TCMA Chloride TMDL - Implementation Strategy Summary

Implementation Strategy Summary

Implementation strategies to restore the TCMA waters impaired by chloride are presented in Figure 10 below and discussed further in this section. Additional information is included in Section 3 of the TCMA CMP. While these strategies apply generally across the TCMA, individual entities, such as the WDs or cities, may want to develop individual plans for specific impaired and high risk waters. Prioritizing reduction activities is a local decision and requires evaluation of local conditions and variables. Section 3.1 of the CMP offers some suggestions.

Implementation Strategy to meet the TCMA Chloride TMDLs

Performance-Based Approach for Achieving TMDLs

Deicing salt is the most common and the preferred method for meeting the public’s winter travel expectations. There is currently no environmentally safe and cost-effective alternative that is effective at melting ice. Therefore, continued use of salt as the predominant deicing agent for public safety in the TCMA can be expected. Setting a specific chloride load reduction target for each individual winter maintenance chloride source is challenging, as is measuring actual chloride loads entering our surface and groundwater from salt and other nonpoint sources in the TCMA. Therefore, priority should be put on improving winter maintenance practices to use only a minimal amount of salt, also referred to as smart salting, across the entire TCMA. With these considerations in mind, the implementation approach for achieving the TMDLs and protecting all waters in the TCMA is to focus on performance of improved winter maintenance practices as well as continuing to monitor trends in local waterbodies. A standard approach to the TMDL implementation is to translate the WLA component of the TMDL directly to a numeric permit limit, which is typical for permitted facilities with monitoring requirements. In the case of urban stormwater regulated through a MS4 Permit, the WLA may be presented in the form of a percent reduction from a baseline condition. The specified percent reduction is then included in the MS4 Permit. With a performance-based approach, the numeric WLA is translated to a performance criterion. This can include the development and implementation of a winter maintenance plan which identifies a desired level of BMP implementation and a schedule for achieving specific implementation activities. Progress made towards those goals are documented and reported, along with annual estimates of salt usage and reductions achieved through the BMPs implemented.

In cases where it is not “feasible” to calculate a numeric effluent limit, federal regulations allow for the use of BMPs as effluent limits (40 CFR § 122.44(k)). Such a performance-based or BMP approach to compliance with the WLAs is being taken by states to address the Chesapeake Bay TMDL for nutrients. The TMDL is being implemented through state Implementation Plans. Some states are taking a performance-based approach to addressing urban stormwater sources, requiring minimum levels of BMP implementation rather than requiring specific levels of pollutant load reductions.

A performance-based approach will be tracked through documentation of existing winter maintenance practices, goals for implementing improved practices including schedules, and reporting on progress made. Entities may choose to use the WMAt, which is a smart salting BMP tracking tool, to assess and document practices and set goals, or another approach of their choice. More information about the WMAt can be found in Appendix B of the TCMA Chloride Management Plan. Entities should track progress and document efforts, including, to the extent possible, estimates of reduced salt usage as a result of improved practices. Entities that have achieved their goals for winter maintenance will have documented their practices in a winter maintenance plan. This plan should be reviewed annually and evaluated against the latest knowledge and technologies available for winter maintenance.

The performance-based approach does not focus on specific numbers to meet, but rather on making progress with BMPs. Progress is measured by degree of implementation and trends in ambient monitoring. In a traditional approach with numeric targets, progress would be measured by accounting for salt applied and comparing to the targets. The performance-based approach is intended to allow for flexibility in implementation and recognize the complexities involved with winter maintenance. Because the performance-based approach doesn’t provide a specific numeric target, a limitation of the approach is that it is not definitive on when enough progress has been made. This can only be determined by continued ambient monitoring that demonstrates compliance with water quality standards.