8.1
In
accordance with the updated EM&A Manual, baseline condition survey and
baseline vibration impact assessment shall be conducted for identified built heritage
prior to the commencement of construction works. Baseline condition survey and
baseline vibration impact assessment shall be conducted by a qualified building
surveyor or qualified structural engineer to define the vibration limit (a
vibration limit at 7.5mm/s and 15mm/s could be adopted for graded
historical buildings and historical
buildings, respectively) and to evaluate if construction vibration monitoring
and structural strengthening measures are required during construction phase to
ensure the construction performance meets with the vibration standard stated in
the EIA report.
8.2
According
to the condition survey report from cultural heritage condition survey for Fanling Bypass Eastern Section under EP-473/2013/A,
vibration monitoring plan was proposed for the surveyed cultural heritage based
on the Buildings Department’s Practice Note (PNAP APP-137). This section
presents the results of built heritage monitoring performed by the Contractor
according to the proposed monitoring plan in baseline condition survey report. Appendix B shows the Limit Levels for
the monitoring works.
8.3
In
the reporting month, construction vibration monitoring was conducted for built heritage feature at FL36 when pile driving
operation was conducted within assessment area of construction works. The
location of the construction vibration monitoring stations was summarised in Table
8.1 and shown in Appendix H.
Table 8.1 Location of Construction Vibration
Monitoring
|
EP. No |
Contract No. |
Monitoring Station (s) |
Nature of Cultural Heritage |
Location (s) |
|
EP-473/2013/A |
ND/2019/05 |
FL36 |
Shrines |
Opposite to Lincoln Centre, adjoin the Ma Wat
River, slightly on the uphill side |
Monitoring Parameters and Frequency
8.4
Table 8.2 summarises
the vibration monitoring plan for surveyed cultural heritage under the Works
Contracts. Vibration monitoring was conducted for surveyed built heritage when
pile driving operation were conducted within the assessment area of
construction works.
Table 8.2 Vibration Monitoring Plan
|
EP. No |
Contract No. |
Monitoring Station (s) |
Distance with Construction Works |
Monitoring Plan |
|
EP-473/2013/A |
ND/2019/05 |
FL36 |
Within 50m |
Daily assessment is required |
|
Within 75m |
Bi-daily assessment is required |
|||
|
Within 100m |
Weekly assessment is required |
Remarks:
[1] Baseline condition survey was
conducted for built heritage features at HFL05, FL02, FL04, FL24, FL27 and FL36
under ND/2019/05 for EP-473/2013/A. As HFL05, FL02, FL04, FL24 and FL27 were
not within the assessment area of the related construction work, no
construction vibration monitoring was conducted for the built heritage in the
reporting month.
8.5
The
construction vibration monitoring was conducted throughout each event of the
pile driving operation on a daily basis. The effect of ground-borne vibration
from piling works on the surveyed built heritage was assessed by the maximum
peak particle velocity (ppv), which was obtained from
the maximum value of measurement of all pile driving operation events.
8.6
The
copies of calibration certificate of the monitoring equipment employed by the
Contractor for the construction vibration monitoring are attached in Appendix C.
8.7
In
the reporting month, construction vibration monitoring was carried out by the
Contractor for the built heritage feature at FL36 on a daily basis when pile
driving operation was conducted within 50m of construction work. No Limit Level
exceedance for construction vibration monitoring was recorded in the reporting
month. The monitoring results are provided in Appendix H.
8.8
Table 8.3 summarises
the vibration limit for construction vibration monitoring for surveyed cultural
heritage.
Table 8.3 Vibration Limit for
Construction Vibration Monitoring
|
Type of Building |
Guide Values of Maximum ppv*
(mm/Sec) |
|
|
Transient Vibration |
Continuous Vibration |
|
|
Vibration-sensitive
/ dilapidated buildings# |
7.5 |
3.0 |
|
Declared monuments/ Historical structures |
3.0 |
|
Remarks:
* peak
particle velocity
# as cultural heritages are
sensitive receivers, vibration monitoring should be classified as
vibration-sensitive.
8.9
If
any exceedance of limit have been found or damage to either structural or
non-structural elements of the historic buildings have been identified, the
construction works should stop immediately and seek structural engineer’s
advices for any remedial work.