Papers Prepared in the Division of
Water Supply and Pollution Control, Region V
For Presentation at
ASCE WATER RESOURCES ENGINEERING CONFERENCE
Title of Paper Author
Great Lakes-Illinois River
Basins Project . t , Hf W. Poston
Project Management Planning in
PHS-REGION Water Resource Development .....,., R, D. Vaughan
V -
Combined Sewer Overflows Carlysle Pemberton
Lake Michigan Current Studies ...... W. Q, Kehr
May 1963
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GREAT LAKES-ILLINOIS RIVER BASINS PROJECT*
GOALS AND THE GREAT LAKES
by
H. W. POSTON**
In the field of Water Resources it is the task of the
Engineer, in close coordination with a vide variety of
scientific competencies, to develop plans for our water
supply of the future. This is true vhether the vater be
for public or industrial supply, propagation «f fish
and aquatic life and wildlife, recreational purposes,
agricultural or other legitimate uees. The quantity ajjd
particularly the quality of our future supply is receiving
increased attention from the Federal government.
Hundreds of bills concerning the water resource a»e
pending in State legislatures around the country and a
host of bills and legislative amendments have been
introduced in the Congress. The Congressional subjects
run from Water Resources Research, major amendments t«
the Federal Water Pollution Control Act, bills dealing
*Presented at the American Society of Civil Engineers'Wfctar
Resources Engineering Conference, Milwaukee, Wisconsin,
May 13-1T, 1963.
**Regional Program director, Water Supply and Pollution
Control, Public Health Service, Region V, U- S. Department
of Health, Education, and Welfare, Chicago, Illinois.
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with loan programs to small "businesses and Industry"for
Water Pollution Control projects; a companion till dealing
with favorable tax depreciation allowances to industry for
Water Pollution Control projects to bills covering pesticides
and their control, not to mention the bill curbing use or sale
of non-degradable detergents. These are symptomatic of many
similar measures being introduced in the State legislatures.
The politician has recognized the importance of our most
valuable resource - water.
Many of our communities in this area have been or
presently are confronted with problems of future water supply
and will continue to encounter them.
Green Bay, Wisconsin developed a new Public Water
Supply Source some 25 miles distant in Lake Michigan rather
than utilize either the Fox River or Green Bay, both close
at hand. Water quality was the deciding factor for develop-
ment of the remote supply. Detroit, Michigan, even now,
plans a Lake Huron water intake about 50 miles from its
present one at the mouth of the Detroit River. Here again
water quality is a major consideration. The State of
Illinois and the Chicago Sanitary District are presently
being heard by the U. S. Supreme Court's Special Master
to determine whether they will be permitted to divert water
from Lake Michigan to flush waste treatment plant effluent
down the Illinois River or be required to return the
treatment plant effluent to the Lake. St. Louis, Missouri
recently passed a $95 million dollar bond issue for the
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construction of interceptor sewers and new sewage treatment
facilities, the whole purpose being to protect water quality
in the Mississippi River and in turn the users of this
water. The recent publication "Silent Spring" by Rachel
Carson has served to arouse many persons about our many new
2hstr.icels being manufactured and used and their effect on our
water resources including how they may be removed once they
are absorbed in water.
Perhaps our Congress foresaw these or similar situations
when they put into being the Federal Water Pollution Control
Act and later when they strengthened it with amendments.
The Water Pollution Control Act is broad in its
concepts and yet specifically covers areas where the Federal
government will act and assist in the control of water
pollution. The broad concepts include grants for construction
of sewage treatment works, enforcement of abatement measures
on interstate and navigable streams, research both through
grants and at Public Health Service laboratories, basic data
collection on water use and water quality, and comprehensive
planning for water quality management. Simply stated, the
law provides - delineation of the problem, solution or
know-how, incentive for construction, a plan for management
and finally a big stick for enforcement.
Specifically my talk deals with the comprehensive
plan for water quality management. The authority for this
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activity says that:
"The Secretary shall, after careful investi-
gation, and. in cooperation with other Federal
agencies, with State water~pollution control
agencies and interstate agencies, and with the
municipalities and industries involved,
prepare or develop comprehensive programs for
eliminating or reducing the pollution of
interstate waters and tributaries thereof and
improving the sanitary condition of surface
and underground waters."
The Public Health Service is presently making investiga-
tions of the Lake Michigan Basin as a part of a much bigger
study, the Great Lakes-Illinois River Basins Project. The
Great Lakes-Illinois River Basins Project when completed in
1967 will have a long-range water quality management program
extending to the year 2010 and including:
1. A determination of causes of water pollution
and the effects of such pollution on the
quality of water resources and on beneficial
uses.
2. Agreements on the desired beneficial water
uses and the water quality goals necessary to
accommodate these uses.
3- The pollution control measures necessary to
achieve the water quality goals, including the
establishment of a timetable for their
accomplishment.
In the development of water quality management plans
a determination of future water uses as well as goals of quality
for those uses are both difficult to arrive at and unavailable
as uniformly acceptable information.
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Let us take the water uses. Who is to determine and tell
people the purposes for which a given body of water may be
used? This is a matter of public policy and in a few States
a matter of public record - the waters having been classified
for particular uses. This, however, is not the usual case.
Some uses such as public water supply are quickly recognized
and protected. Others receive no recognition or protection
because of limited or unauthorized use.
It is inconceivable that any plan would arrive at the
beneficial water uses without the full knowledge of views and
desires of all those interests in the water concerned. Future
water uses must take into account the health, social, economic
and political considerations of the area- Plans for the long
range must of necessity be fluid and subject to revision as
conditions change or as indicated by public policy.
There are many specifications for one water use, public
water supply. The plant is designed in large part on the
basis of spatial relationships, i.e. - location of the water
source with respect to the distribution system and type of
structure (which in large part will dictate treatment units
used) to available sites. Everything, including the filters,
pipe, the valves, joints, chemicals, concrete, even the
paint, etc. going into the construction of the facility will
be measured against hard and fast industry specifications.
Everything, that is, except raw water quality. Standard design,
by and large, predominates and is expected to cover a wide
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range of water quality. However, many treatment plant
operators are saddled with the problem of producing a less
than quality product only because the available treatment
facility was never designed to cope with treatment problems
associated with the raw water supply. Costly and sometimes
futile additional treatment measures are added with the hope
that these stop-gap programs will handle the variations in
water quality that may exist or develop in any given supply.
Before any water quality management plan is developed
the requirements, criteria, objectives or goals must be
decided for each water use. The term "goals" is preferred
since it implies something for the future that isn't necessarily
available at the present time but toward which we can work.
The goals that will be required by our water users of the
future may be expected to be in line with others in our
advancing economy, namely, that they will be more rigid than
those presently thought practical.
