Maintaining operations during construction; and. It is recommended that conditions of no snow cover be assumed for purposes of determining the maximum depth of frost. Lifecycle cost, including maintenance and calibration requirements and hydraulic head loss (pumping costs), should be considered. A minimum of two parallel compartments, with a depth that will provide a diffuser submergence of not less than 2.3, A mixing compartment having a detention time of at least three minutes; and. A minimum velocity of 0.5 m/s (1.6 ft/s) is recommended for all wastewater lines. A minimum acceptable time-to-freeze of approximately 96 hours should be considered an acceptable level of risk. A further advantage of mains located along the rear lot line is that the manholes containing water line valves and hydrants and freeze protection controls can be elevated in cylindrical shape approximately 1.0 m (3 ft) above grade. Pre-insulated pipe should not be buried with less than 0.6. Placing the mains at the rear lot line reduces service line connections and permits service lines of equal length on both sides of the main. When concentrations exceed 10. Centrifuges dewater residuals by forcing water from solids under high centrifugal forces. Where ten or more residential lots or dwelling units are to be developed or exist and the average lot size is less than 0.8 hectares (2 acres), a communal water supply system should be provided as long as local conditions are favourable to the development of a suitable ground or surface water supply; and. Any other factor that may be relevant to the design. If special fittings and accessories are required that may be difficult to obtain, replace and service, this should be considered at the design stage and spares purchased during construction. Capacity of the pumping station with the two largest units (including the fire pump[s], if any) out of service if the pumping station serves a pressure zone that does not have adequate floating storage available and is the sole source of supply in the area. The designer should refer to the National Research Council of Canada (NRC), Institute for Research in Construction for information used to determine frost penetration. As the length of the loop increases, the risk of service loss also increases in case of a shutdown due to a problem along the line. Re-laying of the entire service connection at an adequate depth of cover; Replacement of the entire service connection with a new service connection installed in a pre-insulated service duct, with thermostatically controlled heat tracing if required; Provision of insulation over the existing service connection, with heat tracing if required; or. Side entry designs are less likely to be damaged by anchors; and. Coagulation upstream of the membrane process is not needed for effective pathogen removal. Withdrawal of water from more than one level if quality varies with depth and during seasonal events; Inspection manholes for pipe sizes large enough to permit visual inspection and/or diver entry for larger intakes; and. Alternative design practices are outlined in Section 12.8 Alternative Design Practices. Prevention of flooding by providing overflow; Maximum velocity of treated water in pipe and conduits to filters of 0.6. Capacity of the raw water pumping station able to supply the water treatment plant design capacity with the largest unit out of service. For each groundwater well, a schematic diagram showing details of well construction including proposed pump installation level, and well screen data including well screen entrance velocities; General layout plans for all major facilities of the works (, Construction scale plan and profile drawings (with dimensions and elevations) of all facilities proposed to be constructed or modified, including any additional descriptive specifications and information not included in a separate specifications document; and. It is intended that this Design Guidelines document be used with professional judgment and experience in the design of drinking-water systems … This allows easier access during the winter as the immediate area around the elevated manhole is often blown clear of snow. The design of such a system should minimize the length of pipe required and, in turn, minimize energy losses. The designer should be specifically aware that problems can arise when frost depth penetration values are applied without an adequate factor of safety in an effort to minimize the high cost of excavation and hence watermain installation costs where watermains are installed in trenches blasted in rock or areas with high water level conditions.