Laserfiche WebLink
I <br /> amec <br /> Ifoster <br /> wheeler <br /> Table 4 Measured Depth to Permeable Soil Layers <br /> Exploration Depth to permeable layer(feet) <br /> I B-01 17.0 <br /> B-02 15.0 <br /> B-03 10.0 <br /> I B-04 15.0** <br /> B-05 15.5 <br /> ** Estimated Depth based on Driller Refusal <br /> I <br /> Estimated infiltration rate: We developed preliminaryestimates of infiltration usingthe following two <br /> p 9 <br /> Iapproaches from the Everett Stormwater Manual: <br /> ► Method 1. USDA Soil Textural Classification as outlined on Figure 9.1, Table 9.1; and <br /> I ► Method 2. ASTM Gradation Testing at Full Scale Infiltration Facilities using grain size <br /> distribution from ASTM D422, and D10 size, as presented in Table 9.2. <br /> IMethod 1: Preliminary Infiltration Rates Based on USDA Textural Classification <br /> Sample Number/ Infiltration Rate <br /> Exploration Depth (feet) %sand' USDA Soil Type (inches/hour) <br /> IB-01 S-6, 20 to 21.5 90 Sand 2 <br /> B-02 S-5, 17.5 to 19 82 Loamy Sand 0.5 <br /> B-03 S-4, 12.5 to 15 75 Sandy Loam 0.25 <br /> I B-05 S-5, 17.5 to 19 87 Loamy Sand 0.5 <br /> 1. Calculated neglecting gravel fraction. <br /> IMethod 2: Preliminary Infiltration Rates Based on Gradation Testing <br /> Sample <br /> I Number/Depth Dio Infiltration Rate <br /> Exploration (feet) Soil Type (mm) (inches/hour) <br /> B-01 S-6, 20 to 21.5 Sand, some silt 0.7 9 <br /> I <br /> B-02 S-5, 17.5 to 19 Silty sand 0.2 3.5 <br /> B-03 S-4, 12.5 to 15 Silty sand with some gravel 0.2 3.5 <br /> B-05 S-5, 17.5 to 19 Silty sand 0.2 3.5 <br /> I <br /> Recommended Infiltration Rate for Preliminary Design: We would recommend using an infiltration rate <br /> Iof 1.5 inch per hour for preliminary design. Additional in situ testing, such as pilot infiltration tests <br /> (PIT), will be needed to estimate the infiltration rates for final long-term design. Tests should be <br /> I conducted at the actual planned location of the infiltration facilities and at the planned infiltration <br /> elevation. Multiple tests should be performed to verify design assumptions. <br /> IAmec Foster Wheeler <br /> Project No.6-917-18116-0 17 <br /> II \\Sea-fs1\WordProc\ Projects\18000s\18116 Everett School District\Geotech Report\Revised\2017_10-19_Everett Middle School Geotech_Sx.docx <br />