These goals must be the expression of the best judgment
of qualified individuals. This judgment in our case is
provided by leaders from State agencies, municipalities,
industries, conservation and other interested groups acting
as a technical committee advisory to the Great Lakes-Illinois
River Basins Project. Work groups composed of Committee
members with GLIRBP staff assistance are concentrating on
four areas, viz., 1. Municipal Water Supply, 2. Industrial
Process Water, 3. Aquatic Life, Wildlife and Recreation,
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and k. The general category covering cooling water, commercial
shipping and waste water transport. The specific objectives
of each of these groups is to develop parameters where numerical
limits can "be set. I might say that good progress is being made
overall and that the target date of September for initial
reports from each group and a consensus report from the entire
advisory committee by late fall appears feasible.
The development of well-considered water quality goals
for each individual area studied by the Great Lakes-Illinois
River Basins Project could well have a far-reaching effect
on the use patterns of the concerned water masses.
The tenor of the times cannot brook vacilation, hesitation
or obstruction to progress in not only conserving our most
precious resource but in programming the best possible uses of
our waters in the future. Through professional self interest
your stake in this program is the development of the physical
requirements necessary to implement the goals using your
dedication as engineers to provide imagination and technical
competence. The country cannot expect less.
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PROJECT MANAGEMENT PLANNING IN WATER RESOURCE DEVELOPMENT ACTIVITIES *
by
Richard D. Vaughan #*
The Detroit River-Lake Erie Project was created as a result of
recommendations made at the first session of a Joint Federal-State of
Michigan Conference on pollution of navigable waters of the Detroit
River, Lake Erie, and their tributaries within the State of Michigan.
This conference was held March 2? and 28, 1962 in Detroit, Michigan
under the authority of Section 8 of the Federal Water Pollution Control
Act (33 U.S.C. 466 et seq.). The conference resulted from a request by
the Honorable John B. Swainson, then Governor of Michigan, for assist-
ance in identifying methods for correcting the sources of pollution
going into the Detroit River and subsequently into Lake Erie.
The objectives of the Detroit River-Lake Erie Project, simply
stated, are:
a. To determine the extent of pollution in the United
States portion of the Detroit River and the Michigan
section of Lake Erie.
* Presented at the American Society of Civil Engineers Water flesonro«»
Engineering Conference, Milwaukee, Wisconsin, May 13 - 17> 1963.
** Project Director, Detroit River-Lake Erie Project, Division of Water
Supply and Pollution Control, Public Health Service, Region V,
Department of Health, Education, and Welfare, Grosse lie, Michigan.
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b. To investigate principal sources of pollution in this
area and the contribution from these sources.
c. To determine the effect of pollution on various water uses.
d. To prepare a plan, or plans, for improving water quality
in the area.
To enable the recommendations which result from this study to be
timely and of significant value in meeting a current need, it was de-
cided by those concerned to strive for a Project duration of approximately
two and one-half years. This duration covers the period from the deci-
sion to have a study to the date of submission of a final report to the
conferees. Considering the complex nature of pollution, the major muni-
cipal and industrial complex involved, and the wide range of water uses
in the area, this duration does not appear to be excessive.
On the other hand, if the many complex questions -concerning sources
and effects of pollution in these waters are to be answered and recommen-
dations evolved to abate pollution which interferes with water use in the
area, effective planning must be accomplished.
Planning is important in almost any venture. When the undertaking
is complex, of significant magnitude, and limited in time, project plan-
ning becomes essential. Efficient use of financial and personnel re-
sources is imperative, and careful coordination and inter-relation of the
many activities which make up a water pollution control study are needed
to insure a completed report on time. Such planning is the responsibility
of the manager or director.
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3
In some scientific research or investigative projects, management
planning is relegated to a day-by-day or phase-by-phase operation. In
such instances, no attempt is made to ascertain personnel or financial
needs for any activity until that activity is begun. This has resulted
in considerable delays on one hand and needless waste of project re-
sources on the other. An attitude of "We will face things as they come."
is often prevalent in such operations. I believe the challenge and ur-
gent need for the results of water resource development studies preclude
such an approach and careful management planning is an essential part of
project operations.
Several types of planning are available to the manager and range
in complexity from sitting down and thinking the entire project through
and expressing these thoughts in narrative form, to sophisticated ap-
proaches using graphical techniques to tie together activities of an
overall undertaking. An example of the latter approach is the Program
Evaluation and Review Technique (abbreviated as PERT) developed for the
U. S. Navy in 1958.
This procedure first identifies the events or tasks which col-
lectively constitute the entire project. It then relates these items to
each other in a logical network which emphasizes not only the dependence
of one element upon another but also the importance of each event in
successfully completing the overall project. Estimates are made of the
time required to complete each step between events of this network. In
some cases estimates are made of the cost and personnel requirements to
complete the steps between events. With such information one may estimate
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4
the time, cost, and manpower requirements to complete the entire project
or a segment of it. In cases where manpower and funds are constant, the
time to complete a job efficiently utilizing these resources can be esti-
mated. In addition to the inter-relationship between the various events,
a critical path can be determined. This is simply the path along the
graphical network which represents the longest time required from the be-
ginning event of a project to the end. It is called "critical" because
to finish on schedule it is necessary to accomplish each event on the
critical path within the time estimates established for each step.
Therefore, any net delay along this pathway from beginning to end re-
sults in a similar delay in the completion of the project. On the other
hand, many other paths exist which are not critical and along which delays
of limited magnitude may occur and not result in a delay in the comple-
tion date of the project.
I shall not attempt to describe the precise methods of construction
of this chart since this information is contained in several sources but
rather comment on several key points associated with its construction and
describe the general use of the PERT chart in water resource development
activities.
Of rather obvious interest is the method of estimating the time
required to proceed or complete the step from one event to another. In
a project such as construction of buildings, the time required to accom-
plish a task such as painting a wall can be estimated with great accuracy
based on prior experience. The changing technology and needs of water
resource development and water pollution control activities have lessened
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5
the value of work experience in estimating duration for appropriate
tasks. Without such experience the time estimates must be in the nature
of educated guesses. It is therefore, important that these guesses be
made by one with not only a responsible position in the organization but
also one who understands the complexity of the situation and can make
reasonable estimates most likely to be successfully accomplished. Standard
PERT technique calls for a mathematical adjustment of three separate es-
timates - an optimistic, pessimistic and most likely. The wisdom of such
procedure in water pollution control studies might be questioned since,
lacking proper background, it is merely the adjusted average of three
guesses.
In making time estimates by any method, the prognosticator should
make certain allowances for events or tasks, the completion of which are
beyond his managerial control. Examples of this are services furnished
by others not under the line of command of the project manager. I be-
lieve a certain conservatism should pervade the estimating process for
these events. After all, dynamic direction and a devoted staff through
supreme effort can keep their activities going on schedule, while in
many cases little may be done to materially speed up the activities of
those over whom you have no control.
