Drain excavation means digging down to a failed pipe and replacing it. It is the method for pipes that have collapsed or lost their shape, which a liner cannot fix. It also suits long runs of badly worn pipe.
The engineer plans the dig from the camera footage, so only the damaged section opens. This limits the mess, because a precise dig is smaller than a guess. Pipe relining is the alternative when the pipe still holds its shape.
New pipe must meet the Building Regulations. Approved Document H is the government guide to drainage and waste disposal, and it covers pipe sizes and protection. The drain repairs guide explains how to compare the options.
The engineer reviews the survey, since the depth and length of damage set the dig. A clear scope of work should come before any digging. A written scope avoids arguments later.
A mini-digger suits open ground, while hand digging suits tight spots near walls. Shoring keeps a deep trench safe. Ask where the soil will go.
The engineer removes the failed length and lays new pipe to the correct fall. Joints to the old pipe need sealing well, since leaks start there. Ask which pipe material the engineer will use.
The trench is filled in layers so it does not settle. Ask whether the quote includes the surface, since paving and turf cost extra if they are left out. Ask who clears the site afterwards.
Use these questions to compare quotes, since the answers differ from one engineer to the next. Write the answers down, since a written note helps if the job changes. Then compare two quotes if the job looks large.
These are typical UK ranges from national guides, not Essex quotes. MyJobQuote lists excavation at £250 to £650 per metre and a partial replacement at £600 to £1,100. It puts a fully collapsed pipe needing partial or full replacement at £1,000 to £3,000. The average collapsed drain repair is about £850 on its list.
Ask for a written quote before work starts, because depth, length and surface repair all change the price. Compare it with a relining quote if the pipe allows both.
Usually, yes. A collapsed pipe cannot take a liner. A partly collapsed pipe may sometimes be relined. A camera survey shows which case you have.
A trench does disturb the surface. Ask the engineer how wide it will be, and whether the quote includes putting the surface back. Footage helps keep the dig small.
It depends on the job. Approved Document H covers drainage under the Building Regulations, and building over a sewer may need the water company's agreement. Ask the engineer before work starts.