United States
Environmental Protection
Agency
Municipal Environmental Research  EPA-600/2-80-014
Laboratory         March 1980
Cincinnati OH 45268
Research and Development
Lawrence Avenue
Underflow Sewer
System

Interim Report
Planning and
Construction

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                RESEARCH REPORTING SERIES

Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology.  Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:

      1.  Environmental  Health  Effects Research
      2.  Environmental  Protection Technology
      3.  Ecological Research
      4,  Environmental  Monitoring
      5.  Socioeconomic Environmental Studies
      6.  Scientific and Technical Assessment Reports (STAR)
      7.  Interagency Energy-Environment Research and Development     :
      8.  "Special" Reports                                           ;
      9.  Miscellaneous Reports

This report has been assigned  to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution sources to meet environmental quality standards.
 This document is available to the public through the National Technical Informa-
 tion Service, Springfield, Virginia 22161.

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                                          EPA-600/2-80-014
                                          March 1980
         LAWRENCE AVENUE UNDERFLOW SEWER SYSTEM
                                            I
                     Interim Report

                Planning and Construction   j
                           by

                      Louis Koncza
                   Donald H. Churchill
                      G. L. Miller
                     City of Chicago
                  Bureau of Engineering
                Chicago, Illinois  60610
                   Grant No. 11020 EMD
                    Project Officers

                  Clifford Risley, Jr.
          U.S. Environmental Protection Agency
                        Region V
                Chicago, Illinois  60606

                    Richard P. Traver
            Storm and Combined Sewer Section
              Wastewater Research Division
Municipal Environmental Research Laboratory (Cincinnati)
                Edison, New Jersey  08817   I
       MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
           OFFICE OF RESEARCH AND DEVELOPMENT
          U.S. ENVIRONMENTAL PROTECTION AGENCY
                 CINCINNATI, OHIO  45268

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                           DISCLAIMER

     This report has been reviewed by the Municipal Environmental
Research Laboratory, U.S. Environmental Protection Agency, and
approved for publication.  Approval does not signify that the
contents necessarily reflect the views and policies of the U.S.
Environmental Protection Agency, nor does mention of trade names
or commercial products constitute endorsement or recommendation
for use.
                               ii

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                            FOREWORD

     The Environmental Protection Agency was created because of
increasing public and government concern about the dangers of pol-
lution to the health and welfare of the American people.  Noxious
air, foul water, and spoiled land are tragic testimony to the
deterioration of our natural environment.  The complexity of that
environment and the interplay between its components require a
concentrated and integrated attack on the problem.

     Research and development is that necessary first step in
problem solution and it involves defining the problem, measuring
its impact, and searching for solutions.  The Municipal Environmental
Research Laboratory develops new and improved technology and sys-
tems for the prevention, treatment, and management of wastewater
and solid and hazardous waste pollutant discharges from municipal
and community sources, for the preservation and treatment of public
drinking water supplies, and to minimize the adverse economic,
social, health, and aesthetic effects of pollution. This publica-
tion is one of the products of that research; a most vital communi-
cations link between the researcher and the user community.
     Many of our cities are faced with pollution problems associ-
ated with combined sewer overflows.  Reduction or elimination of
combined sewer overflows into the receiving waters require some
kind of storage and treatment facilities at considerable costs,
particularly in large cities where land is scarce.  Construction
of deep rock tunnels to serve as main outlets for the combined
sanitary and storm flow offers an attractive means of minimizing
this problem.  The sewer, being below the river level, provides
storage and captures a large portion of the pollution from com-
bined sewers.  The construction cost of such a tunnel system brings
some savings as compared to conventional surface sewers, because of
the use of modern tunnel boring machines and the elimination of
surface restoration costs.  Moreover, the inconvenience to general
public by disruption of streets, utilities, sidewalks, etc. and
interference with commercial activity is completely avoided.  This
report describes the planning, design and construction of such a
deep tunnel by the City of Chicago for their Lawrence Avenue
drainage basin.


                                Francis T. Mayo
                                Director
                                Municipal Environmental
                                  Research Laboratory
                                1X1

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                            ABSTRACT

      A new and bold concept in design of urban drainage systems
was developed as a step forward in the solution of combined
sewer overflow problems.  A deep tunnel in bed rock about 200 to
250 feet  (61 to 76 m) below the surface was designed and con-
structed for the Lawrence Avenue drainage basin in Chicago.
Utilization of modern tunnel boring machines made the project
economically competitive with conventional sewers while'reaping
additional benefits of ease in construction, no disturbance to
traffic and least inconvenience to public.  In addition; the
tunnel sewer will serve as a reservoir totally capturing smaller
storms, and trapping a significant portion of the first;flush of
pollutants from larger storms.  The entrapped pollutional load
will be pumped to a treatment plant through a pumping station to
be operated only at the end of the storm, for dewatering the
tunnel.  The project is expected to reduce, to a large extent,
the combined sewer overflows to the waterways.

      Hydraulic model studies were conducted at the St. Anthony
Falls Hydraulic Laboratory, Minneapolis, Minnesota, for the
design of dropshafts to convey wet weather flows from surface
sewers to the deep tunnel.

      Pre-construction field measurements on the quantity and
quality of combined sewer overflows have already been collected
for a number of storms for 3 outfalls serving the Lawrence
Avenue drainage basin.  Similar measurements will be taken after
the tunnel is in complete operation.  Comparison of the results
will be documented in a final report to demonstrate the
effectiveness of this concept in reducing pollution to waterways
from combined sewer overflows.

      This report is submitted in partial fulfillment of
Demonstration Grant No. 11020 EMD sponsorship of the
U.S. Environmental Protection Agency.
                              IV

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                            CONTENTS           |







Foreword

                                               '


Abstract                .   . •  •                 ,.




List of Figures    .         ,                   ;




Acknowledgements                     .   .




Sections


                                               I


I      Conclusions




II     Recommendations

                                        .
                                               i

III    Introduction




         The History of Tunneling in Chicago   !    »

         Started With Water Tunnels




         Stormwater




         The Intercepting Sewer System       :. ,.




         The Chicago Underflow Plan         .




IV     Lawrence Avenue Underflow Sewer System




         General Description               .    t




         Computer Studies




         Summary of the Lawrence Avenue Sewer System




         Federal Grant (EPA Grant No.  11020 EMD)
Page




 iii



  iv




 vii
   1




   3




   4




   4






   6




   7




   8




 12




 12




 20




 25




 26

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Preparation of Contract Documents

Construction Progress

  Contract No. 1
  Monitoring Wells
  Contract No. 2
    Contract No. 2-A
    Contract No. 2-B
  Contract No. 3
  Contract No. 4

Lawrence Avenue Testing Demonstration

Relationship of the Lawrence Underflow System
to the Tunnel and Reservoir Plan
Tunnel and Reservoir Plan
for the Chicagoland Area

  Description
  Present Award Program
Page

  26

  27

  27
  43
  44
  44
  47
  61
  70

  70


 -71


  72

  72
  75
                     VI

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                           LIST OF FIGURES
Number

III-l

III-2

III-3

IV-1

IV-2


IV-3


IV-4

IV-5



IV-6

IV-7

IV-8

IV-9

IV-10

IV-11

IV-12

IV-13
                                                   Page

Existing Water Tunnels Constructed in Rock            5

Flood and Pollution Problems                          9

Flood and Pollution Control                          10

Proposed Eastwood-Wilson Sewer System Location Map   13

                                                     14
Plan and Profile of Proposed Eastwood-Wilson
Sewer System

Lawrence Avenue Underflow Sewer System Location
Plan and Profile

Geologic Profile in Project Vicinity

Performance Comparison Table of Computer
Calculation Summary for Lawrence Underflow
vs Existing Conventional Sewers
                                                     18
                                                     19
Main Shaft

Tail Tunnel

Mining Machine

Cutter Head of Mining Machine

Control Section of.Mining Machine

Head Frame                             >              34

Machine Bored Section                                38

Forms for 15'-6%"xl9'-5"(4.7mx5.9p) Concrete Lining  40
24

29

30

31

32

33
                              Vll

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Number                                                       Page
IV-14    Concrete Invert Finishing of Lining             .      41

IV-15    Finished 15'-6h"xl9'-5"  (4.7 m x 5.9 m) Section,      42

IV-16    Overall View - Model                                  50

IV-17    Exit Conduit Q = 300 cfs  (8.5 m3/sec),          ;
         TW = 10 ft.(3m)                                      51

IV-18    Exit Conduit, Q = 300 cfs  (8.5 m3/sec),
         TW = 100 ft. (30.5 m)                                  52

IV-19    Exit Conduit, Q = 600 cfs  (17 m3/sec),
         TW = 10 ft.(3 m)                                l      53

IV-20    Exit Conduit, Q = 600 cfs  (17 m3/sec),
         TW = 50 ft. (15.2 m)                                   54

IV-21    Exit Conduit, Q = 600 cfs  (17 m3/sec),
         TW = 100 ft.(30.5 m)                            ,55

IV-22    Exit Conduit, Q = 600' cfs  (17 m3/sec),
         TW = .190 ft. (58 m)                                    56

IV-23    Vertical Shaft, Q = 600 cfs  (17 m3/sec),
         Effect of Air Slots                                   57

IV-24    Entrance Conduit, Q = 300 cfs (8.5 m3/sec),     ;
         TW = 225 ft.(68.6 m)                                  58

IV-25    Entrance Conduit, Q = 600 cfs (17 m3/sec),      ;
         TW = 190 ft.(58 m)                                    59

IV-26    Entrance Conduit, Q = 600 cfs (17 m3/sec),
         TW = 225 ft. (68.6 m)                                  60

IV-27    Down Drill Rig for Drop Shaft                         62

IV-28    Close Up View of Down Drill Cutter Head               63

IV-29    Cutting Through Overburden at Drop Shaft              64 '

IV-30    Down View of Drop Shaft Excavation                    65

IV-31    Erecting Forms for Drop Shaft Boot                    66
                              vzn

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Number




IV-32    Main Shaft Lining




IV-33    KSB Submersible Pump




V-l      Tunnel and Reservoir Plan
Page




  67




  68




  73
                               IX

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                          ACKNOWLEDGEMENTS

      Acknowledgements  are given  to Harza Engineering Company of
Chicago,  Illinois, with special mention to Dr. David S. Louie,
the Chief Hydraulic Engineer and  Mr. W. T. Bristow, the Project
Manager,  for all the consultation work done  in connection with
the design of the Lawrence Avenue Underflow  Sewer System.

      Special thanks are given to the late Professor Alvin G.
Anderson, then Director of the St. Anthony Falls Hydraulic Lab-
oratory,  Minneapolis, Minnesota,  for his contributions and sug-
gestions  during the hydraulic model studies  for the dropshafts.
The assistance given by Mr.' Warren Q. Dahlin, Supervisor of the
model testing program at the Laboratory, was greatly appreciated.

      Further thanks are given to Mr. Clifford Risley, Jr.,
Office of Research and  Development, Region V, Mr. Richard Field,
Chief, and Mr. Richard  P. Traver, Staff Engineer, Storm & Com-
bined Sewer Section, all of the U.S. Environmental Protection
Agency, for their cooperation and assistance.

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                            SECTION I
                           CONCLUSIONS

1. In planning new sewers for relief of existing sewer systems
   in large metropolitan areas served by combined sewers, due
   consideration should be given to utilize the storage in the
   sewer system, either by lowering the sewer profile below the
   level of receiving waters, or by some other means.  This
   could greatly reduce spilling of pollution to ;the receiving
   waters by cutting down combined sewer overflows.

2. With the recently improved technology in the field of tunnel-
   ing, a rock tunnel sewer, while being cost-competitive,
   promises certain advantages over a large conventional open-
   cut sewer.  The former involves little interference with
   traffic, parking and commercial activity, least inconvenience
   to public, no hazards of  accidental disruption-of the
   numerous utility lines found in large cities and no costs of
   surface restoration.

3. Drilled tunnels utilizing rock boring machines  (moles) are
   relatively smooth and need not be  lined with concrete, if the
   rock is structurally sound and impermeable to exfiltration of
   polluted water into the aquifer.   This would result in savings
   in  lining costs and also  add to the tunnel storeige.

