A septic tank is an underground chamber, typically made of concrete, fiberglass, or plastic, that plays a crucial role in waste management for properties not connected to public sewers. It essentially acts as a mini wastewater treatment plant on your own land. Here’s a breakdown of its function:

Function:

• Waste collection: It receives wastewater from your home, including toilets, sinks, and showers.
• Separation: Inside the tank, the wastewater separates into three layers:

• Scum: Oils and grease float to the top.
• Effluent: Partially treated liquid (water) remains in the middle.
• Sludge: Heavier solids settle at the bottom.

• Partial treatment: Anaerobic bacteria (those that thrive without oxygen) decompose the sludge, breaking down organic matter.
• Effluent disposal: The clarified effluent flows out of the tank and typically goes to a drainfield for further filtration and treatment by the soil.
• Sludge management: The remaining sludge needs periodic pumping and proper disposal to maintain the tank’s efficiency.

Benefits:

• Provides basic wastewater treatment where public sewers are unavailable.
• Relatively simple and cost-effective compared to other on-site systems.
• Low maintenance with proper care and pumping.

Important things to note:

• Septic tanks require regular maintenance, including pumping the sludge every 1-2 years.
• Using harsh chemicals can harm the beneficial bacteria in the tank.
• Overloading the system with excessive water or improper waste disposal can cause malfunctions.

How Septic Tank Works

The influent enters the tank and goes through the three main stages of treatment:

Stage One : Separation of Liquids and Solids The influent enters the first compartment of the tank where solid waste settles at the bottom and the clear liquid flows on top.

Stage Two : Anaerobic Decomposition In the absence of oxygen decomposing microbes (called anaerobic bacteria ) break down the solid material further.

Stage Three : Clarification The partially treated liquid flows into the second compartment where it further settles and clarifies.

The treated liquid known as effluent flows out of the tank and eventually goes to the drainfield for further filtration and treatment. The sludge remains at the bottom of the tank and needs to be pumped out periodically for disposal. It is important to note that septic tanks are not fail -proof and regular maintenance is important for their effective functioning.

Additional tips on how to maintain your septic tank:

• Do not put chemicals down your drains that could harm the microbes living in the septic tank.
• Do not overload the system by flushing down extra water or putting strain on the toilet.
• Plant vegetation over the drainfield but be careful not to let deep -rooted vegetation like black locust or poplar trress grow there as they can ruin the drainfield.

Septic Tank Construction Principles

The construction of a septic tank involves several steps to ensure its proper functionality and durability. Here’s a general overview of how a septic tank is constructed:

1. Site Evaluation:
   • Before construction begins, a site evaluation is conducted to assess soil conditions, groundwater levels, and other factors that may affect the performance of the septic system.
2. Permitting and Design:
   • Obtain necessary permits from local authorities and health departments.
   • Develop a detailed design plan that considers the number of bedrooms or occupants, soil conditions, and local regulations.
3. Excavation:
   • Excavate a hole in the ground for the septic tank installation. The size and depth of the hole depend on the tank’s dimensions and the local requirements.
4. Installation of the Tank:
   • Lower the septic tank into the excavated hole, ensuring that it is level and properly aligned.
   • Tanks are typically made of concrete, fiberglass, or plastic. The choice of material depends on factors like local regulations and the soil conditions in the area.
5. Inlet and Outlet Installation:
   • Install the inlet and outlet pipes. The inlet pipe carries wastewater from the building to the septic tank, while the outlet pipe allows effluent to flow from the tank to the drain field.
6. Baffles and Dividers:
   • Inside the tank, baffles and dividers are often installed to help control the flow of wastewater and prevent the disturbance of settled solids. These components ensure that only the liquid portion (effluent) moves to the drain field.
7. Backfilling:
   • Once the tank is properly positioned and the pipes are installed, backfill the space around the tank with soil to secure it in place.
8. Vent Installation:
   • Install a vent pipe on the septic tank to allow gases, produced during the anaerobic digestion process, to escape safely. This helps prevent the buildup of pressure within the tank.
9. Final Inspection:
   • After construction, the septic tank system is inspected to ensure compliance with local codes and regulations.

How Concrete Septic Tank is Constructed

Constructing a concrete septic tank involves meticulous planning and execution to ensure its structural integrity and proper functioning. Here’s a breakdown of the process:

1. Planning and Permitting:

• Size and Location: Determine the tank size based on local regulations and the number of residents. Choose a location away from wells, buildings, and property lines.
• Permits: Obtain necessary permits from local authorities before starting construction.

2. Excavation and Preparation:

• Excavation: Dig a pit exceeding the tank’s dimensions to accommodate formwork and gravel bedding.
• Gravel Bedding: Lay a 4-6 inch gravel bed to provide drainage and prevent settling.

3. Formwork and Reinforcement:

• Formwork: Build sturdy wooden or metal forms around the excavation, matching the desired tank shape and size.
• Reinforcement: Install a steel rebar mesh throughout the formwork for structural strength and stability.

