OSSF Module 6 Questions and Answers
100% Correct | Updated 2024
Disposal and treatment selection criteria - ANSWER Primary - OSSF must
function properly under specific soil and other conditions present of the site.
Secondary - Cost, Minimal maintenance, simplicity of operation, long-term
reliability
Table XIII:
http://txrules.elaws.us/Gateway/Html//TITLE30/PART1/CHAPTER285/SUBCHAPTE
RI/285.91/2018-11-29/HTML/30_0285_0091-21.html
Installer I is able to construct and repair these systems - ANSWER Standard
Absorptive drainfield
ET (unlined) evaporation drainfield
Pumped effluent drainfields
Gravelless pipe drainfield
Soil Substitution
*can install holding tank but is extremely rare
See Table IX
http://txrules.elaws.us/Gateway/Html//TITLE30/PART1/CHAPTER285/SUBCHAPTE
RI/285.91/2018-11-29/HTML/30_0285_0091-22.html
,Piping in a house sewer - ANSWER Pipe is to be constructed of cast iron,
ductile iron, polyvinyl chloride (PVC) Schedule 40, standard dimension ratio (SDR)
or other approved material.
Pipes installed beneath driveways, sidewalks, or up to surface improvements must
use sch. 80 PVC or sleeved sch. 40 PVC
Pipe from house to treatment unit must be as large as the building drain, but no
smaller than 3 inch diameter
Line must be watertight and a two-way cleanout plug must be provided between
the building and the septic system
Slope of house sewer - ANSWER No less than 1/8 inch fall per foot of pipe. The
stub out location shall be at the highest possible elevation
Cleanouts - ANSWER a two-way cleanout plug must be provided between the
building and the septic system.
Additional cleanout shall be provided upstream and within 5 feet of every 90
degree bend and at least one cleanout every 100 feet
Septic tank - ANSWER Widely used on-site treatment option in Texas.
,Buried watertight tanks designed and constructed to receive wastewater from a
home or a business. They separate solids from liquids, provide limited anaerobic
digestion of organic matter, store solids, and allow the clarified liquid to discharge
for further treatment and disposal.
Settable solids and sludge settle at the bottom of the tank and accumulate. Scum
and other light material rise to the top
Performance of Septic Tanks - ANSWER Primary treatment, only partially treats
effluent and potential for disease transmission is virtually unchanged from raw
wastewater
They should remove 60-70% of suspended solids and oil and grease present in raw
wastewater
At best only 30-40% of BOD is removed
Calculating size of tank - ANSWER must be a 2 or 3 compartment design with 2
or 3 tanks in a series or a single structure with multiple compartments.
-First compartment must contain 1/2 to 2/3 of the required volume for a 2
compartment tank
-first compartment must contain 1/3 of required volume , but no less than 500
gallons
Tanks are sized to provide approximately 2-3 days detention time. The septic tank
volume is the liquid volume only.
, Usefulness of the septic tank system decreases as the size of the establishment
increases
See Table II in 30 TAC 285.91
http://txrules.elaws.us/Gateway/codepdf//TITLE30/PART1/CHAPTER285/SUBCHA
PTERI/285.91/2018-11-29/PDF/201206290-2.pdf
Location of Septic Tank - ANSWER With respect to the home or building is
usually determined by the slope of the land and the bathroom and kitchen
plumbing stub out from the home.
In new construction establish the best location depending on the soil for the
septic tank and disposal field, then locate the house and the plumbing within
Table X shows minimum distances
Locate and attempt to avoid public water lines, if it cannot be avoided, follow
rules to minimize potential of contamination
Avoid high traffic areas as excessive loads could damage the areas. Locate tank
near a route where it is easily accessible for maintenance.
Also consider future home expansion and additions
Materials of a tank - ANSWER Sturdy, watertight construction,; appropriate
materials include:
-steel-reinforced, poured in place concrete
100% Correct | Updated 2024
Disposal and treatment selection criteria - ANSWER Primary - OSSF must
function properly under specific soil and other conditions present of the site.
Secondary - Cost, Minimal maintenance, simplicity of operation, long-term
reliability
Table XIII:
http://txrules.elaws.us/Gateway/Html//TITLE30/PART1/CHAPTER285/SUBCHAPTE
RI/285.91/2018-11-29/HTML/30_0285_0091-21.html
Installer I is able to construct and repair these systems - ANSWER Standard
Absorptive drainfield
ET (unlined) evaporation drainfield
Pumped effluent drainfields
Gravelless pipe drainfield
Soil Substitution
*can install holding tank but is extremely rare
See Table IX
http://txrules.elaws.us/Gateway/Html//TITLE30/PART1/CHAPTER285/SUBCHAPTE
RI/285.91/2018-11-29/HTML/30_0285_0091-22.html
,Piping in a house sewer - ANSWER Pipe is to be constructed of cast iron,
ductile iron, polyvinyl chloride (PVC) Schedule 40, standard dimension ratio (SDR)
or other approved material.
Pipes installed beneath driveways, sidewalks, or up to surface improvements must
use sch. 80 PVC or sleeved sch. 40 PVC
Pipe from house to treatment unit must be as large as the building drain, but no
smaller than 3 inch diameter
Line must be watertight and a two-way cleanout plug must be provided between
the building and the septic system
Slope of house sewer - ANSWER No less than 1/8 inch fall per foot of pipe. The
stub out location shall be at the highest possible elevation
Cleanouts - ANSWER a two-way cleanout plug must be provided between the
building and the septic system.
Additional cleanout shall be provided upstream and within 5 feet of every 90
degree bend and at least one cleanout every 100 feet
Septic tank - ANSWER Widely used on-site treatment option in Texas.
,Buried watertight tanks designed and constructed to receive wastewater from a
home or a business. They separate solids from liquids, provide limited anaerobic
digestion of organic matter, store solids, and allow the clarified liquid to discharge
for further treatment and disposal.
Settable solids and sludge settle at the bottom of the tank and accumulate. Scum
and other light material rise to the top
Performance of Septic Tanks - ANSWER Primary treatment, only partially treats
effluent and potential for disease transmission is virtually unchanged from raw
wastewater
They should remove 60-70% of suspended solids and oil and grease present in raw
wastewater
At best only 30-40% of BOD is removed
Calculating size of tank - ANSWER must be a 2 or 3 compartment design with 2
or 3 tanks in a series or a single structure with multiple compartments.
-First compartment must contain 1/2 to 2/3 of the required volume for a 2
compartment tank
-first compartment must contain 1/3 of required volume , but no less than 500
gallons
Tanks are sized to provide approximately 2-3 days detention time. The septic tank
volume is the liquid volume only.
, Usefulness of the septic tank system decreases as the size of the establishment
increases
See Table II in 30 TAC 285.91
http://txrules.elaws.us/Gateway/codepdf//TITLE30/PART1/CHAPTER285/SUBCHA
PTERI/285.91/2018-11-29/PDF/201206290-2.pdf
Location of Septic Tank - ANSWER With respect to the home or building is
usually determined by the slope of the land and the bathroom and kitchen
plumbing stub out from the home.
In new construction establish the best location depending on the soil for the
septic tank and disposal field, then locate the house and the plumbing within
Table X shows minimum distances
Locate and attempt to avoid public water lines, if it cannot be avoided, follow
rules to minimize potential of contamination
Avoid high traffic areas as excessive loads could damage the areas. Locate tank
near a route where it is easily accessible for maintenance.
Also consider future home expansion and additions
Materials of a tank - ANSWER Sturdy, watertight construction,; appropriate
materials include:
-steel-reinforced, poured in place concrete
