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Businesses that generate waste in Washington state are subject to the Washington State Dangerous Waste Regulations, Chapter 173-303, Washington Administrative Code (WAC), and must designate their waste streams to determine if their waste exceeds dangerous waste limits.
Because of the threat to human health and the environment posed by mercury and silver, dental offices are also subject to all of the dangerous waste requirements of the inspection requirements of Chapter 70.105 Hazardous Waste Management.
A dental office that places or removes mercury amalgam fillings without an amalgam separator installed may exceed the dangerous waste designation limit for mercury (0.2 mg/L or ppm) for its waste water. To help prevent the discharge of mercury or other dangerous waste elements into the environment, the dental office have three options. They may:
Contact your local government representatives and your waste water treatment plant to for additional requirements. For an example of the type of additional requirements that may be necessary go to http://dnr.metrokc.gov/wlr/indwaste/dentalfactsheet.pdf. There you will find information on King County’s dental program requirements.
You must collect all vacuum system waste water generated during the hours of operation in a standard work week for your office. It is important to obtain a representative sample of the waste stream that includes a typical amount of mercury work. Selecting a week which skews the data either toward higher or lower concentrations of mercury is inappropriate. If there is indication of such practices, Ecology reserves the right to collect its own samples for analysis or require additional analyses by the generator.
Ecology decided to use the same system required by King County and the City of San Francisco for the collection of dental waste water. Informally called a “Berglund device” or “MCES(1) device,” a summary of the device follows below. For more information go to:
King County: http://dnr.metrokc.gov/wlr/indwaste/dentists.htm
San Francisco: http://sfwater.org/Files/Forms/Wastewater_Monitoring_Sampling_and_Analysis_Methodology.pdf (Link removed 09/01/06)
Note: King County and San Francisco are collecting samples for different reasons and their guidance will deviate from Ecology’s at times. It is important to follow the Ecology guidance as this is the standard to which Ecology will hold you should field staff conduct a compliance inspection of your office.
A Berglund device is a 5 gallon (20 liter) polypropylene carboy which has been adapted using PVC piping, to collect waste from dental chairs. It is plumbed into the vacuum line just prior to the vacuum pump and after the amalgam waste water treatment unit (if previously installed) indicated in this diagram:
The placement of the device assures the collection of all waste coming from the dental chairs while avoiding other waste streams generated in the office (sinks, sanitary sewers, etc.). It also avoids collecting any water that may be required for operation of the vacuum pump. If an office has more than one vacuum pump system, the waste from all pumps must be collected by adding a waste collector on each waste stream or some other process.
Once the device is installed, it allows the replacement of the plastic carboy when full(2). Each carboy is then shipped to a laboratory for analysis using standard EPA methods (SW-846). A list of accredited laboratories is available on Ecology’s Web site at http://ecy.wa.gov/programs/eap/labs/srchmain.htm
The laboratory is required to take a representative sample from each carboy for analysis. Protective procedures should be used while handling the samples to decrease exposures to possible metal and potential biological contaminants. The following analyses are requested for each carboy:
⇒Total metals via SW-846 8000/7000 Series
The laboratory will report the concentrations of metals as mg/L (milligrams per liter), μg/L (micrograms per liter), or ppm (parts per million). If the laboratory reports the data in μg/L, the value must be divided by 1,000 (to convert from μg/L to mg/L) before the comparison can be made. Note: mg/L is equivalent to ppm so no conversion is necessary.
If the amount of total Mercury in the waste stream exceeds 0.2 mg/L (or ppm) additional testing may be necessary. Whether or not additional testing is needed depends on the percentage (%) of solids in your waste stream. The laboratory can run the following analysis for percentage of solids:
⇒Percentage of solids (the initial step in Method 1311 or equivalent)
If the percentage of solids is greater than 0.5% of the sample by weight, it is necessary to evaluate the test results to determine if an additional extraction and analysis are needed. If the mercury concentrations are greater than 4.0 mg/L (ppm) or the silver concentration is greater than 100.0 mg/L (ppm), it is necessary to designate the waste as required by the Dangerous Waste Regulations. Specifically, you must request a Sample prep via Method 1311(3) and a RCRA metals analysis via SW-846 8000/7000 Series Methods.
The two hazardous metals of most concern for dental offices are mercury and silver used in amalgams. Silver is also used in dental offices that develop their own X-rays. The final analytical results may be compared directly to the 0.2 mg/L (ppm) and 5.0 mg/L (ppm) dangerous waste limits for mercury and silver, respectively.
If you collected more than one carboy, the results from each carboy must be compared to these limits. If 50% or more of your carboys fail any of these limits, your waste water designates as a dangerous waste.
Ecology understands the above process may be confusing. To help clarify the issue, a decision tree of the process you should follow is provided in Appendix 1. Although the decision tree shows two analyses for metals, this process was selected to minimize the amount of sampling and analysis needed to meet the needs of Ecology and local authorities such as your waste water treatment plant.
