(A) Compaction. Fill must be compacted throughout their full extent to a minimum of 90% of maximum density as determined by ASTM Soil Compaction Test D 1557-91, where applicable; where not applicable a test acceptable to the City Engineer or Building Official must be used. Field density must be determined by a method acceptable to the City Engineer or Building Official.
(1) Fill slopes steeper than two horizontal to one vertical must be constructed by the placement of soil a sufficient distance beyond the proposed finish slope to allow compaction equipment to operate at the outer surface limits of the final slope surface. The excess fill is to be removed prior to completion or rough grading. Other construction procedures may be utilized when it is first shown to the satisfaction of the City Engineer or Building Official that the angle of slope, construction method and other factors will accomplish the intent of this section.
(2) Fills not intended to support structures are not required to be compacted to these standards if the City Engineer or Building Official determines that such compaction is unnecessary as a safety measure. In making this determination, the City Engineer or Building Official may require that the owner provide a report from a soils engineer establishing the characteristics of the soil, the amount of settlement to be expected and the susceptibility of the soil to erosion or slippage.
(3) Slope surfaces may be prepared for planting by scarifying, by the addition of top soil, or by other methods, provided such slopes when so prepared otherwise comply with the requirements of this section.
(B) Preparation of ground. The existing ground surface must be prepared to receive fill by removing vegetation, noncomplying fill or other incompetent material. Where the slope of the existing ground surface is five horizontal to one vertical or steeper, the fill must be supported on level benches cut into competent material. The bench under the toe of a fill on a slope steeper than five to one must be at least ten feet wide. The area beyond the toe of fill must be sloped for sheet overflow or a paved drain must be provided. When fill is to be placed over a cut, the bench under the toe of fill must be at least ten feet wide, but the cut must be made before placing the fill and before acceptance by the geotechnical engineer or engineering geologist, or both if applicable, as a suitable foundation for fill. Daylight lines indicating a transition between fill and natural ground or fill and excavation are not allowed within the building area of a graded pad unless approved by the City Engineer or Building Official based on special circumstances or site conditions. Except where recommended by the geotechnical engineer or geologist as not being necessary and approved by the City Engineer or Building Official, subdrains must be provided under all fills placed in natural drainage courses and in other locations where seepage is evident. Such subdrainage systems must be of a material and design approved by the geotechnical engineer and acceptable to the City Engineer or Building Official. The permittee must provide continuous inspection during the process of subdrain installation to conform with approved plans and geotechnical engineer's recommendation. Such inspection must be done by the soil testing agency. The location of the subdrains must be shown on a plan by the geotechnical engineer. Excavations for the subdrains must be inspected by the geologist when such subdrains are included in the recommendations of the geologist.
(C) Fill slope. The City Engineer or Building Official may allow a slope of steeper than 2:1 for special circumstances or site conditions. The steepness of fill slopes must be determined by a soil engineer who must submit soil test data and engineering calculations to substantiate to the satisfaction of the City Engineer or Building Official the stability of the fill slope and slope surface under conditions of saturation.
(D) Fill material. Detrimental amounts of organic material are not permitted in fills. Soil containing small amounts of roots may be allowed if the roots are in a quantity and distributed in a manner that is not detrimental to the future use of the site, and the use of the material is approved by the soil engineer and the City Engineer or Building Official. No rock or similar irreducible materials with a maximum dimension greater than 12 inches can be buried or placed in fills except as recommended by the soil engineer, approved by the City Engineer or Building Official and meeting the following requirements:
(1) The oversized material must be placed ten feet or more below finish grade;
(2) A representative of the soil engineer must be present while the oversized material is placed and covered;
(3) The reports submitted by the soil engineer must acknowledge the placement of the oversized material and whether the work performed is in accordance with his or her recommendations and the approved plans; and
(4) The location of oversized rock dispersal areas must be shown on the as-built plan.
(5) Stockpiled soil, sand or gravel must be covered or stabilized as to prevent erosion by wind or water.
(E) Drainage. Drainage, including drainage terraces and overflow protection, must be provided as required by Chapter 16.99 of this Title 16.
(F) Slopes to receive fill. Where fill is to be placed above the top of an existing slope steeper than three horizontal to one vertical, the toe of the fill must be set back from the top edge of the slope a minimum distance of six feet measured horizontally or such other distance as may be specifically recommended by a soil engineer or engineering geologist and approved by the City Engineer or Building Official. Fills must not toe out on slopes steeper than two horizontal to one vertical.
(G) Inspection of fill. For engineered grading, the soil engineer must provide sufficient inspections during the preparation of the natural ground and the placement of compaction of the fill to be satisfied that the work is being performed in accordance with the conditions of plan approval and the appropriate requirements of this Code. In addition to the above, the soil engineer must be present during the entire fill placement and compaction of fills that will exceed a vertical height or depth of 30 feet or result in a slope surface steeper than two horizontal to one vertical.
(H) Testing of fills. Sufficient tests of the fill soils must be made to determine the density thereof and to verify compliance of the soil properties with the design requirements, including soil types and shear strengths in accordance with the standards established by the City Engineer or Building Official. The results of such testing must be included in the report required by this chapter.
(Ord. 1103, passed 3-7-05)