MWRA Local Limits Proposed Revisions

Proposed Revisions to the
Massachusetts Water Resources Authority's
Local Discharge Limits

CONTACT: Denise Breiteneicher | Phone: 617-788-2328 | denise.breiteneicher@mwra.state.ma.us

Back to: What's New in TRAC

May 1, 2002

TABLE OF CONTENTS

I. Background

II. Study Summary

III. Discussion of Key Changes to the Limits

IV. Summary of Analysis Results

I. BACKGROUND

The requirement that MWRA conduct a periodic analysis of the discharge limits applicable to local industrial dischargers is in the EPA Pretreatment Regulations, 40 CFR Part 403, and is also included in the MWRA’s NPDES Permits. Under this requirement, MWRA must review the adequacy of existing discharge limits and establish additional standards, if necessary, to prevent pollutants from entering the treatment system that would interfere with the operation of the treatment plant, degrade the quality of biosolids, or pass untreated through the treatment plant to contaminate the receiving water.

This review involves an evaluation of the performance of the treatment plant, the NPDES Permit requirements, the characteristics of the receiving water, and worker health and safety. This analysis is required approximately every five years. TRAC has worked diligently to ensure that data used in the analysis is accurate and relevant and to ensure that the analysis will meet the MWRA’s overall needs.

Conducting a periodic review of the local limits enables MWRA to establish standards and control measures that reflect the particular characteristics of our system, including:

Type and amount of industrial discharge
Existing quality of receiving water
Sludge quality
Pollutant loadings from sources other than permitted industries
Treatment plant performance

The most significant change in the wastewater system since the last local limits analysis was performed in 1991-1992 has been the construction of the new Deer Island Wastewater Treatment Plant. Particularly with the provision of secondary treatment, pollution removal rates at the Deer Island Treatment Plant have changed dramatically. Under current conditions, the federal and state limits on metals in the fertilizer pellets intended for beneficial re-use are the most important factors that drive the setting of local limits on industrial dischargers.

The local limits analysis indicates that most of the existing local limits are not a candidate for revisions; these limits adequately protect the treatment system and are not unreasonably burdensome on the regulated community. There are, however, fifteen parameters for which changes are proposed.

The tables below list the recommended changes. Table 1 outlines the limits that will require a more stringent limit, Table 2 lists the limits that may be relaxed or eliminated, and Table 3 lists the limits that are being replaced by other limits. More detail is provided in Attachment A. A summary of the background information for all parameters that are being analyzed as part of the local limits study is outlined in Attachment B.

Table 1 Substances for Which Limits are Proposed to Become More Stringent

Substance	Existing Limit (mg/l)	Proposed Action	Justification
Benzene	1.0 (TTO)	Lower to 0.3 mg/l	Concern about toxicity of fumes in sewer lines
Copper	1.5	Lower to 1.0 mg/l	Part of comprehensive strategy to reduce overall copper loadings
Fluoranthene	1.5	Lower to 1.0 mg/l (put on TTO list)	Should be treated like other TTOs
Hexachlorobutadiene	3.0	Prohibit	Concern about toxicity of fumes in sewer lines
Pentachlorophenol	.05	Prohibit	This is a pesticide and therefore it is being reclassified and placed on the prohibited list of pesticides.
Vinyl chloride	1.0 (TTO)	Lower to 0.02 mg/l	Concern about toxicity of fumes in sewer lines
Vinylidene chloride	1.0 (TTO)	Lower to 0.3 mg/l	Concern about toxicity of fumes in sewer lines
Dichlorodifluoromethane	None	Set at 1.0 mg/l and put on TTO List	Concern about toxicity of fumes in sewer lines

Table 2 Limits Proposed for Increases or Elimination

Pollutant	Existing Limit (mg/l)	Proposed Action	Justification
Acrolein	Prohibited	Raise to 0.15 mg/l	Acrolein may be used as a pesticide and therefore, it has always been included in the blanket prohibition on pesticides in the Sewer Use Regulations. However, its primary use in the MWRA Sewer Service Area is not as a pesticide, and so, the MWRA would prefer to enforce a specific limit based on associated water quality and worker safety risks. The fume toxicity analysis showed that collection system workers should be protected if acrolein were discharged at levels at or below 0.15 mg/l.
Boron	20.0	Eliminate boron limit	The boron loadings to the system are significantly below the allowable loadings and have not been detected in the pellets since 1998. There are no indications that there will be a significant increase in boron discharges in the future. Therefore, there is no technical justification for a boron limit at this time.
Chlorinated Naphthalenes	0.8	Move to TTO list – revised limit will be 1.0 mg/l	There is no technical basis for a lower limit than the other organics on TTO list.
Formaldehyde	1.0 (TTO)	Raise to 9.0 mg/l	Formaldehyde is a fume toxicity issue. Based on industry’s comments, the limit was revised to 9.0 mg/l. This limit is based on the undiluted ACGIH short-term exposure level.
pH*	5.5-10.5 standard units	Raise upper limit to 12.0	No adverse impact and the higher MWRA limit will help reduce corrosion in collection system.*
Phenanthrene	Prohibited	Move to TTO list – revised limits will be 1.0 mg/l	There is no technical basis for a lower limit than the other organics on TTO list.
Phenolic Compounds	0.5	Move onto TTO list – revised limit will be 1.0 mg/l	There is no technical basis for a lower limit than the other organics on TTO list.
Trichloroethylene	0.07	Move onto TTO list – revised limit will be 1.0 mg/l	There is no technical basis for lower limit than other organics on TTO list.
*Raising the upper pH limit will reduce the amount of sulfuric acid that industries with pH neutralization systems will have to add to their discharge to lower a high pH, thereby lowering the contribution of sulfide forming compounds to the MWRA sewerage system.

Table 3 Limits Proposed to be Replaced

Substance	Existing Limit (mg/l)	Proposed Action	Justification
Petroleum Hydrocarbons	15	Replace PHC limit with existing TTO, FOG, and explosivity limits, and gas/oil separator rule. Add narrative prohibiting oil disposal except as incidental to an industrial process.	There is no longer a PHC limit in the MWRA’s NPDES Permit on which to base a PHC limit in the Sewer Use Regulations. The analysis indicated that a more relevant approach is to use the TTO test which covers the toxic components of the PHCs in combination with the total oil and grease limit already in the regulations.

