Installing a Sewage Treatment Plant

In this video, our Marketing Coordinator Laura explains the process of installing a Marsh sewage treatment plant, conducted by Cotterill Contractors. This was part of a project within a new build property in Kenilworth.



What does the process involve?


The first stage of the process involves excavating a hole in the desired location, which is big enough for the tank, plus an extra 200mm either side. This is to make sure the tank can be emptied with ease. The tank is then lowered into the hole, with a small amount of concrete to secure it. Next, water is pumped into the tank to stabilise it, while the next step is completed. The area surrounding the tank is backfilled with concrete to make sure it is fully secure. Once this step is complete, the inlets and outlets need to be connected, with the outlet leading to a soakaway field. The sewage treatment plant treats the wastewater, so that it is clean enough to be drained back into the ground. Lastly, the tank is connected to the electrics, and is commissioned. Once this is complete, the tank is ready for use.


Marsh sewage treatment plants work by using a three stage system to treat the effluent which are as follows: initial settlement, chemical treatment, final settlement.
1. The effluent enters the initial settlement chamber, where the solids sink to the bottom to form a sludge which is expertly removed by a tanker.
2. The remaining liquid moves forward to the chemical treatment zone. In this biozone, air containing oxygen is added to the liquid to stimulate the growth of aerobic bacteria (found naturally in the sewage) by allowing them to breathe. Most treatment plants provide a large surface area for the same bacteria to grow upon and grip to.
3. Lastly, the treated effluent moves into the final settlement chamber where the stillness allows biological material to settle at the bottom for removal or further treatment. The remaining settled liquid then flows out to surface waters or soakaway field.


Servicing and emptying
We recommend getting your sewage treatment plant serviced and emptied once a year if it’s on a domestic property. If it is on a commercial property, we recommend getting it emptied every 3-6 months.