4. The air entraining dropshaft of the Type E-15, used for the
   Lawrence Avenue System, was found  satisfactory through hydrau-
   lic model testing performed at the St. Anthony Falls  Hydraulic
   Laboratory,  Minneapolis,  Minnesota, for the purpose of drop-
   ping wet weather flows  some 200 to 250 feet  (61 to 76 m)  from
   high level  sewers to the  deep tunnel.  However, the sloping
   crown  of the air collection chamber requires huge excavations
   with associated high costs, particularly  for  larger dropshafts
   than those built for the  Lawrence  Avenue Underflow Sewer
   System.  Consideration  should be given to  reduce  the  size of
   the air  chamber by venting air through a  separate shaft
   wherever feasible.   This  was indicated by  tests carried out

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later at the St. Anthony Falls Hydraulic Laboratory in con-
junction with development of dropshafts larger than 9 feet
(2.75 m) diameter for the Tunnel and Reservoir Plan for the
Metropolitan Sanitary District of Greater Chicago.

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                           SECTION II

                         RECOMMENDATIONS

As a result of construction problems encountered in the field and
additional hydraulic model studies undertaken in conjunction with
our work with the Sanitary District, several recommendations for
future "Underflow" sewers can be made as follows:

  1. Specifications should require the use of a mole within all
     practical size ranges.

  2. The drop shaft structures and the pumping station and out-
     fall should be included in the  same contract as the rock
     tunnel construction.  This would give additional shafts for
     ingress and egress, and thus, increase safety provisions. It
     would give the Contractor a greater number of  locations
     where muck could be removed and would eliminate the inter-
     ference of one Contractor with  another.

   3. The drop shaft structures should be simplified.

     a. Provide for slip forming  shafts  from top  to bottom and
        thereby eliminate  transition from  inlet jinto circular
        barrel.                                 !
     b. Reduce  the size of the air  collector at the bottom of
        •the  shaft.  In this area, consideration should be  given
         to providing  an additional  smaller diameter shaft  for
         air  release.

   4. A scale model of the  pumping station  and outfall  should be
      provided by the  designers as a check  of the feasibility of
      the design features  (and thus reduce  the possibility of
      construction problems) and as an aid to prospective bidders.
   5  The Contractor should be required to keep the floor of the
      tunnel cleared of muck and debris.  Also, a better drainage
      system in the tunnel should be required.  3Cn this tunnel,
      walking any great distance was extremely difficult because
      of poor housekeeping.

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                             SECTION III

                            INTRODUCTION

 THE HISTORY  OF TUNNELING IN CHICAGO STARTED WTTH WATER

      Chicago's first water tunnel was  placed in service in
 March, 1867.  The 5 foot (1.5 m) diameter brick, tunnel, built in
 clay, about  60 feet  (18.3  m) below  lake level, and extending
 about 2 miles  (3.2 km) into the lake to the Two Mile Crib intake
 was designed to supply Lake Michigan water to the City's first
 pumping station.  it was considered a  daring engineering project
 for its time and brought international fame to the City of
 Chicago.                                              *

      As the City grew and its water works system expanded,
 ^n1^0??1 fc^nelS Were built to new Piping stations.  However,
 many difficulties were experienced due to the poor soil condi-
 tions encountered.  in an attempt to eliminate the hazards in-
 volved,  City engineers resolved that, wherever feasible,  future
 tunnels  would be constructed in rock.

      The first tunnel built in rock was the  Southwest Lake and
 Land Tunnel,  started in 1906 and completed in  1911   see
  A?1^  J11"1:   ThS depth varied from 102  feet (31 m)  to 148 feet
 (45 m)  for  the  land portion;  the remainder was  160 feet (49 m)
below lake  level.                                             ;

      Mining in  as  many  as  six drifts was  carried  on simultane-
ously and progress varied  in  each.   For the 14  foot (4  3 m)
section the peak performance  rate recorded by any one heading
was 416 feet  (127  m) in one month.                      «wng

     The standard  method of top heading and bench was used  in
the raining operation.   Blasting techniques  left a lot to be
desired with large areas of overbreak occurring,  and conversely,
considerable trimming was also required to permit construction
of the desired section.  The specified minimum thickness 6f the

    r?VinJ£g T?V2  ^ (3°-5 Cm)' 9 inch (23 cm>  and:?
    cm)  for the 14 foot  (4.3 m), 12 foot  (3.7 m) and 9 foot

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  (2.7 m) tunnels  respectively, and as much as 1,114 lineal feet
  (340 m) of the 14 foot  (4.3 m) tunnel was lined in a month and
 almost double that footage was obtained in the two smaller size
 tunnels.

       In mining the lake section of the tunnel, some stretches
 of water-bearing rock were encountered.  Our records do not in-
 dicate what supports, if any, were required, but progress in one
 drift dropped as low as 4 feet (1.2 m) mined in one month.
 Water bled through the concrete lining and attempts at plaster-
 ing the lining were in some cases almost futile.

       As an example of the construction costs prevailing at that
 time, the contract bid price for the 14 foot (4.3 m)  tunnel,
 complete with lining, was $79.00 per lineal foot  ($260 per meter).

       Today,  there are 65 miles (104.6 km)  of water tunnels in
 service,  or available for service,  and of these,57 miles (92  km)
 were constructed in rock.  They vary in size  from 9 foot (2.7 m)
 to 20 foot (6.1 m),  most of them are in the 12 to 16  foot
 (3.6 to 4.9 m)  range.
 STORMWATER.

       Modern sanitary engineering in Chicago began with!a cloud-
 burst that dumped six inches (15.2 cm)  of rain during a 24-hour
 period August 2-3,  1885.   At the storm's end,  according;to con-
 temporary accounts,  the lake for miles  off shore  was "an
 immense foul mass of wastes  teeming with virulent bacteria."

       The 1885  storm flushed pollution  into the lake at'a rate
 affecting the area to the  water  intakes.                •

       In those  days  before chlorination,  the result was an
 epidemic of cholera,  typhoid and dysentery which  proved fatal
 to numerous victims.

      A few days  after the storm,  a plan was drawn to protect
 the health  of Chicago inhabitants  by reversing  the flow of the
Chicago  and Calumet  rivers away  from Lake  Michigan and  into the
Des Plaines  River.

      The Sanitary and Ship Canal was completed in 1900 and
hailed as an  engineering wonder  of  the world.

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THE INTERCEPTING SEWER SYSTEM

      The next step in the gigantic sanitation program involved
sealing off all wastes from Lake Michigan; it was accomplished
by constructing huge intercepting sewers 6 to 27 feet  (1.8 to
8.2 m) in diameter.  The intercepting sewers were linked to the
City's system of collecting sewers.  By 1907 the basic system
had been completed and Chicago became the first Great Lakes city
to stop using the lakes as a receptor of it's normal domestic
sewage.                                         '•
                                                I
      Because sanitation is a problem which extends beyond city
limits, the Metropolitan Sanitary District of Greater Chicago
(MSDGC) was established in 1889.  The District was to provide
for the collection and disposal of sewage from Chicago proper
and the surrounding area and to prevent flooding by polluted
water.  Today the District serves an area of 860 square miles
(2,227 sq. kms), 5,500,000 residents, and an industrial waste
load equivalent to 4,500,000 persons.

      When the Metropolitan Sanitary District grew by later
annexations, other intercepting sewers were built along the lake
shore.  The North Shore Channel was built to bring fresh water
from the lake at suburban Wilmette into the North Branch of the
river.  The total cost of the construction of the canals, sewers,
locks, pumping stations and associated works of this drainage
system was $125,091,977.

      But, while improved waste treatment methods could deal
with predictable problems, cloudbursts and flooding still re-
mained.                                         I

      The city's growth and multiplication of captured rainwater
volume long since have exceeded the sewer system's capacity.  On
an average of 100 times a year, combined sanitary and storm
water sewers overflow and surge into the rivers at 640 different
points.  Sometimes a mixture of stormwater  and 'sewage backs up
into thousands of basements.  Twenty-one times in 30 years,
flood gates of the Chicago and Calumet rivers have been opened
to keep them from going over their banks.

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 THE CHICAGO UNDERFLOW PLAN

      Recognizing the existence of many possible solutions to the
 problems of flood control and water pollution abatement,  offi-
 cials of the State, the County; the Metropolitan Sanitary Dis-
 trict of Greater Chicago, and the City of Chicago formed a Flood
 Control Coordinating Committee.

      After a thorough search of records and extensive investi-
 gation, twenty-three separate alternatives were identified for
 study.  The system recommended was a composite of the several
 Underflow Plan Alternatives and was outstanding in its relative
 storage economy and simplicity and it was originally decided
 that this system will include 120 miles (193 km)  of tunnels
 drilled principally through Silurian dolomite rock 150-300 feet
 (45.7-91.4 m)  below the city's streets.  The tunneling will be
 done underneath the rivers and the streets of the metropolis,
 thus avoiding the costs of acquiring new and expensive rights-
 of-way.  Dropshafts leading to the tunnels will intercept the
 flow in 5,000  miles (8,045 km)  of sewers before it can reach the
 640 overflow points that now line the metropolitan river-canal
 complex.   The  tunnels will be drained by pumps associated with
 three storage  reservoirs,  by far the largest, of which will be  a
 rock quarry 300 to 330 feet (91.4 to 100.6 m)  deep.   At maximum
 performance the quarry will hold a 200 foot (61 m)  depth  of
 water with a surface area 1,000 feet (305  m)  wide and 2%:miles
 (4  km)  long.   To prevent odors,  aerating pumps will continually
 agitate the wastewater prior to its  being rationed out to sewage
 treatment plants.  During these  waiting periods, solids will
 settle to the  quarry bottom and from time  to  time  will be removed
 for use as fertilizer.   This primary containing basin will be
 linked to the  two smaller reservoirs,  one  of which is to  be re-
 served for use only during the  rare  periods'when downpours com-
 parable to those experienced in the  few peak hours  of the worst
 rainstorm in Chicago's history  may strain  the  system's  capacity.
                      *r
      The  tunnel  and reservoir system will be a  genuine  flood con-
 trol project as  are  the more  customary  dams and levees built by
 the  Corps.  For  the  tunnel  and  reservoir system would do•more
 than eliminate both high flow velocity  and low water  levels in
 the  Sanitary and Ship Canal; by breaking the force of a rainstorm
 capturing the total rainfall, and later  slowly releasing the
water at  a steady rate, the system would level out the canal
 flow while increasing the average water depth. See Figures III-2
 and  III-3.
                               8

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             FLOOD AND  POLLUTION PROB!.iJV4$
                                                    DRY WEATHER
                                                    CONDITION
           Figure III-2  Flood and Pollution Problems

Diagrammatic illustration of the present conditions: Dry
Weather Condition - All dry weather flow is diverted into
the interceptor sewer, and from there to an MSDGC sewage
treatment plant.  Average Rainfall - Some overflow is
discharged into the waterway (river or canal), but the
level is not high enough to affect basements or underpasses
Heavy Rainfall - The water level rises to a point where the
hydraulic gradient reaches high enough to flood basements
and depressed areas of the city.