Final changes to the Sewer Use Regulations will be proposed for the Board’s adoption in the Spring of 2001 as a result of the local limits analysis and the public review process.

Budget/Fiscal Impact on Industries:

There will be a slight increase in testing costs for industries that now sample for PHCs. These industries now pay approximately $100 per PHC sample and they will pay approximately $400 for a total toxic organics sample under the proposed revision. The highest increase will be to about 33 industries that are now required to only take PHC samples. Those industries that are required to take both PHC and TTO samples now, will incur almost no changes to their sampling costs.

TRAC and its consultant have been considering the economic effect to the regulated community to the proposed changes in the local limits, but the analysis cannot be finalized until after comments are received from industries during the public comment period. However, preliminary results from the economic analysis indicate that these proposed changes will not have a significant adverse effect on the regulated industries.

II. STUDY SUMMARY

The MWRA has an extensive set of metals and organics data available for use in local limits development. Data were analyzed from multiple locations within the Deer Island Treatment Plant and at locations around the MWRA service area, with representative data for plant influent, and effluent, pellet quality, residential, and industrial, discharge, infiltration, water supply, and corrosion. This data was used to calculate the pollutant loadings from various sources and to calculate the relevant removal rates within the plant. These data were collected during the 27 month period from January 1997 through March 1999.

The major steps in conducting a local limits analysis are:

Determine the pollutants of concern
Develop the maximum allowable headworks loadings
Determine the influent loadings of pollutants of concern
Determine the allocation method for pollutants of concern.

In determining the pollutants of concern the following approach was used:

Include all pollutants with an existing MWRA limit or prohibition
Include the ten mandatory pollutants (heavy metals and cyanide) listed in the EPA Guidance Manual
Evaluate other Clean Water Act priority pollutants using the screening process outlined in the EPA Guidance Manual
Consider including pollutants with detection limits much greater than water quality criteria
Consider including pollutants based on potential future regulatory\enforcement considerations

For the purpose of the determining the pollutants of concern, data reported to be at non-detectable levels was assumed to be equal to the detection limit. Tables 2.1 and 2.2 list the results of the pollutants of concern determination and the frequency each pollutant of concern was detected in the influent and secondary effluent.

The next step involves determining the maximum allowable headworks loadings which is the maximum influent loading levels for individual pollutants that, based on historical POTW operations and existing regulatory criteria, would enable the POTW to meet all regulatory and worker health and safety. The maximum allowable headworks loadings were calculated using Prelim 5.0, the analysis software recommended by the EPA.

Deer Island Treatment Plant loadings were characterized as being attributable to one of the following 9 influent sources:

Water supply
Infiltration
Inflow
Corrosion
Residential
Septage
Industrial
Known commercial
Other commercial

Finally, in order to determine what limit ought to be established for industries, the Deer Island Treatment Plant loadings are allocated among the 9 sources outlined above. These allocations were determined by examining the current loadings from each source described above and calculating what loading reduction would be necessary so that the Deer Island Treatment Plant influent loading would be less than or equal to the maximum allowable headworks loading. The traditional approach to allocating influent loadings is to assume that reduction can only come from controllable sources (e.g. industries) and not from what is assumed to be uncontrollable (e.g. residential, commercial). This analysis takes a more comprehensive review of loadings allocation and looks at each contributing source and what reasonable reductions might be achievable if reductions are needed to reach the maximum allowable headworks loading.

III. DISCUSSION OF KEY ISSUES

Copper:

The average copper concentration in the MWRA’s pellets is currently at approximately 85% of DEP's Type 1 standard for unrestricted re-use, and it exceeded the concentration allowed at the headworks calculated by the local limits analysis. The results of the local limits analysis, as well as other work done by MWRA indicate that a multifaceted approach to reducing copper will be needed because there are multiple sources of copper in the MWRA system. Lowering the discharge limit to 1.0 mg/l is one facet of the approach. Other parts of the copper reduction strategy include continuing efforts to optimize MWRA's corrosion control programs for drinking water, to reduce infiltration, and to expand the distribution of educational materials to residential customers and commercial establishments containing information on products that contribute copper to the sewer system and how they can reduce the use of these products. Some slight reductions in copper are expected from implementing better controls on dental facilities (due to copper content in dental amalgams) and optimizing cooling tower operations.

Mercury:

Mercury is currently at less than 50% of DEP's most stringent limit for unrestricted re-use of pellets, and current DITP influent loadings are currently 44% below the allowable concentration at the headworks calculated by the local limits analysis. However, mercury is known to be a highly toxic metal in many chemical forms and has considerable potential for bioaccumulation within the environment. In response to these concerns, the Commonwealth has established an initiative to implement a statewide mercury action plan for the virtual elimination of mercury releases to the environment. Governor Celluci, together with the five other New England Governors and the five Eastern Canadian Premiers entered into an agreement to develop a Mercury Action Plan "to begin to address mercury releases and resulting public health and environmental impacts". In order to support the Commonwealth’s initiative and maintain a high level of control over dischargers of mercury, the staff is proposing to maintain the prohibition with an enforcement limit that will be reduced over time to 1 ppb, effective July 1, 2002. This date will give industries with a mercury discharge above 1 ppb the necessary time to evaluate and implement mercury controls. Until the effective date, the MWRA will continue with the prohibition and a revised safe harbor program. Prior to the effective date of the revised local limits regulations, staff will develop specific enforcement guidelines to implement this recommendation. As of July 1, 2002, no further safe harbor from enforcement is planned for facilities that exceed the 1 ppb enforcement limit. Prior to July 1, 2002, staff will review emerging pretreatment technologies and analytical procedures that are available to facilities to help meet this limit.

This proposed action is one component in a multifaceted MWRA approach to effectively control mercury discharges to the collection and treatment systems. The other key elements in MWRA mercury control program, which are expected to result in a net decrease over time to the mercury loads at the Deer Island Treatment Plant, include:

Work with area hospitals and other industrial/institutional dischargers of mercury to implement Best Management Practices (BMPs) to reduce mercury discharges: A number of mercury reduction techniques have been identified by the MWRA/Hospital Work Group and successfully applied by many medical facilities. MWRA will work closely with area facilities that routinely sample for mercury or use known mercury-containing products to help assure that they implement and maintain a program of BMPs for mercury control and reduction. At a minimum those practices will include identification of mercury sources, replacement of mercury-containing products with mercury-free products where feasible, and segregation of sources of high levels of mercury to prevent their discharge to the sewer system. This program will remain in place until July 1, 2002, when the facilities will be required to comply with the mercury enforcement limit through the use of source reduction BMPs, pretreatment, or a combination of approaches.

