Laserfiche WebLink
and reduced pavement life. Sloping the pavement surfaces above the groundwater levels and <br />direct water away from the pavement surfaces can aid in reducing the potential for water to <br />accumulate below the pavement section and potentially reduce the effects of frost heave. The <br />clayey subgrade soils (CL, CL-CH) are impermeable for practical purposes. Because of that you <br />may wish to consider using a 12 to 18-inch-thick drained sand sub -base below the aggregate base <br />course to reduce the potential effects of frost heave. <br />Laboratory Moisture Contents Laboratory moisture content of the clayey soils ranged from about <br />181/2 to 53 percent indicating that the clayey soils were likely above their assumed optimum soil <br />moisture content. Clayey soils that will be reused as fill or backfill may need to moisture <br />conditioned (dried) to meet the recommend compaction levels. Clayey soils that cannot be dried <br />and recompacted may need to be removed and replaced with suitable compacted engineered fill. <br />Summer months are typically more favorable for drying wet clays. <br />Groundwater Groundwater was encountered in 6 of the soil borings at depths ranging from about <br />7 1/2 to 10 feet below the ground surface. We do not anticipate that groundwater will be <br />encountered during pavement construction/reconstruction or culver installation, if any, and we <br />do not anticipate that dewatering will be required. <br />4.3 Utility Recommendations <br />We anticipate that new culvert and/or storm sewer utilities could be installed as part of this <br />project. We further anticipate that new utilities will bear at depths about 5 feet below the ground <br />surface. At these depths, we anticipate that the pipes will bear on sandy or clayey soils or <br />compacted engineered fill which in our opinion are suitable for pipe support. We recommend <br />removing all vegetation, topsoil and any soft or otherwise unsuitable soils, if any, beneath utilities <br />prior to placement. <br />We assume that open cut excavation techniques will be used for pipe installation. We further <br />assume that typical excavations depths will be on the order of 5 feet below the ground surface. At <br />typical 1:1 excavation backslopes, the excavation will extend about 5 feet beyond the edge of the <br />excavation. The excavation may extend into/onto adjacent properties or the adjacent roadways <br />posing a risk of undermining structures on those properties or roadways. In addition, the soils <br />could slough as they are excavated resulting in side slopes flatter than 1:1 further increasing the <br />horizontal limits of the excavation. If site constraints will limit the excavation, trench boxes or <br />temporary shoring may be required. <br />Backfilling We understand that in most cases new pavements will be constructed over the top <br />of the utility trench(s) and that soil excavated for pipe installation will be placed back in the <br />excavations, to the greatest extent possible. The sandy and clayey soils encountered in the borings <br />are generally suitable for reuse as fill or backfill. As noted above the clayey soil were likely above <br />their assumed optimum moisture content and will likely need to be moisture conditioned (dried) <br />to meet the recommended compaction levels <br />If encountered, we do not recommend re -using topsoil, buried topsoil, organic soils or soils that <br />are black in color for pipe support or for fill or backfill below roadways. It may be possible to re- <br />use these materials in "green areas", if any. <br />10 <br />