2026 GRAND AVE 2016-01-01 MF Import

i � Subsurface Fxplo�tion and 2026 Grand Avenue Georechnical Engineenng Reporr E�ererr tUashineton Design Recommendationr Fullv restrained, horizontally backfilled walls that cannot yield should be designed for an equivalent fluid of 60 pcf. The lateral pressures presented above are based on the conditions of a uniform backfill consistine of on-site sand and eravel fill compacted to 90 percent of ASTM:D 1557, with 12 inches of washed drain rock immediately adjacent to the wall. A hieher degree of compaction is not recommended, as this �vill inerease the pressure acting on the wall. A lower compaction may result in setdement behind the wail. In lieu of placine a gravel drain, a suicable composite drainboard can be used against the wall. 10.1 Passive Resistance and Friction Factors Retaining wall footingslkeyways cast direcdy upon undisturbed, dense sand soils may be designed for passive resistance aeainst lateral translation using an equivalent fluid equal to 250 ocf. The passive equivalent fluid pressure diagram beeins at the ground surface; however, lateral resistance should be ignored in the upper 18 inches of soil (truncated triangular diagram). The passive resistance value includes a factor of safety equal to 3, in order to reduce the amount of movement necessary to generate passive resistance. The friction coefficient for footings cast directly on undisturbed, medium dense to dense, native soils may be taken as 0.40. An excavator equipped with a smooth plate on the bucket must be utilized to lirnit disturbance to these soils. 11.0 FLGOR SUPPORT Slab-on-grade construction would typically be used for the basement garage floor. Preparation for floor slabs should be as discussed in the Site Preparation section of this report. Any fill beneath slabs should be compacted to a� least 92 percent of .4STM:D 1557 (modified Proctor). To control moismre migration from beneath the slab, the subgrade should be covered with 4 inches of pea gra��el to act as a capiltary break. The pea gravel should then be covered by a moisture barrier for floor slabs. To protect the moisture barrier and to allow excess water to dissipate from tlie slab during finishine and curing, a 2-inch-thick layer of sand over the vapor barrier may be used. � 12.0 DRr11NAGE CONSIDEEtr1T[ONS All perimeter foundation walls should be provided with a drain at the footing base elevation: �rains should consist of rigid, 4-inch-diameter, perforated PVC pipe covered by at least F inches of pea eraveL The bottom of the pipe should be set approximately 2 inches belo�v the bottom of the foundation and should be constructed with sufficient eradient to allow gravity discharge away from the buildings. Roof and surface runoff must not discharge into ihe J�v�e 19, 2000 EXHIBIT i� ASSCCI.ITEDEARTHSClENCES, /NC. i+s,m-r:�a»roc� -r�oc:�ece-w_n �F�LQF /9 Page11