| Traditional drainage checks | Evidence | Frequency |
|---|---|---|
Verification of pipe material |
Ticket |
All sources |
Verification of precast concrete units |
Ticket |
All sources |
Verification of surface water covers & frames |
Ticket |
All sources |
Verification of bedding material |
Ticket |
All sources |
Verification of backing material |
Ticket |
All sources |
Inspection of pipe bedding |
Ticket |
All lengths |
Inspection of line and level of laid pipes |
Ticket |
All lengths |
Inspection of backfill (Type 1/Type 3) and compaction |
Ticket |
All lengths |
Verification of protection method of any pipework |
Ticket |
All lengths |
Check dimensions of any highway drain |
Ticket |
All lengths |
Air tests on pipelines |
Testing |
Each length between chambers |
CCTV survey by certified company of all highway drain pipes including gully laterals |
Report |
All lengths |
| Sustainable drainage checks | Evidence | Frequency |
|---|---|---|
Verification of type B sub-base material |
Ticket |
All sources |
Verification of geotextile |
Ticket |
All sources |
Verification of grass seed & turf species |
Ticket |
All sources |
Confirm air voids ratio for sub-base -permeable paving |
Visual |
One sample |
Check SuDS dimensions / profile on site |
Visual |
All lengths |
Check correct erosion & scour protection on outlet pipes |
Visual |
As required |
Check top soil depth |
Visual |
All lengths |
Confirm check dam locations |
Visual |
As required |
Check sub-base depth |
Visual |
All lengths |
Laying and lapping of geotextile – ensuring overhang runs up the back of the back of the kerb race |
Visual |
All lengths |
Groundwater levels are in accordance with the approved design |
Visual |
As required |
