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CITY OF SANTA ANA <br />Planning and Building Agency <br />April 16, 2025 Project N umber 25129-25 <br />Page 15 Approved <br />FOR PERMIT ISSUANCE <br />When expansive soils are compacted during site grading operations, care is iaken to place the <br />materials at or slightly above optimum moisture levels and perform p dpertemompaction <br />operations. Any subsequent excessive wetting and/or drying of expansive s Wwill cause the <br />soil materials to expand and/or contract. These actions are likely to cause distress o <br />foundations, structures, slabs -on -grade, sidewalks and pavement over the life of the structure. <br />It is therefore imperative that even after construction of improvements, the moisture <br />contents are maintained at relatively constant levels, allowing neither excessive wetting <br />or drying of soils. <br />Evidence of excessive wetting of expansive soils may be seen in concrete slabs, both interior <br />and exterior. Slabs may lift at construction joints producing a trip hazard or may crack from the <br />pressure of soil expansion. Wet clays in foundation areas may result in lifting of the structure <br />causing difficulty in the opening and closing of doors and windows, as well as cracking in <br />exterior and interior wall surfaces. In extreme wetting of soils to depth, settlement of the <br />structure may eventually result. Excessive wetting of soils in landscape areas adjacent to <br />concrete or asphaltic pavement areas may also result in expansion of soils beneath pavement <br />and resultant distress to the pavement surface. <br />Excessive drying of expansive soils is initially evidenced by cracking in the surface of the soils <br />due to contraction. Settlement of structures and on -grade slabs may also eventually result <br />along with problems in the operation of doors and windows. <br />Projects located in areas of expansive clay soils will be subject to more movement and "hairline" <br />cracking of walls and slabs than similar projects situated on non -expansive sandy soils. There <br />are, however, measures that developers and property owners may take to reduce the amount of <br />movement over the life the development. The following guidelines are provided to assist you in <br />both design and maintenance of projects on expansive soils: <br />NorCal Engineering <br />