The Narragansett Bay Commission 

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# -2 t bL tVinct J . Mesolella

One Service Road Chairman Providence, Rhode Island 02905 Raymond J . Marshall, P .E

. 401 • 461 • 8848 Executive Director 401 • 461 • 6540 FA X 'I'I'Y (RI RELAY OPERATOR) 711 

## JAN 0 2 20 C8 http :/iwww .narrabay .com ~nsett B'~~ December 27, 200 7
Water Docke t Environmental Protection Agency Mailcode 4203 M 1200 Pennsylvania Avenue, NW Washington, DC 2046 0
RE : Docket ID No . EPA-HQ-OW-2006-0771

Dear Sir/Madam : The Narragansett Bay Commission (NBC) owns and operates the two largest Publicly Owned Wastewater Treatment Works (POTW) located in the State of Rhode Island . One POTW, the Field's Point WWTF is located in Providence and the other is located at Bucklin Point in East Providence
. The NBC has thoroughly reviewed the Preliminary 2008 Effluent Guidelines Program Plan an d would like to thank the USEPA for providing the oppo rtunity to comment on this impo rt ant plan
. Based upon our review, the NBC does not recommend that the EPA expend valuable resources to develop new federal catego ri cal regulations for indirect dischargers . The NBC, like other POTWs with approved Pretreatment Programs, has extensive knowledge and experi ence controlling the discharge of toxics from indust ri al and commercial sources . Technologically developed local limits, along with an enforceable sewer use ordinance, are all the tools that are necessary for the NBC's Pretreatment Program to protect our wastewater facilities, the receiving waters of Narragansett Bay, public health and the environment . The NBC would like to further comment on the Effluent Guideline proposed for controlling dental mercury . In 2003, the NBC developed a Best Management Practices document for the Man agement of Waste Dental Amalgam (BMP) and the NBC implemented a BMP Dental Program in 2004 . The NBC worked with the R .I . Dental Association to develop this program
. A copy of the BMP is attached to this letter for your information . The BMP provides facilities, including dental offices, dental clinics and hospitals, that have the potential to discharge mercury containing dental amalgam to the sewer system two options to control the discharge of mercury to the sewer system
. The first option allows the facility to install an amalgam separator that has a separation efficiency of 99% according to ISO 11143 standards . Under this option the permitted user is not required to routinely sample the waste stream . The second option requires the user to routinely sample their discharge and achieve compli an ce with the local mercury discharge limitation established to protect the treatment facility and the environment

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In addition to the two options, there are mandatory Best Management Practices that mus t be followed by this class of users . These include the following : ➢ installation of dental chair side traps and their maintenance, ➢ maintenance of vacuum pump filters , ➢ storage, management and disposal of scrap amalgam, ➢ use of only approved line cleaners , ➢ specific requirements for sinks located in operatories, ➢ annual cert ification submittal requirements , ➢ record keeping requirements, an d ➢ training of dental staff in waste m an agement and spill response . In addition the BMP document provides information about pollution prevention and hazardous waste management . All of the facilities in the NBC's two distri cts opted to install amalgam separators in lieu of performing routine effluent monito ri ng. These BMPs are w ri tten into Wastewater Discharge Permits issued to each facility performing dental operations . By implementing the BMP program, the NBC has seen a great reduction in the influent mercury loading to both NBC Wastewater Treatment plants . In fact within the first six months of implementing the program the NBC Field's Point plant realized an 18% influent mercury loading reduction and the Bucklin Point plant achieved a 23% reduction in mercury loading . The following table of annual influent loadings clearly demonstrates the success of the NBC Dental Mercury BMP Program : Year Field's Point (Ibs) Bucklin Point (Ibs) 2003 16 .0 6 .5 2004 13 .1 5 .4 2005 13 .3 5 .6 2006 10 .8 4 .5 Overall % Reduction 32 .5% 30 .8 % The NBC Dental Mercury Control BMP Program has been so successful that the Rhode Island Department of Environmental Management has implemented the NBC program as a mandatory requirement throughout the state . To summarize, the NBC believes that Publicly Owned Wastewater Treatment Works are effective at controlling the discharge of mercury to the sewer system from dental facilities and that imposing new or additional catego ri cal standards are not necessary for indirect dischargers controlled by approved Pretreatment Programs . Thank you for providing the Narragansett Bay Commission the opport unity to comment on the Preliminary 2008 Effluent Guidelines Program Plan . If you have any questions or need any additional information, please feel fr ee to contact me at 401-461-8848 ext . 470 . Sincerely,

Thomas P . Uv a Director of Planning, Policy & Regulation
Cc : Raymond J . Marshall, P .E . - NBC Kerry M . B ri tt - NB C Ch ri s Hornback - NACWA