INSTALLATION | Keystone Standard & Compac Units
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STEP ONE: Prepare the base leveling pad.
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| Remove all surface vegetation and debris. Do not use this material as backfill. After selecting the location and length of the wall, excavate the base trench to the designed width and depth. Start the leveling pad at the lowest elevation of the wall. Level the prepared base with 6" of well-compacted granular fill (gravel, road base, or 1/2" to 3/4" [13 - 20 mm] crushed stone). Compact to 95% Standard Proctor or greater. Keystone recommends additional trench depth for below grade placement of Keystone units on a ratio of 1" (25 mm) below grade for each 8" (200 mm) of wall height above grade (to a maximum of 3 units buried). This lowers the base course below grade locking the wall in place and also helps prevent erosion and scouring at the base of the wall. The base trench should be wide enough to allow for the Keystone unit and drainage zone. An option to a compacted, granular material leveling pad is to use a non-reinforced concrete leveling pad. In some cases, contractors find this is a time-saving approach. Walls built to a level condition on a sloping grade require a stepped base. It is best to work out the stepped base as the wall steps up in elevation. If a concrete leveling pad is used, the step-up height needs to exactly match the Keystone unit height. |