South Carolina Septic Tank Installer License
Examination Complete Questions And Detailed
Solutions Latest Update This Year
Q1: South Carolina septic installer license authority?
A. Only EPA federal
B. Only SC Department of Labor
C. SC Department of Environmental Services SCDES (formerly DHEC) - Regulation 61-56 Onsite Wastewater Systems - must be
licensed per SC Code 44-55-1350
D. No license required
Answer & ULTRA-Detailed Rationale:
C. SC Department of Environmental Services SCDES (formerly DHEC) - Regulation 61-56 Onsite Wastewater Systems - must be
licensed per SC Code 44-55-1350
CONCEPT: Who licenses septic installers in SC. CORRECT - A: SC Department of Environmental Services (SCDES) - formerly
DHEC per Regulation 61-56 Onsite Wastewater Systems and SC Code 44-55-1310 et seq. SCDES Bureau of Environmental Health
Services issues installer licenses: requires training, passing exam, proof insurance, continuing education. As of 2024 DHEC split -
environmental becomes SCDES. WHY B WRONG: SC Dept Labor Licensing Regulation LLR licenses contractors (Residential Builders)
but NOT septic installer - septic is SCDES environmental health. Confusing contractor license with installer license is common trap. You
need BOTH if contracting. WHY C WRONG: EPA sets federal guidelines but state administers onsite program under Clean Water Act
delegation. EPA does not license installers directly. Federal vs state trap. WHY D WRONG: License IS required - installing without
SCDES installer license is violation, can be fined, system not approved. Exam tests that license is mandatory. EXAM TIP: Remember
SCDES = septic license, LLR = contractor license. Many need both.
Q2: SC Regulation 61-56 - septic tank minimum size 3-bedroom house?
A. 1000 gallons minimum for 3-bedroom house per Reg 61-56 - 4 bedroom 1250 gal - based on bedrooms not bathrooms
B. 750 gallons Texas size
C. 500 gallons
D. 250 gallons
Answer & ULTRA-Detailed Rationale:
A. 1000 gallons minimum for 3-bedroom house per Reg 61-56 - 4 bedroom 1250 gal - based on bedrooms not bathrooms
CONCEPT: Tank sizing SC vs other states. CORRECT - A: SC Reg 61-56 Table: 3-bedroom = 1000 gal minimum, 4-bedroom = 1250
gal, 5-bedroom = 1500 gal. SC requires larger than Texas 750 gal - based on bedrooms not bathrooms - bedrooms = occupancy
potential. SC uses 2 persons per bedroom. WHY B WRONG: 500 gal far too small - only for 1-bedroom or pump tank. Insufficient
detention time for solids settling - would cause solids washout to drainfield failure. Common undersizing violation. WHY C WRONG: 750
gal is Texas size (30 TAC 285) - SC is larger 1000 gal minimum. Exam intentionally uses Texas numbers to trap those who studied other
state. SC requires more conservative sizing due to soil conditions. WHY D WRONG: 250 gal is dosing tank or garbage - not septic tank
for house. Ridiculously small - would fail immediately. EXAM TIP: Memorize SC sizes: 1-2 bed = 1000? Actually SC 1-2 bed also 1000
gal min - SC min 1000 gal regardless up to 3 beds - unlike Texas 750. SC minimum tank is 1000 gal.
Page 1 | SC SEPTIC INSTALLER - ULTRA RATIONALE - BIG TITLE - 200Q
,Q3: Site evaluation - soil texture and percolation in SC?
