What is a Seepage Pit? What You Need to Know
When exploring septic system solutions, homeowners often come across terms like “leach lines” and “seepage pits.” While leach lines are more commonly discussed, seepage pits are another vital part of the conversation. Let’s explore what they are and when they’re used over traditional leach lines and the importance of understanding that seepage pits require a different soil testing procedure than traditional leach lines or chamber systems.
What is a Seepage Pit?
A seepage pit is a deep, vertically oriented excavation in the ground that receives effluent or partially treated wastewater from a septic tank. Its purpose is to allow this effluent to seep or percolate into the surrounding soil gradually.
The seepage pit or pits (the system flow may require there to be more than one) are connected to the outlet side of the septic tank with what is called a crossover sewer line. If there is more than one seepage pit, the crossover line will connect to a distribution box that will then connect to all of the pits servicing the system. The pits are required to have a 12’ separation, from edge to edge, from the other pits.
A large drill rig drills these pits, which measure between 4 and 6 feet in diameter and can reach depths of over 50 feet. After drilling, workers fill the hole with perforated sewer pipe and ¾ to 1½ inches of washed aggregate rock to ensure the smooth transfer of wastewater into the surrounding area.
When to Consider Seepage Pit Installation Over Traditional Leach Lines?
There are specific scenarios where a seepage pit might be more favorable than leach lines:
**Space Constraints:** Seepage pits have a smaller horizontal footprint, making them ideal for properties with limited space.
**Usable Property Space:** Unlike traditional leach lines or chamber systems, seepage pits allow for more property space to be used for other things, such as swimming pools, exquisitely landscaped yards, driveways, courtyards, etc.
Types of Seepage Pits
Types of Septic Seepage Pits
When it comes to managing excess water from septic systems, seepage pits offer a variety of solutions. Let’s explore the different types available:
1. Cylinder of Unmortared Blocks
This is a popular and convenient choice. It comprises hollow-core masonry blocks designed to let water efficiently pass through. While these blocks are typical, you can use solid blocks or bricks if you leave space between them to allow for proper drainage. Professionals usually cover the structure with a heavy-duty precast concrete slab because of its substantial weight.
2. Stone-Filled Dry Well
For a minimalist approach, a stone-filled dry well is the simplest option. This structure consists of a pit filled with rocks of various sizes. It effectively manages small volumes of clean water, such as runoff from an outdoor shower or pool overflow. However, it has limited capacity and isn’t suitable for handling larger water waste volumes, like those from laundry machines.
3. Drum of Precast Concrete Rings
These seepage pits use sturdy ring liners that interlock, forming a robust and long-lasting structure. Available in 4 to 8-foot diameters, they facilitate outflow while preventing debris infiltration. Their significant weight means they typically require professional installation unless you have the necessary equipment and manpower.
Each type of seepage pit offers unique advantages depending on the specific water management needs and installation circumstances.
Installation Process
Site Evaluation: First, an assessment of the site’s suitability for a seepage pit is carried out. This includes evaluating the soil type, water table levels, and available space. Sandy soil, known for its clod-like structure that crumbles easily, is often the best for drainage. Its natural ability to allow water to pass through makes it ideal for seepage pits.
In contrast, soil that is dense, hard, dry, dull gray, or mottled is usually nonabsorbent. Such soil types can hinder the effectiveness of a seepage pit, as they do not facilitate proper water absorption and drainage. To ensure optimal conditions, inspect the soil by turning up shovelfuls at several locations in your yard. Identify areas with the most suitable characteristics before proceeding.
Seepage Performance Testing: This crucial test determines the soil’s capacity to absorb and treat the effluent. It’s a specialized soil test that’s imperative for a successful installation. By digging a test hole and experimenting, you can gather vital information about the soil’s absorbency, ensuring that the seepage pit will function as intended. To learn more about this entire process you can read about it here. The hole will be filled back in after testing.
It’s crucial to complete this process correctly and to obtain a permit from the County before installation. The County thoroughly checks various factors to protect our environment and ensure groundwater quality. There is a great article from the EPS in April 2001 that explains why these illegal seepage pits can be catastrophic if not engineered and designed properly
Digging: After completing the tests, excavation begins. The depth and width of the pit depend on the amount of effluent expected and the soil’s absorption rate or you may hear us refer to it as the SAR. Our team will drill the seepage pit near the test hole, avoiding the exact same location
Constructing: Then, perforated sewer line and aggregate rock fill the pit to facilitate wastewater dispersion. Consider the soil type: sandy soil is ideal for drainage, while dense, hard, or dull gray soil is typically nonabsorbent.
Connecting to the Septic Tank: After constructing the pit, a crossover line or distribution box connects it to the septic tank for multiple seepage pits. This ensures efficient transfer of wastewater from the home to the seepage pit system.
How does it work?
Once the septic tank reaches its operating level, every flush pushes water, called effluent, out of the tank and into the seepage pit. There, the effluent filters into the ground, where the soil treats it before it reaches the water table. Pretty amazing, right? Mother Nature truly works wonders!
The seepage pit might not get much attention, but its importance is most certainly undeniable. Whether you’re considering installation or need expert guidance on seepage pit performance testing, trust the professionals at Priority Pumping. We’re here to ensure your septic solutions are efficient, safe, and tailored to your property’s needs.
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