1. MS4 = Municipal Separated Storm Sewer System
By James E. Amundsen, P.E.

2. Why Should You Care?
MOA & DOT&PF are joint Permittees, permit:
Permit effective 2/1/2010 to 1/31/2015
EPA Consent Decree??
Personal Liability - Subject to criminal penalties of $2,500 to $25,000 per day of violation, Or imprisonment of not more than one year, or both.

3. What is an MS4?
An MS4 is a conveyance or system of conveyances that is:
Owned by a state, city, town, village, or other public entity that discharges to waters of the U.S.;
Designed or used to collect or convey stormwater (including storm drains, pipes, ditches, etc.);
Not a combined sewer; and
Not part of a Publicly Owned Treatment Works (sewage treatment plant).

4. Overview
Polluted stormwater runoff is commonly transported through Municipal Separate Storm Sewer Systems (MS4s), from which it is often discharged untreated into local water bodies. To prevent harmful pollutants from being washed or dumped into an MS4, operators must obtain a NPDES permit and develop a stormwater management program.
Phase I, issued in 1990, requires medium and large cities or certain counties with populations of 100,000 or more to obtain NPDES permit coverage for their stormwater discharges. There are approximately 750 Phase I MS4s.
Phase II, issued in 1999, requires regulated small MS4s in urbanized areas, as well as small MS4s outside the urbanized areas that are designated by the permitting authority, to obtain NPDES permit coverage for their stormwater discharges. There are approximately 6,700 Phase II MS4s.
Generally, Phase I MS4s are covered by individual permits and Phase II MS4s are covered by a general permit. Each regulated MS4 is required to develop and implement a stormwater management program (SWMP) to reduce the contamination of stormwater runoff and prohibit illicit discharges.

5. MS4 Requirements
Pursuant to Rule 13, each MS4, is required to develop a Storm Water Quality Management Plan (SWQMP) which is basically an action plan for the MS4 entity to institute six requirements, or minimum control measures (MCM):
Public Education and Outreach
Public Involvement and Participation
Illicit Discharge Detection and Elimination
Construction Site Storm Water Runoff Control
Post-Construction Storm Water Management in New Development and Redevelopment
Pollution Prevention/Good Housekeeping for Municipal Operations Maintenance

6. Permit Compliance Topics
Requirement:
Many Requirements very similar to Construct General Permit (Because Construction Site Runoff Control is also part of the overall MS4 permit)
Permenant BMP’s that address the ‘post-construction’ storm water management

7. Permit Compliance Topics
Specific Requirements:
Applies to all areas of New Development & Redevelopment
Runoff generated from first 0.52 inches/24 hr event of rainfall
Retention vs detention

8. Runoff Volume Reduction
Canopy interception
Soil amendments
Evapotranspiration
Rainfall harvesting
Engineered Infiltration
Extended Filtration

9. Storm Water Design Criteria
Manual Update Coming – Compliance Challenges until it is Updated
Green Infrastructure/LID Strategies – use them!
Document your efforts in your DSR

10. Plan Review & Approval DOT&PF Reviews DOT&PF Plans
MOA reviews MOA & Developer Plans
Expect Review comments to cover both temporary (BMP’s in ESCP) and permanent practices your design includes
DSR’s should include specific discussion of both construction BMP’s as well as permanent management measures

11. Helpful Links Here’s a link for on-line MS4 training.
EPA Website:
Anchorage website:
Copy of current Permit – with presentation
2012 Report Joint Report

12. Questions?