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1 Subsurface Erploration and <br /> 2026 Grarrd.ivem�e Geotechnica!Engineenng Report <br /> � E��erett LVnshinetai Design Recommendations <br /> I Fully resr.rained, horizontally backtilled �valis that cannot yield shouid be designed for an <br /> equivalent fluid of 60 pcf. <br /> I The lateral pressures presenred abovc arc based on :he conditions of a uniform backfill <br /> :unsisting of an-site saud and gravel �ill compacted te '10 perceni of ASTM:D 1557, with 12 <br /> inches of washed drain rock inunediately adjacent to Uie wall. A Iiigher degree of compaction <br /> � is nut recotnmended, as this will increase the pressure acting on the wall. A lower compaction <br /> , m:ry result in setdement behind thc wall. In lieu of placing a �ravel drain, a suitable composite <br /> drainboc,rd can be used �gains[ the wall. <br /> I10.1 Passive Resistance and Friction Pactors <br /> i Retainine wall footings/keyways cast directly upon undisturbed, dense sand soils may be <br /> d�signed (or passive resistance against lateral translation using an equivalent fluid equal to Z50 <br /> I pcf. The passive equivalent fluid pressure diacram begins at thc ground surface; however, <br /> lateral resistance should be ignored in the upper 18 inches of soil (truncated triangular <br /> diagram). The passivr, resistance value includes a factor of safety equal ro 3, in order w <br /> � reduce dic amount of movement nccessary to generate passive resistance. <br /> The friction coefficient for footings cas, direcdy on undismrbed, medium dense to dense, <br /> i r,ative soils n:ay n,. r;,,tNn a� fl.JO. �n e�cavatnr eyuipoed with a smooth plate ott the bucAet <br /> must be utilized to limit disturbance to thesc soil�. <br /> � <br /> � l 1 A PLOOR SUPPORT' <br /> � Slab-on-grade construction ���oul� q�picall}� be uscd for the basement garage floor. Preparation <br /> for iloor slabs should be as discussed in die Site Prepm-ntion section of chis report. Any fill <br /> beneath slabs should be compacted to at least 92 percent of ASTbt:D 1557 (modified Proctor). <br /> ITo control moiswre migration from bcneath the slab, the subgrade should be covered with 4 <br /> inches of pea gravcl to act as a capillary break. The pea gravel should then be covered by a <br /> � moismre barrier for Floor slabs. To protect the muisture barrier and to allow escess water to <br /> � dissipate from Uie slab durine finishing and curing. a 2-inch-thick layer of sand over the vapor <br /> barrier may bc use�. <br /> 12.0 DRAINAGG CONSID6RATIONS <br /> IAll perinteter foun�ation ���alls shuuld be provided with a drain at the footing base elevation: <br /> Drains should consist o( ricid, d-indrdiameter, perforated PVC pipe covered by at least 6 <br /> I inches of pca gravel. The bottom of the pipe should be set approximately 2 inches below the <br /> buttom of the foundation and should be constructed �vith sufficient gradient to allow gravity <br /> �ischargc away from the buildines. Ruof and surface runoff must not discharge into the <br /> 1 <br /> ������ �9 �� . ASSOCIATED L•.aRTH SCIFNCES, l��'C. <br /> ( i.cs.e„ -ntcn�rur,t -�nm�m,e.a�-�rx PagC 11 <br /> � <br />