Figure 1 indicates a portion of a PERT chart developed for the
Detroit River-Lake Erie Project. It was developed after personnel and
funding needs had been determined using other methods, thus its major use
is limited to planning personnel resources and proper tjjning. The nota-
tions TE and TL in the block surrounding each event represent the earliest
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6
date the event may start and the latest date an event may be started and
not delay the final completion date of the project. The difference be-
tween two values represents "slack time" in weeks. Events which have no
slack time must be undertaken on the designated date or delay in the
project completion date may occur. Events on the critical path obviously
have no slack time. Such information furnishes the project manager with
information useful in the planning and distribution of manpower and finan-
cial resources at critical times during project operation.
On the Detroit Project the PERT chart is used in several ways as
an important tool in project planning administration. These are sum-
marized below.
a. Project progress towards the desired completion date can
be measured by comparison of actual progress with dates
on the PERT chart. The administrator can then react
accordingly as the situation dictates. This could pre-
vent both a needless uproar or Tuawarranted. .complacency.
b. Personnel resources can be shifted from one activity to
another as the latter becomes more critical. The cha*t
gives indications of areas where personnel can be spared
and areas where additional personnel will be needed and
when they will be needed. Management planning is there-
fore considerably aided.
c. The chart gives an objective basis for determining not
only whether a particular activity is lagging behind but
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7
also a measure of the importance of this delay to the
completion of the project on time.
d.,The chart gives the administrator ample notice of im-
pending personnel needs to allow recruitment of people on
a schedule which will make them available when needed -
not before or after.
The use made of the PERT system on the Detroit River-Lake Erie
Project could be expanded in future similar ventures if applied early in
the project planning stage. Incorporating cost features would furnish
another valuable aid in estimating overall costs prior to beginning
operations.
I would like to point out that this graphical approach to project
ariT~
management planning is not designed to supplement individual judgment or
common sense. It is unlikely that any mathematical or mechanical approach
can completely do this. The method does make the administrator think and
directly face his problems in order to better meet his responsibilities.
The field of water resource development is one of the most chal-
lenging and most important facing our nation today. A measure of the
success the many agencies participating in these activities may have will
certainly depend upon the early availability of reliable plans of action
based on study and investigation. Careful management planning is essen-
tial to efficiently utilize available personnel and financial resources
in evolving water resource development plans capat&e of meeting the
challenges of the future.
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SEARCH FOR OFFICE,
DECISION MADE TO
START DETROIT RIVER
—^
TL'i 4-»-«2
22
ADMIN PROCEDURES
PERSONNEL BEGUN
TE'I 4-9-62
TL-3 4-23-62
23
PERSONNEL COMPLETED
TE-3
TL-5
s le
ASSIGNMENT OF KEY RECONNAISSANCE >ND
PERSONNEL FOR PLANNING OF SAMPLING
* ACTIVITIES COMPLETED • — —
t.-IO
I.-IO .
n-18 ^
. 1 ..
(•'1
8
PERSONNEL FOR
BIOLOGIC ACTIVITIES
COMPLETED
TE- II 6-18-62
TL-24 9-t7-62
li-3 r
79
4-23-62
fl-T-62
TL-8
24
j-
HIRING OF 3
LABORATOR
PERSONNEL
TE-3
TL-5
17
RECONNAISSANCE AND
PLANNIN'O Of SAMPLINQ
TE-12 6-25-62
TL- 12 6-2S- 62
7
ASSIGNMENT OF KEY
PERSONNEL FOR
ED
TE-II I 6- 16-62
TL-12 j 6-25-62
PL ANNING AND
BIOLOGIC STUDIES
BEGUN
TE-14 .
TL-27
7-9-62
10-8-62
14 93
PATTERN STUDIES
COMPLETED
TE-19 6-13-62
TL -59 5-20-63
73
PLANNING FOR DOME STIC
WASTE SURVEY BEGUN
!..>
STUDY
TE-20
TL *60
74
6-20-62
5-27-63
PLANNING FOR DOMESTIC
WASTE SURVEY
COMPLETED
tfl-39
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*•"'
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in
60
PLANNING A
BIOLOGIC S
COMPLETED
TE-33
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94
FOR CUR
STUDY
REN
TE* 26
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75
DOMESTIC *
SURVEY BE
Figure 1
Portion of PERT Program
Plan
U.S. Department of Health,
Education, and Welfare,
Public Health Service -
Region V, Water Supply and
Pollution Control, Detroit
River-Lake Erie Project
ASSIGNMENT OF KEY
PERSONNEL FOR
ENGINEERING EVALUATION
ACTIVITIES COMPLETED
PRELIMINARY DATA
PROCESSING PLANNING
COMPLETED
8-20-62
ll-S-62
—
1 t.-IB r
fa-18
tt-ie
WATER OVE
ACTIVITIES
TE-19
TL-26
13
ASSIGNMENT
PERSONNEL
SLUDGE STU
COMPLETED
TL-S6
RFLOW
COMPLETED
8-13-62
tO-l-62
OF KEY
FOR
DIES
4-29-63
15
PERSONNEL
VALUE STU
COMPLETED
TE-19
TL-61
FOR WATER
IES
8-13-62
6-3-63
tt*l t
!••!
t««l
OVERFLOW
TE-20
TL-27
89
SLUDGE ST
PLANNING
TE-20
TL'57
STUDY
8-20-62
10-8-62
UDIES
JEGUN
8-20-62
5-6-63
97
WATER VALL
TE- 20
TL-62
E STUDY
8-20-62
6-10-63
tt*6 |
tt-6
!••• ^
OVERFLOW
TE*Z6
TL-33
90
SLUDGE STl
PLANNING C
TE-26
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96
PLANNING C
FOR WATER
STUDY
TE-26
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PERSONNEL FOR
INVENTORY ACTIVITIES
1 COMPLETED
COMPLETED
COORDINATED PLANNtNO
BEGUN FOR ECONOMIC
AND DEMOGRAPHIC
' STUDIES
COORDINATE
COMPLETED
ECONOMIC A
' PEMOOR*PHI
TE-19
TL-42
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COMBINED SEWER OVERFLOWS*
fcy
CARLISLE PEMBERTOW, JR.**
The intensive water quality survey of the vaterways In
the Chicago area which has been carried on by the United States
Public Health Service during the past two years was described
in an earlier paper this afternoon. In carrying out this study,
it was desirable that we be able to identify the sources of the
total pollution loads which we found in the streams. The loads
contributed by the sewage treatment plants were readily identified
through our sampling programs and plant reoords made, available- to
us by the Metropolitan- Sanitary District of Greater Chicago.
However, there remained a substantial ho per cent of the total
load to be accounted for from other sources. It was felt that
overflows from combined sewers during storms would be an Important
source of the unidentified pollution load. It was therefore
decided to secure data on the quality and quantity of overflows
^Presented at the Water Resources Engineering Conference of the
American Society of Civil Engineers, Milwaukee, Wisconsin,
May 13-17, 1963.
