Pumping tests at 10 different places along a planned subway were carried out in a certain city. Some differences from the ideal condition were involved in these tests obtained in a developed area. The major difference is the extension of aquifer; i. e., the basements and underground structures took the role of the barrier of groundwater flow through the aquifer. These effects appeared in the results of the pumping tests near the buildings. The use of the partial penetration well is also different from the ideal condition of the Theis theory for pumping tests.
This report focuses on the way to estimate the test results measured by the three different conditions from the ideal condition of the Theis theory. These are (1) the case in which basement wall of the buildings becomes the barrier of groundwater flow, (2) the case in which the thickness of aquifer varies, and (3) the case in which the pumping and observation wells are partially penetrating into the aquifer.

View full abstract

In this paper are mentioned problems and measures concerned with groundwater that ensued by deep underground development.
Various issues have to be examined during projects undertaking. They are as follows :
(1) to optimize the measures against groundwater during excavation;
(2) to evaluate stabilization of excavating ground effectively;
(3) assessment on environmental impacts.
Considering these issues, projects have to be planned reasonably.
From these viewpoints, it is necessary to determine anisotropic permeabilities for optimal design of measures against groundwater. "Multi-Stage Pumping Test" is used to determine horizontal permeability, kh, and vertical permeability, kv. This test is carried out by pumping up from one section of a deep well which has several screens. Using drawdown data on multi-depth observation points, anisotropic permeabilities are obtained. A method is presented for simple analysis using data in steady state.
This test was applied to- a construction site where deep excavation planned in Tokyo.

View full abstract

In recent years, utilization of underground-space in urban area has increased. In such cases, it is quite important to predict changes in geo-environmental conditions precisely. For such purpose, detailed site investigation and accurate modelling of the underground are indispensable.
In this paper method for long-time measurement of the groundwater behaviour in multilayered aquifers is discussed. Results of groundwater measurements in a three aquifers system are reported, and continuity between the three aquifers is discussed by examining groundwater levels, atmospheric pressure and rainfall. As the result, it is found that not only seepage but also deformation of the ground should be considered in order to evaluate the continuity of multilayered aquifers. Moreover, survey of quality of groundwater and pumping from the lower layered aquifer are proved to be very important for the investigation of the continuity of aquifers.

View full abstract

In 1982 the Environmental Agency conducted the preliminary nationwide survey for groundwater. Then, regarding tetrachloroethylene (PCE), about 4. percent samples of the total 1,499 ones exceeded the guideline of WHO about drinking water quality. On the other hand, in 1984 N-Ward in Tokyo metropolitan Government (TMG),12.8 percent of samples with PCE also exceeded the guideline. It is important to grasp the situation of groundwater pollution and then to find out causes and countermeasures. The purposes of this study are to grasp the temporal variation of the situation of groundwater pollution, to investigate the resident consciousness for groundwater quality by an questionaire, and applicably to analyze the policy for selecting the method of countermeasure in the urban region such as N-Ward in TMG.

View full abstract

[in Japanese]

View full abstract