Develop a set of mandatory Best Management Practices (BMPs) for dental facilities, and a requirement that dental facilities install amalgam separators, to be endorsed and implemented with the assistance of the Massachusetts Dental Society: MWRA has been working closely with the Massachusetts Dental Society (MDS) to develop effective techniques for control and removal of mercury-bearing wastes (principally from mercury fillings) that are discharged to MWRA’s sewer system from dental facilities. The MDS recently formed a task force to work with the MWRA to develop a set of effective BMPs for mercury control, and staff will participate in a series of working sessions with MDS representatives to develop and implement these BMPs. MWRA will also continue to review amalgam separators and test protocols with the goal of identifying technologies that dental facilities will use to reduce significantly the amount of dental mercury that enters the sewer. (MWRA will implement the requirements through either a group permit for dental facilities or a "permit-by-rule," based on the outcome of the discussions with the MDS and others about which mechanism is best suited for the nature of the controls that will be adopted. MWRA will then propose regulations to implement that option.)

Maintain active participation in the state's Mercury Task Force: MWRA will continue to work actively on the EOEA Mercury Task Force, and promote the adoption of statewide minimum standards for industrial pretreatment programs, in order to reduce statewide releases of mercury to the environment. MWRA will also provide technical assistance to EOEA for rollout of a statewide program to reduce the discharges of mercury from dental facilities to Massachusetts wastewater utilities, and participate in the development of the Northeast Regional Mercury Action Plan.

Continue technical support role to legislative efforts to implement mercury product labeling and phase-out legislation: MWRA will continue to assist in state legislative efforts (such as HR No. 4803: An Act Regulating Products Containing Mercury) to ensure that mercury-containing products are properly labeled and recycled, and consumers are informed about mercury content in these products.

Molybdenum:

Although molybdenum is not currently regulated by the MWRA, it was a significant focus of the local limits analysis because it is regulated in biosolids that are beneficially used. Staff is not recommending establishing a molybdenum limit at this time, but is recommending a continuation of the voluntary molybdenum reduction program, as it has been successful in reducing molybdenum influent levels by approximately 60% since 1994.

The average influent loadings for molybdenum are 70% of the allowable concentration at the headworks calculated by the local limits analysis. The concentration of molybdenum in MWRA pellets is well below (less than 50%) the current federal standard. During FY99, the MWRA pellets met the Massachusetts DEP standard for molybdenum; however there were seasonal exceedances of the DEP standard last fall, indicative of the peak seasonal use of molybdenum as a corrosion control product in cooling towers. However, these exceedances have not affected MWRA's ability to market its pellets; sufficient stocks of pellets are expected to be available to meet all in-state distribution needs.

MWRA's voluntary molybdenum reduction effort has successfully decreased molybdenum influent loads from 90 lbs/day in FY94 to 38.4 lbs/day in FY99. This program will continue to be promoted, with an additional emphasis on minimizing the discharge of blowdown waters and the draining of closed loop systems during peak load periods.

If a more stringent federal limit on biosolids reuse is imposed, then staff will reopen the review of the molybdenum limit and assess the need to impose additional control measures. One option that has been considered during this local limits analysis is to implement a ban on the use of molybdate-based corrosion inhibitors for use in "comfort" (residential/commercial) cooling tower applications. Staff will continue to closely monitor the status of the EPA standards.

PHCs:

The MWRA’s new NPDES Permit does not contain a petroleum limit. Past NPDES permits have contained a PHC limit. Without a specific petroleum limit in the permit, the MWRA’s PHC limit is not considered to be necessary since many of the toxic pollutants covered by the total PHC limit are included in the Total Toxic Organics (TTOs) list. In addition, the MWRA has a

total fats, oil and grease limit, as well as narrative restrictions on visible oil sheens and explosivity in the sewer use regulations. Additionally, MWRA regulations will be amended to prohibit disposal of waste oil (except as ancillary to an industrial process and consistent with the other regulations). Therefore, the proposal is to replace the existing PHC limit of 15 mg/l with the TTO limits (1 mg/l for any individual TTO and 5 mg/l for any combination of organics on the TTO list), the FOG limit of 300 mg/l, and the narrative restrictions.

Acrolein:

MWRA has historically listed acrolein as a pesticide and prohibited its discharge into the sewer system. The primary use of acrolein in the MWRA Sewer Service Area is not typically as a pesticide, but rather as a by-product of certain industrial processes. Therefore, the MWRA would prefer to enforce a specific limit for acrolein based on its associated water quality and worker risks rather than enforce a blanket prohibition. The fume toxicity analysis determined that collection system workers should be protected if acrolein were discharged at levels at or below 0.15 mg/l. Acrolein has not been detected in the influent and effluent of the DITP.

Boron:

The local limits analysis indicates that the influent loadings are 28% of the calculated allowable headworks loadings. Boron is regulated primarily because there are state and federal limits for boron for biosolids that are beneficially used. The boron concentration in MWRA’s pellets has remained below detectable levels since February 1998, and have never been higher than 10% of the most stringent state standard for reuse. Staff recommends eliminating the boron limit because the analysis shows that there is no need to regulate boron at this time. MWRA has not regulated boron dischargers over the past few years and has not seen an increase in boron loadings subsequent to this suspension of enforcement of the existing limit.

Hexachlorobutadiene, Vinyl chloride, Vinylidene chloride, Dichlorodifluoromethane:

The limits for these four organic compounds are proposed to decrease due to fume toxicity concerns in the collection system. They are currently on the TTO list and as such are regulated at 1 mg/l. The fume toxicity analysis indicated that these compounds should be regulated at a lower level to protect worker health and safety for employees working in sewer lines.

