Download Illinois Private Sewage Contractor Ultimate Exam and more Exams Technology in PDF only on Docsity!
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Question 1. Which term describes wastewater that originates from household activities such as laundry, dishwashing, and toilet flushing? A) Industrial effluent B) Domestic sewage C) Stormwater runoff D) Agricultural runoff Answer: B Explanation: Domestic sewage is the wastewater generated from residential activities, including toilets, sinks, showers, and appliances. Question 2. In Illinois Private Sewage regulations, the “limiting layer” refers to: A) The topsoil layer that must be removed before trenching B) A soil horizon that restricts percolation rates below a specified minimum C) The layer of aggregate used beneath distribution pipes D) The concrete slab over a septic tank Answer: B Explanation: A limiting layer is a soil or rock stratum that slows infiltration, often requiring alternative designs or variances. Question 3. The “effective size” of a soil particle is defined as:
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A) The diameter of the largest particle present in a sample B) The size at which 10% of the soil mass is finer by weight C) The average particle size measured by sieve analysis D) The size of the particle that controls hydraulic conductivity Answer: B Explanation: Effective size (D₁₀) is the particle diameter at which 10% of the soil sample is finer, used in permeability calculations. Question 4. “Population Equivalent (PE)” is used to: A) Estimate the number of people a septic system can serve based on BOD load B) Determine the depth of a septic tank C) Calculate the required number of distribution boxes D) Set the minimum setback distance from a well Answer: A Explanation: PE converts wastewater flow into an equivalent number of persons, based on a standard BOD₅ load of 60 g/day. Question 5. Under the Private Sewage Disposal Licensing Act, a contractor must provide a bond of at least: A) $5, B) $10, C) $25,
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Explanation: Variance requests require comprehensive documentation to demonstrate why standard code cannot be met. Question 8. The proper procedure for a percolation test includes which of the following steps? A) Digging a 12-inch diameter hole, filling it with water, and timing the first 30 seconds only B) Preparing a 6-inch diameter hole, presoaking for 24 hours, then recording the drop over a 30-minute period C) Using a 4-inch diameter hole, no soaking, and measuring the time for water to disappear completely D) Conducting the test only after the trench is backfilled Answer: B Explanation: Illinois percolation testing requires a 6-inch hole, a 24 - hour presoak, and measurement of water level drop at specified intervals. Question 9. Minimum soil borings required for a new septic system in Illinois are: A) One boring per acre B) Two borings spaced 30 ft apart C) Three borings, each at least 50 ft apart within the system area D) Five borings, regardless of area size Answer: C
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Explanation: The code mandates at least three borings, each spaced a minimum of 50 ft apart, to adequately characterize the site. Question 10. Which of the following is considered a limiting layer for septic system design? A) Sandy loam with a percolation rate of 5 min/ft B) A 10-ft deep clay lens with a percolation rate of 150 min/ft C) A 2-ft thick gravel layer D) A well-drained silt loam Answer: B Explanation: A clay lens with a very slow percolation rate (e.g., 150 min/ft) restricts infiltration and is a limiting layer. Question 11. The minimum horizontal setback distance between a septic drain field and a private well in Illinois is: A) 10 ft B) 25 ft C) 50 ft D) 100 ft Answer: C Explanation: Illinois regulations require at least a 50-ft horizontal separation to protect drinking-water sources.
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Explanation: For systems above 500 gpd, the tank size must be 1.5 times the daily flow, yielding 1,800 gallons. Question 14. In a multi-compartment septic tank, the second compartment must be at least what percentage of the first compartment’s volume? A) 10 % B) 25 % C) 40 % D) 50 % Answer: B Explanation: Illinois code requires the second compartment to be at least 25 % of the first compartment’s volume to provide adequate settling. Question 15. Which material is NOT approved for constructing a septic tank in Illinois? A) Reinforced concrete B) Fiberglass C) Untreated wood logs D) High-density polyethylene (HDPE) Answer: C Explanation: Untreated wood is not permissible due to durability concerns; concrete, fiberglass, and HDPE are approved.
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Question 16. The minimum wall thickness for a concrete septic tank in Illinois is: A) 2 inches B) 4 inches C) 6 inches D) 8 inches Answer: B Explanation: The code specifies a minimum of 4-inch wall thickness for poured-in-place concrete tanks. Question 17. The required minimum drop between the inlet baffle and the tank outlet in a septic tank is: A) 0.5 inches B) 1 inch C) 2 inches D) 4 inches Answer: C Explanation: A minimum 2-inch drop ensures proper flow and prevents short-circuiting of the tank. Question 18. An abandoned septic tank must be: A) Covered with a concrete slab only
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Answer: B Explanation: Illinois code limits a single trench to 200 ft to ensure uniform distribution and prevent overloading. Question 21. The minimum cover depth over distribution pipes in a seepage field is: A) 6 inches B) 12 inches C) 18 inches D) 24 inches Answer: C Explanation: A minimum of 18 inches of cover protects the pipe from surface loads and maintains proper hydraulic head. Question 22. The recommended aggregate size for bedding under distribution pipe is: A) ½-inch to 1-inch stone B) 1-inch to 2-inch stone C) 2-inch to 3-inch stone D) 3-inch to 4-inch stone Answer: B
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Explanation: 1- to 2-inch washed stone provides adequate void space and stability for effluent flow. Question 23. Geotextile fabric placed beneath the gravel in a drain field serves to: A) Increase the hydraulic conductivity of the soil B) Prevent soil particles from clogging the aggregate C) Act as a secondary filter for pathogens D) Provide structural support for the septic tank Answer: B Explanation: Geotextile prevents fine soil from contaminating the gravel, preserving infiltration rates. Question 24. Proper leveling of a distribution box is critical because: A) It determines the aesthetic appearance of the system B) Uneven boxes cause preferential flow, leading to short-circuited lines C) It affects the depth of the septic tank D) It influences the size of the pump required Answer: B Explanation: Level distribution boxes ensure equal hydraulic head to each laterals, preventing overload of any single line.
