TCMA Chloride TMDL - Implementation Strategy Summary Revision as of 22:07, 18 May 2016 by PLeegar (talk | contribs)(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff) TCMA Chloride TMDL - Implementation Strategy Summary

Implementation Strategy Summary

Implementation strategies to restore the TCMA waters impaired by chloride are presented in the Implementation Strategy to meet the TCMA Chloride TMDLs chart below and discussed further in this section. Additional information is included in of the TCMA CMP Watershed and Waterbody Characterization section. 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. The of the TCMA CMP Watershed and Waterbody Characterization section 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.

MS4 and Roads=

Chloride management is a challenging issue in Minnesota and requires a balance between public safety and the environment. In addition to the balance, chloride management is complex since every winter event is different. The different events can be a result of the type of precipitation, temperature, longevity of the event, timing of the event, etc. In addition to variations in each event, winter seasons can be highly variable from year to year. Snow and ice maintenance practices vary between road authorities and private applicators. Training, equipment, available resources, and political pressure all factor into the amount of deicer being applied.

There is no single BMP that can cost effectively remove snow and ice and maintain an appropriate level of service for all of the various situations across the TCMA. Chloride management can only be achieved through implementation of an array of different BMPs. The BMPs vary by effectiveness in reducing chloride application and cost of implementing the BMP.

The CMP includes an arsenal of BMPs, which give chloride applicators multiple ways in which to reduce chloride. This provides the BMPs that can be used by high-use/high-experience entities all the way down to low-use/low-experience entities. A wide range of BMPs also allows greater flexibility in the timing and extent of implementation of the BMPs.

Traditional BMP strategies can be implemented by chloride applicators. The primary recommended strategies include, but are not limited to:

1. Shift from granular to more liquid products and higher liquid to solid ratio blends
2. Improved physical snow and ice removal
3. Snow and ice pavement bond prevention
4. Training for maintenance professionals
5. Education for the public and elected officials

This strategy consists of the continued use of chloride containing products in the most efficient and effective manner possible. This approach assumes we maintain the same level of service.

There are several industry shifts that are needed to reduce salt waste. These changes are applicable to all winter maintenance areas in which a high level of service is expected: roads, parking lots, and sidewalks.

Winter Maintenance Assessment tool

A tool called the WMAt has been developed by the MPCA and is available for use by all winter maintenance professionals. The WMAt is a voluntary tool that can be used to understand current practices, identify areas of improvement, and track progress.While optional, everyone that is involved in winter maintenance is highly encouraged to use the WMAt. The tool is intended to streamline and simplify implementation goals and strategies. The tool can also be a great way to compare practices with other entities and learn from each other in order to achieve the greatest chloride reductions while providing a high level of service. Utilization of this planning tool will allow the user to track their progress over time and show the results of their efforts. The tool can serve as both a reporting mechanism to understand the current practices and as a planning tool to understand future practices. The planning side of the tool will help understand the challenges and costs associated with improved practices.

The WMAt provides a more detailed and comprehensive evaluation of all the BMPs available to winter maintenance professionals. More details about the WMAt can be found in Appendix B of the TCMA CMP.

Examples of salt saving BMPs for winter maintenance programs

While the preferred and most effective approach for developing a chloride reduction plan for individual winter maintenance programs is to utilize the WMAt, here are a few BMPs that have been proven to reduce salt use.

1. Calibrate all equipment regularly (both liquid and granular systems)
2. Integrate liquids (avoid applying dry material)
3. Develop a Winter Maintenance Policy/Plan and share it with supervisors, crew and customers
4. Provide state of the art winter maintenance training, education, and professional development for all who work in the industry
5. Store salt indoors and on an impermeable pad
6. Anti-ice before events to reduce bonding of snow to pavement
7. Use ground speed controllers
8. Upgrade to equipment that can deliver low application rates
9. Select products that will work well given the pavement temperatures and conditions
10. Select application rates based on road temperatures and trends, the product used, cycle time, and other factors
11. Start mechanical removal as soon as possible, and continue throughout the storm
12. Use a variety of methods to reduce bounce and scatter of salt
    1. Reduce speed
    2. Higher liquid to granular ration
    3. Lower spinner elevation
    4. Chutes or skirts
    5. Reduced spinner speed or turn off
    6. Target crown of the road or near the center
13. Refine application rate charts and continually test lower rates

These BMPs may not be practical for all winter maintenance programs and should not be considered the best or only options for salt reducing activities, but rather a list of BMPs that many programs have already begun implementing and are seeing reduced salt use as a result. To determine the activities appropriate for each organization please visit the MPCA’s Stormwater Manual to utilize the WMAt.