**Hydraulic Engineer, Great Lakes-Illinois River Basins Project,
Water Supply and Pollution Control, Region V, Public Health
Service, U.S. Department of Health, Education, and Welfare,
Chicago, Illinois.
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for use as a basis for estimating the total load contributed
to the streams by the combined sewer system.
The history of underground drainage in Chicago began
with the construction of the first city sewer system in 1856.
The system was designed to carry both storm water and sanitary
sewage to the Chicago River and to Lake Michigan, and served
about seven square miles including the present "Loop" area.
In the 10T years since 1856, the Chicago combined sewer system
has been expanded to include over 3,600 miles of sewers serving
190 square miles with 3.5 million population. Many of the
suburban municipalities in the Chicago Metropolitan Area also
are served by combined sewer systems which discharge storm
runoff into the waterways of the area.
For many years these combined sewers discharged, all fLonrs
directly to the streams, of which some were- tributary to Lake
Michigan, and others tributary to the Illinois River. In 1&90,
the Metropolitan Sanitary District of Greater Chicago was
organized and initiated construction of a system of sanitary
and combined interceptor sewers serving Chicago and many of the
suburbs. The interceptor system is designed to conduct dry
weather flows to the various sewage treatment plants operated
by the Sanitary District, and to discharge storm runoff through
overflow structures and pumping stations, to the Des Plaines,
Chicago and Calumet Rivers, the Chicago Sanitary and Ship Canal,
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3
and the Calumet Sag Channel. The drainage pattern for the area
is shown on Figure 1.
Storm water overflows to the Des Plaines River follow the
natural course of that river to the Illinois River. Storm water
overflows to the Chicago River are also tributary to the Illinois
River, since the natural direction of flow of the Chicago River
was reversed by the construction of the Sanitary and Ship Canal.
The overflows in the northern part of the city discharge to
North Branch Chicago River and to the Worth Shore channel which
was constructed in 1910. The Calumet-Sag Channel, completed in
1922 by the Sanitary District, was designed to reverse the flow
of the Calumet River from Lake Michigan to the Chicago Sanitary
and Ship Canal. This flow is regulated by means of the Controlling
Works at Blue Island, except during infrequent heavy storms when
runoff threatens to cause flood damage along the Calumet-Sag
Channel. At such times, the control gates are closed, forcing
Calumet River flood flows to Lake Michigan. If storm runoff to
Calumet-Sag Channel causes the water surface to rise above that
of the Calumet River, the control gates may be opened to permit
flow out of the Calumet-Sag to Lake Michigan, as a flood relief
measure. Thus, storm water overflows to the Calumet-Sag Channel
and Calumet River are usually tributary to the Illinois River,
but may occasionally go to Lake Michigan. A new lock and control
gates, the Thomas J. O'Brien Lock and Dam, built by the U. S. Army
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Engineer District, Chicago, is located in the Calumet River
just lakeward from the confluence of the Grand Calumet and
Little Calumet Rivers. After removal of the old Controlling
Works, Calumet-Sag Channel flows will be regulated at the new
lock.
Pollutional Aspect of Combined Sewer Overflows
The discharge of raw sewage and industrial wastes mixed
with storm water during periods of storm runoff constitutes a
significant intermittent source of pollution of the waterways
in the Chicago area. The physical extent of the problem is
indicated by the number of overflows, approximately 200 on the
main channels, and a large number on tributary streams such as
the Des Plaines River, the North Branch Chicago River and the
Little Calumet River.
Pollution of streams in a metropolitan area may result
in economic loss through curtailment of recreational use of the
waterways, increased water treatment costs, reduced property
values, corrosion of boats and nearby structures, and, under
certain conditions, the loss of industrial development. The
esthetic value of the streams is destroyed by unsightly floating
material, murky waters and unpleasant odors. The biological
life of the stream is adversely affected by low oxygen values
resulting from the oxygen demand of sewage and industrial wastes.
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5
Pleasure boat operators either avoid the waterways or use them
as a means of access to less polluted waters.
More important, however, is the danger to public health
from the pathogenic bacteria and viruses which may be present
in raw sewage. Although the concentration of BOD and sewage
solids in the combined sewers, with the exception of the first
flush, may be reduced by dilution during runoff periods, the
pathogens remain a serious menace to any public use of the
streams receiving these discharges.
The percentage of the annual sanitary and industrial waste
flow spilled during overflows has been estimated by several
investigators to be in the range of three to five per cent for
sanitary sewage interceptors designed for one and one-half to
three times the average dry weather flow. However, the first
slug of such wastes may be several times the strength of the
normal sewage flow.
In 19^7, J. E. McKee (l), reporting on studies for sewage
disposal in the Merrimack River Valley Sewerage District in
Massachusetts, showed that, although only a small per cent of
the annual sanitary sewage flow is lost in storm water overflows,
a large per cent of the sewage present in the combined sewers
during rainstorms is lost during overflows. McKee's studies
also showed that with interceptors designed for one and one-half
to three times the average dry weather flow, overflows will occur
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every five or six days on the average during summer months.
Ihus the receiving stream would be seriously polluted for short
but frequent periods during rainstormsj this would greatly restrict
the recreational use of the stream.
MeKee's study also showed that increasing the capacity of
the interceptors for the purpose of reducing the frequency of
overflows sufficiently to avoid pollution of recreational waters
was generally not economically feasible. Studies reported by
C. L. Palmer (2) for Detroit, Mich., E. Riis-Carstensen(3) for
Buffalo, N. Y., C. F. Johnson (4)(5) for Washington, D. C.,
T. R. Camp (6) for Concord, N. H., ¥. W. Homer (7) for St. Louis,
Mb., S. A. Greely and P. E. Langdon (8) for New York City,
H. H. Senses and others (9) for Kansas City, Mo., and A. L. H.
Gameson and R. N. Davidson (10) for Northampton, England, have
supported the findings of McKee. However, as Johnson (5) pointed
out, where the highest recrational use of a stream is desired,
and where esthetic values are highly important, such as in the
nation's capital, it may be practicable to design interceptors
for as much as 30 times the average dry weather flow.
The public health problem of pathogens in combined sewage
was emphasized by Camp (ll) in a report of studies of chlorination
of raw sewage for bacteria kills and virus inactivation. British
practice in the treatment of combined sewage was reviewed by
H. Romer and L. M. KLashman (12).
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7
The study of combined sewer overflows in Chicago was
undertaken to determine the pollution loads discharged to the
streams from selected combined sewers during storms. The total
pollution load entering the streams from the sewer system was
estimated by extension of the observed data.
Flows have been measured and sampled in two combined
sewers, the Roscoe Street sewer on the north side of the city,
and the Union Avenue sewer located just south of the Loop area.
However, due to the limited amount of data collected at the
Union Avenue site, only the Roscoe Street data were used in this
analysis.
