Page 1 of 152
New Hampshire Subsurface System Installer
Licensing Exam QUESTIONS AND DETAILED
SOLUTIONS JUST RELEASED
New Hampshire Subsurface System Installer Licensing Exam,
POINT-FORM SUMMARIZED EXAM COVERAGE
NH Jurisdiction and Rule Framework: NH Department of Environmental Services (NHDES) has
primary authority over subsurface wastewater systems (Title 50, Env-Ws 1000 series). Local
municipalities may adopt stricter standards but cannot weaken state rules.
Licensing Classes: Class A (Designer); Class B (Installer); Class D (Pumper). The exam is primarily
for Class B Installers responsible for installation, repair, and replacement of septic systems.
System Components & Definitions: Septic tank (watertight, baffles, inlet/outlet tees),
distribution box (D-box), absorption field (trenches or beds), dosing tank (pump tank), effluent
filter, risers, observation ports.
Soil & Site Evaluation: Deep hole test, percolation test, soil texture (sand, sandy loam, loam,
clay), limiting layers (bedrock, water table, dense layer). Loading rate based on percolation rate.
Trench & Bed Specifications: Minimum trench width (18-36 inches), bottom depth below
original grade, separation distances to groundwater (typically 4 ft seasonal high water table
(SHWT) minimum to bottom of trench). Maximum trench length dependent on flow.
Absorption Area Calculation: Daily design flow (bedrooms x 120 gpd in NH for 3-bedroom
default), loading rate (gallons per day per square foot) from percolation test, required square
footage of absorption area.
System Types: Conventional (gravity), Pressure Distribution (low-pressure dosing) to equalize
flow across trenches, Mound systems (fill system for poor soils), At-grade systems, Drip
Dispersal systems.
Septic Tank Requirements: Minimum size for 3-bedroom home: 1,000 gallons; plus 250 gallons
per additional bedroom. Two-compartment tank preferred for better solids retention. Baffle
requirements (inlet/outlet tees). Working capacity (freeboard).
Effluent Filters: Required in many NH jurisdictions; prevent solids from exiting tank; must be
cleaned periodically.
Distribution Box (D-box): Leveling requirement; ensures equal flow distribution (gravity
systems). Multi-orifice leveling (pipe leveling or orifice shields).
Pressure Distribution: Pump sizing (total dynamic head, friction loss, elevation head). Orifice
sizing (1/4 inch typical). Manifold and lateral layout. Flushing capability.
Trench Construction: Gravel specification (washed 3/4-inch to 2-inch, no fines), pipe placement
(invert at appropriate elevation), backfill (geotextile fabric over gravel, then original soil).
Setback Distances: Property line (usually 10 ft), building foundation (10 ft), wells (50 ft
minimum, 75-100 ft for some), surface water (50-100 ft), water service lines, swimming pools
(25 ft). See Env-Ws 1004.
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Seasonal High Water Table (SHWT) Identification: Redoximorphic features (mottling, gray
colors) indicate seasonal saturation. Minimum vertical separation required (12–24 inches
depending on system type and loading rate).
Percolation Testing Procedure: Test holes (6-8 inch diameter), presoak period (usually 1 hour
for sandy soils, overnight for clay), measure fall over 30 min intervals, report as minutes per
inch.
Loading Rate Determination: Uses percolation rate to assign loading rate (gpd/ft²). Sandy soils:
>60 minutes per inch less loading rate; fast percolation (5 min/inch) requires shallow trenches.
Mound Systems: Fill material (sand, loamy sand) placed on native soil; dispersal bed on top of
fill. Elevation to overcome limiting layers. NHDES mound design criteria.
Operation & Maintenance: Pumping frequency (every 2-5 years depending on usage and tank
size), effluent filter cleaning, inspections at time of real estate transfer (NH RSA 485-A:44-47).
Non-conventional Systems: Wetland disposal (when no other alternative, must demonstrate
site unsuitability), holding tanks (temporary only, generally not allowed for new construction
unless exception). Experimental systems.
Corrections & Repairs: Replacement of failed absorption field, adding reserve area, D-box
repair, septic tank replacement.
Prohibited Discharges: Garage floor drains (oil/gas), sump pumps, water softener backwash
(limited allowances), garbage disposals (increase solids).
Pipe Specifications: Schedule 40 PVC for septic tank to D-box, schedule 20 (thin-wall) for
laterals may be allowed in some jurisdictions but schedule 40 preferred.
