High-resolution Baseline Surveys for focusing remediation efforts

Ned Tillman, COLUMBIA Technologies, 1450 S Rolling Rd, Baltimore, MD, Tel: 410-536-9911, Fax 410-536-0222, Email: ntillman@columbiadata.com William “Tripp” Fischer, DNREC, 391 Lukens Drive, Riveredge Industrial Park, Newcastle, DE, Tel: 302-395-2500, Fax: 302-395-2601, Email:  william.fischer@state.de.us Thomas Numbers, MECX, LLC, 3005 Margaret Jones Lane, Williamsburg, VA 23185, Tel: 757-220-6666, Fax:  757-220-3396, Email: thomas.numbers@mecx.net

With the emergence of Pay-for-Performance Contracting, it has become increasingly critical to have better site characterization data in order to create high-resolution and more accurate conceptual site models.  Without such clarity, all the risks of the unknown site conditions will be either built into an inflated price proposal or underestimated, causing the selected low bidder to cut corners or request numerous change orders to make up for the unexpected cost overruns.  It is in no ones’ interest to proceed with insufficient knowledge about site conditions.  Currently State Pay for Performance programs are struggling with how best to deal with large spatial data gaps, prior to going out for bid.

Historically, many remediation efforts have failed due to inadequate site characterization and/or over-generalized and misleading conceptual site models.  This resulted in costly remediation efforts that do not achieve the clients’ expectations or their regulatory goals, cost-effectively, if ever.  Today, many older remedial technologies are being reassessed, optimized and in many cases replaced by new emerging, remedial technologies or a combination of technologies are being implemented.  In some cases, the redesign still does not have an adequate amount of information for creating an efficient remedial system. This is proving to be costly as well as an ineffective way to do business.

The need for total mass characterization including sorbed, dissolved, free-phase liquid and vapor phase site data both pre and post application of the remedial technology(s) are critical to project success.  Fortunately with the emergence of a variety of direct sensing tools such as the Membrane Interface Probe and optical methods (fluorescence) much more information can be collected in a short amount of time and more accurate site models can be built.  These tools gather thousands of measurements on the geology, hydrology and nature and extent of the subsurface contaminants. The data can be processed into high definition 2D and 3D images of the site, which provides the bidder with much more detail than is normally available for designing a remediation approach.  With this detail, both the bidder and the regulator will be able to determine what areas can be remediated and which cannot, resulting in more realistic expectations of the remediation effort.

To determine the effectiveness of the remediation effort, additional surveys can be conducted post application of the selected technology(s).  These surveys reveal not only reveal the success of the efforts but also show where the chemicals may have been mobilized. In some cases, they will show where a subsequent application is necessary.  Direct sensing surveys are both time and cost-effective in providing much more realistic assessment of subsurface conditions than a limited number of monitoring wells or discrete samples spread throughout the application area.

Top