Study Area
The drainage area of the Roscoe Street sewer is about
five miles long and varies from one to three miles wide with a
total area of 8.6 square miles. The City of Chicago follows
the practice of providing interconnections between major sewers
serving adjacent drainage areas. This provides needed relief
drainage for localized storms, together with economy of design.
However, it often results in indistinct drainage boundaries.
About 25 per cent of the Roscoe Street sewer area is inter-
connected with adjacent systems. The interconnected area was
assumed to be tributary to the Roscoe Street sewer for the
purpose of this study. The drainage area slopes downward from
west to east, with an average fall of about 10 feet per mile.
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8
land use is principally residential, with, single-family
dwellings predominating. Land use data obtained from the Chicago
Area Transportation Study (13) shows that kk per cent of the
total area is in residential use, 32 per cent is devoted to
streets and alleys, with the remaining 2k per cent divided between
commercial, industrial, public bxiildings, transportation, public
open space and vacant land uses. Imperviousness factors derived
by C. J. Keifer (l4) were applied to these land use areas. The
impervious surface is estimated to be 42 per cent of the total
area.
The 1956 population was 144,300 (13), with a population
density of 26 persons per acre.
Hydraulic Measurements
At the point where dry weather flow is diverted to the
Metropolitan Sanitary District interceptor sewer, the Roscoe
Street combined sewer is a twin 12 ft. X 12 ft. horse-shoe
section, with an invert slope of 0.0005, and a nominal capacity
of 1,200 cubic feet per second (cfs) when flowing full. Ports
are located about every 150 feet in the common wall to equalize
flow. At the diversion chamber, the invert of the sewer is
about 7 feet below river level. Flap gates in the outfall
section prevent backflow from the river. The water level in
the sewer must rise above the river level before overflow begins,
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9
thus providing considerable storage in the sewer system, which
prevents overflow during rains of low intensity, and reduces
the overflow during larger storms.
Float type water stage recorders were installed in float
wells in manholes located k-60 feet and 1930 feet upstream from
the diversion chamber. These gages indicate the hydraulic
gradient in the sewer, and discharge was determined from computed
rating curves.
Diversion to the interceptor is through a k ft. X k ft.
sluice gate which was open half-way during the period of study.
This gate is motor-operated, and equipped for automatic operation
based on water level in the interceptor. The sewer invert is
raised 2 ft. at the downstream side of the diversion chamber,
forming a dam to divert dry weather flow.
Float-type water stage recorders were installed upstream
and downstream from the sluice gate. Discharge was determined
from a computed rating curve for the sluice gate opening. The
discharge coefficient for the gate opening was determined from
current meter measurements made just upstream from the gate.
Rate of flow to the river was determined as the difference
between total flow in the sewer and the diverted flow during
the period of overflow. The overflow period was determined by
observation of the flap gates and by interpretation of gage
height record on the recorder charts. It was found that water
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10
levels remained nearly constant during the overflow period
so that storage corrections were not required.
Two recording rain gages were installed to supplement
the rainfall data from existing rain gages.
Sampling Procedure
In order to man the sampling operation ahead of an
expected overflow, an alerting procedure was set up, in which
the U. S. Weather Bureau notified Project supervisory personnel
when a rainfall of about 0.1 inch per hour with a total of
around 0.5 inch was expected. The supervisor then notified
sampling personnel, laboratory personnel and an engineer from
the hydraulics section.
Bulky sampling equipment such as ice chests and sample
containers were stored previously in the underground diversion
chamber, so that sampling personnel would have a minimum amount
of equipment to transport to the site.
Sampling procedure before and during a storm was:
Bacterial samples at diversion chamber and on outfall
sewer, hourly throughout.
BOD samples at both locations, hourly before water level
started to rise, every 15 minutes during the rise and overflow
periods, and every 30 minutes after overflow stopped until the
water level receded to low stage.
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11
DO samples on the outfall sewer only, with same frequency
as for BOD samples.
During periods of runoff and overflow vhen samples -were
"being taken, an engineer from the Project was on hand to make
sure that gages were functioning properly, and to observe flow
conditions.
Background sampling of dry-weather flow was carried on
during October, 1961.
Considerable difficulty was experienced in obtaining
adequate samples of storm flow. The main factor was the extremely
difficult problem of making accurate quantitative precipitation
forecasts for relatively small geographical areas. It was found
that an average rainfall intensity as low as 0.04 in./hr. would
produce an overflow under certain conditions. The lag time
between beginning of rainfall and overflow was usually about
two hours, so that sampling should have been started within
about one hour after rainfall began. This proved to be very hard
to accomplish when rainfall occurred after regular working hours,
due to time required to recruit sampling personnel, travel time,
etc. When rainfall occurred without advance notice during
regular working hours, sampling personnel were often in the
field on other assigned duties and not readily available. I
might say here that we have found that it usually rains at night,
on weekends, or not at all. In all, adequate data have been
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12
obtained from only five storms. The study is continuing through
the spring season in an effort to collect more data. Automatic
sampling equipment has "been built for a similar study in Detroit,
and although the installation of automatic equipment is usually
expensive, it is recommended.
Dry Weather Flow
Average dry weather flows were determined from the sluice
gate rating curve for periods considered to be representative of
the entire period of gage record. The estimated annual average
dry weather flow is 45 cfs, or 29.1 million gallons per day (mgd).
This is equivalent to about 200 gallons per capita per day.
Samples of dry weather flow in Eoscoe Street sewer were
collected on 23 days during the period September 27 to November 2,
196l. The estimated annual average dry weather 5-day biochemical
oxygen demand (BOD) load, based on the average flow and the
average concentration reported in the laboratory analyses, is
25,200 pounds per day. This is equivalent to 0.175 pounds per
capita per day.
Storm Flow
During 11 months of gage record (Oct.-Dec. 1961 and April
to November 1962) there were 3^ storms which caused overflow.
The average duration of overflow was about k hours, and the
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13
accumulated time of overflow was 1.7 per cent of the total
time. During this period of gage record the rainfall at
Midway Airport was 76 per cent of normal. Runoff averaged
39 per cent of rainfall with considerable variation between
storms, as would be expected.
Bacterial Samples
Bacterial samples were studied in the laboratory to
determine the densities of coliform bacteria and fecal
streptococci, using the membrane filter procedure. The mean
coliform density in the overflow was 1,3^1,000 per milliliter
(ml.). The fecal streptococcus density was 575,000 per ml.
Saese figures are arithmetic averages of 19 sample determinations
from four overflows with a total time of 30.5 hours. It is
evident that periodic discharge to the waterway of this type of
pollution would make any personal contact use of these waters
dangerous from the standpoint of public health.
Chemical Samples
Samples from the diversion chamber and from the overflow
section of the sewer were analyzed in the chemical laboratory
to determine concentrations of 5-day BOD, chemical oxygen demand:,
chlorides, alkyl benzene sulfonate (ABS), nitrogen, phosphates
and solids.
