2530 MADISON ST 2016-01-01 MF Import

AirTouch Cellular 7-81 M-11905•C 3 October 1997 Pa9e 4 I ,�4 eismic Conditions According to the Sersmic Zone Map of ihe United States contained in the 1994 Uniform � Buildiny Code, the projec: site lies within seismic risk zone 3. Based on soil co�iditions encountered at the sita, we interpret the subsurface site conditions to correspond to a seismic soil profiie type S-2, as defined by Table 7 6-J of the 1994 Uni/o�m Building Code. � Soil Profile type S-2 applies to a profila consisting of predomina�tly medium-dense to dense or medium-stiff to stiff soil which exceeds 200 feet in depth. '_ 4.0 CONCLUSIONS AND RECOMMENDATIONS The proposed ccnstruction is feasible from a geotechnical perspective, giv�n the subsurface conditions disclosed in our fie!d exploration. Our specific recominendations concerring site preparation, tower and equipment shelter foundations, and structural fill placement are presented in the following sections, along wich preliminary cunclusions rPgarding environmental conditions. 4.1 $ite Preuaration Site preparation will involve temporary drainage, cic �ring and grubbing, preparing subgrades and other construction activities. The following comments and recommend�tions a�ply to site preparation. i Temoorarv Draina e: We recommend that initial site preparation involve intercepting and diverting any potential sources of surface or near-surface wuter within the construction I zones. Because the selection of an appropriate drainage system will depend on the water � quantity, season, weather cenditions, construction sequence, and contractor's methods, 1 final decisions regarding drainage systems are best made in the field at the time of constructicn. Nonetheless, we anticipate that berms or ditches placed along the uphill side of the work areas will adequately intercept surface water runoff. � Clearina and Grubbina: Once surface ru�off is controlled, site preparation should include clearing, grubbing, and removal of all vegetation, sod, topsoil, any organic-ricn soils from f foundation and fill areas. Based on the observed soil conditions, we estimate the stripping � depths needed to remove vegetation and topsoil to range from approximately 1 to 3 inches, with localized deeper stripping required for removal of root balls. Sub4rade Protectio+i: Because of the relatively high silt content of the near-surface site soils, these soils are moisture-sensitiue and prone to disturbance when wet. 7o reduce site disturbance, the contractor shoulcl minimize traffic abeve prepared subgrades. During wet conditions, the use of a working :;urface oi quarry sp�lls or clean sand and gravel may be required to protect tha subgrade, especially from vehicular traffic. )•YIM•71006-0