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WORKSHOP ON DAM OPERATION BY IR CHAN CHIANG HENG ON 10 TH SEPTEMBER 2014 AT THE MALAYSIAN WATER ASSOCIATION (GROUND FLOOR)

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Presentation on theme: "WORKSHOP ON DAM OPERATION BY IR CHAN CHIANG HENG ON 10 TH SEPTEMBER 2014 AT THE MALAYSIAN WATER ASSOCIATION (GROUND FLOOR)"— Presentation transcript:

1 WORKSHOP ON DAM OPERATION BY IR CHAN CHIANG HENG ON 10 TH SEPTEMBER 2014 AT THE MALAYSIAN WATER ASSOCIATION (GROUND FLOOR)

2 TABLE OF CONTENTS SECTIONDESCRIPTION 1Raw Water Sources 2Operation of Regulating Dam 3Critical Volume Assessment 4Formulation of Contingency Plan 5Effect of Reservoir Storage on Water Quality 6Limnological Survey of Impounded Water 7Treatment Problems and Solutions

3 SECTION 1 RAW WATER SOURCES

4 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 b) Underground Source Well c) Impounded Source (Dam) Classification by Function ClassificationExampleDam Owner a)Water Supply Direct Abstraction Dam Release (Regulating Dam) Klang Gates Dam Sungai Tinggi Dam WA b) IrrigationPedu DamMADA c) Flood MitigationSungai Batu DamJPS d) Flood Mitigation and Water Supply Water Supply and Flood Mitigation Sungai Batu Dam Klang Gates Dam JPS WA e) Hydro ElectricTemenggong DamTNB

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

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11 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 SECTION 2 OPERATION OF REGULATING DAM

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

14 Sg. Selangor Dam Dam Release Overflow

15 B)ACQUISITION OF DATA & THEIR APPLICATION 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. I) At Dam

16 (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 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. II) At Intake

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 Elevation - metre Storage – cubic metre 1 x Storage / Elevation Area / Elevation Availability of surface area at different elevation.

19 JANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDEC MLD 1900MLD 1700MLD 1300MLD Total Reservoir Storage (MCM) Reservoir Control Curves Abstraction rates of 2020, 1900, 1700 and 1300 MLD were selected at intake for Sg Tinggi Dam

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 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=q o x k t Flow at any time Flow t days later Recession constant applicable to any river reach K t = 0.95 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 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 M TWL M M 99.65M 95.70M 94.60M 92.50M 91.50M 87.70M 86.60M 84.60M 83.50M 79.70M 78.60M Syphon No. 2 Syphon No. 3 Crown Level = M Spill Level = 99.65M Inlet Soffit Level = 95.70M Inlet Cill Level = 94.60M Crown Level = 92.50M Spill Level = 91.50M Inlet Soffit Level = 87.70M Inlet Cill Level = 86.60M Crown Level = 84.60M Spill Level = 83.50M Inlet Soffit Level = 79.70M Inlet Cill Level = 78.60M

27 LOWEST

28 SG. TINGGI DAM DRAWOFF TOWER – VALVE ARRANGEMENT Parallel Face Sluice Valve Air ValveGuard Valve Regulating 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 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)IntervalVolumeComments to M15.40MGTWL is at 57.00M (70.01ML) to M12.65MG 49.00M is the 1st (57.51ML) Drawoff Level to M9.62 MG (43.73ML) to M7.70MG 41.00M is the 2nd (35.00ML)Drawoff Level to M9.24MG (42.01ML) to M7.56MG 32.00M is the 3rd (34.37ML)Drawoff Level

31 DAM VOLUME AT 0.01M INTERVAL (Sungai Tinggi Dam-Tabulation) Level (M)Volume (MG) Level 57.00M to 53.00M Depth Interval 0.01M Total Depth Difference 4.00 M Vol. at this Depth Interval 15.40MG Tot. Volume Difference MG

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

33 SECTION 4 FORMULATION OF CONTIGENCY PLAN

34 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 i.A range of volume – Values based on past record related to river flow quantity and current based condition. ii.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 level 1 st critical level of 49.00M 2 nd critical level of 47.00M Dam Level (m) Active Volume At Specific Level (ML) Volume Between Specific (ML) Percentage To Total Active Volume , , , , Critical Volume

36 b) Sustaining period Available Volume (ML) Rate of Dam Release (MLD) Sustaining Period In Days 1 st Critical Level (53.32M to 49.00M) 26,640 2 nd Critical Level (49.00M to 47.00M) 8, Total

37 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 Epliminion (warm, aerobic, well-mixed) 30 oC 28.5 oC Thermal Stratification Thermocline (sharp change in both temperature & water density ) Hypolimnion (cool, anaerobic, poorly mixed) Lake Epilimnion: Upper layer of well-mixed warm water Thermocline:Intermediate/boundary layer that has sharp change in both temperature and density 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 SECTION 6 LIMNOLOGICAL SURVEY OF IMPOUNDED WATER

