All surface runoff from areas expected to yield good quality water such as roofs, paved areas, lawns and discharge from ground water collection systems must be excluded from separate sanitary sewers. Runoff from certain uncovered areas of an industrial plant during the initial period of rainfall is likely at times to contain appreciable concentrations of materials. Such areas as rail car or truck unloading stations, tank farms or unhoused process equipment may be expected to receive material from leaks, spills, drips, tank washouts, tank overflows, hose drainages and clean-outs. Limited and isolated areas can be drained to the sanitary sewers so that both the wet and dry weather flows receive treatment. If such an area is too extensive to permit admittance to the sanitary sewer of the quantity of rainfall runoff involved, a system for admitting the first flush of runoff to the sanitary sewer and automatic division of additional runoff to the storm sewer shall be installed. The diversion should be made after 0.25 inches (0.64 cm) of rainfall. An alternative to the direct diversion of wastewaters from these areas is the use of approved holding facilities with controlled discharge. Basements shall be drained to the sanitary sewer because the wastewaters from washing machines, portable laundry tubs and shower baths can cause gross pollution of storm sewer outlets. Foundation drains are required to be discharged to a storm sewer. Unpolluted water from air-conditioning systems, industrial cooling operation, swimming pools and so forth shall be discharged to the storm sewers or directly to natural drainage outlets.
(Ord. 78-4, passed 2-13-1978; Ord. 92-20, passed 9-28-1992) Penalty, see § 51.999