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Home My WebLink AboutDDW-2025-002538Water Treatment Operation & Maintenance Exam Review Terminology GPM= gallons per minute MGD= million gallons per day TTHM= total trihalomethane PSI= pounds per square inch NTU= Nephelometric Turbidity Unit mg/L= milligrams per litre or ppm= parts per million Feet of Head Pathogenic Disease causing organisms Includes Viruses, Protozoa, or Bacteria Causes diseases such as typhoid, cholera and dysentery Organisms that don’t cause disease are non-pathogenic Purpose of Treatment Process Screens Remove debris Pre-chlorination Kills pathogens, controls taste and odors. Possible problems with DBP’s Use UV or Ozone instead Chemicals Assist with the process Flash mixer Mixes chemicals with water Coagulation/flocculation Slowly mixes the chemical and particles together. Intakes & Screens Multiple inlet intake structures allows operators to pull from depth of better quality Should prevent large debris & fish from entering treatment plant Should be designed to handle flows Manually cleaning screens for small amounts of debris Turnover cause mainly by change in water temperature & density Thermocline Epilimnion- upper layer that circulates warm water where dissolved oxygen concentrations are moderate to high Thermocline- separates upper an lower layers Hypolimnion, a cold, deep- water, non-circulating layer in which oxygen is low or absent Pre-sedimentation Removal of debris Helps control impact of changing raw water Impoundments are types of pre-sedimentation systems Aeration Removes dissolved gases Removes dissolved metals such as iron Releases volatile chemicals Coagulation/Flocculation Zeta Potential The repelling force that keeps particles separated Coagulation Is the adding & rapid mixing of chemical coagulants in water to reduce turbidity prior to filtration Is a chemical reaction between coagulant, turbidity, & alkalinity. Neutralizes negative (-) charges Flocculation is a process that form floc to settle out impurities in the water & reduce turbidity prior to filtration Floc grows with the collision of the particles Troubleshooting Paddle speed- slow speed floc will settle prematurely Velocity through basin Short circuiting Primary Coagulants Aluminum sulfate Ferrous sulfate Ferric sulfate Cationic polymer Calcium hydroxide Calcium oxide Sodium aluminates Coagulant Aids Calcium hydroxide Calcium oxide Sodium aluminates Bentonite Calcium carbonate Sodium silicate Anionic polymer Nonionic polymer Sedimentation Allows solids to settle out before filtration Sedimentation - With Settling Tubes As required by drinking water rules Sedimentation - Without Settling Tubes 2 hours detention time WLR (weir loading rate) <20,000 g/d/ft weir length Head on rectangular weir is measured from crest to top of water on weir plate 0.5 fpm velocity 8 to 12 ft depth Sedimentation Sedimentation Troubleshooting Short circuiting Temperature Working properly determined by the measurement of turbidity in compared to turbidity out. Wind currents Velocity Increase in flow Floating materials Sludge removal Sludge accumulation Noisy drive chain Tube Settler Filtration Systems Conventional – Pressure Filters Screens Pre-chlorination Chemicals Flash mixer Coagulation/ flocculation Sedimentation Filtration Post chlorination Chemicals Clear well Filtration Systems Conventional Treatment Screens Pre-chlorination Chemicals Flash mixer *Coagulation, Flocculation, Sedimentation, & Filtration Post chlorination Chemicals Clear well Non-conventional  Direct filtration *No sedimentation Slow sand filter *No: Chemicals Flash mixing Coagulation Flocculation Sedimentation Filtration Removes small contaminants Bacteria- Salmonella, E. Coli Protozoan- Giardia, Cryptosporidium Virus- Hepatitus A, Rotavirus Types Mechanical filter Absorption filter Slow sand Rapid sand Mixed media Highest rate of flow Water flows through the filter by percolation Head loss gauge measures pressure drop as water passes thru the filter Filtration Rates Terminal Head Loss water can no longer be filtered Recommended flow rates are 15 to 20 GPM per square foot Closing inlet valve & measure drop in the water level over time you can determine flow thru filter Too large of floc can cause the filter to clog at a rapid rate Filter Loading rates are defined as gallons of water applied to each square foot of filter surface area Filter Media Types Sand Anthracite Garnet Granular Activated Carbon Green Sand Measured by sieve analysis to determine size Multimedia Filter - Sand - Garnet - Coal Filtration Removes small contaminants Bacteria Protozoan Virus Types Mechanical filter Absorption filter Slow sand Rapid sand Mixed media Highest rate of flow Water flows through the filter