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                FLOOD AND POLLUTION CONTROL
                INTERCEPTOR
                   SEWER
             (To Treatment Plant)
          Figure  III-3   Flood and Pollution Control

Diagrammatic  illustration of the conditions after the "Tunnel
and Reservoir Plan"  is  implemented:  The water level is
controlled by TARP during heavy rainfalls, overflow of
combined sewage rarely  discharges into the waterways and,
the hydraulic gradient  during heavy rainfalls does not affect
basements and depressed areas.   The heavy rainfall gradient
is indicated  to show conditions before TARP.
                              10

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Completion of the Tunnel and Reservoir Plan is essential to the
success of the late Mayor Richard J. Daley's "Chicago 21" scheme
to stop deterioration of the central city and generate a vital
new life style for the next century.  The scheme covers only
eleven square miles  (28.5 sq. km)with a population of 165,000.
But in this 5 percent of its area is one-third of the total
valuation of the City's assessed property and 43 percent of all
jobs available in the metropolitan area.  By cleaning up the
waterways that traverse the city, the Tunnel and Reservoir Plan
will facilitate "Chicago 21's" intent to beautify the Chicago
River environs so as to rival those of the Thames in London, the
Seine in Paris, and the Arno in Florence.
                                                 I
      MSDGC can use its own bonding authority to obtain part of
the financing for the Tunnel and Reservoir Plan.  Another part
can come from other bonds already approved by the State of
Illinois.  But Federal appropriations guidelines set up in the
1972 amendments to the Clean Water Act of 1968 are clearly
applicable to the Tunnel and Reservoir Plan.  By the year 1983,
the United States Environmental Protection Agency is charged
with providing for the purification of all the nation's waterways
to a degree that will encourage not only sailing, boating and
fishing but also swimming.  MSDGCs analyses show that the Tunnel
and Reservoir Plan is the most reasonable and economical way to
meet the EPA requirements.  The plan will benefit much more than
a single, lake, albeit one of the Great Lakes.  The ability to
treat all, rather than only part of its sewage will enable any
city now discharging sewage effluent into rivers or lakes within
its boundaries to completely renovate its inner core.
                                                              •
      The Lawrence Avenue Tunnel was the first section of the
Chicago deep tunnel to be constructed/and as such will be
described in detail in this report.
                                11

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                            SECTION IV
               LAWRENCE AVENUE UNDERFLOW SEWER SYSTEM
 GENERAL DESCRIPTION

 Under  the  City of Chicago's Auxiliary  Outlet  Sewer  Programs,
 started in 1947,  more  than 230 miles  (370 km) of new large
 sewers have been  constructed or  are under contract  at a total
 cost of $203,000,000.   The passage of  the Sewer Bond Referendum
 of July 7,  1977 will add  another 23 miles  (37 km) of sewers to
 be constructed at a cost  of $30,000,000.  The remainder of the
 City's present Five Year  Capital Improvements Program provides
 for the construction of an additional  $116,000,000  of new
 outlet sewers.  When these sewers have been constructed all
 community  areas in the  City will have  received benefit.

 In 1963, the City of Chicago's Five Year Capital Improvements
 Program called for the  construction of a new Auxiliary Outlet
 Sewer  System to provide relief from basement and underpass
 flooding of an area bounded by the North Branch of  the Chicago
 River,  Irving  Park Road,  Oriole  Avenue and Devon Avenue.  See
 Figure  IV-1.   Preliminary hydraulic studies indicated that a
 new trunk  sewer in the  vicinity  of Wilson Avenue from the North
 Branch  of the Chicago River to Melvina Avenue with branches
 extending north and south to intercept existing trunk sewers,
would provide the  necessary flood relief.

This proposed sewer system was designated the Eastwood-Wilson
Avenue  Sewer System and varied in size from a 2 barrel 13 ft.
 (3.96 m) by 13  ft.  (3.96 m)  section at the lower end near the
River to a 7.5  ft.  (2.29 m)  circular section at its upper end.
This sewer was proposed to be built in five contracts,  by
conventional methods,  four by open cut construction and one by
earth tunnel under the Edens and Kennedy Expressways.   See
Plan and Profile,  Figure IV-2.
                               12

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13

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 Some measure of reduction in pollution,  caused by the overflow
 from combined sewers to the river,  is provided by depressing
 the outlet of the conventional auxiliary outlet siewers below
 river level.  The resulting storage thus produced is sufficient
 to contain the runoff from frequently occurring small rainfalls
 and thus preventing overflows to the river.   The Eastwood-Wilson
 Avenue sewer system would have equivalent storage volume below
 low river water level of 0.07 inches (0.18 cm)  spread over its
 3620 acre (14.6xlObnT)  direct tributary  drainage area.  This
 would be equal to the runoff from a mass rainfall of approxi-
 mately one quarter of an inch (0.63 cm)  over this! entire area.
                                                  I
 Because pollution abatement was of  major concern .to engineers in
 this field,  consideration was given to lowering the profile to
 increase the pool storage available in the downstream end of the
 sewer and thereby reduce the frequency of overflows from this
 combined sewer to the river.  Lowering the profile would necessi-
 tate pumping of sewage  to the existing sanitary intercepting
 sewer,  increasing the overall cost.   it  would also require that
 more of the  construction be performed by earth  tunnel method.
 Recent development of earth mining  machines  has resulted in
 lower bid prices in earth tunnel contracts.   However,  preliminary
 soil investigations indicated that  heavy primary steel lining
 and occasional rock sections would  negate the savings from the
 use of such  machines.   Costs would  greatly exceed; that of the
 conventional open cut construction  method.
                                                  I
                                                  j
 The City of  Chicago had obtained previous experience  in building
 large water  tunnels in  rock at an elevation  of  100 feet (30.5  m)
 to  200 feet  (61  m)  below the surface,  i.e.,  the 6  mile  tunnel
 under Lake Michigan from the Central  District Filtration  Plant
 to  Wilson Avenue,  a 4.6  mile (7.4 km)  tunnel  in 79th  Street, and
 the 3  mile  (4.8  km)  tunnel  in Columbus Avenue.   These  tunnels
 ranging in size  from 12  feet (3.6 m)  to  16 feet (4.9 m) were
 constructed by the  conventional  drill  and blast method.
                                                  I
                                                  I
Recent  improvements  of the  rock mining machines  (Moles) had
 reduced the  cost  of  tunneling in  various kinds  of  rock materials
 for large irrigation  and hydroelectric projects  throughout the
world.   Preliminary cost estimates revealed that mining in rock
might be  competitive with open cut methods.

Lowering  the profile of  the Eastwood-Wilson sewer over one
hundred  feet into bed rock  looked promising.   Sanitary flow
would not normally, in dry weather periods, enter the tunnel
                                                  I
                                                  I
                               15

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and therefore would not be pumped on a continuous basis.  Pump-
ing would be required, however, for dewatering of the tunnel to
the existing sanitary intercepting sewer in the post rainfall
period.

The City of Chicago's Department of Public Works retained the
services of a consulting engineering firm, Harza Engineering
Company, to study alternate methods of constructing the proposed
Eastwood-Wilson Auxiliary Outlet Sewer System.  The studies
included a comparison of costs of constructing the sewer by open
cut and tunnels, the hydraulic feasibility of the system, the
maintenance and operating costs, and recommendations on the best
method to fit the City's needs.

Beginning November 1, 1966 the sewer project known as EASTWOOD-
WILSON was re-designated as the LAWRENCE AVENUE SYSTEM with
subsequent contracts prepared by the Harza Engineering,Company.
The principal sewer,  Contract No. 1, was designed and built in
deep tunnel as recommended in the appraisal repprt prepared by
said firm.

A review of geologic data indicated that, along the proposed
route of the rock tunnel, the stratigraphic sequence would start
with an overburden of glacial drift varying in thickness of
Niagaran-Alexandrian rock lying above a formation of Maquoketa
shale.  It was the Niagaran-Alexandrian rock strata which
warranted more information.  Thirteen borings were taken along
the route to a depth exceeding 250 feet  (76 m).  The analysis of
these borings was studied with three elevation ranges in mind.
The upper range contained interbedded cherty and shaly dolomite
with some zones of reef material.  If built in this range, the
tunnel would be located within 40 to 50 feet  (12 to 15 m) of
depressions in the bedrock surface which was known to be
locally broken and fractured.  It was thought that clay-filled
crevasses might be present as had been observed at quarries in
the Chicago region and as encountered in water tunnel rock
mining in nearby Wilson Avenue.  Also, the weathered rock
occurring at the top of bedrock contained open joints and
solution channels and was known to be a high-yielding ground-
water aquifer.

If the tunnel were constructed in the middle range, it would
pass predominately through a porous dolomite believed to have
originated as a coral reef.  "Driliability" tests of typical
core samples taken from the Lawrence Avenue borings brought
forth an opinion that the reef dolomite had a drillability of
                               16

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 about  25% less  than  the  other  types  of  roclc tested.

 The  rock  in  the lower range was  found to be principally  shaly  '
 dolomitic limestone  with strengths varying  roughly from  10,000
 to 30,000 psi  (7xl06 to  21xl06 kgs/sq m), with  the majority of
 the  readings spread  between 19,000 and  23,000 psi  (13.4xl06 and
 16o2xl06  kgs/sq m).  The rock  at this lower level also presented
 a uniformity of strata and was relatively free  from  interbeds.
                                                 I
 These  geologic  characteristics,  which are only  stated in general
 terms, were  then related to costs and construction problems that
 might  be  inherent  to each level.  Obviously, the more shallow
 the  tunnel,  the greater  the savings  in  shaft construction costs
 and  pumping  requirements, both in original  cost of the pumping
 units  and their operation.  However,  the porosity of the upper
 level  rock,  with clay-filled crevasses  and  the  possibility of
 fractured rock  zones could result in costly and hazardous con-
 struction with  the need  for steel roof  supports, as  well as rock
 bolts  and wire  mesh, and would require  that a substantial con-
 crete  lining be installed,.  Because  of  the  negative  features of
 the  higher level rock zone plus  the  necessity of crossing a
 water  tunnel located in  the same  stratum, it was decided to
 locate the tunnel at a depth ranging from 250 feet (76 in) to
 220  feet  (67 m)  below the surface.   It  was  also believed that,
 with the  dense,  uniform  dolomite  to  be  found at the  accepted
 level, any possibility of polluting  the aquifer would be elimin-
 ated and  that as construction proceeded, evidence! would be
 gathered  and a  determination made on the possibility that, where
 mining was performed by machine, no  lining would be  required, or
 at the most, a  very  thin  lining  for  hydraulic reasons.

Where drill  and blast methods were used for  rock iexcavation, an
 8-inch (20.3 cm) minimum  lining was  specified because of the
 irregular  surfaces typical of this procedure.
                                                 j
                                                 I
Harza's appraisal report  recommended the construction of a lined
 tunnel sewer in the Niagaran limestone  formation japproximately
 250  feet  (76 m)  under the surface of Lawrence Avenue.  See
Figures IV-3 and IV-4.  The rock tunnel would be excavated by a
 tunnel boring machine.  The Lawrence Avenue route was selected
because of the  requirement of the mole to travel in nearly a
 straight line.    Because the tunneling would be  so far below the
surface,  traffic in that arterial street and commercial activ-
ities would not be interrupted, as would be the case with the
conventional open cut construction.
                               17

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       UNDERFLOW    PLAN
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          ••••HIOH-LEVEL FEEDER LINES
                          CITY OF CHICAGO
  LAWRENCE  AVENUE

  UNDERFLOW  TRIBUTARY

Figure IV-3 Lawrence Avenue Underflow Sewer System
             Location Plan and Profile
                 18

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The main tunnel would be 12,800 feet  (3091 m) long at 12 feet
 (3.7 m) in diameter and 9,300 feet  (2835 m) long at 17. feet
 (5.2 m) in diameter.  A branch tunnel in Harding Avenue extend-
ing, south from Lawrence Avenue to Berteau Avenue, a distance of
4,000 feet  (1219 m)  (formerly a new conventional branch line,
later lowered to be a rock tunnel) would also be 12 feet  (3.6 m)
in diameter.  Approximately 18,000 feet  (5486 m) of new
conventional branch sewers would relieve the overloaded existing
sewers and convey the flow to the tunnel inlet shafts.;  Ten
inlet shafts would be constructed to  supply the tunnel: and one
30 foot diameter outlet shaft for the discharge of drainage.

The total storage in the tunnels and  shafts would be about
4,000,000 cubic feet  (113,280 m3) or  about 0.30 of an inch
 (0.8 cm) over the 3,620 acre  (14.6xl06m) drainage area.  This
 storage would provide space for the runoff from rainfall
 accumulation up to about 0.9 inches  (2.3 cm) without overflowing
 to the river.

 The cost of the tunnels, shafts, high level collecting branch
 sewers, pumping and ventilation facilities and the gate and
 outfall structures was estimated at $12,334,000.  This was
 $2,000,000  less than the estimated  $14,350,000 cost of the
 conventional open cut method of construction.  These estimates
 were prepared in 1966.  The Engineering News Record, Construc-
 tion Cost Index at that time was about:  ca 1019.