MS4 permit implications, strategies, and reporting

One of the challenges for public road authorities is the variability in road types, conditions, and meeting driver expectations. Each municipality is faced with unique challenges and circumstances that will play a role in determining the specific BMPs implemented. Development of winter maintenance policies/plans that are proactive and aim to minimize salt use is a critical first step for all winter maintenance programs to begin implementing BMPs in an effective and strategic way. Training and regular professional development for all applicators is another key strategy to allow winter maintenance programs to reduce overall chloride use while providing an appropriate level of service.

Municipalities in the TCMA make up the most significant portion of salt applicators and would be expected to take on the majority of the BMP activities for reducing chloride. Those municipalities with an NPDES Permit in a chloride impaired watershed will be required to report progress on the implementation of salt reducing BMPs beginning after issuance of the next Phase II MS4 Permit, which is expected to occur in 2018. The Phase I MS4s, (St. Paul and Minneapolis) will report their progress in 2016.

The WMAt will be a valuable resource to MS4s in terms of prioritizing and implementing BMPs. Use of the WMAt is not a requirement but will allow each MS4 to determine their own priorities that may be based on cost, location, ease of acceptance or other important factors unique to that MS4s particular situation. The WMAt provides specific BMPs related to all areas of winter maintenance to aid in the development in a detailed plan that meets the unique conditions of each individual program and can be prioritized and implemented according to specific needs and constraints.

The WMAt or other methods of tracking can be used to determine the baseline in terms of current practices and BMP’s that are being implemented. The baseline of practices will allow the MS4 permittees to establish goals and track progress.

Another valuable resource for public road authorities is their peers. Several public road authorities have improved practices, reduced chloride use, and have realized cost savings by implementing the BMPs. These success stories, when shared between entities can demonstrate specifically how chloride reductions have been successfully achieved. Case studies describing some of these local success stories and specific areas of improvement are discussed in Section 3.5 of the CMP.

The MS4 reporting will consist of a discussion of the BMPs that have already been implemented and the BMPs that are planned to be implemented, including a timeline for implementation. Further information on reporting requirements can be found on the MPCA MS4 program website.

Wastewater (and Water Softening Activities)

Wastewater dischargers determined to have a reasonable potential to exceed 230 mg/L, will work with the MPCA to include appropriate permit conditions, including compliance schedules, chloride management plans, and effluent limits. If a permitted facility receives a chloride limit they will be required to submit a CMP to identify sources of chloride.

Municipal Wastewater

For municipal wastewater facilities, technologies capable of removing chloride from wastewater are either cost-prohibitive, technologically infeasible, or a mix of the two. Reverse Osmosis (RO) and evaporation of the resulting brine is the most viable option for removal of chloride from wastewater in Minnesota at the WWTPs. The MPCA analyzed the cost and implementation concerns of using the RO treatment and evaporation to remove chloride for WWTPs in 2012 (Henningsgaard 2012). Based on the assessment, the RO treatment and evaporation are cost prohibitive and pose significant implementation concerns.

The most feasible option for reducing chloride loading to the WWTPs is upstream source reduction. The two primary sources of chloride to WWTPs are residential water softeners and industrial users. If a facility has a chloride limit or wants to voluntarily reduce chloride WWTPs should work through their Industrial Pretreatment Programs (IPP) to identify significant users who may be contributing chloride. The WWTPs can review existing data from industrial users or can require industrial users to collect chloride data to assist in the assessment. If industrial users are identified as a significant source of chloride, the WWTP can work with the industrial user through the IPP to develop and implement a plan to reduce chloride loads.

During the permit issuance or reissuance process, wastewater discharges will be evaluated for the potential to cause or contribute to violations of chloride water quality standards.Water Quality Based Effluent Limits (WQBELs) will be developed for facilities whose discharges are found to have a reasonable potential to cause or contribute to excursions above the water quality standards. The WQBELs will be calculated based on low flow conditions, may vary slightly from the TMDL WLAs and will include concentration based effluent limitations.

