OSSF INSTALLER 1 TEST | QUESTION
WITH 100% CORRECT ANSWER
What is infiltration - ✔️✔️the entry of water into soil
What is permeability - ✔️✔️the ease at which liquid can move in soil, effected by
properties of soil like aggregation of structural units
What are the 3 properties to characterize soil - ✔️✔️texture, drainage/groundwater
presence and depth/ restrictive horizon
What 2 types of soil are unsuitable - ✔️✔️Class 1a, sand with > 30% gravel and clay
Minimum lot size for OSSF - ✔️✔️1 acre if private water supply
1/2 acre if on city water
Ideal topography for OSSF - ✔️✔️nearly level with gentle slope for rainwater runoff
What % slope is unsuitable for OSSF - ✔️✔️greater than 30%
Where should OSSF NOT be located in regards to topography - ✔️✔️in a depression or
in a complex slope area dissected by gullies and ravines
How can topography be measured - ✔️✔️GPS, laser, optical instrument
What is the surface grade - ✔️✔️the slope of a line expressed as a percent in feet or
inches per 100 feet
Minimum distance for tank and distribution field - ✔️✔️public water well 50/150 feet
public or private water line 10/10 feet
streams, ponds, etc 50/75 feet (except LDP is 25ft)
foundations 5/5 feet
easements 1 foot total
slope where seepage may occur 5/25 feet
Edwards aquifer 50/150 feet
Formula for calculating slope - ✔️✔️difference in elevation over distance multiplied by
100
ex: high point 15 feet, distance 200 feet = 0.75 x 100= 7.5% slope
Formula for drop in inches of pipe, if grade is known - ✔️✔️% slope/100 times distance
ex drop in inches of 0.33% grade over 150 feet
0.33/100 = .0033ft times 150 ft = 0.495 ft
, 0.495 ft x 12inches per foot = 5.9 inches
What should a lot design and installation evaluation include - ✔️✔️lot size, soil and
geologic conditions, topography and slope, setbacks, flood hazards
What is a common reason for soil absorption system failure - ✔️✔️lot size too small
What is a serious threat when a system fails in urban or suburban area? - ✔️✔️threat of
waterborne disease
When minimum lot size cannot be met, system must be designed by - ✔️✔️Professional
Engineer or Professional Sanitarian
What is the most critical soil characteristic - ✔️✔️the ability to absorb wastewater
Where does most of the wastewater treatment occur - ✔️✔️In the soil, not the tank
What is the primary criteria for OSSF selection - ✔️✔️it will function properly
What are some secondary criteria for selecting an OSSF - ✔️✔️cost, minimal
maintenance, simplicity of operation, long term reliability
System loading needs to be equal to or less than what - ✔️✔️System Capacity
Typical wastewater composition - ✔️✔️Total solids 700-1,000 mg/L
Total suspended solids 180-300mg/L
Total Nitrogen 40-50mg/L
Grease 90-110 mg/L
What is the usage rate per day for 3 bedroom house - ✔️✔️300/240 gallons with water
savers
What types of systems can Installer 1 construct and repair? - ✔️✔️standard absorptive
drainfield
unlined ET evaporative drainfield
Leaching chamber drainfield
Pumped effluent drainfield
Gravel less pipe drainfield
Soil substitution
Holding tank
Can an Installer 1 construct a conventional system with a septic tank as pretreatment? -
✔️✔️yes
WITH 100% CORRECT ANSWER
What is infiltration - ✔️✔️the entry of water into soil
What is permeability - ✔️✔️the ease at which liquid can move in soil, effected by
properties of soil like aggregation of structural units
What are the 3 properties to characterize soil - ✔️✔️texture, drainage/groundwater
presence and depth/ restrictive horizon
What 2 types of soil are unsuitable - ✔️✔️Class 1a, sand with > 30% gravel and clay
Minimum lot size for OSSF - ✔️✔️1 acre if private water supply
1/2 acre if on city water
Ideal topography for OSSF - ✔️✔️nearly level with gentle slope for rainwater runoff
What % slope is unsuitable for OSSF - ✔️✔️greater than 30%
Where should OSSF NOT be located in regards to topography - ✔️✔️in a depression or
in a complex slope area dissected by gullies and ravines
How can topography be measured - ✔️✔️GPS, laser, optical instrument
What is the surface grade - ✔️✔️the slope of a line expressed as a percent in feet or
inches per 100 feet
Minimum distance for tank and distribution field - ✔️✔️public water well 50/150 feet
public or private water line 10/10 feet
streams, ponds, etc 50/75 feet (except LDP is 25ft)
foundations 5/5 feet
easements 1 foot total
slope where seepage may occur 5/25 feet
Edwards aquifer 50/150 feet
Formula for calculating slope - ✔️✔️difference in elevation over distance multiplied by
100
ex: high point 15 feet, distance 200 feet = 0.75 x 100= 7.5% slope
Formula for drop in inches of pipe, if grade is known - ✔️✔️% slope/100 times distance
ex drop in inches of 0.33% grade over 150 feet
0.33/100 = .0033ft times 150 ft = 0.495 ft
, 0.495 ft x 12inches per foot = 5.9 inches
What should a lot design and installation evaluation include - ✔️✔️lot size, soil and
geologic conditions, topography and slope, setbacks, flood hazards
What is a common reason for soil absorption system failure - ✔️✔️lot size too small
What is a serious threat when a system fails in urban or suburban area? - ✔️✔️threat of
waterborne disease
When minimum lot size cannot be met, system must be designed by - ✔️✔️Professional
Engineer or Professional Sanitarian
What is the most critical soil characteristic - ✔️✔️the ability to absorb wastewater
Where does most of the wastewater treatment occur - ✔️✔️In the soil, not the tank
What is the primary criteria for OSSF selection - ✔️✔️it will function properly
What are some secondary criteria for selecting an OSSF - ✔️✔️cost, minimal
maintenance, simplicity of operation, long term reliability
System loading needs to be equal to or less than what - ✔️✔️System Capacity
Typical wastewater composition - ✔️✔️Total solids 700-1,000 mg/L
Total suspended solids 180-300mg/L
Total Nitrogen 40-50mg/L
Grease 90-110 mg/L
What is the usage rate per day for 3 bedroom house - ✔️✔️300/240 gallons with water
savers
What types of systems can Installer 1 construct and repair? - ✔️✔️standard absorptive
drainfield
unlined ET evaporative drainfield
Leaching chamber drainfield
Pumped effluent drainfield
Gravel less pipe drainfield
Soil substitution
Holding tank
Can an Installer 1 construct a conventional system with a septic tank as pretreatment? -
✔️✔️yes