Pentachlorophenol:

The current limit on Pentachlorophenol is .05 mg/l. However, pentachlorophenol is a pesticide and the limit for pesticides in the Sewer Use Regulations is prohibited. This local limits analysis recommends keeping pesticides prohibited and setting enforcement limits for each pesticide based on the detection limit for each pesticide. Therefore, staff recommends that pentachlorophenol be included on the prohibited pesticide list and as such, prohibited.

Chlorinated Naphthalenes, Phenanthrene, Phenolic compounds, and Trichloroethylene:

These organics compounds are not included on the TTO list and currently have individual limits that are lower than the 1 mg/l at which the TTOs are regulated. The local limits analysis indicates that there is no technical basis for these organic compounds to be regulated at a lower concentration than those organics on the TTO list. Therefore, the proposal is to include each of these on the TTO list, which means they will be regulated individually at 1 mg/l and will be included in the calculation of the total toxic organics, which cannot exceed 5 mg/l.

Formaldehyde:

Formaldehyde is a fume toxicity issue for worker health and safety, therefore, a maximum allowable headworks calculation is not the determining factor for formaldehyde because it does not cause plant interference or pass-through. The fume toxicity analysis for formaldehyde revealed mixed results. The EPA screening level listed in the guidance documentation is .07 mg/l and resulted in a diluted discharge limit of 1.4 mg/l using a 20:1 dilution. In contrast, analytical results using the ACGIH data for short term exposure level give a "calculated allowable liquid concentration" of 9.2 mg/l, that, with the 20:1 dilution factor, indicates a higher discharge level of 184 mg/l would be acceptable in controlling fume toxicity.

Given the large disparity between the two valid methodologies, MWRA also reviewed other factors surrounding the formaldehyde limit. A review of all industry data from January 1997 through March 1999 showed that ninety five percent of the industries’ samples for formaldehyde were at or below 5 mg/l and that eighty percent of the industries’ samples were at or below the existing limit of 1.0 mg/l. In addition, industries have expressed concern that the existing limit of 1 mg/l is difficult to meet even with proper housekeeping procedures, because they and their suppliers have claimed formaldehyde is created in the effluent of certain blood autoanalyzers and is found in many substances within the health care industry. Many permitted facilities have been required to haul their waste at great expense in order to meet the existing limit.

Therefore, MWRA reviewed the existing analysis described above and outlined the possible limits. A limit of 1.4 mg/l or 184 mg/l would be the result with dilution; without dilution we would have limits of .07 mg/l or 9.2 mg/l. If the limit were based on the ninety-fifth percentile of industrial samples, it would be 5 mg/l. There was serious concern among MWRA staff that setting a limit as high as 184 mg/l was effectively removing all controls. This would produce wholesale backsliding and negate the formaldehyde reductions already made by many facilities. Data on formaldehyde also indicates that it is a carcinogen that will biodegrade to low levels in a few days.

MWRA staff also recognized the difficulty that some facilities have had in consistently reaching the 1 mg/l limit without considerable expense. Therefore, the goal was to determine a technically sound limit between 1 mg/l and 184 mg/l that is protective of worker health and safety. Based on the available data, MWRA has determined that a formaldehyde limit of 9.0 mg/l, calculated from the ACGIH short term exposure level rounded down to the nearest whole number without dilution, best meets its requirements.

Sulfates:

The local limits analysis included a preliminary review of the sulfate data from across the MWRA sewer service area and concluded that it was not necessary to establish system-wide limits for sulfates at this time, but that sulfate limits should be imposed on a site-specific basis. This site-specific review has begun.

IV. SUMMARY OF ANALYSIS RESULTS

Acrolein

Listed as a pesticide and prohibited from discharge into the sewer system.
Has not historically been detected in the influent or effluent of the DITP.
MWRA staff have determined that the presence of acrolein in permitted industrial discharges is not typically as a pesticide, but rather as a by-product of certain industrial processes.
The fume toxicity analysis determined that collection system workers should be protected if acrolein were discharged at levels at or below 0.15 mg/L.

Recommendation: Adjust acrolein limit to 0.15 mg/L. Prohibition does not adequately account for occurrence of acrolein as a by-product of acceptable industrial processes. Continue to discourage use of acrolein-containing pesticides as part of public outreach efforts.

Antimony

Current antimony limit is 10 mg/L
Local Limits analysis indicates that influent loadings are less than one percent of Maximum Allowable Headworks Loadings (MAHL)
MAHL includes a 10% safety factor
MAHL based on water quality criteria
No recorded industrial violations of the antimony limit during the study period (January 1997-March 1999)
95^th percentile discharge concentration from monitored industries = 0.15 mg/L

Recommendation: Retain 10 mg/L limit. Current limit does not seem to be causing any industrial compliance problems and is adequately protecting receiving water quality.

Arsenic

Current arsenic limit is 0.5 mg/L
MAHL analysis indicates that influent loadings are about 32 percent of MAHL
MAHL includes a 10% safety factor
MAHL based on sludge limits
Only a total of six industrial violations, from three facilities, of the arsenic limit were recorded during the study period (January 1997-March 1999)

Recommendation: Retain 0.5 mg/L limit. Current limit does not seem to be causing significant industrial compliance problems and is adequately protecting receiving water quality, the treatment plant, and biosolids.

Benzene

Current benzene limit is 1.0 mg/L (TTO).
No industrial violations of the benzene limit were recorded during the study period (January 1997-March 1999)
Benzene poses a fume toxicity risk at discharge concentrations greater than 0.3 mg/L.

Recommendation: Lower limit to 0.3 mg/L. Maintain on TTO list so that total toxic organics measurements will include benzene. Current limit does not adequately protect against fume toxicity.

Boron

Current boron limit is 20 mg/L
MAHL analysis indicates that influent loadings were at about 28 percent of MAHL during the study period
MAHL includes a 10% safety factor
MAHL based on sludge limits
Some extreme historical excursions of boron limit by the monitored industries
No significant additional boron discharges are expected to the MWRA system in the near future.

Recommendation: Eliminate the boron limit. The influent loadings are 28% of the calculated allowable headworks loadings. Boronhas not been detected it in the pellets since February 1998.

