1601 FLORIDA DR Geotech Report 2022-10-25

September 10,2017 Infiltration Tests L&A Job No. 17-095 Page 3 The deposits of the Vashon till soil unit were plowed directly under glacial ice during the most recent glacial period as the glacier advanced over an eroded, irregular surface of older formations and sediments. This soil unit is composed of a mixture of unsorted clay, silt, sand, gravel, and scattered cobbles and boulders. The Vashon till soil over the top two to four feet is normally weathered to a medium-dense state, and is moderately permeable and. compressible. The underlying fresh till soil, commonly referred to as "hard pan", is very-dense and weakly-cemented. The fresh till soil possesses a compressive strength comparable to that of low-grade concrete and can remain stable on steep natural slopes or man-make cuts for a long period. The fresh till deposits can provide excellent foundation support with little or no settlement, but are of extremely low permeability and would hardly allow stormwater to seep through. Soil Condition Subsurface conditions of the proposed access road were explored with three backhoe test pits excavated on August 23, 2017. The approximate locations of the test pits are shown on Plate 2 - Site and Exploration Location Plan. The test pits were located with either a tape measure or by visual reference to existing topographic features in the field and on the topographic survey map, and their locations should be considered as only accurate to the measuring method used. A geotechnical engineer from our office was present during subsurface exploration to monitor test pit excavation, examine soil and geologic conditions encountered, and complete logs of the test pits. Soil samples obtained from each soil layer in the test pits were visually classified in general accordance with United Soil Classification System, a LIU & ASSOCIATES, INC.