CASE STUDIES - Low Impact Development and Sustainable Stormwater Management - page 213

stormwater management approaches were developed during the 1990s and into
the 2000s, especially in Philadelphia. The end result of this effort is very close
to the LID program advocated statewide, although the design criteria used were
intended to control sufficient runoff volume to prevent CSO discharges and are
less strict numerically.
B.3 LID MANUAL FOR MICHIGAN (2008)
In 2007-2008, Cahill Associates assisted the Southeast Michigan Council of
Governments (SEMCOG) in the preparation of the LID manual for the state of
Michigan. Focused initially on the six counties in the southeastern portion of the
state, which is the most highly urbanized portion of the state and includes the
metropolitan region of Detroit. The manual was supported by a state grant which
required that the guidance be representative of the entire state, and set the bar for
both new development and redevelopment, an important issue in the older urban
communities.
This manual focused exclusively on volume-reduction designs and was tailored
to the specific hydrology of Michigan, a glacially sculpted landform that produces
a regional hydrology with low base flow and significant natural soil infiltration
in many regions. The best example of this approach is contained in Chapter 2
of this manual, included here as the most comprehensive LID manual developed
as of 2008. The writing style (largely by SEMCOG staff) is produced in a form
easily understood by the nontechnical community and is well illustrated in color.
It is also available in electronic form. It is far superior to earlier manuals.