Module 6 Final Review Exam Questions
With Guaranteed Pass Solutions.
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/SUBCHAPTERI/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/SUBCHAPTERI/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/
SUBCHAPTERI/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
-steel-reinforced, pre-cast concrete
-fiberglass
-reinforced plastic polyethylene
-Other materials approved by TCEQ
Metal tanks are prohibited due to corrosion; Other unacceptable materials include cinder blocks and
wood.
tanks exhibiting obvious leaks or defects should not be used, but condensation at construction joints is
acceptable.
Poured in place concrete tanks must be designed by a PE with relevant experience
All pre-cast tanks should be clearly marked, tagged, or stamped with manufacturer's name and tank
capacity
Internal Design of the tank - Answer 2 or 3 compartment tanks are required in Texas for septic system.
The first compartment will be as large or larger than the 2nd compartment, but no less than 500 gallons
Three tanks in a series may be used but the first tank must be 1/3 of the total volume.
Baffles should be used to separate compartments
Most settable solids will be removed in the first chamber.
Design Requirements (two compartment) - Answer Inflow line at least 3 inches above tank operating
level
With Guaranteed Pass Solutions.
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/SUBCHAPTERI/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/SUBCHAPTERI/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/
SUBCHAPTERI/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
-steel-reinforced, pre-cast concrete
-fiberglass
-reinforced plastic polyethylene
-Other materials approved by TCEQ
Metal tanks are prohibited due to corrosion; Other unacceptable materials include cinder blocks and
wood.
tanks exhibiting obvious leaks or defects should not be used, but condensation at construction joints is
acceptable.
Poured in place concrete tanks must be designed by a PE with relevant experience
All pre-cast tanks should be clearly marked, tagged, or stamped with manufacturer's name and tank
capacity
Internal Design of the tank - Answer 2 or 3 compartment tanks are required in Texas for septic system.
The first compartment will be as large or larger than the 2nd compartment, but no less than 500 gallons
Three tanks in a series may be used but the first tank must be 1/3 of the total volume.
Baffles should be used to separate compartments
Most settable solids will be removed in the first chamber.
Design Requirements (two compartment) - Answer Inflow line at least 3 inches above tank operating
level