by percolation FILTRATION Trouble shooting Method of determining flow through a filter without a meter. Measure the rise or fall of the water in the filter over time Used for removal of Giardia & Cryptosporidium Aeration Dissolves gases Dissolves metals Removes volatile chemicals FILTRATION Trouble shooting Mud balls Improper surface washing or backwashing Air binding Cold water Negative pressure head in lower filter Cracking Septic smell Disinfection Process to kill or inactivate most pathogens in water. There are several ways to disinfect Chlorine is most popular method because of cost and it leaves a residual throughout the system UV Ozone- doesn’t leave a measurable residual in system Breakpoint Chlorination Graph Chlorine smell would indicate you need to add more to reach breakpoint Disinfection By-products TTHM- Total Trihalomethanes Adsorption where molecules collect & adhere to a surface of an adsorbent solid (GAC) would help reduce TTHM’s Combination of chlorine and organics Warmer temperatures and pH form THM’s faster THM precursors would indicate THM forming throughout the system Aeration & Clarification can remove THM precursors Organic Matter TTHM Total trihalomethanes MCL = 80 ppb (0.080 mg/l) HAA5 Haloacetic acids MCL = 60 ppb (0.060 mg/l) Reduction and removal through: Absorption Aeration Oxidation Clarification Under Drains Used for backwashing Collects the filtered water Keeps the media bed in the filter. Backwash Open backwash valve slowly Backwash is based on: Increase in Effluent Turbidity Head Loss Filter Run Times determined by plant (many use 36 hrs) Backwash duration depends on amounts of sludge & debris in filter Typical Backwash Rate: 15 to 20 gpm/sq.ft. Filter Head Loss Gauge Used to measure drop in pressure thru filter Terminal head loss = No water flowing Surface Washer Mudballs and surface mats are reduced Sludge Collectors Fix noisy drive chains by tightening and aligning the chain & casing 3 Most Important Monitoring Parameters For Safe Drinking Water Bacteria Turbidity- operator has most control over Chlorine residual Jar Testing Duplicates the treatment plant processes such as detention time, mixing conditions & settling conditions Helps provide optimal dosages Helps optimize coagulation process Floc remaining longer than 15 to 20 minutes probably won’t settle out Water Hardness Caused by salts of calcium & magnesium (bicarbonate, carbonate, sulfate, chloride & nitrate) Causes formation of soap curds Increased use of soap Deposits in boilers & fixtures Damages industrial processes Water Hardness & Corrosion Objectionable tastes Magnesium leaves black stains Galvanic Corrosion cause by dissimilar metals in a drinking water system Hardness test uses EDTA titrant Expressed as mg/L CaCO3 Soft water considered as 0 to 50 mg/L of CaCO3 High dissolved CO2 would increase corrosion Corrosion Electrochemical phenomenon observed as red water Calcium carbonate saturation used for corrosion control Measurements: Langelier index Positive number: Deposit Negative number: Corrosive Metal coupons used to measure corrosiveness of water – determined by weight loss of coupon Adjustments can be accomplished by: Chemicals which increase or decrease the depositing, or Sequester the problem with the use of polyphosphates C-Factor Indicates the smoothness pipe material The higher the C value, the smoother the pipe. To calculate measure flow, pipe diameter, distance between two pressure gauges, and the friction losses between the gauges. Tuberculation reduces C value PVC has higher C- factor than concrete Head Loss Friction head loss: caused by valves, bends, pipe roughness, etc. Water hardness caused by calcium & magnesium Coefficient tests can indicate whether or not friction losses are increasing Galvanic corrosion can happen when connecting brass to steel FRICTIONAL HEADLOSS Energy used up by water movement Two Conditions that affect head loss: 1. Roughness 2. Velocity . Two Conditions that affect Roughness: 1. Age – Condition 2. Type of pipe Materials Iron Consumer complaints Can cause stains on laundry & fixtures Formation of iron bacteria that form slick slimes on pipe walls Taste and odor problems Reacts with chlorine increasing use Removed thru aeration and filtration Iron & manganese react with dissolved oxygen forming insoluble compounds Polyphosphates & flushing reduce iron deposits Turbidity- NTU’s The following is the most frequent method used to water quality & the cloudiness of the water Uses light to measure The higher the NTU, the dirtier the water, the more possibility of micro- biological contamination NTU= Nephelometric Turbidity Unit Turbidity Physical characteristic of water making it appear cloudy. Caused by suspended matter. The most monitored treatment