|
RTA
Demolition Dust Minimisation Procedures
By
Franki Lee, NSW Roads and Traffic Authority, franki_lee@rta.nsw.gov.au
Editor's
Note: On the basis of the first dot point below, you would expect
that cavity dust removal would be done as a matter of course, prior
to demolition - yet it isn't. Who has evidence that screens stop
cavity dust? What type of screens would?
The
following are the dust minimisation procedures used by RTA
contractors for demolition work:
- The contractor shall take all
necessary precautions to prevent the contamination of the
atmosphere, building and their surrounds by airborne fibres
and particulates.
- Prior to any demolition work
commencing the contractor is responsible for providing
temporary barrier/screens, as appropriate, to suppress the
effect of dust movement to adjacent occupied properties.
- Demolition of areas likely to
result in significant dust is not to be undertaken during
periods of strong winds.
- The contractor is to ensure
that dust generating materials are maintained in a moist
condition during demolition or loading activities.
- Material transported in open
trucks shall be covered to prevent the generation of dust.
- The tailgates of all vehicles
used to transport material from the demolition site shall be
securely fixed prior to loading.
- The burning of timber or
other combustible materials is prohibited at all times.
These
dust minimisation measures have been included in the Specification
for Demolition Work (Environmental Management Plan) used for
demolitions on the M5 East motorway and other motorways.
WorkSafe
Guidelines for Building Cavity Dust
By
Elizabeth O'Brien, National Coordinator, The LEAD Group Inc.
Following
from the last edition of LEAD Action News, I tried to research the
possible health effects of exposure to ceiling dust and other
building cavity dust, and to find out what, if any, guidelines could
be applied to handling the dust. The NOHSC (NATIONAL OCCUPATIONAL
HEALTH and SAFETY COMMISSION - previously WorkSafe) website at
http://www.worksafe.gov.au/ contains an overwhelming amount of
information on Air Toxics at Work. To piece together all the
relevant standards for working in building cavity dust, one would
have to, at the minimum, check out the following sections:-
AIRBORNE
PARTICULATES:
Building cavity dust
does not have an assigned exposure standard. The advice is, "it
should not be assumed that this indicates that these unlisted dusts
do not represent a hazard to health."
HAZARDOUS
SUBSTANCES: In
this section the exposure standards are given for about 26 of the
elements found to be in ceiling dust by Jeff Davis (see article on
page one of this newsletter), but mostly as compounds. The section
includes the following excerpts:
INDEPENDENT
EFFECTS: "Where
there is clear toxicological evidence to indicate that two or more
contaminants have totally distinct mechanisms of effect on the body,
then each substance may be separately evaluated against its
appropriate exposure standard."
ADDITIVE
EFFECTS: "When
the body is exposed to two or more contaminants, an additive effect
is obtained when contaminants have the same target organ or the same
mechanism of action. In this situation, the total effect upon the
body equals the sum of effects from the individual substances."
SYNERGISM
AND POTENTIATION: "Sometimes
the combined effect of multiple exposure is considerably greater
than the sum of the effects from the individual components. This
phenomenon can be one of synergism or potentiation. Synergism occurs
when both chemicals have an effect individually and a more than
additive effect when together. Potentiation is when one chemical has
an effect but the second chemical does not but enhances the effect
of the former chemical on combined exposure.
"Interaction
effects may also occur in connection with exposure to entirely
different environmental factors such as simultaneous exposure to
chemical agents and physical factors, such as light, heat and
noise... Smoking of tobacco is known to have a synergistic effect in
combination with, for example, inhaled particulates.
"At
present the understanding of interaction effects is incomplete. The
knowledge that such effects can occur is reason to maintain the
concentrations of individual substances as low as is practicable
under complex exposure conditions."
FIBRES:
since the ceiling cavity can contain various types of insulation
including asbestos insulation around hot water heaters, the
following excerpts are relevant:-
ASBESTOS: "The
average fibre concentration of the air breathed by a worker
throughout a working shift...should not exceed...0.1 fibres per mL
of air (TWA [time weighted average] Exposure Standard) [for] any
mixture of [the different types of] asbestos, or where the
composition is unknown."
SYNTHETIC
MINERAL FIBRES: "For
respirable fibres, the National Commission has adopted a TWA
exposure standard of 0.5 fibres per mL of air be applied to
synthetic mineral fibres (ceramic fibres, glass fibre and rock wool).
"For
non-respirable fibres, in situations where almost all the airborne
material is fibrous, a secondary, yet complementary, TWA exposure
standard of 2 mg/m3 (inspirable dust) is proposed."
PESTICIDES: If
exposure to pesticides is suspected, blood samples can be analysed
to determine the extent of exposure.
When
"building cavity dust" is an actual listed item in all
these government guidelines, the Australian Dust Removalists
Association will have had success!
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)]
| |
EPA
Inert Waste maximum
Total Concentration Threshold |
EPA
Solid Waste maximum
Total Concentration Threshold |
EPA
Industrial Waste maximum Total Concentration Threshold |
FLUE
DUST SAMPLE |
CEILING
CAVITY DUST SAMPLE |
Lead
(mg/kg) |
10 |
100 |
400 |
> 6434 |
> 1381 |
Chromium
(mg/kg) |
|
|
|
65 |
38 |
Chromium
(VI)* (mg/kg) |
10 |
100 |
400 |
|
|
Cadmium
(mg/kg) |
2 |
20 |
80 |
7 |
> 22 |
Nickel
(mg/kg) |
4 |
40 |
160 |
> 516 |
<
0.5 |
*
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 (5th 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. |
|
EPA Inert Waste maximum Specific Contaminant
Concentration |
EPA Solid Waste maximum Specific Contaminant
Concentration |
EPA Industrial Waste maximum Specific
Contaminant Concentration |
FLUE DUST SAMPLE |
CEILING CAVITY DUST SAMPLE |
Lead (mg/kg) |
1500 |
1500 |
6000 |
<
6434 |
1381 |
Nickel (mg/kg) |
1050 |
1050 |
4200 |
516 |
<
0.5 |
|
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:
- wall cavity dust from
a major harbour side residential re-development had a lead (total)
concentration of 10,000 mg/kg, and
- 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
|
Contents Previous Item
Next Item |
