Reducing Uncertainty in DNAPL Characterization  
Andrew Bittner, M. Eng. Gradient Corporation, Cambridge , MA
Kurt Herman, M. Eng. Gradient Corporation, Cambridge , MA

Characterization of a VOC Plume Migrating from Fractured Shale into a Karst Limestone Aquifer
Paul G. Landry, P.G., Technical Manager, Weston Solutions, Inc., W. Chester , PA  
Paul R. Stone, III, Project Manager, U.S. Army Corps of Engineers, Chambersburg , PA  
Bryan L. Hoke, BRAC Environmental Coordinator, Chambersburg , PA

Geophysics for Fun and Profit:  How to Manage Your Due Diligence Risk
Jesse N. Japitana, ENSR, Westford, MA
Robert M. Cataldo, ENSR, Westford, MA  

Optimization of the Removal of a Volatile Organic Compound (VOC)-Impacted Source Area through Pre-Characterization
Jeremy J. Picard, Environmental Resources Management, Boston, MA
Jason D. Flattery Environmental Resources Management, Boston, MA
Louis J. Burkhardt, Raytheon Company, Billerica, MA

Wavelets and Spectral Analysis, Powerful Tools for Estimating Aquifer Hydraulic Parameters without Extracting Water
Farid Achour Ph.D., ENVIRON International Corporation, Irvine, CA
Carol Serlin PG., ENVIRON International Corporation, Irvine, CA

Reducing Uncertainty in DNAPL Characterization  
Andrew Bittner, M. Eng. Gradient Corporation, 20 University Road, Cambridge, MA, 02138, USA, Tel: 617-395-5574, Fax: 617-395-5001, Email: abittner@gradientcorp.com
Kurt Herman, M. Eng. Gradient Corporation, 20 University Road, Cambridge , MA , 02138 , USA , Tel: 617-395-5568, Fax: 617-395-5001, Email: kherman@gradientcorp.com

Defining DNAPL extent and magnitude is critical for successful remedy decision-making.  Inadequate DNAPL characterization may lead to inappropriate remedy selection and, ultimately, to a failed or ineffective remedy (i.e., does not efficiently achieve remedial goals).  We have developed two distinct techniques (one based on analytical data and the other on visual observations) to delineate DNAPL extent and magnitude (mass) and combined the results to minimize uncertainty.  As a case study, both techniques were applied at a former manufactured gas plant site with sediments impacted with tar and its constituents [e.g., polycyclic aromatic hydrocarbons (PAHs)].  For the analytical data approach, we estimated the extent of the DNAPL by comparing all measured sediment PAH concentration data with site-specific solubility limits; we then used all of the PAH concentrations within the delineated zone to estimate the mass of tar at the site.  For the visual observation approach, we used field-recorded observations of DNAPL from sediment cores to estimate extents.  We then calculated the total DNAPL mass by assigning representative DNAPL saturation levels.  Individually, each source characterization approach may have uncertainties, but using both allowed us to more confidently estimate the DNAPL extent and mass, which will lead to more appropriate remedy decisions.

Characterization of a VOC Plume Migrating from Fractured Shale into a Karst Limestone Aquifer
Paul G. Landry, P.G., Technical Manager, Weston Solutions, Inc., 1400 Weston Way, W. Chester, PA 19380, Tel: 610-701-7273, Email: P.Landry@westonsolutions.com
Paul R. Stone, III, Project Manager, U.S. Army Corps of Engineers, Letterkenny Army Depot, 1 Overcash Ave, Chambersburg, PA  17201, Tel: 717-261-6863, Email: Pstone3@kuhncom.net
Bryan L. Hoke, BRAC Environmental Coordinator, Letterkenny Army Depot, 1 Overcash Ave, Building 14, Chambersburg, PA  17201, Tel: 717-267-9836, Email: bhoke@emh1.lead.army.mil

Delineation of the NAPL source zone in the vicinity of an oil burn pit (OBP) at Letterkenny Army Depot (LEAD) revealed the presence of source material on both sides of a nearby groundwater divide resulting in a bilobate plume.  While the northern lobe of the plume migrating from the OBP had been well defined, the southern lobe of the plume had been previously undetected.  An investigation was initiated to determine whether the southern lobe of the plume had reached the Pinola Fault (900 ft downgradient), the formation contact between the Martinsburg Shale and the St. Paul Limestone, and if so, what impacts the plume was having on groundwater/surface water quality in the limestone aquifer.  Dye tracing and aquifer tests had shown significant differences in groundwater velocities between the two rock types (ie; ft/year in the shale versus >2,000 ft/day in the limestone).

The migration pathway and extent of the plume moving south was mapped using geoprobe/soil gas sampling, and verified by well installations.  The soil gas results correlated extremely well with the travel path and extent of the contaminated groundwater within the shale.  The strong soil gas/groundwater quality correlation was attributed to both shallow groundwater and slow velocities within the shale, which allowed for the accumulation of soil gas vapors.  In this manner, the plume was effectively mapped down to the fault contact and the plume entry location into the limestone was identified.   VOC sampling results to date indicate minimal impact from the plume on limestone groundwater quality.  Rapid groundwater velocities and extensive karst development result in significant declines in contaminant levels a short distance from the fault.  Dye tracing results from wells at the plume entry location and at numerous downgradient wells throughout the limestone basin appear to substantiate these findings.

