14
INST
ALLA
TION MANUAL
Modular Rain Garden
Backfilling and Planting
ST
AGE 4
Once the modules have been installed,
install the observation well, if specified,
prior to commencing back fill.
Before adding bio-retention fill
materials, make sure that the site
is stabilized so that they will not
be contaminated by excessive
sedimentation in a storm event.
Backfill the excavated area outside of
the structure in 8” lifts using crushed
angular stone and backfill the interior
of the structure with the prescribed
fills (sands, aggregates, filter fabrics,
and planting soils per plan) so that the
inside and the outside of the system are
backfilled in alternating lifts. Remove
temporary shoring
Follow the plan specifications for
material types and layer thicknesses
of the bio-retention fill materials.
Do not compact the interior fills,
and consult the project designer for
recommendations regarding overfill of
the planting soils since approximately
20% more may be required to account
for natural settlement.
As you backfill the interior, install
erosion protection at the water intake
locations.
Water bio-retention materials and
allow to settle and adjust heights to
plan specifications, as required, before
adding plant materials and final mulch
layer as specified.
Place plants once soils have settled.
Add mulch layer to achieve final grade.
Step 9:
Backfilling structure.
Step 10:
Placing, Planting Soils.
Erosion control at water intake