of water for quality. The greatest control factor in treatment of water. Increased influent turbidity means an increase in chemicals Masks pathogens from disinfections. Particle Counter The method used to measure the cloudiness of the water – the amount of particles and the size of particles. The dirtier the water, the greater the possibility of microbiological contamination. Alkalinity A measurement of the water’s capacity to neutralize an acid Alkalinity is determined by titrating to an end point with a pH meter or the use of the methyl orange test Use sulfuric acid to perform test Affects the coagulation process The higher the alkalinity, the better the floc formation pH pH: expression that refers to the basic or acidic conditions of the water pH is measured on a scale from 0 to 14. Less than 7 is more acidic, greater than 7 is more basic or higher alkalinity. 7 is neutral. PVC pipe is least affected by acidic water Reinforced concrete pipe would most likely corrode in acidic water Corrosiveness on pipes can be detected by plotting Baylis Curve or Langlier Index Weight of metal coupons used to determine corrosiveness A negative number on Langlier Index would be corrosive pH Any substance that releases HYDROGEN IONS (H+) when mixed with water is acidic (0-6) Any substance that releases HYDROXYL IONS (OH-) is a base (8-14) Alkalinity changes will affect the coagulation process pH is measured by use of a PROBE OR A COLORIMETRIC METHOD. SIGNIFICANCE: Affects chlorination, coagulation, softening, and corrosion CO2 – Carbon dioxide reduces the pH Temperature Characteristics of Temperature The colder the water, the more dense. The colder the water, the less activity. Higher disinfection concentration is required in cold water. Low temps decrease the rate of floc settling F (Fahrenheit) C (Celsius) Main impacts Affect to speed of biological and chemical reactions Affect to rate of biological decomposition Changes to chlorine demand Temperature Low temperatures the bacteria kill rate is lower Chlorine residual will remain longer in cold water Warm water will cause bacteria to bloom Calcium Carbonate will form more rapidly in hot water Temperature drops would cause carryover in sed. basins Chemicals Chemical Storage Cool, dry place Away from general traffic Non-treatment chemicals Spillage control – clean plan Empty drum disposal According to manufacturer’s recommendation Chemical Compounds Aluminum sulfate Ferrous sulfate Ferric sulfate Cationic polymer Calcium hydroxide Calcium oxide Sodium aluminates Calcium Carbonate Aluminum Sulfate (Alum) Part of coagulation/flocculation process & creates the floc An anhydrous acid Affects skin and mucous tissues Need goggles, face shields, dust mask, gloves, boots, rubber apron, clothing to protect skin & proper ventilation MCL for atmosphere 15 mg/cm for 8 hours When added to water: Dissolved Sulfate increases Alkalinity decreases pH decreases MCL in finished water is 450 mg/l Alum Alum is a mild corrosive Never use the same conveyor system for alum and quicklime Potential for explosion pH below 5 floc won’t form properly Ferric Chloride Is a very corrosive material Should prevent splashing Use eye protection, rubber gloves, and protective clothing When spilled on skin, flush with large amounts of water Chemicals Corrosion Control Calcium hydroxide Hydrated lime- increases pH Sodium hydroxide Caustic soda Softening Calcium oxide Quicklime Sodium carbonate Soda ash Fluoridation Sodium fluorosilicate Sodium fluoride Fluorosilicic acid Hydrofluoric acid SPADNS test for fluoride Chlorine Gas is heavier than air Have eyewash/shower available Most leaks occur around control valve Cylinder liquid form expands 460 times When changing cylinders, shut gas off at cylinder first, evacuate lines Produces hydrochloric acid mixed with moisture Use rubber gloves & ventilate Should practice response once per year Inspect daily for leaks in system Higher alkaline = more chlorine Chlorine Leaks Put on SCBA Turn on ventilation fan Have help standing by Three Forms of Chlorine POWDER 65%- HTH (High Test Hypochlorite) Calcium Hypochlorite LIQUID-Sodium Hypochlorite *Bleach 5% *T-Chlor 15% GAS 99.9% *extremely corrosive with water/humidity *compressible *changes to liquid at 82 psi *68 deg. F *2.5 times heavier than air *greenish-yellow color * Must meet NSF approval Calcium Hypochlorite & Quicklime Calcium Hypochlorite Can create heat & oxygen to start a fire HTH- High Test Hypochlorite Quicklime Extremely caustic material Reacts violently with water Reaction can cause fire or explosion Store totally dry area Do not allow to mix with alum Chloramines Formation of chloramines is a chemical reaction The reaction is between hypochlorous acid (or aqueous chlorine) with