Water Softeners

An assessment of the contribution from residential water softener use will also be important for a WWTP. Where residential water softeners are identified as significant sources of chloride, it is recommended that the WWTP develop and implement a plan to reduce chloride at the source. One option for municipalities includes the potential of providing lime or membrane water softening at the WTP in order to eliminate water softening at individual residences. Centralized lime softening eliminates the use of chloride to soften the water and therefore significantly reduces the chloride loading to the WWTP. This option assumes that all the WWTP users would be connected to city drinking water and would have taken their water softener offline. Water softening at the WTP has the potential to be more cost efficient than individual residential water softening for many users. Another, but less effective, approach to reducing salt from residential water softeners is to prohibit the installation of timed water softeners for new construction and provide rebates and/or grants to homeowners that replace existing water softeners with high efficiency ion exchange softeners that use salt more efficiently. The following steps will help to reduce the amount of salt being discharged to a WWTP:

• Know the hardness level of local water supply.
• Consider whether a water softener is even needed and avoid the ongoing expenses if it isn’t needed. Get a water test for hardness. Typically water hardness greater than 120 mg/L CaCO3 needs to be softened. See the University of Kentucky’s Guidance: Hard Water- To Soften Do not over soften. Program the water softener to obtain an optimal level of hardness.
• Uninstall an old timed softener and replace it with a new demand softener. A new demand softener could be optimized to minimize backwashing and the newer model would have a more efficient ion exchange resin.
• If using a timer-based softener, set to recharge at the lowest effective rate and turn it off when on vacation.
• Install a bypass so landscape irrigation water is not softened.
• Consider alternatives to salt-based water softeners.

For homeowners with water softeners who have an on-site septic system, the above steps should also be taken. Chlorides in on-site septic systems will infiltrate to groundwater and may result in elevated levels of chloride in groundwater which can impact water supplies as well as groundwater recharge of lakes, streams, and wetlands.

Industrial Wastewater

For direct dischargers of industrial wastewater, the individual permittee will need to work with the MPCA to develop and implement a plan to reduce chloride if effluent concentrations have reasonable potential to exceed 230 mg/L. Each industrial discharger will have unique circumstances and will need to consider whether source reduction, treatment, or another approach would be most effective in their specific situation.

During the permit issuance or reissuance process, wastewater discharges will be evaluated for the potential cause or contribution to violations of chloride water quality standards. The WQBELs will be developed for facilities whose discharges are found to have a reasonable potential to cause or contribute to excursions above the water quality standards. The WQBELs will be calculated based on low flow conditions, may vary slightly from the TMDL WLAs and will include concentration based effluent limitations.

Non-Permitted Sources

Section 3, Prioritizing and Implementing Restoration and Protection of the CMP, has detailed recommendations for implementation strategies for a wide array of audiences. The motivation for voluntary actions to reduce salt use by non-permitted may include cost savings, protection of surface and groundwater, incentives and community expectations. It is anticipated that efforts to reduce salt use will be conducted across the TCMA at various levels regardless of the motivation.

Agriculture

The primary sources of chloride from agricultural lands in the TCMA are from fertilizers and land application of food processing waste and biosolids from municipal sewage treatment. Excessive chloride concentrations on agricultural lands can be harmful to crop growth in addition to contributing to elevated levels of chloride in surface runoff and groundwater infiltration. While fertilizer is not expected to be source of chloride that is contributing to impairments, implementation of nutrient management

Dust Suppressants

Chloride based dust suppressants are often used for dust control on gravel surfaces. Although little information is available on application rates and how often it is used, it is not expected to be a significant source of chloride in the TCMA. Non-chloride dust suppressants are available and may be an option for reducing chloride in watersheds of concern.

Private Applicators (Commercial, Industrial, and Residential Deicing)

A major challenge in the overall reduction of chloride use in the TCMA is in getting private applicators to reduce chloride usage. There are four primary hurdles related to this effort:

1. Liability concerns for applicators and property owners
2. Education and training for applicators, including cost
3. Contracting practices and incentives for applicators
4. Diversity in personnel experience

Two potential approaches to educating/training private applicators include a required training approach and a voluntary training approach, both discussed further below. A required training assumes that an ordinance or other regulatory mechanism is adopted by a governing body that requires training. A voluntary approach assumes that there is no ordinance or regulatory mechanism in place.

Potential Required Training Approaches:

• Development of a state-wide Smart Salting certification program
• Watersheds to require the MPCA Smart Salting certification for anyone performing professional level winter maintenance in the watershed
• Cities within those watersheds create an ordinance requiring Smart Salting certification to work in their cities
• Cities ask commercial property owners in their city to become trained, or they award contracts only to certified applicators
• All government organizations (state/counties/parks/schools/cities) to hire only Smart Salting certified contractors to maintain government properties
• The MPCA, WDs and WMOs, and cities all help advertise the classes

Potential Voluntary Training Approaches:

