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CWEA ECI Grade 1 practice questions

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1) What does 5% w/v mean?
  1. 5 grams of solute dissolved in 100 mL of solution
    w/v stands for weight/volume. It is used for solid solutes dissolved in liquid solvents.
    • Weight refers to the weight of the solute and is measured in grams.
    • Volume refers to the final volume of the solution and is measured in mL.
    Therefore, 5% w/v means 5 g of solute for every 100 mL of solution.
  2. 5 grams of solute dissolved in 100 mL of solvent
  3. 5 mL of solute dissolved in 100 mL of solution
  4. 5 mL of solute dissolved in 100 mL of solvent
2) 0.5 mol of solute is dissolved in 250 cm³ of solution. What is the concentration in mol/dm³?
  1. 0.002 mol/dm³
  2. 2 mol/dm³
    First, we need to convert cm³ to dm³. Since one dm³ is a thousand times larger than one cm³, we need to divide the number of cm³ by 1,000: 250/1,000 = 0.25 dm³ Now we can work out the concentration. The concentration formula is: concentration = amount of solute/volume Inserting the values into the formula gives: concentration = 0.5/0.25 = 2 mol/dm³
  3. 12.5 mol/dm³
  4. 125 mol/dm³
3) A hydrogen chloride solution has a concentration of 0.5 mol/dm³. Given that the molar mass of hydrogen chloride is 36.5, what is the solution's concentration in g/dm³?
  1. 0.065 g/dm³
  2. 18.25 g/dm³
    To convert moles to grams: moles × molar mass = grams This formula can also be used to convert mol/dm³ to g/dm³: mol/dm³ × molar mass = g/dm³ Inserting the values from the question into this formula gives us: 0.5 mol/dm³ × 36.5 = 18.25 g/dm³
  3. 36.55 g/dm³
  4. 73 g/dm³
4) Calculate the volume of a 0.5 mol/dm³ solution that contains 1 mol of solute.
  1. 0.5 dm³
  2. 0.75 dm³
  3. 1 dm³
  4. 2 dm³
    The concentration formula is: concentration = amount/volume We can rearrange this formula to: volume = amount/concentration Inserting the values into the formula gives us: volume = 1/0.5 = 2 dm³
5) 8.0 g of magnesium oxide contains 4.8 g of magnesium and 3.2 g of oxygen. If the atomic mass of magnesium is 24 and the atomic mass of oxygen is 16, what is the empirical formula of magnesium oxide?
  1. MgO
    To find the empirical formula, start by converting the masses of each element into moles. moles of magnesium = mass/atomic mass moles of magnesium = 4.8 g/24 moles of magnesium = 0.2 moles of oxygen = mass/atomic mass moles of oxygen = 3.2 g/16 moles of oxygen = 0.2 Since there are 0.2 moles of magnesium and oxygen, the ratio of magnesium to oxygen in magnesium oxide is 1:1. Based on this 1:1 ratio, the empirical formula for magnesium oxide is MgO.
  2. MgO₂
  3. MgO₃
  4. Mg₃O
6) What is the concentration in ppm of 0.001 g of lead dissolved in 1 kg of water?
  1. 1 ppm
    The formula for calculating parts per million (ppm) is: ppm = (mass of solute/mass of solution) × 1,000,000 Inserting the values into the formula: ppm = (0.001 g/1,000 g) × 1,000,000 ppm = 0.000001 × 1,000,000 ppm = 1 ppm
  2. 10 ppm
  3. 100 ppm
  4. 1,000 ppm
7) Calculate the amount of solute dissolved in 4 dm³ of a 0.2 mol/dm³ solution.
  1. 0.05 mol
  2. 0.8 mol
    The concentration formula is: concentration = amount of solute/volume of solution The question asks us to find the amount of solute. Therefore, we need to rearrange the formula to solve for the amount of solute: solute amount = concentration × volume Inserting the values into the rearranged formula: solute amount = concentration × volume solute amount = 0.2 mol/dm³ × 4 dm³ solute amount = 0.8 mol
  3. 3.8 mol
  4. 4.2 mol
8) Assuming volumes are additive, how much solute is needed to prepare 950 mL of a solution made from 7 parts solute and 10 parts solvent?
  1. 58 mL
  2. 101 mL
  3. 391 mL
    A solute-to-solvent dilution ratio of 7:10 means the solution contains 7 parts solute and 10 parts solvent, making 17 parts in total. In other words, 7/17ths of the solution is solute. To find the volume of solute in a solution, multiply the volume of the final solution by the fraction of the solution that is solute: 950 mL × 7/17 = 391 mL of solute
  4. 559 mL
9) What is the purpose of a custody seal on a sample container?
  1. To help identify the sample if the container is misplaced
  2. To prevent air from entering the container
  3. To show whether the container has been tampered with
    Custody seals provide proof if a container has been opened or tampered with. They are commonly used in forensic testing to protect the integrity of the sample.
  4. To show who currently has custody of the container
10) A courier delivers a chain of custody sample to a technician at a laboratory. Who needs to sign and date the chain of custody form?
  1. Only the courier
  2. Only the laboratory technician
  3. The courier and the laboratory technician
    Every time a chain of custody sample changes hands, the person giving it and the person receiving it must sign and date the chain-of-custody form.
  4. The laboratory manager and the laboratory technician
11) What are class 8 hazardous materials?
  1. Corrosive
    Class 8 hazardous materials are corrosives. They destroy living tissue and corrode metals. They include acids and bases that can cause chemical burns on contact.
  2. Explosive
  3. Poisonous
  4. Radioactive
12) What are class 1 hazardous materials?
  1. Explosive
    Class 1 hazardous materials are explosives.
  2. Infectious
  3. Poisonous
  4. Radioactive
13) What type of hazard are OSHA action levels for?
  1. Chemicals and noise
    OSHA action levels are for hazardous chemicals and occupational noise. An action level is a level of exposure that requires employers to take action. Examples of chemicals with OSHA action levels include formaldehyde, lead, and respirable crystalline silica.
  2. Ergonomic hazards
  3. Psychosocial hazards
  4. Slips, trips, and falls
14) According to OSHA standard 40 CFR 136, wastewater samples for organic tests must be stored below what temperature?
  1. −5°C
  2. 2°C
  3. 6°C
    Samples for any kind of organic test must be kept below 6°C.
  4. 10°C
15) Which danger must employers inform workers about under OSHA’s Hazard Communication Standard?
  1. Bloodborne pathogens
  2. Dangerous chemicals
    OSHA’s Hazard Communication Standard requires employers to inform workers about the hazards of dangerous chemicals used in the workplace.
  3. General safety hazards
  4. Miscommunication
16) Most OSHA permissible exposure limits (PELs) are time-weighted averages of how many hours?
  1. 1
  2. 2
  3. 4
  4. 8
    Most OSHA PELs are 8-hour time-weighted averages.
17) OSHA considers a confined space as oxygen-deficient if its oxygen level is below:
  1. 19.5%
    According to OSHA, the minimum safe oxygen level in a confined space is 19.5%. If the oxygen level is below this, you'll need to wear respiratory protection.
  2. 20.1%
  3. 20.4%
  4. 20.9%
18) According to OSHA standard 1910.95, employers must implement a noise monitoring program when an employee's noise exposure equals or exceeds an 8-hour time-weighted average of how many decibels?
  1. 85 dB
  2. 90 dB
  3. 95 dB
  4. 100 dB
19) Which device is typically used to separate grit from organics in grit slurries?
  1. Aerated grit chamber
  2. Air lift
  3. Clarifier
  4. Hydrocyclone
    Hydrocyclones are typically used to separate grit from organics in grit slurries and to remove grit from primary sludge. These devices spin the grit out of the slurry using centrifugal force.
20) A wastewater treatment plant has 150,000 lbs of mixed liquor volatile suspended solids (MLVSS) in the aeration tank. The primary effluent has a BOD of 75,000 lbs per day. Calculate the F/M ratio.
  1. 0.5
