CCTV drain survey in Wolverhampton: cracking and fracturing

What we surveyed

A CCTV inspection at a residential property in Wolverhampton (WV4), covering 8 separate runs of pipework, 100 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

15 defects were logged and coded.

The worst section graded C on the Drain Repair Book scale.

Cracking and fracturing (6 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
0.00 m	CR	Crack, radiates from 03
4.30 m	CC	Crack, circumferential 12-04
5.90 m	CC	Crack, circumferential 02-06
7.60 m	CR	Crack, radiates from 02
9.50 m	CC	Crack, circumferential 11-04
10.60 m	CCJ	Crack, circumferential 07-09 at joint

_Distances are measured from the start of the run in which each observation was recorded, not from a single point._

Root ingress (3 observations)

Roots find their way in through the smallest opening in a joint, then thicken until they hold back everything moving past them. They are the most common single cause of repeat blockages in older clay drainage.

Distance	Code	Observation
0.70 m	R	Roots
7.20 m	R	Roots
8.30 m	R	Roots

_Distances are measured from the start of the run in which each observation was recorded, not from a single point._

Displaced and open joints (3 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
10.60 m	JDM	Joint displaced medium
11.10 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._

Defective lining (2 observations)

A defect in an existing lining means an earlier repair is no longer doing its job.

Distance	Code	Observation
0.10 m	LX	Lining defect
1.50 m	LX	Lining defect

_Distances are measured from the start of the run in which each observation was recorded, not from a single point._

Broken pipework

Broken pipework does not repair itself and will keep catching debris until it is dealt with.

Distance	Code	Observation
9.50 m	H	Hole in drain/sewer 12

Outcome

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CCTV drain surveys in Wolverhampton · Blocked drains in Wolverhampton