Many acidified water samples are held in the EnRad Radiochemcistry laboratory, some of them of considerable age. According to an agreement reached with PowerWater, disposal of chemicals to the sink is acceptable, provided concentrations and volumes do not exceed a specified limit. The agreement with PowerWater should be consulted when any chemicals are to be disposed of and is located on SSDX at the location given below.
\Corporate Management\Property Management (including Environmental Management System)\Environmental Management Systems (EMS)\SSD Environmental Management System development 2005 onwards including sustainability reporting\Data Collection\EMS- Chemical waste for drains etimates.xls
The following volume limits for disposal of acidified water are recommended based on this agreement:
20 L of 2% Nitric acid disposed to sink in any 24 hour period
30 L of 0.5% Hydrochloric acid to sink in any 24 hour period
This represents a limit for total disposal of acidified water from the eriss site. To ensure this daily limit is not exceeded consultation with other laboratory managers must be sought before disposing of acidified water (including wash baths) in volumes larger than 5L.
When disposing of samples, other constituents of the sample must also be taken into consideration. Examples of additional constituents of relevance include metal and radionuclide concentrations. It is the responsibility of those directing sample disposal to ensure that waste is disposed of appropriately. The eriss radiation source control plan and agreement with PowerWater (indicated above) on SSDX can be used to identify acceptable limits of radionuclides for disposal to the sewer:
\OH & S\Safety Manuals\Radiation_Safety\Radiation_Source_Control_Plan\Versions\ RadSourceControlPlan_v10.doc
For limits on the disposal of metals in solution and other potential constituents of samples the PowerWater Trade Waste code (Power And Water Corporation 2004) should be consulted. If there is any uncertainty regarding limits for disposal or pre-treatment requirements the PowerWater Trade Waste Manager should be consulted for advice and clarification.
The EnRad Radiochemist is currently in the process of identifying and scheduling disposal of all water samples for which all required analyses have been performed. However, there are currently no default holding periods specified for non-commercial samples beyond which disposal is automatically scheduled. This can impede the scheduling of such disposal. As a starting point a sample should not be disposed of until all required analyses are completed, or the period in storage exceeds the maximum recommended holding time for reliable analysis. It is recommended that the default period should be one year in the absence of advice to the contrary on a given sample bottle. It must also be noted in this report that there is no clear or consistent procedure across eriss for ensuring samples are disposed of within appropriate timeframes. A broader eriss review of these procedures should be undertaken to ensure therse procedures are improved.
Prior to beginning sample disposal, the marble chip containing neutralisation sump outside the EnRad laboratory was tested and showed A pH of around 6–8 for water flowing out of the sump. This indicates that the sump has neustralised previous flushes of acid and that there is still at least some residual neutralising capacity present.
Also of importance in this process is the fact that the agreement with PowerWater has not been updated since the eriss laboratories were occupied in 2002. As such it is possible that there have been changes to the type and quantity of material that is being disposed of to the sewer by activities on the eriss site. It is also possible that the PAWA acceptance conditons for waste to sewer have changed. Additionally, it is not clear in the agreement whether laboratories other than those in EnRad can dispose of significant quantities of acid to their drains – ie without passing through a neutralisation sump.
It is recommended that pH testing of the sump outflow water continues on a regular basis (no more than 24 hours before and after any disposal events) until daily sample disposals to the maximum allowable limit are no longer required. Additional testing should be mandated on a 6 monthly basis to ensure the marble chip s are not depleted.
It is recommended that a holding period is specified for every sample that is received in future within the EnRad Laboratory. It is recommended that a default holding time of 6 months after final results have been reported be implemented immediately for all new samples, and currently held samples.
It is recommended that an audit of current practices for disposing of laboratory waste to the sewers is conducted for the eriss site. This should include all chemical types and quantities that are intended to be disposed of to the sewer. The information gathered in this audit should be used to update the ‘Chemical waste for drains estimates’ spreadsheet and assessed by a competent person to determine if changes need to be made to eriss’s agreement with PowerWater. Note that this may change the testing recommendation for the sump indicated above.
It is recommended that an audit of current practices for disposing of laboratory waste to the sewers is conducted for the eriss site. This should include all chemical types and quantities A review should be conducted to ensure that the disposal of chemicals to sewer by eriss is consistent with current best practice environmental management requirements.
3.3 Reactivity checks
An assessment of the potential for cross reactivity between chemicals (divided into solids liquids, flammables etc) is provided in the tables contained in Appendix 5. These tables identify the number of storage groups of compatible chemicals that are required. A storage group is defined as a group of chemicals of similar type (ie – solid, liquid, flammable etc) that can be stored together without risk of hazardous cross reaction. As a result of this assessment some modifications to current practice of chemical storage need to be implemented, as detailed below.
It is recommended that a small flammables cabinet is purchased specifically for the purpose of storing Acetic Acid, Acetone and Nitromethane.
It is recommended that a small corrosives cabinet is purchased for the storage of solid sodium hydroxide pellets.