Geotech Report 04 19 2021

SOR CONSULTING ENGINEERS, INC. Garden Homes Report No. 21-C-12 Proposed Residential Development Page 10 West Orange, NJ proofrolling operations, slabs may be designed using a vertical modulus of subgrade reaction of 200 pounds per cubic inch. We recommend that slabs be underlain by a minimum 4-inch thick layer of clean %-inch size crushed stone to provide a capillary break as well as a porous drainage layer beneath the slab. We estimate that post-construction settlements of slabs designed and supported on material prepared in accordance with our recommendations would be negligible. Retaining Walls: Any below grade walls required to accommodate grade changes should include provisions for full drainage. Provided the walls are fully drained and backfilled with controlled compacted fill in accordance with previous sections of this report, the following soil parameters are recommended for wall design: Maximum Allowable Soil Bearing Pressure 4000 psf Angle of Internal Friction (@) 30 degrees Total Unit Weight of Soil 125 pef Active Earth Pressure Coefficient (Ka) 0.30 Passive Earth Pressure Coefficient (Kp) 3.25 Friction Factor — Concrete on Soil 0.40 Pavement Design Criteria: Site preparation procedures within proposed pavement areas should consist of stripping the surficial topsoil, vegetation, and all debris from within and to a distance of 5 feet beyond the pavement limits. Following general grading, but prior to placing any fill in areas to be raised, the surface should be thoroughly proofrolled and compacted to a dense and unyielding condition by numerous passes of a heavy vibratory compactor. Localized areas that cannot be compacted to a dense and unyielding condition should be removed to expose suitable subsoils and the excavations backfilled with controlled granular fill in accordance with the recommendations presented in previous sections of this report. Assuming that the pavement subgrade soils are compacted to a dense and unyielding condition immediately prior to construction, pavements may be designed using an estimated California Bearing Ratio (CBR) value of 6 percent. Based on this value, we recommend the following minimum pavement design sections for flexible pavements: