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    NC Minimum Design Criteria (MDC) for Stormwater Control Measures

    Our team recently attended the North Carolina State University Wet Pond and Wetland Design Update in RTP.  As presented by university and state government employees, the course structured these design strategies within the framework of the recent drafts of Minimum Design Criteria (MDC) Rules for SCMs.  As it stands, MDC rules are a voluntary alternative to the BMP Manual for permits from the state.  Currently, local governments may adopt the MDC in their jurisdictions.  In November the MDC revised draft is scheduled to be codified into rules and supplemented by a stormwater technical guidance manual. For post-construction stormwater management these criteria present a distinct opportunity for regulatory agencies to proactively and efficiently enforce and maintain the quality of SCMs within their jurisdictional boundaries.

    It is well known that permitting, design, and installation of stormwater facilities is highly regulated.  A tremendous amount of money and resources are allocated to the implementation and construction phase of SCMs.  And appropriately so, as the construction of these SCMs underscores a critical step in protecting the watersheds that we depend on in the face of urban development.  What is equally important is the continued maintenance and inspections of SCMs post construction.  Although regulatory enforcement by governing bodies on post construction SCMs maintenance is improving, there is a long way to go before compliance is the norm.

    The “MDC FOR ALL STORMWATER CONTROL MEASURES” broadly provides for improvements to the post construction SCM.  These post construction rules include: clean out after construction, maintenance access, easements, single family residential lots, operation and maintenance (O&M) agreement, and O&M plan (see link at bottom).  Of specific importance is the inclusion of the O&M agreement and plan in the permitting process.

    The O&M agreement requires the property owner to maintain, repair, or reconstruct the SCMs in accordance with the approved design plans and runs with the chain of title of all future owners.  The O&M Plan provides owners and regulators with the specific operation and maintenance work necessary for the proper function of all SCM components on the property.  In a perfect world these binding documents would lend to full compliance by owners and operators and well maintained SCMs.  However, judging from experience in the post construction stormwater industry, once a certificate of occupancy is issued the new owners rarely comply with the O&M agreements.  In many instances this failure to comply occurs because regulators are often not applying any pressure.  The application of MDC for post construction SCMs provides guidance to change this trend.

    Heightened concern for SCMs post construction by governing bodies and property owners may be aided by annual inspection programs and routine maintenance.  It is important to provide minimum frequency requirements (e.g. monthly, quarterly, annually) for the maintenance and inspection of all SCMs.  Specific frequency minimums are important to promote proper function, as well as aid in budgeting, planning, and ensuring compliance.  As a property owner, wouldn’t you want to know exactly how often to service and inspect your SCM?

    More information about the MDC can be found here.  If you have questions or would like to provide comments on the MDC, please see the attached link for contact information.