Drinking Water Operator Certification Review

Transcription

1 Drinking Water Operator Certification Review 1

2 Vocabulary Aerobic A condition in which atmospheric or dissolved molecular oxygen is present in the aquatic (water) environment Anaerobic A condition in which atmospheric or dissolved molecular oxygen is NOT present in water 2

3 Vocabulary Culinary Fit for human consumption Potable Water that does not contain objectionable pollution, contamination, minerals, or infective agents and satisfactory to drink Palatable Water that is pleasing to the senses (desirable temp., free from objectionable tastes, odors, colors, & turbidity) 3

4 Vocabulary Aesthetics Attractive or appealing Taste, odor, or color Things that affect the aesthetics of water: Extreme hardness High total dissolved solids 4

5 Terminology GPM Gallons per minute (gal/min) MGD Million gallons per day (M gal/day) TTHM Total trihoalomethne PSI Pounds per square inch (lbs/in 2 ) mg/l Milligrams per liter (ppm = parts per million) 5

6 Terminology MCL = NTU = Maximum Contaminate Level Nephelometric Turbidity Units The cloudy appearance of water caused by the presence of suspended and colloidal matter A turbidity measurement is used to indicate the clarity of water A nephelometer measures particle-reflected light at a 90 o angle 6

7 Terminology Electrolysis Decomposition of material by an outside electric current Current is created by the movement of water in a pipe Question: How do you protect your system from electrolysis? Answer: Install Cathodic Protection 7

8 Terminology Water Hardness A characteristic of water caused mainly by salts of calcium and magnesium, such as bicarbonate, carbonate, sulfate, chloride and nitrate Causes formation of soap curds Increases use of soap Deposits of scale in boilers and fixtures Damages some industrial processes Causes objectionable tastes in water 8

9 Terminology ph An expression of the intensity of the basic or acidic condition of a liquid ph scale 0 to 14 7 is neutral ph greater than 7 is considered basic ph less than 7 is considered acidic 9

10 Rules and Regs Review Name of Contaminant MCL Comments Fluoride 4 mg/l Field test = SPADNS TTHMs 80 ppb For SW systems serving a population of 10,000 or greater 10

11 Rules and Regs Review Name of Contaminant Copper Lead MCL Action Limit 1.3 ppm or 1300 ppb Action Limit ppm or 15 ppb Comments Measured at the tap Must be met in 90% of samples If exceeded must provide corrosion control treatment and public education 11

12 Rules and Regs Review Question: A public water system has a least service connections and/or serves at least people for days out of the year? Answer: 15, 25, 60 12

13 Rules and Regs Review Question: What is the maximum turbidity levels for surface water systems? Answer: Never exceed 1.0 NTU, and 95% of samples must be below 0.3 NTU 13

14 Rules and Regs Review Microbiological Contaminants: Total Coliform Rule (Total Coliforms, Fecal Coliforms, and E. Coli) Less than 40 samples per month; no more than one positive for total coliforms If 40 samples or more per month; no more than 5% positive Note: The total number and location of samples is based upon the population served and a system-specific sampling plan 14

15 Pump Review Stuffing Box Contains: Packing or mechanical seal Controls leakage Mechanical seals are used for high discharge head Lantern ring Allows water to flow evenly through the packing Packing glands 15

16 Pump Review Question: Do bowls add volume or pressure? Answer: Pressure Multi-stage Stages add pressure not volume 16

17 Pump Review Question: What is considered to be the heart of the pump? Answer: The impeller Remember: Water is thrown away from the impeller, not cupped 17

18 Pump Review Couplings Connect shafts of different diameters Transfer energy Allow for sight misalignment Absorb starting torque 18

19 Pump Review Pump/Motor Maintenance Follow manufacturers recommendations Avoid over greasing Grease acts like an insulator, holding in heat Most common motor speeds 1800 rpm 3600 rpm Oil Drip rate 5 drops/min. 19

20 Pump Review Cavitation Sounds like pumping rocks, caused by air entrapped in volute case, air implodes causing damage to pump Piping Eccentric reducer Suction side Concentric increaser Discharge side

21 Safety Review Question: What are the different types of soil and which one is the most unsafe? Answer: A, B, and C A is the most stable (safest) and C is the most unstable soil (most unsafe) 21

22 Safety Review Question: In a trench or excavation, means of egress is required when? Answer: When a trench is 4 feet or more in depth Exits must be provided at least every 25 feet Ladders must extend 36 inches above the trench 22

23 Safety Review Question: What is the minimum distance spoil and other equipment must be placed from the edge of the trench or excavation? Answer: Two feet 23

24 Safety Review Flag Person Placed a minimum of 100 feet in front of work site Trained and certification card Oxygen Deficient Atmosphere 19.5 percent MSDS Holds information regarding hazardous substances 24

