811 marks, GPR surveys, and dig-point verification: what each one tells you
Three different answers to the same question, and why a crew needs all three.
Three tools, three questions
811 marks answer: where do the utility owners' records say the lines are? A GPR survey answers: what did a specialist see under this site on the day of the survey? Verification at the dig point answers: what is under this exact spot right now, just before we dig?
They are not competing methods. They are three layers, and each catches what the others cannot.
What 811 marks are good at, and where they fail
Marks are free to the excavator, required by law, and cover every member utility. They fail on abandoned lines, private lines past the meter, non-conductive pipe without tracer wire, and anywhere the record is wrong. They are also only as precise as paint on uneven ground.
What a survey is good at, and where it fails
A survey from a qualified locator or SUE provider is the most complete picture of a site available before work starts, and it supports design. It is also expensive, takes scheduling, covers only the area surveyed, and ages from the day it is done.
What dig-point verification adds
The crew checks the exact spot, right before breaking ground, with no specialist on site. It takes seconds, so it gets done every time, and it leaves a record. It is the only one of the three that looks at the ground in the moment that matters.
Putting them together
Call 811 on every job. Survey where the cost of a strike is high. Verify at every dig point, every time. The verification step is the cheapest of the three and the one most often skipped.
Common questions
Does dig-point verification replace 811?
No. 811 notice is required by law. Verification adds a check after the marks are down.
Does it replace SUE?
No. SUE produces engineering-grade surveys for design. Verification confirms conditions at the dig point before excavation.