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May 2001

Greetings from the President...
Mercury TMDL Workshop Shares Latest News
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Greetings from the President...

by Teresa Herrera

Spring is here which is the time for new beginnings and growth.  As so many of us are caught up in the frantic pace of life, this is a good opportunity to stop, take a deep breath, look around, and appreciate the signs of life all around us.  The greenness of the hills, the blossoming flowers, the birds chirping happily away.

Something to be Proud of…

The Bay Section is also experiencing growth and renewed energy and vitality.  I am pleased to look around at our membership and see so many dedicated people volunteering their time to this organization.  I recently attended a Northern Regional Committee meeting in Sacramento where representatives from all the northern local sections were in attendance.  Just in this meeting alone, the SFBS had the strongest showing of attendees.  One of the exercises we went through was to figure out how many members in each section were “active in furthering the mission of CWEA”.  The SFBS group counted 53 people who play an active role in the CWEA!  The other sections were amazed at this number, as most of them could boast eight to ten active volunteers.

We here in the Bay Section have made this Section one that all other sections look to as a model.  Our committee structure, our volunteer pool, our success in carrying out the mission of CWEA, and the fun that we have in doing all this makes us a section that we should be proud of.  Let me say that I am extremely proud to be a part of the San Francisco Bay Section.


Your Bay Section Board of Directors has recently voted to subsidize a portion of our monthly dinner meeting costs.  What this means to you is that the cost of all our dinner meetings (with the exception of our Awards Banquet) will not be more than $25.  It is becoming increasingly difficult to find venues that charge less than this amount.  At the same time, we recognize that many of our members don’t get reimbursed by their employers for attending dinner meetings.  So, as a way to keep these meetings affordable and allow the maximum amount of people the opportunity to network and learn from a speaker, we decided to subsidize our dinner meeting costs.

With that said, I hope to see many of you at this month’s meeting.  It will focus on the winner of the Section’s Plant of the Year Award, Central Contra Costs Sanitary District.  Please refer to the flyer in this newsletter for detailed information about the meeting.

Until next month, remember to slow down, even stop, and take the time to appreciate all the beauty that this season brings.  Take care and be safe.

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Mercury TMDL Workshop Shares Latest News

By Bill Ellgas of East Bay Municipal Utility District

On January 17, 2001 the Lab Committees for Bay Area Dischargers Association (BADA) and the SF Bay and Santa Clara Valley Sections of the California Water Environment Association (CWEA) sponsored a half-day workshop in San Jose on the SF Bay’s mercury TMDL.  The workshop’s purpose was to disseminate information on mercury collected the year prior to and following the SF Bay Regional Water Quality Control Board’s letter requiring dischargers to begin using EPA Method 1631 for mercury analysis in treated effluents to gather accurate data as part of the mercury TMDL development process.  Four presentations were given to a group of nearly fifty.

The workshop began with a presentation from Peter Halpin, Caltest Analytical Laboratory, entitled, “A Review and Discussion of the Ultra Trace Total Mercury Method 1631.”  Mr. Halpin summarized the sampling (EPA 1669) and analytical (EPA 1631) protocols, and reviewed Caltest’s methods development and facilities changes made prior to 1631 certification.  He also discussed instrumentation, analysis notes to maximize precision and accuracy and minimize contamination, and Caltest’s experiences since becoming certified.  Mr. Halpin concluded that an autosampler can be reliably used for 1631 lieu of manual bubblers, 1631 criteria can be met without a class 100 clean room but he recommends its consideration, and industrial discharge and influent samples must be diluted or analyzed by the traditional method, EPA 245.1.

The second presentation, “A Comparison of 1999 and 2000 POTW Mercury Data, Methods & Special Studies,” was given by William Ellgas, East Bay Municipal Utility District.  Mr. Ellgas compiled and analyzed the mercury data from 17 Bay Area POTWs with average daily flows ranging from 2 to 126 MGD.  The data were generated by both EPA methods 245.1 and 1631, and collected between January 1, 1999 and December 31, 2000 from influent, effluent and special QC study samples.  The combined effluent flow of 505 MGD from the agencies surveyed represents 83% of the total POTW and Industry discharge to the San Francisco Bay.  Though acknowledged as a minor contribution to mercury levels in the Bay, the RWQCB’s January 24, 2000 draft mercury TMDL proposed a Bay wide mass limit for POTWs and Industry of 50 kg/year (twice the current flow of 600 MGD x a concentration goal of 25 ng/L). 