    The formula for the F/M ratio is: F/M ratio = BOD per day in lbs/MLVSS in lbs Inserting the values into the formula: F/M ratio = 75,000 lb/150,000 lb F/M ratio = 0.5
  2. 1
  3. 1.5
  4. 2
21) Which of these water indicators is reported in μg/L?
  1. Temperature
  2. Total toxic organics
  3. Turbidity
  4. pH
22) Which dye is used to detect the presence of anionic surfactants in water samples?
  1. Methylene blue
    Anionic surfactants in a water sample can be detected with a methylene blue active substances (MBAS) assay. This is a colorimetric analysis test method that uses methylene blue.
  2. Nile red
  3. Oil red
  4. Thymolphthalein
23) An environmental inspector collects a sample of water for a BOD₅ test but cannot start the test until tomorrow morning. How should the sample be stored in the meantime?
  1. At room temperature
  2. In a freezer
  3. In a refrigerator
    Samples can degrade quickly. If you cannot start a BOD₅ test within two hours of collecting the sample, you should chill the sample (at a temperature of 1–4°C).
  4. In a vacuum flask
24) An aeration tank has a volume of 100 m³ and an influent flow rate of 10 m³/hour. Calculate the hydraulic retention time of the aeration tank.
  1. 0.1 hours
  2. 10 hours
    The formula for hydraulic retention time is: hydraulic retention time = volume/flow rate Inserting the values into the formula: hydraulic retention time = 100/10 hydraulic retention time = 10 hours
  3. 100 hours
  4. 1,000 hours
25) What are the three characteristics of a confined space?
  1. Has a restricted entry and exit, contains serious safety hazards, and is large enough to work in
  2. Has a restricted entry and exit, contains serious safety hazards, and is too small to work in
  3. Has a restricted entry and exit, is not meant for continuous occupancy, and is large enough to work in
  4. Has a restricted entry and exit, is not meant for continuous occupancy, and is too small to work in
26) An aeration basin has a dark brown, almost black sudsy foam that covers the entire basin. The foam smells sour. What is the most likely cause?
  1. Anaerobic conditions in the aeration basin
    Dark sudsy foam with a septic or sour odor is a sign of anaerobic conditions in the aeration basin. Check DO levels in the basin and increase aeration/mixing. Reduce organic loading if possible.
  2. Filamentous organisms are present
  3. The RAS flow is too low
  4. The aeration basin has excessive solids due to insufficient wasting
27) Which stage of wastewater treatment separates readily settleable and floatable solids from the wastewater?
  1. Primary
    The objective of primary treatment is to remove settleable solids by sedimentation and to remove materials that will float (scum) by skimming.
  2. Secondary
  3. Tertiary
  4. Quarternary
28) Which of these units is a typical unit used to measure flow?
  1. CFS
    CFS stands for cubic feet per second and is a typical unit used to measure flow. Other units used to measure flow are GPM (gallons per minute) and MGD (million gallons per day)
  2. MPH
  3. liters
  4. mg/L
29) Total Kjeldahl nitrogen (TKN) is the total concentration of:
  1. nitrate and ammonia
  2. nitrate and nitrite
  3. organic nitrogen and ammonia
  4. organic nitrogen and nitrite
30) Which section of the Code of Federal Regulations sets the standards for the use and disposal of sewage sludge?
  1. 20 CFR Part 136
  2. 20 CFR Part 1910.1450
  3. 40 CFR Part 403
  4. 40 CFR Part 503
31) Workers can warn traffic of their presence in the street with signs, cones, and:
  1. banners
  2. billboards
  3. chairs
  4. flagmen
32) What is the typical unit for reporting water alkalinity?
  1. mEq OH−
  2. mEq/kg
  3. mg/L CaCO₃
    In the US, water alkalinity is usually reported as mg/L CaCO₃ since most alkalinity is derived from the weathering of carbonate minerals. Alkalinity can also be reported in milliequivalents per liter (mEq/L).
  4. mol NaOH
33) An industry has three sewer connections with the following discharge rates: 1) 100 gpd 2) 300 gpd 3) 600 gpd. A flow-weighted composite sample of 2 liters is needed. How many milliliters of sample from each connection should be composited?
  1. 0.1 mL, 0.3 mL, 0.6 mL
  2. 100 mL, 300 mL, 600 mL
  3. 200 mL, 600 mL, 1,200 mL
    Step 1) Add up the discharge rates 100 + 300 + 600 = 1,000 gpd Step 2) Calculate the fraction for each connection
    1. 100/1000 = 0.1
    2. 300/1000 = 0.3
    3. 600/1000 = 0.6
    Step 3) Multiply each fraction by 2 liters
    1. 0.1 x 2,000 mL = 200 mL
    2. 0.3 x 2,000 mL = 600 mL
    3. 0.6 x 2,000 mL = 1,200 mL
  4. 500 mL, 750 mL, 750 mL
34) Which of these wastewater components takes the longest to biodegrade?
  1. Carbohydrates
  2. Fats
    Fats are classified as slowly biodegradable substances. Among the options, fats take the longest to biodegrade in wastewater. For this reason, the removal of fats often requires specific processes in wastewater treatment to enhance their breakdown.
  3. Glucose
  4. Proteins
35) Why is chlorine added during water treatment?
  1. To accelerate sedimentation
  2. To destroy microorganisms
    Chlorine is the most common type of drinking water disinfection. It kills bacteria, viruses, and other microorganisms in drinking water that would otherwise cause disease and illness.
  3. To enhance water taste and odor
  4. To reduce water hardness
36) A rectangular pond has a length of 500 feet, a width of 200 feet, and a depth of 10 feet. Calculate the surface area of the pond in acres.
  1. 1.7 acres
  2. 2.3 acres
    First, calculate the area of the pond in square feet. The formula to calculate area is: area = length × width Inserting the values into the formula: area = 500 × 200 area = 100,000 square feet To convert square feet to acres, divide the number of square feet by 43,560: 100,000/43,560 = 2.2957 acres Rounded to one decimal place, the pond's surface area is approximately 2.3 acres.
  3. 3.8 acres
  4. 4.5 acres
37) PSI is a unit of:
  1. distance
  2. energy
  3. pressure
    PSI stands for "pounds per square inch" and is a unit of pressure.
  4. time
38) What does the unit MGD refer to?
  1. Milligallons per day
  2. Milligrams per day
  3. Million gallons per day
    MGD is a measurement of water flow and means million gallons per day.
  4. Thousand gallons per day
39) VCP stands for ________ ________ pipe.
  1. vacuum channel
  2. verified capacity
  3. vinyl chloride
  4. vitrified clay
    Vitrified clay pipe (VCP) is pipe made from a blend of clay and shale that has been subjected to high temperature to achieve vitrification, which results in a hard, inert ceramic.
40) As per 40 CFR 403.5, what is the maximum holding time for wastewater samples intended for salmonella testing?
  1. 30 minutes
  2. 8 hours
  3. 28 hours
  4. 7 days
41) Grab samples are also known as __________ samples.
  1. composite
  2. discrete
  3. sequential
  4. time-proportional
42) What is the difference between nitrate and nitrite?
  1. Nitrate has three hydrogen atoms while nitrite has two
  2. Nitrate has three oxygen atoms while nitrite has two
    Nitrate is NO₃ (one nitrogen atom and three oxygen atoms) while nitrite is NO₂ (one nitrogen atom and two oxygen atoms).
  3. Nitrate has two hydrogen atoms while nitrite has three
  4. Nitrate has two oxygen atoms while nitrite has three
43) What is the term for the liquid between the sludge and scum in a digester?
  1. Filtrate
  2. Sewage
  3. Slush
  4. Supernatant
    The supernatant is the relatively clear water layer between the sludge on the bottom and the scum on the surface of an anaerobic digester.
44) The following copper results, in mg/L, were taken throughout the day: 4.7, 5.1, 5.4, 6.2, 6.1, 5.9, 4.2, 3.5, 3.5, 3.4. Calculate the mean of these results.
  1. 4.5
  2. 4.6
  3. 4.7
