A portion of the City of Chicago 1911 Map of Main Outfall Sewers upon which District engineers positioned planned sewage treatment facilities to serve the west and south sewer districts and the routes of planned intercepting sewers in 1919. The proposed site of the Southwest plant and actual site of both Southwest and West Side plants are added. (Photo by author)

August 11, 1922. The Laramie Avenue outlet sewer outfall to the Sanitary & Ship Canal discharged raw sewage and stormwater from 1914 to 1930, after which the sewage was diverted to the West Side plant and the outfall was used to discharge combined sewage and stormwater. Prior to its construction, sewage and stormwater were discharged to Ogden Ditch. (MWRD photo 9370)

July 16, 1928. The West Thirty-Ninth Street sewer looking east from a point east of Central Avenue. The sewer was constructed 15 years earlier and construction recently started on battery B Imhoff tanks at the West Side plant. The north cableway tower appears in the right background. The sewer is crossing Ogden Ditch, which flows in a northeast-southwest direction, but is mostly stagnant except in wet weather. (MWRD photo 14163)

The Oak Park outlet sewer in Chicago Avenue was built by tunnel. Miners on December 13, 1921, used the only method available, manual labor, to excavate the tunnel. Timber sheathing and posts supported the soil. Screw jacks were used to force timbers into place and for additional support. The outlet sewer initially discharged to the Des Plaines River at Chicago Avenue. (MWRD photo 8702)

Construction by tunnel required vertical shafts at intervals along the route of the sewer for access to the tunnel below. By November 29, 1921, the contractor, Nash Brothers, had built this head house over the access shaft at Chicago and Kenilworth avenues for the Oak Park outlet sewer. Each head house contained a steam-driven hoist to move materials and workers between the street and tunnel levels. (MWRD photo 8689)

Part of the Des Plaines intercepting sewer in Maywood was built by the open cut method. As the trench is excavated, timber sheathing is placed vertically, braced by horizontal timber struts to hold the soil in place. On August 8, 1919, construction of the concrete sewer along Chicago Avenue is in progress. Upon completion of the sewer, the timber struts and sheathing are removed before backfilling the trench. (MWRD photo 7197)

An initial step in sewer construction is removing trees on the permanent and temporary easements. On May 9, 1924, a crew is clearing trees and grubbing stumps near Iowa Street in River Forest for the Elmwood Park outlet sewer that will discharge to the Des Plaines River plant via the Elmwood Park pumping station. Excess combined sewage and stormwater will be discharged to the Des Plaines River at North Avenue. (MWRD photo 10584)

The Elmwood Park sewer was constructed by the open cut method and the Elmwood Park pumping station required excavation of a large shaft. On June 13, 1924, an excavating machine is being erected at North and Thatcher avenues in preparation to excavate the vertical shaft. (MWRD photo 10732)

July 21, 1924. Concrete for the 8-foot diameter Elmwood Park sewer along Chicago Avenue is being poured into the formwork in the background. In the foreground, the concrete has cured and the trench partially backfilled. The crew is beginning to remove the timber struts and sheathing before backfilling the remainder of the trench. (MWRD photo 10956)

June 19, 1925. An engineer is inspecting a manhole structure and backfill along the Elmwood Park sewer along North Avenue. The backfill will be graded level and compacted below the top of the manhole to allow for street construction. With completion of the sewer, homes can be built in the undeveloped area. (MWRD photo 11847)

The Salt Creek intercepting sewer was constructed rapidly through undeveloped areas in the western suburbs. On November 1, 1927, a mobile crane is being used to remove buckets of tunnel muck from an open shaft along Washington Avenue in Brookfield and dump the muck into a truck to be hauled away. Men in the background are looking down into the shaft. (MWRD photo 13575)

Most of the Salt Creek intercepting sewer was constructed by the tunnel method. On November 29, 1927, a head house is being erected over a vertical shaft that will provide access to the tunnel along Riverside Road in Riverside. A steam-powered hoist will be installed in the head house to move materials, tunnel muck and workers between the street and tunnel levels. (MWRD photo 13625)

June 13, 1928. Salt Creek intercepting sewer section one near the influent to the West Side pumping station. Looking southwest, the first few hundred feet were constructed by open cut near the pumping station intake. In the background are spoil piles along the north bank of the Sanitary & Ship Canal. Nearly invisible before the spoil piles is the sewer tunnel entrance. (MWRD photo 14052)

June 13, 1928. Closer to the tunnel entrance for the Salt Creek intercepting sewer construction, two empty muck cars are positioned on the tracks leading into the tunnel. On either side of the entrance is ventilation equipment. Notice the spacing of the lights—the tunnels were dimly lit. The muck cars will be lifted for dumping by a crane on the platform at right. (MWRD photo 14051)

April 30, 1928. A crane is lowering a section of precast reinforced concrete pipe into a sewer trench for the Howard Street outfall sewer in Park Ridge. Looking west toward the Des Plaines River, a dragline bucket in the foreground is excavating the sewer trench. This illustrates poor practice in sewer construction. Proper subgrade material, such as gravel, should have been placed under the sewer, to create a uniform bed to distribute the load of the sewer pipe. (MWRD photo 13928)

August 30, 1934. A rescue crew for construction of West Side intercepting sewer section 7 is equipped with self-contained breathing masks and is beginning a training drill. Following the tragic tunnel fire in 1931, one of the adopted safety precautions was to have tunnel workers trained and equipped for rescue operations. (MWRD photo 18530)

