1. WORKSHOP ON DAM OPERATION By IR Chan Chiang Heng On 10th September 2014 At The Malaysian Water Association (Ground Floor)

2. Table of contents SECTION DESCRIPTION 1 Raw Water Sources 2
Operation of Regulating Dam 3
Critical Volume Assessment 4
Formulation of Contingency Plan 5
Effect of Reservoir Storage on Water Quality 6
Limnological Survey of Impounded Water 7
Treatment Problems and Solutions

3. SECTION 1
RAW WATER SOURCES

4. Raw water sources a) Surface Source River
River with augmentation from dam release
Irrigation Canal
Off River storage
River Bank Filtration System

5. Sg. Selangor Phase 1 (SSP1)- Intake

6. Sg. Sireh Intake

7. c) Impounded Source (Dam) Classification by Function
b) Underground Source
Well
c) Impounded Source (Dam)
Classification by Function
Classification
Example
Dam Owner
Water Supply
Direct Abstraction
Dam Release (Regulating Dam)
Klang Gates Dam
Sungai Tinggi Dam WA
b) Irrigation
Pedu Dam
MADA
c) Flood Mitigation
Sungai Batu Dam
JPS d)
Flood Mitigation and Water Supply
Water Supply and Flood Mitigation
e) Hydro Electric
Temenggong Dam
TNB

8. NOTES:
1) The Dam owner has control over:-
Dam level (Volume)
Point of Dam release (Water Quality)
Quantity of Dam Release

11. 2) All raw water sources do present some form of treatment problem
2) All raw water sources do present some form of treatment problem. The extent of treatment problem or pollution varies from source to source.
3) Most water supply dam function as regulating dam i.e. Releases are made during draught to augment flow in river.

12. OPERATION OF REGULATING DAM
SECTION 2
OPERATION OF REGULATING DAM

13. Operation of regulating dam
OPERATION PROTOCOL
DEFINITION – Regulating dam: constructed to store water during wet spell and dam release during drought to augment low river flow.
Flow to river at periodicals
low river flow
Controlled release
(from impounded reservoir)
Ensure adequate river level
Augment flow in the river at Intake

14. Overflow
Dam Release
Sg. Selangor Dam

15. B)ACQUISITION OF DATA & THEIR APPLICATION
I) At Dam
a) Catchment Area
Upstream of dam
For impounded reservoir volume estimation.
b) Rainfall
- In catchment of dam (daily).
For estimation of possible increase in volume of impounded water.
c) Characteristic of Impounded water
- Frequent initially.
- Thereafter bimonthly or monthly.
For planning the treatment of water released at different levels of the impounded reservoir. Monitoring the water quality by conducting limnological survey.
d) Dam Level (daily)
For trending the decrease or increase in dam level and volume. Documenting the acquired data will indicate a cut back or increase in production.
e) Record of quantity of release at varying times (when required).
This information coupled with base flow in river will enable the likely water quantity at the abstraction point to be predicted.

16. II) At Intake (a) Water level in river (i) Under normal flow condition
(recording at 12 or 24 hourly
will suffice).
ii) During drought recording of
level at close interval is
necessary. 6 to 8 hours is likely
the frequency.
For base flow volume and recession
constant estimation.
For river level monitoring, the installation of an automatic level recorder is ideal.
(b) Rainfall
In catchment of tributaries.
For estimation of flow volume from tributaries into main river
In relation to forecast of dam releases
(c) Other users likely are the following:-
- Compensation water.
- Irrigation.
- Water treatment plant upstream.
To note water quantity requirement for estimation of required volume at intake in relation to available volume.

17. c) APPLICATION OF RELEVANT DOCUMENTS FOR RESERVOIR OPERATION
Rules for
Reservoir Operation
Elevation-Storage-Area Curve
Reservoir Control Curve
Estimation of Time of Travel
Recession Constant
Regulation of Discharge

18. SG. TINGGI RESERVOIR Elevation-Storage-Area Curve 70 60 50 40 30 20 10
Availability of surface area at different elevation.
Storage / Elevation
Area / Elevation
Elevation - metre
Storage – cubic metre 1 x 106

19. Reservoir Control Curves
2020 MLD MLD MLD MLD
110
100 90 80 70 60 50 40 30 20 10
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
NOV
DEC
Abstraction rates of 2020, 1900, 1700 and 1300 MLD were selected at intake for Sg Tinggi Dam
Total Reservoir Storage (MCM)

20. Estimation Time of Travel
Based on the observation of the travel time of the wave generated when water was released from the dam to the intake
Time observed : hours
Factors to be considered:
Ground Condition along the flow path
Ground terrain along the flow path related to the rate of dam release
Possible abstraction of water by others
Weather at time of study of time travel

