Division 2 - Site Work
     Section 02200 - Excavation and Earthwork

image 3: Site excavation and earthwork.

Note that images 3 & 4 show a condition at the South border of the site, which required zero lot line excavation. There are many options for this kind of site excavation. The one specified was steel tiebacks secured to un-excavated soil and rock. The tiebacks are further secured to steel bearing plates, which spread the load of the overturning vertical face of the excavation which has been stabilized by a "shotcrete" concrete coating which is directly applied to the vertical surface of the excavation.

image 4: Shoring of excavation with tie backs and shotcrete.

Image 4 clearly shows the excavation, tie back, and shotcrete procedure. If you look carefully at the horizontal lines of the vertical wall you can deduce how excavation proceeded in approximately 5 ft increments. Following this procedure which is dictated by the soils ability to remain stable, shotcrete and tiebacks are installed immediately. The construction procedure is then continued until the desired depth is reached. The tiebacks and shotcrete are lost formwork and will be buried during back fill and compaction procedures. The 5 ft increment coincides with OSHA's maximum trench excavation without supported and braced sides. Note the temporary construction fence and pylons at the street and the importance of maintaining this protection during the construction process.

Division 2
Page 2 

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