Patent ID: 7003405

Claim:
A method of estimating the distance from an underground source of volatile contaminant to an in-situ sensor, comprising: a) measuring a time-varying concentration of vapor from an underground source of volatile contaminant using an in-situ sensor located underground; b) generating a time-dependent response curve from the measured concentrations; c) providing an effective vapor diffusion coefficient, D; d) estimating the distance, L, between the in-situ sensor and the contaminant source; e) predicting the time-varying concentration C′ using the effective vapor diffusion coefficient, D, calculated in step c), and using the estimated distance, L, estimated in step d), by using a one-dimensional analytical solution for diffusion of vapor from a fixed source in an isotropic and homogenous porous media; f) generating a time-dependent response curve based from the predicted concentrations; g) normalizing both the predicted and measured response curves; h) comparing the normalized predicted and measured response curves; and i) repeating steps d) through h) as many times as necessary, each time adjusting the estimated distance, L, until the shape of the normalized predicted response curve matches sufficiently well the shape of the normalized measured response curve; j) whereby the estimated distance L is finally estimated upon a sufficient match between the normalized predicted response and measured response curves.