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neild/[bbb 15:27 q257q78561 GEDTECH <br /> � ' � PAGE 09 <br /> Lucla Development LLC <br /> August 18, 2005 JN 05233 <br /> Page 8 <br /> as determined 6y ASTM E 96. It is possible that concrete admixtures may meet this spedficaUon, <br /> aithough the manufacturers oi the admixt�ares should Ce consuRed. Where plastic sheeting is used <br /> under slabs, joints should overfap by at least 6 lnches and be sealed with adhesive tape. Tha <br /> sheeting should extend to ihe foundation walls for m�cimum vapor protection. If no pofenttai for <br /> vapor passage through the slab is desired, a vapor b�vrier should be used. A vapor barrier, as <br /> . defined by ACI, is a product wiU1 a water transmisslon r�te of 0.00 pertns per square foot per hour <br /> when tested (n accordance with ASTM E 96. Reinforced membranes having sealed overiaps can <br /> meet thfs requirement. <br /> In the I�cent past, ACI (Section 4.1.b) recornmended that a mfnimum of 4 inches of well-graded <br /> �mpactable granular materfal, such as a 5/8 tnch minus crushed rock pavemant bese, should be <br /> placed over U1e vapor retarcler or batrier for protection of!he retafder or barrier and es a �lofter"to <br /> aid in the curing of the concrete slab. 5and was not recommended by AC! for this purpose. <br /> Ho„vvever, the use of maierial over the vapor ret2rder is controversial as noted in ame;�t ACI <br /> literature because of the potential that the protectioNb(otter material can become wet belwee� the <br /> time of fts placement and the installation of the stab. If the material is wet prior to slab placemerrt, <br /> which !s always possible in the Pupet Sound area, it could cause vapor transmisslon to occur up <br /> through the slab in the future, esserttiaily destroyin8 the purpose of the vapor bartier/retarder. <br /> Therefore, ff therP is a patential that the protectioNblotter material will become wet before the s�ab <br /> is (nstalled, AC! r.ow recommends that no p�ctection/blotter material be used. However, ACI then <br /> recommends tha.t, bequse there is a poiential for slab cure due to the loss of the Diotter materiai, <br /> l�im spadng in the slab be reduced, a �oW shrinka8e concrete mixture be used, and "other <br /> m^as;!res" (steel reinforcing, etc.) be used. ASTM E-1643-98 "Standard Practice for Installation of <br /> Water Vapor Retarders Used in Contad with Earth or Gfanular FII Under Concrete Slabs" <br /> 9en�rally agrees rivith the recent ACI literature. <br /> VVe recommend that tfie cot�tractor� the project materials eng(neer, and the owner discuss these <br /> issues and reWew recent ACI literature and ASTM E-1643 for Installation guidelines and guidance <br /> on ti�e use of the protectioNblotter material. Ou� opinfon is that with impervious surtaces that aA <br /> means should be undertaken to reduce w8ter vapor ttansmiss3on. <br /> DCCAVA770NS AND SLOPES <br /> No excavated slopes ere antidpated other than for utility tre�ches. Excavation slopes should not <br /> exceed the limits specified in tocal, state, and national govemment safety regulations. Temporary <br /> cuts to a depth of about 4 feet may be attemptad vertically in unsaturated so(I, if there ere no <br /> indications of slope instabiliry. Hawever, vertical cuts should not be made near property <br /> boundaries, or existing utilities and structures. Sased upon Washington Administrative Code <br /> (WAC) 2gF, pan N, the soil at the subjed site would generaliy be dassffied as Type C. Thenefore, <br /> temporary cut slopes greater than 4 feet in height should not be excavatad at an inclination steeper <br /> than 1.5:1 (Horizontal:Vertical), extending continuously between the top and the t�ottom of a cut. <br /> The above-recommended temporary slope inclination is based on the conditions exposed in our <br /> explorations, and on whai has been successful at other sites with slmflar sofl condRions. It i" <br /> possible that variations in so(I and groundwater candiqons Will requfre modificatians to the <br /> fnclination at whi�h temporary slopes can stand. Temporary cuts are those that will remain <br /> unsupported for a relatively short duration to allow for the constnidlon of foundations, retaining <br /> walls, or utilities. Temporary cut slopes should be protecfed Wj� p�astic sheeting during wet <br /> weather. It is also important that surtace water be directed away from temporary slope cuts, The <br /> cut slopes should also k� backfilled or retafned as soon as possible to reduce the potential for <br /> GEOTECN CONSULTANTS,INC. � <br />