ABT, Inc. • PO Box 837 • 259 Murdock Road • Troutman, NC 28166
(800) 438-6057 • (704) 528-9806 • Fax: (704) 528-5478

> Trench Former > TF-14 > Installation

Trench Former Installation

Excavation

Excavation must provide for a minimum of 6 in. (150 mm) on both sides of the former and 9 in. (230 mm) on bottom. Bottom allowance includes a 3 in. (75 mm) clearance for the no-float U legs and anchoring slab. Excavate to match former numbers provided. Each 8 ft. (2.4 M) section has 3 equal length U legs, so the excavation should be a series of step-down sections.

Pre-Assembly

Lay out the former and rail sections along the excavation. Former sections should be laid out in the proper numerical sequence. Former and U legs are color-coded for easy assembly. Match color of threads on the U legs to the color of the part number marked on end of form. Attach the legs to the rails by running a nut to the end of the threads. Insert threads through opposing rail brackets and run a second nut onto the u-leg until the top of the threads are flush with the top of the nut. To tighten, bring the bottom nut up to the underside of the rail bracket. Apply the Former Release to bottom and sides of the former. Do not use a petroleum based form release — it will severely attack the foam. Spread the rails open, position the former between them and insert the flange of the rail into groove on each side of the former. Install Cross-Ties tightly across rails to ensure a snug fit and precise grate-seat dimension.

Catch Basin

When used at the end of a trench run, the last trench no-float leg is replaced by a leg which matches the length of the catch basin leg. This will insure against flotation of the deep end of the trench by securing it to the anchoring slab.

Component Placement

Begin installation at deep (outlet) end. Attach a length of supporting lumber at each 8 ft. (2.4 M) joint. Hold top of the angle rail to finished grade and attach supporting lumber to the grade stakes. To position the next section, push rail clips onto the rail ends of one section, then push rail ends of next assembled section onto these clips until the rails lock into place. When clips are locked, the sections will be butted together. To assist in longitudinal alignment, 2x4 wooden blocks can be fitted to alignment groove in the top of the former and nailed to supporting lumber once the former is in place. The U legs should be suspended just above floor of excavation. Vertical discharge piping should now be fitted to the former.

Concrete Placement

Place a concrete anchoring slab wall-to-wall and end-to-end in the bottom of the excavation, covering the U legs with 2 in. (50 mm) of concrete. Allow this slab to set hard, then remove supporting lumber. Monopour trench bottom and walls, vibrating at the rails for good consolidation. While finishing concrete, remove Cross-Ties by cutting in half, turning the cut sections 90° and lifting them out.

Deforming

After 24 hours, you can deform the trench. Drive a pry bar between former and trench floor exerting upward force. The center V-shaped section will break free and can be easily removed. Remaining pieces of former can then be pulled from the trench walls.

Note: For more detailed instructions and for custom Trench Former installations, please see the ABT "Trench Former Installation Guide".