A. Site evaluation requires soil borings, soil texture by USDA textural triangle, seasonal high water table, restrictive horizons - SC no
longer uses perc test for conventional - uses soil morphology
B. Only percolation test matters no soil borings
C. No site evaluation needed
D. Only visual from truck
Answer & ULTRA-Detailed Rationale:
A. Site evaluation requires soil borings, soil texture by USDA textural triangle, seasonal high water table, restrictive horizons -
SC no longer uses perc test for conventional - uses soil morphology
CONCEPT: How SC evaluates site - modern soil morphology vs old perc. CORRECT - A: SC Reg 61-56 requires soil borings -
typically 2 borings 6 ft deep or to restrictive horizon, evaluate soil texture by feel (sand, loamy sand, sandy loam etc per USDA),
structure, color, seasonal high water table (SHWT) indicated by gray mottles (redoximorphic features), restrictive horizons clay >40%
rock. SC moved away from perc test for conventional systems - uses soil morphology - perc only for some alternative. WHY B WRONG:
Perc test alone insufficient - SC no longer uses perc for conventional - soil morphology is primary. Old installers who only do perc will fail.
Perc is for repair or alternative only now. WHY C WRONG: Site evaluation mandatory - installing without approved site evaluation and
permit is violation. Must have SCDES permit to construct. WHY D WRONG: Visual from truck insufficient - must dig borings, evaluate
soil profile in pit. Exam tests that you must get out and dig. EXAM TIP: Know redoximorphic features = gray mottles = SHWT.
Q4: Seasonal High Water Table SHWT setback - how determined and setback?
A. Only 1 inch separation
B. SHWT determined by redoximorphic features gray mottles - requires 12 inch separation from bottom of trench to SHWT for
conventional - 6 inch for some alternative with advanced pretreatment
C. SHWT not evaluated
D. No separation needed trench can be in water table
Answer & ULTRA-Detailed Rationale:
B. SHWT determined by redoximorphic features gray mottles - requires 12 inch separation from bottom of trench to SHWT for
conventional - 6 inch for some alternative with advanced pretreatment
CONCEPT: Vertical separation to groundwater - critical for treatment. CORRECT - A: SHWT determined by redoximorphic features -
gray colors with chroma ≤2 with mottles - indicates periodic saturation. Requires 12 inch separation from bottom of conventional trench
to SHWT. For alternative systems with advanced pretreatment, may be 6 inch. This vertical separation provides unsaturated soil
treatment - removes pathogens. WHY B WRONG: No separation means trench in water table - direct groundwater contamination -
violates Reg 61-56 and Clean Water Act. Immediate public health hazard - would be denied permit. WHY C WRONG: 1 inch insufficient -
not enough unsaturated soil for treatment - bacteria travel. Code requires 12 inches minimum. WHY D WRONG: SHWT evaluation
mandatory - must evaluate boring for mottles. Ignoring SHWT causes system failure and well contamination. EXAM TIP: Remember 12
inch conventional, 6 inch some alternative - measure from bottom of trench (not top) to SHWT.
Page 2 | SC SEPTIC INSTALLER - ULTRA RATIONALE - BIG TITLE - 200Q
,Q5: Setback distances SC - well and property line?
A. Well 25 ft only
B. Well 100 ft from septic tank and drainfield per Reg 61-56, property line 5 ft tank 10 ft drainfield, surface water 50-100 ft, building
foundation 5 ft tank
C. No setbacks
D. Well 10 ft from septic
Answer & ULTRA-Detailed Rationale:
B. Well 100 ft from septic tank and drainfield per Reg 61-56, property line 5 ft tank 10 ft drainfield, surface water 50-100 ft,
building foundation 5 ft tank
CONCEPT: Horizontal setbacks - prevent contamination and access. CORRECT - A: SC Reg 61-56 Table: Private well 100 ft from
tank and field, property line 5 ft tank 10 ft field, building foundation 5 ft tank 10 ft field? Actually 5 ft tank 10 ft field to foundation, surface
water (lake stream) 50 ft tank 75-100 ft field, public well 100 ft. These are minimums. WHY B WRONG: 10 ft well to septic would cause
immediate well contamination - pathogens, nitrates - would be public health emergency. Exam uses 10 ft as trap for those confusing with
property line setback. WHY C WRONG: Setbacks exist for public health - no setbacks would allow contamination and legal disputes.
