Stormwater Management Report 4898 2292 85031

Client: Gomes Management Project: 525 Northfield Avenue, West Orange, NJ Page: 8 Date: 09/03/2024 FLOOR SLAB DESIGN CRITERIA: Removal of fill from top 2’-6” in boring B-1, from top 4’ in B-2/2A, from top 4’-11” in B- 3, from top 5” in B-4, from top 2’ in B-5/5A and from top 9” in B-8 will be required. The floor slab or patio slab shall be supported directly on the compacted sub-grade of onsite material or controlled compacted structural fill. Compaction of the sand below the floor slab sub-grade to 95% of its optimum density will be required. We recommend performing compaction test at the rate of one test per 200-sq.ft area. Recommended Modulus of Sub-Grade reaction is 75 pci. Any back fill required for the structural area to be off site or %” clean crushed stones may be utilized to minimize the influence of moisture on the first fill layer. All off-site fill should composed of relatively well graded sand and gravel containing less than 15% by weight passing U.S. Standard #200 sieve and having a maximum particle size of six inches. Acceptable soil materials for backfill and fill should be free of clay, rock or gravel larger than six (6) inches in any dimension, debris, waste, frozen materials, vegetable and other deleterious matter and it should comply with ASTM D-2487-91 soil classification groups GW, GP, SM, SW and SP. All fill should be placed in lifts in the order of twelve (12) inches in loose thickness and it should be uniformly compacted to at least 95% of its maximum dry density as determined by the modified proctor density values derived based upon ASTM D-1557-93 test procedure. In addition, we recommend that backfill soils placed in confined areas, such as foundation or utility excavations, should be spread in lifts in the order of six to eight inches in loose thickness and be compacted to the same degree using manually operated vibratory compaction equipment. BELOW GRADE WALLS: We recommend that the exterior building walls should be constructed with a continuous perimeter foundation drain to convey localized groundwater seepage away from the building and prevent the hydrostatic pressures built-up against the walls. The drain could consist of a 6 to 8 inch diameter PVC pipe surrounded on all sides by a minimum of six (6) inches of clean 3/8” crushed gravel. The pipe should drain by gravity to the site storm water system, if feasible, or

of a 6 to 8 inch diameter PVC pipe surrounded on all sides by a minimum of six (6) inches of clean 3/8” crushed gravel. The pipe should drain by gravity to the site storm water system, if feasible, or should be connected to a sump pit where any water could be removed by pumping. Soil Unit weight (total): 120 pef Angle of Internal Friction: 31 degrees Coefficient of sliding friction: 0.4 Coefficient of active earth pressure: 0.28 Coefficient of passive earth pressure: 3.57 RECOMMENDATIONS FOR THE EARTHWORK FOUNDATION CONSTRUCTION: Clearing and Stripping: Clearing and stripping would include removing vegetation and any boulders or any loose or unsuitable soil at the distance of 5 feet beyond the limits of the proposed building excavation, structure and paved areas. Limits of stripping should conform to construction permit limitations. Soil Erosion and Sediment Control: Clearing and stripping should be performed in accordance with the requirements of the soil erosion and sediment control plan and environment permits.