Based on what Ecology knows of the waste stream, it is unlikely that the second analysis will be needed. However, for those waste streams that have a high amount of solids, Washington’s Dangerous Waste Regulations require the second analysis for designation. The first analysis will still be useful to your local authorities. Note: it is still possible the waste stream is not a dangerous waste even though it failed the first test.
Once the analyses have been completed, no further analyses are necessary by Ecology unless the waste stream changes in any way or unless specifically requested(4). Changes to the waste stream can include but are not limited to:
The designation information is kept on file at the dental office and made available upon request to any Ecology, County or City representative who visits. Do not submit this information to Ecology, unless requested. If the information found in this documentation proves to be incorrect, Ecology may evaluate its options including the possibility of a penalty and fine as defined under RCW 70.150.080(5).
Because of the threat to human health and the environment posed by mercury and silver, dental offices are subject to all of the dangerous waste requirements of WAC 173-303 (Washington’s Dangerous Waste Regulations) and the inspection requirements of Chapter 70.105 Hazardous Waste Management which grants Ecology the authority to ‘Enter at reasonable times establishments regulated under this section for the purposes of inspection, mentoring, and sampling’ as identified in RCW 70.405.130. Ecology has defined “reasonable times” to be during normal business working hours. Based upon the review of the information provided, Ecology may require sampling to verify the concentration of mercury and silver contamination in the waste stream.
Ecology personnel are available to assist you with any questions on this topic. Please contact your local regional office:
2. Depending on the amount of waste generated, more than one carboy may be necessary to collect all the waste during the sample period.
3 This method is the TCLP (toxicity characteristic leaching procedure) extraction required for waste designation. It is only needed if your waste stream has a percentage of solids concentration greater than 0.5%.
4 Local agencies and your waste water treatment plant may require additional sampling over time to verify that you continue to meet their discharge limits. Contact your local representatives for information on their requirements.
5 Revised Code of Washington (RCW) 70.150.080 Violations-Civil Penalties reads: Every person who fails to comply with any provision of this chapter or of the rules adopted thereunder shall be subjected to a penalty in an amount not more than ten thousand dollars per day for every such violation. Each and every such violation shall be separate and distinct offense.
To construct a Berglund device, the following items must be procured and assembled (total assembly time, approximately 1 day):
The information in this appendix was borrowed from the document Waste Water Sampling and Analysis by the San Francisco Public Utilities Commission, Bureau of Environmental Regulation and Management. The complete text can be found at: (http://sfwater.org/detail.cfm/MC_ID/4/MSC_ID/85/MTO_ID/NULL/C_ID/1656#
The information below may deviate slightly from that provided by San Francisco as the reasons for sampling are different. This guidance, however, was written specifically to address the needs for dangerous waste sampling and should be followed as written. If you have any questions, contact your local Ecology office for advice.
Waste Water Sampling Device Specifications
Specialized sampling equipment is required for establishing compliance under Option 3. Because of the heterogeneity of dental amalgam in wastewater, Ecology requires that all vacuum discharge wastewater must be collected. This ensures representative sampling.
A modified 20 L sample collection bottle and manifold (“Berglund device,” or “MCES device”) has been adopted for use as the approved Ecology protocol for dental waste water sample collection. The Berglund device is based on a research program conducted by Metropolitan Council Environmental Services (MCES; St. Paul, MN)(6).
The Berglund device is made from a 20 L (5 gallon) vacuum-rated polypropylene (Nalgene®) carboy fitted with Schedule 80 bulkhead fittings, flexible 1” PVC, standard rigid 1” PVC, and unions, valves, tees, and elbows as shown in the figures below.
Figure 1: Berglund device in the “sample collection” mode (bypass arm closed).
The manifold is supported by standard U-bolts and brackets, mounted on a 3/8” plywood stand. The stand, manifold, and modified carboy are placed in a 32 quart household storage tray to protect against spills.
Glued fittings are used (in preference to threaded fittings) wherever possible to minimize loss of particles. A segment of clear PVC may be used on the manifold bypass arm or outlet to show when an overflow condition exists.
Sample collection requires the use of several modified carboys. Individual sample collection carboys are switched out whenever they are full.
To switch carboys, follow the steps detailed below:
Figure 2: Switch valves to “bypass mode.” The bypass arm (on top) is opened and the sample collection arms closed to allow removal or replacement of the sample collection bottle. Vacuum service to the dental office continues uninterrupted. Break vacuum to the carboy by loosening the carboy lid.
Figure 3: Detach the unions joining the sample collection arms.
Figure 4: Cap the open sample collection arms to prevent contamination. Tighten the carboy lid, if it has been loosened.
Figure 5: Set the sealed carboy aside and put an empty carboy in its place. Reattach the unions as shown.
Figure 6: Reset the sample collection valves to the open position. Note that the bypass valve (on top) also remains open at this stage.
Figure 7: Close the bypass valve to resume normal sample collection.
The carboys collected are transported to a State certified laboratory for special sample handling and analysis.
Copyright © Washington State Department of Ecology. See http://www.ecy.wa.gov/copyright.html .
Copyright © Washington State Department of Ecology. See http://www.ecy.wa.gov/copyright.html.