Reg 61-56 Table lists setbacks. WHY D WRONG: 25 ft well setback insufficient - SC requires 100 ft. 25 ft might be surface water
setback for tank in some states but not well in SC. EXAM TIP: Memorize well 100 ft - most tested setback - and that field setback larger
than tank setback for property line.
Q6: Drainfield trench depth and width SC?
A. Trench 6 ft deep
B. Trench width 12 inches only
C. Trench depth max 36 inches bottom, width 24-36 inches typically 36 inches, aggregate 12 inches below pipe and 2 inches above
pipe, cover 12-18 inches
D. No aggregate needed
Answer & ULTRA-Detailed Rationale:
C. Trench depth max 36 inches bottom, width 24-36 inches typically 36 inches, aggregate 12 inches below pipe and 2 inches
above pipe, cover 12-18 inches
CONCEPT: Trench dimensions and construction. CORRECT - A: SC conventional trench: depth bottom max 36 inches below original
grade (to keep in aerobic soil), width 24-36 inches typically 36", aggregate: 12 inches below pipe, 2 inches above pipe per Reg
61-56, pipe 4 inch perforated, cover 12-18 inches soil. Requires level bottom, 1-2% slope? Actually trench bottom level. WHY B
WRONG: 6 ft deep trench would be below aerobic treatment zone, into groundwater, anaerobic - no treatment, plus safety hazard
cave-in. Max 36 inches. WHY C WRONG: Aggregate required for storage and distribution - no aggregate (except chambers) would
cause pipe to sit in soil and clog - aggregate provides storage during dosing and oxygen. WHY D WRONG: 12 inch width too narrow -
insufficient infiltrative surface - would cause premature failure - SC standard 36 inch width for conventional. EXAM TIP: Know 12" below
pipe, 2" above, bottom max 36" deep - common inspection points.
Page 3 | SC SEPTIC INSTALLER - ULTRA RATIONALE - BIG TITLE - 200Q
, Q7: Distribution box D-box requirements?
A. D-box can be tilted 6 inches
B. No D-box needed for all systems
C. One D-box unlimited lines
D. D-box must be level, watertight, equal flow to each line, 5 lines max per D-box, baffle or equal flow device, access to grade
Answer & ULTRA-Detailed Rationale:
D. D-box must be level, watertight, equal flow to each line, 5 lines max per D-box, baffle or equal flow device, access to grade
CONCEPT: Equal distribution critical. CORRECT - A: D-box level within 1 inch, watertight, equal flow to each lateral line, max 5 lines
per D-box per SC, must have baffles or Speed Levelers for equal flow adjustment, access to grade for inspection. If not level, one trench
overloaded, others dry - failure. WHY B WRONG: Tilted 6 inches would send all effluent to lowest line - overload that line hydraulic
failure surface breakout, other lines unused - system failure. Must be level. WHY C WRONG: Unlimited lines per D-box impossible to
balance - SC limits 5 lines max - more lines need second D-box or manifold. WHY D WRONG: D-box needed for gravity distribution to
multiple trenches - unless pressure dosed manifold or single trench. For conventional 3-4 trenches, D-box required. EXAM TIP:
Inspector checks D-box level with level - #1 failure point.
Q8: Pressure dosed vs gravity - when required?
A. Never required gravity always
B. Only for small fields
C. Pressure dosing required when field >2000 sq ft or when using low pressure pipe LPP or when slope >5% or to achieve equal
distribution - pump tank with pump
D. Only for wells
Answer & ULTRA-Detailed Rationale:
C. Pressure dosing required when field >2000 sq ft or when using low pressure pipe LPP or when slope >5% or to achieve
equal distribution - pump tank with pump
CONCEPT: When gravity insufficient. CORRECT - A: Pressure dosing required when: field >2000 sq ft, or low pressure pipe LPP
system, or slope >5% (to prevent downhill line overload), or to achieve equal distribution, or for mound systems. Pump tank with effluent
pump, pressure manifold, small orifices 1/4" in laterals pressurized. WHY B WRONG: Gravity not always sufficient - large fields >2000
sq ft gravity D-box cannot equally distribute - far lines get less - pressure needed for equal. WHY C WRONG: Wells not related -
pressure dosing for field distribution, not well. WHY D WRONG: Opposite - small fields gravity OK, large fields need pressure - not small.
