title: Integral quantification of contaminant mass flow rates in a contaminated aquifer: conditioning of the numerical inversion of concentration-time series.
abstract: A series of integral pumping tests (IPTs) has been conducted at a former gasworks site to quantify the contaminant mass flow rates and average concentration in groundwater along three control planes across the groundwater flow direction. The measured concentration-time series were analysed numerically with the help of the inversion code CSTREAM and a flow and transport model representing the highly heterogeneous aquifer. Since the control planes cover the entire downstream width of the potentially contaminated area, they allow conclusions to be drawn about the current location and spread of the contaminant plume. Previous evaluations of integral pumping tests could calculate three scenarios concerning the spread of the plume around the IPT well: (i) the plume is located to the right of the pumping well, (ii) to the left, or (iii) is distributed symmetrically around it. To create a more realistic picture of the plume position, a series of direct-push monitoring wells were installed along one control plane. The concentrations found in these wells were included in the numerical analysis to condition the numerical inversion results, and allowed the identification of a more pronounced plume centre and fringe, which supports the development of optimised remediation strategies.
authors.affiliation: Applied Geology, Geosciences Center, University of Göttingen, Goldschmidtstr. 3, 37077 Göttingen, Germany. mherold@gwdg.de
authors.forename: Maria
authors.initials: M
authors.lastname: Herold
authors.forename: Thomas
authors.initials: T
authors.lastname: Ptak
authors.forename: Marti
authors.initials: M
authors.lastname: Bayer-Raich
authors.forename: Thomas
authors.initials: T
authors.lastname: Wendel
authors.forename: Peter
authors.initials: P
authors.lastname: Grathwohl
mesh_terms: D004784:Environmental Monitoring / Q000379:methods*; D052918:Environmental Restoration and Remediation; D005618:Fresh Water / Q000032:analysis*; D005858:Germany; D008962:Models, Theoretical; D013997:Time Factors; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D014874:Water Pollutants, Chemical