4. Concrete Pouring and Curing:

• Concrete Mix: Use a high-quality concrete mix suitable for underground structures and resistant to water pressure.
• Pouring: Carefully pour the concrete mix into the formwork, ensuring proper compaction and eliminating air pockets.
• Curing: Allow the concrete to cure undisturbed for several days, following the manufacturer’s recommendations.

5. Installation and Finishing:

• Pipes and Baffles: Install inlet, outlet, and vent pipes according to the planned layout. Consider baffles in larger tanks to optimize separation and treatment.
• Access Hatch: Install a watertight access hatch on top for inspection and maintenance.
• Backfilling: Carefully backfill the excavation with soil, compacting it to prevent settling and ensure proper drainage.

Additional Considerations:

• Waterproofing: Apply a waterproofing membrane to the exterior of the tank for enhanced protection against moisture and corrosion.
• Compaction Testing: Consider soil compaction testing to ensure the surrounding earth can adequately support the tank’s weight.
• Professional Installation: While DIY construction is possible, consulting and potentially hiring experienced professionals for critical steps like pouring and waterproofing is recommended for optimal results and adherence to local regulations.

How Septic Tank can be Constructed with Sandcrete Blocks

Constructing a septic tank using sandcrete blocks requires careful planning and execution to ensure its structural integrity and safe operation. While it can be a DIY project, consulting a qualified engineer or licensed contractor is highly recommended due to the critical nature of proper wastewater treatment and potential safety hazards. Here’s a general overview of the process, remembering that local regulations and specific requirements may vary:

1. Planning and Permitting:

• Size and Location: Determine the tank size based on local regulations and the number of residents. Choose a location at least 50 feet away from wells, buildings, and property lines.
• Permits: Obtain necessary permits from local authorities before starting construction.

2. Excavation and Preparation:

• Excavation: Dig a pit exceeding the tank’s dimensions by at least 12 inches on all sides to accommodate block laying and backfilling. Ensure the pit depth meets local regulations.
• Gravel Bedding: Lay a 4-6 inch layer of crushed gravel or coarse sand over the bottom of the pit to provide drainage and prevent settling.

3. Block Laying and Reinforcement:

• Foundation Course: Lay a course of solid concrete blocks on the gravel bed, ensuring level and stable alignment.
• Block Walls: Start building the walls using sandcrete blocks, laying them in a running bond pattern (each block overlaps the one below it) with mortared joints.
• Reinforcement: Insert vertical steel rebar rods every few courses for added stability, especially in corners and around openings.
• Compaction and Backfilling: Regularly tamp down the backfill soil around the rising block walls to provide proper support and prevent voids.

4. Installing Internal Components:

• Inlet and Outlet Pipes: Install sewage inlet and effluent outlet pipes according to the planned layout, ensuring proper slope and tight connections.
• Baffles (Optional): Consider installing baffles in larger tanks to optimize separation and treatment of wastewater.
• Access Hatch: Install a watertight access hatch on top for future inspection and maintenance.

5. Sealing and Waterproofing:

• Internal Coating: Apply a waterproof sealant to the inner walls of the tank to prevent leaks and protect against corrosion.
• External Waterproofing: Consider applying a waterproofing membrane to the exterior of the tank for enhanced protection against moisture and groundwater.

Safety Considerations:

• Always prioritize safety when working with excavation and construction.
• Wear proper safety gear, including gloves, goggles, and sturdy shoes.
• Be aware of potential hazards like cave-ins and falling debris.
• Seek professional help for tasks beyond your skill level or comfort zone.
• Remember, improper septic tank construction can lead to serious health and environmental risks.

Remember, this is a general overview, and specific details may vary depending on your location and regulations. Consulting a qualified professional is crucial to ensure a safe and compliant septic tank system for your property.

Sizes of Septic Tank

The size of a septic tank is typically determined by the number of bedrooms in a household or the expected volume of wastewater generated. The size is commonly measured in terms of the tank’s capacity, which is expressed in either gallons or liters. The specific requirements can vary based on local regulations and building codes. Here’s a general guideline for septic tank sizes in terms of capacity:

1. Residential Use:
   • For a one to two-bedroom house: A septic tank with a capacity of 750 to 1,000 gallons (approximately 2,839 to 3,785 liters).
   • For a three-bedroom house: A septic tank with a capacity of 1,000 to 1,200 gallons (approximately 3,785 to 4,542 liters).
   • For larger homes, the tank size may need to be increased based on local regulations and the estimated wastewater flow.
2. Commercial Use:
   • For commercial or industrial applications, the septic tank size will depend on factors such as the number of occupants, the type of business, and the estimated volume of wastewater generated.

It’s important to note that these are general guidelines, and specific requirements may vary based on factors such as local regulations, soil conditions, and the type of septic system being used. Consulting with a local septic system professional or health department is recommended to determine the appropriate septic tank size for a specific situation.

Additionally, the dimensions of septic tanks can vary depending on their shape (rectangular, cylindrical, etc.), and these dimensions can be specified in terms of length, width, and depth. The actual dimensions may vary among manufacturers and regional standards. Always check local building codes and regulations for the most accurate and up-to-date information.