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

then weightings of potential development also
may be established, varying with lack of degree of
sensitivity measured by the resources themselves or
overlapping of resources.
4. Municipal regulation
The level of regulation imposed on resource
areas (primary and secondary) will likely vary by
municipality. A municipal ordinance may prohibit
and/or otherwise restrict development in primary
and secondary resource areas, provided certain
legal tests (such as a takings determination) are
passed. Additional activities include:
1. Conservation easement – Given to land
conservancy or maintained by homeowners
association.
2. Requirements in the master deed and bylaws for
protection and preservation.
3. Boundary markers at edges of lots to minimize
encroachment.
4. Cooperative agreements for stewardship
of sensitive areas between homeowners’
associations and local conservation
organizations.
Stormwater Functions and
Calculations
Any portion of a site that can be maintained in its
presettlement state by using this BMP will not contribute
increased stormwater runoff and will reduce the
amount of treatment necessary. Calculation methodology
to account for this BMP is provided in Chapter 9.
Volume
Protected sensitive areas are not to be included in the
disturbed stormwater management area when calculating
runoff volume (Chapter 9 and Worksheet 3).
Any portion of a sensitive area that is mitigated or
revegetated/reforested should be included in the
disturbed stormwater management area, but may be
granted credit in accordance with the applicable BMP
for native revegetation, soil restoration, minimize soil
compaction, riparian buffer restoration, or minimize
total disturbed area.
Peak rate
Runoff from the protected sensitive area may be
excluded from peak rate calculations for rate control,
provided that the runoff is not conveyed to and/or
Potential development area map
Source: Arndt, Randall G. 1997.
through stormwater management control structures. If
necessary, runoff from protected sensitive areas should
be directed around BMPs and stormwater pipes and
inlets by means of vegetated swales or low berms that
direct flow to natural drainageways.
Water quality improvement
Water quality is benefited substantially by avoiding
negative impacts which otherwise would have resulted
from impacts to sensitive areas (e.g., loss of water
quality functions from riparian buffers, from wetland
reduction, etc.).
Construction Guidelines
Although protecting sensitive areas happens early
in the site plan process, it is equally important that
the developer and builder protect these areas during
construction.
The following guidelines describe good planning practices
that will help ensure protection of a few common
environmentally sensitive resources during construction.
Water resources
• If vegetation needs to be reestablished, plant native
species, or use hydroseed and mulch blankets
immediately after site disturbance.
• Use bioengineering techniques, where possible, to
stabilize stream banks.
LID Manual for Michigan – Chapter 6 Page 102