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

� EvereB Nousing Au(hority �tay 16. 2012 � JN 12080 Page 9 aithough the manufaclurers of the admixtures should be consulted. 4Vhere vapor retarders are used imder slabs, lheir edges should overlap by at least 6 inches and be seaied with adhesive tape. The sheeting should extend to the foundation v�alls for maximwn vapor protection. If ro potential for vapc- passage lhrough the slab is desired, a vapor barrier should be used. A vapor barrier, as defined by ACI, is a product wi�h a;vater transmission rale of 0.01 perms when tes:ed in accordance �vith AST�vt E 96. Reinforced membranes having sea!ed overiaps can meet Ihis requirement. In lhe recent past, ACI (Seclion 4.1.5) recemmended lhat a minimum of 4 inches of �n�ell-graded coinpactaole qranular malerial, such as a 5;6-inch-ininus crushed rock pavement base, be �laced cver ti�e vapor relardFr or barrier for their prolection, and as a"4lotter" to aid in If�e curir.g o` the concrete slab. Sand ti��as nol recommended by ACI `or ihis purpose. Hoav2ver, the use of m2terial over ihe vapor refarder is controversial as noted in current ACI lilerature because o( ihe ootenlial that the protection/blotter material can become wet be(�veen the time oi its placement and the inst211ation of Ihe slab. li the material is vuzt prior lo slab placement, which is al�:vays possibie in Ihe Puc�et Sound area, it couid cause vapor transmission to occur up through the slab in the fulure, essentially destroying the purpose of the vapor barrier/retarder. Therefore, I` there is a potential that the proteclion/blotter material �vill become evet Before lhe slab is installed, ACI now recommends ihat no protection/blolter material be used. Hovvever, ACI then recommends thal, because ihere is a potential for slab cure due to the loss of the blotler material, joint spacing in ihe slab be reduced, a low shrinkage concrete mixture be used, and "other measures" (steel reinforcing, etc.) be used. ASTti1 E-1643-98 "Standard Practice for Installation of Water Vapor Retarders Used in Contact witn Earih or Granular Fill Under Concrete SI2bs" generally agrees with the recent ACI Iiterature. We recommend thal lhe conlractor, the project materials engineer, and the owner discuss these issues and review recent ACI literature and ASTM E-1643 for installation guidelines and guidance on lhe use of the protection/blotter materiai. The General, Permanent Foundation and Retaininc� Walls, and Oreinage Considerations sections should be reviewed for additional recommendations related to the control of ground�vater and excess �vater vapor (or ihe anticipated constructien. EXCAVATIONS AND SLOPES No excavaled slopes are anticipaled other Ihan for ulility lrenches. Excavalion slopes should not exceed the limits specified in local, state, and national government sa(ety regulations. Temporary cuts to a depth o( about 4 feet may be attempted vertically in unsaturated soil, ii there are no indications of slope instability. However, vertical cuts should not be made near property boundaries, or existing utilities and siructures. Based upon Washington Adminisiralive Code (WAC) 296, Part N, ihe soil at the subject site would generally be classified as Type B. Therefore, temporary cut slopes greater than 4 feet in height should not be excavated at an Inclination steeper Ihan 1:1 (Horizontal:Vertical), extending continuously between the top and lhe boltom of a cut. The above-recommended temporary slope inclination(s) is based on the condilions exposed in our explorations, and on whal has been success(ul at other sites wilh similar soil conditions. It is possibie that variations in soil and groundwater conditions will require modificalions to the inclinalion at which temporary slopes can stand. Temporary cuts are those that wiil remain unsupported for a relatively short duration to allow for the consiruction of foundations, relaining walls, or utilities. Temporary cut slopes should be protected with plastic sheeting during wet GEOT"eCH CONSULTANTS,INC