Download Alabama Onsite Wastewater Board (AOWB) Installer License QUESTIONS AND CORRECT ANSWERS PL and more Exams Water and Wastewater Engineering in PDF only on Docsity!
Alabama Onsite Wastewater Board (AOWB) Installer License
QUESTIONS AND CORRECT ANSWERS PLUS RATIONALES 2025
- What is the minimum setback distance required between an onsite wastewater system and a private well in Alabama? 100 feet This is the standard minimum distance set by AOWB to prevent contamination of drinking water sources.
- Which soil type is generally most suitable for a conventional septic system? Loamy sand Loamy sand allows for adequate percolation and filtration, preventing ponding and contamination.
- How often should a septic tank be pumped, according to best practice guidelines? Every 3 to 5 years Routine pumping prevents solids from entering the drainfield and extends system life.
- What must be obtained before installing an onsite wastewater system in Alabama? A permit from the county health department Permits ensure proper design, siting, and installation in compliance with state regulations.
- Who is responsible for the final inspection of a new onsite wastewater system in Alabama? Local health department official They verify the system meets code before it’s covered or used.
- What is the minimum depth for burying a septic tank inlet pipe? At least 6 inches below frost line This prevents freezing, which could block flow into the tank.
- What is the purpose of a distribution box? To evenly distribute effluent to all drainfield lines Even distribution prevents overloading one area, which can cause failure.
- When backfilling a septic tank, what material should be used? Clean soil free of rocks and debris This reduces the risk of puncturing or damaging the tank.
- What does a percolation test determine? Soil absorption rate It measures how quickly the soil can absorb effluent. 10.What is the typical design life of a properly maintained drainfield? 20 to 30 years Good maintenance and usage habits can maximize system longevity. 11.What type of onsite system is recommended for areas with high water tables? Elevated mound system Mound systems provide added separation from the water table.
19.Which inspection must occur before covering an installed system? Pre-cover inspection This verifies correct installation before it’s buried. 20.Which pipe material is commonly used for septic tank inlet and outlet pipes? PVC PVC is durable, corrosion-resistant, and cost-effective. 21.When should effluent filters be cleaned? At least annually Regular cleaning prevents clogs that can cause backups. 22.What factor determines minimum lot size for onsite systems? Soil conditions and percolation rate Poor soils require larger lots to accommodate larger drainfields. 23.What should be done if a system alarm activates? Check system components immediately Ignoring alarms can lead to system damage or failure. 24.What is the required separation between the drainfield trench bottom and the seasonal high water table? At least 2 feet This prevents groundwater contamination. 25.Who is responsible for educating the homeowner about system maintenance? The licensed installer Installers must inform owners to promote proper use and care.
26.How wide should a typical drainfield trench be? 18 to 36 inches This range allows for adequate distribution and soil contact. 27.What is a sign of a clogged effluent filter? Slow draining fixtures This indicates the filter needs cleaning to restore flow. 28.Which document must be kept on site during installation? Approved permit and plans Inspectors need to verify compliance with design specs. 29.What does a distribution box need to be set on? Level, stable base A level box ensures even flow to all lines. 30.How often should risers and lids be inspected? Annually Inspections prevent unauthorized access and damage. 31.What should be done if a tank is installed in clay soils? Use larger drainfield area Clay soils drain slower, requiring more surface area. 32.What is the purpose of inspection ports? Allow access to monitor system performance They make checking for ponding or clogs easier.
40.What must be done if bedrock is encountered close to the surface? Install an alternative system Mounds or aerobic units can provide needed separation. 41.What should be done with excavation spoils? Spread and compact away from system This prevents settling that could damage pipes. 42.What is the required clearance from a drainfield to a property line? 10 feet This prevents encroachment and drainage issues. 43.Which of the following is NOT allowed near a drainfield? Parking vehicles Heavy loads can crush pipes and compact soil. 44.What must be done if effluent backs up into the house? Check for clogs and pump the tank if needed Addressing blockages quickly prevents damage. 45.What kind of bacteria breaks down solids in the tank? Anaerobic bacteria They thrive without oxygen inside the tank. 46.What is the purpose of a dosing system? Distribute effluent evenly in timed intervals This prevents overloading the soil at once.
47.Which part of a system must be watertight? Septic tank and connections Leaks can cause contamination or system failure. 48.What is the minimum fall per foot for a building sewer line? 1/8 inch per foot This provides proper flow without solids settling. 49.When is a pump required in an onsite system? When the drainfield is uphill from the tank Pumps lift effluent to the higher elevation. 50.What must be done after a tank is installed but before it’s backfilled? Fill tank with water This prevents shifting or damage during backfill. 51.Which household product should be minimized to protect a septic system? Bleach Excessive bleach kills beneficial bacteria needed for treatment. 52.What is the best way to locate an old septic tank? Use a probe rod or metal detector These tools help locate buried tanks without unnecessary digging. 53.What is the effect of using a garbage disposal with a septic system? Increases solids load More solids lead to more frequent pumping needs.