ammonia. Formation of chloramines weakens the disinfecting strength of chlorine Chloramination Cloramines are a reaction between applied chlorine and ammonia When done intentionally it can reduce tastes and odors Chloramines are a weaker disinfection than chlorine DPD Method of measuring chlorine residual in the water Testing agent turns chlorinated water a pink color. More intense color, higher residual. DPD= N,N-diethyl-p-phenylene-diamine Fluoride Victims exposed to large amounts should me removed from area Operators should know the hazards contained in MSDS Can cause dental stains & mottling of teeth SPADNS test to analyze fluoride levels Over Feeding Fluoride Can Mottle Teeth Caustic Soda Safety Strong caustic alkali and very hazardous Very reactive Dissolves human skin Generates heat with when mixed with water Reacts with amphoteric metals generating hydrogen gas which is flammable or explosive Use special precautions when handling Chemical Safety for Acids Chemicals cause visible destruction or irreversible damage to skin tissue at the point of contact Swallowing can damage esophagus & stomach. Wear personal protective equipment Flush affected area with clean water Use sodium bicarbonate to neutralize acids Add acid to the water Polymers Used as coagulant and filter aids Keep polymer dust off floors Will create very slippery surfaces when on floors Use inert, absorbent material such as sand to clean up spills Polymers Filtration aid Not enough: Rapid turbidity break through Too much: Rapid increase in head loss Potassium Permanganate Strong oxidizing agent, use caution Turns water pink Will react easily with organic materials Will ignite when in contact with antifreeze, sawdust compounds and many other materials All lubricants & fuels are potential fire hazards Store separately from other chemicals in a cool dry location Use dust masks and rubber gloves when handling & for cleaning up Used for taste & odor, TTHM control, reduces Iron, Hydrogen Sulfide (rotten egg smell) & Manganese Explosions Don’t use sawdust to absorb liquids Powder activated carbon is the most volatile powder Methane is the most common combustible gas Activated Carbon Used for taste & odor problems Is considered the most volatile powder Keep away from Cl2 compounds and KMnO4, possible spontaneous combustions The main problems are dust and fire control Will burn with intense heat, and without smoke or visible flame Keep electrical equipment clean Carbon dust can cause short-circuit fires Use explosion-proof electrical equipment Used prior to chlorination because they react with each other Taste & Odor Activated Carbon & KMNO4 are chemicals used Threshold Odor Number (TON) is a unit of measure for odors in water & should be conducted at 60 deg. Celsius Water devoid of oxygen produces odor and anaerobic bacteria growth Sludge accumulations could cause problems Algae Control Chemical Copper Sulfate Indicators that affect copper sulfate: Alkalinity Type of algae Temperature Nitrite – Cause & Effect Cause Large concentration of fertilizers. Effect Blue-baby syndrome High Nitrate Levels MCL 10 mg/1 5 mg/1 – quarterly monitoring Nitrate turns in nitrite and replaces oxygen in blood. Thus babies and immuno-deficient individuals are affected. Fusible Plug Safety Device Made out of lead Melts between 160 to 165 degrees 150 lb. Cylinder Valve Sampling Grab samples taken in instantaneous conditions at certain times & locations Composite Sample Bacteriological Sampling Procedures If sample is OK, this only indicates that water was safe at point of sample Coliform is an indicator of bacteria presence Sample should be transported as soon as possible in a cool container with ice pack Routine bacti’s should be taken at the customers tap at various points that represent the entire system Not smooth nosed Bacteriological Sampling Procedures Should allow sample tap water to run several minutes or as long as necessary to clear service line Sampling bottle/bag should be filled to just above fill line or 1 inch from top Results are meaningless if sample is contaminated Sample identification cards need to filled out completely Should be sterilized by lab Sodium Thiosulfate Dechlorination agent in bacteriological sample container Coliform Coliform= a group of bacteria found in the intestines of warm blooded animals & also plants, soil, air and water Total Coliform= a measurement that shows if coliform bacteria is present in a water system & are an indicator organism Fecal Coliform= a specific class of bacteria coming from animal intestines. If sample is coliform positive, a fecal coliform test is performed. GWR December 1, 2009 TC+ bacterial Samples Requires Triggered Source Water sample (TSW) Of all sources that were in operation