Stormwater Management Report 03302026

Client: Gomes Management Project: 525 Northfield Avenue, West Orange, NJ Page: 7 Date: 09/03/2024 Description Parameter Recommended Value Mapped Spectral Acceleration for short periods: Ss 0.282 Mapped Spectral Acceleration for 1-sec period: S, 0.059 Site Class: C Very dense Soil &Soft Rock Site Coefficient: Fa 1.3 Site Coefficient: Fv 1.5 5 percent damped Design spectral response Sos 0.245 acceleration at short periods: 5 percent damped Design spectral response So, 0.059 acceleration at 1-sec periods: 5. Any fill used as backfill material within the building and pavement areas should consist of approved portions of the on-site granular soils, which have been maintained at moisture contents suitable for compaction or select fill should be imported. All fill should be placed in lift in the order of twelve (12) inches in loose thickness and 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-1557-98 test procedure. In addition, we recommend that backfill soil placed in confined areas, such as foundation or utility excavations, should be spread in lifts in the order of six (6) to eight (8) inches in loose thickens and it should be compacted to the same degree using manually operated vibratory compaction equipment. We recommend that temporary construction slopes be established atone vertical to two horizontal, or flatter, or as required by the governing safety codes. FOUNDATION DESIGN CRITERIA: As per the r2-coastal-fema.hub.arcgis.com website and FIRM-(flood insurance rate map), the Effective Flood Zone of the subject property is AE. The properties in these flood zones

As per the r2-coastal-fema.hub.arcgis.com website and FIRM-(flood insurance rate map), the Effective Flood Zone of the subject property is AE. The properties in these flood zones have a 1%chance of flooding each year. Fill was noted in top 2'-6" in boring B-1, in top 4' in B-2/2A, in top 4'-11" in B-3, in top 5" in B-4, in top 2' in B-5/5A and in top 9" in B-8. We recommend that the foundation for the proposed 1-story retail building shall be supported by conventional shallow foundations established on the medium dense soil noted at 4' to 6' depth below grade. Foundation should be designed to impose maximum allowable net bearing pressure of 2,000 pounds per square foot. Excavation down to 10 feet depth will be required in borings B-6, B-7 & B-8 to get net bearing pressure of 4,000 psf. A complete removal of fill is recommended. Any pockets of localized unsuitable soil encountered during foundation excavation should be completely removed. The over excavated area should be backfilled utilizing either controlled compacted fill or 3/4" size clean gravels. Any footing or slab placed in this area will require over excavation, removal of unsuitable material and backfilling with 3/ 4 size stones or controlled compacted fill. Placing additional reinforcing steel to strength the footing over soft soil may be required. We recommend that exterior foundations be established at least three feet six inches below the adjacent exterior grade, or as required by local ordinance, to provide protection from frost penetration. The maximum post-construction settlements of foundations designed and constructed in accordance with our recommendations will be in the order of 3/ " or less.