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File: 218267 November 30, 2018 If a retaining wall is located on the downhill side of the pool (or spa),the retaining wall will need to be designed to resist lateral forces imparted by the pool (or spa) and any retained soils. Base-The base of the pool and spa need to be founded in dense native materials,as identified by our office in the field. Where the pool is shallower than 6 feet, the soils should be removed from the entire pool excavation area to that depth, then brought back up to the required depth using non- expansive compacted materials (e.g. baserock, drain rock, etc.). A minimum 4 inch thick layer of drain rock (3/4 inch clean crushed rock) should be placed along the base of the entire pool (and spa) excavation(s). A perforated pipe should be placed at the deep end of the pool to collect any water which drains into the rock. A solid discharge line should be connected to the perforated pipe and should carry collected water to a sump well. The sump should be fitted for a pump, but the pump does not need to be installed unless the pool is to be drained,or the water level in the sump is shallower than 2 feet below grade (in order to prevent the pool from becoming buoyant and popping out of the ground). In addition, a hydrostatic relief valve should be installed at the deep end of the pool. Decking-The decking around the pool(and spa)may consist of raised wood decking,concrete slabs- on-grade, or interlocking pavers. If concrete slabs are used, they should be constructed in a manner consistent with recommendations provided in the Slab-on-Grade section of this report. All decking should be structurally isolated from the pool and s a shells and the skimmer. This can be achieved through the use of full-depth expansion joints between the decking and pool coping. If it is desired to extend the decking over the edge of the pool shell (i.e. no coping stone), a horizontal expansion joint should be placed to completely separate the decking from the bond beam and coping tiles. Drainage Surface Drainage - Adjacent to any buildings, the ground surface should slope at least 5 percent away from the foundations within 5 feet of the perimeter. Impervious surfaces should have a minimum gradient of 2 percent away from the foundation. Surface water should be directed away from all buildings into drainage swales, or into a surface drainage system (i.e. catch basins and a solid drain line). "Trapped" planting areas should not be created next to any buildings without providing means for drainage (i.e. area drains). All new roof eaves should be lined with gutters. The downspouts may be connected to solid drain lines, or may discharge onto paved surfaces which drain away from the structure. The downspouts may be connected to the same drain line as any catch basins, but must not directly connect to any perforated pipe drainage system. Footing Drain - Due to the highly expansive soils, it will be required to install a perimeter footing drain to intercept water attempting to enter the crawlspace. Where the basement wall is at the perimeter of the house, it will serve as a perimeter footing drain system. 12