2008-342C - Laserfiche WebLink

Home Browse Search

Indian River County File No . 06 - 5699 -6- 4 . 4 Construction Considerations Roadway construction should be performed in accordance with the appropriate sections of the current edition of the Florida Department of Transportation ( FDOT ) Standard Specifications for Road and Bridge Construction . In accordance with these specifications , the removal of any organic materials (A-8 soils ) including topsoil as encountered , and any plastic (A-2-6 and A-2-7 ) and high plastic soil should be accomplished in accordance with FDOT Standard Index 500 unless otherwise indicated on the plans . Backfill should generally consist of select material (A-3 and A-24 ) compacted in accordance with Section 120-9 of the Standard Specifications . In-place density tests should be performed on the fill soils to verify the specified degree of compaction . The minimum density test frequency should be in accordance with the FDOT Materials , Sampling , Testing , and Reporting Guide . Fill Placement and Side Slopes for Embankment Construction are presented in the FDOT Standard Index 505 . As mentioned above , A-24 type soils and hardpan -type soils will likely be encountered along much of the alignment within the upper 6 feet ( referenced from existing ground surface ) . The A-24 type soils can be used for roadway construction using strict moisture control ( in - place moisture near optimum moisture content as determined by the Proctor test) . Special compaction equipment ( i . e . , sheepsfoot-type rollers , etc . ) and allowing time for the material to dry sufficiently may also be needed to use these soils in construction . If A-24 soils excavated from below the groundwater table are to be used for embankment fill , we recommend stockpiling the excavated clayey/silty soils as high as possible so as to increase the rate of drainage . Prior to their use , the - soils should be spread out and disced to further reduce moisture levels . Nevertheless , soil with high percentage of fines will be slow in draining and may present problems during compaction efforts . We note that the weakly-cemented , hardpan-type soils can be problematic for several reasons . Hardpan can be difficult to excavate , often requiring special equipment ; especially in confined excavations such as utility trenches . Excavated hardpan -type soils are often cobble to boulder-size chunks of cemented soils which are not easily broken down for re-use as structural fill . In addition , when pulverized into fragments that can be compacted to an adequately dense matrix, the in -place soil often fails the relative compaction test because during laboratory preparation , the soil is pulverized into smaller particles , resulting in a denser laboratory matrix than that which can be achieved in the field . Alternative acceptance criteria may need to be used for hardpan-type soils used as fill . This criteria would need to be developed on a site specific basis after observing the contractor' s earthwork methodology and the nature and condition of the compacted hardpan -type soils . Should any water-filled canals or ditches be reclaimed (or filled ) for roadway construction , we recommend conducting further explorations relative to the soils beneath and within the canals , including additional soil borings and canal bottom probes . We also recommend that the designer add notes to the plans relative to potential difficulty in dewatering , using strict moisture control and any special compaction equipment for A-2-4 soils , maintaining positive site drainage , excavation of hardpan -type soils and wrapping pipe joints .