October 25, 1934. A typical emergency exit is shown for West Side intercepting sewer section 5 under Jefferson Street at Monroe Street. Another safety precaution was the requirement for emergency exits for all sewers constructed by the tunnel method. (MWRD photo 18883)

August 28, 1934. Looking south from Kinzie at the Chicago and North Western Railway single leaf bascule bridge over the North Branch. This landmark bridge has been idle in the open position since 2000. The two men mark the east-west centerline of the West Side intercepting sewer section 7 after it crossed under the North Branch. The range pole marks the point on the ground below which will be the junction where West Side intercepting sewer section 10 flows in from the north. (MWRD photo 18519)

November 9, 1934. Looking east from the east end of the Kinzie Street bridge over the North Branch, an access shaft is being excavated for construction of the junction chamber for West Side intercepting sewer section 10 to connect with section 7 running under Kinzie Street. The railway freight office is no longer there. The Merchandise Mart in the background is a new building, opened in 1930. (MWRD photo 19009)

November 27, 1934. A crew of miners excavating the north tunnel heading from the Quincy Street shaft for West Side intercepting sewer section 6 under Jefferson Street takes a break. The background shows the typical corduroy appearance of the soft clay and the miners are protected by steel liner plates and ribs to hold the native clay in place. Using steel instead of wood was another change in tunnel construction practice resulting from the 1931 tunnel fire. (MWRD photo 19118)

February 15, 1935. The entrance to the air lock from the completed sewer for West Side intercepting sewer section 7. At right, the air-tight steel door is open for the photographer. Tunneling through soft clay required the use of an air lock to maintain increased air pressure at the heading. (MWRD photo 19352)

February 25, 1935. Two miners constructing West Side intercepting sewer section 7 under Kinzie Street are slightly bent holding the heavy slabs of soft clay. This view is looking west into the west heading from the shaft at Wabash Avenue; a similar scene could be seen in the east heading. (MWRD photo 19469).

May 31, 1935. An engineer is inspecting the completed West Side intercepting sewer section 6 at the junction of its east-west route under Wacker Drive and its north-south route under Franklin Street. The route and configuration of the sewer is complicated by a connection to a City sewer and the substructure of Wacker Drive. (MWRD photo 19804)

November 4, 1936. Most sewer construction tunneling was through soft clay, but three types of material were found here. Above the soft clay at the bottom is a layer of concrete topped with wooden debris. At this location, West Side intercepting sewer section 4A was built about 50 ft. west of the west dock wall of the South Branch. Looking south, the south heading is about 50 ft. south of Polk next to the foundation of a building demolished when the river channel was widened. (MWRD photo 22346)

April 16, 1936. Most of the Southwest intercepting sewer was constructed by tunnel, thus street closings were limited to where shafts were sunk for tunnel access as shown in the background. Tunneling sometimes resulted in subsidence as shown in the foreground at the northwest corner of the intersection of Keeley and Lyman streets for sewer section 5. (MWRD photo 21050)

October 1, 1936, looking south. Care was exercised each time a north-bound trolley car passed the construction shaft. Underpinning the tracks was often required to prevent subsidence. Connection of the Chicago Western Avenue sewer to Southwest intercepting sewer section 3 required a shaft adjacent to the tracks of the Chicago Surface Lines. (MWRD photo 22151)

Concrete for construction of Southwest intercepting sewer is mixed at ground level, placed in side-dump rail cars and lowered in the access shafts to the tracks along the route of the sewer. In section 3, on November 21, 1935, the loaded dump cars are pushed by an electrical locomotive to the end of the completed sewer in the east heading. The concrete is dumped into a hopper in the raised floor of the sewer. (MWRD photo 20563)

November 21, 1935. The same operation on the same day as in the preceding photograph occurs in the west heading from the same shaft on the route of Southwest intercepting sewer section 3. The concrete in the hopper drops onto a conveyor belt and is moved up to the crown of the sewer closer to the heading as shown in the background, where it is placed in the sidewall forms of the sewer. (MWRD photo 20564)

July 23, 1940. Before and after photographs are taken of all structures along the route of the Southwest intercepting sewer. At 3905 South Wentworth Avenue, surveyors are making preconstruction measurements to have for comparison with postconstruction measurements should any claims for settlement damages be filed. The west elevation of this two-story brick building may be susceptible to cracks if settlement occurs on sewer section 10. (MWRD photo 26091)

This building on the southwest corner of State Street and Pershing Road required extra support during construction of a connection chamber where the local State Street sewer will flow into Southwest intercepting sewer section 10. Looking west at the east building façade, construction will begin soon after August 7, 1940. (MWRD photo 26172)

A large rectangular pit was excavated, the sides held in place with sheeting and braced with horizontal timbers, to construct the connection at State Street for the city sewer to Southwest intercepting sewer section 10. By August 29, 1940, the pit was nearly complete as the final horizontal timbers were placed. Looking northwest, glass storefronts have been protected with wood covers and the building shored with vertical struts. (MWRD photo 26227)

August 29, 1940. Another view on the same day looking south shows more clearly the protection for windows and the vertical struts supporting the east elevation of the building. Sheeting and bracing is installed as the pit is deepened. When complete, forms will be built for the sewer connection and then concrete can be placed. Several connections were made to Southwest intercepting sewer section 10 at north-south streets. (MWRD photo 26228)