EXAM TIP: Know trigger 2000 sq ft - pressure required beyond.
Q9: SC alternative systems - when conventional not suitable?
A. When SHWT <12 inch, or soil too tight clay >40%, or too fast sand, or slope >25%, or lot too small - alternative: mound, at-grade,
fill, aerobic, drip
B. Only mound exists
C. Alternative never allowed SC
D. Never need alternative conventional works everywhere
Answer & ULTRA-Detailed Rationale:
A. When SHWT <12 inch, or soil too tight clay >40%, or too fast sand, or slope >25%, or lot too small - alternative: mound,
at-grade, fill, aerobic, drip
CONCEPT: When conventional fails site. CORRECT - A: Conventional requires 12" separation to SHWT, suitable soil sandy loam to
sandy clay loam, slope <25%, sufficient area. If not: alternative systems: mound (elevated sand fill), at-grade, fill system, aerobic
treatment unit ATU, drip irrigation. Requires advanced designer. WHY B WRONG: Conventional does NOT work everywhere - SC
coastal high water table, clay soils upcountry - many sites unsuitable - alternative needed. WHY C WRONG: Mound is one alternative
but many others exist - at-grade, fill, ATU, drip - exam tests knowledge of alternatives. WHY D WRONG: Alternatives allowed per Reg
61-56 with SCDES approval and special design - not prohibited. EXAM TIP: Know when to recommend alternative - high water table =
mound.
Page 4 | SC SEPTIC INSTALLER - ULTRA RATIONALE - BIG TITLE - 200Q
Examination Complete Questions And Detailed
Solutions Latest Update This Year
Q1: South Carolina septic installer license authority?
A. Only EPA federal
B. Only SC Department of Labor
C. SC Department of Environmental Services SCDES (formerly DHEC) - Regulation 61-56 Onsite Wastewater Systems - must be
licensed per SC Code 44-55-1350
D. No license required
Answer & ULTRA-Detailed Rationale:
C. SC Department of Environmental Services SCDES (formerly DHEC) - Regulation 61-56 Onsite Wastewater Systems - must be
licensed per SC Code 44-55-1350
CONCEPT: Who licenses septic installers in SC. CORRECT - A: SC Department of Environmental Services (SCDES) - formerly
DHEC per Regulation 61-56 Onsite Wastewater Systems and SC Code 44-55-1310 et seq. SCDES Bureau of Environmental Health
Services issues installer licenses: requires training, passing exam, proof insurance, continuing education. As of 2024 DHEC split -
environmental becomes SCDES. WHY B WRONG: SC Dept Labor Licensing Regulation LLR licenses contractors (Residential Builders)
but NOT septic installer - septic is SCDES environmental health. Confusing contractor license with installer license is common trap. You
need BOTH if contracting. WHY C WRONG: EPA sets federal guidelines but state administers onsite program under Clean Water Act
delegation. EPA does not license installers directly. Federal vs state trap. WHY D WRONG: License IS required - installing without
SCDES installer license is violation, can be fined, system not approved. Exam tests that license is mandatory. EXAM TIP: Remember
SCDES = septic license, LLR = contractor license. Many need both.
Q2: SC Regulation 61-56 - septic tank minimum size 3-bedroom house?
