6301 36TH AVE W 2016-11-01 - Laserfiche WebLink

' June 23,2014 Project No.T-6241 ' The capillary break layer will not prevent moisture intrusion through the slab caused by water vapor transmission. Where moisture by vapor transmission is undesirable, such as covered floor areas, a common ' practice is to place a durable plastic membrane on the capillary break layer and then cover the membrane with a layer of clean sand or fine gravel to protect it from damage during construction, and aid in uniform curing of the concrete slab. It should be noted that if the sand or gravel layer overlying the membrane is saturated prior to ' pouring the slab, it will be ineffective in assisting uniform curing of the slab, and can actually serve as a water supply for moisture seeping through the slab with potential for adverse impacts to floor coverings. Therefore, in our opinion, covering the membrane with a layer of sand or gravel should be avoided if floor slab construction ' occurs during the wet winter months and the layer cannot be effectively drained. We recommend floor designers and contractors refer to the 2003 American Concrete Institute(ACI)Manual of Concrete Practice,Part 2.302.1 R- 96, for further information regarding vapor barrier installation below slab-on-grade floors. ' 5.7 Lateral Earth Pressures for Below-Grade Walls ' The magnitude of earth pressure development on below-grade walls will partly depend on the quality of the wall backfill. We recommend placing and compacting wall backfill as structural fill as described in Section 5.2 of this report. To guard against hydrostatic pressure development, wall drainage must also be installed. A typical ' recommended wall drainage detail is shown on Figure 4. With wall backfill placed and compacted as recommended, and drainage properly installed, we recommend ' designing unrestrained walls for an active earth pressure equivalent to a fluid weighing 35 pounds per cubic foot (pcf). For restrained walls, an additional uniform load of 100 psf should be added to the 35pcf. To account for typical traffic surcharge loading, the walls can be designed for an additional imaginary height of two feet (two- foot soil surcharge). For evaluation of wall performance under seismic loading, a uniform pressure equivalent to 8H psf, where H is the height of the below-grade portion of the wall should be applied in addition to the static lateral earth pressure. These values assume a horizontal backfill condition and that no other surcharge loading, ' sloping embankments, or adjacent buildings will act on the wall. If such conditions exist, then the imposed loading must be included in the wall design. Friction at the base of foundations and passive earth pressure will provide resistance to these lateral loads. Values for these parameters are provided in Section 5.5 of this report. 5.8 Site Retaining Walls ' The vertical grade transitions along the north property line and the southern edge of the pond berm will be supported using site retaining walls. There is an approximately 8-foot tall rockery planned at the northwest corner of the parking lot north of Building A. The wall will support fill material used to establish parking lot t grades. As we understand,mechanically stabilized earth(MSE) walls constructed using Lock+Load panels are being considered to support the grade for the access roadway to the north with a gravity wall constructed with precast Ultra Block units being considered to construct the south wall in the detention pond. ' We completed a design for MSE walls faced with Lock + Load panels and rockery construction. Our designs address internal and external wall stability considerations and were completed using the computer program MSEW v.3.0 published by ADAMA Engineering, Inc. All analyses yielded acceptable factors of safety for both static and seismic cases. Details showing MSE walls faced with Rockery construction and Lock+ Load panels for varying wall heights are shown on Figures 5 and 6,respectively. Page No. 10