IL SEPTIC INSTALLERS EXAM
QUESTIONS AND ANSWERS
Public Sewer Connection - Answer-Private residence must connect if w/in 300' or for any commercial
bldg. w/in 300' that has flows less than 1500 gpd. Commercial w/ flows = to or greater than 1500 gpd
must connect if sewer is w/in 1000'.
Unless physical barrier, ordinance, or cannot be done w/ individual line (4" line)-then PSD system is OK.
Acceptable Pipe Materials - Answer-Vitrified clay, ductile iron, or plastic.
Anything after the tank or from distribution box has to be vitrified clay or plastic.
Schedule 40 or Greater - Answer-under roads, driveways, or parking areas
Gravity Slope - Answer-Diameter: 4" pipe + min. slope of 12" per 100'
Building sewers in excess of 50' should have what? - Answer-A C/O @ least every 50' from building to
tank, distribution box, or ATU
Creviced Limestone Formation - Answer-SS system cannot be installed where bottom of system is less
than 4' from top of limestone
,If limestone is known to be present a soil test must be done @ least 4' deeper than where the bottom of
the trench will be
How far away can quick disconnect be? - Answer-no more than 50' away from the device & w/in sight of
Experimental Use Permits - Answer-min. of 10 experimental systems installed b4 unconditional approval
granted. Permit valid for 2 yrs & evaluated @ end of 2 yrs.
2 options for garbage grinders - Answer-1. solids retention tank btwn WW source & septic tk. for kitchen
waste only. Needs to be 50% of the size of the designed septic tank w/ a min. of 500 gals.
2. A septic tank receiving all flows sized as 50% of the septic tank size + septic tank size. i.e., septic tk =
1500 gals. /2 = 750 + 1500 = 2250 (would need 2500 gal tk)
How long should a homeowner keep maint. records for their system? - Answer-the life of the system
When should the 1st maintenance of a septic tank after installation be completed for a residence? -
Answer-Prior to or within 3 yrs. After initial inspection it can be done once every 5 yrs. Can be done by
everyone + homeowner
If sludge layer /suspended solids are greater than 33% . . . - Answer-Must pump tank and perform
maintenance
When should a septic system be evaluated initially after installation for a non-residential bldg? - Answer-
prior to or w/in 3 yrs. After that it should be done @ least every 3 yrs.
Owner cannot do. has to be engineer, env. health practitioner, member of dept, HD, or septic contractor
Aerobic Treatment Unit Evaluations - Answer-1 every 6 mos @ least (same ppl) + HOMEOWNER as long
as they follow manufacturer's requirements & proper maintenance
, What is the maint. schedule for SFs & WSPs w/ surface discharges? - Answer-@ least 1 per yr. + H.O. if
rules r followed. Pumped when solids & scum greater than 33%
Can a H.O. install & maintain a septic system on his/her property? - Answer-Yes
Who can perform the excavation for a septic system? - Answer-A licensed installer (employee while
supervised) or the property owner.
What is the min. size tank for flows UP TO 500 gpd? - Answer-750 gals.
If flows are greater than 500 gpd, how do you size the tank? - Answer-Tank size should be = to @ least
1.5x the estimated sewage flow
How do you size a tank(s) for flows greater than 1350 gpd? - Answer-U must use multiple tks. in a series
or multiple compartment tks. where the 1st tank or the 1st comp. in a multicomp. tk. is 1/2-2/3 of the
total required capacity. of the tank(s)
How do you size the tank for a raised filter bed for a residence? - Answer-It has to be an NSF 40 batch
treatment system. The aeration tank has to be 2x the daily flow
How do you size the tank for a RFB for a commercial bldg? - Answer-The aeration tk. has to be 3x the
daily flow.
