Planning

The Integrated Planning and Design Focus Areas section presents an integrated approach for meeting the stormwater runoff quality and quantity management goals by addressing the key adverse impacts of development on stormwater runoff. The purpose is to provide guidance for designing a comprehensive stormwater management system.

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Water Quality

Hydrologic studies show smaller, frequently occurring storms account for the majority of rainfall events. Consequently, the runoff from the many smaller storms also accounts for a major portion of the annual pollutant loadings. By treating these frequently occurring, smaller rainfall events and the initial portion of the stormwater runoff from larger events, it is possible to effectively mitigate the water quality impacts from a developed area.

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Hydrology

Hydrology deals with estimating flow peaks, volumes, and time distributions of stormwater runoff. The analysis of these parameters is fundamental to the design of stormwater management facilities, such as storm drainage systems and structural stormwater controls. In the hydrologic analysis of a development/redevelopment site, there are a number of variable factors that affect the nature of stormwater runoff from the site.

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Hydraulics

Stormwater system design is an integral component of both site and overall stormwater management design. Good drainage design must strive to maintain compatibility and minimize interference with existing drainage patterns; control flooding of property, structures, and roadways for design flood events; and minimize potential environmental impacts on stormwater runoff.

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Site Development Controls

Structural stormwater controls are engineered facilities intended to treat stormwater runoff and/or mitigate the effects of increased stormwater runoff peak rate, volume, and velocity due to urbanization. This section provides an overview of structural stormwater controls that can be used to address the minimum stormwater management standards.
*Updated May 2021.

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Construction Controls

In order to address the requirements of pollution reduction at construction sites, a variety of controls should be employed to reduce soil erosion, reduce sediment loss from the site, and manage construction-generated waste and construction related toxic materials. Controls consist of both temporary and permanent methods to reduce pollution from a construction site.

These schematics are being incorporated into the Public Works Construction Standards. Please see the NCTCOG website for more details.

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Landscape

Landscaping is a critical element in the design of stormwater facilities for water quantity and quality management, serving both functional and aesthetic purposes. Plants and vegetation perform a number of functions in stormwater controls and conveyance facilities. The purpose of this section is to provide guidance on landscaping and plant selection for stormwater facilities and structural controls, as well as provide an overview on developing aesthetically-pleasing stormwater facilities.

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Notice of June 2021 Revisions

In June 2021, revisions to the iSWM Technical Manual were made. This document outlines those changes.

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Notice of September 2020 Revisions

In September 2020, revisions to the iSWM Technical Manual were made. This document outlines those changes.

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Notice of September 2014 Revisions

In September 2014, revisions to the iSWM Technical Manual were made. This document outlines those changes.

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Hydrology - Sept. 2014

Hydrology deals with estimating flow peaks, volumes, and time distributions of stormwater runoff. The analysis of these parameters is fundamental to the design of stormwater management facilities, such as storm drainage systems and structural stormwater controls. In the hydrologic analysis of a development/redevelopment site, there are a number of variable factors that affect the nature of stormwater runoff from the site.

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Construction Control Schematics - 2018

Addendum to iSWM Technical Manual - Construction Controls.

A selection of iSWM construction control BMP schematics chosen to be provided in standard details.

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Site Development Controls - 2014

Structural stormwater controls are engineered facilities intended to treat stormwater runoff and/or mitigate the effects of increased stormwater runoff peak rate, volume, and velocity due to urbanization. This section provides an overview of structural stormwater controls that can be used to address the minimum stormwater management standards.

Download 2014 Site Development Controls PDF