3214 BROADWAY BROADWAY KINECT APARTMENTS 2021-08-11

CITY OF EVERETT STORMWATER MANAGEMENT MANUAL 1111 16. Materials specifications for any permanent piped system are listed in the City's DCSS, and shall be approved by the City. 4111 Maintenance Standards 1. Check inlet and outlet points regularly,especially after storms. 2. The inlet should be free of undercutting, and no water should be going around the point of entry. If there are problems,the headwall should be reinforced with compacted earth or sand bags. 3. The outlet point should be free of erosion and installed with appropriate outlet protection. 4. For permanent installations, inspect pipe periodically for vandalism and physical distress such as • slides and wind-throw. • 5. Normally the pipe slope is so steep that clogging is not a problem with smooth wall pipe, S however, debris may become lodged in the pipe. 3.3.6 SNIP C205: Subsurface Drains • Purpose • • To intercept, collect,and convey groundwater to a satisfactory outlet,using a perforated pipe or conduit below the ground surface. Subsurface drains are also known as "french drains." The perforated pipe provides a dewatering mechanism to drain excessively wet soils,provide a stable base for construction, • improve stability of structures with shallow foundations, or to reduce hydrostatic pressure to improve • slope stability. Conditions of Use S Use when excessive water must be removed from the soil. The soil permeability, depth to water table and • impervious layers are all factors which may govern the use of subsurface drains. • Relief drains are used either to lower the water table in large,relatively flat areas, improve the growth of at vegetation, or to remove surface water. They are installed along a slope and drain in the direction of the • slope,and can be installed in a grid pattern, a herringbone pattern, or a random pattern. - Interceptor drains are used to remove excess groundwater from a slope, stabilize steep slopes,and lower the water table immediately below a slope to prevent the soil from becoming saturated. They are installed perpendicular to a slope and drain to the side of the slope and usually consist of a single pipe or series of • single pipes instead of a patterned layout. • Design and Installation Specifications ID Depth and spacing of interceptor drains I. The depth of an interceptor drain is determined primarily by the depth to which the water table is • to be lowered or the depth to a confining layer. For practical reasons,the maximum depth is usually limited to 6 feet, with a minimum cover of 2 feet to protect the conduit. • 2. The soil should have depth and sufficient permeability to permit installation of an effective • drainage system at a depth of 2 to 6 feet. 3. An adequate outlet for the drainage system must be available either by gravity or by pumping. 4. The quantity and quality of discharge needs to be accounted for in the receiving stream • (additional detention may be required). - 5. This standard does not apply to subsurface drains for building foundations or deep excavations. • ID Volume it—Construction Stormwater Pollution Prevention • 3-43