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沙井測量
Manhole Survey
Manhole Survey was carried out prior to CCTV survey to measure the conditions of manholes and related pipe information.
Manhole Survey Measurement
Measurement of pipe depths must always be taken from the point on the cover frame above the‘X’pipe, this point should be marked with a spray painted ‘T’.
All pipe depths should be taken from this ‘T’ point vertically and not on an angle.
The way to do this is to measure the shaft depth D and then measure the depths from where the pipe enter the chamber to the underside of the slab and add the two together,
i.e. D + F, D + E or D + G.
Where the chambers have a
tapered slab the measurement of
depths is more difficult but is still
measurable as follows.
Standard sizes for drainage and sewerage pipes are as follow:
100 mm, 150 mm, 225 mm, 300 mm, 375 mm, 450 mm, 525 mm, 600 mm,
750 mm, 900 mm, 1050 mm, 1200 mm, 1350 mm, 1500 mm etc.
a.) When measured size is less than 10mm from the standard size, use standard size.
b.) When measured size is more than 10mm from the standard size use actual size.
Example:
Measured Sized Filled in Size
| 90 mm |
100 mm |
| 595 mm | 600 mm |
| 80 mm | 80 mm |
| 1000 mm | 1000 mm |
| 550 mm | 550 mm |
Method of Measuring of Standard Pipe Size:
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| 量度沙井尺寸 |
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沙井內部 |
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FORWIN Site Investigation Engineering Ltd.