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C) Cleaning the aerator diffusers and checking blower operation quarterly D) Draining the entire tank every six months Answer: C Explanation: Regular cleaning of diffusers and inspection of the blower are essential to maintain aerobic conditions. Question 28. A buried sand filter must be constructed with a minimum media depth of: A) 12 inches B) 18 inches C) 24 inches D) 36 inches Answer: C Explanation: Illinois requirements call for at least 24 inches of sand media to achieve adequate filtration. Question 29. In a recirculating sand filter, the effluent is: A) Discharged directly to the drain field B) Pumped back through the filter media for additional treatment before discharge C) Mixed with chlorinated water before discharge D) Sent to a secondary septic tank
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Answer: B Explanation: Recirculating systems pass effluent through the sand media multiple times to improve removal of solids and BOD. Question 30. The minimum depth for a waste-stabilization pond (lagoons) in Illinois is: A) 2 ft B) 3 ft C) 4 ft D) 5 ft Answer: C Explanation: A minimum depth of 4 ft ensures sufficient hydraulic retention and prevents surface scum overflow. Question 31. When constructing a waste-stabilization pond, which of the following is required by code? A) A concrete liner only B) A perimeter fence at least 4 ft high C) A floating cover to reduce odor D) An underground aeration system Answer: B Explanation: Ponds must be fenced to restrict access and protect public health.
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Question 34. A lift station in a private sewage system must be equipped with: A) A solar panel backup only B) A float switch, high-water alarm, and a backup power source C) A pressure gauge but no alarm D) Only a manual pump Answer: B Explanation: Lift stations require automatic controls (float switch), alarms for high water, and a backup power source to maintain operation during outages. Question 35. Dosing of effluent is required for which of the following scenarios? A) All systems with a septic tank smaller than 1,000 gallons B) Systems that discharge to a surface water body and have secondary treatment C) Any system using a gravel-based drain field D) Only for systems with a sand filter Answer: B Explanation: Dosing is mandated when secondary treatment is used and the effluent is discharged to surface water to ensure adequate contact time.
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Question 36. The standard chlorine contact time required for disinfection of surface-discharge systems in Illinois is: A) 5 seconds B) 15 seconds C) 30 seconds D) 60 seconds Answer: C Explanation: Illinois regulations require a minimum of 30 seconds of chlorine contact to achieve required pathogen reduction. Question 37. Under the NPDES program, a private sewage system that discharges to a watercourse must obtain: A) A construction permit only B) A National Pollutant Discharge Elimination System (NPDES) permit C) No permit if the flow is less than 100 gpd D) Only a local health department approval Answer: B Explanation: Any discharge to a surface water body requires an NPDES permit, regardless of flow volume. Question 38. Legal disposal of septage in Illinois must be performed by: A) Dumping it on the property’s unused land
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C) Surface-discharge effluent D) Gravel in drain fields Answer: B Explanation: These gases accumulate in confined spaces such as tanks and lift stations, posing explosion and health risks. Question 41. The Illinois Private Sewage Disposal Code is found in which administrative code citation? A) 77 Ill. Adm. Code 905 B) 78 Ill. Adm. Code 1200 C) 75 Ill. Adm. Code 500 D) 80 Ill. Adm. Code 300 Answer: A Explanation: The primary regulatory source is 77 Ill. Adm. Code
Question 42. The Private Sewage Disposal Licensing Act is codified at: A) 225 ILCS 225 B) 220 ILCS 210 C) 230 ILCS 240 D) 215 ILCS 200
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Answer: A Explanation: The licensing framework is located at 225 ILCS 225. Question 43. Illustration G from the IDPH publications is primarily used for: A) Sizing septic tanks B) Demonstrating percolation test procedures C) Layout of distribution boxes D) Design of aerobic treatment plants Answer: B Explanation: Illustration G depicts the correct method for conducting percolation tests. Question 44. Illustration H from the IDPH publications provides: A) A chart for determining septic tank volume based on daily flow B) Soil bearing capacity tables C) A layout for pump station wiring diagrams D) A map of approved disposal sites Answer: A Explanation: Illustration H contains sizing charts used to select appropriate tank capacities.