 COMPUTER STUDIES

 In order to analyze  the Lawrence Avenue Underflow sewer system
 under  actual operating conditions,  a  mathematical model of the
 system was  simulated in a  computer  program developed by the  City
 of Chicago's Bureau  of Engineering.  Each  hour of rainfall
 during an entire year was  analyzed.  The amount  of rainfall
 along  with  the corresponding hourly code was recorded  on
 punched cards.  The  computer was programmed  to  determine  the net
 runoff from the impervious and pervious areas  for each hour  of
 rainfall.   For the impervious  area, a small  amount of Depression
 storage was subtracted  from the first hours  of  rainfall of each
 storm to obtain the  net runoff supply.   On pervious  areas,
 depression  storage and varying amounts  of  infiltration depending
 on wet or  dry antecedent  conditions were subtracted  from  the
 rainfall  to determine the net runoff  supply.  The total runoff
 was  then  calculated by weighing the net runoff supply  from the
 impervious  and the pervious areas in accordance with the
 imperviousness  ratio of the tributary drainage  area.

                                20

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A hydrograph with a mass equal to the net runoff ssup>ply was then
developed.  The base of this hydrograph can be caairied for the
time of concentration of the tributary sewer system.  The hydro-
graphs for adjacent hour periods having a net runoff supply
were then added together, somewhat similar to the method used in
summing the unit hydrographs in river hydrology„

Sanitary flow at a rate of 100 gallons  (378.5 liters) per day
per capita was added to these runoff hydrographs* to obtain the
combined flow hydrographs for every rainfall period of the year.
For this study 0.01 cubic feet per second per acre  (7.07xlO~4
cubic meter per second per hectare) was used as the sanitary
flow rate.  This rate has been verified as a good approximation
for the quantity of sanitary flow by the U»S. Public: Health
Service studies on the Roscoe Street sewer system.
                                                 I

At each overflow point of the existing sewer system, it was
assumed that up to two times the dry weather flow would continue
to flow by the overflow weir and along its present route to the
treatment plant.  The excess flow over and above two times the
dry weather flow overflows down into the tunnel  system.

The sanitary flow at these overflow points is assumed to be
uniformly mixed in the total combined flow upstream of the
controlling weir.  Four  assumptions were set for the pollutional
load in the combined flow.  These were as follows!:
                                                 l      •>

     1. Suspended Solids in Sanitary Sewage =    j  114 mg/1
     2. Suspended Solids in Stormwater Runoff  =  227 mg/1
     3. B.O.D. in Sanitary Sewage =                  96 mg/1
     4. B.O.D. in Stormwater Runoff =                17 mg/1
                                                 i
Data for  sanitary sewage were taken from the Metropolitan
Sanitary District records of influent to the North Side Treat-
ment Works for the years 1958 and 1959.  Data for storm flow
were taken from a report of Stormwater runoff measurement by
the Public Health Service for a test drainage area in Cincinnati,
Ohio.                                            |

A graph of the storage volume was plotted against the water
surface elevation in the tunnel.  This data was  placed in the
computer  with  linear interpolation between sets  of points.  When
the volume of  inflow to  the tunnel exceeded the  total storage
volume, the excess water was discharged to the river.  Limita-
tions  were placed on the maximum discharge flowing through the
system, since  storms exceedincr the design capacity of the

                              21

-------
 existing sewer  system and the  new tunnel  system would cause
 upstream basements  to flood.   This flooding would  limit  the
 maximum discharge through the  system.  This eventuality  was
 provided for  in the computer by  flood  routing procedures and
 limiting the  maximum discharge to 1500 cfs  (42.48  m3 per second)
 to cover a  storm event with a  return period of 5 years.

 A set time  after the last hour of rainfall of a storm period,
 the dewatering  pumps were turned on.   The pumps were set at
 48 cubic feet per second  (1.36 m3 per  second) which would
 provide  complete dewatering of the tunnel to the interceptor in
 24 hours.                                             :

 The B.O.D.  in the tunnel  was assumed to be pumped  to the
 interceptor or  to overflow to  the river at the instantaneous
 concentration in the system.   The suspended solids were  divided
 into two parts,  that which would remain in suspension and that
which would settle  as a function of tunnel velocity.  That
portion  which remained in suspension was pumped during'dewater-
 ing or overflow to  the river at  the instantaneous concentration
 in the system.   The  volume of  suspended solids that settled to
 the bottom was  assumed to be removed by flushing and pumping
 after the tunnel was  dewatered,  or during large storms;when
high velocities  occurred  in the  tunnel and scouring would cause
the settled solids  to be washed  to the river.  A linear relation
between  zero  resuspension for  zero velocity to 100% resuspension
 for a velocity of 10  feet per  second (3 m per second) was used.

The type-out  of the computer program was as follows:

Column               Description of Data

  1.    Time 'in hours from beginning of year.
  2.    Rate of rainfall  for hour period.
  3.    Runoff in cubic feet per second from the drainage area.
  4.    Instantaneous elevation of water surface in tunnel.
  5 .    Volume of water in the tunnel,  in cubic  feet.
  6.    Discharge into the tunnel, in cubic feet per second.
  7-    Pumping rate to M.S.D. interceptor,  in cubic
        feet/secondo
  8.    Overflow from tunnel to river,  in cubic  feet/second.
  9.    Accumulation from first of year of suspended solids
        to tunnel,  in pounds.
                               22

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Column  (contd)
Description of Data  (cbntd)
  10   Accumulation from first of year of B.O.D. to tunnel,
       in pounds.
  11   Accumulation from first of year of suspended solids to
       river, in pounds.                          !
  12   Accumulation from first of year of B.O.D. to river, in
       pounds.                                    i
  13   Accumulation from first of year of suspended solids
       pumped, in pounds.                         j
  14   Accumulation from first of year of B^O.D. paimped,  in
       pounds.

In Columns  9  & 10, the  suspended solids  and B.O.D. overflowing
the weir to the tunnel  can be assumed to be equivalent  to the
spillage to the river of an  existing sewer system of  equivalent
drainage area.  Therefore, comparing these columns', with
Columns 11  and 12 enables the determination of  the! reduction in
suspended solids and B.O.D.  for the drainage  area with  the
Lawrence Avenue tunnel  system in place.           \
                                                  \
Table  I, see  Figure IV-5, shows the results summarized  for five
years  of records using  the rainfall as  it occurred at Midway
Airport, U.S. Weather Bureau Gage  for  1956 to 1960 inclusive.
                                23

-------




















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24

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SUMMARY OF THE LAWRENCE AVENUE SEWER SYSTEM

A chronology of events leading up to the development of the
Lawrence Avenue Sewer Plan including the appraisal report by the
Bureau of Engineering's consultant, Harza Engineering Company,
and the electronic computer studies is presented.

The appraisal report recommended the Lawrence Tunnel Sewer with
indicated savings of $2,000,000 over the conventional open cut
method while providing all of the benefits of flood protection.
It minimized street disruption during construction and resulted
in less inconvenience to residents,-pedestrians, commerical
enterprises, parking, vehicular traffic and utilities»  The
Underflow,Sewer would result in greater storage and provide for
less frequent overflows to the Chicago River.    |

The computer studies summarized in Table I indicate an average
of the five years studied of 59 overflow periods for a total of
235 -hours for the existing sewers and would be reduced to 5
overflow periods for a total of 18 hours.  This represents an
average of about 92 percent reduction in both the number of
overflow periods and the hours of overflow.  The pounds of
suspended solids and B.O.D. discharged to the river would be
reduced by 73 and 78 percent, respectively.

Studies have indicated that combined sewers spill in the neigh-
borhood of 3% of the sanitary sewage to the receiving streams
during the course of the year.  The above figures indicate that
with the Lawrence Avenue Underflow Sewer in operation, less
than 0.8% of the sanitary sewage pollutants would be discharged
to the North Branch of the Chicago River from its tributary
drainage area.  Another way of stating this is to say that over
99% of the suspended solids and B.O.D. contained in sanitary
sewage would be delivered to the treatment plant for processing
before being discharged to the waterways.

In the pumping station contract, instrumentation was to be
provided to monitor the gate openings, the level of water in  the
tunnel at all times, operation of  the dewatering|pumps and auto-
matic sampling during spillages to the river.    >

It was hoped that construction under the first contract would
demonstrate that the use of a hard rock mining machine or  "mole"
to tunnel through the hard dolomitic  limestone rock: in the
Niagaran  strata was economically feasible and woiildl provide
data  for  future sewers of this type.

                               25

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FEDERAL GRANT   (EPA Grant No. 11020 EMD)

Early in 1967,  the Department of Public Works applied for a
Federal Demonstration Grant for the Lawrence Avenue Deep Tunnel
Sewer System.   A grant offer of $1,500,000 was approved on
April 25, 1967, subject to the approval of final plans and
specifications  for the project in addition to other conditions
and assurances.

It was considered to be a demonstration grant because no city in
the nation was  currently using such a system, which would have
application in  highly developed urban areas where- space for
surface storage is uneconomical.  The portions of the project
which were eligible for grant participation, however,.were
limited to the  rock tunnel sections and the pumping facility
under Contracts No. 1 and No. 3.

PREPARATION OF  CONTRACT DOCUMENTS

Based on the findings of the appraisal report, the City's
Department of Public Works, retained Harza Engineering Company
to prepare contract documents for the Lawrence Avenue System.
The total cost  of this consulting contract was $621,142000 which
included the appraisal report,  reimbursable items,  and services
provided in the design and preparation of contract documents for
the following contracts, construction of which were required to
complete the system as planned:

    Contract No. 1 - Main Shaft and Rock Tunnels
    Lawrence Avenue Monitoring Wells
    Contract No. 2-A - High-Level Tunnels in Earth
    Contract No. 2-B - Ten Drop Shafts
    Contract No0 3 - Pumping Station and Outfall
    Contract No. 4 - Additional  High-Level Sewers               .
                               26

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COBSTRUCTION PROGRESS
                         Contract No. 1
Contractor;
Bid Price;
Financing;
Location:
Contract
Description:
     Main Shaft and Rock Tunnels

Joint venture of James McHugh Construction Company,
S.A. Healy Company, and Kenny Construction Company.
$10,792,094.00
22% of construction cost was paid from City's share
of Motor Fuel Tax Funds.  Balance from Sewer Bond
Funds, and from Federal Funds.
In Lawrence Avenue from North Branch of the Chicago
River to Melvina Avenue, and in Harding Avenue from
Lawrence Avenue to Berteau Avenue.    ;
                                      I
16,638 feet  (5,071 m) of 12'-0"  (3.66 m) diameter
and 9,126 feet  (2,782 m) of 17'-0"  (5^18 m) diameter
concrete-lined sewer tunnels in rock; excavation of
approximately 250 feet  (76.2 m) of main shaft of
29'-0"  (8.84 m) in diameter in earth, excavation and
27'-o11  (8.23 m) in diameter in rock excaivation;
surface restoration; and all appurtenant and
collateral work.
Construction
Starting
Date;
Status;
November 6, 1967
Contract completed May 28,
1973
 Construction Methods;
 As  a prebidding feature,  DPW had in February of  1967  advertised
 an  invitation notice  to inform prospective bidders; of the work
 to  be done  under this contract.  At the conference; that followed,
 and which was attended by representatives of almost fifty
 contracting,  manufacturing and supply companies,  it was indicated
 by  the City that consideration should be given to boring the rock
 tunnels by  machine if possible.

 The low bidder on this project elected to use an existing rock
 mining machine that could be made available  in a short time but
 whose^ cutting-face diameter was 13'-8" (4.17 m).   His procedure
 called for  first mining the 17-foot (5.18 m) tunne|l with this
 machine at  the correct bottom elevation and  then enlarging  to
 proper size by conventional drill and blast  methods.   By mining
                                27

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 to  the  correct bottom elevation,  trackage  for   his muck cars
 could be installed and put into use as  the heading advanced.