  4. 4.8
    Step 1) Sum the results 4.7 + 5.1 + 5.4 + 6.2 + 6.1 + 5.9 + 4.2 + 3.5 + 3.5 + 3.4 = 48 Step 2) Divide the sum by the number of results 48/10 = 4.8
45) What is graywater?
  1. Water from sinks, showers, bathtubs, and washing machines
  2. Water that contains soil
  3. Water that has been cleaned at a water treatment plant
  4. Water that has come into contact with feces
46) 40 CFR 136 of the Federal Code of Regulations contains:
  1. guidelines establishing test procedures for the analysis of pollutants
  2. hazardous waste injection restrictions
  3. state UIC program requirements
  4. toxic pollutant effluent standards
47) Denitrification is the ____________________ to nitrogen gas.
  1. oxidation of ammonia
  2. oxidation of nitrate
  3. reduction of ammonia
  4. reduction of nitrate
    Denitrification is the reduction (removal of oxygen) of nitrate to form nitrogen gas.
48) Which wastewater treatment process is typically accomplished by adding sulfur dioxide?
  1. Dechlorination
    Dechlorination is the process of removing residual chlorine from disinfected wastewater. Sulfur dioxide is the most common method of dechlorination.
  2. Digestion
  3. Disinfection
  4. Thickening
49) What do the terms "Schedule 40" and "Schedule 80" refer to?
  1. Employer workplace rights
  2. The storage of dangerous chemicals
  3. The thickness of pipes
  4. Wastewater legislation
50) Which of these types of waste is found in food industry effluents?
  1. BOD
  2. Cyanide
  3. Nitrates
  4. Polychlorinated biphenyl
51) What is the first step of wastewater treatment?
  1. Grit removal
    Grit removal – the process of settling out heavy particles like sand and gravel – is the step after screening.
  2. Screening
    Screening is the first stage of wastewater treatment. The aim of screening is to remove objects such as rags, paper, and plastics to prevent clogging of equipment further downstream.
  3. Sedimentation
  4. Trickling filters
52) What is 100 feet of head in PSI?
  1. 2.9 PSI
  2. 14.0 PSI
  3. 28.2 PSI
  4. 43.3 PSI
    Pressure is measured in either PSI (pounds per square inch) or feet of head. To convert from feet of head to PSI, multiply by 0.433: 100 feet of head × 0.433 = 43.3 PSI
53) Which of these is required on an inspection report for a wastewater treatment plant?
  1. Contact details of the maintenance contractor
  2. HHE-200 septic permit number
  3. Name of the inspector
  4. Signature of the plant manager
54) A clarifier has a volume of 200,000 gallons and a flow rate of 2.4 MGD. Calculate the detention time of the clarifier.
  1. 2 hours
    Step 1. Convert the flow rate to gallons per hour MGD means million gallons per day. A day has 24 hours, so to convert MGD into hours, divide by 24: 2,400,000/24 = 100,000 gallons per hour Step 2. Calculate the detention time The formula for detention time is: detention time = volume/flow rate Inserting the values into the formula: detention time = 200,000/100,000 detention time = 2 hours
  2. 2.5 hours
  3. 3.5 hours
  4. 3 hours
55) Calcium hydroxide is also known as:
  1. caustic soda
    Lye and caustic sodium are terms for sodium hydroxide.
  2. lye
  3. quick lime
    Quick lime, also called caustic lime, is another term for calcium oxide.
  4. slaked lime
    Slaked lime is the common name for calcium hydroxide.
56) Which agency is responsible for administering and enforcing the General Pretreatment Regulations?
  1. Department of Energy (DOE)
  2. Environmental Protection Agency (EPA)
  3. Food and Drug Administration (FDA)
  4. Occupational Safety and Health Administration (OSHA)
57) A wastewater sample of 100 mL is diluted to 300 mL with water. The initial DO of the sample is 50 mg/L. After 5 days, the DO has fallen to 10 mg/L. Calculate the BOD₅ of the sample in mg/L.
  1. 120 mg/L
    Step 1) Calculate the dilution factor The formula for dilution factor is: dilution factor = total volume/sample volume Inserting the values into the formula: dilution factor = 300/100 = 3 Step 2) Calculate the BOD₅ The formula for BOD₅ is: (initial DO − final DO) × dilution factor Inserting the values into the formula: BOD₅ = (50 − 10) × 3 BOD₅ = 40 × 3 BOD₅ = 120 mg/L
  2. 245 mg/L
  3. 500 mg/L
  4. 600 mg/L
58) Which of these is a conventional pollutant?
  1. Ammonia
  2. Chromium
  3. Cyanide
  4. Oil
    Conventional pollutants are any water pollutants that can be treated by a municipal sewage treatment plant. Examples of conventional pollutants are oil, grease, biochemical oxygen demand, total suspended solids, fecal coliform, and pH.
59) What are field blanks?
  1. Bottles of clean water
    Field blanks are simply samples of clean water. They are carried with the field samples. They can tell you if contamination was accidentally introduced during sample collection.
  2. Collection systems of unknown water quality
  3. Disposable, single-use sampling devices
  4. Water samples taken upstream from incoming pollutants
60) A developer anticipates that a new site will produce 500 gallons of wastewater per day. The sewer impact fee is $31.23 per gallon of wastewater per day. Calculate the total daily sewer impact fee.
  1. $10,835
  2. $15,615
    $31.23 × 500 = $15,615
  3. $20,935
  4. $25,815
61) Electromagnetic flowmeters measure flow by measuring the _________ created by the movement of water.
  1. area
  2. depth
  3. pressure differential
  4. voltage
62) Goggles, earplugs, and gloves are needed when using a:
  1. gas detector
  2. pH meter
  3. power grinder
  4. sampling pump
63) What is the most oxidized form of nitrogen found in wastewater?
  1. Ammonia
  2. Nitrate
    Nitrate is the most oxidized form of nitrogen found in wastewater. The molecule has three oxygen atoms. Nitrate only has two oxygen atoms and ammonia has none.
  3. Nitrite
  4. Organic nitrogen
    Organic nitrogen is the nitrogen atoms that occur in organic compounds.
64) A factory generates 0.12 MGD of wastewater. The treatment system can treat 200 GPM. How many hours would it take the treatment system to process one day’s wastewater?
  1. 2
  2. 6
  3. 10
    Step 1: Calculate the total daily wastewater The question asks how long the system needs to process a day's wastewater. 0.12 MGD means "0.12 million gallons per day" which means the factory produces 120,000 gallons of wastewater in one day. Therefore a day's wastewater is 120,000 gallons. Step 2: Understand the treatment system capacity GPM means "gallons per minute". 200 GPM means the treatment system can process 200 gallons every minute. Step 3: Calculate the time required in minutes If the system can process 200 gallons a minute, we can work out how many minutes it would take to process 120,000 gallons: 120,000 gallons/200 GPM = 600 minutes Convert minutes to hours To convert from minutes to hours, divide by 60: 600/60 = 10 hours
  4. 14
65) Which of these items of safety equipment is NOT required in an inspector's vehicle?
  1. Fire extinguisher
  2. First aid kit
  3. Spill control pillows
  4. Stop signs
    A fire extinguisher, first aid kit, and spill control pillows must be in each inspector's vehicle.
66) What organization enforces the pretreatment requirements of the Clean Water Act?
  1. EPA
    The EPA (Environmental Protection Agency) enforces the Clean Water Act and ensures that pretreatment facilities comply with it.
  2. NOAA
  3. The Department of Energy
  4. The Department of Health and Human Services
67) What is the main difference between primary clarifiers and secondary clarifiers?
  1. The density of the sludge handled
    Solids in primary clarifiers are typically inorganic and less dense. In contrast, solids in secondary clarifiers are nearly 100% organic and compact readily, making the sludge far denser.
  2. The flow rate through the clarifiers
