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MS4 Storm Water Outfall Inventory Advanced Outfall Tracking System (AOTS)

The Advanced Outfall Tracking System (AOTS) is a GIS application with a central database that holds field-collected spatial data associated with mapped outfalls. It is the system TxDOT uses to track compliance with the Texas Pollutant Discharge Elimination System (TPDES) permit requirements related to our Municipal Separate Storm Sewer System (MS4). Currently, the system is only available for use by TxDOT.

The system is used to track:

  • Outfall locations
  • Illicit discharge inspections
  • Follow-up inspection of outfalls
  • Collection of representative storm water samples
  • Physical observation and chemical data screening
  • Outfall location classifications

Additional functions include the display of:

  • Spatial locations of outfall points
  • Images associated with each outfall
  • Map tips
  • Reports

Dry weather screening points are chosen based on the tracking system as well as discharge areas and routes.

MS4 Outfall Map and Reporting

Using AOTS, TxDOT compiles reports and a storm sewer outfall map that contains the elements required under MS4 permits. The AOTS stores data associated with field inspections, follow-up investigations, and third-party/off-site information. The stored data can be accessed via internal storage system and additionally through a Bing maps web application with links to storm water survey databases.

The website provides dynamic mapping capabilities and near real-time tracking of information related to Agency outfalls within individual districts and across the entire state of Texas.

Illicit Discharge Detection and Elimination (IDDE) Program

The AOTS is designed to detect and report illicit discharges that occur within TxDOT's MS4 permitted areas. The Outfall Field Inspection Work Flow Diagram and Classification Scheme are also utilized during field inspection. This graph is designed to assist the user in determining if the inspected outfall should be considered non-illicit discharge/outfall or illicit discharge/outfall.

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