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' 'MISC#4\FILES\9750SPEC Page 7 of 22 1. When specified, the down "logs" shall be installed prior to be bed material. Caution - Do not place FRP tanks on concrete slabs, timbers, beams, cradles or grout the tanks in wet cement. The tank, whether tied down or not, must never be left on the bed without a backfill to the top of the tank if there is any chance of water, 12" or more above the tank bottom, in the hole. 1. 5 OBSERVATION WELLS A. If shown on drawings, two slotted observation wells in opposite corners of the tank hole, are to be installed: Sample wells are to be positioned in the hole prior to placing the bedding material and supported to remain vertical during backfill. Bottom of observation well is to be 12" minimum below the bottom of tanks. Top of pipe to terminate in 12" diameter fillbox. Slotted observation wells shall be provided byh General Contractor, unless otherwise instructed by Company Rep. 1. 6 TANK HOLE LINER A. Contractor is to provide a Filter Fabric Tank Hole Liner when: 1. Tank hole is unstable soil , as defined above, or 2 . Specified by Company Rep. The entire tank hole (sides and bottom) shall be covered. Lay the fabric with 2 foot minimum overlaps. 3 . Bedding material, tie-down "logs" and sample wells are to be placed on the top of the filter fabric. Excess fabric at the top of the hole should be folded over the backfill material at subgrade level . B. APPROVED FILTER FABRIC MATERIAL: Dupont "Typar" Spunbound Polypropylene - Style 3401 Phillips Fibers Corp. - "Supac" Fabric Monsanto - "Bidim" C22 or approved equals 1. 7 BALLAST A. Water is to be used as ballast under all conditions where ballast is required. 1. DRY HOLE CONDITION: Tanks, with backfill to top of tanks, must be ballasted if there is any chance that surface of subsurface water will enter the tank hole to a depth of 23" or greater above the bottom of the tanks. Caution - Do not ballast tanks until backfill is to top of tanks.