 
Ramsey Lake 
1914 
1922 
637 
I., SI. B 
1915 
1915 
1,070 
I., SI. B 
1911 
1936 
792 
i.; 81. B 
Marshall 
Minnesota 
1904 
1931 
4,590 
I., T.F., F.S., Cl., SI. B... 
Redwood River 
1936 
142 
Minneapolis 
Upper Mississippi 
1872 
1938 
492,370 
Mpls.-St. Paul San. Dist.. 
Mississippi River 
Mpls.-St. Paul San. 
District 
Upper Mississippi 
1938 
1938 
1934 
5,220 
Grit, Floe., P.S., Mag.F., 
CL, V.F., Inc 
Grit. P.S., T.F., F.S., D., 
SI. B. 
I., SI. B 
Mississippi River 
Chippewa River 
Ditch to Lake Pepin 
1926 
1927 
1,741 
1896 
1935 
9,491 
P.’S., T.F., F.S., D., CL, 
SI. B 
P.S., D., CL, SI. B 
1919 
1939 
1,432 
1,494 
1,282 
3,214 
904 
Red River of North 
1916 
1940 
P.S.; D., SI. B„ Cl 
Morningside 
Upper Mississippi 
1926 
1907 
1938 
1928 
Mpls. sewer system 
I., SI. B 
Mississippi River 
Pomme de Terre R. 
1937 
1939 
P.S., T.F., F.S., D„ CL, 
SI. B 
I., SI. B 
1920 
1920 
1,492 
1,745 
1,645 
863 
Minnesota 
1916 
1916 
i.; SI. B 
1923 
1921 
I., SI. B 
Creek to Sand Creek 
1939 
1940 
Com., P.S., T.F., F.-S., 
1896 
1940 
8,743 
771 
CL, SI. B. D 
P.S., H.T.F., F.S., Mag.,F. 
CL, D., SI. B 
1., T.,F., F.S., SI. B 
Creek 
1935 
1937 
Minnesota River 
1915 
1914 
342 
I., SI. B 
1927 
1927 
3,135 
648 
I., A.S., F.S., CL, SI. B.. . 
Ditch to Kohlman’s L. 
1921 
1927 
F.' Screen, A.S., F.S., D., 
SI. B. '....' 
Ditch to Veven’s Creek 
*Imhoff Tank not completed. 
51 Location 
Drainage Basin 
(River) 
Year Const, of 
Municipal San. 
Sewer System 
Commenced 
Year 
S. T. P. 
Constructed 
Pop. 
(1940) 
Treatment Units 
Final Disposal 
1930 
1930 
1,788 
I., SI. B 
Ditch No. 61 to Minnesota R. 
1912 
1934 
2,469 
P.S., D., A.S., F.S., SI. B. 
Minnesota River 
Osakis 
Sauk 
1918 
1934-37 
1,483 
P.S., T.F., F.S., D„ CL, 
SI. B 
Osakis Lake 
Owatonna 
Cannon 
1916 
1940 
8,694 
P.S., P.H.T.F., Int.S., Sec. 
H.T.F., F.S., Cl., D., 
SI. B 
Straight River 
1938 
1940 
781 
I., T.F., F.S., Cl., SI. B.. . 
P.S., D., CL, SI. B 
Lake Adley 
1914 
1930 
2,643 
Fish Hook River 
1925 
1925 
1,317 
I., si. B 
Crow River 
1924 
1936 
1,560 
I., T.F., F.S., SI. B 
Pelican River 
Perham 
Ottertail 
1927 
1936 
1,534 
P.S., T.F., F.S., CL, D., 
SI. B 
Ottertail River 
1937 
1,718 
P.S., D., CL, SI. B 
Snake River 
Big Sioux 
Lower Mississippi 
1906 
1919-27 
4,682 
I., T.F., F.S., SI. B 
Creek 
Plainview 
1924 
1941 
1,500 
Grit, Com., Floe., P.S., 
P.H.T.F., Int.S., Sec. 
H.T.F., F.S., D., SI. B. 
Dry Run to Whitewater River 
1922 
1930 
1,865 
I., SI. B 
Rum River 
1911 
1940 
2,468 
Duluth sewer system 
Lake Superior 
1917 
1940 
1,530 
3,270 
1,265 
141 
I., CL, SI. B 
Clearwater River 
1887 
1934 
I., T.F., F.S., SI. B 
Redwood River 
Renville 
Minnesota 
1936 
1936 
P.S., H.T.F., F.S., D., 
SI. B 
P.S., SI. B 
County Ditch 
Creek to Lake 
1939 
1938 
6,018 . 
Mols. sewer system 
Mississippi River 
Rochester 
Zumbro 
Before 1904 
1926-30 
26,312 
P.S., F. Screen, A.S., F.S., 
D., SI. B 
Zumbro River 
1922 
1939 
1,775 
261 
Com., L, SI. B 
Roseau River 
1937 
1937 
I., CL, SI. B 
Rose Creek 
1920 
1926 
1,020 
I., SI. B 
Rush Creek 
Rushford 
Root 
1902 
1940 
1,182 
Com., P.S., T.F., F.S., 
CL, D., SI. B 
Root River 
1940 
1941 
752 
L, T.F., F.S., CL, SI. B.. . 
Ditch to Minnesota R. 
1922 
1922 
1,507 
I., SI. B 
Creek 
1898 
1936 
3,400 
P.S., T.F., D„ F.S., SI. B. 