Multiple tanks in a series connected @ btm for flow equalization can be used
How are RFB sidewalls sized? - Answer-3:1 ratio
How are distribution lines for RFBs? - Answer-4" perforated pipe on 15" centers
QUESTIONS AND ANSWERS
Public Sewer Connection - Answer-Private residence must connect if w/in 300' or for any commercial
bldg. w/in 300' that has flows less than 1500 gpd. Commercial w/ flows = to or greater than 1500 gpd
must connect if sewer is w/in 1000'.
Unless physical barrier, ordinance, or cannot be done w/ individual line (4" line)-then PSD system is OK.
Acceptable Pipe Materials - Answer-Vitrified clay, ductile iron, or plastic.
Anything after the tank or from distribution box has to be vitrified clay or plastic.
Schedule 40 or Greater - Answer-under roads, driveways, or parking areas
Gravity Slope - Answer-Diameter: 4" pipe + min. slope of 12" per 100'
Building sewers in excess of 50' should have what? - Answer-A C/O @ least every 50' from building to
tank, distribution box, or ATU
Creviced Limestone Formation - Answer-SS system cannot be installed where bottom of system is less
than 4' from top of limestone
,If limestone is known to be present a soil test must be done @ least 4' deeper than where the bottom of
the trench will be
How far away can quick disconnect be? - Answer-no more than 50' away from the device & w/in sight of
Experimental Use Permits - Answer-min. of 10 experimental systems installed b4 unconditional approval
granted. Permit valid for 2 yrs & evaluated @ end of 2 yrs.
2 options for garbage grinders - Answer-1. solids retention tank btwn WW source & septic tk. for kitchen
waste only. Needs to be 50% of the size of the designed septic tank w/ a min. of 500 gals.
2. A septic tank receiving all flows sized as 50% of the septic tank size + septic tank size. i.e., septic tk =
1500 gals. /2 = 750 + 1500 = 2250 (would need 2500 gal tk)
How long should a homeowner keep maint. records for their system? - Answer-the life of the system
When should the 1st maintenance of a septic tank after installation be completed for a residence? -
Answer-Prior to or within 3 yrs. After initial inspection it can be done once every 5 yrs. Can be done by
everyone + homeowner
If sludge layer /suspended solids are greater than 33% . . . - Answer-Must pump tank and perform
maintenance
When should a septic system be evaluated initially after installation for a non-residential bldg? - Answer-
prior to or w/in 3 yrs. After that it should be done @ least every 3 yrs.
Owner cannot do. has to be engineer, env. health practitioner, member of dept, HD, or septic contractor
Aerobic Treatment Unit Evaluations - Answer-1 every 6 mos @ least (same ppl) + HOMEOWNER as long
as they follow manufacturer's requirements & proper maintenance
, What is the maint. schedule for SFs & WSPs w/ surface discharges? - Answer-@ least 1 per yr. + H.O. if
rules r followed. Pumped when solids & scum greater than 33%
Can a H.O. install & maintain a septic system on his/her property? - Answer-Yes
Who can perform the excavation for a septic system? - Answer-A licensed installer (employee while
supervised) or the property owner.
What is the min. size tank for flows UP TO 500 gpd? - Answer-750 gals.
If flows are greater than 500 gpd, how do you size the tank? - Answer-Tank size should be = to @ least
1.5x the estimated sewage flow
How do you size a tank(s) for flows greater than 1350 gpd? - Answer-U must use multiple tks. in a series
or multiple compartment tks. where the 1st tank or the 1st comp. in a multicomp. tk. is 1/2-2/3 of the
total required capacity. of the tank(s)
How do you size the tank for a raised filter bed for a residence? - Answer-It has to be an NSF 40 batch
treatment system. The aeration tank has to be 2x the daily flow
How do you size the tank for a RFB for a commercial bldg? - Answer-The aeration tk. has to be 3x the
daily flow.
Multiple tanks in a series connected @ btm for flow equalization can be used
How are RFB sidewalls sized? - Answer-3:1 ratio
How are distribution lines for RFBs? - Answer-4" perforated pipe on 15" centers
