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