Section 6: Storm Water Management

Introduction

Maintenance of the highway system should be performed not only with the goals of safety and efficiency but also in an environmentally sensitive manner. One of the most important environmental issues confronting the department is water quality. Although the impacts of runoff pollution on receiving waters from our facilities may not be significant, it is generally recognized that responsible agencies may be required by federal and state regulations to apply the best management practices available to reduce pollutant loads entering water bodies.

Policy

The department should use best management practices when contracting for or performing maintenance on the state's highways and rights-of-way. Although the publication "Storm Water Management Guidelines for Construction Activities" was developed for construction, it is a good guide and has measures that can be used directly for maintenance activities. One of the basic principles is to ensure proper use, storage and disposal of materials to minimize and/or prevent storm water pollution. The development and implementation of best management practices minimize runoff of contaminants from pavements and bridges.

Texas Pollutant Discharge Elimination System (TPDES) - Construction General Permit (CGP) (TXR150000)

This permit was issued as part of the Texas Pollution Discharge Elimination System (TPDES), for discharging storm water from construction sites to the surface waters of the state. Although the title of the permit only mentions construction, it also affects maintenance. It allows storm water discharges from state force contract maintenance work sites provided that specific guidelines are followed. Work that disturbs less than one acre is generally excluded from the regulatory requirements. Therefore, unless a work activity is excluded from construction general permit (CGP), it must comply with the CGP's requirements.

CGP Excluded Activities

The following maintenance activities are excluded from requiring compliance with the CGP, regardless of the acreage involved.
  • Work "performed to maintain the original line and grade, hydraulic capacity, and original purpose of a ditch, channel, or other similar storm water conveyance." In other words, ditch and channel cleaning for maintenance reasons.
  • Routine grading of dirt roads, clearing of the rights of way and shoulder blading.
  • Pavement work such as seal coats, overlays, and spot base repair.
While these activities are excluded from the CGP requirements, they may still require a U.S. Army Corps of Engineers 404 permit. In addition, even if an activity is excluded, but it has the potential to produce erosion, always employ best management practices.

Activities Not Excluded from the CGP

Any maintenance activity, not excluded above, should be considered a construction activity. Contact your District Environmental Quality Coordinator for guidance.

CGP - Notices of Intent/Notices of Termination

The procedures for filing Notices of Intent (NOI) and Notices of Termination vary by District. Contact your District Environmental Quality Coordinator (DEQC) for specifics.
When applicable, follow these general guidelines for determining your level of CGP coverage.
  • Projects impacting less than one acre do not require coverage under CGP, but do require appropriate Best Management Practices (BMP).
  • Projects not exempted by the CGP that disturb one or more acres require a Storm Water Pollution Prevention Plan (SW3P) and a Construction Site Notice (CSN) to be posted on the site prior to beginning work.
  • Projects not exempted by the CGP that disturb five or more acres require a Notice of Intent (NOI) to be submitted to TCEQ prior to the commencement of earth disturbing activities. A Notice of Termination (NOT) must be submitted to TCEQ after construction is complete and the site has been re-vegetated to 70 percent of the native background cover.

CGP Summary

In summary, it is necessary to:
  • Preserve the existing vegetation when possible
  • Minimize disturbances
  • Re-vegetate quickly (generally should be initiated within 14 days after activities temporarily or permanently cease on portion of the site)
  • Install sediment controls (e.g. silt fence, rock filter dam) at all down-slope boundaries of the site, and side-slope boundaries when appropriate.