61.What type of soil is most limiting for absorption? Clay Clay drains poorly and can cause ponding. 62.What is one advantage of an aerobic treatment unit? Produces higher quality effluent Treated effluent can be used in restrictive soils. 63.What is the main concern with sandy soils? Rapid percolation with limited filtration Too-fast drainage can lead to groundwater contamination. 64.What must be avoided during excavation in wet soil? Smearing trench walls Smearing seals soil pores, reducing infiltration. 65.What should be done if trench sides smear? Scarify trench walls Loosening soil restores infiltration capacity. 66.What type of inspection is required for an aerobic unit? Routine maintenance and monitoring Aerobic units need regular service to function properly. 67.What is the main cause of drainfield failure? Excessive solids or grease entering the field This clogs the soil and prevents proper drainage.
68.What test helps determine water table depth? Observation well These wells monitor seasonal fluctuations. 69.What is the function of a curtain drain? Redirect groundwater away from the drainfield This prevents soil saturation. 70.Which system component must be accessible for inspection? Tank lids and inspection ports Access is needed for service and pumping. 71.What must be used when a tank is set in high groundwater? Anti-buoyancy measures These prevent tanks from floating. 72.What is one sign that an aerobic system needs service? Odor near the system Strong odors may mean the system isn’t treating properly. 73.What is the best way to locate a drainfield? Check property records and site plans Permits often show drainfield layout. 74.What must be used if a drainfield replacement is needed? Health department approved design Replacement systems must meet current code.
82.When should a replacement area be planned? During initial site design Future failure areas must be reserved. 83.What is the main function of lateral pipes? Deliver effluent to soil evenly They disperse flow throughout the drainfield. 84.What should be avoided when compacting backfill? Heavy equipment directly over the system This could damage pipes or tanks. 85.What is the key factor in selecting a pump size? Head pressure and flow rate Pumps must match the system’s lift and capacity needs. 86.When should a septic tank be watertight tested? Before backfilling Leaks can be fixed before final installation. 87.What should be installed to prevent tank floats from tangling? Pump rail system Guides keep floats and pumps in place. 88.What should be checked during final inspection? System location, depth, and setbacks This ensures code compliance.
89.How should drainfield trenches be spaced? At least 6 feet apart This prevents soil saturation overlap. 90.What is the required distance from a septic tank to a water supply line? 10 feet Protects potable water from contamination. 91.When is pressure dosing preferred? When site has irregular slopes or restrictive soils Pressure dosing ensures even distribution. 92.What is the best practice for roof drains near a drainfield? Divert away from drainfield Excess water can flood the system. 93.Who must approve a variance to standard setback distances? Local health department Variance must be documented and justified. 94.What should be used when digging near utilities? Hand digging or soft digging tools Prevents accidental damage or strikes. 95.What is the effect of compaction on drainfield soils? Reduces permeability Compaction limits soil’s ability to absorb effluent.
- What is the main hazard when working inside a tank? Toxic gas exposure Hydrogen sulfide can be deadly without ventilation.
- What is the function of an effluent filter? Trap solids before they reach the drainfield Reduces clogs and prolongs drainfield life.
- What does “perc rate” mean? Minutes per inch of drop in water level Indicates how quickly soil absorbs water.
- What is required when designing a system on a slope? Terracing or step-down trenches Prevents runoff and ensures proper flow.
- What should be done if bedrock is shallow? Install a mound or alternative system Provides needed soil depth for treatment.
- What is the consequence of undersized drainfields? System overload and surfacing effluent Sizing must match usage and soil capacity.
- What type of vegetation is ideal over a drainfield? Grass cover Grass helps with evapotranspiration and prevents erosion.
- What is the minimum slope for a force main? No slope required Force mains are pressurized; slope is unnecessary.
- What is the typical use of dosing tanks? Store and pump effluent at intervals Improves distribution and soil recovery time.
- Who must license an installer? Alabama Onsite Wastewater Board Work must be done by licensed professionals.
- What is the biggest risk of installing in saturated soil? Smearing and sealing of soil pores Reduces infiltration capacity.
- How often must aerobic units be inspected? At least quarterly They require more frequent checks than conventional systems.
- What is a “reserve area”? Land set aside for future replacement Ensures space if system fails.
- What is the purpose of a flow equalization tank? Balance surges in wastewater flow Protects downstream components.
- How can installers prevent backfill damage to tanks? Use staged backfilling and compacting Even loading prevents shifting or cracks.
- What is the most common sign of a clogged drainfield? Wet spots and ponding in the yard Indicates system overload or soil failure.
- What is required to dispose of septage? Licensed waste hauler or disposal facility Improper disposal is illegal and unsafe.
- What should be avoided in the drainfield area? Permanent structures Building over fields restricts access and damages pipes.
- What does “site limiting condition” mean? Any factor restricting a standard system May require alternative design.
- Who sets soil suitability standards? Alabama Department of Public Health Ensures statewide consistency.
- How should installer records be kept? Maintain for at least two years AOWB requires records for compliance and future reference.
- What is the required setback from a septic tank to a property line? 5 feet This protects neighboring properties and easements.
- What is the most important maintenance task for homeowners? Pump the tank regularly Pumping removes solids before they clog the drainfield.
- What is the purpose of using observation ports in a drainfield? Check for ponding or backup They help monitor system performance.
- What must be done before installing any system components? Verify design matches site conditions Site changes may need plan adjustments.
- What kind of pipe is best for pressurized laterals? PVC Schedule 40 It’s durable and pressure-rated.
- What is the minimum slope for gravity flow sewer lines? 1/8 inch per foot Ensures solids don’t settle out.
- When must an installer call for an inspection? Before covering the system Verifies compliance with design and code.
