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 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, a vibration
monitoring plan was proposed for the surveyed cultural heritage based on the
Buildings Department’s Practice Note (PNAP) APP-137. For Castle Peak
Road Diversion under EP-466/2013/A, Kwu Tung North New Development Area Road
D1 to D5 under EP-468/2013/A, a vibration monitoring plan was proposed for the
surveyed cultural heritage, the Alert/Alarm/Action (3As) levels was adopted as recommended by the Antiquities and Monuments
Office (AMO). 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, no construction
vibration monitoring was conducted
for built heritage when no pile driving operation was conducted within assessment area of the construction
works. The location of the construction vibration monitoring stations was summarised in Table
8.1 and shown in Appendix K.
Table 8.1 Location
of Construction Vibration Monitoring
|
EP. No |
Contract No. |
Monitoring
Station (s) |
Nature
of Cultural Heritage |
Location
(s) |
|
NIL |
NIL |
NIL |
NIL |
NIL |
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 was conducted within the assessment area of construction works.
Table
8.2 Vibration Monitoring Plan
|
EP. No |
Contract No. |
Monitoring
Stations |
Distance
with Construction Works |
Monitoring
Plan |
|
NIL |
NIL |
NIL |
Within 50m |
Daily assessment is required |
|
Within 75m |
Bi-daily assessment is required |
|||
|
Within 100m |
Weekly assessment is required |
Remark:
[1] Baseline condition survey was conducted for
built heritage features at G202, G203, G303, G308, HKT03 and KT57 under
EP-468/2013/A, also HFL08, FL05, FL07, FL08, FL10, FL11, FL17, FL19, FL31 and
FL33 under ND/2019/04, and HFL05, FL02, FL04, FL24, FL27 and FL36 under
ND/2019/05 for EP-473/2013/A. As G202, G203, G303, G308, HKT03, KT57, HFL05, HFL08, FL02, FL04, FL05, FL07,
FL08, FL10, FL11, FL17, FL19, FL24, FL27, FL31, FL33 and FL36 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 is planned to be conducted throughout each event of the pile driving operation on daily /
bi-daily / weekly 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
No copies of calibration certificates of the
monitoring equipment employed by the Contractor of the
construction vibration monitoring are attached in Appendix C since no
vibration monitoring was conducted in the reporting period.
8.7
In the reporting month, no construction
vibration monitoring was carried out by the Contractor for the built heritage
features when no pile driving operation was conducted within 50m / 75m / 100m
respectively. No Limit Level exceedance for construction vibration monitoring
was recorded in the reporting month. The monitoring results, if any, are
provided in Appendix K.
8.8
Table 8.3 summarises the vibration
limits for construction vibration monitoring for surveyed cultural heritage under ND/2019/04 and ND/2019/05,
based on the Building Department’s Practice Note (PNAP APP-137).
Table 8.3 Vibration
Limits for Construction Vibration Monitoring (PNAP
APP-137)
|
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
Table 8.4 summarises
the vibration limits for construction vibration monitoring for surveyed
cultural heritage under ND/2019/02,
based on the Alert/Alarm/Action (3As) levels as recommended by the Antiquities
and Monuments Office (AMO).
Table
8.4 Vibration Limits for
Construction Vibration Monitoring (3As)
|
Buildings to be monitored |
Guide
Values (mm/Sec) |
||
|
Alert |
Alarm |
Action |
|
|
Vibration
(ppv*) |
5 |
6 |
7.5 |
Remarks:
* peak particle
velocity
8.10
If any exceedance of limits is found or
damage to either structural or non-structural elements of the historic
buildings is identified, the construction works should be stopped
immediately and structural engineer’s advices should be sought for any remedial work.