A. 1000 gallons minimum for 3-bedroom house per Reg 61-56 - 4 bedroom 1250 gal - based on bedrooms not bathrooms
B. 750 gallons Texas size
C. 500 gallons
D. 250 gallons
Answer & ULTRA-Detailed Rationale:
A. 1000 gallons minimum for 3-bedroom house per Reg 61-56 - 4 bedroom 1250 gal - based on bedrooms not bathrooms
CONCEPT: Tank sizing SC vs other states. CORRECT - A: SC Reg 61-56 Table: 3-bedroom = 1000 gal minimum, 4-bedroom = 1250
gal, 5-bedroom = 1500 gal. SC requires larger than Texas 750 gal - based on bedrooms not bathrooms - bedrooms = occupancy
potential. SC uses 2 persons per bedroom. WHY B WRONG: 500 gal far too small - only for 1-bedroom or pump tank. Insufficient
detention time for solids settling - would cause solids washout to drainfield failure. Common undersizing violation. WHY C WRONG: 750
gal is Texas size (30 TAC 285) - SC is larger 1000 gal minimum. Exam intentionally uses Texas numbers to trap those who studied other
state. SC requires more conservative sizing due to soil conditions. WHY D WRONG: 250 gal is dosing tank or garbage - not septic tank
for house. Ridiculously small - would fail immediately. EXAM TIP: Memorize SC sizes: 1-2 bed = 1000? Actually SC 1-2 bed also 1000
gal min - SC min 1000 gal regardless up to 3 beds - unlike Texas 750. SC minimum tank is 1000 gal.
Page 1 | SC SEPTIC INSTALLER - ULTRA RATIONALE - BIG TITLE - 200Q
,Q3: Site evaluation - soil texture and percolation in SC?
A. Site evaluation requires soil borings, soil texture by USDA textural triangle, seasonal high water table, restrictive horizons - SC no
longer uses perc test for conventional - uses soil morphology
B. Only percolation test matters no soil borings
C. No site evaluation needed
D. Only visual from truck
Answer & ULTRA-Detailed Rationale:
A. Site evaluation requires soil borings, soil texture by USDA textural triangle, seasonal high water table, restrictive horizons -
SC no longer uses perc test for conventional - uses soil morphology
CONCEPT: How SC evaluates site - modern soil morphology vs old perc. CORRECT - A: SC Reg 61-56 requires soil borings -
typically 2 borings 6 ft deep or to restrictive horizon, evaluate soil texture by feel (sand, loamy sand, sandy loam etc per USDA),
structure, color, seasonal high water table (SHWT) indicated by gray mottles (redoximorphic features), restrictive horizons clay >40%
rock. SC moved away from perc test for conventional systems - uses soil morphology - perc only for some alternative. WHY B WRONG:
Perc test alone insufficient - SC no longer uses perc for conventional - soil morphology is primary. Old installers who only do perc will fail.
Perc is for repair or alternative only now. WHY C WRONG: Site evaluation mandatory - installing without approved site evaluation and
permit is violation. Must have SCDES permit to construct. WHY D WRONG: Visual from truck insufficient - must dig borings, evaluate
soil profile in pit. Exam tests that you must get out and dig. EXAM TIP: Know redoximorphic features = gray mottles = SHWT.
Q4: Seasonal High Water Table SHWT setback - how determined and setback?
A. Only 1 inch separation
B. SHWT determined by redoximorphic features gray mottles - requires 12 inch separation from bottom of trench to SHWT for
conventional - 6 inch for some alternative with advanced pretreatment
C. SHWT not evaluated
D. No separation needed trench can be in water table
Answer & ULTRA-Detailed Rationale:
B. SHWT determined by redoximorphic features gray mottles - requires 12 inch separation from bottom of trench to SHWT for
conventional - 6 inch for some alternative with advanced pretreatment
CONCEPT: Vertical separation to groundwater - critical for treatment. CORRECT - A: SHWT determined by redoximorphic features -
gray colors with chroma ≤2 with mottles - indicates periodic saturation. Requires 12 inch separation from bottom of conventional trench
to SHWT. For alternative systems with advanced pretreatment, may be 6 inch. This vertical separation provides unsaturated soil
treatment - removes pathogens. WHY B WRONG: No separation means trench in water table - direct groundwater contamination -
violates Reg 61-56 and Clean Water Act. Immediate public health hazard - would be denied permit. WHY C WRONG: 1 inch insufficient -
not enough unsaturated soil for treatment - bacteria travel. Code requires 12 inches minimum. WHY D WRONG: SHWT evaluation
mandatory - must evaluate boring for mottles. Ignoring SHWT causes system failure and well contamination. EXAM TIP: Remember 12
inch conventional, 6 inch some alternative - measure from bottom of trench (not top) to SHWT.