  3. The number of clarifiers required
  4. The sludge removal systems
68) An industrial discharger has a wastewater flow of 50,000 liters per day containing 4.5 mg/L of copper. What is the mass emission rate of copper in grams per day?
  1. 12.5 g/day
  2. 225 g/day
    The formula for mass emission rate is: concentration × flow rate The question tells us:
    • concentration = 4.5 mg/L
    • flow rate = 50,000 L per day
    Inserting these values into the formula: mass emission rate = 50,000 × 4.5 mass emission rate = 225,000 mg per day Finally, to convert from milligrams to grams, divide by 1,000: 225,000 mg/1,000 = 225 g
  3. 5 g/day
  4. 90 g/day
69) What is the most common toxic gas encountered during sampling work?
  1. Carbon monoxide
  2. Hydrogen cyanide
  3. Hydrogen sulfide
  4. Methane
70) The following calcium results, in mg/L, were taken throughout the day: 200, 241, 231, 242, 192 What is the range of these results?
  1. 50
    The range is the difference between the highest result and the lowest result. In this case, the range is 242 − 192 = 50.
  2. 100
  3. 150
  4. 200
71) Which of these has the lowest BOD?
  1. Rainwater
    The cleaner the water, the lower the BOD. Untreated municipal water has the highest BOD while rainwater, being the cleanest, has the lowest BOD.
  2. Treated municipal water
  3. Unpolluted river water
  4. Untreated municipal water
72) A circular spill has a radius of 10 feet and an average depth of 2 feet. Estimate the volume of the spill in gallons.
  1. 2,100
  2. 3,800
  3. 4,700
    Step 1) Calculate the volume of the spill The spill can be imagined as a cylinder. The formula for calculating the volume of a cylinder is: volume = π × radius² × height Inserting the values into the formula: volume = π × 10² × 2 volume = π × 100 × 2 volume = π × 200 volume = 628.4 ft³ Step 2) Convert the volume to gallons To convert from cubic feet to gallons, multiply by 7.48: 628.4 cubic feet × 7.48 = 4,700 gallons Therefore, the estimated volume of the spill is approximately 4,700 gallons.
  4. 5,300
73) Composite samples are collected by combining two or more __________ samples.
  1. time-proportional
  2. discrete
    A composite sample is collected by combining discrete (a.k.a. grab) samples.
  3. aggregate
  4. flow-proportional
74) What is Manning's formula?
  1. V = (1.49/A) × n²ᐟ³ × S × √R
  2. V = (1.49/n) × A × R²ᐟ³ × √S
    Manning's formula describes the relationship between the flow velocity, cross-sectional area, hydraulic radius, and slope in open channel flows. Manning's formula states that the flow velocity (V) is equal to a constant (1.49) divided by the roughness coefficient (n), multiplied by the cross-sectional area of flow (A), multiplied by the hydraulic radius (R) raised to the power of 2/3, and multiplied by the square root of the slope of the channel (S).
  3. V = (A/1.49) × n × R²ᐟ³ × √S
  4. V = (n/1.49) × A²ᐟ³ × S × √R
75) What is the term for a chemical that lowers the surface tension of a liquid?
  1. Liquefactant
  2. Liquescent
  3. Surfactant
    Surfactants are molecules that lower the surface tension of liquids. Surfactants commonly have one end that is hydrophilic and the other that is hydrophobic.
  4. Tensile
76) Water hardness is a measure of the amount of which two minerals in water?
  1. Calcium and magnesium
    Water hardness measures the amount of calcium and magnesium present in water.
  2. Iron and phosphorous
  3. Nitrogen and oxygen
  4. Sodium and fluoride
77) What is the main purpose of the General Pretreatment Regulations?
  1. Ensure safe drinking water
  2. Prevent damage to POTWs
    The primary purpose of the General Pretreatment Regulations is to prevent the discharge of pollutants that could damage POTWs (publicly owned treatment works). This includes pollutants that are a fire or explosion hazard, pollutants that can corrode infrastructure, and pollutants that could obstruct the flow in the POTW.
  3. Promote wildlife conservation
  4. Regulate air quality
78) What is the term for a sample collected at a single location at a single point in time?
  1. Composite
  2. Flow-proportional
  3. Grab
    Grab samples are one-off samples. They are the most common type of sample.
  4. Time-proportional
79) What is the Venturi principle?
  1. Fluid pressure reduces when the fluid flows through a constricted section of a pipe
    The Venturi effect describes how the velocity of a fluid increases and the pressure decreases as the pipe becomes more constricted.
  2. Fluids have constant densities, regardless of pressure variations in the flow
  3. Fluids passing from higher to lower elevations maintain a steady velocity
  4. In a steady flow, the sum of all forms of energy in a fluid along a streamline is the same at all points on that streamline
80) Which of these industry types generally produces a very high suspended solids content?
  1. Breweries
    Wastewater from breweries is high in sugar and alcohol, causing very high levels of total suspended solids.
  2. Laundries
  3. Oil fields
  4. Textile dyehouses
81) How should an inspector be able to activate emergency response procedures?
  1. By calling the police and fire departments
  2. By contacting local TV and radio stations
  3. By making one call to a person in the home office
  4. By phoning the collection system and treatment plant superintendents
82) Which of these items should an inspector examine at high-risk industrial facilities with regard to emergency response?
  1. Chemical ordering plan
  2. Future expansion plan
  3. Spare parts inventory plan
  4. Spill prevention plan
83) The EPA recognizes what types of dischargers in its efforts to control the flow of pollutants into water?
  1. Direct and indirect
  2. Municipal and industrial
  3. Raw and treated
  4. Sanitary and storm
84) A sodium chloride solution contains 25% sodium chloride and has a density of 2 g/mL. How many grams of sodium chloride are in one liter of the solution?
  1. 0.5 grams
  2. 2 grams
  3. 500 grams
    Step 1) Convert g/mL to g/L The question gives the density in g/mL but asks you for the number of grams in one liter (g/L). Therefore the first step is to convert from g/mL to g/L. To convert g/mL to g/L, multiply by 1,000: 2 g/mL × 1,000 = 2,000 g/L Step 2) Calculate 25% of the total Multiply by 0.25 to find the amount of sodium chloride: 2,000 g/L × 0.25 = 500 g/L Therefore, one liter of the solution has 500 grams of sodium chloride.
  4. 2,000 grams
85) Which of these chemicals may cause explosions in sewers?
  1. Acetic acid
  2. Carbon tetrachloride
  3. Gasoline
  4. Hexavalent chromium
86) A flow rate of one cubic foot per second is equal to how many gallons per hour?
  1. 26,928
    Step 1) Convert ft³ to gallons First, convert the flow rate from cubic feet to gallons. To do this, multiply by 7.48: 1 cubic foot × 7.48 = 7.48 gallons Step 2) Convert seconds to hours The flow rate is 7.48 gallons per second. To convert this to hours, multiply by 3,600 (the number of seconds in an hour): 7.48 × 3,600 = 26,928 gallons per hour Therefore, a flow rate of one cubic foot per second is equal to 26,928 gallons per hour.
  2. 37,818
  3. 42,470
  4. 58,915
87) A POTW must retain Industrial user records for a minimum of how many years?
  1. 2
  2. 3
  3. 5
  4. 10
88) What is the average detention time for a 100,000 GPD flow going through a 3,000-gallon interceptor?
  1. 12 minutes
  2. 28 minutes
  3. 37 minutes
  4. 43 minutes
    Step 1: Calculate the detention time in days The formula for detention time is: detention time = volume/flow rate Inserting the values into the formula: detention time = 3,000/100,000 detention time = 0.03 days Step 2: Convert from days to minutes Convert from days to minutes by multiplying by 1,440 (the number of minutes in a day): 0.03 × 1,440 = 43.2 minutes Therefore, the average detention time is approximately 43 minutes.