Cadmium

Current cadmium limit is 0.1 mg/L
MAHL analysis indicates that influent loadings are about 70 percent of MAHL
MAHL includes a 10% safety factor
MAHL based on sludge limits
Only a total of seven industrial violations, from five facilities, of the cadmium limit were recorded during the study period (January 1997-March 1999)

Recommendation: Retain 0.1 mg/L limit. Current limit does not seem to be causing significant industrial compliance problems and is adequately protecting receiving water quality, the treatment plant, and biosolids.

Chlorinated Naphthalenes

Current limit for chlorinated naphthalenes is 0.8 mg/L, but the basis for this limit is unknown
The only chlorinated naphthalene that is a priority pollutant is 2-chloronaphthalene
2-chloronaphthalene was not detected during the study period
No recorded industrial violations of the chlorinated naphthalenes limit during the study period (January 1997-March 1999)

Recommendation: Raise limit to 1 mg/L (TTO). There does not appear to be a need to separate out chlorinated naphthalenes from the other toxic organics.

The TTO list already includes 2-chloronaphthalene; this listing should remain and the separate listing for chlorinated naphthalenes should be eliminated.

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Chromium (Total)

Current total chromium limit is 1.0 mg/L
MAHL analysis indicates that influent loadings are about 8 percent of MAHL
MAHL includes a 10% safety factor
MAHL based on sludge limits
During the study period (January 1997-March 1999), there were a total of 22 recorded industrial violations of the total chromium limit from 13 facilities.
95^th percentile discharge concentration from monitored industries = 0.25 mg/L

Recommendation: Retain 1.0 mg/L limit. Current limit does not seem to be causing significant industrial compliance problems and is protecting receiving water quality, the treatment plant, and biosolids.

Chromium, Hexavalent

Current hexavalent chromium limit is 0.5 mg/L
Hexavalent chromium was never detected in the DITP influent during the study period (January 1997-March 1999)
During the study period (January 1997-March 1999), there were a total of 10 recorded industrial violations of the hexavalent chromium limit from 6 facilities.
95^th percentile discharge concentration from monitored industries is 0.19 mg/L

Recommendation: Retain 0.5 mg/L limit. Current limit does not seem to be causing significant industrial compliance problems and is adequately protecting receiving water quality, the treatment plant, and biosolids.

Copper

Current limit is 1.5 mg/L
Targeted pollutant – DITP loadings exceed MAHL by roughly 30 ppd

-- MAHL conservative by roughly 10 percent due to removal rate methodology

Historical exceedances of sludge limit, but typically in compliance
Industrial loadings only 3 % of DITP influent (about 7 pounds per day, net)
Need to address other loading sectors to approach MAHL
Should be able to lower local limit without significant impacts on permitted discharges

-- 95^th percentile for all industries is 1.0 mg/L

-- 95^th percentile for medical industries is1.3 mg/L

Recommendation: Lower limit to 1.0 mg/L as part of a larger copper reduction program to promote additional reductions from the permitted and unpermitted dischargers. Strive towards attainment of MAHL by targeting reasonable reductions from a balance of loading sources: corrosion control, public education, and BMPs applied primarily to commercial and residential sector.

Cyanide

Current cyanide limit is 0.5 mg/L
Current limit 0.5 mg/L matches limit at other progressive POTWs
Cyanide was only detected on 2% of the occasions when DITP influent from the study period (January 1997-March 1999) was sampled
Cyanide was detected at numerous industrial facilities during the study period (January 1997-March 1999)
Total of 41 industrial violations of the cyanide limit during the study period (January 1997-March 1999) committed by 16 facilities
MAHL analysis indicates that influent loadings are about four percent of MAHL
MAHL includes a 10% safety factor

Recommendation: Retain 0.5 mg/L limit. Current limit is protecting receiving water quality, the treatment plant, and biosolids.

Fat, Oil, and Grease

Current fat, oil, and grease limit is 300 mg/L
Fat, oil, and grease was detected on all of the occasions when DITP influent from the study period (January 1997-March 1999) was sampled
Fat, oil, and grease was detected at numerous industrial facilities during the study period (January 1997-March 1999)
Total of 85 industrial violations of the fat, oil, and grease limit during the study period (January 1997-March 1999) committed by 22 facilities

Recommendation: Retain 300 mg/L limit. Current limit is protecting receiving water quality, collection system, and the treatment plant. Petroleum hydrocarbons are included as a component of total oil and grease. Some industries are experiencing compliance problems. This limit should be readily attainable with proper grease separation facilities.

Fluoranthene

Current fluoranthene limit is 1.5 mg/L
MAHL based on water quality criteria
Fluoranthene was never detected in DITP influent during the study period (January 1997-March 1999)
Fluoranthene was only detected at two industrial facilities during the study period (January 1997-March 1999)
No recorded industrial violations of the fluoranthene limit during the study period

Recommendation: Lower limit to 1.0 mg/L and maintain on TTO list. There does not appear to be a need to separate out fluoranthene from the other toxic organics.

Hexachlorobutadiene

Current Hexachlorobutadiene limit is 3.0 mg/L
Hexachlorobutadiene was never detected in DITP influent during the study period (January 1997-March 1999)
Hexachlorobutadiene was only detected at one industrial facility during the study period (January 1997-March 1999)
No recorded industrial violations of the Hexachlorobutadiene limit during the study period
Hexachlorobutadiene poses a fume toxicity risk at discharge concentrations greater than 0.004 mg/L.

Recommendation: Prohibit with reference to an enforcement limit determined by the MWRA Central Laboratory. Current limit does not adequately protect against fume toxicity and concentration limit required to do so is below detection limit for hexachlorobutadiene analysis.

Lead

Current limit is 0.2 mg/L
DITP influent loadings are at approximately 91% of the calculated MAHL
MAHL includes a 10% safety factor
Historical exceedances of sludge limit, but typically in compliance
Industrial loadings only 3 % of DITP influent (about 1.3 pounds per day, net)
Current limit appears to be at a very reasonable level

-- 95^th percentile for all industries is 0.2 mg/L

Recommendation: Retain 0.2 mg/L limit. No reductions required to reach MAHL. Reductions should come due to reduction measures instituted for copper reduction. These reduction measures include corrosion control, public education, and Best Management Practices applied primarily to commercial and residential sector.

