4.7. SR 08-19-2019 - Laserfiche WebLink

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B. Frozen material shall be considered unsuitable material unless otherwise authorized in writing by the Engineer. C. Excavated material unsuitable for embankment and backfill construction shall become the property of the Contractor and shall be removed from the site and disposed of at a site secured by the Contractor. D. Stabilizing aggregates for use in backfilling subgrade excavations shall conform to the gradation requirements of MnDOT 3601,Granular Filter,or other coarse aggregate found to be in general compliance by the Engineer. PART 3-- EXECUTION 3.1 CONSTRUCTION REQUIREMENTS A. At the end of each day the Contractor shall eliminate surface indentations, including those caused by sheeps foot rollers,tractor tires and tracked equipment,and roll the surface with a steel wheel or rubber tired roller except in those areas designated to be protected from compaction. B. Subgrade excavation shall be performed,as directed by the Engineer,for the removal of any unstable soils that may be encountered. Such excavation shall be backfilled with suitable excess common excavation material or stabilizing aggregate as directed by the Engineer. If the Contractor proceeds without approval from the Engineer or Owner,all work and material to restore the roadbed to the proper grade shall be at the Contractor's expense. C. Once the subgrade has been successfully test rolled, no traffic or construction equipment shall be permitted to operate directly on the subgrade without the prior approval of the Engineer. The subgrade shall be relatively smooth prior to the placement of aggregate base. All equipment shall be restricted to operating only in areas where the aggregate base has been installed to its full design depth. D. Material suitable for curb backfill shall be segregated and stockpiled at a site selected by the Contractor. Following curb construction,the material shall be placed behind the curb to the subgrade level of the topsoil. E. The Contractor shall salvage and stockpile all topsoil removed during the course of the construction. This topsoil shall be used where required for turf establishment as directed by the Engineer. F. Sufficient excavated material shall be utilized by the Contractor to replace loss volume due to soil shrinkage from trench excavation that may occur through the course of construction. The Contractor shall make his own determination of the amount of shrinkage that will occur. G. The subgrade,all embankments and subcuts shall be compacted using the Quality Compaction Method. H. If the subgrade is unstable and the instability is due to excessive moisture,the subgrade shall be scarified and dried over a reasonable time period. When the material has reached acceptable moisture limits,the material shall be returned and compacted into place to the proper elevation. If the material continues to be unstable,the Engineer may authorize the removal of the undesirable material as subgrade excavation. 3.2 SOURCE QUALITY CONTROL A. The Contractor shall arrange for having the following testing performed: 1. One(1)gradation test per each 500 tons or 275 cubic yards(CV)of select granular borrow. 2. One(1)gradation test for stabilizing aggregate. B. Samples for testing shall be taken from material in stock at locations approved by the Engineer.All sampling methods shall be approved by the Engineer. 3.3 FIELD QUALITY CONTROL City of Elk River-R13.119052 EXCAVATION AND EMBANKMENT August 2019 PAGE 02330-3 V122717©Bolton&Menk,Inc.2019,All Rights Reserved