Table 4 Problems that exist with the ten small, high hazard dams surveyed in Tan Moc commune
| Dam No. |
Height (m) |
Storage capacity (ML) |
Main problems associated with dam safety |
Acceptable or Unacceptable* |
| 1 |
4 |
600 |
Excessive vegetation on the upstream face, downstream face and crest of the dam; The crest is uneven; Upstream and downstream faces are substantially eroded; Spillway is concrete and in good condition. |
Unacceptable |
| 2 |
6 |
800 |
The top crest is damaged by traffic: dip on the crest; Slide on the upstream face; Excessive vegetation on the downstream face; Traffic damage and slide on the downstream; Spillway is in good condition. |
Unacceptable |
| 3 |
4 |
500 |
The top crest is damaged by traffic: dip on the crest; Slide on both the upstream and downstream faces of the dam; Spillway is in good condition; Excessive vegetation and trees. |
Unacceptable |
| 4 |
5 |
500 |
The top crest is damaged by traffic; Traffic damage on the downstream face; Slide on both the downstream and upstream faces; The crest is uneven; Two large holes on the top (serious); A lot of cracking on the top; Low area on the top; Spillway is appropriate. |
Unacceptable |
| 5 |
6 |
2500 |
Failed in 2008, about 20 houses flooded away; Cracking on the crest; Slide on both the upstream and downstream faces of the dam; Animal burrows; Spillway is in good condition. |
Unacceptable |
| 6 |
5 |
2000 |
Dams No. 5 and 6 caused a cumulative failure in 2008; Cracking; Excessive vegetation and trees on both downstream and upstream faces; Spillway is built of concrete and appropriate. |
Unacceptable |
| 7 |
5 |
600 |
Slide and cut on the top; Small and very old outlet; Cracking; Crest is uneven; There are a number of large trees; There is no spillway. |
Unacceptable |
| 8 |
2.5 |
350 |
The top is damaged by traffic; The crest is uneven, low areas on the top; Large hole on the crest; Slide; Small outlet and very small spillway (under-standard); Spillway is blocked by large trees. |
Unacceptable |
| 9 |
2 |
300 |
Failed in 2008 and repaired in 2009; Rice fields were damaged because of the failure in 2008; Slide; Cracking; The top is damaged by traffic. |
Unacceptable |
| 10 |
3 |
1000 |
The top is damaged by the traffic; Uneven crest and low areas on the top; Slide on the downstream; Excessive vegetation on both the downstream and upstream; Outlet is broken. Too old and cracking outlet; Spillway is too small; Spillway is blocked. |
Unacceptable |
Note: * Based on a dam inspection checklist developed from Ministry of Environment, Lands and Parks – Water Management Branch, British Columbia (1998) “Inspection & maintenance of dams – dam safety guidelines” and Department of Sustainability and Environment, the Victoria Government (2007) “Your dam – your responsibility: a guide to managing the safety of farm dams”.
