5828 GLENWOOD AVE CINGULAR WIRELESS ANTENNA Geotech Report 2022-10-25 (2)

Adapt Engineering exploration indicated that an average thickness of about 12 inches of sandy topsoil with silt and gravel mantling very loose, poorly graded sand may be encountered across the tower lease area, but significant variations could exist. It should be realized that if the stripping operation proceeds during wet weather, a generally greater stripping depth might be necessary to remove disturbed, surficial, moisture-sensitive soils; therefore, stripping is best performed during a period of dry weather. Backfill materials, where required, should be placed and compacted according to the recommendations presented in the Structural Fill section of this report. Excavations: Site excavations ranging up to 2 feet deep are anticipated to accommodate the proposed equipment pad footings. Based on our exploration,we anticipate that these excavations will encounter 12 inches of sandy topsoil with silt and gravel mantling very loose, poorly graded sand. We anticipate these surficial soils can be cut with conventional earth working equipment such as small dozers and trackhoes. Backfill materials, where required, should be placed and compacted according to recommendations presented in the Structural Fill section of this report. Temporary Cut Slopes: All temporary soil cuts (greater than 4 feet in height) associated with site excavations or regrading activities should be adequately sloped back to prevent sloughing and collapse, unless a shoring box or other suitable excavation side wall bracing is provided. We tentatively recommend a maximum cut slope inclination of 1.5H:1V (Horizontal:Vertical) within the surficial soils that will likely be exposed within the upper 2 feet below the ground surface across the site. If groundwater seepage is encountered within the excavation slopes,the cut slope inclination may need to be on the order of 2H:1 V, or flatter. However, appropriate inclinations will ultimately depend on the actual soil, rock and groundwater seepage conditions exposed in the cuts at the time of construction. It is the responsibility of the contractor to ensure that the excavation is properly sloped or braced for worker safety protection,in accordance with OSHA safety guidelines. In addition to proper sloping,the excavation cuts should be draped with plastic sheeting for the duration of the excavation to minimize surface erosion and ravelling. Dewatering: Based on our site reconnaissance investigation,we do not anticipate significant groundwater seepage within the upper 2 feet. However, shallow perched groundwater was encountered in the test boring and may be encountered during construction depending on the actual excavation depth and the time of year that construction proceeds. If groundwater is encountered, we anticipate that an internal system of ditches,sump holes,and pumps will be adequate to temporarily dewater the excavations. Subgrade Preparation: Exposed subgrades for shallow footings, slabs-on-grade, roadway sections and other structures should be compacted to a firm, unyielding state, if required to achieve adequate density and warranted by soil moisture conditions. Any localized zones of loose, granular soils observed within a subgrade area should be compacted to a density commensurate with the surrounding soils.In contrast,any uncontrolled fill material or organic, soft, or pumping soils observed within a subgrade should be overexcavated and replaced with a suitable structural fill material. AT&T Mobility do General Dynamics October 10,2016 Adapt Project No.WA16-20654-GEO