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The following section provides an explanation and general overview of mercury waste disposal. All waste disposal activities should be approved by an Environmental, Health and Safety Officer or the person responsible for waste disposal. The MWRA prohibits the disposal of chemicals into the sewer system except aqueous solutions of non-toxic and non hazardous chemicals. The Massachusetts Department of Environmental Protection (DEP) prohibits the improper disposal of hazardous wastes. The following waste disposal guidelines were established to satisfy both the MWRA and the DEP regulation requirements.
Based on TCLP test data, the Massachusetts Hazardous Waste Regulations at 310 CMR 30.00 consider a concentration of waste with less than 200 ppb of mercury to be a non-regulated material (MA99). Non-regulated materials are exempt from all of the DEP's hazardous waste regulations and can be accepted by landfill for final disposal.
Wastestreams determined, from TCLP testing, to have mercury concentrations equal to or greater than 200 ppb are hazardous waste which are given the code number D009.
The MWRA has a more stringent limit for total mercury which is prohibited. As a matter of policy, however, at the present time the MWRA will not enforce the discharge limitation for wastewater discharges containing less than one ppb.
It is possible that significant mercury concentration will be found in infrastructure piping where old biomass is present. Powerwashing and trap cleaning operations typically yield wastewater mercury concentrations in the 1 to 200 ppb range. This means that most infrastructure cleaning operations will require the wastewater to be collected and, in most instances, to be handled as a non-hazardous waste. The determination of whether a waste material is hazardous waste or non-regulated material should be made based on TCLP analytical testing. It is possible to use generator knowledge to assume a waste is a hazardous waste if it is based on accurate and available information regarding similar wastestreams. Some of this experience and information could be previously analyzed wastewater samples, chemical vender material safety data sheets (MSDS) and testing. Due to potential liability, extreme care should be taken when deciding that a wastestream is not a hazardous waste without the benefit of analytical testing.
Analytical testing is the most conservative method for waste characterization. Although this is the best method for determining if a waste is regulated, it can be very expensive when the generator has no knowledge of the waste. This means that several different analytical test would be required to ensure that all potential waste characteristics have been evaluated.
The combination of generator knowledge and analytical testing are the most common procedures used for hazardous waste determination. Using generator knowledge of the waste enables a generator to eliminate a majority of analytical testing for materials that are known not to be present.
After the waste has been collected and a determination made about the waste, one of the following methods of disposal may occur:
Discharge to the MWRA
If it is determined that the collected wastewater contains mercury below one ppb and that all other pollutant concentrations are below discharge limits, this waste can be discharged to the sewer only after written approval from the MWRA has been obtained. The MWRA requires a notification prior to all non-typical wastewater discharges.
Off-Site Disposal as Non-Regulated Material (MA99)
If the waste contains mercury at a concentration greater than 1 ppb, but less than 200 ppb, it is most likely a non-regulated material under the Hazardous Waste Regulations 310 CMR 30.00. Although non-regulated, the mercury concentration is above the MWRA's discharge limit and must be disposed off-site.
Prior to transporting a waste material to a licensed waste disposal facility the material usually will require pre-approval. The pre-approval process is a requirement of most licensed disposal facility and typically includes analytical testing and generator knowledge of the waste.
It is important that each waste shipment have all the same characteristics as initially approved by the licensed disposal facility. If the original waste approval was for powerwashing with water only and the next time powerwashing is performed but now with bleach and water, a new approval for disposal may be required. The addition of the bleach has now possibly changed the characteristics of the waste.
Off-Site Disposal as Regulated Material
Wastes that contain mercury concentrations equal to or greater than 200 ppb are characteristic hazardous wastes (D009). Regulations governing the handling and storage of hazardous waste in Massachusetts are located at 310 CMR 30.00.
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