Standards Development

Scope

This International Standard develops response sensitivity analysis for groundwater monitoring wells using water injection test method.

Procedures and accuracy requirements for the response sensitivity analysis before measuring water levels in a flowing well are also included.

This International Standard discusses the advantages and limitations of response sensitivity analysis and requirements for recording the data.

This International Standard suggests the practice of response sensitivity analysis for engineers shall be carried out at least once a year for long-term groundwater monitoring wells.

This International Standard states groundwater monitoring wells shall be redeveloped using the same techniques that are used for developing newly-installed monitoring wells in order to make sure all longterm groundwater monitoring wells function well.

Purpose

The proposed standard targets to establish a set of scientific, rationale and operable procedures for engineers to understand the correct method for inspecting the performance of long-term groundwater monitoring well and its implementation. A response sensitivity analysis of groundwater monitoring wells using water injection test method can be carried out to make sure that groundwater monitoring well works effectively. A rating of response sensitivity indicates that groundwater is naturally well protected from the influence of the surrounding conditions, while high sensitivity ratings indicate that, in general, groundwater could be easily and quickly impacted by subsurface activities. Improper operation or error in data processing can be avoided to minimize misinterpretation in testing results. Requirements are specified for the design and construction of groundwater monitoring wells. Inspection standard practice for groundwater monitoring wells are derived. For long-term monitoring wells, some level of maintenance at some time during its usable life shall be required. One common problem in monitoring wells is that the pores of well casing are partly or fully blocked for many reasons, another common problem in monitoring wells is the accumulation of sediment in the bottom of the well. If response sensitivity analysis shows a rating of high level by using water injection test method, those groundwater monitoring wells shall be redeveloped using the same techniques that are used for developing newlyinstalled monitoring wells in order to make sure all monitoring wells function well.

Groundwater monitoring is widely applied in many geotechnical projects, e.g., dam piezometer monitoring, dewatering measure of deep excavation, and uplift design of underground structures. Hydraulic departments recommend to conduct safety assessment for dams in every 5-10 years. The water level in groundwater monitoring wells and its response sensitivity in readings are the key factors in dam safety assessment. Traditional methods adopt groundwater monitoring wells with a large diameter to work as the monitoring borehole. Due to the advantages of large borehole diameter, easiness in borehole cleaning, and good control in construction, the monitored water level inside the groundwater monitoring well can well reflect the groundwater level. However, small diameter groundwater monitoring well is often used to reduce the costs associated with monitoring. With a small borehole, sediments in groundwater monitoring well can cause blockage, reducing the groundwater flow, such that the monitored water level cannot reflect the true groundwater level. Now how to evaluate the true groundwater level using different sized monitoring well becomes important, and a standardized method can be proposed to assess the quality of the network of groundwater monitoring wells. The response sensitivity analysis should be carried out firstly to fulfill the needs of long-term groundwater monitoring.