Cover Story Groundwater sampling Prior to installation of groundwater monitoring wells, groundwater samples can be collected through a variety of direct push tooling. There are several types of retractable samplers available for use in the upper level of the groundwater table. There are also groundwater samplers for determining the condition of the groundwater, when a contaminant is possibly sinking within it. Temporary groundwater monitoring wells can be installed if it is not possible or practical to sample through direct push tooling. If it is known or anticipated that groundwater has been impacted by contaminants or if the groundwater has the potential to be impacted in the future by contaminants in the soil, it is important to implement a long-term monitoring program. To do this, small diameter pre-packed screen groundwater monitoring (direct push), or conventional wells can be installed. Direct push wells Direct push wells are approved and accepted by many regulatory agencies. ASTM International has several methods and procedures directly related to their use and installation. Sizes range from 12 mm to 50 mm inside diameter. The practical achievable depth is based on lithology and the desired well inside diameter size. Less than 27 metres is the average depth, although it is possible to install them to depths of over 35 metres. Direct push wells can be secured exactly like conventional wells and development of the pre-packed section can be a simple surging. They can be used to calculate gradient magnitude and direction and there is a variety of small diameter instruments that can accurately take depth measurements, measure useful parameters and collect samples. Sometimes, for certain lithologies and depths, it is necessary to sample soil in order to achieve the target depth when installing direct push wells. It is very important that all sampling and installation techniques are conducted in a way that does not negatively affect/impact the soil and groundwater. Remedial investigations and remediation Once a site has been properly characterized, a precise and strategic remedial www.esemag.com
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investigation can be conducted. For a complex lithology, above or below the groundwater table, it may be necessary to conduct a detailed and precise investigation to collect data that an engineer can use to develop the remedial action plan. Depending on the contaminant type, subsurface lithology and applicable regulatory requirements, the plan can sometimes be developed based on the data collected during an initial site
characterization investigation. As part of a detailed remedial investigation, a pilot study is conducted to determine the radius of influence and the time that it will take to remediate a certain area. A remedial action plan will include the appropriate course of action for the successful remediation of the site, compliance with all applicable regulatory requirements, the timeline for complecontinued overleaf...
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