image 5: Excavation and earthwork as a benched procedure.
Division 2 - Site Work
Section
02200 - Excavation and Earthwork
image 5: Excavation and
earthwork as a benched procedure.
These images show benched excavation procedures. Benched excavation requires more space than a tieback and shotcrete wall excavation. This excavation was possible on the East and North sides of the site. Image 5 shows a backhoe benching the excavation in approximately 10 ft increments. The natural angle of repose of this soil was established during subsurface investigation (Division 1) and therefore the extent of the benched excavation was calculated to fall within the construction fence at the most extreme condition (the site dropped approximately 30 ft in elevation from SE to NW. The determination for the procedure is the responsibility of the Contractor. Site removal of excavated material shown here is specified under Section 02115 of this Division.
image 6: Soil erosion control measures & dewatering.
Image 6 shows a filter fabric placed on the bottommost bench for preventing soil and fine particles from entering the gravel backfill which is placed above and around the footing drains. Note the two blue PVC pipes which emerge from the gravel backfill. These are connected to deep cisterns and pumps as a dewatering procedure for excavation. The NE end of the site is the location of the lowest substructure which enters the water table and required dewatering procedures (Division 1; Section - C; 1C-21d. Site Dewatering and Erosion Control).
Division 2
Page 3
Copyright ©2001
_____________
URL:
http://__________________/D2-3.htm