43 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. OBJECTIVE

44 At surface and at each drawoff point for a dam provided with a variable drawoff tower. SAMPLING POINT a) pH b) Colour c) Turbidity d) Iron (Soluble and Insoluble Form) e) Manganese (Soluble and Insoluble Form) f) Dissolved oxygen g) Alkalinity h) Hydrogen Sulphide

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

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

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

48 Parameter EpilimnionHypolimnion 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 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. WATER QUALITY - SUNGAI TINGGI DAM

49 Parameter EpilimnionHypolimnion 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 CaCO 3 (mg/l) 5 to 7 Exposed to atmosphere and wind action to 1.50 High dissolved oxygen content (aerobic condition resulting in precipitation) to 0.07 High dissolved Oxygen content 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 CO 2 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) to 0.30 Low dissolved oxygen content to 1.73 Increase in the cold anaerobic stagnant zone. 8.9 to 17.2

50 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 ) SourceNatural (a)Found in most natural waters - dissolution of rocks and minerals. (b)The hypolimnion of dam - the dark, cold and anaerobic. Man-madeIndustrial discharge. TypeIron (Fe), Manganese (Mn). FormSoluble 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 FormOxidation Process (1) Aeration(Physical Means) (2) Use of Chemical(Chemical Means)

55 (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 TREATMENT

56 Oxidation Of Fe & Mn – Sg. Terip Dam

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

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

63 View Of Air Diffuser – Sg. Terip Dam

64 Reinforced rubber nose Cross Connector Perforated stainless Steel pipe Concrete Sinker SIDE VIEW OF DIFFUSER C1C2 6M PLAN VIEW OF DIFFUSER Concrete Sinker Perforated stainless Steel pipe Cross Connector 6M 0.75M 0.5M Stopper Cap Stainless Steel pipe (grade 304) Concrete Sinker DETAILED C1 20MM X 5 MM 20mm Cross ConnectorStainless Steel pipe Threaded Ends DETAILED C2 Stainless Steel pipe (grade 304) Cross Connector Renforced Rubber Hose Source from UTM

65 Variation of DO vs Depth After Aeration at Location Aeration Hrs: Aeration Hrs: Aeration Hrs: /9/02 15/9/02 29/9/02 Dissolved Oxygen (mg/L)

66 Variation of DO at Different Drawoff Level Dissolved Oxygen (mg/L) 1 st Drawoff Level = 73.00m 2 nd Drawoff Level = 66.60m 3 rd Drawoff Level = 60.20m 4 th Drawoff Level = 53.80m Drawoff Level DO ( ) DO ( ) DO ( )

67 (2) Use of Chemicals (Chemical Means)  Chlorine  Chlorine Dioxide  Ozone  Potassium Permanganate (KMnO 4 ) TREATMENT

68 (a) Use of Potassium Permanganate USE OF CHEMICALS (CHEMICAL MEANS) AdvantageBesides 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 JAR TEST ON USE OF POTASSIUM PERMANGANATE (KMn0 4 ) To determine KMnO 4 Dosage and Reaction Time Table 1 : Raw Water Quality Date06/10/03 pH6.21 Turbidity (NTU)97.1 Apparent Colour (Pt.Co)521 Manganese total (mg/L)0.224 Manganese soluble (mg/L) Iron (mg/L)0.132 Aluminium (mg/L)0.038 TOC3.90 (a) Use of Potassium Permanganate

70 Date of Test24/09/03 Beaker No Pre-lime (mg/L) Potassium Permanganate (mg/L) Liquid Alum Dosage (as mg/L product)24 Flocculant AN910 (mg/L)0.10 Floc Sized3d3 d3d3 d3d3 d3d3 d3d3 d3d3 Table 2 : Jar Test Data Settled water quality SW pH SW Turbidity (NTU) SW Colour (Pt-Co) SW Fe (mg/L) SW Al (mg/L) SW Mn (mg/L) SW TOC (mg/L)

71 Date of Test24/09/03 Beaker No Pre-lime (mg/L) Potassium Permanganate (mg/L)0.30 Retention time for KMnO 4 Dosing (mm) Liquid Alum Dosage (as mg/L product)24 Flocculant AN910 (mg/L)0.10 Floc Sized3d3 d3d3 d3d3 d3d3 d3d3 d3d3 Table 3 : Jar Test Data

72 Table 4 : Jar Test Data Filtered water quality FW Turbidity (NTU) FW Colour (Pt-Co) FW Fe (mg/L) FW Al (mg/L) FW Mn (mg/L) FW TOC (mg/L) Settled water quality Beaker No SW pH SW Turbidity (NTU) SW Colour (Pt-Co) SW Fe (mg/L) SW Al (mg/L) SW Mn (mg/L) SW TOC (mg/L)

73 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


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