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Managing Mercury Mania

Managing Mercury Mania. Jerald O. Thaler, P.E. Fishbeck, Thompson, Carr & Huber, Inc. Michigan Water Environment Association Annual IPP Seminar September 25, 2008. “Mercury 101”. The Wake-up Call.

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Managing Mercury Mania

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  1. Managing Mercury Mania Jerald O. Thaler, P.E. Fishbeck, Thompson, Carr & Huber, Inc. Michigan Water Environment Association Annual IPP Seminar September 25, 2008

  2. “Mercury 101”

  3. The Wake-up Call • In the 1950s and 1960s, Japan experienced an epidemic of psychotic disease and deformed/brain-damaged births • Traced to mercury poisoning from eating fish in Minamata Bay • Tons of mercury chloride was discharged by Chisso Corporation between 1931 and 1968 • Aquatic organisms convert inorganic mercury to highly toxic methylmercury • Methylmercury bioaccumulates up the food chain (~106x for trophic level 5) Bioaccumulation

  4. Regulatory Focus • Michigan has strict, long-standing controlson mercury in wastewater discharges • Only recently has focus increased on air emissions, where the impact is greater Tributaries (20%) Atmospheric Deposition (80%) Mercury Sources to Lake Michigan (adapted from Frequently Asked Questions About Atmospheric Deposition, USEPA, September 2001)

  5. Discharge Standards • Rule 57 provides protection against toxicity • Wildlife protection controls at 0.0013 μg/L, or 1.3 nanograms per liter (ng/L) • No mixing zone credit for BioaccumulativeChemicals of Concern

  6. Effluent Monitoring • Method 1631 • Grab sample • “Clean Hands/Dirty Hands” • Quantification acceptable for compliance testing • $90 each for 3 samples (duplicates plus field blank) • Method 245.1 • Composite sample • Normal handling • Quantification inconclusive for compliance testing • $40-$50 each (from Sample Collection for Ultra-Trace Concentrations of Mercury, Florida Department of Environmental Protection, ftp://ftp.dep.state.fl.us/pub/labs/assessment/ppt/utmsamp.ppt)

  7. NPDES Permit • Limits generally set at Level Currently Achievable (LCA) under multiple discharger variance • Initially 30 ng/L • Recently lowered to 10 ng/L • Soon to change to user-specific LCA • Applied as 12-month moving average • Effluent monitoring using Method 1631 • Mercury Minimization Program required

  8. Mercury Minimization Program • Goal to achieve effluent of 1.3 ng/L • Formal plan approvable by MDEQ • Annual status report • Required elements • Monitoring of influent, effluent, and biosolids • Source identification • Source reduction • Recommended elements • Public education

  9. Minimization Tips and Techniques

  10. Avoid the Regulatory Trap • Mercury in permit if potential effluent quality (PEQ) exceeds 1.3 ng/L • Per Rule 1211, PEQ is statistical tool to relate quality/quantity of monitoring data where factor set by number of samples (N): • PEQ = CMAX * Factor

  11. Avoid the Regulatory Trap • Permit application generally requires minimum of four effluent samples • Sometimes more samples may be better • If 4 samples with CMAX of 0.7 ng/L, PEQ>1.3 ng/L and permit will include mercury PEQ = 0.7*2.6= 1.8 ng/L • If 10 samples with CMAX of 0.7 ng/L, PEQ<1.3 ng/L and permit may not include mercury PEQ = 0.7*1.7= 1.2 ng/L

  12. Flexible Sewer Use Ordinance • Traditional command-and-control approach: “No discharge of detectable mercury.” • May not be feasible for some commercial users • Technical limitations • Economic factors • Strict enforcement may be counterproductive to local economy

  13. Flexible Sewer Use Ordinance • Alternative case-by-case approach: “No discharge of detectable mercury, except as specifically approved.” • Conditions of approval • Periodic self-monitoring • Minimization program (procedures, training, source identification/reduction, treatment, etc.) • All reasonable and cost-effective actions • Promotes flexibility and cooperation

