Mission: Keep man-made slopes & retaining walls safe (I)

Keeping man-made slopes and retaining walls in good condition is essential. Even if they are designed and constructed to acceptable standards, without routine maintenance, their condition will deteriorate over time.  Introduction of proper “treatment” can prevent them from deterioration and collapse which may cause injury to persons or damage to your property, thus saving you a big fortune to make the slope safe, to repair your property and to compensate those injured.

How can we tell if the slopes and retaining walls have received proper “treatment”, i.e. routine maintenance? Below are some examples:

Vegetated Surface                    Shotcreted Surface

Chunam Surface                        Stone-pitched Surface vs Masonry Facing

Surface Drainage Measures

There are so many slopes and retaining walls in Hong Kong, how can we collaborate to ensure their safety? Government departments are responsible for maintaining government slopes. For example, road-side slopes are maintained by the Highways Department, while those in public housing estates, etc., are maintained by the Housing Department. The responsibility of private owners is as conferred by the lease documents issued by the Lands Department. If in doubt, you may wish to seek advice from lawyers or estate surveyors. If an owners’ corporation has been set up for your building, maintenance of the slopes should be coordinated by the corporation.

Basing maintenance work on inspection results

Is it necessary to repair the slopes/retaining walls? How should we repair them? It all depends on the results of Routine Maintenance Inspections. The main points of Routine Maintenance Inspections for slopes and retaining walls are as follows:

Routine Maintenance Inspections
                                                         
1.    Frequency: at least once a year
2.    Time-frame: inspections preferably to be conducted between October and February, and any required maintenance works to be completed before the onset of the wet season in April
3.    Inspection personnel: as professional geotechnical knowledge is not a must, inspections can be carried out by any responsible person, including property management staff or maintenance staff
4.    Inspection areas: man-made items on slopes or retaining walls + buried water-carrying services (e.g. water supply mains, sewers, stormwater drains, etc.) on or adjacent to soil slopes or retaining walls → “11+1 Actions”

“11+1 Actions”

Abnormal features

During Routine Maintenance Inspections, if anything considered to be unusual or abnormal, such as those shown below, is found, you should report promptly to the owner or the party responsible for maintaining the land, so that a professionally-qualified geotechnical engineer can be appointed without delay to undertake necessary actions.

Completing routine maintenance inspections is only half the work done! What’s next? Please read “Mission: Keep man-made slopes and retaining walls safe (II)”

For more details: Hong Kong Slope Safety website