● Residential Development at Lot. No. 70 Tsing Lung Tau, Tsuen Wan, N.T.: Natural Terrain Mitigation Measure

W T Chan & Associates Limited has been commissioned by Hanki Contractors (HK) & Associates Ltd. to undertake the site formation work - slope remedial works for 4 nos. of slope feature for Residential Development at Lot. No. 70 Tsing Lung Tau, Tsuen Wan, N.T.

The site formation work - slope remedial works consisted of soil nail & rock dowels installation, mass concrete retaining wall, buttress wall and drainage works. The works was approved by the “Buildings Department”.

Soil nails were installed to upgrade the slope feature and 9m height mass concrete wall was constructed for the potential failure of the out-site boundary feature. Also, rock dowels and pattern rock dowel with shotcrete cover were installed to remediate the locations of potential planar failure, wedge failure and overhang rock on the rock slope. Three buttress walls were constructed to protect the area of weak rock and support the overhang with potential toppling. For the remaining areas within the site formation works, soil nails were installed to upgrade the slope stability. Buttress wall was constructed to stable the boulder on the soil slope. Strengthening works including a concrete wall with tie backs were carried out for the existing buttress.

The maintenance staircase and the drainage system including stepped channel, downpipe, surface U channel, catchpits were constructed for the site formation–slope remedial works. All soil surfaces were installed erosion control mat and steel wire mesh with hydroseeding. All rock surface was installed a galvanized and PVC coated double twisted wire mesh.

Maintenance manual and updating the slope feature record were also prepared and submitted after the completion of works. The construction works were commenced in June 2017 and completed in July 2019.