THE DRAINIST LTD — drainage surveys, repairs and new runs, Teynham

Reading a run from the downstream chamberMethod · in order

The order matters more than the kit: run it this way and the chainages can be found again.

Downstream cover first Chamber 01
A survey starts at the lower chamber, not the gully everyone points at: that cover shows whether the run already stands full.
Gas test, then levels Both ends
The chamber is gas-tested before anyone leans into it, and cover and invert levels are taken at both ends first.
In against the flow Upstream travel
The camera travels upstream, so chainage counts up from a cover already lifted and nothing is referenced to a point nobody can reach.
Code it where it is Clock reference
Chainage is read off the cable as it pays out, and each feature gets a clock reference — 12 the crown, 6 the invert — with a still.
Stop where the camera stops Reported, not assumed
Where the camera stops, the report stops: the length beyond an obstruction goes down as unsurveyed against the chainage reached, never as sound.

Defect grading scheduleGrades 1–5

Everything hangs off the five rows below. A coded feature gets a grade; the grade decides which remedies are on the table; the remedy decides who countersigns. Structural and service condition are graded separately on the same run.

Grading used on reports from this office
Gr.	Condition recorded on the run	Sheet
1	Barrel round, joints closed, full bore to the next chamber. Nothing coded.Structural 1 · service 1	Open
Evidence Still at each joint; nil-return chainage log; levels both ends. Remedy None. The run is recorded and dated. Signed off by The surveyor issuing it. A nil return needs no countersignature. Close
2	Hairline circumferential crack, slightly open joint, or deposits under five per cent of bore.CR · OJM · DES	Open
Evidence Still square on, chainage burnt in, clock reference, deposit depth against bore. Remedy Jet and re-survey the same visit: bore shown before and after. Signed off by Whoever commissioned it; the managing agent where one holds the building. Close
3	Multiple fractures, roots through a joint, deformation, or deposits five to twenty per cent of bore.FC · RI · D	Open
Evidence Stills at both ends of the defect length; deformation as a percentage of bore; chainage of the root joint. Remedy Cut roots, patch the joint. Fracturing along most of the run is lined end to end, not patched five times. Signed off by The owner, and the insurer’s surveyor while a claim is open. Close
4	Broken pipe with pieces displaced, invert missing, a hard obstruction the camera cannot pass, or running infiltration.B · OB · IN	Open
Evidence Last clear still; the chainage the crawl stopped at; water level in both chambers. Remedy Jet and re-survey first — an obstruction that moves was a grade 2. What remains is cut out or lined. Signed off by The undertaker on a public run; the street authority by permit in the highway. Close
5	Collapse. Bore lost, void over the crown, ground loss into the pipe, settlement at the surface.X · void confirmed	Open
Evidence Footage from each reachable end; the unsurveyed length as a figure; the surface recorded before lifting. Remedy Excavate and relay. Flow over-pumped, invert levels recovered, the void filled not bridged, the run tested before closing. Signed off by The undertaker’s engineer, the street authority for the opening, the owner for restored levels. Close

Note 1 · what the grade does not decideSched. note 1

A grade describes a length of pipe, not a job. The same code at the same grade is a two-hour patch under a driveway and a week of propping under a conservatory floor.

So the schedule is written before the quotation, with chainages, depth to invert and the surface above each defect.

Note 2 · fall, gradient and the slack runSched. note 2

A run that silts up every winter is usually not dirty. It is slack, and it was slack on the day it was laid.

Most settled deposits coded on a survey are a gradient fault: solids drop out of water that is not moving, and the bore narrows from the invert up.

Fall and gradient checker

Guide only

Measured on site Nominal bore Run length (m) Fall over that length (mm) Upper invert minus lower invert.

Enter a length and a fall.

Gradient: —
Reference gradient: —
Comparison: —

The reference is Maguire’s rule — one in the bore in millimetres over 2.5 — a rule of thumb and nothing more. What a run is built to comes from the designer and the current approval documents.

Note 3 · where surface water is putSched. note 3

Surface water is the other half of the schedule.

Plenty of foul runs around Teynham carry roof water they were never sized for, because a downpipe went into a gully that turned out to be foul.

Which gully is which A tracer at the head of the run, watched at the next chamber, settles it.

Taking the roof off means putting it somewhere else: a soakaway, a crate, or a surface-water connection agreed first.

Order of preference Ground first, watercourse second, sewer last, and the sewer only on written agreement.

Whether the ground will take it is a question about the ground, not the roof.

Before the sheet means anything A pit to the depth of the soakaway, filled and timed three times, slowest used.

Soakaway sizing sheet

Guide only

Trial figures · 15 minute storm Roof area drained (m²) Assumed rainfall (mm/h) Soil infiltration class Indicative until a soakage test gives a real rate.

Enter a roof area.

Inflow over the storm: —
Soaks away per metre run: —
Trench length needed: —
Storage to be held: —

Worked for one duration and one trench shape: a metre wide, a metre deep, open-chambered. A real sizing repeats this across several durations and takes the worst, on the rate measured in the pit.

Note 4 · work carried out under 42990SIC 42990

The registered activity is civil engineering not elsewhere classified; here that means buried drainage, in four kinds of work.

Record CCTV survey
A coded log against chainage, a still per feature, two grades. What a report must contain.
Remedy Patch, line or dig
Three remedies, and conditions on the run that take the choice away. Which a defect allows.
New work Laying a run
Set out upwards from the connection, bedded to a class, closed by test. Levels and bedding.
Submission Sewer adoption
Drawings, levels and calculations that have to agree. What goes in.

Survey requests go to the office email, with a street address and the cover positions if known. The ground is on the Sittingbourne page; what is kept afterwards is in what the office holds.

Note 5 · the hole, the plant and the reinstatementSched. note 5

Surface courseSaw-cut, squared

Binder courseJoint sealed to the cut

Sub-baseCompacted in layers

BackfillIn compacted layers

Granular surroundBedded and haunched

A reinstatement goes back in the layers it came out in, to the specification issued with the permit.

A drainage repair is mostly an excavation with a short piece of pipework in the middle. Utility records are pulled, the ground swept with a locator, trial holes dug by hand.

An opening in a public footway is a permitted street work with a reinstatement specification attached, not a patch of tarmac at the end of the day. One that fails inspection is dug up and done again at the opener's cost.

Soft ground is the same sequence in different materials, topsoil kept separate and put back last. How far the sides stand unsupported is a question about the ground around Sittingbourne.

Run A, logged end to end0–24 m

Chainage runs along the axis from the chamber the camera entered, so every figure is measured from a cover that was already open. The crawl stops at the obstruction at 18.40 m rather than running on, and the 5.6 m behind it stands surcharged and goes down as unsurveyed.