11 Nov How Do We Know? – Part 1
Cartacoustics sonic locating equipment can find things other techniques simply can’t at depths other methods cannot reach. So, how do we know our equipment works? Answering that question will take a couple of posts, and for this post we will focus on things that have a surface presence.
We have surveyed a number of areas across the country that have manholes, fire hydrants, water valves and gas metering stations that are obvious indicators of subsurface structures. We have taken ASTlive! and probed around these structures, and in particular the storm and sanitary sewers are relevant here. We surveyed along the streets and right-of-ways containing these features and lo-and-behold our acoustic returns come back to us in the right location and at the right depth – as measured by the depth of the manholes, for which we usually use a laser ranger to get the distance to the bottom of the manhole.
So, that’s the first way we know ASTlive! works: it’s detection and depth measurements match the manhole geometry and depth within our tolerances. Ba-zinga! Next up, preexisting knowledge with no surface indications…