2701 ROCKEFELLER AVE NIMBUS Geotech Report 2023-12-29

Opportunely Zone Development LLC June 6, 2019 JN 191U Page 7 economical than cantilevered walls where the depth of excavation is greater than about 15 feet. Soldier Pile Installation Soldier pile walls would be constructed after making planned cut slopes, and prior to commencing the mass excavation, by setting steel H-beams In a drilled hole and grouting the space between the beam and the soil with concrete for the entire height of the drilled hole. The contractor should be prepared to case the holes or use the slurry method if caving soil is encountered. Excessive ground loss In the drilled holes must be avoided to reduce the potential for settlement on adjacent properties. If water is present in a hole at the time the soldier pile is poured, concrete must be tremled to the bottom of the hole. As excavation proceeds downward, the space between the piles should be lagged with timber, and any voids behind the Umbers should be filled with pea gravel, or a slurry comprised of sand and fly ash. Treated lagging is usually required for permanent walls, while untreated lagging can often be utilized for temporary shoring walls. Temporary vertical cuts will be necessary between the soldier piles for the lagging placement. The prompt and careful installation of lagging is important, particularly in loose or caving soil, to maintain the integrity of the excavation and provide safer working conditions. Additionally, care must be taken by the excavator to remove no more soil between the soldier piles than is necessary to Install the lagging. Caving or overexcavation during lagging placement could result in loss of ground on neighboring properties. Timber lagging should be designed for an applied lateral pressure of 30 percent of the design wall pressure, if the pile spacing Is less than three pile diameters. For larger pile spacings, the lagging should be designed for 50 percent of the design load. Soldier Pile Wall Design Temporary soldier pile shoring that is cantilevered or restrained by one row of tiebacks, and that has a level backslops, should be designed for an active soil pressure equal to that pressure exerted by an equivalent fluid with a unit weight of 25 pounds per cubic foot (pcf). Five (5) pct should be added to this active pressure of the wall is considered permanent. If two or more tie -back anchors are used, a temporary pressure of 17H (where H is the wall height) should be used. Plate 7 attached to this report presents design considerations for soldier pile shoring that Is cantilevered or restrained by one row of tiebacks. General considerations for the design of tled-beck anchors or braced soldier -pile walls where two or more anchors or braces are used are presented on Plate S. Traffic surcharges can typically be accounted for by increasing the effective height of the shoring wall by 2 feet. The existing southern adjacent building will exert a surcharge on the proposed southern shoring wall and permanent southem foundation wall, unless the adjacent building Is underpinned — as noted In the General section, more information should be obtained to determine the surcharge pressure of this building If it is not underpinned. Soldier piles are a viable option to use as underpinning. Slopes above the shoring walls will exert additional surcharge pressures. These surcharge pressures will vary, depending on the configuration of the cut slope and shoring wall. GEOTECH CONSULTANTS, INC.