Figure 2.1 pH Adjustment System
Source: Commonwealth of Massachusetts Fuel Gas and Plumbing Codes, 248 CMR 1.00 - 7.00, pg. 84
In Massachusetts, "Special Waste" includes, but is not limited to, organisms containing recombinant DNA molecules, chemicals, nuclear, radioactive, acids, alkalis, perchloric solvents and other such wastes that could be considered detrimental to the public sewer system and which do not comply with limitations established by the Publicly Owned Treatment Works such as the MWRA.
The design, methods, materials, type of neutralization, testing, and inspections required for "Special Waste" piping systems serving laboratories and industrial activities are governed under 248 CMR 2.13 of the Massachusetts State Plumbing Code (12/1/93).
The code establishes the guidelines for the proper installation methods and materials selection for "Special Waste" piping systems but not for the way it may be used after it is installed or what "chemicals" may be disposed into it on a daily basis.
Constant changes in chemical technology, the rearranging of existing laboratory spaces, and the lack of versatility in piping systems have created concerns relative to the safety and operations of "Special Waste" piping systems. Most recently, the greatest concern centers on the impact created by historical discharges of elevated amounts of mercury into these systems. Although the reduction of the mercury point source from existing waste streams will address most, if not all, of the non-compliance concerns, there is still the ongoing issue of biomass absorption of mercury within the piping system itself.
In particular, the following design guidelines are meant to focus on the biomass removal from piping systems. However, it must be noted that these guidelines should be followed when any type of "Special Waste" is introduced into a dedicated piping system designed specifically for the conveyance of special wastes.
The following regulatory guidelines have used 248 CMR 2.13 - Piping and Treatment of Special Wastes (12/1/93), as the primary basis for the design protocol considerations:
All plans and specifications for "Special Waste" piping and pretreatment systems shall be prepared by a Registered Professional Engineer for submission to the local Plumbing Inspector, MWRA, DEP or other authorities for their review and approval. Permits are applied for on the basis of the design and the inspections of the installed "Special Waste" piping and pretreatment systems must be made by the engineer during construction.
All "Special Wastes" must be conveyed in a separate waste and vent piping system. These systems are to be constructed of approved code materials. A list of these materials and installation requirements are located in 248 CMR 2.13 (12/1/93).
The Owner shall provide a notarized letter stating what materials are to be disposed of into the piping system.
All designs must conform with the intent of the regulations. Alternate design of a system, materials and/or "Special Waste" termination point shall be considered ONLY where evidence is presented that certain standards cannot be reasonably complied with. The plan for such a proposed alternate system shall specifically be submitted to the local Plumbing Inspector for review and approval.
Piping materials and equipment such as pumps, pits, etc., shall be constructed of materials chemically resistant and thermally compatible with the liquids being disposed or pumped.
Great care must be taken in the selection of system materials in order to be compliant, technically compatible and safe to use without the danger of leakage and spills. Non-compatible applications such as hydrofluoric acid with glass piping, high-temperature waste streams with thermo-plastic piping and non-pressure rated pipe and fittings on special waste pump discharge lines must be addressed. Conversely, "Special Waste" piping systems cannot be used for the conveyance of sanitary type wastes.
Neutralizing sumps or tanks shall be used for the pretreatment of wastewaters containing dilute acids and alkalis from laboratory sinks. These sumps are not allowed to adjust the pH for wastewater generated by biomedical laboratories. These sumps similarly cannot be used in facilities discharging significant quantities of organic materials into the "Special Waste" System or the biomass which is found will coat the marble chips rendering the media useless. The different types of neutralizing materials, and approved materials of construction and sizing are described in 248 CMR 2.13 (12/1/93).
Each reactor vessel is to be fitted with an agitator capable of operating at all times when waste flows occur, a pH monitoring system for operation of acid/alkali neutralizing media to maintain a tank pH level of between 5.5 and 10.5, as required by the MWRA's Sewer Use Rules and Regulation 360 CMR 10.023 (7/2/93) and related controls. Prior to using any neutralizing media it should be analyzed for mercury content. Several institutions found that lower grade neutralizing media contained high concentrations of mercury. This finding forced the institutions to use a higher quality reagent grade chemical.
The discharge piping from the reactor vessels shall be fitted with a trap, pH monitor and recording device, a sampling port for Regulatory Agency testing, and a flow meter and recording device, as required.
The MWRA requires that all facilities with industrial wastewater discharges of 25,000 gallons per day or greater, or subject to EPA categorical limits with wastewater discharges of 1,000 gallons per day or greater, monitor flow during compliance sampling. The recent installation of flow monitoring devices in several institutions has documented that these institutions had been significantly over estimating their flow rates. Since the MWRA bases permitting and sampling fees on flow, an institution may be doing unnecessary sampling and reporting if flow estimates are not accurate. The additional sampling and permitting fees may be avoided if actual flow rates are obtained via flow monitoring devices. In most cases these devices can pay for themselves from the reduced MWRA sampling and reporting fees alone.
Systems adjusting pH are to be accessible for maintenance, repair,
operation, and
Figure 2.1 pH Adjustment System
Source: Commonwealth of Massachusetts Fuel Gas and Plumbing Codes,
248 CMR 1.00 - 7.00, pg. 84
Figure 2.2 Special Waste Battery System and Vent Piping
Source: Commonwealth of Massachusetts Fuel Gas and Plumbing Codes,
248 CMR 1.00 - 7.00, pg. 140
sampling procedures. The operation and maintenance requirements of these pH adjustment systems are detailed in 314 CMR 12.00, Division of Water Pollution Control regulations. In addition, these wastewater pretreatment systems are required to be operated by certified wastewater pretreatment operators. Certification requirements for wastewater pretreatment operators are detailed in 257 CMR 2.00, Board of Certification of Wastewater Treatment Facilities regulations.
The MWRA prefers that institutions use open channel type flow devices whenever possible and that these devices be compatible with their samplers for flow monitoring connections. The recommended open channel flow device for high flow conditions is the Parshall flume and, for low flow conditions, the Palmer-Bowlus flume is preferred.
It is not always possible to install open channel flow devices because of space limitations. In this situation, the use of an in-line velocity meter to monitor flow is acceptable.
Whichever device is selected, it is very important that these devices be compatible with the MWRA's sampling equipment. The MWRA's samplers are capable of receiving direct and indirect signals from flow monitoring devices. The specific signal requirements are presented in communication from the MWRA to Beth Israel which is located in Appendix E.
 |
 |
 |
| Previous | Contents | Next |