21. Recession constant applicable to any river reach
Value obtained from the equation
Reliable values of k can be derived when it is consistently dry across a river basin for many days
Total River flow= Spill Over Weir + Abstraction + Dam release
Base River Flow = Total River Flow – Dam Release
Min. Base Flow = Compensation Flow + Abstraction
q=qo x kt
Flow at any time
Recession constant applicable to any river reach
Flow t days later
Kt = of base flow

22. Regulation of Discharge Reservoir (dam) release
Factors to consider:
- River level.
- Base River Flow.
- Impending Weather Condition.
- Available Volume in Dam.
- Affordable Quantity of release

23. CRITICAL VOLUME ASSESSMENT
SECTION 3
CRITICAL VOLUME ASSESSMENT

24. CRITICAL VOLUME
Active volume available in dam when the volume of dam release has to be regulated or controlled (restricted) to tie over an impending dry period.
Water rationing may have to be implemented during controlled dam release period.

25. Active volume Total Volume = Active Volume + Dead Volume
Active volume = Total Volume – Dead Volume
Dead volume is defined as the volume of water below the lowest outlet or drawoff level.

26. EMPANGAN SG. TERIP DAM DRAWOFF TOWER Syphon No. 1
TWL M
Syphon No. 1
Crown Level = M
Spill Level = M
Inlet Soffit Level = M
Inlet Cill Level = M
100.75M
99.65M
95.70M
94.60M
Syphon No. 2
Crown Level = M
Spill Level = M
Inlet Soffit Level = M
Inlet Cill Level = M
92.50M
91.50M
87.70M
86.60M
84.60M
Syphon No. 3
83.50M
Crown Level = M
Spill Level = M
Inlet Soffit Level = M
Inlet Cill Level = M
79.70M
78.60M

27. LOWEST

28. SG. TINGGI DAM DRAWOFF TOWER – VALVE ARRANGEMENT
Parallel Face Sluice Valve
Regulating Valve
Guard Valve
Air Valve

29. Advanced assessment of critical volume
Every dam has its critical volume
The specific critical volume of any specific dam varies with the weather condition in respect of time and quantity.
To determine the relevant volume to choose from tabulate available active volume in advance based on the following percentages:
75%
60%
50%
40%

30. AVAILABLE VOLUME BETWEEN DEPTHS Tabulations for Sungai Tinggi Dam
Tabulation Of Data of Active Volume
Available volume between depths from top water level to first drawoff outlet and between subsequent drawoff outlet
AVAILABLE VOLUME BETWEEN DEPTHS Tabulations for Sungai Tinggi Dam
Dam Level (M) Interval Volume Comments
57.00 to M MG TWL is at 57.00M
(70.01ML)
 53.00 to M MG M is the 1st
(57.51ML) Drawoff Level
 49.00 to M MG
(43.73ML)
 45.00 to M 7.70MG M is the 2nd
(35.00ML) Drawoff Level
 41.00 to M 9.24MG
(42.01ML)
 36.00 to M 7.56MG M is the 3rd
(34.37ML) Drawoff Level

31. DAM VOLUME AT 0.01M INTERVAL (Sungai Tinggi Dam-Tabulation)
Level M to 53.00M
Depth Interval M
Total Depth Difference M
Vol. at this Depth Interval MG
Tot. Volume Difference MG
56.81
56.80
56.79
56.78
56.77
56.76
56.75
56.74
56.73
56.72
56.71
56.70
56.69
56.68
56.67
56.66
56.65
56.64
56.63
56.62
56.61
56.60
Level (M)
Volume (MG)
56.99
56.98
56.97
56.96
56.95
56.94
56.93
56.92
56.91
56.90
56.89
56.88
56.87
56.86
56.85
56.84
56.83
56.82

32. Between Critical Depth
Definition: Elevation or level of water in reservoir coinciding with the selected critical volume.

33. FORMULATION OF CONTIGENCY PLAN
SECTION 4
FORMULATION OF CONTIGENCY PLAN

34. FORMULATION OF CONTIGENCY PLAN
Contingency plan can be formulated in advance for any active volume in dam and dam level.
Criteria involved in a plan formulation are as follows:
Volume of dam release
A range of volume – Values based on past record related to river flow quantity and current based condition.
Sustaining period selected– related to weather condition and active volume available.
In contingency plan formulation rainfall is not taken into consideration. Any rainfall occurs during the planned period is considered a bonus.