• The MPCA to continue offering Smart Salting training
  • Increase the number of classes
  • Expand locations of classes
  • Incorporate alternative methods for certification (e.g.,Webinars)
  • Increase advertising about the availability and importance of being “certified” winter maintenance professionals
  • Watershed organizations, and cities host and advertise classes in their area

In addition to education, a statute that limits liability for private applicators that are certified under the Smart Salting training program would enable private applicators to use less without fear of litigation. An important aspect to a statute like this is requiring certification in order to maintain an appropriate level of service. The State of New Hampshire passed a new law, RSA 489-C, effective November 1, 2013, which limits the liability of business owners who contract for snowplowing and deicing as long as the applicator is certified through the University of New Hampshire – Green SnowPro Program. The entire law can be found at: http://www.gencourt.state.nh.us/rsa/html/NHTOC/NHTOC-L-489-C.htm

Feedback from stakeholders in Minnesota has indicated that many of the private applicators over-apply salt as a result of concerns about litigation. A law similar to New Hampshire’s RSA 489-C could change salt application behaviors of private applicators by limiting their liability.

In some cases, compensation for winter maintenance is based on the amount of salt used, which can incentivize over-application of salt. In this case, the state should develop a boiler plate, performance based contract for private entities to use when contracting for winter maintenance services. Performance based contracting methods and the boiler plate contract should be part of the education, training, and certification programs for private applicators.

Homeowners and Small Business Owners

A clear message on why reducing chloride is important for the environment, important for saving money, and how to effectively apply chloride will be the key to changing salt application behaviors by homeowners and small businesses. This messaging should be carried out by various state and local governmental entities in order to reach a broad range of people in the TCMA.

Nine Mile Creek Watershed District approached this by providing a measuring cup type salt scooper to homeowners and small businesses in order to raise awareness of the amount of salt they are using.

For homeowners with water softeners who have an on-site septic system, the steps described above in Section 8.2.4 should also be taken. Chlorides in on-site septic systems will infiltrate to groundwater and may result in elevated levels of chloride in groundwater which can impact water supplies as well as groundwater recharge of lakes, streams and wetlands.

See the TCMA Chloride TMDL - Watershed and Waterbody Characterization section of the TCMA CMP for more information on implementation strategies.

Cost

The assessment of costs and economic benefits associated with chloride uses and its impacts are complex. However, one thing is certain; removing chloride from impaired lakes and streams is impractical and cost-prohibitive. Therefore, prevention or source control is the logical approach. The various economic impacts and benefits are shown in the Cost Considerations Related to Winter Maintenance Salt Use chart and discussed briefly below.

Implementation of improved winter maintenance activities will come with an initial investment cost to address training, new equipment, and public outreach. However, as a result of reduced salt usage, a cost savings is expected based on information provided by several local winter maintenance organizations. A net cost-savings has been shown by many organizations who have tracked cost before and after the implementation of the winter maintenance BMPs. Table 9 provides examples of tracked cost savings associated with the implementation of various salt reducing BMPs by local winter maintenance organizations. Detailed descriptions of these cost savings examples can be found in the TCMA Chloride TMDL - Watershed and Waterbody Characterization section of the CMP. The cost estimates provided in the Examples of Municipal and Private Cost Savings table reflect implementation of a variety of BMPs with multiple activities applied simultaneously. The information provided in the Examples of Municipal and Private Cost Savings table is not intended to be a reflection of cost for any one practice but rather an overall estimate. Each organization will implement practices that are most appropriate for their individual operations and there is not a one-size-fits-all approach when it comes to winter maintenance; therefore, the costs will vary greatly across organizations. The cost of meeting permit requirements such as reporting will likely be offset by the overall cost savings realized through more efficient and effective winter maintenance

