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The above earth pressures should be considered as equivalent fluid pmssureg, and actual pressures <br />with'a factor of safdty equal to one. 'As a result; shoring design should include an appropriate <br />factor of safety for the overall system. <br />The above values are also based on drained conditions (no hydrostatic or buoyant conditions) and <br />the assumption that the wall is vertical (no batter). <br />Surcharge loads (dead or live) should be added to the indicated lateral earth pressures. Surcharge <br />pressures should be applied as a uniform (rectangular) pressure. When evaluating lateral <br />resistance (passive resistance), the top foot of soil should not be included in the evaluation unless <br />the ground'stirface is paved. Vertical surcharges set behind the wall horizontally, a distance <br />greater than the exposed wall height, need not be added to the design pressures. Surcharge <br />pressures due to concentrated loads may be evaluated after geometric constraints and loading <br />conditions are determined. <br />Due to the relatively close proximity of the tank excavation to the canopy, consideration should be <br />given to the installation of the storage tanks and placement of tank backfill prior to the installation <br />of canopy footing and/or erection of the canopy structure. If canopy erection is performed prior to <br />placement of tank backfill, special construction procedures may be necessary to ensure adequate <br />support of the footing until the tank backfill is in place. <br />6.7.4 Tank Backfill <br />Backfilling adjacent to and over the top of the underground storage tanks, should be performed in - <br />accordance with the tank manufacturer's requirement. <br />If gravel is used for tank backfill, in lieu of compacted soil backfill, the contact between the gravel <br />and the native soil should be lined with geofabric and the backfill should be covered with a <br />structural concrete slab designed to bridge over localized settlement of the gravel backfill. <br />Tentative pavement structural sections were evaluated based upon the results of laboratory <br />R -Value testing and evaluation of the anticipated traffic loading, and are presented below. <br />IN 40007.095-01 <br />ftVnsw197-06-4traygeo.doc <br />6-5 <br />