Commercial and Residential Septic Installation
There are different types of Septic systems. Homeowners are not free to choose from all types due to local codes not allowing certain systems to be installed where Soil absorption or drainfield space is limited. In addition, each has its own advantages and disadvantages. Most localities require a soil scientist to perform a site/soil evaluation. The results of soil evaluation determines the homeowners options. Septic System Installation (Residential and Commercial) costs also vary by type, so there is much to consider when choosing the system that's best for you. For more information on what type of system is appropriate for you, contact you local health department:
Iredell County Environmental Health Department
Alexander County Environmental Health Department
Cabarrus County Environmental Health Department
Catawba County Environmental Health Department
Mecklenburg County Environmental Health Department
Rowan County Environmental Health Department
Wilkes County Environmental Health Department
It is important to understand your particular type of system and how to care for it. The following is a brief explanation of the most common types of septic systems.
The most common types of septic systems are:
Conventional Gravity SystemsPressure Distribution System (Pump System)
1. Conventional Gravity Systems
The most common type of septic system is a
Conventional Gravity System
As the name implies, gravity drainfields work by letting gravity drain the effluent from the septic Tank into a series of trenches. This means that a gravity drainfield area must be below the draining level of the septic tank. If this is not the case then another type of system must be used.
A TYPICAL CONVENTIONAL GRAVITY SYSTEM HAS THREE PARTS:
1. Septic Tank
A septic tank is watertight container and about 9 feet long and 5 feet tall. It is buried in the ground just outside the home. The tank is generally precast from reinforced concrete. Tanks are also made from plastic and fiberglass. A tank size is determined by the number of bedrooms in a home. The most common tank size used in North Carolina in the past several years is 1000-gallon liquid capacity. Today, the design of the tank includes two chambers each equipped with a manhole cover for tank access.
Wastewater from the home flows into the septic tank., including shower, bathtub, and washing machine. As the wastewater flows into the tank, the heavy solid materials settle to the bottom of the tank (forming a sludge layer), and the lighter greases, fats and oils float to the top (forming a scum layer). The septic tank’s primary purpose is to retain the solids. A properly working septic tank is full of wastewater. For every gallon of water that enters the tank from the home, a gallon of water is pushed out of the tank through the outlet baffle and enters the drainfield. Solids remain in the septic tank and gradually build up over time. If not removed by regular pumping, solids can overflow out of the tank and into the drainfield where they clog the soil and cause the septic system to fail. The outlet baffle (or a sanitary tee at the outlet end) prevents sludge and scum from flowing out with the liquids and entering the drainfield. Septic systems installed since 1999,include an effluent filter in the septic tank. These are installed in place of the sanitary tee at the outlet end of the septic tank.
The drainfield delivers the liquid sewage(effluent) to the soil. The real treatment of the wastewater happens in the soil underneath the drainfield. Liquid sewage (effluent) flows out of the tank as a cloudy liquid that still contains many disease-causing germs and pollutants. In a conventional gravity system, the drainfield is made up of a network of perforated pipes laid in gravel filled trenches (2-3 feet wide) or beds (up to 10 feet wide) in the soil. Wastewater trickles out of the pipes, through the gravel layer, and into the soil for final treatment. The size and type of drainfield depends on the estimated daily wastewater flow from the home and soil conditions. Every new drainfield is required to have a designated replacement area. It must be maintained as a reserve in case the existing drainfield ever needs to be replaced.
The most common types of drainfields are described below.
Gravel System and Gravelless System.
Gravel System- A gravelled system uses gravel/crushed stone in the drainfield trenches to create void space to store the effluent and release it slowly. This type of conventional septic system functions using drainage. During construction, a ditch 1 to 3 feet below ground level is constructed. The length is determined by the anticipated flow of effulent (wastewater) into the system from the home or business, as well as the soil's ability to absorb water. Gravel is placed in the bottom of the ditch.A perforated pipe (pipe with holes) is placed in the ditch. Gravel is poured over and around a perforated plastic pipe. The pipe is then topped with a covering to keep the soil from sifting through the gravel. Finally, a layer of soil is placed on top. The waste from the septic tank is then slowly diffused into the soil away from the home or business over time. While some treatment of waste occurs in the septic tanks as bacteria within the tank operate on the waste, most of the treatment occurs as wastewater from the tank enters the drainfield and is filtered through the gravel and the soil below. Over time, bacteria and other organisms, in the soil, consume material in the wastewater. These organisms multiply and form a layer called a biomat that sits on the soil layer. When sufficient oxygen is available, worms and other parasites feed on the bacteria as well as the material in the wastewater. When the drainfield is in balance, these organisms keep the biomat from becoming so thick that it won't allow passage of wastewater to the soil below.
