Geotech Report 04 19 2021

SOR CONSULTING ENGINEERS, INC. Garden Homes Report No. 21-C-12 Proposed Residential Development Page 9 West Orange, NJ foundation subgrade is soft or becomes wet, it should be over-excavated by 6 inches or more and replaced with compacted %-inch crushed stone. Layer of clean %-inch size crushed stone over the foundation subgrade soils would provide a stable working surface during foundation construction and limit the potential for soil disturbance and resulting loss of soil strength. Foundations established on the competent bearing controlled fill, natural sandy silt/clayey silt or silty gravelly sand or clean %-inch size crushed stone placed over these soils may be proportioned to impose a maximum allowable net bearing pressure of up to 4000 pounds per square foot. However, wall foundations should be at least 24 inches in width and column foundations at least 3 feet by 3 feet in plan dimensions. The bottoms of all exterior or exposed foundations should be established at least 3 feet below the adjacent exterior grades to provide protection from frost penetration. Interior foundations in permanently heated portions of the buildings may be established at convenient depths beneath the floor slab provided they reach the intended bearing stratum. Foundations deriving their support from the competent basalt bedrock may be proportioned to impose a maximum allowable net bearing pressure of up to 8 tons per square foot. Footings deriving their support directly on basalt bedrock may be established at convenient depths beneath the ground level slab. We estimate that differential settlements between foundations deriving their support from the undisturbed natural soil, compacted fill and basalt bedrock would be approximately % of 1 inch. Post-construction settlements of foundations established on bedrock would be negligible. In the event the foundation will be established partially on bedrock and partially on soil, we recommend either over-excavating the bedrock a depth of 12 inches and replacement with controlled compacted fill or providing a construction joint. Slab-On-Grade Design Criteria: We recommend that immediately prior to slab construction, the exposed subgrade soils be recompacted and proofrolled to a dense and unyielding condition by multiple passes of a vibratory steel-drum compactor. Any localized areas that cannot be recompacted to a dense and

subgrade soils be recompacted and proofrolled to a dense and unyielding condition by multiple passes of a vibratory steel-drum compactor. Any localized areas that cannot be recompacted to a dense and unyielding condition should be removed to expose suitable subsoils and the excavations backfilled with controlled compacted backfill or clean %-inch size crushed stone. Following the recompaction and in)