Septic Tank Replacement and Treatment System Upgrade in Oxted, Surrey

The Project

Alton Facility Services completed a septic tank replacement and treatment system upgrade in Oxted, Surrey. The works included excavating around the existing tank, installing a new non-electric treatment system, forming discharge drainage field pipework and reinstating the disturbed ground.

The Challenge

The site required an upgrade to the existing off-mains wastewater arrangement. The works involved opening up the existing tank area, removing sections of the old structure and preparing the system for a new non-electric treatment solution.

The team also needed to form a discharge drainage field down the bank, raise an existing manhole to ground level and provide future access with a new cover and frame.

The Solution

• Attended site with engineers and plant.
• Excavated around the grey water tank and removed the turret and tank lid.
• Removed vegetation from the solids handling chamber and fully emptied the chamber.
• Installed a new non-electric treatment system into the old tank area.
• Connected the two existing inlets into the new tank.
• Backfilled around the new tank and infilled the old solids handling tank with concrete.
• Excavated approximately 8 metres down the bank at around 450mm deep.
• Installed two lengths of perforated land drainage for the new discharge drainage field.
• Backfilled the land drain with geotextile membrane and 20mm stone.
• Raised the existing manhole to ground level and installed a new access cover and frame.
• Removed excess soil, reinstated disturbed surfaces and tested the system.

The Result

The new treatment system was installed, connected and left working. The discharge drainage field was formed and the access arrangements were improved for future servicing and maintenance.

The recommendation was for the new tank to be emptied twice yearly to help maintain performance and give the drainage field the best chance of working correctly.