How is a Septic Tank Constructed?
Understanding Septic Tank Construction
A septic tank is constructed as a watertight underground container, often made from concrete, plastic, or fiberglass. Its purpose is to separate and process household wastewater through settling and bacterial decomposition. The process begins with careful site preparation and involves precise engineering to ensure compliance with building codes and avoid leaks or contamination.
Key Steps in Constructing a Septic Tank
1. Site Assessment and Preparation
Before constructing a septic tank, it’s crucial to select a site away from buildings, wells, and large trees to prevent future complications. The ground needs to be excavated to accommodate the tank, typically about 1.5–1.8 meters deep, and leveled to provide a stable base. If the ground comprises sandy soil, laying a gravel bed is advisable for added stability.
2. Forming the Tank Base
The base of the tank is usually formed with a concrete slab, reinforced with a steel grid to prevent cracking. This foundation helps in supporting the structure and resisting ground pressure. The concrete should be allowed to cure for at least 24 hours before proceeding to the next phase.
3. Wall Construction
Most often, walls are constructed using concrete blocks or poured concrete, both reinforced with steel for added strength. These materials provide the necessary durability and watertightness. Walls are typically around 230 mm thick, ensuring structural stability. The bond between the walls and the tank base is reinforced using rebar.
4. Internal Structure and Chambers
Septic tanks usually have two chambers, separated by baffles that manage flow and promote sedimentation. Internal piping is installed to allow for efficient inflow and outflow of wastewater. These pipes must be resistant to acid and are generally constructed from PVC materials.
5. Tank Cover and Access Points
The cover of the septic tank, or lid, is often a concrete slab embedded with access ports. These ports facilitate future inspection and maintenance, which is crucial for the system’s longevity. Manholes with a diameter of 12 inches or more are standard for easy access.
6. Finishing Touches and Waterproofing
Applying a waterproof seal to the tank’s interior and exterior surfaces is essential to ensure watertight construction and prevent any leakage. Finally, the area around the tank is backfilled to secure it in place, and final plumbing connections are made to link the tank to the home and drainage field.
Materials and Design Considerations
Concrete and Steel Reinforcement: Favoured for their durability and strength in septic tank construction.
Fiberglass and Plastic: Lightweight alternatives that are quick to install but require careful handling to avoid damage.
Inspection Ports: Critical for ongoing maintenance and should be included in the tank design.
You Might Also Wonder...
What permits are required for septic tank installation? Check with your local authorities as regulations can vary significantly.
How often should a septic tank be pumped? Regular maintenance, including pumping every 3-5 years, is necessary for system health.
Are there environmental concerns with septic tanks? Yes, improper installation and maintenance can lead to groundwater contamination.
Key Things to Remember
Professional installation and design are key. Ensure compliance with local building codes and guidelines, and always hire experienced professionals to minimize the risk of environmental contamination. Regular inspections and maintenance will help prolong the longevity of the system and protect your investment and surroundings.
