2232 12TH ST 2016-01-01 MF Import

ra rett Land Association F,-2554 ,druary 27, 19tl5 Paye 5 p/ Slab-on-•Grade Nloors Slab-on-grade fla�rs inay oe supporrea c�n tne com��etent native soil sub�rade or on ' structural [ili . At least one foor of structural Tiil snouid be placed belu•d slaos bearing on existing fill soils. Any disturbed native soils must either be recompacted or re��laced with sCruct�iral fill . The slab should be prc�vidad with a minimwn of fow- inches o[ free draininq sand oc- ,�ravel. t9e also recommend that a vapor barrier such �s a 6 inil plastic membrane sho�ld Ge placed beneath thc� slab Lo reduce waCer vapor transmission throuyh the slab and the resultant moistura accumulation. Two inches of sand may be placed over the membrane for protection during construction and to aid in curing of the concrete. Retaininq� and Foundation Walls Retaining and f�undation �:alls slnuld be iic�siyned Cn resist lateral earth pressures iinposed by t.he s�ils ret�ined l�y these structures . Walls that are designed to yield an amount equal to at least 0. 002 times the wall h�ight can be desiyned to resist tlie lateral earth pressure imposed by an equivalent f.lui�9 with a unit weight of thirty ( 3U) pcf. If walls are to be restrained at the top from free inovement, a uniform for.ce of one hundred ( lU0 ) F.sf should be added to the eguivalent fluid pressure force. For calculating the base resistance to slidiny, we recommend usiny a passive pressure eyuivalent to thal exerted by a fluid liaviny a density of three hundred fifty ( 35u ) pcf and a coefficiant of friction of U. 35. The wall pressures a�ply only for a maximum wall height of five feet. It is assumed that no hydrostatic pressures act behind the wall and that no surcharge slopes or loads will be placed above the walls. If surcharyes are to be applied tliey should be added to the above lateral pressures . � Retaining and foundation walls should be backEilled with compacted free-draining soils with no organics, as shown on Plate 7. The soil should contain no mor.e than 5 percent silt or clay and no particles greater than four inches in diameter. The ��ercenta,3e of particles passing the No.. 4 sieve should be between 25 an� 70 percent . Alternatively, a geotextile product such as Miradr�.in may be used. We recommend the use of footiny drains at r,he base ef all perimeter footings. The footinq drains should be surrounded by at least six inches of one inch minus washed rock, .�nd provided with a positive gradient towards suitable discharge facilities. The pipe invert should be at least as low as the ' t>ottom of the footing. For retaining walls, other than basement Nalls, weepholes can be used. The weepholes should be as low as possible to maintain drainage behind the walls. When weepholes are provided, all backfill within eighteen ( 18 ) inches of tlie weephole should consist of one inch minus washed rock . Earth Consultants, Inc .�.�,.-,�......e� �— -