Project Abstract

Large Scale Model for Anaerobic Bioremediation at the Seal Beach Site

Principal Investigators

Martin Reinhard and Peter K. Kitanidis
Stanford University
E-mail: reinhard@stanford.edu

Goal

The goal of this project is to develop a general transport model applicable to the Seal Beach site, identification of additional hydraulic data needs, and incorporation of biotransformation rate experessions into the overall model.

Rationale

Increasingly, intrinsic and anaerobic biotransformation are considered an option or the remediation of fuel-hydrocarbon contaminated sites. Modeling tools are needed which predict the fate of BTEX contaminants under different geochemical conditions and for the design of monitoring programs.

Approach

Computer models are being developed to interpret contaminant behavior in the test zone and to model processes at the regional scale. MODFLOW and BIOPLUME II will be used to model the processes at the regional scale. These model will allow us to organize the available data at the regional scale and to evaluate possible regional response scenarios to the purposed remediation techniques. Two separate computer based models are being developed to model the treatment zone in detail. The first of this models is relatively simple and will be used in the planning and design stages of the scaled up project. The model assumes that the aquifer is homogenous and neglects dispersion and transformation reactions. The model calculates the flow field analytically and then uses this flow field to calculate solute travel times and the zone of injection influence. Although the model is idealized. it will aid in placing the observation wells. A second model considers the transport and reactions of multiple-species including the BTEX compounds, the electron acceptors and sorption onto and desorption from the aquifer solids. This model will be use to evaluate a number of possible response scenarios within the test zone. The model will also aid in estimating the bulk rate of biodegradation and in understanding what factors influence this rate and how this rate differs from those observed in the laboratory or at the small scale slug tests.

Status

The computer model for the evaluation of slug tests with reactive solutes has been completed. It has been used to match reaction rates to the observed response. The two models of the processes occurring within the scaled up test zone are working. Currently reaction parameters derived from the previous tests and model are incorporated in the new models. As more data is gathered from the site and as our ability to describe the processes occurring at the site improves the models will be modified to reflect this.