  14. Identified Sources 0.05 MGD 700 ng/L Hg 0.107 lb/yr Hg Domestic/Background WWTP Influent WWTP Effluent 1.26 MGD 1.31 MGD 1.30 MGD 50 ng/L Hg 445 ng/L Hg 7.9 ng/L Hg 0.192 lb/yr Hg 1.773 lb/yr Hg 0.031 lb/yr Hg Unidentified Sources Average Removal By difference… 98% 1.474 lb/yr Hg Biosolids(6.5%) 396 T/yr 2.2 mg/kg Hg 1.742 lb/yr Hg Meaningful Monitoring • Evaluate monitoring data via mass balance to fully assess overall system • Example: Current Average

  15. Identified Sources 0.050 MGD 200 ng/L Hg 0.030 lb/yr Hg Domestic/Background WWTP Influent WWTP Effluent 1.25 MGD 1.31 MGD 1.3 MGD 50 ng/L Hg 63 ng/L Hg 1.3 ng/L Hg 0.190lb/yr Hg 0.250 lb/yr Hg 0.005 lb/yr Hg Unidentified Sources AverageRemoval By difference… 98% 0.073 lb/yr Hg Biosolids (6.5%) 396 T/yr 0.3 mg/kg Hg 0.255 lb/yr Hg Meaningful Monitoring • Apply mass balance results to prioritize minimization efforts -0.077 lb/yr -1.401 lb/yr Goal

  16. Productive Source Studies • Common sources • Domestic sewage (25-50 ng/L) • Dental offices • Other observed sources • Hospitals and medical clinics • State prisons • Car washes • Rainwater (~10 ng/L) and snowmelt • Use sampling of collection system to identify significant sources and maintain neutrality

  17. S-2 S-1 Source P-1 P-2 S-1' S-2' WWTP Productive Source Studies • Scattered sampling can be inconclusive due to high variability of mercury • Most efficient is moving upstream via “primary/secondary” scheme

  18. Deal With the Dentist • The most common controllable source of mercury • Mercury inherent to dentistry due to mercury-silver amalgams • Special challenge for smaller communities with multiple dentists

  19. Deal With the Dentist • Typical mercury generated per office 0.57 lb/yr Amalgam removal (97%) 0.02 lb/yr Amalgam placement (3%) 0.59 lb/yr Total • Removals for typical capture processes ~ 68% Chair-side traps ~ 40% Vacuum filters 81% Overall • Typical sewer discharge per office 0.59 * (1-.81) = 0.1 lb/year (ENVIRON International Corp., Evaluation of Mercury in Dental Facility Wastewater, Ver. 3, American Dental Association, Nov. 2002)

  20. Deal With the Dentist • Potential impact on treatment plant Assuming 2.5 million gal/day flow

  21. Deal With the Dentist • Amalgam Separator • >95% mercury removal for wet vacuum systems • Not overly complex or expensive • Can produce significant improvement at treatment plant • “…[Amalgam separator] systems work well, and we now feel comfortable including them in our best management practice recommendations." • Dr. Mark J. Feldman, President • American Dental Association • October 11, 2007

  22. Deal With the Dentist • Potential impact on treatment plant Again assuming 2.5 million gal/day flow

  23. Deal With the Dentist • Proposed Legislation • SB-1310/HB-6307 mandate amalgam separators by December 31, 2013 • Michigan Board of Dentistry to promulgate associated best management practices • However, prevents local authorities from pursuing further source reduction where warranted “This… supersedes any local ordinance… that imposes… additional standards on dentists… including… a permit that limits the discharge of mercury… greater than that capable of being achieved by full compliance with this section.”

  24. Perspective • Justifiable concern over mercury in waterways • Air emissions need same, or greater, scrutiny aswastewater discharges • Tips and techniques from experience • Avoid the regulatory trap • Flexible sewer use ordinance • Meaningful monitoring • Productive source studies • Deal with the dentist • Resist legislation that, while well-intended, pre-empts local authority/control

  25. For additional information: • Questions and Discussion Jerald O. Thaler, P.E. Fishbeck, Thompson, Carr & Huber, Inc. 39255 Country Club Drive, Suite B-25 Farmington Hills, MI 48331 jothaler@ftch.com 248-324-2090

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