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Ik
Suspended solids concentrations in the overflow sewer
varied widely, depending on storm rainfall and antecedent
conditions. During one storm in which 3,17 inches of rain fell
in seven hours (about 10-year frequency), it is estimated that
633,000 pounds of suspended solids were discharged during an
overflow period of 15 hours, with concentrations as high as 600
milligrams per liter (mg/l). During three weeks preceding this
storm, total rainfall amounted to only 0.22 inch. This allowed
considerable time for a build-up of solids in the system, which
were then flushed out by the high flows resulting from the storm.
The solids content of the surface wash from this storm would also
be high. Hie suspended solids concentration for four other
storms averaged about 1.5 times the average dry weather flow
concentration. !Ehe total load discharged during these storms
was 5-5 times the dry weather suspended solids load for the same
number of hours.
!Ehe average 5-day BOD concentration during five overflows
was less than one-half the average dry weather flow concentration.
However, the total BOD load discharged during these overflows was
2.5 times the dry weather BOD load for the same number of hours.
The 5-day BOD concentrations were found to vary with time
during storm periods as shown in Figure 2. By extension of these
data the estimated total BOD load to the canal system from overflows
was calculated.
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15
The total volume of overflow in each 30-minute period,
after start of overflow, was computed for 31 storms which
occurred during October-December 196l and April-September 1962.
Gage records for October and November 1962 were omitted to avoid
duplication of months. The average BOD concentration corresponding
to each 30-minute period was taken from Figure 2 and the load
discharged during each period was computed. The total load thus
obtained, when averaged over the 9-mon"th period, would be
equivalent to 1,000 pounds of 5-day BOD per day. It was considered
that the annual average daily load would not differ appreciably
from the 9-TQ.oicith average.
It was assumed that the frequency, duration, and volume per
unit area of the overflow from the Roscoe Street sewer would be
representative of the overflows to be expected from all sewered
areas tributary to the Sanitary Canal. This is recognized as an
oversimplification of the complex relationships between rainfall
intensity, time of concentration, imperviousness, storage in the
sewers below river level, etc. However, on the basis of the
information available at this time, the assumption is considered
reasonable. A study of an adequate number of sewers to define the
overflow characteristics of the entire tributary area is beyond
the scope of the GLIKB Project.
It was further assumed that, in the tributary area of each
main treatment plant, the ratio of the total overflow BOD load to
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16
the total BOD load received at the plant would be equal to the
ratio of the Roscoe Street overflow BOD load to the total BOD
load diverted from the Roscoe Street sewer into the MSD
interceptor.
The total BOD loads received at the treatment plants are
not available for 1962 , when most of the Roscoe Street data
were collected, therefore average loads based on records for
1957 through 196l were used. The BOD load to the Stickney Plant
was adjusted to delete that part of the load from suburban areas
where the sewers overflow to the Des Plaines River.
The total BOD load diverted from the Soscoe Street sewer
to the MSD interceptor was not determined, since data for storms
not producing overflows have not been analyzed at this time.
Therefore, the dry weather BOD load was used for this purpose.
The 5-day BOD overflow load in each treatment plant area
was computed separately:
North Side: 178,400 XOW. = 7>100 lb./aay
Stickney: 887,300 XOIO. = 35,500 lb./dfly
Calumet: 106,500 X_
TOTAL 46,900 Ib./day
The 5-day BOD load to the canal system thus computed is
about 19 per cent of the total BOD load, as determined from our
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17
sampling program which covered five months in 1961 and 1962.
Conclusions
A study vas made of flow rates and composition of overflows
from a large combined sewer serving a residential area of 8.6
square miles with a population of l¥j-,300.
Overflows occurred during 1.7 per cent of the time, in
a 14-month period when rainfall was about 75 per cent of normal.
Gross bacterial pollution was discharged during overflows,
limiting the use of the receiving waters from a public health
standpoint.
Suspended solids concentration in the overflow was greater
on the average than that of dry weather flow, with considerable
variation associated with rainfall intensity and time since the
last storm.
The 5-day BOD concentration. 1» the o"SBr:flo¥ averaged about
one-half that of dry weather flow, and was found to decrease- wltb
time after overflow started. The total BOD load discharged during
overflows was 2.5 times the dry weather BOD load for the same
number of hours.
By extension of the observed data, it is estimated that
the BOD load resulting from combined sewer overflows accounts
for about 19 per cent of the total BOD load in the canal system
serving the Chicago area.
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18
REFERENCES
1. McKee, J. E. Loss of Sanitary Sewage through Storm Water
Overflows . Journal of the Boston Society of Engineers,
3^, 2, 55 (April 1947).
2. Palmer, C. L. The Pollutional Effects of Storm-Water Overflows
from Combined Sewers. Sewage and Industrial Wastes, 22, 2,
154 (February 1950).
3. Riis- Cars tens en, Erik. Improving the Efficiency of Existing
Interceptors. Sewage and Industrial Wastes , 27, 10, 13.15
(October 1955).
k. Johnson, C. F. Nation's Capital Enlarges its Sewerage System.
Civil Engineering, 28, 2, 56 (June 1958).
5. Johnson, C. F. Equipment, Methods, and Results from Washington,
B.C., Combined Sewer Overflow Studies. Journal WPCF, 33, 1,
721 (July 1961).
6. Camp, T. R. Overflows of Sanitary Sewage from Combined Sewerage
Systems. Sewage and Industrial Wastes, 31, k, 38! (April 1959).
7. Shifrin, W. G., and Horner, W. W. Effectiveness of the Inter-
ception of Sewage - Storm Water Mixtures. Water Pollution
Control Federation, Philadelphia Convention, (October I960).
8. Greeley, S. A., and Langdon, P. E. Storm Water and Combined
Sewage Overflows. A. S. C. E._ Journal of Sanitar^Engineering
Division, 87, SA 1, 57 (January 1951J.
9. Benjes, E. H., Haney, P. D., Schmidt, 0. J., and Yarabeck, R. R.
Storm-Water Overflows from Combined Sewers. Journal WPCF, 33,
12,1252 (December 1961).
10. Gameson, A. L. H. , and Davidson, R. N. Storm-Water Investigations
at Northampton. The Institute of Sewage Purification, Annual
•Conference, I.la.pApflnn, (.Timo 1062 ).~~
11. Camp, T. R. Chlorination of Mixed Sewage and Storm Water. A.S.C.E.
Journal of Sanitary Engineering Division, 87, SA 1, 1 (January 1961),
12. Romer, H. , and KLashman, L. M. The Influence of Combined Sewers
on Pollution Control. Public Works, (October 1961.)
13. Land Use and Population Ease Maps from the Chicago Area
Transportation Study, ^-812 West Madison Street, Chicago bk, Illinois.
