────────┬────────┬────────────┬─────────┬─────────── │ │ │ │ Diameter│ Feet │ │ │ of Sewer│Progress│ Location │Authority│ Remarks │per Day │ │ │ │ │ │ │ ────────┼────────┼────────────┼─────────┼─────────── 7′ 0″│ │ │ │ 8′ 11″│ 60│Gary │Gillette │9–hour day │ │ │ │ │ │ │ │ │ │ │Metcalf │General 4′ 0″│ 36│ │ and │ average │ │ │ Eddy │ │ │ │ │Concrete 6′ 8″│ │Denver │Gillette │ invert │ │ │ │ │ │ │Eng. │ │ │Springfield,│ Con., │ 2′ 9″│ │ Mass. │ Jan. │ │ │ │ 16, │ │ │ │ 1907 │ 5′ 6″│ 110│Gary │Gillette │ 6′ 6″│ │ │Gillette │Exceptional │ │ │ │ speed │ │ │ │Tunnel 2′ 9″│ 13.9│Syracuse │Gillette │ 12–hour │ │ │ │ day 16′ 0″│ 22│Chicago │Gillette │First year │ │ │ │ 16′ 0″│ 35│Chicago │Gillette │Second year 3′ 6″│ │St. Louis │Gillette │ 9′ 6″│ 12.5│Chicago │H. R. │ │ │ │ Abbott │ │ │ │ │Lock joint 3′ 6″│ 30│ │ │ and tile. │ │ │ │ 10–hour │ │ │ │ day ────────┴────────┴────────────┴─────────┴─────────── If inside forms are to be used they are made as units in lengths of 12 or 16 feet for wooden forms, and 5 feet for steel forms. The inside form is supported by precast concrete blocks placed under it and which are concreted into the sewer. It is held in position by cleats nailed to the outside form, to the sheeting, or wedged against the outside of the trench. In some cases, particularly where steel forms are used, the inside form is hung by chains from braces across the trench as is shown in Fig. 129. The form is easily brought to proper grade by adjustment of the turnbuckles and is then wedged into position to prevent movement either sideways or upwards during the pouring of the concrete. It may be necessary to weight the forms down to prevent flotation. Cross bracing in the trench which interferes with the placing of the form is removed and the braces are placed against the form until the concrete is poured. They are removed immediately in advance of the rising concrete. [Illustration: FIG. 129.—Blaw Standard Half Round Sewer Form, Suspended from Overhead Support. Courtesy, Blaw Steel Form Co. ]