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1.3.1.5. For additional requirements and specifications, consult all codes and regulations of governmental agencies. See the Introduction for additional information. 1.3.2. EXCAVATION AND TANK LOCATION 1.3.2.1. We recommend that the tank owner seek the advice of a local foundation professional engineer to determine the proper placement of a tank excavation near any existing structure(s). NOTICE Improper placement of the excavation could result in damage to the tank and/or property damage. 1.3.2.2. The tank owner and/or the owner's technical representative is responsible for determining the proper placement of a tank excavation. 1.3.2.3. In general terms, the size of the excavation is determined by: • the number of tanks to be installed • the size of the tanks to be installed 1.3.2.4. The location of a tank can be affected by the location of nearby structures. When selecting a tank site, care must be taken to avoid undermining the foundations of existing structures or new buildings to be constructed. See Figure 1-1. • Ensure that downward forces from loads carried by the foundations and supports of nearby structures (constructed before or after tank installation) are not transmitted to the tanks. 1.3.2.5. Typically, the way to check the placement of the tank in relationship to a nearby structure is to do the following: • determine the depth of burial needed for the tank • locate the footing of the structure to be considered • determine the line that would fall into the ground from a 45 -degree angle drawn downward from the corner(s) of the footing of the foundation that is closest to the tank M 1.3.2.6. The tank must not fall within the "shadow" of the 45 -degree angle line drawn from the foundation's footing. See Figure 1-1. If the tank would fall within this "shadow;' do one of the following to ensure that the tank does not fall within the "shadow": • move the tank away from the existing building • move the foundation of the building to be constructed away from the tank • deepen the footing of the planned building's foundation 1.3.3. DEPTH OF EXCAVATION 1.3.3.1. Typically, the depth of the excavation is determined by: • groundwater conditions • traffic at the site • soft or uneven excavation base • pipeline grade requirements and/or invert elevations • codes and regulations 1.3.3.2. Groundwater must be considered if the level of water in the ground may rise above the bottom of the tank at any time during the life of the tank. 1.3.3.3. Traffic loads are considered to be loadings for highway vehicles up to H-20 or HS -20 as defined in the AASHTO Standard Specifications for Highway Bridges. 1.3.3.4. Excavations must allow for 12 inches [30 cm] of backfill between the bottom of the tank and the bottom of the excavation or the top of the anchor slab (or any other stabilizing materials used). 1.3.3.5. If either an anchor slab or other stabilizing material is used, allow additional depth in the excavation to accommodate their construction. 1.3.3.6. Typically, no additional depth of bedding is required for the use of a deadman anchoring system. 1.3.4. DEPTH OF COVER A CAUTION In both traffic and nontraffic installations, no truck or equipment loads are allowed over the tank until the backfill is at least at the depth of cover specified in Table 1-1 or Table 1-2, whichever is applicable. Failure to follow this caution could result in minor or moderate injury, and/or damage to the tank. 1.3.4.1. We recommend that every site be thoroughly evaluated for the potential of a rise in the local water table or of trapped water (a wet -hole condition). Sufficient overburden and/or an appropriate anchoring system must be present to offset buoyancy of the tank in such conditions. NOTICE Failure to provide sufficient overburden and/or an appropriate anchoring system could cause tank failure, or could result in damage to the tank and/or surrounding property. 1.3.4.2. The tank owner or the owner's technical representative is responsible for determining sufficient overburden and/or appropriate anchoring system. 1.3.4.3. The minimum depths of cover dimensions given here are important to the successful installation of a tank. They may not be sufficient to counteract buoyancy in wet -hole conditions. 1.3.4.4. Additional depths of cover may be necessary due to safety requirements or operational requirements by governmental agencies.