 The,12-foot  (3.66  m)  finished diameter  tunnel  in  Harding Avenue
 and in  Lawrence  Avenue (west of Kildare Avenue) would also be
 bored with this  machine0   Both size tunnel sections would be
 lined with a minimum  8" (20.3 cm)  concrete lining as  specified
 in  the  contract  documents 0

 The Contractor started work by excavating  the  main shaft with
 conventional methods.   See Figure .IV-6.  The top  forty1feet
 (12.2 m)  of  29 foot (8.84  m)  diameter shaft in over-burden was
 supported by steel ribs and sheeting.   The additional 215 foot
 (65.5 m)  depth of  shaft, 27'  (8.23  m) in diameter, was drilled
 and blasted  in a very  short time.   A tail  tunnel, see Figure IV-7,
 to  accommodate muck car unloadings,  was blasted for a distance of
 73  feet (22.25 m)  northeasterly from the shaft, and a 316 foot
 (96.3 m)  length  of full-size excavation for the 17-foot (5.18 m)
 tunnel  section was shot out while waiting  for  the mining machine
 to  be deliveredo

 The rock-mining  machine, see Figures IV-8, IV-9 and IV-10, was
 assembled in the tunnel and,  for  the next  two  months,  tested
 under actual operating conditions until the Contractor:was
 satisfied that limestone of the hardness of 11,400 psi  to
 29,600  psi (SxlO6  kgs/m2 to 21xl06 kgs/m2) that was expected to
be  encountered could be successfully bored by  Machine.   Several
 types of  conveyor  set-ups  were  also  tried  during this time in an
 attempt to find  an efficient way of bringing the muck  from the
cutting wheel  to the cars.   The excavated  material as cut by the
machine resembled  irregular chips of rock, no  longer than 2"
 (5.1  cm)  on  any  side.   A substantial amount of muck was  too fine
in  size to be  scooped up by the machine and had to be washed out
from  in front  of the machine  face.

The tunnel was properly ventilated as work progressed, and for
dust  control, water was, sprayed on the rock face at the heading
at  a  rate of 40 gpm (151.4  1/m).

All tunnel excavation then  stopped for 39 calendar days while
the Contractor erected his head frame and hoisting equipment,
see Figure IV-11, and performed other miscellaneous work.  At
the end of May, 1968 full  scale use of the mole began.
                               28

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29

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30

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31

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r^i^^r^"^   -"T^iC?,,^
               32

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33

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Figure IV-11  Head frame and hoisting equipment at main shaft.




                              34

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Some facts concerning major equipment items used by the
Contractor, including the mining machine particulars, follows:
Mining Machine Data
  Manufactured by:
  Thrust of Machine
  Drive of Machine No. 1
  Drive of Machine No. 2
  Operation Voltage
  Make of Bits
  Number of Cutters
  Dia. of Cutterhead:
    Machine No. 1
    Machine No. 2

  Length of Machine:
    Assembly
    Drawbar
    Power Train
    Auxiliary Power Train
    TOTAL LENGTH
  Tunnel Power Line
  Conveyor System
    Manufacturer
  Muck Cars
  Length of Train
  Track Gauge
  Locomotive s
  Ventilation
Lawrence Mfg. Co.  (Seattle,  Wash.)
1,300,000  Ib.  (589,680 kg). Maximum
5-125 hp.  motors  (126.75 hp  -  metric)
3-250 hp.  motors  (253.5 hp - metric)
480 Volts
Lawrence Mfg. Co0
29 Disc-Type with carbide  inserts
13'-8" dia,
13'-9" dia.
Lawrence
(4.16 m) |in Lawrence  Avenue
(4.19 m) in Harding and
19--11"  (6.07 m)
15'-11"  (4.85 m)
23'-7"  (7.19 m)
25'-4"  (7.72 m)
84f-9"  (25.83 m)
4,160 Volts
Lawrence Mfg. Co. with a Goodyear
Belt 24"  (61 cm) wide by 84'  (25.6 m)
long                 ;
6 Cubic Yards  (4.59 m3)
9 Cars
36-inch  (91.4 cm)
10 Ton  (9072 kg) Plymouth Diesel, 86 hp
(87.2 hp-metric)
28"  (71 cm) Vent line
2-40 hp  (40.56 hp-metric) Vent fans
made by the Joy-Axivane Co.-, 14,000
                          CFM (396 mVmin)  each
                          (15.2 hp-metric fan at street level to
                          prevent any line back pressures.
  Line & Grade Control
By Laser Beam
                               35
                        One 15 hp

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Factors Adversely Affecting Progress;

1. The basic and major problem which had delayed completion of
this contract, and the entire sewer system, had been the poor
performance of the original mole.  The machine when working
properly could mine an average of about five lineal feet; (1.5 m)
of tunnel an hour.  It was expected that the machine would be
out of operation during periods that the cutters had to be
replaced and normal maintenance performed.  Many other malfunc-
tions had to be corrected, some of them several times.  The
down-time reports include items such as bearing replacements,
replacing cutter 'guard, repairing hydraulic leaks, repairing
pilot cutter gear drive, disassembling hydraulic thrust system
and repairing drive shaft housing, repairing transformer at
Seattle plant, and many others.

The Contractor's "Critical Path Schedule" indicated an expected
average mining rate of 282 lineal feet  (86 m) per week with the
mole, based on the claims of the manufacturer.  After 49 weeks
of actual performance, the machine had averaged about 132 ft.
 (40 m) per week and was completely worn out.  The machine was
dismantled and removed from the job and, while awaiting delivery
of a new machine, the Contractor continued work by conventional
drill and blast methods.

The second machine was placed in operation December 1, 1969 in
Harding Avenue and later bored the Lawrence Avenue portion of
12-foot  (3.7 m) tunnel.  This machine bored an average of
better than 6 lineal feet  (1.8 m) per hour and, when full scale
operation could be maintained, completed as much as 426 feet
 (130 m) in one week,

2. When the first mining machine performed so poorly, the
progress of the tunnel work was definitely handicapped by the
fact that the only point of ingress and egress to the work was
through the main shaft0  This is a calculated risk with deep
tunnel work because of the high cost of excavating additional
work shafts and installing hoisting equipment.

It should be pointed out that two similar rock tunnels were
later contracted for by the Metropolitan Sanitary District
based on the information gained by our pioneering of the
Lawrence Ave. project.  Each tunnel was bored by machine from a
single shaft and completed in rapid fashion.  Each machine used
was by a different manufacturer than the ones tried on this
project.
                              36

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 3. When the Contractor enlarged the 17-foot  (5 ,.2 m) tunnel to
 full size after drilling a 13'-8"  (4.2 m) hole with the mole, he
 did not trim his blasted section to suit the steel form to be
 used in pouring the 8"  (2003 cm) concrete lining„  Later while
 the mole was excavating westerly in Lawrence Avenue, the lining
 operations could also have been going on simultaneously, but
 the muck train movements to the shaft interfered with the
 trimming of these tight spots and as a result the concrete
 lining operations stopped for nine months.
                                                I

 4. Strikes by both the operating engineers and the truck drivers
 during the life of this contract also added to the Contractor's
 problems.
 Contract Modifications;

 1. The original machine was difficult to steer and thus maintain-
 ing line and grade was a problem.  At the Contractor's request
 the finished invert grade was revised to suit the actual grade
 of tunnel as bored by the original mole for the first 6,128 feet
 (1,868 m).   The costs to revise the design of the drop shaft
 structures  because of this change were paid by the Contractor.
                                          DEDUCTION = $12,250.00

 2.  Because  of the  excellent condition of the limestone rock in
 which  the tunnel is located,  see Figure IV-12,  It had been
 decided that concrete lining of the machine-mined sections would
 not be required.   Restoration work in some areas,  consisting of
 rock bolts,  wire mesh and guniting was performed.   The
 Contractor  submitted an  acceptable proposal to  do the work.,
                 For Harding  Av.  Tunnel -  ADDITION = $19,000.00

    NOTE: By  eliminating  the concrete  lining from  these 12  ft.
          (3o7 m) tunnel  sections,  and performing  only corrective
         work as stated,  the  total savings  to the  City was  in
         excess of  800 thousand dollars.   in addition, the
         elimination  of  the lining increased the  storage
         capacity of  the  system by about 580,000 cubic feet
          (16,425 m3).                           I

3o Because of the Contractor's procedure in excavating the
original 17-foot (502 m) tunnel first by machine bore and then
enlargement by blasting, a substitute finished section was
designed.  To achieve equivalent area, an egg-shaped section
resulted, with a 7'-6" (2.3 m) crown radius and
invert radius„  The maximum inside dimensions are .15'-6%" (4.7 m)
                              37
a 6'-0" (1.8 m)

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 in width,  and 19'-5"  (5.9 m)  in height.   See figures IV-13,
 IV-14 and  IV-15o  There was no change in cost toj the City for
 this modification.

 4. Five time extensions were negotiated  and apprpved.  They  were
 for 482 days,  30 days,  120 days,  153 days and isb days.

 5. Extra to perform tunnel restoration work in the Lawrence
 Avenue portion of the machine-mined tunnel»
                                                ADDITION = $87,000
                                               ADDITION =  $17,653
60 Tunnel inlet to the main shaft.

Other Items;

1. Contract Documents;
                                         •
The length of tunnel actually excavated is less than that called
for in the proposal quantities because of the design and location
of the drop shaft structures <,  This information was not known
when this contract was prepared and actually resulted in reducing
the final cost of the contract.

The radius of the tunnel curve at Milwaukee Avenue was increased
from 180' (54.9 m) to 500' (152*4 m) to accommodate the Contrac-
tor and to suit the length of the mining machine 1
                                                 l
2o State and Federal Requirements;

Because both Motor Fuel Tax Funds and Federal Grant money were
involved, the contract documents contained the inserts and
specifications required by the agencies concerned.

3. Traffic and Safety;
The only construction shaft was located on MSDC property and
therefore maintenance of vehicular traffic was not involved.

Safety regulations were documented in the specifications and
were adhered to by the Contractor.

4o Supervision of Construction;
                                                 i
Supervision was more than adequate and the complaints regarding
noise and vibration, which were to be expected where blasting
was performed, were handled with skill and understanding.

                               39

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                                          .
i'^^Hi;^*,, ^jri,%'„'.«.!,'• js'iff L,,S  ii,*-'"^^*:;*^"/'1'- '.« i ;.^w^ '^"--^wr^."
  '   '11""   ''        '1'*"''11" !""       "           lltv"
                                40

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41

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Figure
              section
        prior
shaft and pump sump
forming transition to main
                               42

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 Recommendations;
 1. Wherever possible, rock tunnel-type sewer systems should be
 designed and constructed.  Specifications should require the use
 of a mole within all practical size ranges.
        '                                         i
 2» The drop shaft structures should be included in the contract
 with the rock tunnel construction.  This would give additional
 shafts for ingress and egress, and thus increased safety pro-
 visions, but also would provide the Contractor with a greater
 number of locations where muck could be removed.
                                                 I
 3. The Contractor should be required to keep the'floor of the
 tunnel cleaned of muck and debris.  Also a better drainage system
 in the tunnel should be required.  in this tunnel,  walking any
 great distance was extremely difficult because of poor house-
 keeping.
 Contractor;
 Bid Price;
 Financing;
 Location;
           Monitoring Wells
Wehling Well Works, Inc.
$45,805o00                          ;      .   ;
Sewer Bond Funds                    }
Just west of the southwest corner of Harding and
Wilson AvenueSo
 Description  & Purpose;
                                                 I
                                                 !
 Three wells  on 20-foot  (6.1 m) centers were  drilled  to  different
 depths with  12 3/4"  (32.4 cm) diameter casings  in1 earth and  10"
 (25.4 cm) bores  in rocko  These wells were installed so that the
 necessary data could determine if the Lawrence  Ave.  Underflow
 System has any objectionable effect on the Silurian  aquifer  and
 on the Wilson Avenue water tunnel which crosses Harding Avenue
 about 89 feet (27 m) above the sewer tunnel.  These  data consist
 of water level measurement recordings, and sampling  taken from
 each well.                                                ,   _
Contract Modifications;                          \

There^were no modifications or adjustments to final contract
quantities as the work was successfully completed without the
need to assess liquidated damages.               [

Comments;
                                                 I
A small job of this type created no traffic problems and was so
specialized that it required customized plans and j specifications..
                               43

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Results To Date:

Since completion of the contract, results have been reviewed of
water level measurements, and of the samples which have been
taken on a monthly basis by personnel from the Bureau of Water,
no adverse effect on water quality or quantity has been noted.
The same frequency is to be maintained after the sewer system is
in operation except that additional measurements and samples will
be taken the day following any storm great enough to cause
pressurization of the tunnel.

