► engineers scientists architects constructors ► 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 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 (~10 6 x for trophic level 5) Bioaccumulation

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

► Discharge Standards Rule 57 provides protection against toxicity Wildlife protection controls at μg/L, or 1.3 nanograms per liter (ng/L) No mixing zone credit for Bioaccumulative Chemicals of Concern Criterion Micrograms per liter (μg/L) Acute Toxicity2.8 Chronic Toxicity0.77 Human Health Wildlife0.0013

► Effluent Monitoring Method –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) Method 1631 –Grab sample –“Clean Hands/Dirty Hands” –Quantification acceptable for compliance testing –$90 each for 3 samples (duplicates plus field blank)

► 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

► 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

Minimization Tips and Techniques

► 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 = C MAX * Factor NFactor

► Avoid the Regulatory Trap Permit application generally requires minimum of four effluent samples Sometimes more samples may be better –If 4 samples with C MAX 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 C MAX 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

► ► 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

► 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

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

► Meaningful Monitoring Apply mass balance results to prioritize minimization efforts Identified Sources MGD 200 ng/L Hg lb/yr Hg Domestic/Background 1.25 MGD 50 ng/L Hg lb/yr Hg Unidentified Sources Average Removal lb/yr Hg By difference… 98% 0.3 mg/kg Hg lb/yr Hg WWTP Influent lb/yr Hg Biosolids (6.5%) 396 T/yr 1.31 MGD 63 ng/L Hg lb/yr Hg 1.3 ng/L Hg 1.3 MGD WWTP Effluent Goal lb/yr lb/yr

► 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

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

► 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

Typical mercury generated per office 0.57 lb/yrAmalgam removal (97%) 0.02 lb/yrAmalgam 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) ► Deal With the Dentist

Potential impact on treatment plant Assuming 2.5 million gal/day flow No. Dentists Dental Mercury (lb/yr) Influent Impact (ng/L) Domestic Background (ng/L) Net Influent (ng/L) WWTP Removal Net Effluent (ng/L) ~5076~98% ► 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 ► Deal With the Dentist

Potential impact on treatment plant Again assuming 2.5 million gal/day flow No. Dentists Amalgam Separator Removal Dental Mercury (lb/yr) Influent Impact (ng/L) Domestic Background (ng/L) Net Influent (ng/L) WWTP Removal Net Effluent (ng/L) % ~5051.3~98% ► 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 ► Deal With the Dentist “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.”

► Perspective Justifiable concern over mercury in waterways –Air emissions need same, or greater, scrutiny as wastewater 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

For additional information: Jerald O. Thaler, P.E. Fishbeck, Thompson, Carr & Huber, Inc Country Club Drive, Suite B-25 Farmington Hills, MI ► Questions and Discussion