Data presented at the workshop compared EPA 1669 sampling protocols to “normal” sampling procedures to determine any differences between the two approaches, influent to effluent concentrations to calculate POTW mercury removal efficiency, and pre-2000 (245.1) to post-2000 (1631) data to calculate total mass loading using each analytical method.  The dataset consisted of 614 influent and 593 effluent samples analyzed by EPA 245.1, and 90 influent and 526 effluent samples analyzed by EPA 1631.  The following observations were reported: 

  • POTW laboratory QC studies showed that no measurable contamination difference was observed when “normal” sampling was compared against the ultra-clean, EPA 1669 sampling protocol.  However, reductions were seen when sampling containers and equipment were scrupulously cleaned and sample lines regularly replaced.

  • EPA 1631 appears not to be a good method for POTW influent samples when concentrations of >100 ng/L are present (supporting Mr. Halpin’s conclusion above).

  • With an influent to effluent treatment efficiency of >90%, secondary wastewater treatment is a highly effective means for removing mercury. Using a mix of data (predominately 245.1 with some1631) from the 1999 dataset, the total mercury mass from all Bay POTW and Industry effluents was calculated to be 22.2 kg/year (extrapolated from 18.7 kg/year).  Using only the 1631 data generated in 2000, the total mercury mass discharged for all POTW and Industrial dischargers was calculated to be 11 kg/year (extrapolated from 9.3 kg/year), one-fifth the proposed TMDL mass limit of 50 kg/year, and half the value obtained using 245.1 data.

The third presentation of the day given by Guy Kumar, San Francisco Public Utilities Commission, “Atmospheric Mercury Sampling and Data Review,” focused on the SF Bay Regional Monitoring Program (RMP) pilot study on atmospheric deposition and the data it generated.  Mr. Kumar discussed the scope of the pilot study, the methodology and instrumentation used, and the data it generated.  Atmospheric deposition is divided into two categories:  1. Wet and dry Direct, that which is deposited directly into the Bay at the air/water-surface interface, and 2. Indirect, that which is deposited on the watershed and washed into the Bay during rainfall events or by other means.  Over the course of the study, mercury concentrations appeared fairly constant at around 2000 pg/m3 in ambient air taken at the three (North, Central and South Bay) locations.  Values were seen as high as 4100 pg/m3 and as low as 1500 pg/m3.  Using the concentration information and the known surface area of the three Bay sectors, the total mercury mass loading from direct air deposition for the entire Bay is estimated at 20.3 kg/year, 8.4 and 8.5 kg/year in the North and South Bays respectively, and 3.6 kg/year in the Central Bay.  A similar approach used for indirect air deposition produced an estimated total mercury mass loading of 41.1 kg/year.

The final presentation of the day, “Improving the Haystack by Regulating the Needles; Mercury in Wastewater and Watershed-scale Process” was given by Dr. Khalil Abu-Saba, California Regional Water Quality Control Board, San Francisco Bay Region.  The range of issues Dr. Abu-Saba discussed from his “Big Picture” perspective included:

  • The Bottom Line – A proposed mass limit of 50 kg Bay wide for all wastewater with concentration goals as an annual average of 0.025 ug/L for deep water dischargers; 0.015 ug/L for shallow water dischargers; and 0.007 ug/L for the lower South Bay.  Compliance is proposed to be regulated by mass not concentration.

  • Mercury concentrations in sediment are a linear function of % fines ranging from 0.0 ug/L in sand to 0.4 ug/L in clay with 100% fines (values up to 1.1 ug/L were found).

  • Mercury concentrations in water are a linear function of suspended sediments.

  • “The Fly in the Ointment” – Methylation of mercury is considered to be the real problem; methylmercury is the form that bioaccumulates and can be magnified up to ten million times at the top of the food chain.

  • Some information on the TMDL timeline: by 2004 adopting control measures in the Basin Plan; 2004+ adopting criteria for methylmercury and mercury in fish

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Last updated: May 04, 2005.