Post-Construction Stormwater Management

The post-construction stormwater management program oversees stormwater runoff from new development and redevelopment sites that drain into the Municipal Separate Storm Sewer System (MS4). The City of Monroe’s Stormwater Management Ordinance (SWMO) combines post-construction stormwater management control requirements for all watersheds into one simplified set of stormwater control measures. It also provides a mechanism to require long-term operation and maintenance of Best Management Practices (BMPs) and Stormwater Control Measures (SCMs) and ensures controls are in place to minimize impacts to water quality. Post-construction stormwater management includes a combination of structural SCMs and non-structural BMPs designed to control the runoff from land continuously after construction is complete. Below are some examples of the requirements.

Impervious Surface Requirements:

  • No new impervious or partially impervious area in the floodplain
  • 36% maximum impervious surface density in Critical Area of Water Supply Watershed 
  • 35 feet minimum landward setback for all impervious surface for all perennial and intermittent surface water


For Special Use Permit and Conditional Zoning District

  • 50 feet minimum landward setback for all impervious surface for all perennial and intermittent surface water.


Structural Stormwater Control Measure Requirements:

  • SCMs shall be designed in accordance with the current North Carolina Department of Environmental Quality Stormwater Design Manual
  • Residential development that cumulatively disturbs more than one acre and is not part of a larger common plan of development or sale, and non-residential development that cumulatively disturbs more than one-half acre and is not part of a larger common plan of development or sale are required to control and treat the first inch of runoff.
  • The treatment system shall have an 85% minimum annual removal of Total Suspended Solids (TSS).
  • For all non-residential sites containing new development and/or redevelopment (including road construction, grading, paving, gravel placement, and construction of buildings and other structures) which include the creation of 20,000 square feet or more of new impervious area are required to control the two-year and ten-year post-development peak discharge rates to pre-development peak flow rates.
  • Impervious surfaces in existence prior to the adoption of the SWMO are not included in the computation of impervious area. For exemption and addition requirements, see the City’s SWMO.
     

Maintenance Requirements

Owners of each structural SCM installed shall maintain and operate as to preserve and continue its function in controlling stormwater quality and quantity as initially intended. Owners shall submit an annual inspection report to City of Monroe. Homeowners and other associations shall establish an escrow account for the maintenance of stormwater SCM(s).

Annual SCM Inspection Forms

Bioretention
Cistern
Disconnected Impervious Surface (DIS)
DrainGuard
Dry Pond
Filter Strips with Flow Dispersion
Grassed Channels – Swales
Infiltration Trench
Proprietary Device – Contect
Riparian Buffer
Sand Filter
Underground Detention System
Wet Pond
Wetland

For additional information, please see the “Resources” section on the Stormwater Services page to view the Administrative Manual for Implementation of the SWMO (refer to Chapter 7 about the Operation and Maintenance Agreement), and required checklists.