09 ATTACHMENTS - Laserfiche WebLink

CORNERSTONE C. EARTH GROUP 5.1 UNDOCUMENTED FILLS Although undocumented fill was not encountered in our borings, we observed numerous soil stockpiles and/or loose soil spread across portions of the site. This material could possibly be reused as engineered fill provided any organic or deleterious material, such as asphalt or debris, is removed from the stockpiles. Detailed recommendations for mitigating undocumented fills are provided in the "Earthwork" section. 5.2 MOISTURE-SENSITIVE SOILS Portions of the site are blanketed by low plasticity silts and clays that are sensitive to changes in moisture content above the laboratory optimum. Silty and clayey soils will likely become soft and unstable under the weight of construction equipment during periods of heavy rain or when excessively moisture conditioned. Additional guidelines addressing this concern are presented in the "Earthwork° section. 5.3 PLANS AND SPECIFICATIONS REVIEW We recommend that we be retained to review the geotechnical aspects of the project structural, civil, and landscape plans and specifications, allowing sufficient time to provide the design team with any comments prior to issuing the plans for construction. 5.4 CONSTRUCTION OBSERVATION AND TESTING As site conditions may vary significantly between the small-diameter borings performed during this investigation, we also recommend that a Cornerstone representative be present to provide geotechnical observation and testing during earthwork and foundation construction. This will allow us to form an opinion and prepare a letter at the end of construction regarding contractor compliance with project plans and specifications, and with the recommendations in our report. We will also be allowed to evaluate any conditions differing from those encountered during our investigation, and provide supplemental recommendations as necessary. For these reasons, the recommendations in this report are contingent of Cornerstone providing observation and testing during construction. Contractors should provide at least a 48-hour notice when scheduling our field personnel. SECTION 6: EARTHWORK 6.1 SITE DEMOLITION, CLEARING AND PREPARATION 6.1.1 Site Stripping The site should be stripped of all surface vegetation, and surface and subsurface improvements within the proposed development area. A detailed discussion of removal of existing fills is provided later in this report. Surface vegetation and topsoil should be stripped to a sufficient depth to remove all material greater than 3 percent organic content by weight. Based on our site observations, surficial stripping should extend about 1 to 3 inches below existing grade. At Ponderosa Active Adult Community Page 11 132-2-1