Page 2 | SC SEPTIC INSTALLER - ULTRA RATIONALE - BIG TITLE - 200Q
,Q5: Setback distances SC - well and property line?
A. Well 25 ft only
B. Well 100 ft from septic tank and drainfield per Reg 61-56, property line 5 ft tank 10 ft drainfield, surface water 50-100 ft, building
foundation 5 ft tank
C. No setbacks
D. Well 10 ft from septic
Answer & ULTRA-Detailed Rationale:
B. Well 100 ft from septic tank and drainfield per Reg 61-56, property line 5 ft tank 10 ft drainfield, surface water 50-100 ft,
building foundation 5 ft tank
CONCEPT: Horizontal setbacks - prevent contamination and access. CORRECT - A: SC Reg 61-56 Table: Private well 100 ft from
tank and field, property line 5 ft tank 10 ft field, building foundation 5 ft tank 10 ft field? Actually 5 ft tank 10 ft field to foundation, surface
water (lake stream) 50 ft tank 75-100 ft field, public well 100 ft. These are minimums. WHY B WRONG: 10 ft well to septic would cause
immediate well contamination - pathogens, nitrates - would be public health emergency. Exam uses 10 ft as trap for those confusing with
property line setback. WHY C WRONG: Setbacks exist for public health - no setbacks would allow contamination and legal disputes.
Reg 61-56 Table lists setbacks. WHY D WRONG: 25 ft well setback insufficient - SC requires 100 ft. 25 ft might be surface water
setback for tank in some states but not well in SC. EXAM TIP: Memorize well 100 ft - most tested setback - and that field setback larger
than tank setback for property line.
Q6: Drainfield trench depth and width SC?
A. Trench 6 ft deep
B. Trench width 12 inches only
C. Trench depth max 36 inches bottom, width 24-36 inches typically 36 inches, aggregate 12 inches below pipe and 2 inches above
pipe, cover 12-18 inches
D. No aggregate needed
Answer & ULTRA-Detailed Rationale:
C. Trench depth max 36 inches bottom, width 24-36 inches typically 36 inches, aggregate 12 inches below pipe and 2 inches
above pipe, cover 12-18 inches
CONCEPT: Trench dimensions and construction. CORRECT - A: SC conventional trench: depth bottom max 36 inches below original
grade (to keep in aerobic soil), width 24-36 inches typically 36", aggregate: 12 inches below pipe, 2 inches above pipe per Reg
61-56, pipe 4 inch perforated, cover 12-18 inches soil. Requires level bottom, 1-2% slope? Actually trench bottom level. WHY B
WRONG: 6 ft deep trench would be below aerobic treatment zone, into groundwater, anaerobic - no treatment, plus safety hazard
cave-in. Max 36 inches. WHY C WRONG: Aggregate required for storage and distribution - no aggregate (except chambers) would
cause pipe to sit in soil and clog - aggregate provides storage during dosing and oxygen. WHY D WRONG: 12 inch width too narrow -
insufficient infiltrative surface - would cause premature failure - SC standard 36 inch width for conventional. EXAM TIP: Know 12" below
pipe, 2" above, bottom max 36" deep - common inspection points.
Page 3 | SC SEPTIC INSTALLER - ULTRA RATIONALE - BIG TITLE - 200Q
, Q7: Distribution box D-box requirements?