25 Safety Review Chemical Safety For acid solutions pour acid into water To neutralize acid spills use Sodium Bicarbonate (Baking Soda) Laboratory Safety Never pipet liquids with your mouth, use a rubber suction bulb Use PPE Safety glasses, rubber gloves, apron, ect. 25

26 Safety Review Chlorine Safety Repair Kits Kit A is for 150 lb. Cylinders Kit B is for Ton Containers Leaks Most occur at the valve Can cause greenish or reddish color pipe Use ammonia solution to check for leaks 26

27 Security Review Question: Why are vulnerability assessments conducted? Answer: Identify threats to the water system Determine the likelihood that a threat may materialize Calculate the consequences of losing part or all of the water systems assets 27

28 Security Review Question: What are the three stages of threat management? Answer: Possible Credible Confirmatory 28

29 Security Review Some of the critical components of a water system include the systems water sources treatment plants distribution system communications power sources NOTE: System inspections should be conducted frequently and randomly 29

30 Security Review To have an effective ERP, it must address four important phases: 30

31 O&M Review Water Hammer A condition that occurs when a valve is rapidly closed or opened Causes the pressure to increase and decrease back and forth very quickly Sounds like someone hammering on a pipe Can damage pipes, causing them to burst or come apart 31

32 O&M Review Thrust Blocking Concrete mass between a fitting and the soil Keep fittings from moving and coming loose or apart from the force of the water pressure in the pipe

33 O&M Review Head Loss Friction from various factors can slow down the velocity of water Can be caused by valves, bends, pipe roughness (C-Factor), etc. 33

34 O&M Review C-Factor A factor or value to indicate the smoothness of a pipe The higher the C value, the smoother the pipe To calculate measure the flow, pipe diameter, distance between two pressure gauges, and the friction losses between the gauges 34

35 O&M Review Cross Connections Any (actual or potential) connection between a potable and an unapproved source The problem with a cross connection is that backflow can occur Backflow is the flow of any water, foreign liquids, gases, or other substances back into a potable water system 35

36 O&M Review Two conditions that can cause backflow are: Back Pressure A condition in which a pump, elevated tank, boiler, or other means result in a pressure greater than the supply pressure Backsiphonage A condition in which the pressure in the distribution system is less than atmospheric pressure 36

37 O&M Review Question: What is the best protection against cross connection? Answer: Air Gap An open vertical drop, or vertical empty space, that separates a drinking (potable) water supply to be protected from another water system Minimum of one inch or twice the diameter of the incoming pipe whichever is greater 37

38 O&M Review Types of backflow prevention devices: Air gap separation Double check valve Reduced-pressure principle (RPP) device Pressure vacuum breaker Atmospheric (non-pressure) vacuum breaker 38

39 Gate Valve Used for stopping or isolating O&M Review Valves Should be either all the way open or all the way closed Butterfly Valve Used for non-critical throttling applications Check Valve Stops back-flow in the piping Operates automatically Should be located on the discharge side of a pump 39

40 Gate Valves

41 Butterfly Valves

42 Check Valves

43 O&M Review Air Vacs & Drains Use a #14 mesh screen for air vents and air vacuum release valves #14 mesh = 14 squares/inch Use a #4 mesh screen for overflow and drain lines #4 mesh = 4 squares/inch Remember: an air vac vent pipe needs to be above the flood line 43

44 Chemical Feed Review Pathogens Disease causing organisms Types: Bacteria, Viruses, Protozoa Viruses and cysts are more resistant to disinfection than are most bacteria 44

45 Chemical Feed Review Disinfection Killing pathogenic organisms Sterilization Killing all organisms Chlorine kills bacteria by: Penetrating the cell wall and attacking a critical cell enzyme 45

46 Chemical Feed Review Calcium hypochlorite or HTH White granular powder 65% available chlorine Sodium hypochlorite, NaOCl Clear yellowish liquid 5 to 15% available chlorine Chlorine Dosage Formula Cl Dose = Cl Demand + Cl Residual 46

47 Chemical Feed Review Chlorine residual test results provide the following information: Whether a residual exists Type of residual Amount of residual DPD A method of measuring the chlorine residual in water Turns water pink or red 47

48 Chemical Feed Review Factors Affecting Chlorination Concentration Contact Time Temperature ph At lower temps bacterial kill tends to be slower Addition of chlorine lowers ph Substances in the water Masks or shields 48

49 Chemical Feed Review Chlorine Maximum Withdrawal Rates Ton containers 400 lbs/day 150 lb. cylinders 40 lbs/day 49

50 Chemical Feed Review Chlorine Container Fusible Plugs Melt at 157 to 165 degrees Fahrenheit 150 lb. Cylinders One mounted on valve Ton containers Three on each end 50

51 Chemical Feed Review Fluoridation The purpose is to maintain the optimal level of fluoride needed by children to develop resistance to tooth decay MCL = 4.0 mg/l The optimal concentration to achieve the maximum benefits of fluoridation is 1.0 mg/l SPADNS is the field test used to check for daily fluoride concentrations 51

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