Geophysics for Fun and Profit:  How to Manage Your Due Diligence Risk
Jesse N. Japitana, ENSR, 2 Technology Park Drive, Westford , MA , 01886 , USA , Tel: 978-589-3000 x 3394, Fax: 978-589-3705, Email: jjapitana@ensr.aecom.com
Robert M. Cataldo, ENSR, 2 Technology Park Drive, Westford , MA , 01886 , USA , Tel: 978-589-3000 x 3141, Fax: 978-589-3705, Email: rcataldo@ensr.aecom.com

Near-surface geophysics provides an efficient, cost-effective and non-invasive method for the investigation and assessment of property transfers.  When sequenced, implemented, and integrated properly, geophysics can enhance our understanding of site specific subsurface conditions to optimize further intrusive investigation and corrective action.  Having geophysical data allows for a more informed decision-making process when evaluating the benefits and potential liabilities associated with property acquisition.

This presentation focuses on geophysics as an innovative technical approach to manage risk and optimize site investigations.  In addition, the presentation draws on case studies where geophysical investigations were used to confirm suspected underground features or identify previously unknown hazards that would have significantly impacted the development cost and timing of these sites had their existence not been detected.

Optimization of the Removal of a Volatile Organic Compound (VOC)-Impacted Source Area through Pre-Characterization
Jeremy J. Picard, Environmental Resources Management, 399 Boylston Street, Boston, MA 02116, Tel:  617-646-7800, Fax:  617-267-6447, Email: jeremy.picard@erm.com
Jason D. Flattery, Environmental Resources Management, 399 Boylston Street , Boston , MA 02116, Tel:  617-646-7800, Fax:  617-267-6447, Email: jason.flattery@erm.com
Louis J. Burkhardt, Raytheon Company, 880 Technology Park Drive, MS 2-2124-01, Billerica, MA 01821, Tel: 978-436-8238, Fax:  978-436-8581, Email: Louis_J_Burkhardt@raytheon.com

A comprehensive characterization is not typically conducted following source area delineation.  However, pre-characterizing a soil excavation area may yield benefits to a project including: 1) reducing the need for real-time analytical data to support decision-making; 2) allowing for source area soil to be stockpiled based on the detailed characterization data, thereby minimizing the mixing of contaminated and uncontaminated soil; 3) reducing project uncertainties and capping project costs; and 4) reducing the total volume of soil for disposal at a waste treatment facility.

At this subject site the source area soil was delineated using the United States Environmental Protection Agency (EPA) Triad Approach, utilizing a combination of 13 Waterloo Profiler locations, 41 Membrane Interface Probe (MIP) locations, and 20 soil borings.  A source area of approximately 25 foot (ft) vertical thickness over an 80 x 80 square foot (ft2) area was delineated.  The maximum TCE concentration in the source area soil was 57,000 milligrams per kilogram (mg/kg), significantly greater than the regulatory standard of 300 mg/kg.  Excavation of the source area soil utilizing a circular sheet pile cofferdam was determined to be the preferred remedial approach. 

Prior to initiating the remedial approach, continuous soil cores were collected from 41 locations within the excavation area.  These cores were field screened for VOCs and a total of 132 soil samples were submitted VOCs analysis.  The resulting analytical data was used to optimize the performance of the excavation through a better understanding of VOC existence within the source area soils. 

Wavelets and Spectral Analysis, Powerful Tools for Estimating Aquifer Hydraulic Parameters without Extracting Water
Farid Achour Ph.D., ENVIRON International Corporation, 2010 Main Street, Suite 900, Irvine, CA 92614, Tel: 949-798-3622, Fax 949-261-6202, Email: fachour@environcorp.com
Carol Serlin PG., ENVIRON International Corporation, 2010 Main Street, Suite 900 , Irvine , CA 92614 , Tel: 949-798-3660, Fax 949-261-6202, Email: cserlin@environcorp.com

A pumping test involves removing ground water from a well and measuring water levels in the pumping well and surrounding piezometers. When the aquifer is contaminated, the extracted water is to be handled with care. A successful pump test requires time, effort and pump testing equipment, ranging from the pump itself to the holding tank and treatment of the contaminated water, this results in a costly and tedious operation. However, there are alternatives to the standard pump test that are cost effective and “environmentally friendly."

By analyzing the influence of solid Earth tides and atmospheric pressure on ground water natural fluctuation at a contaminated site in southern California, ENVIRON International Corporation developed a methodology to estimate aquifer parameters such as hydraulic conductivity, barometric efficiency, porosity, specific storage coefficient and storage coefficient. These hydraulic parameters were calculated using tools such as Morlet wavelets, correlation and spectral analyses, gain and coherence functions, and Bredehoeft model. 

The originality of this approach is that unlike the traditional approaches developed by Theis and Jacob for porous media and Gringarten and Witherspoon for fractured media, where several   a priori assumptions are made (Aquifer is isotropic, infinite in lateral extent, horizontal, and uniform thickness....), the proposed approach considers the response of ground water level within a well to an external event, indeed, the system is investigated according to it’s response to an event without making any assumption on the lithology, geometry, structure  and voids distribution in the geological formation.

The main advantage of the approach is that it allows the estimation of the above mentioned hydraulic parameters in multiple wells within a short time, leading to an accurate characterization of spatial heterogeneities, therefore efficiently characterize and remediate the site by providing a better understanding of rates and directions of groundwater flow and contaminant transport.