Ik. Keifer, C. J., Sewer Planning Division, Bureau of Engineering,
City of Chicago. Direct testimony in case of States of Wisconsin,
Minnesota, Ohio, Pennsylvania, Michigan and New York, Complainants
vs. State of Illinois and the Metropolitan Sanitary District of
Greater Chicago, Defendants; United States Supreme Court, October
term 1961, p. 19239-
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FIG. I- MAJOR DRAINAGE -Jjp
01234 — —
Miles
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160
150
140
130
120
110
_IOO
\
01 90
E
• 80
a
o
70
60
< 50
40
30
20
1 I I
I 0 I
HOURS
234
Before Overflow
After Overflow
FIG. 2-BOD CONCENTRATION
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LAKE MICHIGAN CURRENT STUDIES*
by
W. Q. KEHR**
The U. S. Public Health Service has been charged with the
responsibility of conducting comprehensive water quality studies in
the several Great Lakes, and developing programs for insuring that the
quality of these waters will be satisfactory for present and future
water uses. Projections of future economic, industrial and population
growth can be made, and from these estimates can be developed the
magnitude and character of future waste loads. There remains,however,
the determination of the impact of these loads on receiving waters and
the quality of the waters during the period of assimilation and
recovery.
Numerous studies have been made of the impact of waste loads on
streams, and mathematical models have been developed which permit
prediction of the rate of self purification. In large bodies of water
such as the Great Lakes the impact of wastes on water quality, the
rate of dispersion of waste loads?and the ability of these large water
masses to recover must be presently based on theoretical considerations.
•^Presented at the American Society of Civil Engineers Water Resources
Engineering Conference, Milwaukee, Wisconsin, May 13-17, 1963.
##Project Director, Great Lakes-Illinois River Basins Project, Water
Supply and Pollution Control Division, Public Health Service, Region
V, U. S. Department of Health, Education, and Welfare, Chicago,
Illinois.
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- 2 -
Wastes mix with and are moved by the waters into which they are dis-
charged. Lake waters are not confined to a channel and move in
accordance with the natural forces acting upon them. The principal
driving forces are the winds, which vary both in magnitude and
direction. An understanding of the relationship between the winds and
the currents that they create would, therefore, aid materially in
predicting the direction in which wastes would be moved and which
water uses might be affected. Further, studies of the rate of disper-
sion or mixing of the wastes with the greater volumes of lake water
would permit predictions of the probable concentration of wastes which
might reach and affect nearby water uses.
Project goals are to study and develop data which will assist
in providing answers to these important problems. It is anticipated
that a study of simultaneous observations of certain meteorological
variables and water currents will result in a usable method of water
current prediction. To stay within the time allotted for this paper
it will be necessary to limit the discussion to the equipment and
techniques employed in conducting studies of mass water movements in
the Great Lakes.
Water speed, direction and temperature data are being gathered
by automatically recording strings of instruments at 12 locations in
Lake Michigan. It is hoped that at least 30 more stations will be
added this spring. Data will be gathered every half hour during the
winter and every twenty minutes during the other seasons for at least
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- 3 -
a full year. In addition, air speed, direction and temperature data
will also be recorded at the same intervals at some of the stations
during the more clement 3/4 of the year. Lake Michigan is about 300
miles long, 70 miles wide and 275 feet deep, on the average. The
greatest depth recorded on charts is 923 feet. Each station, there-
fore, represents an area of about 500 square miles and a volume of 28
cubic miles; the horizontal sampling network is quite sparse.
Slide 1
The first slide shows the station distribution. Vertically,
at each station, data is collected at 30, 50, 75, 100, 200, and every
hundred feet thereafter. Water depth at the shallowest stations is
about 65 feet and at the deepest 850 feet.
Slide 2
This slide shows a typical station, which consists of a surface
float, a subsurface float, two anchors, current meters, temperature
recorders, and various connecting lines.
Slide 3
The next slide shows the surface float which is used during the
more clement portion of the year. The float is made of fiberglass
foam wrapped in the shape of a toroid doughnut eight feet in diameter
and two and a half feet thick. A tower tripod ten feet high is bolted
to the float. Two platforms on the tower support a navigation light
and wind and temperature recording instruments. Three twenty-foot
chains are shackled at different points on the underside of the float.
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- 4 -
lower €ndfl-
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- 5 -
current meter make up each pair.
Slide 6
This slide shows a typical pair, with a current meter shackled
directly below a temperature recorder.
Slide 7
The next slide shows a line sketch of the inside of a tempera-
ture recorder. Temperature is sensed by a hydrocarbon liquid filled
bourdon tube assembly. The liquid filled bulb is sealed into a well
in the base of the temperature recorder. To give good thermal con-
duction between the bulb and the base, the well is filled with ethylene
glycol. The bulb is connected by capillary tubing to the spiral
bourdon tube. As temperature increases, the hydrocarbon liquid expands
and liquid pressure in the tube rises, causing the spiral to unwind and
impart a rotary motion to its center. This rotary motion moves a pen
point which scribes a trace on a two inch wide strip chart. The chart
paper is 50 ft. long and is advanced about 0.0? inches at a time upon
command of a precision clock timer. There is one advance every twenty
minutes, except in winter when there is one advance every half hour.
The longer interval in winter ensures sufficient chart and battery
life in the event that ships which service the equipment are delayed
by ice and bad weather. In the interval between advances, the pen
scribes the temperature range on the chart paper. The temperature
recorder is about 5 inches in diameter, two feet long and 25 pounds
in weight in air. Its weight in water is about 5 pounds. Recording
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- 6 -
rerge is -2° to ':-3°C. Accuracy is stated by the manufacturer to be
about plus or minus 0.25°C. Thermal lag time is about 15 seconds per
centigrade degree.
Slide 8
This slide snows a line skobch of the insic.e of a current meter.
There is a direction vane on the upper end of the case and a speed
sensing rotor on the lc,-rcr. Magnets are attached to each. End caps of
the pressure case are not pierced, and other iragnets inside the case
trade those on the i^uso^b,, HID vcine .follower magnets are attached to
a seven track coding disk which either doss or does not allow light to
pass from a source into each of seven fiber optic light tubes. The
trjes cany th:'s light or nc-Li^Iit information to r. display panel '- hid-
is photographed by a 16 joi novie camera> The vane gives the direction
of water motion relative to the iiistrc^e'Vr, c"ro. A magnetic compass,
si ilerly equipped with e. coding disk and fiber optics, gives the
orientation of the in3brrr.or.it case to irr;y?eJL-,ic north. The rotor
follower magnets c.rc attached to ?. u\;o trr,ck Jirht cliopprj? with fJLsr
optics. One ].e"rel rives a light pni.j.r.o fcr e.;,cli re-tor revolution. The
second level gives a LigY'. niJ.T? fcr u7c r.y te/.t.h rotor revolution.
