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625 Cypress Avenue Geotechnical Investigation Project No. W1895-88-01 - 31 - April 23, 2024 (December 2013). Additional correction factors may be required and should be applied by the engineer in responsible charge of the design of the stormwater infiltration system and based on applicable guidelines. Percolation test results are provided on Figures 19 and 20. Boring Soil Type Infiltration Depth (ft) Average Infiltration Rate (in / hour) B2 Sandy Silt (ML) 15 – 25 0.02 B3 Sandy Clay (CL) 2.5 – 5 3.78 7.12.3 The results of the percolation testing indicate that the soils at B3 are conducive to infiltration. It is our opinion that the soil zones encountered at the depths and location of boring B3 as listed in the table above are suitable for infiltration of stormwater. 7.12.4 It is our opinion that the introduction of stormwater at the depth and location indicated above will not induce excessive hydro-consolidation (see Figures B7 through B15), will not create a perched groundwater condition, will not affect soil structure interaction of existing or proposed foundations due to expansive soils, will not saturate soils supported by existing or proposed retaining walls, and will not increase the potential for liquefaction. Resulting settlements are anticipated to be less than ¼ inch, if any. 7.12.5 Where infiltration systems will be utilized, it is recommended that a minimum 10-foot horizontal and vertical setback be maintained from existing or proposed foundations. Additional setbacks may be required by the governing jurisdiction and should be incorporated into the stormwater infiltration system design as necessary. 7.12.6 Subsequent to the placement of the infiltration system, it is acceptable to backfill the resulting void space between the excavation sidewalls and the infiltration system with minimum two-sack slurry provided the slurry is not placed in the infiltration zone. It is recommended that pea gravel be utilized adjacent to the infiltration zone so communication of water to the soil is not hindered. 7.12.7 Due to the preliminary nature of the project at this time, the type of stormwater infiltration system and location of the stormwater infiltration systems has not yet been determined. The design drawings should be reviewed and approved by the Geotechnical Engineer. The installation of the stormwater infiltration system should be observed and approved by the Geotechnical Engineer (a representative of Geocon).