35. Example of Formation of Contingency Plan
a) Status of available vol. in dam as on 5/7/2002:-
Dam level = 53.32M
Tot. Active Vol. = 74,140 ML or 75.26% of Tot. active vol of
98,503ML
Planning Strategy:-
Consider – Critical level, Critical volume & sustaining period
Critical Volume
Dam
Level
(m)
Active Volume
At Specific
Level (ML)
Volume
Between
Specific (ML)
Percentage
To Total
53.32
74,140
75.26
26.640
49.00
47,500
48.22
8,750
47.00
38,750
39.34
Critical level
1st critical level of 49.00M
2nd critical level of 47.00M

36. b) Sustaining period Available Volume (ML) Rate of Dam Release (MLD)
800
700
600
500
400
300
Sustaining Period In Days
1st Critical Level
(53.32M to 49.00M)
26,640
2nd Critical Level
(49.00M to 47.00M)
8,750 33 11 38 13 47 15 53 18 67 22 89 29
Total 44 51 59 71
118

37. Effect of reservoir storage on water quality
SECTION 5
Effect of reservoir storage on water quality

38. WATER QUALITY IN DEEP RESERVOIRS
Introduction
Seasonal density or thermal stratification varies for shallow (less than 6M) and deep (greater than 6M) lakes and reservoirs.
In shallow reservoirs, water temperatures and oxygen concentrations will depend on the amount of wind induced mixing.
At surface, water temperatures rise in relation to bottom waters, stratified density layers will form in the water column.
An oxygen defiency will result at the sediment – water interface, creating anaerobic conditions that will solubilize nutrients and metals from bottom sediments.
Deep water bodies experience thermal stratification and form three distinct layers of water below the surface.
Top layer is called epilimnion.
Bottom layer is called hypolimnion.
The layer between is called metalimnion (thermocline).

39. WATER QUALITY IN DEEP RESERVOIRS
Thermocline:Intermediate/boundary layer that has sharp change in both temperature and density
Epilimnion: Upper layer of well-mixed warm water
Epliminion (warm, aerobic, well-mixed)
30oC
28.5oC
Thermal Stratification
Thermocline (sharp change in both temperature & water density)
Hypolimnion (cool, anaerobic, poorly mixed)
Lake
Hypolimnion: Lower layer, poorly mixed cool water. Low DO and anaerobic.

40. CASE STUDIES 1)Demonstration by color intensity-Malut Dam
Raw Water at Varying Depth

41. Treated Water at Varying Depth

42. LIMNOLOGICAL SURVEY OF IMPOUNDED WATER
SECTION 6
LIMNOLOGICAL SURVEY OF IMPOUNDED WATER

43. OBJECTIVE
To determine the raw water quality at varying depth in the impoundment or dam
For a dam, the survey is conducted at varying depth in the Epilimnion, the Thermocline at the Hypolimnion.
Knowing the water quality will facilitate treatment of the impounded water.

44. PARAMETERS TO RECORD SAMPLING POINT
At surface and at each drawoff point for a dam provided with a variable drawoff tower.
PARAMETERS TO RECORD pH
Colour
Turbidity
Iron (Soluble and Insoluble Form)
Manganese (Soluble and Insoluble Form)
Dissolved oxygen
Alkalinity
Hydrogen Sulphide

45. SAMPLING FREQUENCY Weekly initially, thereafter bimonthly and monthly.
The frequency is dictated by water level or volume of water in the impoundment.

46. TREATMENT PROBLEM
Soluble manganese and iron are the common treatment problem encounters.
Aeration of the dam normally overcames this problem.

47. quality OF IMPOUNDED WATER
Influent Quality
Siting of the reservoir
Depth of reservoir
- depth of reservoir< 6.0M  shallow
- depth of reservoir> 6.0M  deep
 stratify thermally
INFLUENTIAL
FACTORS
Detrimental effects:-
a) Thermal and chemical stratification
b) Algae problems
c) Insufficient or minimal mixing of
inflowing raw water with stored
water

48. WATER QUALITY - Sungai Tinggi Dam
Parameter 
Epilimnion
Hypolimnion
1.0 Physical Changes
a) pH
b) Colour (HU)   
c) Turbidity (NTU) 
6.5 to 7.2
Higher value due to algae action (photosynthesis)
35 to 150
3 to 28
Sedimentation
6.0 to 6.5
Lower value due to Stratification.
375 to 625
Decay of vegetation and leaching of organic matter from the soil.
6 to 66
Result of suspended matter.
d) Temperature C
30 to 32
Subject to sunlight and
wind action.
28 to 29
Shielded by the thermocline.

