3400 RIVERFRONT BLVD Geotech Report 2022-10-25

• • • • U.S. Standard No. 4 Sieve. The material should be free of organic matter and other deleterious • material and should be placed in one lift and compacted until well keyed. While we have described certain approaches to the trench excavation, it is the contractor's • responsibility to select the excavation and dewatering methods, monitor the trench excavations for safety, and provide any shoring required to protect personnel and adjacent improvements. • All trench excavations should be in accordance with applicable OSHA and state regulations. • 6.5.3 Trench Backfill Material • Trench backfill for the utility pipe base and pipe zone should consist of durable,well-graded • granular material containing no organic or other deleterious material, have a maximum particle • size of 3 inch, and have less than 8 percent by dry weight passing the U.S. Standard No. 200 Sieve. • Backfill for the pipe base and within the pipe zone should be placed in maximum 12-inch-thick • lifts and compacted to not less than 90 percent of the maximum dry density, as determined by ASTM D 1557, or as recommended by the pipe manufacturer. Backfill above the pipe zone • should be placed in maximum 12-inch-thick lifts and compacted to not less than 92 percent of the maximum dry density, as determined by ASTM D 1557. Trench backfill located within 2 feet • of finish subgrade elevation should be placed in maximum 12-inch-thick lifts and compacted to • not less than 95 percent of the maximum dry density, as determined by ASTM D 1557. . 6.6 TEMPORARY SLOPES • Excavation side slopes less than 10 feet high should be no steeper than 1 Y2H:1 V, provided groundwater seepage does not occur. If slopes greater than 10 feet high are required, • GeoDesign should be contacted to make additional recommendations. We recommend a minimum horizontal distance of 5 feet from the edge of the existing improvements to the top of • the temporary slope. All cut slopes should be protected from erosion by covering them during wet weather. If sloughing or instability is observed, the slope should be flattened or supported • by shoring. Excavations should not undermine adjacent utilities, foundations, walkways, streets, • or other hardscapes unless special shoring or underpinned support is provided. 6.7 PERMANENT SLOPES Permanent cut or fill slopes should not exceed a gradient of 2H:1V, unless specifically evaluated • for stability. Upslope buildings, access roads, and pavements should be set back a minimum of • 5 feet from the crest of such slopes. Alternatively, the setback at the top of the slopes can be determined on a case-by-case basis by the geotechnical engineer. Slopes should be planted with appropriate vegetation to provide protection against erosion as soon as possible after grading. • Surface water runoff should be collected and directed away from slopes to prevent water from • running down the face of the slope. • 6.8 EROSION CONTROL • The on-site soil is moderately susceptible to erosion. Consequently, we recommend that slopes • be covered with an appropriate erosion control product if construction occurs during periods of • wet weather. We recommend that all slope surfaces be planted as soon as practical to minimize erosion. Surface water runoff should be collected and directed away from slopes to prevent • • • G EODESIGN? 16 Polygon-128-01:091615 •