A. D-box can be tilted 6 inches
B. No D-box needed for all systems
C. One D-box unlimited lines
D. D-box must be level, watertight, equal flow to each line, 5 lines max per D-box, baffle or equal flow device, access to grade
Answer & ULTRA-Detailed Rationale:
D. D-box must be level, watertight, equal flow to each line, 5 lines max per D-box, baffle or equal flow device, access to grade
CONCEPT: Equal distribution critical. CORRECT - A: D-box level within 1 inch, watertight, equal flow to each lateral line, max 5 lines
per D-box per SC, must have baffles or Speed Levelers for equal flow adjustment, access to grade for inspection. If not level, one trench
overloaded, others dry - failure. WHY B WRONG: Tilted 6 inches would send all effluent to lowest line - overload that line hydraulic
failure surface breakout, other lines unused - system failure. Must be level. WHY C WRONG: Unlimited lines per D-box impossible to
balance - SC limits 5 lines max - more lines need second D-box or manifold. WHY D WRONG: D-box needed for gravity distribution to
multiple trenches - unless pressure dosed manifold or single trench. For conventional 3-4 trenches, D-box required. EXAM TIP:
Inspector checks D-box level with level - #1 failure point.
Q8: Pressure dosed vs gravity - when required?
A. Never required gravity always
B. Only for small fields
C. Pressure dosing required when field >2000 sq ft or when using low pressure pipe LPP or when slope >5% or to achieve equal
distribution - pump tank with pump
D. Only for wells
Answer & ULTRA-Detailed Rationale:
C. Pressure dosing required when field >2000 sq ft or when using low pressure pipe LPP or when slope >5% or to achieve
equal distribution - pump tank with pump
CONCEPT: When gravity insufficient. CORRECT - A: Pressure dosing required when: field >2000 sq ft, or low pressure pipe LPP
system, or slope >5% (to prevent downhill line overload), or to achieve equal distribution, or for mound systems. Pump tank with effluent
pump, pressure manifold, small orifices 1/4" in laterals pressurized. WHY B WRONG: Gravity not always sufficient - large fields >2000
sq ft gravity D-box cannot equally distribute - far lines get less - pressure needed for equal. WHY C WRONG: Wells not related -
pressure dosing for field distribution, not well. WHY D WRONG: Opposite - small fields gravity OK, large fields need pressure - not small.
EXAM TIP: Know trigger 2000 sq ft - pressure required beyond.
Q9: SC alternative systems - when conventional not suitable?
A. When SHWT <12 inch, or soil too tight clay >40%, or too fast sand, or slope >25%, or lot too small - alternative: mound, at-grade,
fill, aerobic, drip
B. Only mound exists
C. Alternative never allowed SC
D. Never need alternative conventional works everywhere
Answer & ULTRA-Detailed Rationale:
A. When SHWT <12 inch, or soil too tight clay >40%, or too fast sand, or slope >25%, or lot too small - alternative: mound,
at-grade, fill, aerobic, drip
CONCEPT: When conventional fails site. CORRECT - A: Conventional requires 12" separation to SHWT, suitable soil sandy loam to
sandy clay loam, slope <25%, sufficient area. If not: alternative systems: mound (elevated sand fill), at-grade, fill system, aerobic
treatment unit ATU, drip irrigation. Requires advanced designer. WHY B WRONG: Conventional does NOT work everywhere - SC
coastal high water table, clay soils upcountry - many sites unsuitable - alternative needed. WHY C WRONG: Mound is one alternative
but many others exist - at-grade, fill, ATU, drip - exam tests knowledge of alternatives. WHY D WRONG: Alternatives allowed per Reg
61-56 with SCDES approval and special design - not prohibited. EXAM TIP: Know when to recommend alternative - high water table =
mound.
Page 4 | SC SEPTIC INSTALLER - ULTRA RATIONALE - BIG TITLE - 200Q