As a separate study, the wells were also tested by the Illinois
State Water Survey in order to determine horizontal and vertical
permeabilities of this aquifer.

                         Contract No. 2

    High-Level Tunnels in Earth  and Drop Shaft Structures
Problems Encountered With Contract No. 2
Bids for Contract No. 2  of this  system were  received on
October 3,  1969 but were rejected as too high because the low bid
of three received exceeded by 31.5% the estimate prepared by
Harza  Company.  The contract  in  part called  for the ten drop
shaft  structures to be constructed without disturbing the work
being  performed in the rock tunnel and making connections to  the
completed  tunnel  later.
The work originally proposed  under Contract  No. 2 was then  split
 into two contracts by the City's Department  of  Public Works with
construction of the  drop shaft structures  to be delayed until
 after  the  rock tunnel excavation was completed.   This would be
Contract 2-B.  The balance  of the proposed work was put  into
 Contract 2-A and re-bid. The wisdom of  this procedure was  proven
when the low bids for 2-A and 2-B  combined totaled $389,305.00
 less than the original  No.  2  bid.

                         Contract NQo  2-A
                    Hiqh-Level Tunnels  in Earth
 Contractor;   Reliance Underground Construction Company,  Inc.
 Bid Price;    $2,393,645.00
 Financing;    52% of construction cost paid from City's share
               of Motor Fuel Tax Funds.  Balance from Sewer
               Bond Funds.
                                44

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 Location;
 Contract
 Description;
 Estimated Cost
 of Revising
 City-Owned
 Utilities;

 Construction
 Starting
 Date;

 Status;
 In Menard Avenue from Lawrence Avenue to Berteau
 Avenue; in Melvina Avenue from Lawrence Avenue to
 Gunnison Street; in Moody'Avenue from Gunnison
 Street to Strong Street to Mobile Avenue to
 Foster Avenue;  and in Argyle Street from Mobile
 Avenue to Nagle Avenue.

 700 feet (213 m) of 5'-0" (1.5 m)  diameter, 1,310
 feet (399 m)  of 6'-0" (1.8 m)  diameter,  3,910 feet
 (1192  m)  of 6'-6" (1.98 m)  diameter,  1,540 feet
 (469 m)  of 8'-6" (2.6m)  diameter,  and 960 feet
 (293 m)  of 9'-6" (2.9m)  diameter earth tunnel;
 270 feet (82  m)  of 12-inch (30.48  cm)  diameter
 vitrified clay  pipe;  one monolithic concrete drop
 inlet  structure; three  monolithic  concrete side
 weir inlet structures;  three junctions;  twelve
 drop pipe connections;  manholes; catch basins;
 surface  restoration;  and all appurtenant and
 collateral work.
$53,947.41
March 16, 1970
                                  I
All construction work completed June 1, 1972
Construction Methods
The tunnel  sections were excavated with  a Caldwell earthmining
machine, equipped with hydraulic  jacks to expand  steel  ribs  and
lagging against the earth sides as mining progressed.   The
contract, as bid on, specified five sizes of tunnel but per-
mission was given to the Contractor to construct  only two sizes
namely 9'-6"  (2.9 m) and 6'-6"  (2.0 m) finished diameter after
reinforced concrete lining was poured.  Where a larger-size  sewer
than specified was constructed, there was no additional cost to
the City and the expense of revising the contract plans where
required was paid by the Contractor.

Shafts for most of the connections were excavated with a vertical
boring machine.  With a 50-foot (15.2 m)  high rig arid an adjust-
able cutter, shafts varying from 8 ft (2.4 m) to  20 ft  (6.1 m)
in diameter were drilled.
                               45

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           ADDITION = $11,525.00


           DEDUCTION =$23,043.24
The concrete tunnel lining was placed by pumping concrete into
the tunnel and around a collapsible, portable steel forni 70 feet
 (21.3 m) in length.
Temporary bulkheads were placed in all structures connecting to
existing sewers to prevent water and sewage from entering the
finished work from that source.  Provisions were made under
Contract No. 3 to remove these bulkheads when the system was
ready to be put into operation.

Contract Modifications:
1. Revisions were required to some of the contract plans because
the Contractor constructed larger tunnel sections than proposed.
This was done at his expense.              DEDUCTION = $2,500.00

2. Four time extensions were negotiated which totaled 328
calendar days.  The last extension of 171 days was required
because the remaining  surface restoration awaited suitable
weather.
 3. Surface restoration item.
4. Adjustment to Final Contract Quantities

 General;
 in the  25 years that the Auxiliary  Outlet Sewer  Program has been
 in existence, the  City of Chicago's Department of Public Works
 has  gained vast experience in the design, and supervision of
 construction, of sewers of this type.
 Traffic requirements were worked out  in  advance  with the Bureau
 of Street Traffic,  coordination was maintained with public and
 private utilities,  State Highway requirements  (for Motor Fuel
 Tax  fund approval)  were met, City codes  and  ordinances were
 followed, public protection  and safety were  stressed, and in the
 case of this  contract, 65 bid  items were included in the proposal.
 It  should not be surprising, therefore,  that there were no
 inadequacies  to report in  any  of the  areas aforementioned.
 Recommendations that have been received through  the years were
 incorporated in the Plans  and  Specifications.  The biggest
 factor in  earth tunneling was  to prevent movement of the
 surrounding earth  and  thus keep  settlement to  a  minimum so that
 adjacent  facilities were not damaged.  Strict  requirements to
 prevent settlement were included in our Specifications  and
 enforced by the Department of  Public  Works'  engineers who
 supervised the construction.
46

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                         Contract No. 2-B
                         Ten Drop Shafts
 Contractor;   Rock Road Construction Company
 Bid Price:    $3,415,688.00
 Financing;
 Location:
               2
               3
               4
               5
               6
               7
               8
               9
              10
 Contract
 Description;
 52% of construction cost was paid from City's
 share of MFT Funds.  Balance from Sewer Bond Funds.
 Ten Drop Shaft Structures located at:
 1.  Harding Avenue  & Berteau  Avenue
    Harding Avenue  & Mpntrose Avenue
    Lawrence Avenue & Harding Avenue
    Lawrence Avenue & Drake Avenue
    Lawrence Avenue & Kildare Avenue
    Lawrence Avenue & Kilbourn Avenue
    Lawrence Avenue & Laramie Avenue
    Lawrence Avenue & Long Avenue
    Lawrence Avenue & Menard  Avenues
    Lawrence Avenue & Melvina Avenue
In addition to the above ten structures; three drop
inlets? six side weir inlets; drain connections and
all other appurtenant and collateral work.
Estimated  Cost
Of Revising
City-Owned
Utilities:    $93,032.86
Construction
Starting
Date;

Status;
February 28, 1972

All construction work completed October 13, 1974.
Design;
During the design of "these drop shaft structures, the services
of the University of Minnesota, St. Anthony Falls Hydraulic
Laboratory, were obtainedo  Studies were made wi-|th models to
determine; the sizes of the shafts in relation to the quantities
of flows entering from the. high level sewers, ai.r entrainment,
the removal of the entrained air in the air collector in the boot
of the structure and the dividing wall and deflectors as well as
water surge conditions.
                               47

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Model Studies;

The, Lawrence Avenue Sewer System consists of a large deep;tunnel
for temporary storage of the surface runoff fed to it by a
series of drop shafts placed at intervals along the axis of the
tunnel.  Each drop shaft was designed to handle a variable
discharge, the peak value of which was different for each drop
shaft.  As the volume of runoff increases, the tailwater eleva-
tion will change from zero to a maximum governed by overflow
facilities.  The objective of the research was to investigate
the nature of the .flow in the drop shafts and to examine various
alternative designs suggested by the results of the studies„

The essential purpose of the drop shaft is to transport water
from one elevation and energy content to a lower elevation and
lower energy content.  Its function, then, is to dissipate the
energy of the incoming flow in the course of its passage down
the drop shaft to its new elevation and new flow pattern..  If
the drop shaft runs full, the energy change may be accomplished
by friction along the wall of the drop shaft so that its ;energy
at the bottom of the shaft is equal to that of the outflowing
water«,  When the drop shaft is partially full, the change in
energy is accomplished by impact of the falling water  on the
bottom of the shaft.  For variable discharges, this change of
energy is accomplished by a combination of boundary friction and
impact o

In a  system involving drop shafts of the height required by the
Lawrence Avenue Sewer System, dissipation of energy by boundary
friction  alone required  that  the diameter be relatively small
and that  the  flow velocities be quite high.  It also requires
that  the  drop shaft run  full  for all discharges that must be
handled. For  larger diameters and lesser velocities, the full
flow  condition can be attained in several ways.   It is possible
to maintain full  flow to drop shafts for  all discharges by using
a valve  at  the bottom of the  shaft.  Full  flow for a range of
discharges  could  also be attained by introduction of air in
varying amounts into the flow so that  the water bulk will be
increased sufficiently  to fill the  drop shaft.  From the
hydraulic point of view,  use  of  a valve at the foot of the drop
 shaft is  rather  attractive, but  it  would have  the disadvantage
of being located  far underground in the outlet tunnel  and would
require special  instrumentation  so  that the valve opening could
be  governed by the  inflow discharge.   In addition, the valve
would be subject  to possible  damage by sediment and other debris
 transported through the system.   In the second alternative,  that
                                48

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is, the introduction of air into the flow, all obstructions to
the flow and the necessity of moving parts would be eliminated,
but the problem involving the development of a homogeneous
mixture of air and water for all discharges in the drop shaft
will probably be more difficult.  Also, the design will have to
provide for entrainment of proper quantities of air during the
fall, its separation from the water and collection at the bottom,
and its removal before being carried into the tunnel.
Because of the advantages that appear to be inherent in the air
entraining type of drop shaft and because of experiences gained
in previous studies of such drop shafts, the investigations for
the Lawrence Avenue Sewer System were directed towards further
development of such structures.  Figures IV-16 through IV-26
show the results of experiments on several alternative systems
which involve the entrainment of air in the drop shaft and the
removal of this air from the flow at the bottom.

