Plumes length

Virtual distances for plume, length A. Dimensionless downwind distance... 

If necessary, the influence of existing vertical flow paths is to be estimated, since otherwise incorrect evaluations can occur about the plume lengths [4]... 

For the data evaluation upon the dimensions of CAH and MTBE ground-water plumes a literature study was carried out. On the basis of the evaluation of 40 CAH pliunes in Germany, average plume lengths of approx. 1080 m and maximum of 8200 m were determined [4]. The longest CAH plume found in the literature exhibits a length of 10000 m (CAH pliune in Germany [6]). 

MTBE plumes are predominantly stable and show a similar plume length as BTEX plmnes [10]. Plumes with lengths of over 150 m and MTBE concentrations of > 100 pg/1 in the more downstream plume sections are very rare [11]. 

The average lengths of MTBE plumes he at approx. 50 m and the majority of the MTBE plumes points to a regressive status [12]. The plume lengths fall below approx. 90 m. 

There are however also exceptions of the previously described plume lengths with clearly larger ranges. In 16 US states, MTBE plumes with lengths between 330 and 1600 m were determined [13]. 

With reference to the presented theoretical views it is to be assumed that MTBE possesses the potential for the formation of longer plumes. This theoretical flnding however contradicts the available data, as the longest determined MTBE plume with maximally approx. 1900 m is clearly shorter than the longest CAH plume with plume lengths of approx. 10 000 m. In this con-... 

In summary, the multitude of field findings from the US clearly indicate that MTBE plumes in most cases are comparatively short, and the determined plume lengths frequently amoimt to 50-400 m. These plume lengths concern predominantly groimdwater contamination arising from gas stations, which are by far the most frequent cause of MTBE groundwater contamination. 

Thus the available results point to the fact that MTBE in most cases does not form markedly long plumes, even though this can be seen in individual cases. This leads to the conclusion that the spreading potential of MTBE is to be classified between the BTEX and the CAH. Available information about the plume lengths of CAH, BTEX, and MTBE are graphically illustrated in Fig. 9. 

Fig. 9 Plume lengths of different organic compoimds maximal and mean values...

Auxiliary information evaluation of experience gained from other cases, literature data on plume lengths (not site-specific), sorption behavior and degradability of pollutants, possible toxic metabolites, general information on suitability of site conditions. 

Two different databases provided ehlorinated solvent site data. The first database, the Hydrogeologic Database (HGDB), provided information on plume length, plume width, plume thickness, and highest solvent eoneentration for 109 chlorinated solvent sites. The second database condensed extensive site characterization data from 17 Air Force chlorinated solvent sites, with information on parent compounds vs. progeny products concentrations, competing electron acceptors, hydrogen, and metabolic by-products. 

Plume length, ft Plume vddth, ft Vertical penetration, ft Highest concentration, mg/L... 

Data eompiled from 17 Air Force sites using the AFCEE (Air Force Center for Environmental Exeellence) natural attenuation protocol showed a median plume length of 750 ft (based on 14 plumes). There were significant differences in plume length for different plume classes, with Type 1 plumes (sites with available man-made fermentation substrates such as BTEX) being shorter than Type 3 plumes (sites without available fermentation substrates). Twelve of the sites exhibiting Type 1 plumes had a median plume length of 625 ft. 

Plume discharges into stream may not represent maximum potential plume length. 

Vertical dispersivity Oft match observed plume length... 

We may assume comparable conditions for fluorocarbon-based pyrolants. Dillehay has described the influence of pressure on the plume length with the following law ... 

Table 8-1. Summary of estimated maximum axial plume lengths and their site characteristics (from Jove-Colon et al., 2001, with permission). 

Site Type plume length plume lengtht depth Comments... 

Crow Butte Uranium Mine In situ leaching 0.63 0.07 — Preoperational/baseline maximum plume length measured to... 

Gunnison, CO UMTRA (Title I) 2 0.4 50-150 Lindgren (1999) reported a plume length value of 1.5 km... 

LLNL Plume 1 Pit 4-5, Explosive Activity 0.43 0.08 — Sampled 2nd quarter 1994 plume length measured to the p U... 

Monticello Millsite, Colorado UMTRA (Title I) 22-2.4 0.42 — Plume length distance measured to a U + U concentration... 

Monument Valley, Arizona UMTRA (Title I) 1.4 1.1 17 7 Plume length for the[U]y>44 ppb region (deep De Chelly aquifer) is... 

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