6.1.B. SR 12-18-2006 - Laserfiche WebLink

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I I I I I I I I I I I I I I I I I I I November 29, 2006 . Project 06-.507B 2007 Street Reconstruction Deerfield 3rd Addition Improvements Elk River, Minnesota bedding beneath watermain and storm sewer pipe is not as critical. Compaction should be done very carefully by hand to prevent the pipe from shifting. We recommend that the backfill be compacted with a static sheep's foot roller after the backfIll is 2 feet above the top of the pipe. Vibratory compaction should only be used on clean sands or silty sands at or below optimum moisture. We recommend that excavations slope at a 1.5:1 (horizontal: vertical) ratio from the bottom of the excavation to the surface. Stockpiled material should be kept at least 2 feet from the edge of the excavation. This is the minimum required by OSHA. We recommend all construction vehicles be kept at least 5 feet from the edge of the excavation. An escape ladder should be provided at all times while workers are in the excavation. All excavations must meet OSHA standards (29 CFR1926). Earthwork: We recommend that any unsuitable, uncompacted, or unstable soils exposed during construction be removed from beneath the proposed utility structures and street section. In addition, we recommend that any excavation below a utility structure or street section be oversized one foot for every foot of fIll placed to reach planned grade (1: lover sizing). Structural Fill: The onsite soils consisting of silty sand (SM) and silty clayey sands (SC-SM) are considered fair material for use as street sub grade material. These soils are somewhat susceptible to moisture variations and would need to be dried or mixed if they become wet prior to compaction. In addition, they will likely have moisture contents above optimum for compaction and will require drying or mixing to reach optimum moisture for compaction, even in their natural state. Page 6