49. Parameter Epilimnion Hypolimnion
2.0 Chemical Changes
a) Dissolved Oxygen
mg/l
b) Iron mg/l
c) Manganese (mg/l)
d) Ammonia as N
(mg/l)
e) Alkalinity as CaCO3
5 to 7
Exposed to atmosphere and wind action.
0.40 to 1.50
High dissolved oxygen content (aerobic condition resulting in precipitation).
0.03 to 0.07
High dissolved Oxygen content.
0.10 to 0.13
Nitrification can bring about a reduction in
ammonical Nitrogen in the aerated surface waters.
4.4 to 6.9
Algae remove calcium carbonate and CO2 by photosynthesis. The result is an increase in pH and decrease in calcium carbonate.
2 to 5
Shielded from atmosphere and wind action.
7 to 20
Low dissolved oxygen Content (anaerobic condition, Metal remain in soluble state).
0.07 to 0.30
Low dissolved oxygen content.
0.54 to 1.73
Increase in the cold anaerobic stagnant
zone.
 8.9 to 17.2

50. Treatment problems and solutions
SECTION 7
Treatment problems and solutions

51. TREATMENT CHANGING FORM OF METAL Aeration Use of Chemicals
Source – Dam (Jetting, Mechanical pumping, Injection)
Treatment Plant – Aerator (Cascading/Trickling Aerator)
Oxidants: Potassium permanganate, chlorine, ozone, chlorine dioxide.
Most favored!

52. THEORY Metals (general)
Source
Natural (a)
Found in most natural waters
- dissolution of rocks and minerals.
(b)
The hypolimnion of dam
- the dark, cold and anaerobic.
Man-made
Industrial discharge.
Type
Iron (Fe), Manganese (Mn).
Form
Soluble and insoluble (particulate)
Total (Fe) or (Mn) = Soluble + Insoluble Form
Analytical
Analysis
Total Metal (Fe or Mn) Acidify Sample and Boil
Soluble Metal (Fe or Mn) - Filter sample through a 0.45 Ωm filter
paper.

53. THEORY Metals (general)
Removal
Insoluble Form
by coagulation and flocculation and filtration
Soluble Form
By first converting from soluble to insoluble followed by coagulation and flocculation and filtration
Thus, it is easier to remove in the insoluble form than in the soluble form.
In general, both iron and manganese invariably occur in both the insoluble and soluble form.

54. TREATMENT Conversion of Form Oxidation Process (1) Aeration
(Physical Means)
(2) Use of Chemical
(Chemical Means)

55. TREATMENT (1) Aeration (Physical Means) The function of aeration
To introduce oxygen to the water.
To remove carbon dioxide (resulting in increase of
pH).
Removal of iron and manganese is pH dependent,
more so with manganese.
Nature’s Way

56. Oxidation Of Fe & Mn – Sg. Terip Dam

57. Oxidation Of Fe & Mn – Sg. Terip Dam

58. Oxidation Of Fe & Mn At Pedas Lama WTP from Beringin DAM, Negeri Sembilan

59. Oxidation Of Fe & Mn At Scour - Malut Dam

60. Oxidation Of Fe & Mn At Scour - Sg. Semenyih Dam

61. Quality Surveillance of
Treatment of Impounded Water
Contaminants, Iron and Manganese
Weir Downstream of The Dam Intake
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
Quality Surveillance of
Sg. Semenyih Dam to
Intake (Year 1994)
06 Jan
20 Jan
03 Feb
17 Feb
03 Mac
24 Mac
14 Apr
28 Apr
12 May
26 May
16 Jun
30 Jun
11 Aug
25 Aug
14 Jul
28 Jul
08 Sep
22 Sep
06 Oct
27 Oct
10 Nov
24 Nov
15 Dec
29 Dec \
IRON (ppm)
Dates of Sampling

62. TREATMENT
Man-Made
Aeration at Source
(a) Dam

63. View Of Air Diffuser – Sg. Terip Dam

64. Stainless Steel pipe (grade 304)
SIDE VIEW OF DIFFUSER
DETAILED C1
20mm
Stopper Cap
20MM X 5 MM
Reinforced rubber nose
Perforated stainless
Steel pipe
Stainless Steel pipe
(grade 304)
Cross Connector
0.75M C1
Concrete Sinker
0.5M
0.5M
Concrete Sinker
PLAN VIEW OF DIFFUSER 6M
Renforced Rubber Hose
Threaded Ends
Perforated stainless
Steel pipe
Concrete Sinker 6M
Cross Connector
Cross Connector
Stainless Steel pipe C2
Cross Connector
Stainless Steel pipe (grade 304)
Source from UTM
DETAILED C2

