J_2024 05 09_West Orange Stormwater Management Plan

PSE&G Mav 17.2011 Page 9 Following excavation of the fill materials the exposed natural subgrade soils should be observed by a qualified geotechnical engineer to confirm that all softened or disturbed soils or deleterious materials have been removed. If excavations required to remove fill extend below the design foundation levels, as expected in some areas, the excavations could be backfilled with crushed stone to the design bottom of foundation levels. When excavations for new foundations are performed adjacent to existing foundations, the new foundations should be located so that a line drawn between the lower edges of adjoining footings shall not have a slope steeper than 30 degrees with the horizontal, unless the material supporting the higher footing is braced or retained or otherwise laterally supported. Backfill around the foundations should consist of approved granular soils, on-site or imported, that are free of debris and deleterious materials, and which are at moisture contents suitable for compaction to the required densities. Any imported fill materials should consist of uncontaminated, granular soils containing less than 15 percent by weight of material passing a U.S. Standard No. 200 sieve and having a maximum particle size of four inches. NJDOT dense graded aggregate or recycled concrete could be used for this purpose. The backfill should be spread in layers on the order of twelve inches or less in loose thickness and should be uniformly compacted to at least 95 percent of its maximum dry density as determined by the ASTM D-1557 test procedure. Shallow Foundation Design Criteria: It is our recommendation that the new equipment be supported by conventional spread foundations that derive their support from the undisturbed natural soils or stone backfill placed over the undisturbed natural soils in accordance with our above recommendations. Foundations for the proposed new improvements could be designed to impose maximum allowable net bearing pressures of up to 4,000 pounds per square foot. We recommend all foundation bearing soils be observed by a qualified geotechnical engineer to confirm that