INSTALL_2012 - Laserfiche WebLink

Home Browse Search

7.3.4.Excavations must allow for 12 inches of backfill be- tween the bottom of the tank and the bottom of the excava- Footing tion or the top of the anchor slab(or any other stabilizing materials used).See POINT 7.5.3.3.and SECTION 8.6. Shadow of .II=IIIII-11 IIIII=IIIA=VIII-VIII-IIIII_ 7.3.5.If either an anchor slab or other stabilizing material is — —' used,allow additional depth in the excavation to accomodate 45-degree angle II- _IIII€ eP -IIIII-IIIII =IIIII=IIIII=IIIII=11111-I their construction. \ _ I1-IIIII=1111- 11=1NI =will=i —Ilu=oll=lllll-ulll—u 7,3.6.Typically,no additional depth of bedding required for €IIII_III =IIII- III- I -1111- P 9 Is III=IIIII = IIIII=IIIII=IIIII=11 the use of a deadman anchoring system. Tank =11111 IIIII_IIIII IIII= 101 - I=IIII_Lil 7.4. DEPTH OF COVER 0 CAUTION In both traffic and nontraffic installations,no truck or equip- ment loads are allowed over the tank until the backfill is at the minimum specified requirements.Failure to follow this FIGURE 7-1 caution may result in minor or moderate injury,and/or dam- 7.2.4.1.Ensure that downward forces from loads carried by age to the tank. the foundations and supports of nearby structures(con- 7.4.1.Xerxes recommends that every site be thoroughly evalu- structed before or after tank installation)are not transmitted to ated for the potential of a rise in the local water table or of trapped the tanks. water(a wet-hole condition).Sufficient overburden and/or an ap- 7.2.5.Typically,the way to check the placement of the tank in propriate anchoring system must be present to offset buoyancy of relationship to a nearby structure is to do the following: the tank in such conditions. 7.2.5.1.Determine the depth of burial needed for the tank. CAUTION 7.2.5.2.Locate the footing of the structure to be considered. Failure to provide sufficient overburden and/or an appropri- ate anchoring system may cause tank failure,or may result 7.2.5.3.Determine the line that would fall Into the ground from in damage to the tank and/or surrounding property. a 45-degree angle drawn downward from the comer(s)of the footing of the foundation that is closest to the tank. 7.4.2.The tank owner or the owner's technical representative is responsible for determining sufficient overburden and/or ap- 7.2.5.4.The tank must not fall within the"shadow"of the propriate anchoring system. 45-degree-angle line drawn from the foundation's footing. See FIGURE 7-1. 7.4.3.The minimum depths of cover dimensions given here are important to the successful installation of a tank.They may not 7.2.5.5.If the tank would fall within this"shadow,"do one of be sufficient to counteract bouyancy in wet-hole conditions. the following to ensure that the tank does not fall within the "shadow": 7.4.3.1.Additional depths of cover may be necessary due to federal,state or local regulations,safety requirements or oper- 7.2.5.5.1.Move the tank away from the existing building. ational requirements. 7.2.5.5.2.Move the foundation of the building to be con- structed away from the tank. In a nontraffic installation,ensure that the area above the 7.2.5.5.3.Deepen the footing of the planned building's foundation. tank is not subjected to traffic or other types of loads,which 7.3. DEPTH OF EXCAVATION could cause damage to the tank,and could result in death or serious injury. 7.3.1.Typically,the depth of the excavation is determined by: 7.4.4.Tanks not subjected to traffic must have a cover depth 7.3.1.1.groundwater conditions of 12 inches of backfill.See TABLE 7-1. 7.3.1.2.traffic at the site 7.4.5.Tanks subjected to traffic must have a cover depth of 7.3.1.3.soft or uneven excavation base one of the following: 7.3.1.4.codes and regulations. 7.4.5.1. 36 inches of backfill 7.3.2.Groundwater must be considered if the level of water in 7.4.5.2. 18 inches of backfill and 6 inches of reinforced concrete the ground may rise above the bottom of the tank at any time 7.4.5.3. 18 inches of backfill and 8 inches of asphalt. during the life of the tank. 7.4.6.See TABLE 7-1 for minimum requirements for tanks 7.3.3.Traffic loads are considered to be loadings for highway other than petroleum tanks. vehicles up to H-20 or HS-20 as defined in the AASHTO Stan- dard Specifications for Highway Bridges. 12