Mercury

Mercury is currently prohibited from discharge in the MWRA service area
Enforcement limit is 1 ug/L
Mercury has been receiving much attention and scrutiny by EPA and environmental groups due to its toxicity and bioaccumulative characteristics
The Commonwealth has established an initiative to implement a statewide mercury action plan for the virtual elimination of mercury releases to the environment
High number of industrial discharge violations have occurred for mercury
Mercury is commonly detected in DITP influent, effluent, and sludge
Influent loadings are currently below MAHL by nearly 50 percent
MAHL dictated by sludge limits (generally below DEP limit by roughly 50 percent, with 2-3 spikes approaching/exceeding limit during study period)
Dentists are the largest known source of mercury loadings

Recommendation: Maintain the current prohibition on mercury dischargers with an enforcement limit of 1 ug/l with an effective date of July 1, 2002, in order to support the Commonwealth’s mercury reduction initiative. Continue a revised safe harbor program until, July 1, 2002, to give industries with a mercury discharge above 1 ug/l time to evaluate and implement mercury controls. Using regulatory controls, require dental facilities to install readily available treatment units, which are expected to reduce known commercial discharges by approximately 80 percent and work with permitted dischargers of mercury to implement Best Management Practices to further reduce mercury discharges. Work with EOEA on Commonwealth’s virtual elimination strategy and product legislation to help reduce mercury levels from other sources.

Nickel

Current nickel limit is 1.0 mg/L
MAHL analysis indicates that influent loadings are about 19 percent of MAHL
MAHL includes a 10% safety factor
MAHL based on sludge limits
Total of 25 industrial violations, from 14 facilities, of the nickel limit were recorded during the study period (January 1997-March 1999)
95^th percentile discharge concentration from monitored industries = 0.43 mg/L

Recommendation: Retain 1.0 mg/L limit. Current limit does not seem to be causing significant industrial compliance problems and is protecting the receiving water quality, the treatment plant, and biosolids.

Pentachlorophenol

Pentachlorophenol is a pesticide
The MWRA currently prohibits pesticide discharges
Current pentachlorophenol limit is 0.05 mg/L
Pentachlorophenol was never detected in DITP influent during the study period (January 1997-March 1999)
Pentachlorophenol was only detected at one industrial facility during the study period (January 1997-March 1999)
No recorded industrial violations of the pentachlorophenol limit during the study period (January 1997-March 1999)

Recommendation: Prohibit as other pesticides are prohibited.

Current pH limit is 5.5-10.5 units
Total of 111 facilities with pH violations with approximately 25% exceeding the upper limit of 10.5 units
Lower limit is necessary to minimize sulfide generation and associated corrosion
A higher pH level in the wastewater would be beneficial to minimize sulfide generation within the sewers
pH levels of 12.5 or above are considered hazardous
Raising upper limit to 12.0 would allow more high-pH discharges, which could help protect MWRA’s infrastructure

Recommendation: Raise upper limit to 12 units. This should allow about 25% of the industries that have committed violations to be in compliance while not negatively effecting the collection or treatment systems.

Phenanthrene

Phenanthrene is currently prohibited from sewer discharge in the MWRA service area
Prohibition apparently based on application of expected water quality criterion that has not been implemented
No evidence of current or expected water quality criterion for phenanthrene

Recommendation: In the absence of a basis for its prohibition, return phenanthrene limit to 1.0 mg/L and add to TTO list.

Phenol

Current phenol limit is 5.0 mg/L
MAHL analysis indicates that influent loadings are less than one percent of MAHL
MAHL includes a 10% safety factor
MAHL based on nitrification inhibition literature value from Guidance Manual
No industrial violations were recorded during the study period (January 1997-March 1999)

Recommendation: Retain 5.0 mg/L limit. Current limit is not causing any industrial compliance problems and is protecting receiving water quality, the treatment plant, and biosolids.

Phenolic Compounds

Current limit for phenolic compounds is 0.5 mg/L
Phenolic compounds, as defined by the MWRA, include the phenolic compounds that are priority pollutants excluding pentachlorophenol and phenol, which are limited separately
No recorded industrial violations of the phenolic compounds limit during the study period (January 1997-March 1999)

Recommendation: Raise limit to 1 mg/L (TTO) and include all priority pollutant phenolic compounds, except phenol, on the TTO list. There does not appear to be a need to separate out phenolic compounds from the other toxic organics.

Pesticides

MWRA currently samples for each of the pesticides listed as priority pollutants in the Clean Water Act. Of these 25 listed pesticides, 10 were detected in either the MWRA influent or effluent during the study period. Other pesticides exist that are not analyzed by MWRA.
None of the pesticides were detected at levels that would exceed water quality standards at the new DITP outfall discharge point

-- Only 4,4’ DDT was present in the final effluent at a level greater than _ the Water Quality Standard

-- Toxaphene was not detected, but the detection limit is greater than 50 times the Water Quality Standard

Pesticides are already prohibited from sewer discharge in the MWRA service area
Whole Effluent Toxicity tests do not indicate the presence of unacceptable levels of toxicity in the DITP effluent
No evidence exists to change the current approach to regulating pesticides
As a preventative measure, TRAC could consider additional pollution prevention strategies to promote additional control of pesticides:

-- Permitted industries could (continue to?) analyze/report pesticide levels in their discharge

-- Public outreach / education to minimize pesticide use/discharge

-- Promote urban and suburban runoff control measures

Recommendation:Continue to prohibit pesticides as a group. Any detection of pesticides should be investigated / enforced. Pollution prevention and public outreach/control efforts should be initiated to minimize future toxicity potential. Regulations should allow for the use of certain substances, such as bleach, which could be classified as pesticides, but their main use is not as a pesticide.

Petroleum Hydrocarbons (PHCs)

Current limit for petroleum based oil and grease (operational definition of PHCs) of 15 mg/L
Historical limit based on former 15 mg/L NPDES discharge permit requirement; this requirement is not in current permit
MWRA already enforces a total oil and grease limit of 300 mg/L and narrative restrictions on odor, toxicity, and explosivity
Laboratory / sampling staff report that this limit is confusing to dischargers and staff
No apparent basis exists for a separate PHC limit

Recommendation: Replace the PHC limit with the TTO limits and the FOG limit. Any concerns for PHCs will be addressed through the TTO limits, and the total fats, oil and grease limit, plus the narrative restrictions. Ensure that petroleum hydrocarbons are measured as part of total fats, oil and grease. Prohibit dumping of used oil into drains and continue aggressive management of oil/gas trap installation and maintenance requirements.

