SHI Builders West Orange NJ Prelim GI SWM Report 1

5.6 Preliminary Groundwater Considerations Indicators of seasonal high groundwater were encountered during this investigation as shallow as 1.4 feet below existing site grades. As such, groundwater control measures should be anticipated for this project, as detailed below. Permanent Groundwater Control: The need for permanent groundwater control measures should be evaluated along with the final site grading plans by the project’s structural engineer and architect as part of the building design. Waterproofing and permanent groundwater control measures are recommended along proposed foundation walls that will be located below the seasonal high groundwater level. In addition, under slab drains and sump pumps are recommended where the finished floor slab is near the groundwater elevation. Alternatively, the project’s structural engineer can include considerations for resisting the buoyant pressure (such as increasing the thickness of the floor slab) for the design of the floor slab. Temporary Groundwater Control: The contractor should anticipate the need for groundwater control within proposed excavations. Typically, excavations extending less than approximately two feet below the groundwater levels may be controlled by providing a sufficient number of sump pumps to draw down groundwater below the bottom of excavations. Deeper excavations that remain open for extended periods will require more extensive dewatering, possibly including installation of deep well points. The contractor should be responsible for providing adequate groundwater control so that proper installation of below grade structures can be accomplished. While the means of groundwater control will need to be determined by the contractor, the use of gravity fed sump pumps are typically suitable for dewatering of surface runoff, perched and infiltrating water. Surface water runoff must be controlled and diverted away from construction areas by grading and limiting the exposure of excavations to rainfall. 5.7 Preliminary Retaining Walls and Lateral Earth Pressure Recommendations Proposed retaining wall structures were not identified at this time; however, retaining wall structures may be proposed due to existing site topography and/or along the property lines (if necessary). Dynamic Earth presents the following preliminary design recommendations for use when designing proposed

may be proposed due to existing site topography and/or along the property lines (if necessary). Dynamic Earth presents the following preliminary design recommendations for use when designing proposed retaining walls requiring lateral earth pressure estimates. Soil Parameters and Design Considerations: Proposed retaining walls that are free to rotate generally can be designed to resist active earth pressures. Restrained walls and retaining wall corners need to be designed to resist at-rest earth pressures. Backfill soils adjacent to these structures should consist of freely draining materials composed primarily of sand and gravel. The SHI Builders 14 4266-99-001E