Septic Systems cont.

The distribution system acts as the flow manager using gravity to uniformly divide the effluent into a network of perforated drain field pipes that are buried in drain field trenches.  The effluent, drains from the pipes into the trenches, and then seeps into the subsurface soil.  Uneven distribution can overload areas of the drain field, causing the system to fail. 

 The drain field:

The drain field provides the final treatment of the wastewater.  The drain field is typically built as a series of trenches about 1 to 3 feet below ground level.  The drain field must be constructed in permeable soils, have a level bottom, and be 2 or more feet above the groundwater table.   A gravel and pipe system is the most common type of drain field.

Each excavated trench is filled with 6 to 12 inches of gravel.  The gravel exposes a soil infiltrative surface and provides storage for the effluent.   Perforated pipe is laid over the gravel and then covered with synthetic fabric to keep soil and silt out of the system.  The area is then backfilled with soil to cover the system.

The drain field treats the effluent by allowing it to slowly trickle from the pipes out into the gravel and down through the soil. The gravel and the soil act as biological filters absorbing and removing nearly all-harmful substances - such as pollutants, bacteria, and viruses.  Soil particles, particularly clay, chemically attract and hold sewage nutrients, metals, and disease carrying organisms. After passing through this filtering system, the water saturates the ground and at this point we commonly refer to it is groundwater.

Drain field size is determined by the amount of wastewater flow anticipated and the quality of the soil below.  Soil type and the position of the water table also help determine how deep the trenches should be.  A thorough site evaluation is important when the septic system is in the planning phase.  Many septic system failures are the result of poorly sited drain fields.

 

Why Septic Systems Fail

Septic systems fail for a number of reasons.  The most common reasons are abuse and neglect.

1.  We pour and/or flush too much down our drains and toilets

Without realizing it, people sometimes put more water down the drain than the drain can handle and this can cause the system to flood.

2.  Commonly we pour and/or flush “no-no’s”. 

Certain toxics, such as paints, thinners, pesticides, waste oils, and other hazardous chemicals, cannot be treated by the drain field and should never be disposed of through a septic system.

People put harsh and hazardous chemicals into the septic system and these chemicals kill off the friendly bacteria that function to break down solid wastes.  Even small amounts of oven cleaner, degreasers, paints, varnish, thinners, waste oil, photographic solutions, pesticides, and other organic chemicals can destroy the biological digestion-taking place within your system.

People flush plastics, cat box litter, cigarette filters, condoms, tampons, sanitary napkins, paper towels, and facial tissues down the toilet.  These solid materials quickly fill your septic tank and decrease its efficiency.  The only solution here is to have the septic system pumped. These items also clog up the sewer line to the septic tank and may cause wastewater to back up into the house.

People dump grease and fat down the drain.  Grease and fat solidify and accumulate and this commonly contributes to blockages in the system.

3.  Roof drains, basement sump pumps, and other rain water or surface water drainage systems often are too close to the absorption field.  This floods the absorption field with excessive water.

4. Cars and heavy equipment driven over the drain field can ruin the filter pipes.

 

Prolonging the life of your septic system

Here are some simple tips to help you prolong the life of your septic system.

1.  Be conscious of water use 

 Doing Laundry - Do your laundry several times over the week, rather than all on one day.   You can discharge into your septic system up to 53 gallons of water with each wash of laundry.  Doing several loads of laundry in one day it can put considerable stress on your system.  A better practice is to space out your laundry washing throughout the week.

Fix all leaks immediately.  Leaky faucets can drip away 5 gallons of water a day – that’s    1825 gallons of waster water a year.  Fixing the leak will help prolong the life of your septic system and it will save you money on your water bill.

Make sure your toilet is flushing efficiently.   Check to see that it’s full to the full line or flush valve.  Don’t put bricks in the toilet as a water saving measure.  There is a theory that brick displaces the water so you will use less but actually the brick keeps the water from getting to where it needs to go so you may have to flush twice.

Use water saving devices in the shower.  The average showerhead spits out 8 gallons of water a minute.  The water saving showerheads put out 2.5 gallons a minute and still give you a great shower!  You can reduce your water use 60,000 a year by using one of these devices.

2.  Be conscious of what goes into your septic system;

Garbage disposals.  Garbage grinders are NOT recommended for the proper performance of septic systems.  If you use a garbage disposal, you will have to pump your septic system more often than people who don’t use a disposal

Excessively soiled clothes. People working in occupations where their clothes get excessively soiled have a higher than normal percentage of solids in their tanks.

Use a filter on the washing machine.  Lint loosened from clothing during the wash cycle ends up in the septic system.  Lint from synthetic materials (polyester, acrylic, and nylon)   will not break down.

Keep non-degradable and poisons out of the septic tank.  Non-degradable and poisons damage your septic system by killing beneficial microorganisms that live in your tank and work to break down solids, as well they pollute the groundwater.

•   Non-degradable: grease, disposable diapers, plastics

•   Poisons: gasoline, oil, paint, paint thinner, pesticides, antifreeze

Be careful with household cleaning chemicals.   Use bleach, disinfectants, and drain and toilet bowl cleaners sparingly and in accordance with product labels. Take leftover chemicals to hazardous waste collection center for disposal.

3.  Keep roof and driveway drains and basement slump pumps away from the drain field.  

Flooding the drain field with excessive water will keep the soil from naturally cleaning the effluent, leading to groundwater pollution.

4.  Schedule periodic inspections and checkups.

Inspect the septic tank to see if it needs to be pumped or have a service person do the inspection.   Septic tanks need cleaning whenever sludge accumulation in the bottom of the tank exceeds 24 inches in depth or come to about 3 inches from the outlet baffle.  How frequently this will be depends on the size of the tank, the daily flow of sewage into the tank, the number of persons served, and whether or not a garbage grinder is used.  Inspect newly installed tanks at least once every two years to determine how rapidly sludge is accumulating in the tank. Call a certified professional to do the pumping.  A list of certified professionals is available from the Board of Health.

Caution: Never use matches or an open flame when inspecting a septic tank.  Sewer gas is explosive.

Inspect the drainage field.  Sogginess and flooding indicate improper drainage, a clogged system, or excessive water use.  Lush green growth over the drain field and/or sewage odors that persist also indicate a problem

5.    Keep a record of inspections, pumping and maintenance. 

Learn the location of septic system and drain field.  Keep a sketch of the system handy for service visits.  If your system has a flow diversion valve, learn its location and turn it once a year.   Flow diverters can add years to the life of your septic system.

Generally, a good rule of thumb is to think about pumping your septic system every 3 years, but factors unique each household will be cause for variance. 

Consider this:

•   The size of the tank in relation to the number of people living in the house

•   The number of high water devices, like hot tubs, at use in the home.

If two people were living in the house when the septic tank was installed and there were few high water using devices, the septic tank may have taken a long time to fill.  However, if several people now live in the house and they each take a shower a day, and do many loads of laundry, and fill a hot tub – the system will reach it’s capacity in a much shorter period of time.