200 W MARINE VIEW DR BAYWOOD Geotech Report 2025-08-11

October 16, 2020 Project No. T-8221 I 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 I 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 in uniform curing of the slab and can actually serve as a water supply for moisture Itransmission through the slab and affecting 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 I layer cannot be effectively drained. We recommend floor designers and contractors refer to the American Concrete Institute(ACI)Manual of Concrete Practice,for further information regarding vapor barrier installation below slab- on-grade floors. ' A subgrade modulus (ks) if 100 pounds per square inch per inch of deflection (pci) can be used for design of the I industrial slab on grade floor. 1 5.6 Lateral Earth Pressures The magnitude of earth pressure development on building retaining walls, and walls constructed in loading dock I areas will partly depend on the quality of wall backfill. We recommend placing and compacting wall backfill as structural fill. To guard against the build-up of hydrostatic pressure, wall drainage must also be installed. We recommend that wall drainage consist of a minimum 12-inch thick layer of washed rock or pea gravel placed adjacent to the wall. Alternatively, a composite drainage panel such as Mirafi G100N or equal can be used. For both wall and foundation drains,a four-inch diameter perforated pipe should be placed on a bed of gravel along the I base of the footing and directed to a suitable outlet. The recommended wall drainage is shown on the Typical Wall Drainage Detail, Figure 4. I With granular backfill placed and compacted as recommended and drainage properly installed, we recommend designing restrained(not free to deflect)retaining walls for an at-rest earth pressure equivalent to a fluid weighing I 50 pcf. A value of 35 pcf may be used for the case where the wall is unrestrained. An additional horizontal traffic surcharge value of 120 psf should be included in wall design for locations where semi-truck traffic will occur adjacent to the wall. This value may be reduced to 75 psf where traffic adjacent to the wall will consist of passenger I cars and light service trucks only. The above values do not include other surcharge loading such as from fill backslopes or adjacent footings that may Iact on the wall. If such conditions will exist,then the imposed loading must be included in wall design. Values of friction at the base of wall foundations and passive earth pressure that are used in design to resist lateral loads are I provided in the Foundations Section. I IPage No. 8