Report/excavation observation/compaction testing

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- AET Job No. 20-06374 - Page 4 of 6 soils exposed in the excavation, we conducted shallow hand auger borings and hand cone penetrometer probes in the bottom of the excavation. The soils encountered were classified in general accordance with ASTM:D2488. Estimates were made of their strength properties based on their resistance to advancement of the hand auger and from the hand cone penetrometer readings. The soils were also compared to those described by the preliminary boring logs. The soils exposed in the base of the excavation were judged to be naturally deposited lean clays and sandy lean clays, similar to those described in the preliminary report and the associated soil boring logs. Hand cone penetrometer readings indicated these natural soils should be capable of supporting unit stresses of at least 2,500 psf. The observed soils were judged suitable for support of the fill and building loads. The attached Excavation Observations Sketch (Figure 1) illustrates the extent of the excavation we observed and the approximate elevations of the excavation bottom. In portions of excavation, existing fill soils and soft clays were observed in the area of an existing and abandoned septic system. These soils were judged unsuitable for support of the footi.ng, floor slab and fill loads. We recommended that these soils be removed to expose the underlying naturally deposited sandy lean clays. These naturally deposited sandy lean clays were judged suitable to support the fill and structural loads. We visited the site during subsequent trips to observe that the fill and soft clays in the excavation had been removed. The soils exposed in this excavation were judged to be naturally deposited sandy lean clays. These natural clays were judged suita.ble to support the fill and structural loads. The approximate area of this excavation is also identified on the attached sketch. Standing water was observed in parts of the excavation due to perched water from the abandoned septic system and a drainage system from the existing parking lot area. A majority of water was removed from the bottom of the mass excavation, leaving small amounts (up to 2") of water in localized areas. Since the fill being used consisted of relatively free-draining sand, it was our opinior.that this sma.11 amou.nt of standing water should not inhibit compaction efforts.