Handbook of Solvents - George Wypych - ChemTech - Ventech!

23.1 Natural attenuation of chlorinated solvents 1611
Figure 23.1.13. Chlorinated solvents and by-products, 1995, Plattsburg Air Force Base, New York. [From T.H.
Wiedemeier, H. S. Rifai, C. J. Newell and J.T. Wilson, Natural Attenuation of Fuels and Chlorinated Solvents
in the Subsurface, after reference 88. Copyright © 1999 John Wiley & Sons, Inc. Reprinted by permission of John
Wiley & Sons, Inc.]
RT3D represents a remarkable breakthrough in the development and solving of optimization
models of bioremediation design. It is a modular, three-dimensional simulator capable
of predicting mufti-species (solutes and microbes), bio-reactive transport while
understanding natural attenuation and active bioremediation processes.
23.1.6.4 CS case study - The Plattsburgh Air Force Base
The Plattsburgh Air Force Base (AFB) in New York is a former fire training facility (site
FT002). Activities at FT-002 (Figure 23.1.11) have caused contamination of shallow soils
and groundwater with a mixture of chlorinated solvents and fuel hydrocarbons. Groundwater
contaminants include TCE, cis-1,2-DCE, VC and BTEX. The site is underlain with 4
distinct stratigraphic units: sand, clay, till and carbonate bedrock. The depth to groundwater
in the sand aquifer ranges from 45 ft below ground surface (BGS) on the west side of the site
to zero on the east side of the runway (Figure 23.1.12). Groundwater flow is to the southeast
and the average gradient is about 0.01 ft/ft. l Hydraulic conductivity values for the unconfined
sand aquifer range from 0.059 to 90.7 ft/day. Wiedemeier et al. 1 estimated an average
velocity of 142 ft/yr for the sand aquifer.
The extent of Light Non-Aqueous Phase (LNAPL) contamination at Plattsburgh is
shown in Figure 23.1.13. The LNAPL is a mixture of jet fuel and waste solvents from which
BTEX and TCE dissolve into the ground water (DCE and VC are not present in the waste
mixture). The dissolved BTEX plume (Figure 23.1.13) extends approximately 2000 ft
downgradient from the site and has a maximum width of about 500 ft. BTEX concentrations
as high as 17 mg/L were measured in the source area. Historical data from FT-002 indicate
that the dissolved BTEX plume has reached a quasi-steady state and is no longer expanding.