EldredgeSeptic.com

Homeowners Guide to On-Lot Sewage

Systems

Jeremiah Eldredge Septic Management Services

EldredgeSeptic.com

What is an on-lot sewage system?

•On-lot sewage systems are composed of two primary parts:• Septic tanks or an aerobic tank• Remove the settleable and floatable solids from the wastewater

• An absorption area• Utilizes the ability of the soil to filter and treat the remaining

effluent before it reaches the water table

•Proper maintenance of the septic tanks or aerobic tank will prevent more costly problems with the absorption area

EldredgeSeptic.com

Sources of household sewage

Household sewage is a combination of wastewater from toilets, showers, tubs, sinks, washing machines, dishwashers, water softeners and garbage disposals

EldredgeSeptic.com

Types of on-lot sewage systems

The basic types of on-lot systems in eastern PA are:• Cesspool• Septic tanks with seepage pit• Septic tanks or aerobic tank with seepage bed• Septic tanks or aerobic tank tank with standard trenches• Septic tanks or aerobic tank with elevated sand mound• Other technologies not listed here are used in special

circumstances

EldredgeSeptic.com

Cesspools and Septic Tanks with Seepage Pits

•Cesspools and septic tanks with seepage pits are no longer permitted for installation

•Many older homes with systems installed prior to 1970 may have these systems in use

EldredgeSeptic.com

Cesspools

•Cesspools are constructed of open-jointed walls (concrete block or stone) and open bottoms•The solids in the wastewater settle to the bottom,

while the effluent seeps through the jointed walls and bottom

EldredgeSeptic.com

Septic Tanks with Seepage Pits

•The septic tank provides for the separation of solids from the liquid while storing the accumulated solids•The seepage pit allows the effluent from the septic

tank to infiltrate into the soil•The seepage pit is constructed similarly to a

cesspool

EldredgeSeptic.com

Septic Tank - Soil Absorption Systems

•The septic tank is a watertight chamber constructed of concrete•One of the most important components of the

septic tank is the baffle•The inlet baffle forces the wastewater from the

building sewer line down into the tank•The outlet baffle prevents the scum layer from

moving into the soil absorption area

EldredgeSeptic.com

Septic Tank-Soil Absorption Systems

•Septic tanks have an inspection port for checking the condition of the inlet baffle•Septic tanks also have a manhole access port for

cleaning the tank•Older homes may need access risers placed on the

tanks to bring the manhole opening closer to grade to allow for proper maintenance

EldredgeSeptic.com

Typical Septic System

EldredgeSeptic.com

In-Ground Soil Absorption Areas

• The soil absorption area receives the liquid effluent from the septic tanks and distributes it over a specific area• The effluent then filters through the soil under the pipes and is

treated chemically and bacterially by the components of the soil• The size of the soil absorption area is based on the size of the

house and the percolation rate of the soil• State law requires that there be at least four feet of usable soil

for the effluent to percolate through before it reaches the water table

EldredgeSeptic.com

Types of Conventional Soil Absorption Areas

•The soil absorption area may be:• An inground seepage bed• A set of trenches• An elevated sand mound

The type of system installed will depend on the slope of the property, the depth of usable soil, and the percolation rate

EldredgeSeptic.com

In-Ground Seepage Bed

• For seepage beds, the entire absorption area is excavated and lined with crushed stone• The pipes (laterals) are then placed over the stone and the

entire bed area serves as an absorption area for the effluent• Leaching chambers may be used in place of gravel

EldredgeSeptic.com

Inground Trenches

• A standard trench absorption area consists of two or more excavated trenches in which perforated pipes or laterals distribute effluent into a layer of crushed stone under the pipes• The effluent is then absorbed into the soil where it is

renovated

EldredgeSeptic.com

Gravity Distribution of Effluent

• Equal distribution of the effluent is very important to the proper functioning of the system•Most trenches and in-ground bed systems utilize gravity

distribution to the absorption from the septic tanks• In all trench systems a distribution box is used to split the

flow equally to the individual laterals in the absorption area. It is important that this box remain level.• In most bed systems, a piping loop is used instead of a

distribution box

EldredgeSeptic.com

Pressure Dosed Systems

• Some systems may require pressure distribution due to the permeability characteristics of the soil• In this type of system, the effluent from the septic tanks

flows by gravity into a dosing tank• The dosing tank forces effluent through the distribution lines

in a controlled dose so that all pipes discharge effluent at the same rate throughout the absorption area• The pressure distribution system has two distinct

advantages• The entire length of the lateral is utilized• The soil absorption area is allowed to rest between doses

EldredgeSeptic.com

Elevated Sand Mounds

• The elevated sand mound system is used in areas with reduced permeability, shallow soils, and poor drainage characteristics• Soils in these areas require the addition of sand above the ground to

provide for adequate renovation of the sewage prior to reaching the water table• The absorption area is constructed similarly to a standard seepage bed

or trench, except that the system is required to use pressure distribution and a layer of sand must be placed between the crushed stone and the natural soil cover• A soil berm is placed around the mound to protect it and to provide a

suitable base for the establishment of a vegetative cover• The mound is preceded by a dosing tank which must be equipped with

an audible and visual alarm system to alert the homeowner when a pump failure occurs

EldredgeSeptic.com

Elevated Sand Mound

EldredgeSeptic.com

Aerobic Treatment Tanks

• An alternative to the septic tank is an aerobic treatment tank

• These systems utilize an air compressor or a churning propeller to maintain an aerobic environment for the growth of aerobic microorganisms

• These microorganisms break down the sewage like the anaerobic bacteria found in the septic tank

• Proper functioning of this type of treatment tank is highly dependent upon the diligent maintenance of the mechanical components of the aerobic system

EldredgeSeptic.com

Have Questions?

Need Help?

Let us know how we can help you!

www.eldredgeseptic.com