Overview
Premier Water Solutions 10 Ltd was appointed as the principal contractor and designer under Construction Design and Management Regulations 2015 to obtain building regulations to provide a foul and surface water drainage solution which would be acceptable to the statutory authorities.
This involved:
- Removing an existing septic tank and drainage system that was antiquated and had failed, leaving the garden area boggy underfoot and unusable
- Undertaking percolation testing to reveal that there was no soakage at 1m or up to 2m below ground level
- Without an option for a traditional drainage field or a vertical type soakaway, a solution was proposed for a septic tank draining to a drainage mound, the first for Cornwall Council Building Control
- Installing surface water swales downslope of the drainage mound, should there be any seepage at the interface between the mound and the natural ground, with a large mound at the base of the field to ensure all effluent remained on site
Proposals
- New 100mm diameter foul water pipework to the front and rear of the house and removing existing macerator pump from downstairs toilet
- Installing new surface water pipework around the house to the swales
- Installing a new septic tank
- Installing a new pump station with a fixed weather proof control panel
- Designing and building the first drainage mound for approval with Cornwall Council
- Decommissioning the old septic tank and re-landscaping the surrounding area
Conclusion:
The project went well and building control commented that the site was tidy and all the drainage runs were well marked with the correct gradient. The drainage mound was the particular star of the show, because there are only a few pockets in Cornwall where there is little drainage. Yet one year on, the drainage mound is fully functioning with little seepage around the base. We have been back to site only once to undertake the servicing of the pumps in the pump station and to supervise the de-sludge of the septic tank.