The provisions set forth in this chapter have been set forth
in order to assist in compliance with the Federal Phase 2 National
Pollutant Discharge Elimination System (NPDES) stormwater regulations,
which are and will be administered by the State of Michigan. This
administration is authorized by Michigan Public Act 451 of 1994, as
amended, Part 31. The City of Monroe is subject to the requirements of this
Act and has been issued a jurisdictional general permit for discharges
from its municipal separate storm sewer system (MS4). Provisions of
this chapter are set forth to establish requirements for the management
of stormwater from new development and redevelopment throughout the
City of Monroe to ensure consistency with state and federal regulations
and administrative rules.
The requirements of this chapter shall apply to all new and
redeveloped sites with projects that disturb one acre or more, including
projects of less than one acre that are part of a larger common plan
of development or sale that would disturb one acre of more. These
requirements shall apply to all public and private sites within the
City of Monroe, regardless of whether the stormwater outlet(s) from
the site discharge to a designated county drain, City storm sewer
system, waters of the state or any other type of conveyance. These
requirements shall also apply to sites under the control of public
agencies such as schools, federal and state governmental facilities,
and other entities that might not otherwise be subject to site plan
procedures and requirements set forth in other sections of the City's
codified ordinances.
All sites subject to the provisions of this chapter shall be
reviewed by the City Engineer, or other individual designated by the
City of Monroe, for the following items:
A. Minimum treatment volume standard. The minimum treatment volume standard
shall be one inch of rainfall from the entire site. Treatment methods
shall be designed on a site-specific basis to achieve either a minimum
of 80% removal of total suspended solids (TSS) as compared with uncontrolled
runoff or the limitation of discharge concentrations of TSS to no
more than 80 milligrams per liter. A minimum treatment volume standard
is not required where site conditions are such that TSS concentrations
in stormwater discharges will not exceed 80 milligrams per liter.
B. Channel protection criteria. The channel protection criteria shall
be established to maintain post-development site runoff volume and
peak flow rate at or below existing levels for all storms up to the
two-year, twenty-four-hour event. "Existing levels" shall mean the
runoff volume and peak flow rate of the last land use prior to the
planned new development or redevelopment. Evaluation of this standard
shall be made by the applicant and reviewed by the City Engineer.
C. Establishment of long-term operation and maintenance program. All
structural and vegetative best management practices (BMPs) installed
to meet the requirements of this chapter shall include a plan for
maintaining maximum design performance through long-term operation
and maintenance as a part of the application submittal. Where appropriate
and necessary, the City of Monroe may require an easement for ongoing
access to the facility, may require the facility itself to become
a part of the public storm sewer system, or other requirements may
be imposed as deemed necessary on a case-by-case basis. The City of
Monroe shall retain all remedies available to it through other sections
of the Code of the City of Monroe to address failure of the property
owner to maintain all required BMPs, such as vegetated swales, sedimentation
structures and the like, as a public nuisance, blight or other appropriate
enforcement mechanism. Costs required for compliance shall be billed
as a lien against the property as appropriate.