Creek to North Fork 
St. Louis Park 
Mississippi 
1930 
1938 
7,737 
Mpls. sewer system 
Mississippi River 
Appendix V—Continued 
MINNESOTA DEPARTMENT OF HEALTH 
Division of Water Pollution Control 
Municipalities Having Sewer Systems With Sewage Treatment Plants 
January 1, 1947 
52  
1872 
1938 
287,756 
Mpls.-St. Paul San. Dist. 
I., T.F., F.S., SI. B 
Mississippi River 
1901 
1934 
3,016 
222 
1939 
I.. T.F., F.S. SI. B 
Creek to Minn. River 
1941 
1941 
460 
I., 81. B 
1906 
1917 
1,030 
i.; SI. B 
County Ditch to Creek to Tuttle 
Lake 
Beaver Creek 
1902 
1931 
1,587 
2,923 
11,844 
I., SI. B 
1914 
1914 
I., SI. B 
Sleepy Eye Creek 
1919 
1940 
Com., Grit, Grease Fit., 
Floe., P.S., T.F., F.S., 
Mississippi River 
1914 
1939 
2,361 
Com., P.S., T.F., F.S., Cl., 
D., SI. B 
1930 
1930 
967 
I., SI. B 
1917 
1938 
2,133 
2,952 
972 
P.S., T.F., F.S., CL. SI. B. 
I., T.F., F.S., SI. B 
Spring Valley Creek 
Hayden Creek 
Creek through Lake to Chippewa 
River 
Tamarac River 
1908 (About) 
1929 
1917-32 
1929 
i.; SI. B 
1920 
1941 
673 
I., SI. B 
1939 
1940 
1,025 
P.S., T.F., F.S., CL. D., 
SI. B 
1918 
1919 
375 
I., SI. B 
Ditch to Swan River 
After 1923 
1941 
552 
P.S., T.F., F.S., CL, D., 
SI. B 
St. Croix River 
1908 
1939 
6,019 
Com., P.S., T.F., F.S., CL, 
D., SI. B 
1937 
1937 
820 
I., SI. B 
East Branch of Two R. 
1909 
1923-38 
3,085 
12,264 
2,368 
604 
I., T.F., F.S., SI. B 
Creek to Cottonwood R. 
1914 
I., T.F., F.S., SI. B 
Three Mile Lake 
1916 
1934 
P.S., F.S., D., SI. B 
Mississippi River 
Ditch Northeast of village 
1920 
1920 
I., SI. B 
1924 
1924 
1,315 
2,916 
1,427 
939 
1., T.F., F.S., CL, SI. B... 
1., T.F., F.8., SI. B 
Waconia Lake 
1912 
1916-33 
Union Creek 
1926 
1928 
i.; CL, 81. B.. 
Walker 
1935 
1936 
P.S., T.F., CL, SI. B., D.. 
I., SI. B 
Leech Lake 
1919 
1919 
753 
County Ditch to Creek to Cot- 
tonwood River 
1908 
1914 
1,639 
1,309 
737 
I., SI. B 
1914 
1937 
I., CL, SI. B 
1934 
I., SI. B 
Crow River 
1926 
1926 
458 
I., CL, SI. B 
Lake Waverly 
1939 
1940 
1,473 
Com., P.S., T.F., F.S., 
S.F., CL, SI. B„ Glass 
Wells 
1899 
1920 
2,217 
871 
I., SI. B...' 
Ditch to Maple River 
Ditch to Highwater Creek 
Creek to Zumbro River 
1922 
1922 
i.; si. b 
1926 
1927 
744 
P.’S., A.S., F.S., D., SI. B. 
St. Paul sewer system.. .. 
F. Screen, A.S., F.S., D., 
SI. B 
1921 
1938 
5,733 
2,858 
Mississippi River 
1926 
1927 
1912 
1931 
7,623 
22,490 
222 
P.S., T.F., F.S., D., SI. B. 
P.S., CL, D., SI. B 
Ditch to South Fork of Crow R. 
1892 
1935 
1918 
1917 
I., si. B.'. . . 
W orthington 
Des Moines 
1905 
1916-32 
5,918 
P.S., T.F., F.S., D.. SI. B. 
County Ditch 
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54 Appendix VI 
References 
More detailed information on the care and operation of sewage treatment 
plants may be obtained from the following publications. 
A. Books 
“Standard Methods of Water and Sewage Analysis,” American Public 
Health Association 
“Sewage Treatment,” Imhoff and Fair 
“Sewerage and Sewage Treatment,” Hardenbergh 
“Sewage Treatment Works,” Kiefer 
“Sewerage and Sewage Treatment,” Babbit 
B. Magazines and Bulletins 
Manual of Practice No. i, “Occupational Hazards in Operation of Sewage 
Works,” Federation of Sewage Works Association 
Manual of Practice No. 2, “Utilization of Sewage Sludge as Fertilizer,” 
Federation of Sewage Works Association 
“Sewage Works Engineering,” 24 West 40th Street, New York 18, N. Y. 
“Sewage Works Journal,” Federation of Sewage Works Association, 325 
Illinois Building, Champaign, Illinois 
“Water Works and Sewerage,” Gillet Publishing Company, 330 South 
Wells Street, Chicago, Illinois 
“Public Works,” 310 East 45th Street, New York, N. Y. 
55