89) The reason inspectors must keep notes during an emergency is because they will be useful in preparing:
  1. a briefing for public officials
  2. a case for court if enforcement action is initiated
  3. a meeting for reporters
  4. an informational pamphlet for the public
90) What is the best method to determine the pollutants that industrial dischargers are placing in collection systems?
  1. Field test kits
    Field test kits are not as accurate or detailed as laboratory tests.
  2. Laboratory chemical tests
    The best method to determine the pollutants that industrial dischargers are placing in collection systems is laboratory chemical tests. Laboratory chemical tests provide a more comprehensive and accurate analysis of pollutants than the other options.
  3. Results of industrial self-monitoring
  4. Visual observations
91) A batch tank has a water depth of 8 ft, a diameter of 6 ft, and a discharge rate of 10 GPM. How many hours will it take for the batch tank to empty?
  1. 2.8 hours
    Step 1) Calculate the volume of the tank A batch tank is a cylinder. The formula for calculating the volume of a cylinder is: volume = π × radius² × height Inserting the values into the formula: volume = π × 3² × 8 volume = π × 9 × 8 volume = π × 72 volume = 226.2 ft³ Step 2) Convert the volume to gallons To convert from cubic feet to gallons, multiply by 7.48: 226.2 cubic feet × 7.48 = 1691 gallons Therefore, the estimated volume of the batch tank is approximately 1691 gallons. Step 3) Calculate the number of minutes The question says the tank has a discharge rate of 10 GPM (gallons per minute). The formula for discharge rate is: discharge rate = volume/time We can rearrange this formula: time = volume/discharge rate Inserting the values into the formula: time = 1691/10 = 169.1 minutes Step 4) Convert minutes to hours To convert from minutes to hours, divide by 60: 169.1 minutes/60 = 2.8 hours Therefore, the batch tank will take approximately 2.8 hours to empty.
  2. 4.2 hours
  3. 7.4 hours
  4. 9.6 hours
92) A representative sample is:
  1. collected during minimum flows
  2. obtained when industrial representatives are present
  3. similar to the larger body of the waste stream being sampled
  4. transported to a laboratory for analysis
93) What is meant by chain of custody?
  1. A record of criminal action against an industrial discharger
  2. A record of each agency action leading to a notice of violation
  3. A record of every person who has access to a sample
  4. A record of every sample submitted to the laboratory
94) BOD is a measure of the amount of _______________ in water.
  1. biological organisms
  2. bound oxygen
  3. dissolved oxygen
  4. organic material
    Biochemical oxygen demand (BOD) indicates the amount of organic material in water. Specifically, BOD is the amount of dissolved oxygen needed by aerobic organisms to break down all the organic material in the water.
95) Which type of water stabilization pond has an aerobic zone at the top and an anaerobic zone at the bottom?
  1. Facultative
    Facultative ponds have an aerobic zone at the top and an anaerobic zone at the bottom. The aerobic conditions at the top are created by algae. The anaerobic conditions at the bottom are created by the high demand for oxygen in the settled solids.
  2. Aerobic
  3. Anaerobic
  4. Maturation
96) In the context of wastewater treatment, what does FOG mean?
  1. Fats, oils, and grease
  2. Filamentous organisms
  3. Free oxygen grade
  4. Fully organic grade
97) The focus of pollution prevention is to ______________ waste generated.
  1. dispose of
  2. minimize
    Pollution prevention means eliminating or reducing the amount and toxicity of potentially harmful substances at their sources, before generation, treatment, recycling or disposal.
  3. recycle
  4. treat
98) Which Federal Act introduced the concept that waste generators are responsible for their waste from cradle to grave?
  1. Comprehensive Environmental Response, Compensation and Liability Act
  2. Resource Conservation and Recovery Act
  3. Superfund Amendments and Reauthorization Act
  4. Toxic Substances Control Act
99) Industrial wastewater discharge permits grant permission to discharge wastewater into:
  1. a pretreatment facility
  2. the centralized waste treatment facility
  3. the environment
  4. the wastewater collection system
100) Which of these is a danger of hydrogen sulfide in sewers?
  1. Pipe corrosion
  2. Pathogen growth
  3. Carcinogenicity
  4. Toxic gas
101) The wastewater discharge of a factory is sampled every 300 gallons. What is the term for this type of sampling?
  1. Continuous
  2. Discrete
  3. Flow-proportional
    Flow-proportional samples are taken every x number of gallons discharged.
  4. Time-proportional
102) The figure below shows the horizontal cross-section of a water tank in the shape of a rectangle with a semi-circle at one end. If the water in the tank is 7 meters deep, then what is the volume of water in the tank in gallons?
  1. 110,547 gallons
    Step 1) Calculate the area of the rectangle The formula to calculate the area of a rectangle is: area = length × width Inserting the values into the formula: 10 m × 5 m = 50 m² Step 2) Calculate the area of the semi-circle The formula to calculate the area of a circle is: area = π × radius² The diameter is 5 meters, so the radius is 2.5 meters. Inserting the values into the formula: area = π × 2.5² area = π × 6.25 area = 19.6 m² Since we are dealing with a semi-circle, we divide by 2: 19.6/2 = 9.8 m² Step 3) Calculate the total area 50 m² + 9.82 m² = 59.82 m² Step 4) Calculate the volume of water in m³ Multiply the water area by the water depth to find the water volume: 59.82 m² × 7 m = 418.74 m³ Step 5) Convert m³ to liters To convert m³ to liters, multiply by 1,000: 418.74 m³ × 1,000 = 418,740 liters Step 6) Convert the liters to gallons To convert liters to gallons, multiply by 0.264: 418,740 × 0.264 = 110,547 gallons
  2. 222,938 gallons
  3. 319,937 gallons
  4. 483,885 gallons
103) Lead acetate paper is used to determine the presence of which dangerous gas?
  1. Carbon monoxide
  2. Hydrogen sulfide
    Hydrogen sulfide turns lead acetate paper brown or black.
  3. Methane
  4. Nitrogen dioxide
104) The main pollutants from the production of printed circuit boards are organic matter, ammonia, and:
  1. copper
  2. mercury
  3. silicon
  4. steel
105) For how long is the BOD₅ test run?
  1. 5 minutes
  2. 5 hours
  3. 5 days
    The BOD₅ test measures the biological oxygen demand of a water sample over five days.
  4. 5 weeks
106) A pretreatment system has a capacity of 100 gallons per minute. In how many hours can the facility process 60,000 gallons?
  1. 10 hours
    The formula for flow rate is: flow rate = volume/time We can rearrange this formula to solve for time: time = volume/flow rate Inserting the values into the formula: time = 60,000/100 = 600 minutes To convert from minutes to hours, divide by 60: 600/60 = 10 hours Therefore, the facility can process 60,000 gallons in 10 hours.
  2. 12 hours
  3. 14 hours
  4. 16 hours
107) Maturation ponds are:
  1. aerobic on the top and anaerobic on the bottom
  2. anaerobic on the top and aerobic on the bottom
  3. wholly aerobic
    Maturation ponds have aerobic conditions throughout, from the surface to the bottom.
  4. wholly anaerobic
108) In the context of water treatment and purification, MLSS is the:
  1. amount of solids removed from an activated sludge reactor
  2. concentration of suspended solids in mixed liquor of an aeration tank