The development of the Type E-15 drop shafts consisted of
successive tests of modifications of the basic structure.  By
observing the functioning of each design, changes ;were intro-
duced which appeared to offer improved functioning.  By this
means the final arrangement was reached.  The Type E-15 drop
shaft will effectively remove entrained air before; it reaches
the downstream tunnel for all discharges up to itss capacity and
for all tailwater elevations above the crown of the downstream
                                                  i
tunnel.
The sloping crown of the air collector is very important in order
to effectively remove entrained air.  It was also demonstrated
by these tests that the slope of the air collector' s crown vshould
not be reduced, but an increase in slope would be beneficial to
its operation.  These experiments indicate that a slotted divider
wall is more effective than a solid divider wall.  If a slotted
divider wall is used, then deflectors are necessary to deflect
the flow away from the slot to provide the pressure distribution
that permits air to be drawn into the flow and distributed over
the cross-section.  Of the deflectors tested, it cippears that the
largest deflector was the most effective, both from the point of
view of air distribution and safety from damage by foreign bodies
that might be carried by the flow.                ;
                               49

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       Figure IV-16  Overall View -  Model

The drop shaft model was fabricated of a
transparent plastic so that the flow
patterns could be observed.  The photo-
graph shows a model slightly different
from Type E-15 but is included here to
demonstrate the relative size of the
model and its characteristic features.
                   50

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    Figure IV-17  Exit Conduit, Q=30Q  cfs, TW=10  ft..
                                C8.5m3/sec.),  (3m)
This photo shows that for 300 cfs and  a  low tailwater of 10  ft-
the air collector is effective in removing the  air.
                              51

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    Figure IV-18  Exit Conduit, Q=300 c£s, TW=100 £t.
                                (8.5m3/seci),  (30.5m)  ;
For higher tailwaters such as shown in this photograph,where
the elevation is 100 ft. the Type E-15 can easily remove
the air from the flow.                                ;
                               52

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    Figure IV-19  Exit Conduit, Q=600 cfs, TW=10 ft.
                                (17m3/sec.),  (3m)
For a discharge of 600 cfs and the tailwater maintained at
10 ft. the Type E-15 successfully removes the air from the
flow.
                              53

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     Figure IV-20  Exit Conduit, Q=600 cfs, TW=50 ft.
                                 (17m3/sec.),  (15.2m)
When the tailwater has been raised to 50 ft. the entrained
air quickly rises to the top of the air collector so that
none can escape into the downstream tunnel.
                              54

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     Figure IV-21  Exit Conduit, Q=600 cfs, TW=100 £t.
                                 C17m3/sec.) ,  (30.;5m)
For a tailwater o£ 100 ft. the air collector is still effective
in removing air.
                               55

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    Figure IV-22  Exit Conduit, Q=600 cf s , TW=190 £t.
                                (17m3/sec.),  (58m)
For a discharge of 600 cfs and a tailwater at 190 ft. the
entrained air has been considerably reduced and the air
collector can easily remove it from the flow so that none
escapes into the downstream tunnel.
                              56

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Figure IV-23   Vertical Shaft, Q=600 cfs, Effect
of Air Slots
                               -\. —_-	»
                               (17m5/sec.)
This photograph shows a discharge of  600 cfs. through  the
structure with a deflector over the air  slots.  The flow  is
homogeneous and no water escapes through the slots into the
air vent.
                               57

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   Figure IV-24   Entrance Conduit, Q=300  cfs, TW=225  ft.
                                    (8.5m3/sec.),  (68.6m)
When the discharge is 300 cfs with the  tailwater at  225 ft,
incoming tunnel runs only partly full but  there is no  air
entrainment.  The drop shaft is full and the pressure
difference between inlet and outlet is  relatively small.
(Shown for Type E-,17, E-15 flow patterns are identical at
this tailwater).
the
                               58

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    Figure IV-2 5  Entrance Conduit, Q=600 cfs, TW==190 £t.
                                    (17m3/sec.),  (58m)
When the tailwater is 190 ft. which is somewhat below the
elevation of the incoming tunnel, the discharge of 600 cfs
slows smoothly around the inlet and into the drop shaft
proper.  As it flows into the drop shaft, air is entrained
and mixed with the water.  The pressures in the incoming
tunnel are atmospheric and the water surface represents the
hydraulic gradeline.
                               59

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    Figure IV-26   Entrance Conduit, Q=60J)  cfs, TW=225  ft.
                                     (17m3/sec.),  (68.6m)
When the discharge is 600 cfs with the  tailwater  at  225 ft.,
the flow characteristics are essentially  unchanged from when
the flow is 300 cfs.
                               60

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Construction Methods:
During the construction of this Contract, work also was proceed-
ing on Contracts No<> 1 and No. 3 by another Contractor which
caused some conflict.  The excavation of the drop shaft struc-
tures was accomplished by the raise bore method through the
rock and by the down drill cutter machine through the overburden.
See Figures IV-27, IV-28, IV-29 and IV-30.  The form work for
the concrete connecting section from the main tunnel to the drop
shaft boot is shown in Figure IV-31.

Contract Modifications:
lo Relocation of existing sewers around drop shaft structures.
                                           ADDITION == $6,227.90
2. Restore existing 15-inch sewer in Laramie Avenue through no
   fault to Contractor.                    ADDITION == $7,935.50
3. Five time extensions were approved for a total of 407 days.
4. Additional manhole added.               ADDITION -~ $295.00
5. Final Contract Quantity adjustment.     DEDUCTION = $30,376.30
                         Contract No. 3

                  Pumping Station and Outfall
             Joint venture of James McHugh Construction Company.
             S.A. Healy Company, and Kenny Construction Company.
             $1,977,000.00
             52% of construction cost was paid from City's share
             of Motor Fuel Tax Funds„  Balance from Sewer Bond
             Funds, and from Federal Funds.
             Lawrence Avenue at North Branch of Chicago River.
            \ Pumping facilities; outfall structure; yard area;
Contractor
Bid Price:
Financing;
Location;
Contract
Description;J main shaft concrete lining; a discharge line to the
             M.SoD.C. interceptor; the removal of existing
             temporary brick, concrete and wooden bulkheads; the
             construction of brick weirs; and the performing of
             all appurtenant and collateral work.
Construction
Starting
Date;        April 17, 1972
Construction Status;
Figure IV-32 shows main shaft features installed following
placing of the concrete lining prior to installation of the
elevator.
Figure IV-33 shows one of the submersible pumps.
                               61

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Figure IV-27  Down drill rig at the drop shaft at Lawrence Ave
              and Menard Ave. for drilling through the over-
              burden prior to rock drilling by the raise-bore
              method.
                              62

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Figure IV-28  Close up view of the down drill cutter head for
              drop shaft excavation.
                               63

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64

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65

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Figure IV-31  Erecting form work for the concrete connecting
              section from main tunnel to the drop shaft boot.
                               66

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Figure IV-33

Submersible Pumps
Manufactured in Germany by the
KSB Pump Company.  Pumps were
designed for installation and
removal while the Main Shaft
is filled with water.

Characteristics:
(each of four)
Rated Capacity  5,000 GPM
                (315 I/sec.)
                  228 Feet
                  (69.5 m)
                  535 HP
                (542.5 lip-metric)'
                1,180 RPM
                   15 Ft.(4.6 m)
               28,000 Pounds
                (12,700 Kg)
Rated Head

Rated Power

Rated Speed
Height
Weight
                               68

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 As  of Feb.  1979,  the contract work was 96o65% completed.   Pump
 failures had occurred due to infiltration or intrusion of water
 into the upper chamber of the junction boxes which caused
 considerable delays.  This was believed to have been caused by
 water absorption through the power cable jacket after long
 periods of  submergence or through faulty junction boxes.
 Although the cables were installed per specifications,  it became
 necessary to research new cables which now have testing labora-
 tory approval.
                                                 I
 The use of  Okonite control cables now requires larger diameter
 reels and gear modifications in gear boxes to operate the reels.
 This problem is currently being resolved.       ;

 Contract Modifications:
 2.
 3.

 4.
 5.

 6.
 7.
 8.
 9.
10.

11.

12.

13.

14.
15.
16.
17,
18.
Revision of electrical work in the control chamber.
                                        ADDITION = $1,702.00
Domestic water supply change.           ADDITION = $3,680.24
Furnishing and placing four pump discharge diffusers.
                                        ADDITION
Heating system for pump supply line.    ADDITION
Additional reinforcement steel for baffle walls.
                                        ADDITION
Replacement of blown terminal boxes.    ADDITION
Starter-fuses  (spare parts).            ADDITION
Miscellaneous protection devices.       ADDITION
Modification of 14-inch ball valves.    ADDITION
Grate modification to clear hoisting chains.
                                        ADDITION
Disposal of debris for bulkhead removals.
                                        ADDITION
Plywood covers at main shaft  (freeze prevention).
                                        ADDITION
Replacement of manhole covers for Outfall
= $5,161.29
= $189.62

= $311.08
= $50,125.00
= $3,426.89
= $1,108o68
= $948.75

= $3,162,50

= $5,325.34

= $2,173.50
Structure  (36-inch-double openings).    ADDITION
Crane charges for Pump removals.        ADDITION
Pumping Costs.                          ADDITION
New Cables - Okonite, power & control.  ADDITION
Modifications for new cable reels.      ADDITION
Five time extensions have been approved as of April,
a total of 973 days.
  $612.38
  $4,606.70
  $3,474.60
  $73,729.00
  $20,013.00
    1978 for
                                69

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Contractor;
Bid Price:
Financing;
Location:
Contract
Description:
Construction
Starting
Date;
Status:
           Contract No. 4

    Additional High-Level Sewers

Jay-Dee Contractors, Inc.
$2,644,875.00
Sewer Bond Funds
In Drake Avenue from Lawrence Avenue to Argyle
Street; in Long Avenue from Lawrence Avenue to
Montrose Avenue; in Melvina Avenue from Lawrence
Avenue to Eastwood Avenue to Narragansett Avenue
to Montrose Avenue; and in Strong Street from
Moody Avenue to Austin Avenue to Higgins Avenue.

3,930 feet (1198 m) of 6'-0"  (1.8 m) diameter and
4,610 feet (1405 m) of 5'-0"  (1.5 m) diameter earth
tunnel; 1,245 feet  (379 m) of 60-inch  (152.4 cm)
diameter reinforced concrete pipe; one monolithic
concrete drop inlet structure; three monolithic
concrete side weir inlet structures; eight drop
pipe connections; manholes, catch basins, surface
restoration;  and all appurtenant and collateral
work.
May 1, 1974
All construction work completed June 30, 1975.
Contract Modifications;
1. The Contractor proposed to construct the Drake Avenue branch
by the jacking-tunneling machine method.  This allowed the City
the advantage of minimal street replacement and traffic disrup-
tion for a credit of surface restoration items.  See Modification
No. 3.                                    ADDITION = $27,340.00
2. Spot welding of air vent gratings to frames.  (Vandalism pre-
vention).                                 ADDITION = $143oOO
3. Total adjustment to Contract.          DEDUCTION = $47,852.81

LAWRENCE AVENUE TESTING DEMONSTRATION
The entire Lawrence Avenue System did not receive flow until the
outfall and pumping station included in Contract No. 3 were
completed and the pumps were installed.

In accordance with our agreement for Federal  (USEPA) Demonstra-
tion Grant Funds an extensive testing program must be undertaken
with samples taken of storm overflows from sewers of and
influenced by the Lawrence Avenue System to demonstrate its
                               70

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performance..  Sampling and testing for the pre-operation
condition has been completed.

The sampling and testing for the post-operation condition will
be conducted when the Pumping Station is fully operational.
This work will consist of testing for the following;' Biochemical
Oxygen Demand, Chemical Oxygen Demand, Dissolved Oxygen,
Settleable Solids, Suspended 'Solids, Fecal Coliform, Organic
nitrogen, Ammonia nitrogen and Spectroanalysis for metals.  The
results of this sampling and testing program will be covered in
the Phase II, Final Report.

RELATIONSHIP OF THE LAWRENCE UNDERFLOW SYSTEM
TO THE TUNNEL AND RESERVOIR PLAN

The Metropolitan Sanitary District of Greater Chicago is now
constructing segments of the Tunnel and Reservoir Plan  (TARP).
This system is comprised of a series .of rock tunnels and
reservoirs.  The tunnels are approximately 250 feet  (76 m) below
the surface and are designed to capture combined sewer flows,
which presently overflow to the river during times of storm,
and convey them to storage reservoirs for containment until
capacity is available at the treatment plants.

When the Mainstream Section of the TARP is in operation, the
pumping station of the Lawrence Avenue System will be a branch
of the entire waterway flood and pollution control system.  The
capacity of the Lawrence System to handle combined sewer over-
flows will then be increased.  This is significant because the
rock tunnels of the Lawrence System can then be used as an out-
let for flows originating from areas beyond its currently
designed drainage area of 3600 acres  (1457 hectares).  It is
recommended that the maintenance and operation of the Lawrence
Avenue System be undertaken by the Metropolitan Sanitary
District of Greater Chicago who have personnel qualified to
handle pumping stations of this type.  In addition, the system
will eventually be a direct connection to the District's Tunnel
and Reservoir Plan.
                                71

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                             SECTION V

                    TUNNEL AND RESERVOIR PLAN FOR
                        THE CHICAGOLAND AREA
 DESCRIPTION

     The Tunnel and Reservoir Plan (TARP),  currently under
 construction by the Metropolitan Sanitary  District  of  Greater
 Chicago (MSDGC),  has been selected from fifty-one considered
 proposals  as the most  cost-effective method which will prevent
 combined sewer overflows  to  the  waterways,  except for  the
 recurrence of  the three largest  storms  of  record, and  will
 eliminate  backflow from the  waterways to Lake Michigan.  During
 spills  from these events,  the flows would  be relatively clean
 since the  highly-polluted, "First Flush,"  would be  captured by
 TARP during the  early  stages of  rainfall.

