1110 RAINIER AVE A DOMESTIC VIOLENCE SERVICES OF SNO CO 2018-01-01 MF Import

� Evcrett Housir,g Authority May 16. 2012 � JN 12080 Page 9 although the manufaclurers of the admixtures should be consulted. Where vapor retarders are used under slabs, iheir edges should overlap by at least 6 inches and be sealed with adhesive tape. The sheeting should extend io the foundalion walls for maximum vapor prolection. If no potential for vapor passage ihrough the slab is desired, a vapor barrier shouid be used. A vapor barrier, as defined by ACI, is a product with a water transmission rate of 0.01 perms when tested in accordance with ASTNt E 96. Reinforced membranes having sealed overlaps can meet this requirement. In the recent past, ACI (Section 4.1.5) recommended that a minimum of 4 inches of well-graded compactable granular material, such as a 5l8-inch-minus crushed rock pavement base, be placed over the vapor retarder or barrier for iheir protection, and as a"blotler" to aid in the curing of the concrete slab. Sand v�as not recommended by ACI for this purpose. However, the use of material over the vapor retarder is controversial as noted in current ACI literalure because oF the potential that the protectionlblolter material can become wet belween the time of its placement and the insfallation of Ihe slab. If the material is �vel prior to slab placement, which is always possible in the Puget Sound area, it could cause vapor transmission to occur up through the slab in the future, essentially destroying the purpose of the vapor barrier/retarder. Therefore, If there is a potential that the proiectionlblotter materia! will become wet before the slab is instatied, ACI no�v recommends ihat no protertionlblotter material be used. However, ACI then recommends that, because there is a uutenlial (or siab cure due to the loss of the blotter material, joint spacing in the siab bP re�uced, a low shrinkage c.oncrete mixture be used, and "other measures" (steel reinforcing, etc.) be used. ASTM E-1643-98 "Standard Practice for Installation of Water Vapor Retarders Used in Contact �vith Earth or Granular Fill Under Concrete Slabs" generaliy agrees with the recent ACI literetu�e. We recommend that the contractor, ihe project materials engineer, and the owner discuss these issues and review recent ACI titerature and ASTIv1 E-1643 for installation guidelines and guidance on the use of the prolectionlblotter material. The Generel, Permanent Foundation and Retaining Walfs, and Drainage Considcrations sections should be •eviewed for additional recommendations related to the conlrol of groundwater and excess water vapor for the anticipated construction. EXCAVATIONS AND SLOPES No excavaled slopes are anticipated olher than for utility trenches. Excavation slopes should nol exceed the limits specified in local, state, and nafional governmenl safety regulations. Temporary cuts to a deplh of about 4 feet may be attempted verticaliy in unsaturated soil, if there are no indications of slope instability. However, vertical culs should not be made near property boundaries, or er.isting utilities and siructures. Based upon Washington Administrative Code (WAC) 296, Part N, lhe soil at the subject site would generally be classified as Type B. Therefure, temporary cut slopes greater than 4 feet in height should nol be excavaled at an Inclination steeper than 1:1 (Horizontal:Vertical), extending conlinuously benveen the top and the bottom of a cut. The above•recommended temporary siope inclination(s) is based on the conditions exposed in our explorations, and on what has been successful al other sites evith similar soil conditions. It is possible that variations in soil and groundwater condilions will require modifications to the ;nclination at �vhich temporary slopes can stand. Temporary cuts are those that will remain unsupporied for a relalively short duration to allow for the conslruction of foundalions, retaining walls, or utilities. Temporary cut s!opes should be protected wiih plaslic sheeting during wet GEOTECH CONSULTANTS,INC.