Installation Instructions

25
RETAINING WALLS
Please note: If you are unsure of your soil condition, consult a soils engineer.
Soils are divided into three groups:
Step 2 - Leveling Pad Installation
Place a minimum of 6" of compacted base material
and compact to 95% Standard Proctor density.
Verify that the base is level with a transit or hand
level. Be aware that the base material (commonly
referred to as road base or base aggregate) will vary
from region to region. The base material should
consist of crushed material: 3/4" crushed concrete
with nes or 3/4" crushed rock or limestone with
nes. Your material must be angular, nothing round.
Round rock will act like ball bearings and roll when
under pressure, causing the wall to bow or collapse.
Step 3 - Base Course Installation
The base course will consist of one layer of block.
Base units will have the rear lip removed before
placing on the leveling pad. Use a string line behind
the tail of the block for alignment on straight wall
applications. All blocks should rest rmly on the
pad and be centered to allow 6" of base material
in front and 6" behind the base block. Level each
block, side-to-side, front-to-back and across three
full blocks with a hand level. A rubber mallet may be
used to level and align the blocks.
Step 4 - Core and Drainage Fill
Place 3/4" to 1" clean aggregate (crushed rock)
within the cores and a minimum of 12" behind
the blocks. This creates a drainage zone and the
stone columns that help to unify and maximize the
performance of the wall. In addition, sock wrapped
perforated drainpipe can be installed at the desired
level behind the wall (usually behind the rst block
above grade). The perforated drainpipe should have
adequate slope to drain water in the right direction
towards each drainpipe outlet. Drainpipe outlets are
usually installed every 30 to 50 ft.
Granular - sands and
gravel consisting of grains
down to .002" - Best for
strength and support
Clay - very ne particles,
> 50% passing #200 sieve
-May cause settlement
Organic - loam, peat
that is made up of moss,
leaves and vegetable
matter, and topsoil -
Should be removed