CITY PROJECT - 1821 & 1823 E Chestnut Ave - Plan

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ASSOCIATED SOILS ENGINEERING, INC. Project No.: 7160.23 2860 Walnut Avenue, Signal Hill CA 90755 January 23, 2024 Tel: (562) 426 -7990 * Fax: (562) 426 -1842 Page 20 respectively, as shown in Figure 5, Nearby Building Surcharge Consideration and Retaining Wall Drainage Details. Any retaining wall with a retained height exceeding six (6) feet should additionally be designed to resist seismic lateral earth pressure. The Geotechnical Consultant should be consulted if this condition exists, or if the local governing agency requires the retaining wall to be designed for seismic lateral earth pressure regardless of the retained height. Footings should be reinforced as recommended to by Structural Consultant. Appropriate back drainage should be provided to avoid excessive build-up of hydrostatic wall pressures. Retaining Wall Design Parameter Value Allowable Soils Bearing Capacity 2,000 psf (1)(2) Active Pressure [site soils backfill: level] 40 pcf EFP (3) At-rest Pressure [site soils backfill: level] 60 pcf EFP (3) Passive Pressure (per foot of depth) 200 pcf EFP, subject to a ceiling value of 2,000 psf(4) Coefficient of Friction 0.35 (4) Minimum Footing Depth 18 inches Minimum Footing Width 15 inches Minimum Reinforcement Four No. 4 rebar - 2 near top and 2 near bottom (1) Based on compliance with earthwork recommendations per Section 5.2 of this Soils Report. (2) Allowable soils bearing capacity increase for larger retaining wall footings should be as per Section 5.3.2 b). (3) Design values assuming a drained condition with “Very Low” to “Low” expansive materials (EI ≤ 35) within the backfill zone and no surcharge loading conditions. (4) Passive lateral resistance may be combined with frictional resistance provided the passive lateral earth pressure is reduced by 1/3. See Section 5.3.1c. The Geotechnical Consultant should be on-site during temporary back cut and retaining wall construction to inspect and evaluate the stability of cuts and, if necessary, to provide additional remedial or mitigative recommendations. Preferably, the backfill should consist of approved “Very Low” expansive material (i.e. EI ≤ 20) and should be compacted to a minimum relative compaction of 90 percent. The width of the “Very Low” expansive backfill zone should be a minimum of one (1) foot measured from the rear side of the stem of the retaining wall, or the space between the rear side of the stem and the heel of the retaining wall, or one-half (1/2) of the retained height of the retaining wall, whichever is greater. Flooding or jetting of backfill should not be permitted. Granular backfill should be capped with 18 inches (minimum) of relatively impervious fill to seal the backfill and prevent saturation. Figure 5 illustrates the general configuration and requirements for retaining wall drainage. Should any conflict noticed between recommendations stated in this report and those shown in Figure 5, the fore should govern. Other retaining wall drainage alternatives such as CONTECH C-Drain or