Agenda - Council - 09/14/2021 - Laserfiche WebLink

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included with this report represents an interpretation of the field logs and include modifications based on visual/manual method observation of the samples. The soil boring logs, general terminology for soil description and identification, and classification of soils for engineering purposes are also included in the appendix. The soil boring log identify and describe the materials encountered, the relative density or consistency based on the Standard Penetration resistance (N-value, "blows per foot") and groundwater observations. The strata changes were inferred from the changes in the samples and auger cuttings. The depths shown as changes between strata are only approximate. The changes are likely transitions, variations can occur beyond the location of the boring. Three piezometers were also installed during drilling operations. One piezometer was installed in the borehole of soil boring SB-4, SB-6 and SB-10. The piezometer consists of a 10 foot long, 1 inch diameter schedule 40 slotted well screen and riser pipe set at about 20 feet below the ground surface. A sand pack was placed around the well screen and bentonite seal placed above the sand pack. A lockable steel protector pipe was then placed over the riser pipe and grouted in -place. 3.0 RESULTS 3.1 Soil Conditions At the surface, the soil borings encountered about 1 foot of topsoil consisting of poorly graded sand with silt and silty sand that was dark brown or brown in color and contained traces of roots. Below the topsoil, the soil borings encountered alluvial soils that extended to the termination depths of the borings. The alluvial soils predominantly consisted of poorly graded sand, poorly graded sand with silt with minor amount of silty sand encountered in soil boring SB- 6. Clayey sand and silty clay were encountered below the topsoil at soil boring SB-10 and extended to depth of about 12 feet below the ground surface. Silty clay and clayey sand were also encountered in soil boring SB-12 at about 12 feet below the ground surface and extended to the termination depth of the boring. Penetration resistance values (N-Values), shown as blows per foot (bpf) on the boring logs, within the poorly graded sand, poorly graded sand with silt and silty sand ranged from 2 to 21 with most of the values less than 10 bpf. These values indicate the soils had a very loose to medium dense relative density but were mostly very loose to loose. N-Values within the clayey sand and silty clay ranged from 2 to 10 bpf indicating soft to rather stiff consistency. 3