25 % Reduction System
Polystyrene-EZflow by Infiltratoris an environmentally friendly replacement to traditional stone and pipe drainfields using an engineered geosynthetic aggregate modular design. The EZflow system is designed to improve drainfield performance by eliminating the fines, and reducing compaction and embedment associated with stone. Preassembled units include a 3" or 4" perforated pipe surrounded by aggregate and held in place with durable, high-strength netting.
Chambers-Infiltrator® chambersare hollow structures that attach end-to-end. They are installed in trenches or beds without gravel (except where local codes require the use of gravel). The entire bottom of the trench is open for unobstructed infiltration of water. The large storage volume within the hollow chambers accommodates peak flows of effluent from the home. Infiltrator chambers also feature patented sidewall louvers that allow lateral leaching of effluent into the soil. Can be installed in tight, sloped and curved areas creating less site disruption
50 % Reduction System
T&J Panel System
-The Panel System began primarily because of insufficient space for conventional systems. The T & J Panel offers a 50% reduction on total line lengths in the state of North Carolina. The Panel System should be considered when: a quality effluent may be needed, space is limited, usable soil is limited, or some future time space may be needed for other development. The Panel System can be installed as either gravity, pump to gravity, pump to pressure manifold, or low pressure pipe distribution. The biggest difference between the Panel and other systems is the area needed and the quality of effluent being introduced into the ground
The soil below the drainfield provides treatment and disposal of the wastewater. After water passes into the soil, most of it percolates through the soil, eventually entering the groundwater. Local groundwater is the source of drinking water for the majority of people in rural areas, such as ours. A small amount of wastewater is taken up by plants through their roots, or it may evaporate from the soil. Most of the wastewater filters through the soil in small open spaces, called soil pores. Chemical and biological processes in the soil treat the wastewater before it reaches groundwater, or a restrictive layer, such as hardpan or bedrock. These processes work best where the soil is somewhat dry, absorbent, with plenty of oxygen for at least 3 feet below the drainfield.
Another type of septic system is a Pressure Distribution System (Low pressure Dose System)
2. Pressure Distribution System
A TYPICAL PRESSURE DISTRIBUTION SYSTEM HAS THREE PARTS:
1. Septic tank
2. Pump tank and pump.
Septic tanks and drainfields have been used for many years but not all sites allow for gravity septic systems. A pump tank allows the drainfield to be located upslope from the septic tank. The drainfield is dosed which permits intermittent resting of the drainfield between dosing.
A pump tank is a concrete, fiberglass, or plastic container that collects the waste water from the septic tank. It contains:
(2) pump control floats
(3) high-water alarm float
(4) pump discharge pipe
(5) union and valve
(6) nylon rope
The (1) pump can be controlled either by the use of control floats or by timer controls. (2) Control floats turn the pump “ON” and “OFF” to pump a specific amount of wastewater. Timer controls are set to control the amount of the wastewater and the rest period between doses. The (3) high water alarm float starts an alarm to warn of pump malfunction. The alarm can also warn you of too much water use in the home. The float is set to start when the wastewater in the pump chamber rises above the “ON” float. The alarm should have a buzzer and an easily visible light. It should be on an electrical circuit separate from the pump. The (4) pump discharge pipe should have a (5) union and valve for easy removal of the pump. A piece of (6) nylon rope should be attached to the pump for lifting the pump in and out of the chamber.
Pressure Distribution Systems can be "pump to gravity" , "pump to pressure manifold" or "low pressure pipe distribution"
All conventional systems have biomat in the drainfield which forms in the upper 1 to 6 inches of the soil at the soil/trench interface just below the trench bottom. This biomat zone is useful. It remove many of the germs and chemical pollutants. If solids accumulating in the septic tank are not pumped out, they can flow into the trenches and accumulate into an intensive biomat that becomes too thick. This causes the biomat to clog the soil and does not allow the sewage effluent to flow out of the trench. An improperly maintained system will fail and cause untreated sewage to completely fill the trenches and come out on top of the ground or back up into the home in its plumbing system.
Other non-conventional systems include drip systems and other alternative type systems. Call for more information on these systems.
Lentz Wastewater is licensed for various septic system installation types for commercial and residential customers