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( as provided in 120 - 6 . 2 . 2 ) , compact the top 6 inches (compacted thickness ) of such layer to the density as specified in 120 -9 . 5 . 120 -7 . 2 . 4 Compaction Where Plastic Material Has Been Removed : Where unsuitable material is removed and the remaining surface is of the A-4 , A- 51 A- 6 , or A- 7 Soil Groups , as determined by the Engineer, compact the surface of the excavated area by rolling with a sheepsfoot roller exerting a compression of at least 250 psi on the tamper feet , for the full width of the roadbed ( subgrade and shoulders ) . Perform rolling before beginning any backfill , and continue until the roller feet do not penetrate the surface more than 1 inch . Do not perform such rolling where the remaining surface is below the normal water table and covered with water . Vary the procedure and equipment required for this operation at the discretion of the Engineer . 120 -7 . 2 . 5 Compaction of Material To Be Used In Base , Pavement , or Stabilized Areas : Do not compact embankment material which will be incorporated into a pavement , base course , or stabilized subgrade , to be constructed as a part of the same Contract . 120 -7 . 2 . 6 Compaction of Grassed Shoulder Areas : For the upper inch layer of all shoulders which are to be grassed , since no specific density is required , compact only to the extent directed . 120 -7 . 2 . 7 Compaction of Grassed Embankment Areas : For the outer layer of all embankments where plant growth will be established , do not compact . Leave this layer in a loose condition to a minimum depth of 6 inches for the subsequent seeding or planting operations . 120 -7 . 3 Compaction of Subgrade : If the plans do not provide for stabilizing , compact the subgrade in both cuts and fills to the density specified in 120-9 . 5 . For undisturbed soils , do not apply density requirements where constructing narrowwidening strips or paved shoulders 5 feet or less in width . Where trenches for widening strips are not of sufficient width to permit the use of standard compaction equipment , perform compaction using vibratory rollers , trench rollers , or other type compaction equipment approved by the Engineer . Maintain the required density until the base or pavement is placed on the subgrade . 120-8 Backfilling Around Structures and Pipe. 120 -8 . 1 Requirements for all Structures : 120 -8 - 1 . 1 General : Backfill around structures and pipe in the Dry whenever normal deAtering equipment and methods can accomplish the needed dewatering . 129 -8 . 1 . 2 Equipment and Methods : Provide normal dewatering equipment including , but not limited to , surface pumps , sump pumps , wellpoints and header pipe and trenching/digging machinery . Provide normal dewatering methods including , but not limited to , constructing shallow surface drainage trenches/ditches , using sand blankets , perforated pipe drains , sumps and siphons . 120 -8 . 1 . 3 Backfill Materials : Backfill to the original ground surface or subgrade surface of openings made for structures , with a sufficient allowance for settlement . The Engineer may require that the material used for this backfill be obtained from a source entirely apart from the structure . Do not allow heavy construction equipment to cross over culvert or storm sewer pipes until placing and compacting backfill material to the finished earthwork grade or to an elevation at least 4 feet above the crown of the pipe . 26 Technical Specifications F :\Public Works\ENGINEERING DIVISION PROJECTS\0744-8th St-US1 to 6th Ave\Admim\bid documents\0744 CONTRACT DOCUMENTS\Technical Specifications .doc