at time of +TC sample Email on sources not sampled – not running Test for fecal coliform GWR continued 5 addition samples if first TSW is Fecal+ 2 or more sources requires you to submit new sample site plan Correct significant deficiencies within 120 days Sanitary Surveys Performed By Executive Secretary shall ensure a sanitary survey is conducted at least every 3 years Division of Drinking Water DEQ District Engineers Local Health Departments Forest Service Engineers Utah Rural Water Association staff Consulting Engineers Others authorized by Executive Secretary Aesthetics Means attractive or appealing. With respect to water it means taste, odor, or coloration of the water. Things that affect this are extreme hardness or high total dissolved solids Effects range from bad smell and poor taste to causing stains on laundry and/or fixtures Electrical Motor Clean dust from a motor with compressed air. Measure speed with tachometer Auxiliary motors can be used in emergencies Brake HP is amount of HP supplied by the motor to the pump Circuit Breaker Opens or closes the electrical circuit to motors Function as overload device Opens automatically when an overload occurs to protect circuit Electric Motors Upon start up an electric motor will develop a load to turn the pump shaft and impeller Torque causes motor to draw a high amperage To change rotation on 3 phase, switch any 2 leads Voltage imbalances cause 3 phase motors to overheat & burn out the insulation Tachometer used to determine speed of motor/pump Volt – Ohm Meter Volts Measure of the force of electrons Set the volt meter at a higher setting than the voltage being measured. Ohms Measurement of resistance Amps Measurement of the flow of electrons Transformer The purpose of the transformer is to increase (step up) or decrease (step down) voltage. Confined Spaces Carbon dioxide will settle near floor Blowers are the most effective means to reduce atmospheric hazards Ventilate until proper oxygen levels are reached (minimum19.5%) Security Deter Detect Delay Respond Safety Security Reservoir sites Sources Main Offices Vehicles Vaults Distribution Systems Looped systems have continuous flow & less water quality problems Water quality problems could indicate a closed valve or partially open Leak surveys done at night Water mains 10 Feet horizontal distance from sewer main Water main and sewer mains must cross at least 18” of separation Water line is on top Water & sewer not installed in the same trench. Leaks will get worse not better Maintenance Records Why keep maintenance records? Develop preventative maintenance program Prolong life of equipment Maps Maintain backup equipment Reduce liabilities Improve customer service Ground Water - Wells Water bearing formation called an aquifer New & Repaired Water Mains Pressure test Disinfected in accordance with AWWA standard C651 Must be disinfected with some type of chlorine Tablet or a solution are typically used Chlorine must be flushed with potable water Take chlorine residuals Must take bacteria samples Water Distribution Systems Operation and Maintenance Water main design Distribution system pressures 20 psi at all times Peak instantaneous flows Minimum Water main size 8 inch with fire hydrants Unless you have an engineer signature to buy off on it 4 inch without fire hydrants New Minimum PSI Standards Maintain minimum of 20 psi at all times For Construction after 3/1/06 *20 psi during fire flow *30 psi during peak instantaneous demand *40 psi during peak day demand Thrust Blocking Thrust Block - a concrete mass cast in place between a fitting and the undisturbed soil at the side or bottom of the pipe trench. Purpose is to keep fittings from moving & either coming loose or apart from the force of the water pressure in the pipe. Needs to be centered on the thrust force Water Storage Reservoir Provides a volume of water to the water system during average and peak demands Provides adequate pressures throughout the water systems Covered to prevent bacti & algae growth Reserve storage Fire protection Storage Reservoirs 2 categories of paint- long life and short life Frequent pumping & changing depth can reduce freezing Sandblasting is recommended to prepare inside for painting, inspect every 3 to 5 years Stagnant water causes quality problems They’re most susceptible to water quality degradation from external sources Parts of a Well Pumps from a geologic formation called an aquifer When water passes through porous layers of soil it’s called percolation Sanitary seal – prevents contamination from entering Well casing – pipe placed inside well to keep it open Grout – mixture of cement, water and sand pumped between the casing & the drilling hole (annulus) Parts of a Well Well Screen – unrestricted