1802 75TH ST SW Geotech Report 2022-10-25

-4- Penetration Resistance. This resistance, or blow count, provides a qualita- tive measure of ,the relative density of granular soils and consistency of cohesive soils. Representative portions of the split -spoon samples were placed in jars, sealed and transported to our laboratory for further observa- tion. In addition, soil samples were taken from the auger cuttings for a representative sample for the sieve analysis. An engineer from our firm was present throughout the field work program to i observe the exploration, assist in sampling, and to prepare the descriptive i log of the exploration. Soils were classified in general accordance with ASTM 0-2488, "Standard Practice for Description and Identification of Soils (Visual -Manual Procedure)". The final exploration log represents our interpretation of the contents of the field log. Geotechnical laboratory testing consisted of six moisture content determi- nations, and one gradation test to aid in classification of the soils and to assist in evaluating engineering characteristics. Results of the moisture content determinations are listed on the boring logs, Figures 2 and 3, grada-. tion results are graphically presented on Figure 4, and the moisture -density relations according to ASTM D-1557 are presented on Figure 5. Resistivity testing was performed on a combined sample from borings B-1 and B-2 from 5 to 10 feet below the ground surface according to ASTM G-57. This test showed a soil resistivity of 120 ohm -meters at a field moisture content j of 9.3 percent. The soil is relatively impermeable so we do not expect that ll this value will fluctuate throughout the year. SITE CONDITIONS The existing substation site is located on a level area which appears to have been cut out of a small rise. The station subgrade is covered with crushed gravel smaller than about 2 inches in size. f Our explorations indicate that the site is underlain by unweathered glacial till. Glacial till is an unsorted mixture of sand, silt, clay, and gravel which was deposited in front of or beneath advancing continental glaciers Converse Consultants NW