9910 EVERGREEN WAY SPRINT ANTENNA 2018-01-01 MF Import

• • • LSI Adapt Modulus of Suberade Reaction Method: Using this methoti, the pier is designed to resist lateral loads based on acceptable lateral dellection limiu. For sandy soils, the coefficient of horizontal subgrade reaction (kh) is considered to be directly proportional to the depth along the pier. The formula to detertnine kh is ki,= nhx, where x is the depth belou� the ground surface ia inches. We recommend using the value for the constant of horizontal subgrade reaction (nh) for the various soil types presented in Table 4 below. Tablc 4 Constant of Horizontal Subgradc Rcaction (nh) Depth (feet) nn (pci) 0-2 0 2-12 15 12-20 25 20-29.5 50 Construction Considerations: Our exploratiott reveale� the site soils to typically consist of soft sandy silt and loose silty sand overlying medium dense to very dense silry sand with graveis which extended to the full explored depth. Oversize materials, such as gravels and cobbles were indicated by drill action and present in cuttings from the advancement of the auger. Groundwater was encountered at the time of our exploration. The foundation-drilling contractor should be prepared to case the excavation to prevent caving and raveling of the pier shafi sidewall, if necessary due to loose soil or groundwater seepage conditions. Site soils will likely contain oversize particles and obstructions to drilling and difficult drilling conditions should be anticipated. Depending on the depth of pier penetration, wc d� anticipate that dewatering will be reyuired. Should unanticipated heavy groundwater inflow be encountered during drilling, it may he necessary to pump the accumulated groundwater prior to pier concrete placement. Altemauvely, the use ofbentonite slurry could be utilized to stabi:�ze the drilled pier excavation. The drilling contractor should be prepared to clean out the bottom of the pier excavation if loose soil is observed or suspected, with or without the presence of slurry or groundwater. As a minimum, we recommend that the drilling contractor have a cteanout bucket on site to remove loose soils and/or mud from the bottom of the pier. If groundwater is present and abundant within the pier hole, we recommend that the tounda[ion concrete be tremied from the bottom of the hole to displace the water and minimize the risk of contaminating the concrete mix. The Diilled Shafi Manual published by the Federal Highway Adminis[ration recommends that concrete be placed by tremie n�ethods if more than 3 inches of water has accumulat�d in the exca��ation. Strucrura! I'i!1 The following comments, reconunendations, and conclusions regarding structural fill are provided for desi��n and conswction purposes: Sprint PCS qugust 4, 2003 � Adapt Prajcct Na. WA03-9720 Page B /7