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Septic Tank Replacement Process

When septic tanks are working efficiently, they do not require much thought or effort. You will need to carry out annual checks and maintenance and the occasional improvement may be necessary. However, overall a septic system is a lot less worrisome than people believe. With this in mind, however, when a septic tank suffers from an advanced failure or damage, it can cause issues and a replacement will be necessary.

The Septic Tank Replacement Process

The Problem

  • A septic tank as opposed to a cesspool, which is a sealed tank, uses a baffle or dip pipe arrangement which effectively holds the solids in one section and allows the fluids to cross over the baffle. The effluent then requires to be filtered by a soakaway in the ground.
    The first sign of a failure is the septic tank “backing up” where the fluids cannot drain through to the soakaway.
    Common practice is to pump out this excess into a nearby ditch or watercourse as a point of discharge. However, this is a direct infringement of the rules governing sewage discharge governed by the Environment Agency.

The Soakaway

  • The septic tank will normally have a drainage field commonly known as a soakaway attached to enable the fluids to soak into the ground.
    When it fails it usually means it can no longer soak away. This causes the raw sewage to rise to the surface and can endanger public health.

Survey & Report

  • The next step is a survey. This involves having the tank pumped to establish its condition. A CCTV camera survey follows to clarify the condition of the drainage network.

Percolation Test

  • Any form of septic tank or soakaway replacement will require a Percolation Test. This assesses the absorption qualities of the soil in the garden where the replacement will be sited. It is a Building Regulations statutory obligation and calculates the minimum size of the new septic soakaway or drainage field to safely store underground, the daily discharge from the property whilst it permeates into the ground.

The Solution

  • The Survey Report will highlight the extent of the problems confronting the householder. Each measure has a variable cost depending on size and scale of solution.

Extending Or Replacing The Soakaway

  • The least expensive measure is the replacement or extension of the existing septic soakaway. This is in the form of trenches in various widths containing perforated pipes surrounded in pea shingle, the extent of the network is defined by the Percolation Test calculation.

Retrofit Sewage Treatment Plant

  • In some cases, it is not possible to discharge flows to a new soakaway, perhaps due to lack of space, poor invert levels or the need to position in higher ground. In these instance’s a simple pump station will be included with the new soakaway. Alternatively, the most appropriate measure is a Retrofit Sewage Treatment Plant which can have a pump included. This is particularly beneficial where a watercourse can be accessed as rules dictate any discharge to a water course must be via a treatment plant.

Sewage Treatment Plant To Ground

  • In these two instances the original septic tank has to be operating effectively. If not the discharge will require treatment from a sewage treatment plant which conforms to national and European standards. The discharge from such a unit is virtually pure water and as such can be safely pumped or gravity fed to the ground via soakaway or drainage field as described above.

Sewage Treatment Plant To Watercourse

  • A domestic sewage treatment plant is the only ethical and environmentally acceptable method of replacing a septic tank. It is more expensive because it has multiple sections where the raw sewage is subjected to air injection from a compressor activating the sludge causing anaerobic digestion therefore purifying the fluids to the levels where it can be safely discharged into streams and rivers without harming marine life.