Laserfiche WebLink
4.0 RECOMMENDATIONS <br />4.1 Site Earthwork <br />We anticipate that earthwork at the site will consist of site preparation, demolition of existing buildings, <br />removal or abandonment of existing utilities crossing the site, and the removal of existing pavement <br />areas, followed by remedial removals and site grading followed by construction of slab -on -grade type <br />foundations for the proposed residential structures and parking structure, installation of utilities, <br />subsequently followed by paving/pouring of driveways and streets. <br />We recommend that earthwork onsite be performed in accordance with the recommendations herein, <br />the City of Santa Ana, and the General Earthwork and Grading Specifications for Rough Grading <br />included in Appendix E. In case of conflict, the recommendations in the following sections shall <br />supersede those included as part of Appendix E. <br />4.1.1 Site Preparation <br />Prior to grading of areas to receive structural fill or engineered structures, all ground surfaces <br />should be cleared of obstructions, any existing debris and stripped of vegetation. Heavy <br />vegetation and debris should be removed and properly disposed of offsite. All debris from any <br />demolition activities at the site should also be removed and disposed off -site. Holes or <br />depressions resulting from the removal of buried obstructions should be replaced with <br />compacted fill. <br />Following remedial removals, areas to receive fill should be scarified to a minimum depth of 12 <br />inches, brought to a near -optimum moisture condition, and recompacted to at least 90 percent <br />relative compaction (based on American Standard of Testing and Materials [ASTM] Test <br />Method D1557). <br />4.1.2 Removal and Recompaction <br />As discussed in Section 2.2, the upper portion of the site is underlain by potentially <br />compressible/collapsible or unsuitable soils (i.e. existing fills and younger alluvium), which <br />may settle under the addition of water, under the surcharge of fill and/or foundation loads. <br />Compressible materials not removed by the planned grading should be excavated to competent <br />material and replaced with compacted fill soils. We anticipate removals across the apartment <br />and townhome sites to be approximately 5 feet in depth below existing grade or a minimum of <br />3-feet below proposed residential buildings footing bottom elevations, and up to 10 feet below <br />existing grade, for the parking structure area, or a minimum of 3-feet below the parking <br />structure foundations, whichever is deeper, to remove unsuitable fills and alluvium; however, <br />other localized, deeper removals should be anticipated where deemed necessary by the <br />geotechnical consultant based on observations during grading. Removal bottoms should be <br />scarified to a minimum depth of 12 inches, brought to at least optimum -moisture content, and <br />recompacted. Compacted fills placed underlying the townhomes/apartment structures and <br />parking structure should be compacted to minimum relative compactions of 90 and 95 percent, <br />respectively. The fill prism beneath the building footings should extend downward at a 1:1 <br />(horizontal to vertical) slope from the outside edge of the footing bottoms. The removals <br />should extend a minimum of 5 feet beyond the building perimeters. In general, the intent of <br />the remedial removals is to remove all undocumented fills, and unsuitable alluvium. <br />Project i y ouncil 18 — 828 1 3 , 2021 <br />