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5.3. WET -HOLE INSTALLATION 5.3.1. Follow the dry -hole installation instructions (in section 5.2) with the modifications listed. 5.3.2. Perform points 5.2.1 through 5.2.4 of the dry -hole installation instructions. 5.3.3. Before performing point 5.2.5 of the dry -hole installation instructions, pump waterfrom the excavation hole and continue pumping to maintain minimum water level during tank installation. • Attempt to maintain the water level below the top of the bedding materials until the tank can be fully backfilled and ballasted. 5.3.4. Proceed with points 5.2.5 through 5.2.9 of the dry -hole installation instructions. 5.3.5. Proceed with points 5.2.10 through 5.2.12 of the dry -hole installation instructions. 5.3.6. In high-water conditions, where it is not possible to maintain the water level below the top of the bedding material during the entire installation, partially ballast the tank to firmly seat the tank into the bedding material and to keep it from floating. See section 5.5 for instructions. 5.3.7. The ballast level in the tank must either be lower than the backfill material or less than 12 inches [30 cm] above the water level in the hole. See Figure 5-2. 5.3.8. Proceed with points 5.2.13 through 5.2.23 of the dry -hole installation instructions. 5.3.9. Ballast the tank once the backfill is even with the top of the tank. See section 5.5. 5.3.10. Proceed with points 5.2.25 through 5.2.30 of the dry -hole installation instructions. 5.4. BOTTOM SUMPS AND FITTINGS 5.4.1. GENERAL 5.4.1.1. When handling a tank with a bottom sump orfitting, always take extra care so that the bottom sump orfitting is not damaged by contact with any other object, such as the truck bed or the ground. NOTE: During transportation and at the jobsite, tanks with bottom sumps must be cradled to avoid damage caused by allowing the tank to rest on the sump. 22 5.4.1.2. When installing a large bottom sump in a water or wastewater tank, see the Large Bottom Sump Installation Instructions supplement. See the Introduction for details on where to obtain this supplement. NOTICE All connections to the tank must be flexible. Provisions must be made to accommodate movement and misalignment between the piping and the tank. Failure to do this could result in damage to the tank and/or surrounding property. 5.4.1.3. While preparing the backfill bedding, dig a hole in the bottom of the excavation that is large enough to accommodate the bottom sump orfitting. 5.4.1.4. When installing a UL -or ULC -label tank equipped with a bottom sump, excavation and bedding must be modified to provide a 12 -inch -deep [30 -cm -deep] by 24-i nch-dia meter [61 -cm-diameter] hole centered at the sump location. 5.4.1.5. The required 12 inches [30 cm] of backfill bedding on the bottom of the excavation must also be present in the excavation hole in which the bottom sump orfitting will be placed. 5.4.1.6. Afterthe tank is placed, manually tamp backfill in the void surrounding the sump prior to adding backfill around the tank. 5.5. BALLASTING TANKS (ADDING LIQUID) A WARNING Inertthe tank and use inert gases (not air) to pressure testa tank that contains or has contained flammable or combustible liquids orvapors. Failure to follow this warning could result in an explosion, and could result in death or serious injury. A WARNING If flammable or combustible product is used as ballast, exercise special care in handling. Safeguard against sparks, fire or product spills. Failure to follow this warning could result in a fire or an explosion, and could result in death or serious injury. A WARNING The tank must be adequately vented to prevent the development of vacuum or pressure when filling or emptying the tank. Failure to properly vent the tank could cause tank failure, and could result in death or serious injury. S.S.I. GENERAL 5.5.1.1. Typically, tanks should be pressure tested before ballasting. • Do not use atmospheric air when testing pressure -testable tanks that have held flammable or combustible product. • Use nitrogen or other inert gas when testing these tanks. 5.5.1.2. For most anchoring systems, a tank is not adequately protected against flotation until the tank is fully backfilled and the top slab is in place. Therefore, during the installation process, the tank should be ballasted completely after the backfill is at least 75 percent of the way up the tank and after postinstallation testing has been successfully completed. 5.5.1.3. Only under wet -hole conditions should ballast be added before the backfill is 75 percent of the way up the tank. See section 5.3. 5.5.1.4. Care must be taken so that the use of ballast does not contaminate the product being stored. This is especially important for potable water, chemical and diesel exhaust fluid (DEF) tanks.