Polychlorinated Biphenyls (PCBs)

Currently prohibited from sewer discharge in the MWRA service area
Not detected in influent/effluent of DITP during study period
Aroclor 1260 detected in biosolids pellets at levels below permit limits; all other aroclors undetected in pellets
PCBs still a major concern for EPA, DEP, National Marine Fisheries Service, and MWRA
No reason to change prohibition of PCBs
MWRA already developing a special control plan for PCBs as required in the final NPDES Permit

Recommendation: Retain current prohibition for PCBs

Selenium

Current selenium limit is 5.0 mg/L
MAHL analysis indicates that influent loadings are about 20 percent of MAHL
MAHL includes a 10% safety factor
MAHL based on sludge limits
No industrial violations of the selenium limit were recorded during the study period (January 1997-March 1999)
95^th percentile discharge concentration from monitored industries = 0.1 mg/L

Recommendation: Retain 5.0 mg/L limit. Current limit is not causing industrial compliance problems and is protecting receiving water quality, the treatment plant, and biosolids.

Silver

Current silver limit is 2.0 mg/L
MAHL analysis indicates that influent loadings are about 10 percent of MAHL
MAHL includes a 10% safety factor
MAHL based on anaerobic digestion literature limit from Guidance Manual
The discharge concentration data set includes 72 samples (out of 2807) that exceeded 2.0 mg/L.
Discharge levels that exceeded 2.0 mg/L were primarily from photoprocessors, printing operations, and medical facilities
95^th percentile discharge concentration from monitored industries is 0.94 mg/L
97^th percentile discharge concentration from monitored industries is 2.0 mg/L

Recommendation: Retain 2.0 mg/L limit. The majority (97%) of the industrial samples were at or below 2.0 mg/l

Total Toxic Organics

MWRA currently has a local limit of 1 mg/L for individual TTOs and 5 mg/L for total TTOs in a given industrial discharge.
While there is unlikely to be a technical basis for any specific individual TTO limit, the 1 mg/L / 5 mg/L limits are commonly used, and are comparable to EPA categorical limits for certain industry sectors

-- EPA set a categorical limit of 2.13 mg/L for large dischargers (>10,000 gpd) in the metal finishing and electroplating category

-- EPA set a categorical limit of 1.37 mg/L for the electrical and electronic components category

Given that effluent toxicity is not a major concern right now for MWRA, there does not appear to be any need to reevaluate / modify this limit
Note that based on conclusions for some of the other pollutants of concern, MWRA may want to expand the current TTO list to include a few additional chemicals

Recommendation: Retain the existing TTO limits of 1 mg/L and 5 mg/L (total). Modify the list of TTOs as appropriate to incorporate latest thinking for other pollutants of concern. The final TTO list should contain all toxic organics that the MWRA wishes to limit at 1.0 mg/L or lower.

Trichloroethylene

Current trichloroethylene limit is 0.07 mg/L
Limit of 0.07 mg/L was developed based on anaerobic digestion inhibition criteria. Calculations assumed that trichloroethylene is a conservative pollutant and that the amount removed during treatment all goes to the anaerobic digesters.
Trichloroethylene is not a conservative pollutant and removal through biodegradation as well as volatilization should have been considered in previous analysis
The current MAHL analysis accounted for biodegradation and volatilization.
MAHL analysis indicates that influent loadings (9.8 lbs/day) are about 16 percent of the MAHL (60.9 lbs/day).
MAHL includes a 10% safety factor
MAHL based on anaerobic digestion inhibition criteria from Guidance Manual.
Total of 15 industrial violations of the trichloroethylene limit, committed by 14 facilities, were recorded during the study period (January 1997-March 1999)

Recommendation: Raise limit to 1 mg/L (TTO) and add to the TTO list. There does not appear to be a need to separate out trichloroethylene from the other toxic organics.

Vinyl Chloride

Current vinyl chloride limit is 1.0 mg/L (TTO).
No industrial violations of the vinyl chloride limit were recorded during the study period (January 1997-March 1999)
Vinyl chloride poses a fume toxicity risk at discharge concentrations greater than 0.02 mg/L.

Recommendation: Lower limit to 0.02 mg/L and remove from TTO list. Current limit does not adequately protect against fume toxicity.

Vinylidene Chloride (1,1 – Dichloroethene)

Current vinylidene chloride limit is 1.0 mg/L (TTO).
No industrial violations of the vinylidene chloride limit were recorded during the study period (January 1997-March 1999)
Vinylidene chloride poses a fume toxicity risk at discharge concentrations greater than 0.3 mg/L.

Recommendation: Lower limit to 0.3 mg/L and remove from TTO list. Current limit does not adequately protect against fume toxicity.

Zinc

Current zinc limit is 1.0 mg/L
MAHL analysis indicates that influent loadings are about 88 percent of MAHL
MAHL includes a 10% safety factor
MAHL based on secondary treatment process inhibition limits from the Guidance Manual
Total of 164 industrial violations, from 58 facilities, of the zinc limit were recorded during the study period (January 1997-March 1999)

Recommendation: Retain 1.0 mg/L limit. Current limit is protecting receiving water quality, the treatment plant, and biosolids. Some industries are experiencing compliance problems. Consider introducing compliance-based trading for interested permittees.

NEW LIMITS

Dichlorodifluoromethane

No local limit currently exists for Dichlorodifluoromethane
Dichlorodifluoromethane poses a fume toxicity risk at discharge concentrations greater than 3.0 mg/L.
Dichlorodifluoromethane is not monitored by the MWRA

Recommendation: Add dichlorodifluoromethane to the TTO list, which sets its limit at 1.0 mg/L to protect against potential fume toxicity.

