Stormwater Design Standards Manual

The Revised Stormwater Design Standards Manual is Effective July 1, 2020

The Revised Manual is Available here as a PDF a short summary flyer of major changes to the Manual is available here as a PDF (SWDSM Fact Sheet) 

The prior manual is available here as a PDF (Prior SWDSM)

The City is Providing 4 Technical Education Workshops Regarding the Manual Updates. Technical Memos summarizing details about procedures associated with the Manual will be provided on this webpage with draft versions in advance of each Workshop and final versions posted following the Workshops.

More information about the workshops is on the flyer available here as a PDF (SWDSM Workshops Flyer)

The schedule for workshops is as follows, they will be hosted on Zoom! With Login Information posted to this webpage prior to the meetings.

May 28, 2020 - Workshop #1: 5:30 p.m.—7:30 p.m. “Submittal, Permitting, and Closeout Process”

Watch a recording of the May 28 workshop here

Workshop Agenda

Workshop Presentation

SWDSM Technical Procedure Document #1 – Stormwater Permitting Process

SWDSM Technical Procedure Document #2 – Conceptual Planning

June 4, 2020 - Workshop #2: 5:30 p.m.—7:30 p.m. “Overview of Basin Analysis (‘the 10% Design Rule’) and Peaking Factor”

Watch a recording of the June 4 workshop here

Workshop Presentation

SWDSM Technical Procedure Document #3 – Peaking Factor

SWDSM Technical Procedure Document #4 – 1 Percent AEP Storm Event Analysis

June 11th, 2020 - Workshop #3: 5:30 p.m.—7:30 p.m. "Overview of the Special Protection Area (SPA) Requirements and City Watershed Modeling Data"

Watch a recording of the June 11 workshop here

Workshop Presentation

Workshop Agenda

SWDSM Technical Procedure Document #5 – City Watershed Modeling Data

June 18th, 2020 - Workshop #4: 5:30 p.m.—7:30 p.m. “Overview of Wetland Modeling, Submerged Systems, and Using Low Impact Development (LID) Design Techniques”

Watch a recording of the June 18 workshop here

Workshop Presentation

Workshop Agenda

SWDSM Technical Procedure Document #6 – Wetland Systems Modeling

SWDSM Technical Procedure Document #7 – Equalization Pipes and Submerged Systems

SWDSM Technical Procedure Document #8 – LID and the Coastal SC LID Design Guide

About the Manual

The Stormwater Design Manual standardizes how stormwater elements of a project are designed, submitted, reviewed, approved, and inspected.

Check out the Stormwater Design Standards Manual (PDF).

The following is a link is to the final draft of the updated Stormwater Design Standards Manual that is to be considered by City Council during a workshop on 01/27/2020 at 3pm at City Hall (80 Broad Street). A public comment period will follow the workshop beginning at 4pm that day. Included is a one page fact sheet linked below for your convenience. 

January 2020 Draft Manual

SWDSM Fact Sheet 

History

In September 2007, the City of Charleston passed a more robust stormwater ordinance that incorporates requirements of the federally mandated NPDES Phase II stormwater program. As required, the new ordinance addresses elements of Minimum Control Measures (MCM) number four and five, construction-site stormwater control, and post-construction stormwater control, respectively.

The stormwater ordinance also authorized the development and implementation of a Stormwater Design Standards Manual (SWDSM) for use by the City of Charleston when reviewing, approving, and permitting construction, development, and re-development projects. The SWDSM standardizes engineering and construction practices within the City of Charleston’s jurisdiction. It will serve to:

  • Provide application submission requirements and the approval process
  • Provide technical design standards to address water quantity control
  • Provide technical design standards to eliminate the implementation of sub-optimal design and installation practices
  • Provide general information to improve water quality, prevent illicit discharges, and minimize stormwater runoff impacts
  • Provide other protection provisions related to stormwater discharges

Similarities to Other Standards

The SWDSM developed by the City of Charleston is very similar to the manual developed by Charleston County, and it shares many similarities to SCDOT standards. Where the SWDM differs from other standards, in many cases the City of Charleston found that certain design or installation practices create water quality or maintenance problems and it is attempting to prevent those problems from reoccurring.

Adoption & Updates

The SWDSM was formally adopted by the City Council on January 12, 2010. All new submissions for projects within the City of Charleston should be done in accordance with this manual.

After careful consideration and review of several sections of the manual, it has been updated and approved by the City Council as of February 8, 2011 and most recently February 26, 2013. Any project coming for review for the first time will need to adhere to these standards.

Resources