The iSWM Online Technical Manual contains iSWM Technical Guidance documents that will be maintained by NCTCOG on the web. This module is referenced by the iSWM Criteria Manual and provides the technical details to meet the requirements established by each community in their iSWM Manual.

The program is split into 7 categories available for download below.

iSWM Technical Manual Documents


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.

Download PDF

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.

Download PDF


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.

Download PDF


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.

Download PDF

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.

Download PDF

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.

Download PDF

Construction Control Standard Details

Addendum to iSWM Technical Manual - Construction Controls.

A selection of 10 iSWM construction control BMP schematics chosen to be provided in standard details.

Download PDF


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.

Download PDF

Notice of September 2014 Revisions

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

Download PDF