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4.6.4.Asphalt-Treated Base <br /> If pavements are constructed during the wet season, consideration may be given to covering the areas to <br /> be paved with asphalt-treated base(ATB)for protection. Light-duty pavement areas should be surfaced with <br /> 3 inches of ATB, and heavy-duty pavement areas should be surfaced with 6 inches of ATB. ATB placed to <br /> support construction equipment and heavy construction loads should also be at least 6 inches thick, but <br /> should be evaluated by the contractor if thicker sections are needed. Prior to placement of the final <br /> pavement sections, we recommend the ATB surface be evaluated and areas of ATB pavement failure be <br /> removed, and the subgrade repaired. If ATB is used and is serviceable when final pavements are <br /> constructed,the CSBC can be eliminated, and the design PCC or asphalt concrete pavement thickness can <br /> be placed directly over the ATB. <br /> 4.7. Earthwork <br /> 4.7.1. Clearing and Site Preparation <br /> Construction of the building addition will require demolii o of existing struul ns,asphalt pavement, curbs, <br /> and utilities. Concrete rubble and asphalt pavem. nt retrieved from demolition activities may be recycled <br /> and reused as structural fill, otherwise it should be removed from the site alori, ,vith other construction <br /> debris. Based on our explorations and site observation , the asrin li pavement is i.\;✓pically 2 to 3 inches <br /> thick.All existing utilities should be remo' 'd from the build, ''run footprint and be r: routed if needed. <br /> 4.7.2.Subgrade Preparation <br /> Prior to placing structural fill to support on-t;o de flou, ahs, founda i, ns or pavement, subgrade areas <br /> should be evaluated by n{oia;:i and perforrnu g a proof. II 'as needo.-1) to locate any soft soils. All <br /> unsuitable soils should 1 Jrnoved h om below k d1Idirt, plJition I'i_;,rndation areas prior to the evaluation. <br /> The exposed foundatic,° :_;l..ibgrade arods should bn p f:,aed to determine the extent of loose fill or other <br /> unsuitable soils, while ner slab-on-g, ple and paverr'nt subgrade areas should be proof-rolled with a <br /> loaded dump truck or equival r If loose fill or pumpingt soils are observed they should be removed and <br /> replaced v ..i fill. <br /> After col; ting the evaluation,the subgrade areas should be recompacted to a firm condition, if possible. <br /> The degree o compaction that : in be acid v d will depend on when the construction is performed. If the <br /> work is perforrl during dry weal:,or conditini 1s, we recommend that all subgrade areas be recompacted <br /> to at least 95 perc :r.t of the MDD i ooccordance with the ASTM D 1557 test procedure (modified Proctor). <br /> If the work is performed during wet ;<oather conditions, it may not be possible to re-compact the subgrade <br /> to 95 percent of the ML)+ In thi -ase, we recommend that the subgrade be compacted to the extent <br /> possible without causing ur, n o aving or pumping of the subgrade soils. <br /> Subgrade disturbance or deterioration could occur if the subgrade is wet and cannot be dried. If the <br /> subgrade deteriorates during compaction, it may become necessary to modify the compaction criteria or <br /> methods. It may also be necessary to place crushed gravel to protect the floor slab subgrade areas during <br /> construction. <br /> GEOENGINEERS� December 6,2021 Page 8 <br /> File No.24459-003-00 <br />