65. Variation of DO vs Depth After Aeration at Location 2
Aeration Hrs: 0.00
Aeration Hrs:
Aeration Hrs:
6.00
5.50
5.00
4.50
4.00
3.50
3.00
2.50
2.00
1.50
1.00
0.50
0.00
Dissolved Oxygen (mg/L) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
4.7
4.6
4.5
4.4
4.3
4.2
4.0
3.9
0.4
0.3
0.2
0.0
3.0
2.7
2.5
2.4
2.2
1.9
1.5
0.1
5.9
5.8
5.2
5.0
4.9
4.1
3.8
3.7
3.6
3.3
2.3
1.2
1.1
1/9/02
15/9/02
29/9/02

66. Variation of DO at Different Drawoff Level
DO ( ) DO ( ) DO ( )
6.50
6.00
5.50
5.00
4.50
4.00
3.50
3.00
2.50
2.00
1.50
1.00
0.50
0.00
Dissolved Oxygen (mg/L)
1st Drawoff
Level = 73.00m
2nd Drawoff
Level = 66.60m
3rd Drawoff
Level = 60.20m
4th Drawoff
Level = 53.80m
Drawoff Level

67. TREATMENT (2) Use of Chemicals (Chemical Means) Chlorine
Chlorine Dioxide
Ozone
Potassium Permanganate (KMnO4)

68. USE OF CHEMICALS (CHEMICAL MEANS)
(a) Use of Potassium Permanganate
Advantage
Besides effective in removal of iron and manganese, it also helps in the reduction of TOC (Total Organic Carbon).
Analytical Analysis
The optimum dosage and time of reaction has first to be determined.
Adverse Effect of Over Dosage
Colour, add manganese to water.

69. (a) Use of Potassium Permanganate
JAR TEST ON USE OF POTASSIUM PERMANGANATE (KMn04)
To determine KMnO4 Dosage and Reaction Time
Table 1 : Raw Water Quality
Date
06/10/03 pH
6.21
Turbidity (NTU)
97.1
Apparent Colour (Pt.Co)
521
Manganese total (mg/L)
0.224
Manganese soluble (mg/L)
0.128
Iron (mg/L)
0.132
Aluminium (mg/L)
0.038
TOC
3.90

70. Table 2 : Jar Test Data
Date of Test
24/09/03
Beaker No 1 2 3 4 5 6
Pre-lime (mg/L)
Potassium Permanganate (mg/L)
0.00
0.10
0.20
0.30
0.40
0.50
Liquid Alum Dosage (as mg/L product) 24
Flocculant AN910 (mg/L)
Floc Size d3
Settled water quality
SW pH
6.13
6.12
6.15
6.10
6.08
6.11
SW Turbidity (NTU)
3.76
3.82
3.58
3.55
3.68
3.65
SW Colour (Pt-Co) 24 21 22
SW Fe (mg/L)
0.12 -
0.11
0.13
SW Al (mg/L)
0.098
0.073
0.061
0.054
SW Mn (mg/L)
0.096
0.091
0.082
0.066
0.078
0.085
SW TOC (mg/L)
2.7
2.1
1.8

71. Table 3 : Jar Test Data
Date of Test
24/09/03
Beaker No 1 2 3 4 5 6
Pre-lime (mg/L)
Potassium Permanganate (mg/L)
0.30
Retention time for KMnO4 Dosing (mm) 11 9 7
Liquid Alum Dosage (as mg/L product) 24
Flocculant AN910 (mg/L)
0.10
Floc Size d3

72. Table 4 : Jar Test Data
Settled water quality
Beaker No. 1 2 3 4 5 6
SW pH
6.10
6.09
6.11
6.08
6.05
6.07
SW Turbidity (NTU)
3.08
2.85
2.72
2.75
2.73
2.71
SW Colour (Pt-Co) 20 19 18
SW Fe (mg/L) -
0.11
0.12
SW Al (mg/L)
0.056
0.055
0.057
SW Mn (mg/L)
0.016
0.017
0.020
0.032
0.046
SW TOC (mg/L)
1.9
2.0
2.1
Filtered water quality
FW Turbidity (NTU)
0.341
0.348
0.335
0.329
0.389
0.350
FW Colour (Pt-Co) 6 5
FW Fe (mg/L) -
0.01
FW Al (mg/L)
0.08
0.07
FW Mn (mg/L)
0.009
0.010
0.012
0.014
0.023
0.028
FW TOC (mg/L)
1.7
1.8
2.0

73. Use of Potassium Permanganate - SSP 1

74. b) Use of chemicals (Coagulant)
Appropriate Choice of Coagulant

75. Coagulant PAC – Filter – SSP1

76. Coagulant Alum – Filter – SSP1

77. THANK YOU