The Phase II MS4 General Permit regulations authorize discharges of storm water from municipal separate storm sewer systems owned or operated by a public entity, located in an urbanized area. As part of the rule, municipalities are required to employ a program, which reduces the pollutant loadings in storm water runoff, which discharge to receiving waters to the maximum extent practicable (MEP). The main objective of this permit is to implement a Storm Water Management Plan (SWMP) outlining a 5 year plan to reduce the discharge of pollutants from the MS4 to protect water quality and satisfy water quality requirements of the Clean Water Act.
On August 13, 2007, the TCEQ issued the Texas Pollutant Discharge Elimination System (TPDES) TXR040000 Permit, which authorizes the discharge of storm water to surface water of the state from all small municipal separate storm sewer systems (MS4s) located in an urbanized area. According to the permit, an MS4 is defined as:
A conveyance or system of conveyances (including roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, man-made channels or storm drains): (i) owned or operated by the United States, a state, city, town, borough, county, district, associated, or other public body (created by or pursuant to state law) having jurisdiction over disposal of sewage, industrial wastes, storm water, or other wastes, including special districts; (ii) designed or used for collecting or conveying storm water; (iii) which is not a combined sewer; (iv) which is not part of publicly owned treatment works (POTW) as defined by 40CFR122.2; and (v) which was not previously authorized under a NPDES or TPDES individual permit as a medium or large MS4.
The Dallas/Ft. Worth International Airport (DFW Airport) is subject to the TXR040000 regulation because DFW Airport is a public entity, as established under the Texas Transportation Code Chapter 22. Furthermore, DFW Airport is located in an urbanized area between the cities of Dallas and Ft. Worth, and holds jurisdiction over a system designed for collecting and disposing storm water to waters of the U.S.
In order to reduce storm water pollution, the DFW Airport SWMP addresses six minimum control measures (MCMs): Public Education and Outreach, Public Involvement/Participation, Illicit Discharge Detection and Elimination, Pollution Prevention for Municipal Operations, Construction Site Storm Water Runoff Control, and Post Construction Storm Water Management. Sections from the DFW Airport SWMP are provided below: