Wambo Coal AEMR 2011-2012 - Peabody Energy

WAMBO HOMESTEAD
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B L A S T V I B R AT I O N V U L N E R A B I L I T Y S T U DY
1 INTRODUCTION
1.1 Wambo Homestead and blast vibrations
Wambo Homestead is a complex of early 19 th century buildings located on the Wambo Coal Mine site near Warkworth
in the NSW Hunter Valley. The building complex has been the subject of many studies over the years and is registered
under the NSW Heritage Act with State Significance. No further discussion of the many heritage aspects of these
buildings will be contained in this report.
Vibrations from mine blasting are a risk to the buildings and their condition has been monitored continually for many
years. A permanent ground vibration monitoring station is set up near the complex and the records from this station
are assessed continually. Bill Jordan & Associates has also been undertaking an annual assessment of the buildings to
determine if vibration damage has been caused; separate visits and assessments have also been carried out following
the few occasions when the monitor recording registers a value greater than 5 mm/s peak particle velocity (PPV).
1.2 Setting of limits
1.2.1 BLAST VIBRATION LIMITS BASIS
The following publications appear to form the basis for the setting of vibration limits in use at present:
• AS 2187.2—2006 (or particularly its predecessor, AS 2187.2—1979), “Explosives—Storage and
use, Part 2: Use of Explosives”,
• Australian and New Zealand Environment Council, “Technical basis for guidelines to minimise
annoyance due to blasting overpressure and ground vibration”, September 1990 (ANZEC 1990).
Since the existing limits were set, further publications have been issued which are relevant and likely to be considered
in any future approvals, in particular “Assessing Vibration: a technical guideline, Department of Environment and
Conservation NSW, February 2006 (DEC 2006).
Of particular note from all these publications is that the limits have all been based on human response to vibration,
not building response. For example, the ANZEC 1990 guideline states:
The recommended criteria apply only to the minimisation of annoyance and. discomfort arising
from blasting.
Similarly, the more recent DEC 2006 publication states:
This guideline presents preferred and maximum vibration values for use in assessing human
responses to vibration and provides recommendations for measurement and evaluation
techniques. It does not address motion sickness, occupational vibration, blasting vibration
effects or vibration-induced damage to buildings or structures.
AS 2187.2—2006 does address damage limits in the “Informative” appendix (i.e. does not form part of the Standard
as a “Normative” appendix does), Appendix J, but does not distinguish between normal buildings and sensitive or
heritage buildings. The previous edition (1979) suggested a PPV limit of 5 mm/s for heritage buildings, but without
any justification.
Overseas standards such as the United States (USBM) RI 8507, the British BS 7385–2 and German DIN 4150 have
some applicable limits. One of the key features in these standards, now recognized in AS 2187.2, is that the limits
are frequency dependent: in AS 2187.2—2006 the frequency dependent vibration limits from BS 7385–2 are given
in Figure J4.4.2.1 and those from (USBM) RI 8507 in Figure J4.4.2.2. Whilst heritage buildings are not dealt with
specifically in these standards, it is notable that the most stringent case in BS 7385–2 is for a PPV of 15 mm/s at
4 Hz, rising to 20 mm/s at 15 Hz and 50 mm/s at 40 Hz; the most stringent condition in (USBM) RI 8507 has similar
April 2012
Wambo Homestead
Vibration vulnerability