water flow and small enough to stop sand from entering Gravel pack – aids screen in filtering sand. Wire to Water Efficiency Energy required to overcome pump inefficiencies The combined efficiency of the pump and the motor together. Also called the over all efficiency. Water HP HPx100 = % Wire to Water Efficiency Motor HP (Flow, gpm) (Total Dynamic Head, ft) (0.746 kw/hp) (100) = % WWE (3,960) (Electrical Demand, kilowatts) Cavitation Main cause of losing pump suction Sounds like pumping rocks or pinging Vibration & popping noises caused by low pressure in volute Generally caused by vapor bubbles Vapor bubbles implode causing damage to pump Volute case needs to be full of water Prevented by having adequate suction pressure and proper bowl depths Cross Connections Cross connection: a connection between a potable & an unapproved source. Caused most disease outbreaks Two Types of Backflow *Backsiphonage: backflow caused by a negative or below atmospheric pressure in a water system where a vacuum exists such as draining as system (fire fighting can cause) *Backpressure: when users pressure is higher than the system pressure Approved assemblies are used to keep contaminants out the drinking water system Protection established by degree of hazard Air Gap- Safest Method A physical break between the end of a pipe and an open vessel flood rim •Minimum of 1” or two times the diameter of the pipe. Backflow protection •Backsiphonage Hazard •High degree or health risk Required on all sewer, wastewater or sludge connections Meter Sizing Considerations Pressure at the service connection Highest fixture in the building being served Any back flow prevention device A 5/8 inch meter should be tested every 5 to 10 years. Meter should not have more than 20 psi of head loss. In absence of a flow meter on a filter you can close the inlet valve and measure the drop over time. AWWA C651 – Water Mains Methods Tablet or granular – 25 mg/l – 24 hours Continuous Feed – 10 mg/l after 24 hours Fill main with water Flush out debris Fill with chlorinated water AWWA C651-05 Final flushing Clearing main of heavily chlorinated water Disposing chlorinated water Discharge can cause damage to the environment Neutralizing agents Sulfur dioxide, sodium biosulfates, sodium sulfide, sodium thiosulfates, ascobic acid Flushing at 2.5 fps Scour the insides of the pipe. AWWA C651 Water Mains Continued Slug method 3 hour exposure of not less than 50 mg/l Start with 100 mg/L and test at intervals on pipe If residual drops below 100 mg/L move equipment Procedure existing water mains Positive pressure during repairs Swabbing Flushing Slug chlorination 300 mg/l – 15 minutes Sampling – to prove procedure effectiveness Bacteriological Testing Standard Conditions AWWA C651-05 2 samples - 24 hours apart One set collected every 1200 feet Plus one set from ends of main At least one on each branch Bacteriological Testing Special Conditions Trench water entered Excessive quantities of dirt Water stand for 16 hours before 1st test Sampling procedures No hose No fire hydrant What does your ordinance say about testing Orem’s Ordinance Pressure Testing New Water Main Pipe should sit idle for at least 24 hours Should be done at 150 psi Or 1.5 times the normal pressures Duration 4 Hours Valves Gate Valve: Isolation, should be either all the way open or all the way closed (least amount of head loss) Air and vacuum relief: allows air in and air to escape. Altitude valve: opens when system psi drops below a certain pressure and closes when the reservoir reaches a predetermined level. Glove valves used for flow & pressure regulating Gate Valves - Isolation Altitude Valve – good for regulating tanks Pump Control Valves Minimizes water hammer Starts & stops on a closed valve Valves Pressure Sustaining/Reducing: maintain either upstream or downstream pressures depending on the position of the pilot screw. Need periodic service & maintenance Butterfly Valves - Higher resistance to flow Operates easily & quickly They cost less than gate valves Used for flow control Ball & Plug Valves Sluice Gate & Sleeve Valves Check Valves Permit flow in one direction Swing Checks Spring loaded silent checks Water Hammer Occurs when a valve is closed quickly or pump shuts down and causes the water pressures to rise and fall rapidly. Sounds like some hammering on pipe. Can damage pipes, causing them burst. Meter Sizing Considerations Pressure at the service connection Highest fixture in the building being served Any back flow prevention device A 5/8 inch meter should be tested every 5 to 10 years. Meters should not have more than 20 psi of head loss. Meters one inch and smaller shouldn’t have more than 15 psi of head loss Venturi meter is not a prime mover Meter