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

Marking planting area
Source: City of Troy
Maintenance
Properly designed and installed bioretention areas require
some regular maintenance, most within the first year or
two of establishment. Less maintenance is required when
the native perennial vegetation becomes established.
1. Water vegetation at the end of each day for
two weeks after planting is completed. Newly
established plants should continue to receive
approximately one inch of water per week
throughout the first season, or as determined by the
landscape architect.
2. While vegetation is being established, pruning
and weeding may be required. Weeds should be
removed by hand.
3. Organic material may also need to be removed
approximately twice per year (typically by hand).
4. Perennial plantings may be cut down at the end of
the growing season to enhance root establishment.
5. Mulch should be re-spread when erosion is evident
and replenished once every one to two years or
until the plants begin to fill in the area and the space
between plants is minimized.
Watering newly established vegetation
Source: City of Troy
Planting Tip
When planting your bioretention area, it is usually
helpful to mark the different planting areas. An
effective method is using spray paint and flags to
mark designated areas. This is especially helpful
when utilizing volunteers.
6. Bioretention area should be inspected at least two
times per year for sediment buildup, erosion, and
to evaluate the health of the vegetation. If sediment
buildup reaches 25 percent of the ponding depth,
it should be removed. If erosion is noticed within
the bioretention area, additional soil stabilization
measures should be applied. If vegetation appears
to be in poor health with no obvious cause, a
landscape specialist should be consulted.
7. Bioretention vegetation may require watering,
especially during the first year of planting. Ensure
the maintenance plan includes a watering schedule
for the first year, and in times of extreme drought
after plants have been established.
8. Bioretention areas should not be mowed on a
regular basis. Trim vegetation as necessary to
maintain healthy plant growth.
Winter Considerations
Use salt-tolerant vegetation where significant snowmelt
containing deicing chemicals is expected. The use
of sand, cinders, and other winter abrasives should be
minimized. If abrasives are used, additional maintenance
may be required to remove them in the spring.
Bioretention soils can be expected to resist freezing
and remain functioning for most of the year (although
biological pollutant removal processes will be reduced
during winter). Bioretention areas can even be used for
snow storage assuming this will not harm the vegetation.
Pipes, inlets, overflow devices, and other stormwater
structures associated with bioretention should be
designed according to general guidance on cold climate
construction.
Cost
Bioretention areas often replace areas that were intensively
landscaped and require high maintenance. In
addition, bioretention areas can decrease the cost for
stormwater conveyance systems on a site. Bioretention
areas cost approximately $5-7 per cubic foot of storage
to construct.
LID Manual for Michigan – Chapter 7 Page 145