    MLSS stands for Mixed Liquor Suspended Solids and is the concentration of suspended solids in mixed liquor of an aeration tank.
  3. mixture of wastewater and microorganisms returned to the head of an aeration tank
  4. underflow from a secondary sedimentation tank
109) In the context of wastewater treatment, what does SSO stand for?
  1. Sanitary sewer overflow
    SSO stands for sanitary sewer overflow. SSO occurs when a sanitary sewer overflows and discharges untreated sewage into the environment.
  2. Single source outlet
  3. Surface-to-surface outfall
  4. Suspended solids and organics
110) In the context of wastewater treatment, what does F/M ratio mean?
  1. Fat-to-mineral ratio
  2. Flotsam-to-mixture ratio
  3. Flow-to-mass ratio
  4. Food-to-microorganism ratio
    The F/M ratio is the ratio of food (measured as BOD, COD, or TOC) to microorganisms.
111) Who is responsible for holding and maintaining an SPCC (Spill Prevention, Control, and Countermeasure) Plan for a facility?
  1. The Environmental Protection Agency
  2. The facility's safety officer
  3. The local government
  4. The owner or operator of the facility
    For facilities where an SPCC is necessary, it is the responsibility of the owner or operator of the facility to prepare and implement an SPCC Plan.
112) Calculate the total storage capacity, in gallons, of the following three tanks. Tank I: Cuboid tank measuring 5 feet on all sides. Tank II: Rectangular tank measuring 30 × 10 × 3 feet. Tank III: Cylindrical tank measuring 18 feet in diameter and 10 feet in height.
  1. 21,308 gallons
  2. 22,839 gallons
  3. 24,810 gallons
  4. 26,703 gallons
    Step 1) Find the volume of tank 1 The first tank is a cuboid, so we use the formula: volume = length × width × height volume = 5 ft × 5 ft × 5 ft volume = 125 ft³ Step 2) Find the volume of tank 2 The second tank is rectangular, so we use the same formula: volume = length × width × height volume = 30 ft × 10 ft × 3 ft volume = 900 ft³ Step 3) Find the volume of tank 3 The third tank is a cylinder, so we use the formula: volume = π × radius² × height The diameter is 18 feet so the radius is: radius = 18/2 = 9 feet Inserting the values into the formula: volume = π × 9² × 10 volume = π × 81 × 10 volume = π × 810 volume = 2,545 ft³ Step 4) Sum the volumes of the tanks Sum the volumes of the three tanks. 125 ft³ + 900 ft³ + 2,545 ft³ = 3,570 ft³ Step 5) Convert to gallons Convert ft³ to gallons by multiplying by 7.48: 3,570 ft³ × 7.48 = 26,703 gallons
113) An inspector needs to enter an area where a hazardous chemical is in use. How can the inspector find out which protective gear they need to wear?
  1. Ask a supervisor
  2. Ask an employee who works there
  3. Check the PPE policy
  4. Check the SDS
    Consulting the safety data sheet is the best place to begin when deciding on what type of protective gear to use.
114) An environmental compliance inspector records the following pH values at five locations of a wastewater influent: 9.1, 9.5, 8.9, 9.5, 10.0 What is the average of these five results?
  1. 9.4
    The formula for calculating the average is: average = sum/count First, sum up the results: 9.1 + 9.5 + 8.9 + 9.5 + 10.0 = 47 Then, divide the sum by the number of results: 47/5 = 9.4
  2. 9.5
  3. 9.6
  4. 9.7
115) What is the main danger of polychlorinated biphenyls (PCBs)?
  1. Carcinogenicity
    Polychlorinated biphenyls are highly carcinogenic. For this reason, their production has been banned in the United States.
  2. Combustibility
  3. Flammability
  4. Toxicity
116) What is the psi of a column of water with a height of 110.8 inches?
  1. 1
  2. 2
  3. 3
  4. 4
    To convert inches of water column to psi, divide by 27.7: 110.8/27.7 = 4 psi
117) What is the purpose of unannounced industrial inspections?
  1. To check the effluent quality
  2. To meet with a POTW's normal contact person
  3. To review paperwork
  4. To test the response of the industry
118) Which of these chemicals can be used to neutralize acidic wastewater?
  1. CH₃COOH
  2. Ca(OH)₂
    Ca(OH)₂ (calcium hydroxide, also known as lime) is a strong alkaline and can be used to neutralize acidic wastewater. CH₃COOH (acetic acid), HCl (hydrochloric acid), and HNO₃ (nitric acid) are all acids and would not neutralize acidic wastewater.
  3. HCl
  4. HNO₃
119) The effluent from Significant Industrial Users should be sampled at least every _____ months.
  1. 2
  2. 4
  3. 6
  4. 12
    The effluent from Significant Industrial Users should be sampled at least once a year.
120) If three pounds of sodium bisulfite are needed to reduce one pound of hexavalent chromium, then how many pounds of sodium bisulfite are needed to reduce 10,000 kg of hexavalent chromium?
  1. 10,001
  2. 28,376
  3. 48,103
  4. 66,138
    Step 1) Convert from kg to lb To convert from kilograms to pounds, multiply the kilograms by 2.2: 10,000 × 2.2 = 22,046 pounds Step 2) Calculate the pounds of sodium bisulfite needed The question says 3 pounds of sodium bisulfite are needed for every 1 pound of hexavalent chromium. So to find the number of pounds of sodium bisulfite needed, we multiply the number of pounds of hexavalent chromium by 3. 22,046 × 3 = 66,138 pounds
121) Which preservative is needed when collecting a sample for TKN (Total Kjeldahl Nitrogen) analysis?
  1. HCl to pH < 9
  2. HNO₃ to pH > 9
  3. H₂SO₄ to pH < 2
    H₂SO₄ (sulfuric acid) is the correct preservative for TKN samples.
  4. Zinc acetate + NaOH to pH < 2
122) Which preservative is needed when collecting a sample for total phosphorus analysis?
  1. HCl
    While HCl (hydrochloric acid) is a strong acid, it is not used to preserve samples for total phosphorus tests. Instead, HCl is used as a preservative for the analysis of total organic carbon, total dissolved carbon, iron, methane, oil and grease, and volatile organic compounds.
  2. H₂SO₄
    Samples for total phosphorus analysis must be kept at a pH below 2. Strong acids such as H₂SO₄ (sulfuric acid) and HNO₃ (nitric acid) are appropriate preservatives.
  3. KOH
    KOH (potassium hydroxide) is alkaline and therefore unsuitable.
  4. NaOH
    NaOH (sodium hydroxide) is alkaline and therefore unsuitable.
123) Which ion does pH measure?
  1. Carbon
  2. Hydrogen
    pH is the measurement of the hydrogen ion concentration in a liquid.
  3. Nitrogen
  4. Oxygen
124) A pH of 6.6 is:
  1. very acidic
  2. slightly acidic
  3. neutral
  4. slightly alkaline
125) Which pH is neutral?
  1. 0
  2. 1
  3. 3
  4. 7
    The pH scale ranges from 0 to 14, where 0 is extremely acidic, 14 is extremely basic (or alkaline), and 7 is neutral (meaning neither acidic nor basic).
126) Parts per million (ppm) can also be expressed as:
  1. cm³
  2. dm³
  3. mL/billion
  4. mg/L
    ppm stands for parts per million, which is a way of expressing very dilute concentrations of substances. 1 ppm means 1 part of a substance in 1,000,000 parts of the solution. In water solutions, 1 ppm is equivalent to 1 milligram of solute per liter of solution (mg/L), because 1 L of water ≈ 1 kg of water.
127) A pH of 2 is how many times more acidic than a pH of 5?
  1. 3
  2. 6
  3. 256
  4. 1,000
    For each one-digit decrease in pH, the acidity increases by 10 times. This means:
    • A pH of 2 is 10 times more acidic than a pH of 3
    • A pH of 2 is 100 times more acidic than a pH of 4
    • A pH of 2 is 1,000 times more acidic than a pH of 5
128) 200 microliters is how many milliliters?
  1. 0.2 mL
    To convert from microliters to milliliters, divide the value by 1,000: 200 µL/1,000 = 0.2 mL
  2. 2 mL
  3. 20 mL
  4. 2,000 mL
129) What is 10 mg in micrograms?
  1. 0.0001 mcg
  2. 0.001 mcg
  3. 10,000 mcg
    To convert from milligrams to micrograms, multiply by 1,000: 10 mg × 1,000 = 10,000 mcg
  4. 100 mcg
