2207 GIBSON PL 2022-10-28 - Laserfiche WebLink

August 18,2014 Gibson Bluff L&A Job No. 14-056 Page 20 LIST OF SOIL SAMPLES Sample Test Depth Soil • No. Boring No. feet Description 1 B-1 5,0-6.5 Dark olive-brown,poorly-graded SAND with silt and gravel 2 B-2 10.0- 11,5 Dark olive-brown, well-graded SAND with silt and gravel 3 B-3 10.0- 11.5 Dark olive-brown,poorly-graded SAND with silt The percentages of clay, silt, and sand/gravel of the soil samples determined from the particle size distribution tests are summarized on Plate A-2. Based on these percentages the soil samples were classified according to the USDA (U.S. Department of Agriculture) Texture Triangle chart, a copy of which is shown on Plate A-3 in the attached Appendix. The classifications of soil samples are presented in the table below. • USDA TEXTURE TRIANGLE CLASSIFICATION OF SOIL SAMPLES Sample Percentage Percentage Percentage USDA Texture No, Clay Silt Sand/Gravel Triangle Classification 1 2.0 3.4 94.6 Sand 2 2,1 5,2 92.7 Sand 3 1.8 - 4.5 93.7 Sand Volume III, Section 3.3.6,Article 3 - Soil Grain Size Analysis Method, of the Stormwater Management Manual for Western Washington, 2012 Edition, published by Washington State Department of Ecology, is used to determine estimated design infiltration rates of the target soil deposits. This method uses Do D60, D90, and fsn„ in calculating the saturated infiltration rate (conductivity), Ksat in cm/sec; where Dio ,D60,,D00 are the sizes • LITJ & ASSOCIATES, INC.