Examples of Municipal and Private Cost Savings
Link to this table

Entity	Implementation Period	Main Actions Implemented	Salt Reduction	Cost Savings
University of Minnesota, Twin Cities	Start 2006	Began making salt brine and anti-icing and adopted several other salt reduction BMPs.	48%	New equipment cost $10,000 $55,000 scost savings first year
City of Waconia	Start 2010	Switch from 1:1 sand:salt to straight salt & liquid anti-icing; calibration; equipment changes; use of air and pavement temperatures.	Switch from 1:1 sand:salt to straight salt & liquid anti-icing; calibration; equipment changes; use of air and pavement temperatures.	$8,600 yearly cost savings ($1.80 per lane-mile)
City of Prior Lake	2003-2010	Upgrade to precision controllers & sanders; anti-icing & pre-wetting; use of ground temperatures, best available weather data; on-site pre-mix liquid & bulk-ingredient storage, mixing & transfer equipment; staff education.	42%	$2,000 per event estimated cost savings; 20 – 40 mg/L decrease in receiving-water chloride (liquid app-only watershed)
City of Richfield	Start 2010	All-staff Training*; yearly sander calibration; use of low-pavement-temp de-icers; road crown-only application; minor-arterial-road policy adjustments	> 50%	$30,000 : 2010-2011 $70,000 : 2011-2012
Rice Creek Watershed District Cities	2012-2013	Staff training; purchased shared anti-icing equipment	32%	$26,400 in one winter
City of Cottage Grove	2011-2012	Staff training	Not available	$40,000 in one winter
City of Shoreview	Start 2006	Stopped using a salt/sand mixture and moved on with straight salt; set up all its large plow trucks with state of the art salt spreading controls, pre-wetting tanks and controls and pavement sensors; use of calcium chloride in the pre-wetting tanks reduced the amount of rock salt as well; all applicators and supervisors annually attend *Training; crews attend an annual snowplow meeting to review procedures and talk about salt use and conservation methods; trucks set up for anti-icing main roads with calcium chloride.	44% since 2006	$24,468 in 2014
City of Eagan	Start 2005	Moved from a 50/50 salt/sand mix to straight salt; eliminated purchase of safety grit; EPOKE winter chemical application technology; use AVL; pre-wet at spinner	Not available	$70,000 annual savings
Joe’s Lawn & Snow, Minneapolis	Start 2013-2014	Owner & staff Training*; purchase of new spreader, temperature sensors; equipment calibration; use of temperature data; on-going experimentation.	50%	$770 estimated cost savings in 2014 - Expected to use 20 tons, only use 9 tons

MPCA Smart Salting Training (All entities described above have attending the MPCA Smart Salting Training.)

Application of salt is a common method of maintaining safe roads, parking lots, and sidewalks. The economic benefit of safe travel, for both vehicles and pedestrians, is hard to measure. Economic benefits also come in the form of reduced work loss time.

The economic impacts from salt use goes beyond the impairment of lakes and streams and includes costs associated with damage to transportation infrastructure, vehicle corrosion, and vegetation damage.

Removal of chloride from the end-of-pipe of municipal wastewater treatment facilities is cost prohibitive. Source reduction is a critical element of discussions related to wastewater treatment of chloride-containing waste streams.

Cost considerations related to winter maintenance salt use.

Reductions in chloride loads from winter maintenance activities will result from improved practices. The improved practices are intended to maintain a consistent level of service in terms of safe roads, parking lots, and sidewalks at a lower level of salt use. While improving practices may require an initial investment, long-term cost-savings have been realized as a result of reduced salt purchases. As part of the TCMA CMP project, an Economic Analysis of Road Salt in the TCMA was completed (Fortin Consulting, 2014). This analysis included examples of salt reductions achieved with the associated cost savings. The specific examples of the unique opportunity for overall cost savings associated with implementing the BMPs that reduce salt use can be found in the [http://stormwater.pca.state.mn.us/index.php/TCMA_Chloride_TMDL_-_Watershed_and_Waterbody_Characterization TCMA Chloride TMDL - Watershed and Waterbody Characterization section of the CMP.

Municipal Wastewater (primarily from Water Softening)

The cost for wastewater source dischargers to remove chloride from their waste stream is very high and will likely be cost prohibitive for most facilities. Below are estimates of the cost to treat effluent from a WWTP, which were developed by Henningsgaard, 2012:

An estimate for the total cost is $4-$5.25 million:

• Fine filtration - $1.5 million per million gallons treated
• RO - $1-$2.25 million per million gallons treated
• Evaporation technology prior to landfill – $1.5 million per million gallons treated

Annualized cost for construction (assuming a 20 year term at a market rate of 2.25%) – between $250,568 and $328,871 per year.

Annual Operation and Maintenance costs:

• Fine filtration – $0.01 to $0.15 per 1,000 gallons treatment
• RO - $2,200 per million gallons treatment
• Evaporator fuel - $10,000 to $12,000 per month

Based on specifics from each community, this cost could be considered to have “substantial and widespread economic and social impact” (40 CFR 131.10 (g) (6)) and could be justification for a variance that would not require this type of expensive treatment. The waste stream from the RO treatment at the WWTPs has the potential to produce highly concentrated brine with (environmentally and economically) challenging disposal characteristics.

Due to the high cost of end-of-pipe treatment for chloride and the high cost and difficulty of final disposal of the brine, source reduction is a critical element of discussions related to wastewater treatment of chloride-containing waste streams.