Besides the seven vans tr.'.eks,, \.h-j eer:>n o.\rpass tracks, and the two
:.'otor tracks, there is a continv.c"^. reference line and also a track
for the light pulse parking bho V. •.pj.nAr.r; of e.-.ch observation, making
a total of 18 tracks i-uni.'iny Io^gi-Vud:irv,lj.y f.l.cnx the movie film. A
precision sequence tinier turns on the light sources and advances the
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— 7 —
film continuously at a constant rate for 50 seconds. The lights are
then shut off for 19 minutes and 10 seconds, when the next cycle starts.
The total cycle time is therefore 20 minutes, except in winter, when it
is 30 minutes because of a longer time between recordings. The several
temperature recorders and current meters at any station do not necessar-
ily cycle simultaneously. The advantage of a central control system to
provide simultaneous operation is outweighed by the possibility of total
loss of 3 to 4 months' data from a station in the event the central
control system failed. The current meter is about 9 inches in diameter,
6 feet long and 90 pounds in weight in air. Its weight in water is
about 10 pounds. Speed recording range is about 0.05 to 10.1 feet per
second. Accuracy is stated by the manufacturer to be about plus or
minus 10^ from 0.05 to 0.5 knots and 2$ above 0.5 knots. Direction
recording accuracy is plus or minus 7° from 0.05 to 6 knots.
Slide 9
This slide shows the Savonius-type rotor used in the current
meter. The rotor consists of two sections each having two semicircular
blades. In each section the blades are mounted 180° apart and opposed.
The top section is oriented 90° to the lower one, giving a four-lobed
torque distribution. The rotor is constructed by gluing together
pieces moulded from polystyrene. The pivots of the bearing assembly
consist of tungsten carbide rods 0.093 inches in diameter and ^ inch
long which are molded into phenolic holders screwed to the rotor. The
bearings in which these pivots ride are mounted one on the lower end
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- 8 -
cap of the instrument pressure case and one on the end plate. The bear-
ings consists of a stainless steel socket head screw with a broached
hole in one end. This hole is 0.100 inches in diameter and is highly
polished. A highly polished tungsten carbide end stone is set in the
bottom of the hole. The end plate bearing is adjusted to give about
0.009 inches end throw. There are six standoffs holding the end plate,
each 5/8 of an inch in diameter and about 8 inches long, giving about
half an inch clearance below and 3/4 of an inch above the rotor.
Present test results indicate that tilting the rotor's axis more than
five degrees from the vertical produces significant errors in the data.
In addition, significant variations in meter output result in the
presence of 2 foot vertical particle motions with periods of 5 to 10
seconds in the presence of a half knot current. These considerations
resulted in a decision to have the shallowest current meter at least
thirty feet deep and to attach the surface float directly to an anchor,
as previously described, instead of directly to the subsurface float.
Marine fouling has a marked effect on rotor output, evert -when
not very severe. Coating the rotor with an anti-fouling. aerosol
similar to petroleum jelly helps to alleviate the problem. The time
for 63$ response to a step change is nominally 1 second for accelera-
tion and 2| seconds for deceleration, both taken about 0.2 knots for a
speed change about equal to the mean speed. The response is better at
higher speeds and deteriorates rapidly as the current speed approaches
zero. The effect of natural turbulence on meter performance is unknown
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- 9 -
and may be significant for turbulence with certain spectra. The
spectrum of turbulence in Lake Michigan is not known. Such turbulence
would be expected to be of short duration at the depths selected and
readily identified from the readout.
A number of current meter stations are now in Lake Michigan.
The following slides taken last November and December will give an
idea of how they are launched.
Slide 10
(Slide) The instruments, which have previously been tested and
loaded with fresh batteries and film or chart paper, are laid out end
to end along one side of the ship and then shackled to each other or
to the proper lengths of 5/8 inch diameter braided polypropylene. The
braided polypropylene is relatively non-rotating, even under load. A
subsurface float is shackled to the upper end of the instrument line
and a length of 3/8 inch BBB chain is shackled to the deepest instru-
ment and the anchor. The aliminum fins strapped to the current meters
tend to reduce random rotary motions of the case.
Slide 11
The next slide shows the anchor being put over the side. It
will be lashed to the rail with one inch diameter manila rope and the
crane hook removed. In addition to the chain attaching the instru-
ments, a length of either 5/Q inch or 3/4 incn polypropylene rope will
also be shackled on. The polypropylene, which is longer than the
water depth, will be laid out in a number of neat coils on the deck so
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- 10 -
that it can pay out freely. The free end is shackled to the second
anchor, which is sitting on the deck. When all is ready, the instrument
string is put over the side, starting at the subsurface float end. When
the instruments are overside, people get well clear of the polypropylene
on deck and the anchor is launched by cutting the manila rope with an
ax. The sinking anchor pulls down the instrument string and the sub-
surface float. The second anchor, still attached to the first by the
polypropylene rope, is now put over and made fast to the rail with one
inch manila. One end of a second length of polypropylene is also
attached to this anchor and the far end shackled to the bridle ring of
the surface float. The surface float is now launched, but held to the
side of the ship, well clear of the anchor. The polypropylene is
coiled freely, as before, and when all is ready, the ship is moved
slowly away from the instrument string. When the line between the
anchors goes taut, the manila holding the second anchor is cut, com-
pleting the launching. All that is now visible on the surface is the
toroidal surface float and tower.
In the winter, Lake Michigan may be partially or completely
covered with ice. low temperatures and freezing spray would soon
render wind recording instruments useless, and it seems best to dis-
pense with the surface float entirely. The winter stations consist
of a single anchor and a subsurface float with current meters and
temperature recorders connected with braided polypropylene line.
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-11 -
Slide 12
Attached to the top of the subsurface float would be a recovery
buoy (Slide), which consists of a float, a mast with a pennant, and an
instrument case housing a release mechanism operated by either of the
• independent clocks.
Slide 13
The internal mechanism (Slide) can be preset to trigger a firing
circuit at any desired time within the next year] the circuit fires a
gunpowder squib, moving a piston which releases the recovery buoy from
the subsurface float. The buoyancy on the recovery buoy float brings
the float to the surface where it can be seen and recovered by a ship.
The recovery buoy is still connected to the subsurface float by enough
line to allow it to reach the surface.
Slide Ik
This slide shows the recovery buoy surfacing.
Slide 15
The last slide shows the recovery buoy floating naturally in
the water.
% The float is designed to accommodate a miniature transmitter
* and antenna to aid in recovery.
A high speed readout system has been developed by Information
International, Inc. utilizing a PDP-1 Computer which scans a picture
of a narrow strip of data containing film projected on the face of a
photomultiplier tube. A 100 ft. roll of film, containing approximately
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6500 observations can be read, translated into speed expressed in
cm/second,and degrees of magnetic azimuth and transferred to magnetic
tape for computer use - the entire operation requiring about ten
minutes. The development of a computer program to analyze the data and
develop wind-current relationships is in progress and should b» Avail-
able in the near future.
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