Effluent Screens: Required on new systems (NHDES rule Env-Ws 1001.07).
Record Drawings (As-builts): Must be submitted to NHDES and local municipality after
installation, showing all dimensions, locations, depths.
Sanitary Seawall / Privies (non-public water or sewer): Must meet Subsurface System rules if
volume > 500 gpd (residential). Vault privies regulated.
Grease Traps/Interceptors required for commercial kitchens, restaurants.
NH State Building Code – Plumbing Section (IBC/IPC) cross-references septic rules for plumbing
fixtures and drain sizes.
NH Water Supply & Pollution Control Division (WSPCD) – regulatory oversight.
Notice of Intent (NOI) required before construction, approval by local municipality or NHDES
depending on system type/complexity.
Testing and Inspections:
Deep hole – for soil evaluation, limiting layers
Percolation test (perc test) – determines loading rate
Construction inspection – observes proper gravel depth, pipe placement, D-box leveling
Final inspection – as-built approval, backfill verification
Operator Responsibility: Ensure materials meet standards, depth and setback compliance,
proper pipe slopes (1/8 inch per foot typical), watertight joints.
Safety (trench shoring, confined space entry for large tanks) – OSHA applies; installer must
follow safe excavation practices.
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SECTION I: NH RULES, JURISDICTION & LICENSING (1–50)
1. Which New Hampshire agency has primary authority for regulating subsurface wastewater
disposal systems?
A) NH Department of Transportation (NHDOT)
B) NH Department of Environmental Services (NHDES)
C) NH Public Utilities Commission (PUC)
D) Local municipal building department only
Answer: B
Rationale: The NH Department of Environmental Services (NHDES) has statutory authority
under RSA 485-A and administrative rules Env-Ws 1000.
2. Which of the following is a minimum setback distance from a drilled well to any part of a
septic system in NH?
, Page 4 of 152
A) 25 feet
B) 50 feet
C) 75 feet
D) 100 feet
Answer: B
Rationale: Typical well separation distance is 50 feet from drilled well to septic system
components (Env-Ws 1004). Dug wells may require more.
3. The minimum vertical separation distance between the bottom of a conventional gravity
absorption trench and the seasonal high water table is typically:
A) 12 inches
B) 24 inches
C) 36 inches
New Hampshire Subsurface System Installer
Licensing Exam QUESTIONS AND DETAILED
SOLUTIONS JUST RELEASED
New Hampshire Subsurface System Installer Licensing Exam,
POINT-FORM SUMMARIZED EXAM COVERAGE
NH Jurisdiction and Rule Framework: NH Department of Environmental Services (NHDES) has
primary authority over subsurface wastewater systems (Title 50, Env-Ws 1000 series). Local
municipalities may adopt stricter standards but cannot weaken state rules.
Licensing Classes: Class A (Designer); Class B (Installer); Class D (Pumper). The exam is primarily
for Class B Installers responsible for installation, repair, and replacement of septic systems.
System Components & Definitions: Septic tank (watertight, baffles, inlet/outlet tees),
distribution box (D-box), absorption field (trenches or beds), dosing tank (pump tank), effluent
filter, risers, observation ports.
Soil & Site Evaluation: Deep hole test, percolation test, soil texture (sand, sandy loam, loam,
clay), limiting layers (bedrock, water table, dense layer). Loading rate based on percolation rate.
Trench & Bed Specifications: Minimum trench width (18-36 inches), bottom depth below
original grade, separation distances to groundwater (typically 4 ft seasonal high water table
(SHWT) minimum to bottom of trench). Maximum trench length dependent on flow.
Absorption Area Calculation: Daily design flow (bedrooms x 120 gpd in NH for 3-bedroom
default), loading rate (gallons per day per square foot) from percolation test, required square
footage of absorption area.
System Types: Conventional (gravity), Pressure Distribution (low-pressure dosing) to equalize
flow across trenches, Mound systems (fill system for poor soils), At-grade systems, Drip
Dispersal systems.
Septic Tank Requirements: Minimum size for 3-bedroom home: 1,000 gallons; plus 250 gallons
per additional bedroom. Two-compartment tank preferred for better solids retention. Baffle
requirements (inlet/outlet tees). Working capacity (freeboard).
Effluent Filters: Required in many NH jurisdictions; prevent solids from exiting tank; must be
cleaned periodically.
Distribution Box (D-box): Leveling requirement; ensures equal flow distribution (gravity
systems). Multi-orifice leveling (pipe leveling or orifice shields).
