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”.
Sign up for our weekly news round-up!
Give your business an edge with our leading industry insights.