Conceptual modeling

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Conceptual model development This chapter describes the setup of the conceptual model for the Akacievej field site based on a set of field measurements and modeling. Geologic model Data from boreholes, borehole cores, geophyisical measurements, the larger scale geology and expert knowledge were combined to setup a 3D geologic model using the software GeoScene3D. The top of the limestone layer, the transition from crushed to fractured limestone and the transition from the København's kalk to bryozoan limestone were determined in a borehole array and the data was spatially interpolated, to obtain 3D surfaces that can be used in a numerical flow and transport model. A cross section of the geology at the Akacievej site is shown in Figure 1 and described in the Chapter Geology and properties of limestone. Fig.1: Geology at the Akacievej site. Flow field To determine, where contaminants may migrate, it is important to have knowledge about the local flow field. At the Akacievej site, a synchronous hydraulic head measurement campaign to determine groundwater flow field in the larger plume area was done. Therefore, the hydraulic heads in a larger area around the Akacievej site were leveled on the same day. The hydraulic head measurements can be used to develop an isopotential map, which is, for example, required to delineate the model domain. Figure 2 shows the isopotential map that was created for the area around the Akacievej field site. An extent of the measurement area larger than the plume is beneficial, so flow models with little influence of the boundaries on the flow field can be setup. Further, there may be only few boreholes in the vicinity of the contaminated site, which makes it difficult to create a local isopotential map. Fig.2: Flow field at Akacievej determined by head measurements. Determination of aquifer parameters A combination of measures was tested and used to determine the aquifer parameters at the site. A long-term pumping test, short-term pump tests and packer tests, a series of slug tests, a packer test, head measurements of the remediation system and at neighboring waterworks gave information about the hydraulic conditions at the site. A synchronous well sounding round in the larger area allowed to determine the overall groundwater flow field. At the Akacievej site, the remediation system was turned off and on several times while measuring the head changes in the remediation well and in observation wells in the area. The groundwater flow field with the remedial pumping and without could be determined. The following report contains a detailed description of a long-term pumping test that was conducted at the Akacievej site in combination with six tracer tests and PCE measurements: Report about the pumping and tracer test at Akacievej (PDF) Tracer tests, information from outcrops etc. Contaminant distribution and dynamics PCE concentration measurements before, during and after the pumping test, combined with previous investigations. Modeling interpretations and conceptual model of the plume propagation. PCE distribution at Akacievej during remediation Return to Content