1130 RAINIER AVE WHOLE SITE DOCUMENTS 2016-01-01 MF Import

� Evereff Nousing Aufhority fvtay 16, 2012 � JN �2080 Page t0 weather. It is also important that surface water be directed away from temporary slope culs. The cut slopes should also be backfilled or retained as soon as possible to reduce the potential for instabdity. Ptease note that loose soil can cave suddenly and erithout v�arning. Excavation, foundation, and utiliry contractors shculd be made especi211y a�.v2re of this potential danger. These recommendations may need to be modified if the area near the potential cuts has been disturbed in 1he past by ulility instaliation, or if settlemenl-sensitive ulilities are located nearby. All permanent slopes shcuW be inclired no sleeper tnan 2:1 (H:V). Water should not be allo�.ved to i!o�v uncontrolled over the top of any temporary or permanent slope. All penn2nently exposecl slopes should Le seeded r:d!� an appropriale species of vege:aGon to reduce erosion and improve the stablity c( the surficia! leyer ot so�l. Tcpsoil is often piaced on regraded slopes to cromot� grcvltn of vec�etalioa. Proper preparat�or, of lhe regraded siir(ace, ard use of appro�ria:e topscil is necessary to preven` the topsoil from sliding otf the slope This is most likely to occur fo�losving e:dended avel weather if a sill9 topsoil is used. Un steeper slopes, it may be necessary ?o "track �.vaik" the slope or cut small grcoves across the slcpe prior to placing the topsoil. DRAINAGE CONSIDERATIONS Fcundation drains should be used where (1) cra�vl spaces or basements �.vili be belo�v a structure, (2) a slab is below the outside grade, or (3) the outside grade does not slooe dovrnward from a buiiding. Drains should also be placed at the base of all earth-retaining �valls. These dralns should be surrounded by at least 6 inches of 1-inch-minus, washed rock and lhen �vrapped in non-�voven, geotextile lilter fabric (tvlirafi 140N, Supac 4NP, or similar material). At its highest point, a perforated pipe invert should be at least 6 inches below lhe bottom of a siab floor or the level of a cra�vl space, and it should be sloped for drainage. All roof and sur(ace �vater drains must be kept separate from the foundation drain syslem. A typical drain detail is attached tc this report as Plate 9. For the best long-term performance, perforated PVC pipe is recommended for all subsurface drains. If the stnicture includes an elevator, it may be necessary to provide special drainage or �.vaterproofing measures for the elevator piL I( no seepage into the elevator pil is aceeplable, il will be necessary to provide a(ooling drain and free•draining wall backiill, and the �valls should be �vaterproofed. If the footing drain vriil be too low lo connect lo the storm drainage syslem, lhen it will Iikely be necessary to instail a pumped sump to discharge the collected watec Allematively, the eievator pit could be designed to be entireiy waterproo(; Ihis �vould include designing the pit structure to resist hydrostatic uplifl pressures. As a minimum, a vapor relarder, as defined in the Slabs-On-Grade seclion, should be provided in any crawl space area lo limil the transmission of water vapor from ihz underlying soils. Also, an outlel drain is recommended for all crawl spaces to prevent a build up oi any water thal may bypass the footing drains. The excavation and site should be graded so lhal sur(ace water is directed off the site and away from the tops of siopes. Water should not be allowed to stand in any area evhere foundations, slabs, or pavements are to be constructed. Final sile grading in areas adjaceN lo the building should slope away at least 2 percent, except where the area is paved. Surface drains should be provided �,vhere necessary to prevent ponding of �vater behind foundation or relaining �vaps. ceo�recH corasu�rn��,rs, m^