Report No. : GEO Report No. 238

Report Title : Review of the 9 June 2006 and 16 July 2006 Washouts on Slope No. 11NW-B/FR60 behind Phoenix House, Lung Cheung Road (2008), 49 p.

Author : Maunsell Geotechnical Services Limited

Abstract

This report presents the findings of a review of two washouts (Incidents Nos. ArchSD/PM2/2006/06/0001 and ArchSD/PM2/2006/07/0001) that occurred in June and July 2006 on slope No. 11NW-B/FR60 behind Phoenix House, Lung Cheung Road. No casualties were reported as a result of either incident.

The first incident, which involved the washout of a fill slope above a mass concrete wall, occurred on 9 June 2006 when a Black Rainstorm Warning was in effect. The landslide debris, which had a volume of about 4 m³, was deposited on a shotcreted slope below the mass concrete wall.

The second incident occurred on 16 July 2006 when a Black Rainstorm Warning was in effect. This involved the washout of the recompacted backfill which was placed in early July 2006 as remedial works to the June 2006 washout, together with erosion at the slope toe. The landslide debris, which had a volume of about 8 m³, was deposited on the shotcreted slope below the mass concrete wall and partly washed down onto a garden to the east of slope No. 11NW-B/FR60.

The key objectives of the review were to document the facts about the washouts, present relevant background information and pertinent site observations made under this review. The scope of the review does not include any ground investigation or detailed diagnosis of the causes of the incidents. Recommendations for follow-up actions are reported separately.

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