· Michael Blair
Excavation is the point at which mistakes become dangerous rather than expensive. A few steps beforehand remove most of the risk.
Call 811
Free, legally required in Tennessee, and it takes a few working days. Utilities mark the location of gas, electric, water, sewer and communications lines on the property.
It marks public utilities up to the meter. Private lines — a gas run to a pool heater, irrigation, a septic field, low-voltage lighting — are not marked and are your responsibility to know about.
What the marks mean
Colour-coded paint and flags: yellow for gas, red for electric, blue for water, green for sewer, orange for communications.
They indicate approximate location, so hand digging is required within a tolerance zone either side rather than machine excavation right up to the mark.
- Call 811 and allow several working days
- Private lines are not marked — know your own
- Hand dig within the tolerance zone around marks
- Check permit requirements before starting
- Know where the spoil is going before you dig
Permits and rules
Depth, proximity to a boundary, work in an easement and anything affecting drainage patterns may all bring requirements. Retaining walls above a threshold height do.
Easements are the trap — you may own the land and the utility retains the right to access it, which limits what can be built there.
Where the soil goes
Excavation produces far more spoil than people expect, because disturbed soil occupies more volume than it did in the ground.
Plan for removal or a place to put it before starting, or the project stalls with a large pile in the middle of the garden.