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CITY OF SANTA ANA <br />Planning and Building Agency <br />April 16, 2025 Project Number 25129-25 <br />Page 16 Approved <br />FOR PERMIT ISSUANCE <br />• Drainage away from structures and pavement is essential to prevent excessive <br />wetting of expansive soils. Grades should be designed to the la (Mb11aHdfing code <br />and maintained to allow flow of irrigation and rainwater to approve drainage devices <br />or to the street. Any "ponding" of water adjacent to buildings, slabs and pavement <br />after rains is evidence of poor drainage; the installation of drainage devices or <br />regrading of the area may be required to assure proper drainage. The installation of <br />rain gutters is also recommended to control the introduction of moisture next to <br />buildings. Gutters should discharge into a drainage device or onto pavement which <br />drains to roadways. <br />• Irrigation should be strictly controlled around building foundations, slabs and <br />pavement and may need to be adjusted depending upon the season. This control is <br />essential to maintain a relatively uniform moisture content in the expansive soils and <br />to prevent swelling and contracting. Over -watering adjacent to improvements may <br />result in damage to those improvements. NorCal Engineering makes no specific <br />recommendations regarding landscape irrigation schedules. <br />• Planting schemes for landscaping around structures and pavement should be <br />analyzed carefully. Plants (including sod) requiring high amounts of water may result <br />in excessive wetting of soils. Trees and large shrubs may actually extract moisture <br />from the expansive soils, thus causing contraction of the fine-grained soils. <br />• Thickened edges on exterior slabs will assist in keeping excessive moisture from <br />entering directly beneath the concrete. A six-inch thick or greater deepened edge on <br />slabs may be considered. Underlying interior and exterior slabs with 6 to 12 inches <br />or more of non -expansive soils and providing presaturation of the underlying clayey <br />soils as recommended in the soil report will improve the overall performance of on - <br />grade slabs. <br />NorCal Engineering <br />