OTHER POLLUTANTS CONSIDERED

Dioxin

Not currently regulated by EPA or DEP; no water quality standard or sludge limit exists
No local limit currently in place by MWRA
Dioxins are becoming of increasing concern to EPA and general public as a bioaccumulative pollutant. The EPA has published a proposed numeric limit for dioxins in biosolids of 300 ppt toxic equivalents of dioxins and intends to publish a final rule by December 2001.
No specific evidence or basis exists to establish a technically-based local limit for dioxin at this time
MWRA may want to consider initiating periodic data gathering for dioxins at the DITP and/or industries with combustion processes/incinerators in order to be educated as to existing levels in case regulations are forthcoming from EPA

Recommendation: Do not establish a local limit for dioxins at this time. Gather DITP and industrial data and review this issue again as part of the next local limits development effort

Molybdenum

No local limit currently exists for Molybdenum
Historical exceedances of DEP sludge limits have occurred

-- Levels have decreased during last year, but Fall spikes still exceed limit

-- Unrestricted biosolids reuse yet to be approved during Fall

MAHL analysis indicates that influent loadings (23.5 lbs/day) over the entire study period are at about 76% of MAHL (31.1 lbs/day)
MAHL includes a 10% safety factor
Molybdenum discharges are highest in the months of June through November

-- From June 1997 – November 1997, influent loadings averaged 31.1 lbs/day (27.0 lbs/day

from the north and 4.1 lbs/day from the south)

-- The peak monthly average molybdenum loading for 1997 was 33.5 lbs/day in August

-- From June 1998 – November 1998, influent loadings averaged 24.6 lbs/day (20.6 lbs/day

from the north and 4.0 lbs/day from the south)

-- The peak monthly average molybdenum loading for 1998 was 33.7 lbs/day in October

Volunteer program to minimize use in cooling towers appears to have been successful. Molybdenum loadings from the north, where the majority of cooling towers are located, decreased in 1998 compared to 1997 during the months of June through November.
Peak loadings exceeded the MAHL
Limited industrial data exist for molybdenum since it has not been regulated historically
Past efforts have determined that Mb substitutes exist for low-heat "comfort" cooling towers, and industrial facilities are testing substitutes for high-heat industrial cooling processes

Recommendation: Continue efforts to encourage facilities to participate in voluntary program of using alternatives to molybdenum. Note that a limit might be imposed in the future if it becomes more important to the MWRA to meet the MA DEP limit at all times and/or the EPA imposes a more stringent Molybdenum sludge limit that the MWRA cannot meet utilizing a voluntary program alone. If the voluntary program continues to be successful, as measured by further reductions in molybdenum levels in MWRA sludge, there would be no need for a ban. As part of MWRA outreach efforts, recommend that closed loop systems discharge during off-peak seasons when molybdenum levels in the sewer system are low.

Nitrogen

Identified as an additional pollutant of concern due to Contingency Plan outfall monitoring levels

-- monitoring level set at current DITP discharge level to track future increases/decreases

No basis for establishing a local limit at this time
May be useful to gather data on existing sources (e.g., include in TRAC monitoring), and include nutrient source reduction measures in any outreach efforts to control pesticide or other nonpoint source controls

Recommendation: Do not establish a local limit for nitrogen at this time. Consider gathering additional data on potential nitrogen sources and/or including nutrient loadings information as part of other public education/outreach measures.

Polynuclear Aromatic Hydrocarbons (PAHs)

Only 2 of the 16 have been detected in the DITP influent/effluent

-- Dibenzo(a,h) anthracene (levels not a concern for water quality standards)

-- Phenanthrene (no water quality standard exists)

Dibenzo (a,h) anthracene (and all other PAHs except for phenanthrene) are currently included in MWRA’s definition of total toxic organics (TTOs)

-- Current local limit for these TTOs is 1.0 mg/L

-- No evidence exists to change this local limit

-- No separate limit for PAHs appears necessary

Phenanthrene is currently prohibited from sewer discharge in the MWRA service area

-- Prohibition apparently based on application of expected water quality criterion that has not been implemented

-- No evidence of current or expected water quality criterion for phenanthrene

-- In the absence of convincing data to contrary, return limit to 1.0 mg/L

Recommendation: Suggest PAHs be regulated under "TTO" Category only – local limit would be 1.0 mg/L / 5.0 mg/L for total TTOs. Eliminate Phenanthrene prohibition; list as TTO.

Sulfates

No local limit currently exists for sulfates
Limited data exists on the discharge of sulfates by permitted industries
MWRA has experienced severe localized odor and corrosion problems in certain locations of its collection system that have been attributed to excessive levels of hydrogen sulfide in the system
Hydrogen sulfide (H₂S) forms in the sewer system under anaerobic conditions in the presence of sulfates and sulfides. Sulfates (SO₄^-2), which occur naturally in water supplies and domestic wastewater, can be reduced to sulfides under anaerobic conditions. Typical domestic wastewater concentrations of sulfates ranges on the order of 30 to 50 mg/L.
Many factors in addition to the concentration of sulfates and sulfides, including temperature, pH, BOD, and wastewater turbulence, often combine to determine the extent of odor and corrosion at a specific location in the sewer system
Certain industries in the service area are known to discharge extremely high concentrations of sulfates, contributing to the dissolved sulfide levels and associated promotion of H₂S formation

Recommendation: Limits on sulfates should be considered on a site-specific or municipality-specific basis based on the cost/benefits of a new limit compared to other potential odor/corrosion control measures. This separate review has begun.

Sulfides

No local limit currently exists for sulfides
Limited data exists on the discharge of sulfides by permitted industries
MWRA has experienced severe localized odor and corrosion problems in certain locations of its collection system that have been attributed to excessive levels of hydrogen sulfide in the system
Hydrogen sulfide (H₂S) forms in the sewer system under anaerobic conditions in the presence of sulfates and sulfides. Sulfates (SO₄^-2), which occur naturally in water supplies and domestic wastewater, can be reduced to sulfides under anaerobic conditions. Typical domestic wastewater concentrations of sulfates ranges on the order of 30 to 50 mg/L.
Many factors in addition to the concentration of sulfates and sulfides, including temperature, pH, BOD, and wastewater turbulence, often combine to determine the extent of odor and corrosion at a specific location in the sewer system
Certain industries in the service area are known to discharge extremely high concentrations of sulfates, contributing to the dissolved sulfide levels and associated promotion of H₂S formation

Recommendation: Limits on sulfides should be considered on a site-specific or municipality-specific basis based on the cost/benefits of a new limit compared to other potential odor/corrosion control measures. This review will be conducted as part of a separate effort.