820 WAVERLY AVE 2018-01-02 MF Import

; � c H�rris•Tsang Architects E-4212 December 30, 1988 Page 3 ; � I I l While the native soils are competent in bearing, they are moderately to highly moisture � sensitive. Because of this they are susceptible to deterioration under construction tra�c � activiry during wet weather. Your contractor shonld be aware of this and should take precautions to protea the site subgrades. i � Since the site soils are essentially impermeable and moisture sensitive we belie.ve it is imponant that you include drainage control measures in both design and construction to help , ameliorate moisture related problems. i ' 1'hese items, and other geotechnicaliy-related aspecu of the project, are discussed in more detail in the fotlowing sections of this report. . ite Preparation and General Eanhwork . I The building and pavsment areas should be stripped of all tsphalt concrete overlay, organic matter and any other deleterious materials. We estimate that an average svipping depth of approximately eight inches will be required to remove the asphaltic materials and the immediately underlying granular base materials. Providing the base materials are relatively clean of organic or 5ne gra:ned soil they can be stockpiled for later use as a structural fill. The asphalt materials can be "lost" in landscaping areas providing it is broken into small pieces of no greater than six inches in maximum siu. If this cannot be accomplished, the materials should be removed from the site and disposed. Beneath the existing pavement is an approximately eighteen (18) inch thic;c layer of miscellaneous fill. It is probable that your contractor will need to overexcavate through this fill to reach the competent native soils where all building foundations are to be supported. Your contractor should be prepared for this eventuality. Once the building and pavement area subgrade is opened it should be proofrolled under our representatives full time observation. This procedure determines the presence and approximate areal extent of any soft or unstable areas. It can be accomplished in this case with the dead weight of a steel wheel roller, without use of vibration. Any areas that appear soft or unstable should be appropriately moisture conditioned and rernmpacted. If after recompaction they remain soft or unstable, they should be overexcavated to a depth that will provicle a stable subgrade. Typically a depth of two to three feet is adequate for this purpose. The overexcavated materials should be removed from the site and disposed. The resulting excavation should then be backfilled with crushed rock or compacted structural fill. Earth Consultants, Inc. i �