───────────────┬─────────────┬─────────────┬─────────────┬────────────── Section │Area in Terms│ Hydraulic │ Vert. Dia. │ Source │ Vertical │ Radius in │_D_ in Terms │ │ Diameter │ terms of │ of Dia. _d_ │ │Squared _D_^2│Vertical Dia.│of Equivalent│ │ │ _D_ │ Circular │ │ │ │ Section │ ───────────────┼─────────────┼─────────────┼─────────────┼────────────── Circular │ 0.7854│ 0.250 │1.000 │ Egg │ 0.5150│ .1931│1.295 │Eng. Record, │ │ │ │ Vol. 72: 608 Ovoid │ 0.5650│ .2070│1.208 │Eng. Record, │ │ │ │ Vol. 72: 608 Semi-elliptical│ 0.8176│ .2487│1.041 │Eng. News, │ │ │ │ Vol. 71: 552 Catenary │ 0.6625│ .2237│1.1175 │Eng. Record, │ │ │ │ Vol. 72: 608 Horseshoe │ 0.8472│ .2536│0.985 │Eng. Record, │ │ │ │ Vol. 72: 608 Basket handle │ 0.8313│ .2553│0.979 │Eng. Record, │ │ │ │ Vol. 72: 608 Rectangular │ 1.3125│ .2865│0.7968 │Hydraulic │ │ │ │ Dgms. and │ │ │ │ Tbls. │ │ │ │ Garrett Square (3 sides│ 1.0000│ .333 │0.7500 │Eng. Record, wet) │ │ │ │ Vol. 72: 608 Square (4 sides│ 1.0000│ .250 │1.0000 │Eng. Record, wet) │ │ │ │ Vol. 72: 608 ───────────────┴─────────────┴─────────────┴─────────────┴────────────── [Illustration: 1. Standard Egg-shaped Section, North Shore Intercepter, Chicago, Illinois. ] [Illustration: 2. Rectangular Section, Omaha, Nebraska, Eng. Contracting, Vol. 46, p. 49. ] [Illustration: 3. Trench in firm ground. 4. Trench in Rock. NOTE.—Underdrains and Wedges to be used only when Ordered by the Engineer. ] [Illustration: 7. Brick and Concrete Sewer showing cunette. ] [Illustration: 5. Soft Foundation. 6. Wet ground. ] [Illustration: 8. Brick and Concrete Sewer, Evanston, Ill., Eng. Contracting, Vol. 46, p. 227. ] FIG. 22. [Illustration]