Behind the Mid-Levels disaster
To this engineer, the article headlined 'Fears grow over cracks near landslide site' (February 17), about Po Shan Road, reads so much like history repeating itself.
In 1972, Tony Vail and I were involved in inspecting the aftermath of the landslide that occurred in June during the excavation of the site at 51 C & D Conduit Road just below Po Shan Road.
Resulting from the government's Mid-Levels geotechnical studies in the early 1980s a considerable amount is now known about the geology, hydrogeology and geotechnical properties of the soils and rocks of the area, including 55 Conduit Road and 10-16 Po Shan Road, both mentioned in your article.
However, I think that it would be worth someone's time rereading the 'Final Report of the Commission of Inquiry into the Rainstorm Disasters 1972' published by the Hong Kong Government Printer (November 1972). This will allow the reader to appreciate the considerable time scale involved from when we first became aware that there was a possible problem to the actual occurrence of the catastrophic landslide that demolished Kotewell Court (38-40 Kotewall Road) during the rainstorm on the evening of June 18, 1972, with the loss of 67 lives.
Over a period of several months, cracks appeared in Po Shan Road above the excavation at 51 C & D Conduit Road. They were inspected and I believe that discussions were held on the likely effect of any slope failure. Nevertheless, at the time no one appreciated the scale of the disaster that was to overtake the area on that fateful evening. What had taken several months to develop was all over in seconds as the water table in the colluvial soil rose during the rainstorm.
For the peace of mind of everyone in the area, both the Government Civil Engineering Office and the developer of 55 Conduit Road need to be open about the causes of the problem and the action that is being taken to ensure that there can be no recurrence of a 1972-type disaster.
DAVID EASTAFF, Milton Keynes, United Kingdom