Classification of Building Cavity Dust for Waste Disposal

By Elizabeth O'Brien, National Coordinator, The LEAD Group Inc.

Extract of Report of Multi-element Analysis of Flue Dust and Ceiling Cavity Dust

[NB mg/kg = milligrams per kilogram, which is the same as parts per million (ppm) or micrograms per gram (µg/g)]

* These limits apply to chromium in the +6 oxidation state only. "Chromium (0 and III oxidation states) have deliberately not been listed in this table [Table A3] and need not be tested for" according to the EPA guidelines.

The EPA Concentrations listed in the above table are taken from Table A3: Contaminant threshold values for waste classification of non-liquid wastes without doing the leaching test on pp 64-65 of Environmental Guidelines: Assessment, Classification and Management of Liquid and Non-Liquid Wastes, (May 1999) by NSW EPA. The bolded figures are where the threshold is exceeded by one of the sample results - the particular sample result is indicated by an arrow.

The above results - for a flue dust sample from a coal gas burner that had a flue vented into the ceiling cavity of a house, and the ceiling dust from that cavity are taken from Report of Analysis of Flue Dust and Ceiling Cavity Dust (5^th February 1998), published in LEAD Action News vol7 no2.

According to the EPA guidelines on classification of waste, the ceiling dust and flue dust analysed in the table above would be classified as Solid Waste because the dust was "Waste contaminated with lead from residential premises..."

If however, the dust had been taken from a commercial building, church, library, Early Childhood Health Centre (ECHC), etc, the person responsible for the dust would need to ensure that the dust was analysed (total concentration) for a number of contaminants. If the results showed the same levels of contaminants as listed above:-

on the basis of its cadmium content, the ceiling dust would initially be given a provisional classification as industrial waste, but, classification is not actually possible without further testing because the lead concentration exceeds the maximum for industrial waste

the flue dust would not be given a provisional classification because the nickel and lead content exceed the maximum for industrial waste.

Both types of dust waste would then require classification using leachable concentration (TCLP) test - this costs up to $800 for one element, or $300 each if 4 elements are tested. To my knowledge, there are no results of TCLP tests for lead or any other heavy metal in building cavity dust waste and this lack of testing is of concern, considering the tonnes of commercial and industrial building cavity dust that are released during building work or demolition and moved around our cities every day.

Again, in the hypothetical case that this dust came from a commercial building and the results showed the same levels of contaminants as listed above:-

• regardless of the lack of a TCLP result the flue dust would be given a provisional classification as hazardous waste on the basis of its lead content; (since the maximum Specific Contaminant Concentration (SCC) - Industrial Waste - has been exceeded)

• due to the lack of a TCLP result the flue dust cannot be given a provisional classification on the basis of its nickel content, though the classification as hazardous waste on the basis of the lead content is the highest category of waste that can be assigned anyway.

• due to the lack of a TCLP result the ceiling dust cannot be given a provisional classification on the basis of its lead content.

This hypothetical situation leading to an inability to classify the ceiling dust is a very good argument for TCLP testing of ceiling dust being carried out. Also, to my knowledge, no samples of ceiling dust have ever been assessed for the total concentration of pesticides. If the total concentration of a pesticide listed in EPA's waste guidelines Table A7 exceeds one milligram per kilogram, then the dust would be classified as a scheduled chemical waste. The disposal of scheduled chemical wastes is dealt with in Scheduled Wastes Chemical Control Order 1994, under the Environmentally Hazardous Chemicals Act 1985.

Two other documented examples of building cavity dust were also reported in LEAD Action News v7 n2. They were:

1. wall cavity dust from a major harbour side residential re-development had a lead (total) concentration of 10,000 mg/kg, and

2. ceiling cavity dust from an Early Childhood Health Centre (ECHC) in inner Sydney had a lead (total) concentration of 20,000 mg/kg.

My understanding of the EPA's waste guidelines is that both these dust wastes should have been provisionally classified as hazardous waste. I hazard a guess that neither of them was treated as such.

The ADRA Development Committee calls on the NSW EPA to do TCLP testing where appropriate, as well as total concentration testing for all the contaminants that no-one has tested for in building cavity dust (such as pesticides and other organic compounds, asbestos and other fibres).

Wastes which exceed the TCLP maximum value for Industrial Waste and / or the total specific contaminant concentration, need to have the contaminant immobilised and the immobilisation must be approved by the EPA. Without EPA approval of immobilisation, the waste is classified as hazardous. Hazardous waste is no longer permitted to go to landfill and must be stored or treated appropriately. If treated, it must again be classified before disposal. Since no building cavity dust waste to my knowledge has ever been correctly classified as hazardous waste, I am not aware of any approved immobilisation process for building cavity dust. Only one hazardous waste facility with a licence to accept building cavity dust has come to my attention - the ARA smelter at Alexandria has a hazardous waste facility licence and recycles the lead out of building cavity dust. As for what happens to the other contaminants in cavity dust, that is anyone's guess.

One ceiling dust contractor commented - "If ceiling dust was classified as hazardous waste [or even as industrial waste], people would treat it properly. Knowing that if the dust comes from a residence, childcare centre or educational institution it can be put in the rubbish bin for council to pick up, means no one takes it seriously.