Agenda - Council - 05/14/2024 - Laserfiche WebLink

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August 8,2023 Itt Project 23-193 City Project#24-01 Fox Ridge Estates Ramsey,Minnesota Utility Installation: We recommend that all utility pipes lay in non-organic mineral soils capable of supporting the pipes. Excessive over-excavation beneath the pipes should be avoided. We recommend that 2 to 6 inches of granular bedding material be placed and compacted around the pipe to aid in aligning the pipe for line and grade. The natural sand (SP) soils appear suitable for this purpose. The silt (ML) and clay(CL,CL-ML, CH) are not. Compaction should be done very carefully by hand to prevent the pipe from shifting. We recommend that the backfill be compacted with a vibratory 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). Trench Backfill: The on-site soils consisting of poorly graded sands (SM, SP) are considered excellent for use as utility trench backfill. These soils are generally easy to work with and compact with vibratory compaction equipment. The on-site soils consisting of silt (ML), silty clays (CL-ML) and highly plastic clay (CH) are considered very poor material for backfill. These soils will be wet and will require drying or mixing to reach optimum moisture for compaction. In addition, they are highly susceptible to seasonal moisture variations and frost heave. The silts (ML), silty clays (CL-ML) and highly plastic clay (CH) should not be used as utility trench backfill within 4 feet of finished subgrade. No organic soils, roots, stumps, logs, brush, etc. should be used as structural fill below any Page 7