Rural Sewage

Question 1

When do you need a septic tank, and what is its purpose?

Answer 1

When a building isn’t connected to the city sewage system. It’s used to digest sewage (break down the solids.)

Question 2

What are the two main components of a septic system?

Answer 2

Septic tank, and disposal field.

Question 3

What are the three layers that make up the effluent in a septic tank?

Answer 3

Scum, the top layer, liquid sewage, the middle layer, and sludge, the bottom layer.

Question 4

Where are the anaerobic bacteria present?

Answer 4

In the settled sewage in the tanks.

Question 5

How long should a septic tank be able to hold sewage for?

Answer 5

24 hours.

Question 6

What would you consider when determining the expected daily sewage flow for a septic tank?

Answer 6

Number of people using the tank, cooking habits, soap accumulation from hard water, the use of certain soaps & detergents.

Question 7

What would determine the location of a septic tank?

Answer 7

The soil type, area available, the water table, distance from property lines, water sources & buildings.

Question 8

What types of things do you tank into consideration when sizing a septic field?

Answer 8

-The amount of raw sewage received in a 24 hour period. -Sufficient space for expected accumulation of sludge. -A 50% increase for each garbage grinder. (Garberator). -# of bedrooms. -Size of the residence. -Frost line. -Type of soil. -Water table.

Question 9

What would you do if a septic tank is installed but you find that all the locations for a septic field end up being either too close to a property line or too close to a water source?

Answer 9

Install a pumpout (holding tank). A type of tank that’s pumped out once in a while, no disposal field is used in this situation.

Question 10

What’s the reason for the siphon tank being sized so that it discharges a large amount of effluent at one time?

Answer 10

This ensures that the entire disposal field’s used.

Question 11

What’s the purpose of the outlet tee?

Answer 11

To allow the clearest liquid to enter into the secondary chamber.

Question 12

What type of soil would you use as fill for a disposal field?

Answer 12

You would use a porous soil in order to allow air to reach the gravel bed.

Question 13

How do you test the suitability of the soil for the proposed disposal field?

Answer 13

A percolation test. 2 holes 12” x 12” width, 22” to 32” depth. Test for one hour.

Question 14

Rather than using a distribution box to distribute the clear effluent from a septic tank, you may instead install a header. How should the header be graded?

Answer 14

Level with the branches then sloped away from the header at 2” per 100 ft.

Question 15

What would be required if a private sewage disposal system had the absorption field installed at an elevation above the septic tank?

Answer 15

A pump system should be used.

Question 16

When performing an inspection of a septic tank, you notice that there’s very little scum in the tank. What is the cause?

Answer 16

Too much detergent from a clothes washer, or a broken outlet tee causing scum to leave the septic tank.

Question 17

What’s the most efficient and cost effective system to use for a disposal field containing 600 feet of laterals?

Answer 17

Install a effluent tank and a bell siphon. This will discharge a large amount of effluent at one time.

Question 18

What is the best location for a sewage disposal field?

Answer 18

Elevated and well ventilated.

Question 19

What is the grade of the pipe from a septic tank to the distribution box?

Answer 19

1/4 per foot. 1 in 50.

Question 20

What is the expected grade from the distribution box to the end of the lateral? (The slope of the trench.)

Answer 20

2” per 100 ft.

Question 21

What’s the minimum permissible length of a building drain to a septic tank?

Answer 21

1 meter (3 feet.)

Question 22

If a septic field’s installed, how should the field be sloped?

Answer 22

Away from the house.

Question 23

What is the gravel in a septic tanks main purpose?

Answer 23

For oxygen permeation. (To allow air to go through.)

Question 24

A septic tank uses a subsurface disposal field to distribute effluent evenly. How much backfill (including both aggregate and porous soil) should be placed over the piping in order for oxygen to reach the effluent?

Answer 24

6” of aggregate (gravel) and between 6” to 24” of porous soil.

Question 25

If a condensing boiler or furnace is attached to a septic system, what pH range should the water be neutralized to?

Answer 25

pH - 6 to 9.