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<br />9 <br /> <br />Field tests (double ring infiltrometer) can be performed within the proposed infiltration basin <br />area to verify infiltration rates of the in-situ soils. We would be pleased to provide these <br />services if required or requested. <br /> <br /> <br />5.0 CONSTRUCTION CONSIDERATIONS <br /> <br />5.1 Excavation <br /> <br />Below the topsoil or aggregate base, the soils encountered in the borings consisted of sandy <br />lean clay meeting the ASTM Classification of CL. These soils will generally be Type B soils <br />under Department of Labor Occupational Safety and Health Administration (OSHA) <br />guidelines. <br /> <br />An OSHA-approved qualified person should review the soil classification in the field. <br />Excavations must comply with the requirements of OSHA 29 CFR, Part 1926, Subpart P, <br />“Excavations and Trenches.” This document states excavation safety is the responsibility of <br />the contractor. The project specifications should reference these OSHA requirements. <br /> <br />Temporary excavations in Type B soils should be constructed at a minimum of 1 foot <br />horizontal to every 1 foot vertical within excavations. Slopes constructed in this manner may <br />still exhibit surface sloughing. If site constraints do not allow the construction of slopes with <br />these dimensions, then temporary shoring may be required. <br /> <br />5.2 Observations <br /> <br />A geotechnical engineer or a qualified engineering technician should observe the excavation <br />subgrade to evaluate if the subgrade soils are similar to those encountered in the borings and <br />adequate to support the proposed construction. <br /> <br />5.3 Backfill and Fills <br /> <br />We recommend moisture conditioning all soils that will be used as fill or backfill in accordance <br />with Section 4.3 above. We recommend that fill and backfill be placed in lifts not exceeding 4 <br />to 12 inches, depending on the size of the compactor and materials used. <br /> <br />5.4 Testing <br /> <br />We recommend density tests of backfill and fills placed for roadway and/or house <br />foundations. Samples of the proposed materials should be submitted to our laboratory prior <br />to placement for evaluation of their suitability and to determine their optimum moisture <br />content and maximum dry density (Standard Proctor). <br /> <br />5.5 Winter Construction <br /> <br />If site grading and construction is anticipated to proceed during cold weather, all snow and <br />ice should be removed from cut and fill areas prior to additional grading and placement of <br />fill. No fill should be placed on frozen soil and no frozen soil should be used as fill or backfill. <br /> <br />215