The number of construction projects on sites vacated by factories and enterprises is expected to increase in the future, in which problems of soil pollution or groundwater pollution are likely to be encountered. The Ministry of Construction is carrying out a joint research project in cooperation with 21 private firms The project proposes problems in case of applying analytical programs, to predict the impact of groundwater pollution and to evaluate possible countermeasures in construction site. The studies have dealt with constant sensitivity analysis using numerical programs. As a result, a method of inputting the longitudinal dispersivity turned out to be very important. In addition, from soil column tests using saltwater or organic chlorine compound solution and a large-scale pit experiment, figures close to those noted by Kintzerubach et al. who show the relation between mass transfer distance and longitudinal dispersivity were obtained. Related to aspect dispersivity ratio, an axisymmetric two-dimensional program could be applied at levels of 1/25 and could reappear the contamination area over several % of relative concentration.

1. Introduction

In the joint research project of the Ministry of Construction, titled the "Development of Construction Technology for geoenvironmental preservation," the issues involved in applying analytical programs to actual construction, including predicting the influences of groundwater pollution and evaluating countermeasures, are being studied. An advection-dispersion program for analyzing water-soluble groundwater pollution has already been released for public use in Japan, but it still suffers the following problems in practice:

  1. the effects and sensitivity of input constants (groundwater flow velocity, dispersivity and retardation factor) on the analysis results are not fully understood. Therefore, the accuracy required for setting the estimated value and measuring tests has not been clarified;

  2. Some consider that longitudinal dispersivity can increase as.the distance traveled by pollution increases.

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