Stormwater Permitting & Design


How does ALDOT
plan for stormwater drainage leaving roadways?

Tasks throughout the roadway design process call for designers to account for expected runoff and work toward ADEM permit coverage.

ALDOT uses numerous stormwater management best management practices (BMPs) to address possible stormwater discharge changes caused by roadway development activity.

ALDOT’s construction stormwater management activities are governed by the “Construction General Permit” issued by ADEM. Below are the current version of the CGP and guidance for determining whether the CGP applies to an ALDOT activity:

Construction General Permit
ALDOT Decision Chart for NPDES Permitting of ALDOT Construction & Maintenance Activities
ADEM Discussion: Construction & Normal/Scheduled Maintenance

The following are assorted tools designers use to select and design stormwater management best management practices (BMPs) for construction sites, develop roadway project plans that include stormwater management measures, and obtain CGP coverage for particular projects:

ALDOT Guide for Developing Construction Plans
ALDOT NPDES Permitting Instructions for Construction
ALDOT Area Stormwater Coordinator List
Erosion & Sediment Control Plan Template (DGN)
ALDOT Special and Standard Highway Drawings (Erosion and Sediment Control)
ALDOT Environmental Project Notes
BMP Sediment Reduction Calculation Spreadsheet
ALDOT Construction Best Management Practices Plan (CBMPP) Template

Note that the “Design Component” of the CBMPP is developed during a project’s design phase. The “Operational Component” is developed throughout the construction phase of a project; see the Construction Stormwater Management page.

ALDOT must manage the possible changes in post-construction runoff flows and volumes, as per ALDOT’s MS4 program. A project involving the construction of at least one new travel lane is likely subject to post-construction stormwater management requirements. Planning to accommodate post-construction measures begins early in the project design phase. Below are materials that provide general orientation to ALDOT’s post-construction stormwater management policy as well as guidance for determining the possible magnitudes and impacts of flow and volume changes for a project:

ALDOT Post-Construction Stormwater Management Overview
GFO 3-73: Post-Development Stormwater Runoff Management
Small Storm Runoff Calculations
Flood Risk Assessment
Pre- vs. Post-Development Spreadsheet
Form HYD-100
Form HYD-101

The selection and design of post-construction BMPs should be done in coordination with the Stormwater Engineer, Nicholas Franklin, P.E at 334.242.6071.

Parties outside of ALDOT (e.g., consultants) can input and track project data using the ALDOT Stormwater Tracking System (SWTS). Use the links below to access SWTS and for guidance on entering project data:

ALDOT Stormwater Tracking System (SWTS)
Entering ALDOT Project Data Using SWTS

Visit the Construction Stormwater Management page to find information related to implementing stormwater management practices on ALDOT construction sites. To learn more about other ALDOT environmental activities, visit ALDOT’s Environmental Information page. For questions pertaining to the Stormwater Permitting & Design Program contact Nicholas Franklin, PE by email at or call 334.242.6071.