Agenda - Public Works Committee - 04/16/2024

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5.0 CONSTRUCTION CONSIDERATIONS 5.1 Excavation The soil encountered in the borings consisted of a variety of both sandy and clayey soil types. The sandy soils included; poorly graded sand, poorly graded sand with silt, silty sand, clayey sand and silty clayey sand corresponding to the ASTM classifications SP, SP-SM, SM, SC and SC-SM, respectively, and will be Type C soils under Department of Labor Occupational Safety and Health Administration (OSHA) guidelines. The clayey soils included; lean to fat clay, lean clay, sandy lean clay, lean clay and silty clay correspond to the ASTM Classifications CL-CH and CL. These soils will generally be Type B soils under Department of Labor Occupational Safety and Health Administration (OSHA) guidelines. Temporary excavations in Type C soils should be constructed at a minimum of 1 1/2foot horizontal to every 1 foot vertical within excavations. Temporary excavations in Type C soils should be constructed at a minimum of 1 foot horizontal to every 1 foot vertical within excavations. Slopes constructed in this manner may still exhibit surface sloughing. If site constraints do not allow the construction of slopes with these dimensions, then temporary shoring may be required. 5.2 Observations A geotechnical engineer or qualified engineering technician should observe the excavation subgrade to evaluate if the subgrade soils are similar to those encountered in the borings and adequate to support the proposed construction. 5.3 Backfill and Fills Site soils that will be excavated and reused as backfill and fill appear to be below their assumed optimum moisture content. We anticipate it may be necessary to moisture condition (wet) these soils to achieve the recommended compaction. We recommend that fill and backfill be placed in lifts not exceeding 4 to 12 inches, depending on the size of the compactor and materials used. 5.4 Testing We recommend density tests of backfill and fills placed for the proposed roadway and utilities. Samples of the proposed materials should be submitted to our laboratory prior to placement for evaluation of their suitability and to determine their optimum moisture content and maximum dry density (Standard Proctor). 5.5 Winter Construction If site grading and construction is anticipated to proceed during cold weather, all snow and ice should be removed from cut and fill areas prior to additional grading and placement of fill. No fill should be placed on frozen soil and no frozen soil should be used as fill or backfill. Concrete delivered to the site should meet the temperature requirements of ASTM and/or ACI. Concrete should not be placed on frozen soil. Concrete should be protected from freezing until the necessary strength is obtained. 13