2400 33RD ST GEOTECHNICAL INVESTIGATION 2018-01-02 MF Import

SC 130 Milbor-Pita 6f cw=wc. In the heavily traveled areas, the Base Course should be increased to 8 inches with the asphalt thickness increasing to 4 inches. 1 5.7.3 Bus Areas - Concrete The recommended concrete pavement section requires 7.5 inches of running surface concrete over 12 inches of WSDOT Crushed Surfacing - Base Course (9-03.9(3)). This design is based on Portland Cement Ass6ciation Method. Please note that the base course is thickened to improve lateral drainage. It is recommended that perforated drains (french drains) be installed beneath the concrete pavement. The design should have the longest flow path be approximately 20 feet. See sketch below; \ \ \f\ \J Ji \ \ \ \•\•\•\•\•\ \•\ \ \ \ L \ \ \ \ \ \•'�•\•\•\•\•\•L•\K•\•\ \•\•\•\•\•\•\• J•f•f• J• J•J•%•f•J•J•J•JY•• f•J•%•J•J•f J•J J! l f J J J J J J J J•J•J•J J J J I J J ( Concrete Running Surfad distance Base Course Drainage Layer 3 inch perforated pipe WSDOT Gravel for Drainages 5.8 Site Drainage and Erosion Considerations 5.8.1 Surface Water Control I Surface runoff can be controlled during construction by careful grading practices. Typically, these include the construction of shallow, upgrade perimeter ditches or low earthen berms and the use of temporary sump pumps to collect runoff and prevent water from damaging exposed subgrades. In addition, measures should be taken to avoid impounding of surface water during construction. 1 Permanent control of surface water should be incorporated in the final grading design. Adequate surface gradients and drainage systems should be incorporated into the design such that surface runoff is directed away from structures and pavements and into swales or other controlled drainage devices. 1 .).8.2 Erosion Control During construction at the site, implementing the recommendations presented in the previous section or. wet weather earthwork can minimize erosion. The erosion control devices should be in place and remain in place throughout site preparation and construction. Establishing vegetation within disturbed areas immediately following grading operations may also minimize potential problems associated with erosion. Vegetation with deep penetrating roots is the preferred choice for erosion control, since the roots tend to maintain the surticial stability of slopes by mechanical effects and contribute to the drying of slopes by evapo-transpiration. Geolechnical, Tunnel and Environmental Engineers 30%0 125°i Ave NE Phone (425) 869-5778 ❑ellove, WA98005 Page 18 rue (425) 961-0677