     TARP is actually made  up of  125 miles  (201 km)  of  tunnels
 including  their  related collector systems,  an aquifer  protection
 system,  two on-line reservoirs,  three terminal  (retention)
 reservoirs,  and  treatment  facilities.   See  Figure V-l.

     Based  on currently available  or anticipated funding,
 construction has been  divided into four separate systems,
 viz; Mainstream, Calumet, Main(Lower) Des  Plaines,  and Northwest
 (Upper)  Des  Plaines.   For the Mainstream and Calumet Systems,
 Stage 1  construction is primarily for pollution control and
 Stage 2  is primarily for flood control.  Stage 2 construction
will follow  as Federal funding becomes  available.

Mainstream System

    The combined sewer overflows  from about 60 percent of the
 study area are captured by the Mainstream tunnels and conveyed
to storage reservoirs.  A collector system with drop shafts is
used to collect the runoff from- the overflow outlets and divert
it to the tunnels.  Basically, the system provides a free
draining outlet for some 20 communities, portions or all of
                              72

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            TUNNEL AND RESERVOIR PLAN
          Figure V-l  Tunnel and Reservoir Plan

Tunnel and Reservoir Plan as proposed by the Metropolitan
Sanitary District of Greater Chicago.
                           73

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which are located in the affected service area.  However, system
design does permit spillage in the North Shore and Main.Chicago
areas, but only if the most severe storms of record were to
recur.  The rate and volume, though, are controlled so that the
spillage does not become a source of damage or pollution.
Sufficient in-line storage is provided to avoid spillage in the
area tributary to the North Branch of the Chicago River upstream
of the North Shore Channel.

    Some 56 miles  (90 km) of Mainstream tunnels and extensions
are required! to convey the overflows to the terminal reservoir
near the existing West-Southwest treatment plant.  Plans call
for the reservoir to be located in a commercial quarry about
2 miles  (3.2 km) south and west of the plant.  This reservoir
will provide storage of 82,000 acre-feet  (10,115 hect-m).  In
addition, an on-line underground reservoir adjacent to the
existing North Side treatment plant has been provided.  It
controls only in-line back up and permits the use of smaller
sized tunnels in the northern reaches of the Mainstream Tunnel.
The room and pillar construction method will be used to create
this 2,900 acre-foot  (358 hect-m) storage area in the rock
strata underlying the plant.
Calumet System

    The Calumet system is not interconnected with the Mainstream
system.  It is an independent system serving some 14 communities,
totally or in part.  Slightly over 36 miles  (58 km) of tunnels
are needed to capture the overflow from a watershed that amounts
to about 24 percent of the study area.  The tunnels are sized
to permit limited spillage to the Calumet River and Calumet-Sag
Channel.  However, spills will not be allowed into that portion
of the Little Calumet River upstream of its junction with the
Calumet-Sag Channel.  The flows are conveyed to a terminal
reservoir, also located in a commercial quarry.  This quarry is
located in Thornton, Illinois, several miles away from the
Calumet treatment plant and will provide 39,000 acre-feet
 (4,811 hect-m) of storage.  Part of the proposed tunnel system
serves as an interconnector between the reservoir and treatment
plant.  The excavated rock will be stockpiled in the quarry and
eventually incorporated in the future sales of aggregate lime-
stone and for other uses.
                               74

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Main  (Lower) Des Plaines System

   The excess overflow from the 19 communities interconnected
with this tunnel system will be conveyed to the terminal
reservoir that serves the Mainstream system, located near the
West-Southwest treatment plant.  No spillage will be permitted
from the over 23 miles  (37 km) of main-line tunnels and
extensions.  The applicable water quality standards,, not the
in-stream capacity, require this design constraint.  Approxi-
mately 13 percent of the study area is located in the tributary
watershed.
                                                 ,i
Northwest  (Upper) Des Plaines System

   This system will intercept sanitary and combined sewage flows
arising within the Upper Des Plaines  (O'Hare) Basin and divert
these flows to the O'Hare Water Reclamation Plant  (OHWRP) for
treatment.  The project includes all or parts of the communities
of Arlington Heights, Buffalo Grove, Des Plaines, Elk Grove
Village, Mount Prospect, Rolling Meadows and Wheeling and
unincorporated areas in parts of the Townships of Elk Grove,
Maine, Northfield, Palatine and Wheeling.  Current plans call
for the installation of 7.7 miles  (12.4 km) of main-line tunnels
and extensions.  The tunnels are sized to prevent any spillage
to the waterways of the excess runoff from the communities
interconnected to the system.  Water quality standards and
in-stream capacity applicable to the receiving watercourses,
Weller Creek and Feehanville Ditch, preclude any spillage.  Also
included in the system are two reservoirs:  (1) an 850 acre-foot
(105 hect-m) on-line surface reservoir at the upper end of the
tunnel system; and (2) a terminal reservoir with some 2,700
acre-feet  (333 hect-m) in storage capacity.  Co-located with the
terminal reservoir will be a new treatment plant.  This plant
will be used to process the flows from the surrounding, rapidly
expanding suburban area.  This action will help relieve the
overload to the North Side plant which currently handles these
flows.

PRESENT AWARD PROGRAM

   The Tunnel and Reservoir Plan is the largest tunneling
program in the history of the metropolitan Chicago cirea.  The
MSDGC has already awarded contracts for 47 miles (75.6 km) of
rock tunnels ranging in diameter from 9 feet (2.7 m) to 33 feet
(10.1 m), 137 drop shafts from 4 feet (1.2 m) to 18 feet  (5.5 m.)
in diameter and the associated connecting structures,totalling

                               75

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a bid price of $733,403,475.  Additional contracts for an
estimated cost of $376,679,924 will be advertized before the
end of 1979.  The breakdown for each area is given below.

Mainstream System

    Contracts have already been awarded for 21.4 miles  (34.4 km)
of lined rock tunnels and 9.8 miles  (15.8 km) of unlined
tunnels 13 feet  (4.0 m) to 33 feet  (10.1 m) in diameters and
112 drop shafts with finished diameters varying from 4 feet
(1.2 m) to 18 feet (5.5 m) and depths varying from 200 feet
(61 m) to 266 feet (81 m) for a total cost of $543,633,595.
These cover the first stage tunnels from 59th Street, near the
proposed storage reservoir site, to Wilmette Harbour on the
north end.  Contracts have also been awarded for 128 structures
connecting existing outfalls to the Shaft-tunnel system from
Damen Avenue to Addison Street for a total of $46,094,860.

    Construction work to be advertized by the end of 1979,
for an estimated cost of $303,134,488 includes 6 miles  (9.7 km)
of lined tunnel and 2.4 miles (3.9 km) of unlined tunnel from
10 feet (3 m) to 33 feet  (10.1 m) in diameter, 3 drop shafts,
4 feet (1.2 m) to 9 feet  (2.7 m) in diameter, 82 connecting
structures and a pumping station.

Calumet System

    A contract for $79,256,370 has been awarded for 9.2 miles
(14.8 km)  of unlined rock tunnels varying from 9 feet (2.7 m)
to 21 feet (6.4 m) in diameter and 17 drop shafts with finished
diameters 5'-8"  (1.7 m) to 15'   (4.6 m) and depths varying from
249 feet (76 m) to 331 feet  (101 m).  This covers the section
from Crawford Avenue to the Calumet sewage treatment plant.

The award program for the next year includes a pumping station
for $53,400,000 and some 27 connecting structures at an
estimated cost of $20,145,436.
                               76

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Des Plaines System  (Including both Upper and Lower)

    All work for the Upper Des Plaines System is already under
contract including:  construction of 6»6 miles  (10.6 km) of
lined rock tunnels varying from 9 feet  (2.7 m) to 20 feet  (6.1 m)
in diameter, 1.1 mile  (1.8 km) of a 5 foot  (105 m) diameter
earth tunnel, 8 drop shafts, varying from 5 feet  '(1.5 m) to
9 feet  (2.7 m) in diameter, 130 feet  (40 m) to 150 feet  (46 m)
deep and connecting structures at some 29 locations.  The
contract price of tunnels and shafts is $59,820,000 and that of
the connecting structures is $4,598,650.

    No work is contemplated for the Lower Des Plaines system
before 1980.
                               77

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                                  TECHNICAL REPORT DATA
                           (Please read Instructions on the reverse before completing)
. REPORT NO.
EPA-600/2-80-014
                                                           3. RECIPIENT'S ACCESSION NO.
. TITLE AND SUBTITLE
LAWRENCE AVENUE UNDERFLOW SEWER SYSTEM
Interim  Report
Planning and Construction
              5. REPORT DATE
               March 1980  (Issuing Date)'
              6. PERFORMING ORGANIZATION CODE
. AUTHOR(S)
                                                           8. PERFORMING ORGANIZATION REPORT NO.
Louis  Koncza, Donald H. Churchill,  and  G.  L.  Miller
i. PERFORMING ORGANIZATION NAME AND ADDRESS
City of Chicago, Department of  Public  Works
Bureau of Engineering, Water and  Sewer Programs
320 North Clark Street
Chicago,  Illinois  60610	
              10. PROGRAM ELEMENT NO.

                   1BC822,  SOS 31. Task #06
              11. CONTRACT/GRANT NO.
                   11020 EMD
12. SPONSORING AGENCY NAME AND ADDRESS
Municipal  Environmental Research  Laboratory--Cin.,OH
Office of Research and Development
U.S.  Environmental Protection Agency
Cincinnati, Ohio  45268       	___^
              13. TYPE OF REPORT AND PERIOD COVERED
                Interim 1966-1978   	
              14. SPONSORING AGENCY CODE
                   EPA/600/14
15.SUPPLEMENTARY NOTES -Supplement  to  EPA-11020 02/71 "Deep
 Project Officers: Clifford Risley,  Jr.,  (312) 353-2200,
 Traver,  (201) 321-6677, FTS '340-6677	
             Tunnels  in Hard Rock"
             FTS  353-2200;  and Richard P.
16. ABSTRACT
A new and bold concept in design  of urban drainage systems was  developed as a step
forward in the solution of combined sewer overflow problems.  A deep  tunnel  in bed
rock about 200 to 250 feet (61  to 76!;jn)  below the surface was designed  and constructed
for the Lawrence Avenue drainage  basin in Chicago.  Utilization of modern tunnel  bor-
ing machines made the project  economically competitive with  conventional  sewers while
reaping additional benefits of ease in construction, no disturbance to  traffic^and
least inconvenience to public.   In addition, the tunnel sewer will serve as a reservoir
totally capturing smaller storms, and trapping a significant portion  of the first flush
of pollutants from larger storms.  The entrapped pollutional load  will  be pumped to a
treatment plant through a pumping station to be operated only at the  end of the storm,
for dewatering the tunnel.  The project is expected to reduce,  to  a large extent, the
combined sewer overflows to the waterways.
17.
                                KEY WORDS AND DOCUMENT ANALYSIS
                  DESCRIPTORS
                                              b. IDENTIFIERS/OPEN ENDED TERMS
                                                                           COSATI Field/Group
  Drainage, Water pollution,  Surface water
  runoff,  Runoff, Storm sewers,  Overflows,
  Combined sewers, Tunneling  (excavation),
  Tunneling machines, Flood control,
  Excavating equipment, Underground storage,
  Reservoirs
  Deep  tunnels,  Drop
  shafts,  Hydraulic
  modeling,  Combined
  sewer overflows,
  Inline storage
                13B
18. DISTRIBUTION STATEMENT


         RELEASE TO PUBLIC
 19. SECURITY CLASS (ThisReport)
     UNCLASSIFIED
           21. NO. OF PAGES

             •   88
 20.!
his page)
                            22. PRICE
EPA Form 2220-1 (Rev. 4-77)
78
     ft U.S. GtfKRNMENTPRINTING OFFICE: 1980 -657-146/5642

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