Papers Prepared in the Division of

                         Water Supply and Pollution Control, Region V

                                     For Presentation at

                 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

                                 GOALS AND THE GREAT LAKES


                                       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.


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


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

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


         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


     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.


     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


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,


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.



                        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.

          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.

       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


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


       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

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
       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


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


            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


       I would like to point out that this graphical approach to project
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.

                                                           SEARCH FOR OFFICE,
                DECISION MADE TO
                START DETROIT RIVER


TL'i 4-»-«2
TE'I 4-9-62
TL-3 4-23-62



s le

I.-IO .

n-18 ^
. 1 ..
TE- II 6-18-62
TL-24 9-t7-62

li-3 r




TE-12 6-25-62
TL- 12 6-2S- 62

TE-II I 6- 16-62
TL-12 j 6-25-62

TE-14 .


14 93
TE-19 6-13-62
TL -59 5-20-63


TL *60




•••• fr





TE* 26
TL* 66

Figure 1

Portion of PERT Program

U.S. Department of Health,
Education, and Welfare,
Public Health Service  -
Region V, Water Supply and
Pollution Control, Detroit
River-Lake Erie Project
1 t.-IB r







tt*l t







TE- 20
tt*6 |


!••• ^


TL-63 .

                                                           PERSONNEL FOR
                                                           INVENTORY ACTIVITIES
                                                           1 COMPLETED
                                                                            COORDINATED PLANNtNO
                                                                            BEGUN FOR ECONOMIC
                                                                            AND DEMOGRAPHIC
                                                                            ' STUDIES
                                          ECONOMIC A
                                         ' PEMOOR*PHI

                   COMBINED SEWER OVERFLOWS*


                     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.

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,


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

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


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.


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

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).


       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


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.


       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


       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,


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


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.


       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


       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


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


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.


       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.


       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


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


     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

sampling program which covered five months in 1961 and 1962.

       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
       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.


 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,, (.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-

         01234          — —








 01 90

 •  80

< 50

               1   I   I
         I   0   I
Before  Overflow
            After Overflow



                            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


       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,

                                 - 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

                                 - 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.

                                 - 4 -
    lower €ndfl-
                                 - 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

                                  - 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 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 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

                                 — 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

                                 - 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

                                - 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

                                - 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.

                                            -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

                                - 12 -

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.