Low Impact Development Manual for Michigan - OSEH - University ...

Applications
Soil restoration can occur anywhere to alleviate soil
compaction. It can be specifically addressed in the
following examples:
• New development (residential, commercial,
industrial) – Heavily compacted soils can be
restored prior to lawn establishment and/or
landscaping to increase the porosity of the soils and
aid in plant establishment.
• Detention basin retrofits – The inside face of
detention basins is usually heavily compacted, and
tilling the soil mantle will encourage infiltration to
take place and aid in establishing vegetative cover.
• Golf courses – Using compost as part of
landscaping upkeep on the greens has been shown
to alleviate soil compaction, erosion, and turf
disease problems.
Design Considerations
1. Tilling the soil (also referred to as scarification,
ripping, or subsoiling)
a. Effective when performed on dry soils.
b. Should be performed where subsoil has become
compacted by equipment operation, dried out,
and crusted, or where necessary to obliterate
erosion rills.
c. Should be performed using a solid-shank ripper
and to a depth of 20 inches, (eight inches for
minor compaction).
d. Should be performed before amending media is
applied and after any excavation is completed.
e. Should not be performed within the drip line
of any existing trees, over underground utility
installations within 30 inches of the surface,
where trenching/drainage lines are installed,
where compaction is by design, and on
inaccessible slopes.
f. The final pass should be parallel to slope
contours to reduce runoff and erosion.
g. Tilled areas should be loosened to less than
1,400 kPa (200 psi) to a depth of 20 inches
below final topsoil grade.
h. The subsoil should be in a loose, friable
condition to a depth of 20 inches below final
topsoil grade and there should be no erosion rills
or washouts in the subsoil surface exceeding
three inches in depth.
i. Tilling should form a two-directional grid.
Channels should be created by a commercially
available, multi-shanked, parallelogram
implement (solid-shank ripper), capable of
exerting a penetration force necessary for the
site.
j. No disc cultivators, chisel plows, or springloaded
equipment should be used for tilling.
The grid channels should be spaced a minimum
of 12 inches to a maximum of 36 inches apart,
depending on equipment, site conditions, and the
soil management plan.
k. The channel depth should be a minimum of 20
inches or as specified in the soil management
plan. If soils are saturated, delay operations
until the soil, except for clay, will not hold a ball
when squeezed.
l. Only one pass should be performed on erodible
slopes greater than one vertical to three
horizontal.
2. Applying soil media for amendment
a. Soil media should not be used on slopes greater
than 30 percent. In these areas, deep-rooted
vegetation can be used to increase stability.
b. Soil restoration should not take place within the
critical root zone of a tree to avoid damaging the
root system. (Where one inch of tree trunk DBH
is equal to one foot of soil area on the ground
away from the tree trunk.)
c. Onsite soils with an organic content of at least
five percent can be stockpiled and reused to
amend compacted soils, saving costs. Note:
These soils must be properly stockpiled to
maintain organic content.
d. Soils should generally be amended at about a
2:1 ratio of native soil to media. If a proprietary
product is used, follow the manufacturer’s
instructions for the mixing and application rate.
LID Manual for Michigan – Chapter 7 Page 285