130) In the equation KOH + CO₂ → K₂CO₃ + H₂O, which molecule needs a coefficient for the equation to be balanced?
  1. KOH
    KOH needs a coefficient of 2 for the equation to be balanced: 2KOH + CO₂ → K₂CO₃ + H₂O This balances the number of atoms for each element on both sides of the equation. Now each side has 2 potassium (K) atoms, 4 oxygen (O) atoms, 2 hydrogen (H) atoms, and 1 carbon (C) atom.
  2. CO₂
  3. K₂CO₃
  4. H₂O
131) Balance the equation Ag + H₂S → Ag₂S + H₂.
  1. 2Ag + H₂S → Ag₂S + H₂
    In the unbalanced equation, the left-hand side has one Ag atom, but the right-hand side has two Ag atoms. Therefore, the left-hand side needs one more Ag atom to balance the equation.
  2. 4Ag + 2H₂S → 2Ag₂S + H₂
  3. 2Ag + 2H₂S → Ag₂S + 4H₂
  4. 4Ag + H₂S → 2Ag₂S + H₂
132) How many gallons of a 0.1 M KOH solution will neutralize 30,000 gallons of 0.5 M HCl?
  1. 15,000
  2. 75,000
  3. 150,000
    The titration formula is M₁ × V₁ = M₂ × V₂ where:
    • M₁ is the molarity of solution 1
    • V₁ is the volume of solution 1
    • M₂ is the molarity of solution 2
    • V₂ is the volume of solution 2
    First, write the balanced equation: HCl + KOH = KCl + H₂O This equation shows that HCl and KOH react in a 1:1 molar ratio. Therefore, we do not need to adjust the stoichiometry in the calculation. Using the titration formula: M₁ × V₁ = M₂ × V₂ 0.5 × 30,000 gallons = 0.1 × V₂ 15,000 = 0.1 × V₂ 15,000/0.1 = V₂ 150,000 gallons = V₂
  4. 450,000
133) If 25 mL of LiOH is needed to neutralize 20 mL of 0.500 M HBr, what is the concentration of the LiOH?
  1. 0.4 M
    First, write the balanced chemical equation for the reaction: HBr + LiOH = LiBr + H₂O The equation shows that 1 mole of HBr reacts with 1 mole of LiOH. Therefore, we do not need to adjust the stoichiometry in the calculation. Using the titration formula: M₁ × V₁ = M₂ × V₂ 0.5 × 20 = M₂ × 25 10 = M₂ × 25 10/25 = M₂ 0.4 = M₂
  2. 0.5 M
  3. 0.6 M
  4. 0.75 M
134) 1 L of a 0.1 M potassium hydroxide solution neutralizes 50 mL of a sulfuric acid solution. What is the molarity of the sulfuric acid solution?
  1. 0.005 M
  2. 0.045 M
  3. 0.5 M
  4. 1 M
    Step 1) Write the balanced equation. H₂SO₄ + 2KOH = K₂SO₄ + 2H₂O This equation shows that H₂SO₄ (sulfuric acid) and KOH (potassium hydroxide) react in a 1:2 molar ratio. Step 2) Calculate the moles of KOH used in the titration: moles = molarity × volume moles = 0.1 M × 1 L moles = 0.1 moles Step 3) Calculate the moles of H₂SO₄. Since 1 mole of H₂SO₄ reacts with 2 moles of KOH, we need to divide the number of moles of KOH by 2 to find the number of moles of H₂SO₄: 0.1 moles/2 = 0.05 moles Step 4) Calculate the molarity of the H₂SO₄ solution: molarity = moles/volume molarity = 0.05/0.05 molarity = 1 M Therefore, the molarity of the H₂SO₄ solution is 1 M.
135) What is the lower flammability limit of carbon monoxide?
  1. 2%
  2. 4%
  3. 7%
  4. 12%
    Carbon monoxide has a lower flammability limit of 12%. This means concentrations of carbon monoxide below 12% cannot catch fire.
136) What is the lower flammability limit of methane?
  1. 1%
  2. 5%
    Methane has a lower flammability level of around 5%. If the atmosphere has less than 5% methane, an explosion cannot occur even if a source of ignition is present.
  3. 10%
  4. 17%
137) Under OSHA and GHS, which category of liquids has flashpoints between 23°C and 60°C?
  1. Category 1
  2. Category 2
  3. Category 3
    Category 1 and 2 liquids have flashpoints below 23 °C. Category 3 liquids have flashpoints of 23–60 °C. Category 4 liquids have flashpoints of 60–93 °C.
  4. Category 4
138) What is an upper flammability limit?
  1. The amount of fuel that will burn before the fuel burns itself out
  2. The highest concentration of a vapor that can catch fire
    The upper flammability limit is the highest concentration of a vapor in air that can burn. Above this limit, there is not enough oxygen for the vapor to burn.
  3. The highest temperature at which a liquid can be stored safely
  4. The highest temperature that a chemical can reach when ignited
139) Under OSHA regulations, a flammable liquid has a flash point at or below which temperature?
  1. 37.8°C
  2. 67.3°C
  3. 93°C
    The Occupational Safety and Health Administration (OSHA) defines a flammable liquid as any liquid with a flash point at or below 93°C.
  4. 100°C
140) In the context of occupational health and safety, what does STEL stand for?
  1. Short-term exposure limit
    The short-term exposure limit (STEL) is the amount of a substance that people can be exposed to over 15 minutes without harmful health effects.
  2. Standard task exposure limit
  3. Standard task equipment list
  4. Short-term emergency lighting
141) Safety goggles fall under which of the four levels of PPE?
  1. Level A
  2. Level B
  3. Level C
  4. Level D
    Safety goggles are level D PPE, the lowest level of personal protection equipment. Higher levels of PPE (A, B, and C) require the user to wear face masks or totally encapsulating suits instead.
142) What is the term for a substance with the potential to produce cancer in humans or animals?
  1. Carcinogen
    A carcinogen is any substance that can cause cancer in humans or animals. The word comes from carcino meaning "cancer" and gen meaning "causing".
  2. Caustic substance
  3. Nosocomial substance
  4. Pathogenic substance
143) What is the chemical formula for methane?
  1. CH₄
  2. C₂H₈
  3. C₈H₂
  4. C₈H₈
144) Complete the following reaction: HCl + Mg(OH)₂ → MgCl₂ + _______
  1. CO₂
  2. H₂O
    This is a neutralization reaction between an acid (HCl) and a base (Mg(OH)₂). The products of neutralization reactions are always salt (MgCl₂ in this case) and water (H₂O).
  3. O₂
  4. O₃
145) What is the chemical formula for hydrogen sulfide?
  1. HS
  2. HS₂
  3. H₂S
  4. H₂S₂
146) Calculate the density of a liquid that has a volume of 40 mL, a weight of 50 grams, and a boiling point of 110°C.
  1. 0.8 g/mL
  2. 0.9 g/mL
  3. 1.25 g/mL
    The formula for calculating density is: density = mass/volume Inserting the values into the formula: density = 50 g/40 mL density = 1.25 g/mL
  4. 1.5 g/mL
147) What is the TLV-C?
  1. The concentration a worker can be exposed to for one hour without adverse effect
  2. The concentration a worker can be exposed to over a working lifetime without adverse effects
  3. The concentration a worker can be exposed to up to 4 times per day
  4. The concentration that should never be exceeded
    TLV-C stands for Threshold Limit Value Ceiling. It is the exposure limit that should not be exceeded at any time.
148) During an eight-hour shift, an employee is exposed to zinc oxide fumes at a concentration of 150 ppm for two hours, 75 ppm for another two hours, and 50 ppm for four hours. Calculate the 8-hour time-weighted average.
  1. 81.25 ppm
    The formula for calculating the average is: average = sum/count In this case:
    • sum is the sum of the ppm for each hour
    • count is the total number of hours (8)
    First, sum the ppm-hours: 2 hours × 150 ppm = 300 ppm-hours 2 hours × 75 ppm = 150 ppm-hours 4 hours × 50 ppm = 200 ppm-hours 300 + 150 + 200 = 650 ppm Then, divide the sum by the total number of hours: 650 ppm-hours/8 hours = 81.25 ppm
  2. 88.515 ppm
  3. 91.75 ppm
  4. 95 ppm
149) What is the duration of the STEL?
  1. 5 minutes
  2. 15 minutes
    The STEL (short-term exposure limit) is the concentration of a substance a worker can be exposed to over a short period (usually 15 minutes) without injury.
  3. 1 hour
  4. 8 hours
150) Which pH buffer solution is typically used first when calibrating a pH meter?
  1. pH 1
  2. pH 4
  3. pH 7
    When calibrating a pH meter, a neutral buffer of pH 7 is typically used first. This is followed by a buffer of pH 4 or pH 10.
  4. pH 10

