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5.2.12. Use the tops of the ribs to establish longitudinal level. Establish lateral level by placing the level across the top of a fitting ora manway. NOTICE Do not place straps between ribs (not applicable for 4 -foot - diameter tanks). Failure to properly place straps could result in damage to the tank. 5.2.13. If anchor straps are to be used, install them at this time. See section 1 and follow these instructions: • The locations for anchor straps are marked on tank ribs by the arrow head symbol (on the tank itself on 4 -foot -diameter tanks). • All marked anchor strap locations must have straps. • Place a strap on each marked location and install anchoring hardware. See section 1. • Tighten each anchor strap until it is snug over the rib (over the tank itself on a 4 -foot -diameter tank), but does not cause any deflection of the tank. Straps must be uniformly tight. • Al2-inch-thick [30 cm] bedding is required under the tank, even when low -profile deadmen are used. • After the straps have been installed and tightened, take a tank diameter measu rement to check tank deflection, and record it as Measurement #2 on the Tank Installation Checklist. NOTICE Overdeflection of the tank could result in damage to the tank. 5.2.14. Install bottom fittings and bottom piping on water/wastewater tanks at this time. See section 5.4. 5.2.15. Place approximately 12 inches [30 cm1 of primary backfill around the bottom of the tanks between the ribs (if present) and under the end domes. • Use a nonmetal tamping rod long enough to reach beneath the tank to push material underthe tank body and domes until solid resistance is felt. All voids must be filled and the tank must be fully supported. See Figure 5-1. NOTICE Do not use metal probes. Failure to follow this notice could result in damage to the tank. NOTICE Do not strike the tank with the tamping rod. Failure to heed this notice could result in damage to the tank. 5.2.16. Repeat point 5.2.15 with a second lift of approximately 12 inches [30 cm] of primary backfill. 5.2.17. After the second lift of material has been placed and worked under the tank, bring the backfill to the top of the tank. • Place backfill material evenly on opposite sides of the tank so that the tank does not shift. 5.2.18. If secondary backfill material is to be used on the perimeter of the installation, it must be placed and compacted at the same time as the primary backfill material. 5.2.19. During the backfilling process, it is good practice to continue to check tank deflection. NOTICE Thoroughly hand -tamp backfill to eliminate all voids under the tank. Do not allow the tank to shift during the backfill procedure. If there are voids under the tank and/orthe tank has shifted once backfilling has commenced, itwill be necessaryto remove and reinstall the tank. Failure to follow this notice could result in damage to the tank and other property damage. 5.2.20. After backfill has been brought to the top of the tank, take another tank diameter measurement. Record it as Measurement#3 in the Tank Installation Checklist, and determine whether tank deflection is within the allowable limits. 5.2.21. All UL -label, ULC -label and potable water tanks must be pressure tested after backfill is brought close to the top of the tank. 5.2.22. If additional testing (postinstallation testing for pressure - testable tanks or optional hydrostatic testing) is to be done, perform those tests now. See section 6 for instructions. 5.2.23. Typically, installers choose whether the tank should be ballasted at this time. See section 5.5 for instructions. 5.2.24. If piping and/or venting needs to be installed, complete this work now. See section 7 for instructions. 5.2.25. If containment sumps need to be installed, do that now. See section 7 for instructions. 5.2.26. Continue to backfill to grade, or to subgrade if concrete or asphalt is to be installed. 5.2.27. When the tank has been backfilled to subgrade (but before placement of slab), take the last required tank diameter measurement. • Record it as Measurement #4 and determine whethertank deflection is within the allowable limits shown in Table 1-6. • Subtract Measurement#4 from Measurement#1 and record it as the Deflection Measurement on the Tank Installation Checklist. 5.2.28. Install reinforced or unreinforced concrete/asphalt, if used, at this time. See section 1. • The cover depth must meet the appropriate minimum specified in section 1. • All backfill that is to be compacted must be compacted with a hand -guided, vibrating -plate, mechanical compactor. NOTICE Do not use rammer-type compactors over the top of the tank. Failure to follow this notice could result in damage to the tank and/or surrounding property. 5.2.29. If the tank has a monitoring system, after backfilling is completed and after top slab is in place (if used), perform necessary monitoring checks. See section 8. 5.2.30. Complete the Tank Installation Checklist 21