Pressure Distribution: Pump sizing (total dynamic head, friction loss, elevation head). Orifice
sizing (1/4 inch typical). Manifold and lateral layout. Flushing capability.
Trench Construction: Gravel specification (washed 3/4-inch to 2-inch, no fines), pipe placement
(invert at appropriate elevation), backfill (geotextile fabric over gravel, then original soil).
Setback Distances: Property line (usually 10 ft), building foundation (10 ft), wells (50 ft
minimum, 75-100 ft for some), surface water (50-100 ft), water service lines, swimming pools
(25 ft). See Env-Ws 1004.
, Page 2 of 152
Seasonal High Water Table (SHWT) Identification: Redoximorphic features (mottling, gray
colors) indicate seasonal saturation. Minimum vertical separation required (12–24 inches
depending on system type and loading rate).
Percolation Testing Procedure: Test holes (6-8 inch diameter), presoak period (usually 1 hour
for sandy soils, overnight for clay), measure fall over 30 min intervals, report as minutes per
inch.
Loading Rate Determination: Uses percolation rate to assign loading rate (gpd/ft²). Sandy soils:
>60 minutes per inch less loading rate; fast percolation (5 min/inch) requires shallow trenches.
Mound Systems: Fill material (sand, loamy sand) placed on native soil; dispersal bed on top of
fill. Elevation to overcome limiting layers. NHDES mound design criteria.
Operation & Maintenance: Pumping frequency (every 2-5 years depending on usage and tank
size), effluent filter cleaning, inspections at time of real estate transfer (NH RSA 485-A:44-47).
Non-conventional Systems: Wetland disposal (when no other alternative, must demonstrate
site unsuitability), holding tanks (temporary only, generally not allowed for new construction
unless exception). Experimental systems.
Corrections & Repairs: Replacement of failed absorption field, adding reserve area, D-box
repair, septic tank replacement.
Prohibited Discharges: Garage floor drains (oil/gas), sump pumps, water softener backwash
(limited allowances), garbage disposals (increase solids).
Pipe Specifications: Schedule 40 PVC for septic tank to D-box, schedule 20 (thin-wall) for
laterals may be allowed in some jurisdictions but schedule 40 preferred.
Effluent Screens: Required on new systems (NHDES rule Env-Ws 1001.07).
Record Drawings (As-builts): Must be submitted to NHDES and local municipality after
installation, showing all dimensions, locations, depths.
Sanitary Seawall / Privies (non-public water or sewer): Must meet Subsurface System rules if
volume > 500 gpd (residential). Vault privies regulated.
Grease Traps/Interceptors required for commercial kitchens, restaurants.
NH State Building Code – Plumbing Section (IBC/IPC) cross-references septic rules for plumbing
fixtures and drain sizes.
NH Water Supply & Pollution Control Division (WSPCD) – regulatory oversight.
Notice of Intent (NOI) required before construction, approval by local municipality or NHDES
depending on system type/complexity.
Testing and Inspections:
Deep hole – for soil evaluation, limiting layers
Percolation test (perc test) – determines loading rate
Construction inspection – observes proper gravel depth, pipe placement, D-box leveling
Final inspection – as-built approval, backfill verification
Operator Responsibility: Ensure materials meet standards, depth and setback compliance,
proper pipe slopes (1/8 inch per foot typical), watertight joints.
Safety (trench shoring, confined space entry for large tanks) – OSHA applies; installer must
follow safe excavation practices.
, Page 3 of 152
SECTION I: NH RULES, JURISDICTION & LICENSING (1–50)
1. Which New Hampshire agency has primary authority for regulating subsurface wastewater
disposal systems?
A) NH Department of Transportation (NHDOT)
B) NH Department of Environmental Services (NHDES)
C) NH Public Utilities Commission (PUC)
D) Local municipal building department only
Answer: B
Rationale: The NH Department of Environmental Services (NHDES) has statutory authority
under RSA 485-A and administrative rules Env-Ws 1000.
2. Which of the following is a minimum setback distance from a drilled well to any part of a
septic system in NH?
, Page 4 of 152
A) 25 feet
B) 50 feet
C) 75 feet
D) 100 feet
Answer: B
Rationale: Typical well separation distance is 50 feet from drilled well to septic system
components (Env-Ws 1004). Dug wells may require more.
3. The minimum vertical separation distance between the bottom of a conventional gravity
absorption trench and the seasonal high water table is typically:
A) 12 inches
B) 24 inches
C) 36 inches
