6.1.A. 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 13, 2006 Project 06-507A 2007 Street Reconstruction Irving Avenue Area Improvements Elk River, Minnesota 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 poorly graded sand (SP) and poorly graded sands with silt (SP-SM) are considered excellent material for use as street subgrade m~terial. These soil types are relatively easy to compact using vibratory compaction methods. The onsite soils ~<?~~isti~gof.silty san.~.s .cSMtar~.co.n~id~~~<iXair.!!l~le.ri~ fq~ .!lJ~ ?S _~~~~AI tHL 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 have moisture contents above optimum for compaction and will require drying or mixing to reach optimum moisture for compaction, even in their natural state. We recommend that any imported fill and utility trench backfill material consist of mineral soils meeting the requirements specified below. No organic soils, roots, stumps, t<?g~~ .l?D:!sh, ~!~~._shC)~l(t12~ .1!~~4_ as_ str:1!~1:uJal fill_below any utility structure or pavem~nt section. We recommend that all fill and utility trench backfill material be free of soft, wet or frozen soils, highly expansive soils, rubble, debris and rocks in excess of 6 inches in diameter. The fill and utility trench backfill material should be as uniform as possible both in composition and moisture content. We recommend that all fill and utility trench backfill material be placed in 12-inch loose lifts and compacted to a minimum of 95% of standard proctor maximum density (ASTM Page 6