What we expect under the spadeGround
This office sits on Station Road in Teynham, between the A2 and the fruit farms, and the ground changes over a short distance here.
South of the A2 the higher land is chalk, usually under a cover of brickearth: a fine, pale, silty loam that stands up well in a dry trench and runs as soon as it is wet.
In a dry trench Brickearth will hold a face long enough to flatter the first hole of the week and drop it after rain.
North of the road the land falls to Milton Creek and the Swale, and the cover becomes alluvium and made ground: soft, wet, variable, and often holding whatever was tipped in it.
Made ground Variable within one trench, so the support is set for the worst length rather than the length at the shaft.
None of that is a survey result; it is what the trial hole is for. A hole is dug before a price is fixed on anything deeper than a shallow repair, and it settles the trench support, the bedding class, the need for dewatering and whether a soakaway is viable at all.
What the hole settles Material at each depth, whether water comes in and where it stands, and what is already buried. The third changes prices: a trench crossing two unrecorded services is a hand-dig.
Water: the aquifer and the tideWater
Chalk under thin cover is an aquifer, and what goes into the ground here can reach it. That rules out some kinds of discharge outright and makes others conditional, and it is settled with the regulator before a soakaway or an outfall is designed — not after it is dug.
The other water is tidal. The Swale and Milton Creek rise and fall, and anything discharging toward them has a window rather than a free run: an outfall that works at low water can be shut by the tide at high water, and a system relying on it has to hold what arrives in between. A gravity outfall near the marsh is designed around that, with a flap or a penstock and storage upstream of it.
Who has to agree to whatConsents
Four different bodies have a say on drainage work around here, and which one you need depends on what the pipe is and where the hole is. Mixing them up costs weeks.
-
Undertaker
Southern Water
Anything connecting to a public sewer, built over one, or offered for adoption.
-
Highway · LLFA
Kent County Council
Openings in the carriageway or footway, and the surface water strategy on a larger site.
-
Planning · BC
Swale Borough Council
Building control for most work here, and the drainage conditions on a planning permission.
-
Environment
Environment Agency
Where a discharge goes to a watercourse, or where the chalk groundwater is at stake.
A build-over or build-near enquiry is worth starting earlier than feels necessary. Finding out that an extension sits over a public sewer is cheaper on a drawing than in a trench, and the survey that proves where the sewer runs is the same survey that would have been done anyway.
Getting plant to the holeAccess
Access here is mostly about width and timing. The A2 runs through Teynham with frontages tight to it, Station Road is narrow and parked, and the London-to-Ramsgate line crosses between Sittingbourne and Faversham with level crossings that will not take a slow or heavy load without arrangement. Any of those turns a half-day dig into a job with signing, a permit and a working window.
South of the road the problem reverses: there is plenty of room and no hard surface, but getting to it means a farm track, a headland between rows and a gate somebody has the key to. Those are agreed with whoever farms the land before a machine moves, along with where spoil can be put and when the track can be used.
Occupied buildings add their own timing. Taking a foul run out of use to patch it means the building has no drainage while the resin cures, so the work is set against whatever hours suit the occupier, and the chamber is left safe and covered in between.