ARCHIVED REPORTS XR0011655 - Laserfiche WebLink

Home Browse Search

1� LEINFELDER i evaluate the subsurface conditions to be encountered within the pipeline alignment in order to make a selection of equipment and techniques 53 Bedding and Backfill General Trench backfill and pipe bedding should be performed in accordance with the City of Stockton and San Joaquin County requirements, the requirements of other jurisdictional agencies, and/or Pipe manufactures requirements The project Civil Engineer should develop the final specifications and project details based on the pipe type, bedding conditions and other factors beyond the scope of this study The following presents general guidelines and recommendations for earthwork operations Foundation Maternal Prior to placement of bedding material, the exposed soils at the bottom of trench and jacking pit excavations should be proof rolled to detect soft, pliant, loose, or otherwise disturbed soils If detected, these soils should be scarified to a depth of at least 8-inches or to the depth of unstable sods, whichever is greater, un1f� moisture-conditioned or dried to between 1 and 4 percentage points above the optimum moisture content, and compacted to at least 90 percent of the maximum dry density . As an alternative, the unstable soils should be removed and replaced with bedding material conforming to the specifications presented in the following section All excavations resulting from removal activities should be cleaned of loose or disturbed material and dish-shaped with sides sloped 3(h) 1(v) or flatter to permit access for compaction equipment Where the excavation extends below groundwater into wet clays and sands, the bedding material at the foundation level should be wrapped entirely with geotextile fabric, such as Mirafi 140N or equivalent substitute Trench and Jading Pit Backfill Trench backfill and bedding placed within existing or future city or county right-of-ways should meet or exceed the requirements outlined in the current city and county specifications Trench backfill or bedding placed outside existing or future right-of-ways could consist of native or imported soil which meets the requirements for f 11 material provided below However, coarse-grained sand and/or gravel should be avoided for pipe bedding or trench zone backfill unless the material is fully enclosed in a geotextile filter fabric, such as Mirafi 140N or an equivalent substitute In a very moist or saturated condition, fine-grained sod can migrate into the coarse sand or gravel voids and cause "loss of ground" of differentiae settlement along and/or adjacent the trenches, thereby leading to pipe joint displacement and pavement distress • i 13629 G01/2002R369 2002 K1einfelder Inc aprii 19 '002 Pasze 9 or 16