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About the CWEA ECI Grade 1 exam

What is the CWEA ECI Grade 1 exam?

The CWEA Environmental Compliance Inspector (ECI) exams are designed for people currently working as, or aspiring to become, Environmental Compliance Inspectors in California.

The exams are administered by the California Water Environment Association (CWEA), a professional organization dedicated to wastewater professionals in California.

The CWEA ECI exams are categorized into four grades: Grade 1, Grade 2, Grade 3, and Grade 4:

  • Grade 1 is the entry-level exam, ideal for beginners
  • Grade 2 is more challenging and suited for supervisory roles
  • Grade 3 is even more advanced, targeting middle-management positions
  • Grade 4 is the most difficult and is intended for upper-management roles.

While CWEA certification isn't mandatory for a job as an Environmental Compliance Inspector, it can help you get a job and can also lead to a pay raise and other benefits.

Applying to take the exam

To apply for the exam, download an application form at cwea.org/certification/apply, fill it in, and email it to memberservices@cwea.org.

The exam costs $209 for CWEA members and $448 for non-members. You can pay this fee by entering your credit card details on the application form.

If the CWEA approves your application, they will send you an approval email. Once you have this email, you can schedule your exam appointment through Pearson VUE's website.

You can take the exam at a test center in the US or at home on your computer. The exam is offered four times a year: in spring, summer, fall, and winter.

There are no education or work experience requirements to take the exam.

Exam day

If you take your exam at a test center, arrive at least fifteen minutes early. Bring at least one photo ID. Your photo ID must be current, valid, and government-issued (e.g., state driver’s license or passport).

If you take the exam at home, you will need to check in to the testing system online 15—30 minutes beforehand. During the check-in, an online proctor will ask you to take photos of your testing space to ensure your room is private and secure. You will not be allowed books, paper, calculators, sticky notes, whiteboards, or chalkboards, and the proctor may ask you to remove such material before the exam. The proctor will monitor you throughout the exam.

Whichever method of taking the exam you choose, an onscreen calculator will be available. If you take the exam at a test center, you may also bring your own calculator as long as it is from the CWEA-approved calculator list.

After you finish the exam, your result will immediately appear on the computer screen.

Passing the exam

The CWEA ECI Grade 1 exam has 100 questions. To pass the exam, you will generally need a score of at least 75% (although this may vary depending on the exam's difficulty).

Keeping your certification

After you pass the exam, you will need to meet the following requirements to keep your certification:

  • Submit 12 hours of continuing education every two years
  • Pay the annual renewal fee

What if I fail the exam?

If you fail the exam, you can retake it after paying the exam fee again.

Cancelling the exam

To reschedule or cancel an exam, contact Pearson VUE at least 24 hours before the exam is set to start.

Topics on the exam

The CWEA ECI Grade 1 exam covers 19 KSAs (Knowledge, Skills, and Abilities). These are outlined below.

KSA 101: Sampling

This KSA is about sampling and is worth 7% of the exam. You will need to know about:

  • sampling equipment and preservatives, including field blanks
  • sampling procedures, including grab samples
  • the terms turbidity and specific conductance
  • the correlation between BOD and COD
  • how to identify acids and bases
  • mathematics, including:
    • balancing chemical equations
    • dilution calculations
    • neutralization calculations
    • calculating the pH of an aqueous solution

KSA 102: Documentation

This KSA is about documentation relating to environmental compliance and is worth 5% of the exam. You will need to know about:

  • inspection reports
  • chain of custody procedures (why they are important, the containers and preservatives required for chain of custody procedures, etc.)

KSA 103: Field and laboratory tests

This KSA is worth 4% of the exam and will test your knowledge of:

  • field equipment (uses, preparation, and limitations)
  • gases and chemicals identified by field tests
  • identification of Total Toxic Organics

KSA 104: Inspection of pretreatment facilities

This KSA will test your knowledge of pretreatment facility inspection and is worth 9% of the exam. You will be tested on:

  • common wastewater pollutants
  • how to respond to facility violations
  • reverse osmosis and its use in industrial processes
  • rinse concurrent tanks and counter-current tanks
  • photo, x-ray, and silver removal processes
  • regulations related to wastewater discharges
    • the Federal Water Pollution Control Act of 1972
    • the Clean Water Act of 1977

KSA 105: Inspection of businesses

This KSA is like the previous KSA except it tests your knowledge of business inspection. The KSA is worth 9% of the exam and will ask you questions about:

  • stormwater
  • the pollution prevention hierarchy
  • non-compatible pollutants
  • spill response procedures
  • laws
    • regulations related to pollution prevention
    • regulations related to stormwater requirements

KSA 106: Pretreatment devices

This KSA is worth 6% and will test your knowledge of pretreatment devices, such as grease traps, interceptors, clarifiers, and silver recovery units. You may also be asked about:

  • ORP meters
  • gases generated in grease interceptors
  • the calculation of interceptor detention time

KSA 107: Maintainance of sampling equipment

This KSA is worth 4% and will ask you about:

  • the maintenance and calibration of sampling equipment and gas detectors
  • preservation methods according to 40 CFR 136

KSA 108: Use of sampling equipment

This KSA is worth 5% of the exam and will ask you about:

  • how to select the right sampling pump for a given situation
  • types of sampling (composite, grab, flow-proportional, discrete, etc.)
  • methods of calibrating pH meters

KSA 109: Call-outs

This KSA is worth 3% of the exam and will ask you questions about:

  • call-outs
  • the investigation of illegal waste discharges
  • emergency response procedures
  • spill procedures

KSA 110: Interaction with customers and staff

This KSA is worth 4% and will test your ability to communicate effectively and appropriately with staff and customers.

KSA 111: Safety

This KSA is worth 8% of the exam and will test your knowledge of safety practices, including:

  • personal protective equipment (PPE)
  • maximum safe sound levels
  • exposure limits of pollutants in the workplace
  • confined spaces
  • common gases encountered in sewer systems

KSA 112: Recording data from inspections

This KSA is worth 6% and will ask you questions about the recording of data for inspections. You will need to know about:

  • the conversion of liquid measurements
  • the calculation of flow rate, gallons discharged per day, etc.
  • Information required in an inspector's notebook

KSA 113: Keeping equipment and worksites safe

This KSA is worth 6% and will test your knowledge about the maintenance of equipment, materials, and worksites in an orderly and safe fashion. You will need to know about:

  • procedures to take when observing unsafe working conditions
  • types of confined spaces
  • concentrations of flammable gases that will cause combustion
  • pathogens
  • measuring gas levels with a gas detector

KSA 114: Staying current on developments in environmental compliance

This KSA is worth 3% and will ask you about the best sources to stay current on pretreatment regulations and the sources of information that workers in an Industrial User site should have access to.

KSA 115: Helping users maintain compliance with legal requirements

This KSA is worth 5% of the exam and will test you on maintaining program compliance with legal requirements through the issuing of permits and by guiding noncompliant users back to compliance.

KSA 116: Measurement of field conditions

This KSA is worth 4% and you will need to know how to measure various field conditions, including:

  • effluent
  • flow
  • pH
  • ORP
  • atmospheric gas
  • levels of combustibles

You will also need to know how to convert between different units of volume (gallons, liters, and cubic feet).

KSA 117: Sewer impact fees

This KSA is worth 2% and will ask you to measure and calculate sewer impact fees.

KSA 118: Reports

This KSA is worth 5% and will test your knowledge of preparing reports. You will need to know:

  • how to calculate water usage
  • terms relating to hazardous materials
  • how to review safety data sheets

KSA 119: Sanitary sewer overflows

This final KSA is worth 5% and will ask you about:

  • the different categories of sanitary sewer overflows
  • sampling procedures of sanitary sewer overflows