Accuracy Worn meters under register & give the customer free water Over time a worn meter will cost the water system revenue. Formula: Meter Accuracy= (Meter,GPM)(100%)/Volume,GPM Compound meters are used for low to intermediate flows & occasionally for high flows Positive Displacement Meter Nutating disk: nutating means nodding. When the water flows the disk rotates. Piston Meter Displacement type Water flows into a chamber and displaces piston Oscillating circular motion moves meter Higher head loss than nutating disk Velocity Meter Propeller, Venturi, insertion type, and most electronic types Rotors or propellers are turned be velocity of meter Air Release Valves (Air Vac) – air in & out Should be placed at high points in the water system. Outlet should be screened about 12” min. above ground CombinationAir ReleaseAir Vacuum Line Collapse Caused by not opening a downstream valve before they began sucking water from the other end A vacuum developed before they realized what happened and the pipe pancaked The pipe is the main transmission line to supply water for the City of Folsom HYDROPNEUMATIC TANKS Frequent on/off cycling indicates water logged tank Operate by applying air pressure to tank Tank levels controlled by pressure switches to pumps Air leaks can cause pumps to run continuously 1/3 to 2/3 air to water ratio limiting storage capacity WATER AIR COMPRESSOR PUMP PSI PUMP CONTROL BLADDER OR DIAPHRAGM PSI AIR RELIEF OPERATING LEVEL WATER LEVEL AT MINIMUM OPERATING PSI Acronyms Forms of expressing a flow of water over a period of time: GPM Gallons per minute MGD Million gallons per day CFS Cubic feet per second Acronyms PSI = pounds per square inch The pounds of force on a given area. The area is expressed in a square inch. 60 pounds per square inch, or 60 PSI 60 pounds 1 inch 1 inch Acronyms Methods for measuring chemicals or other constituents in drinking water ppm Parts per million Refers to 1 gallon or lb. of a chemical in 1 million gallons or lbs. of water mg/l Milligrams per liter The same measurement as ppm expressed in metric measurements Acronyms PVC, PE, ABS- refer to chemical composition of pipe Methods for measuring chemicals or other constituents in drinking water ppb Parts per billion The measure of 1 gallon or lb. of a chemical in 1 billion gallons or lbs. of water ug/l Microgram per liter The same measurement as ppb expressed in metric measurements 1000 ppb or ug/l = 1 ppm or mg/l Example: 80 ppb is the same as 0.080 mg/l Definitions Toxic A substance that is poisonous to a living organism. Potable Water that does not contain objectionable pollution, contamination, minerals, or infective agents and is satisfactory to drink. Culinary Fit for human consumption. Action Level: Required actions if lead and copper standards are exceeded: MCL Lead – 15 ppb, or 0.015 ppm Copper – 1300 ppb, or 1.3 ppm Fire Hydrants Dry barrel hydrant used in areas susceptible to freezing. Drain hole allows water to drain from barrel so water won’t freeze and crack the hydrant. Hydrant bury is the distance below the ground to the main connection. Because of increased population growth and scaling of pipes, hydrant flow tests should be performed periodically. If the cut stake for a fire hydrant is marked AC- 4.25@ and the hydrant is 7 ft. 6 in. tall, how high will the top be above the finished grade? 7’ 6” convert to decimal 7.5 – 4.25 = 3.25 3.25 is the answer 7’6” 4.25’ ? ft. C - 4.25 Thrust Blocking Thrust Block - a concrete mass between a elbows, crosses & tees in undisturbed soil at the side or bottom of the pipe trench. Keeps fittings from moving & either coming loose or apart from the force of the water pressure in the pipe. Thrust anchors – used when thrust blocks cannot be used Restrained fitting – use of clamps or anchor screws on fittings Tie rods – used on mechanical joint fittings that a located close together Should be calculated & designed properly Thrust Blocks Water Loss Affected by: leaks, pressures, efficiency of the meter maintenance, attention given to leak reduction, & unauthorized use of water Some systems 10% of the water produced Other systems not until 20% Lightning Arrestor Becomes a low resistance conductor to ground when the line voltage exceeds a predetermined amount Used to protect equipment from lightning strikes. No device made to protect against a direct hit. Screen Sizes #14 mesh for air vents and air vacuum release valve Air vac vent pipe above the flood line #4 mesh for overflow and drain lines #14 mesh = 14 squares per inch #4 mesh = 4 squares per inch #14 #4 Electrolysis Decomposition of material by an outside electric current Electric current caused by movement of water in the line Cathodic protection installed to prevent Tanks – Cathodic Protection