introduCtion Medicine Hat The City of Medicine Hat addresses site development or redevelopment on a site by site according to its Municipal Servicing Standards, and under certain circumstances may require stormwater quality treatment by the provision of a high flow bypass oil grit separator or approved equivalent treatment system. The City further recommends, “the Designer should contact the Municipal Engineering Department of the city to determine if a specific oil/grit separator type system is acceptable for the specific conditions of a site. If on-site detention is also required, such detention storage shall be provided upstream of the oil/ grit separator. Manufactures’ guidelines are to be followed for any specific oil/grit separator. All sizing and design information shall be provided with the detailed engineering plans” ConCrete pipe Red Deer Red Deer’s Stormwater Management Standards state the following with respect to requirements for stormwater treatment units: Purpose Storm Water Treatment Units are a variation of traditional settling tanks. They are designed to capture sediment suspended in stormwater runoff as the runoff is conveyed through a storm sewer system. The unit is a below ground structure that takes the place of a conventional manhole or catch basin in a storm sewer system. The unit uses a permanent pool of water in the removal of sediment from stormwater run-off before discharging into the receiving water body. Design Criteria Alberta Environment Protection guidelines state “Treatment units are to be sized based on a minimum treatment flow rate of 75 l/s per hectare of development area and must be capable of conveying at least 150 1/s per hectare of flow through the treatment unit without re-suspending sediments or floatable materials within the treatment unit. The treatment unit shall remove at least 85% of all sediments of a 75-micrometer particle size or larger.” stormwater treatment teChnologies box seCtions manhole and CatCh basin material LAFARGE PIPE eMANUAL PAGE 43