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 21 MIRADRAIN may be considered but should first be reviewed and approved by the Geotechnical Consultant prior to implementation. Should the space behind the new retaining wall be too tight to implement the above recommended backfill effort, as an alternative, 2-sack control density fill (slurry fill) may be used in lieu of regular soil backfill, provided that the integrity and functionality of wall backdrain is protected and maintained. It should be noted that the use of heavy compaction equipment in close proximity to retaining structures can result in wall pressures exceeding design values and corresponding wall movement greater than that normally associated with the development of active or at-rest conditions. In this regard, the contractor should take appropriate precautions during the backfill placement. 5.3.3 Footing/Foundation Observation: All footing/foundation excavations should be observed by the Geotechnical Consultant's representative to verify minimum embedment depths and competency of bearing soils. Such observations should be made prior to placement of any reinforcing steel or concrete. 5.4 Slabs-On-Grade For structural design of concrete slabs, a modulus of subgrade reaction ("k-value") on the order of 100 pounds per square inch per inch ("psi/in") and an allowable bearing capacity of 850 psf may be used for slab constructed on recompacted site soils. Interior and exterior slabs should be properly designed and reinforced for the construction and service loading conditions. To minimize static slab distress, geotechnically, it would be prudent to provide minimum actual slab thickness of four (4) inches with minimum reinforcements consisting of number 4 reinforcing bars spaced maximum 12 inches on centers each way, placed at mid-slab, for exterior slabs and Building interior slab-on-grade, when supported by compacted fill. The final structural details, such as slab thickness, concrete strength, amount and type of reinforcements, joint spacing, etc., should be established by the Structural Consultant in accordance with pertinent sections in 2022 CBC. The entirety of any new slabs within the Building should be underlain by an impermeable vapor barrier (minimum 15-mil-thick visqueen). A minimum 12-inch overlap between visqueen sheets should be ensured during placement. All visqueen sheets should be puncture free prior to slab construction, and should be sandwiched top and bottom by two (2) inches of clean sand (Sand Equivalent (SE) ≥ 30 per ASTM D2419-22 Test Method). Alternatively, as per stipulations in Section 5.2.3.2 of ACI 302.1R-15, for slabs in moisture- sensitive areas, the concrete slabs should be poured directly on a moisture barrier consisting of 15-mil Stego Wrap Vapor Barrier/Retarder that is in turn underlain by 4” of ½” to 3/8” open graded gravel or crushed rock complying with the criteria stipulated in Section 200-1.2 of the current Greenbook. The concrete slab shall consist of a concrete mix design which will address bleeding, shrinking and curling.