The objective of site characterization is to provide data to support decisions about actions to be taken at the site. Most often the actions are remediation of a source area and/or groundwater plume. The amount of data required to support these decisions varies from site to site depending on contaminants of interest, local geology and hydrogeology. Experience has shown that successful remediation requires an accurate conceptual site model (CSM) such as the one pictured above.
High density data collection is an effective approach to creating an accurate CSM and enabling project managers to design successful remediation strategies. High density data collection refers to sampling in both the plan view (horizontal) and vertical dimensions. In order to be a cost effective approach, efficient drilling techniques must be employed to collect high density samples. The use of direct push sampling and sonic drilling has been demonstrated to meet this need.
Deciding on the right density of data to collect can be a difficult task. The locations (plan view) and frequency (vertical) of samples are based on the understanding of the site (initial CSM ) prior to deployment. The best approach to determining the correct density of data required is to use on-site analysis. With the results in hand in real-time, project managers are able to locate subsequent sampling locations based on the evolving CSM. If on-site analysis is not used on complex sites, there is a substantial risk of over sampling (increase unnecessary costs) or under sampling (inaccurate final CSM) requiring redeployment.
On-site analysis must also be cost effective for this approach to work. This will be the subject of a future post.