What we surveyed
A CCTV inspection at a residential property in Solihull, covering 3 separate runs of pipework, 100 and 150 mm bore, foul and surface water.
The system is vitrified clay.
Vitrified clay is what most pre-1970s drainage in the Midlands is built from. It is durable but brittle, and its short pipe lengths mean many joints – which is where almost everything goes wrong.
What the camera found
17 defects were logged and coded.
The worst section graded C on the Drain Repair Book scale.
Displaced and open joints (14 observations)
Displaced joints are where one pipe length has moved relative to the next. Ground movement and, across much of the Black Country, historic mining subsidence are the usual causes. Each step is somewhere solids can lodge and roots can enter.
| Distance | Code | Observation |
|---|---|---|
| 0.20 m | JDM | Joint displaced medium |
| 0.50 m | JDL | Joint displaced large |
| 0.90 m | JDM | Joint displaced medium |
| 1.30 m | JDL | Joint displaced large |
| 1.70 m | JDM | Joint displaced medium |
| 1.90 m | JDM | Joint displaced medium |
_Distances are measured from the start of the run in which each observation was recorded, not from a single point._
_8 further displaced and open joints observations were recorded._
Cracking and fracturing (3 observations)
A crack is the stage before a fracture, and a fracture is the stage before a collapse. Catching one on camera is the difference between a patch liner and an excavation.
| Distance | Code | Observation |
|---|---|---|
| 0.50 m | CC | Crack, circumferential 07-03 |
| 0.90 m | CL | Crack, longitudinal 11 |
| 5.70 m | CC | Crack, circumferential 03 |
_Distances are measured from the start of the run in which each observation was recorded, not from a single point._
Outcome
CCTV drain surveys in Solihull
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