Gate Systems

Pour typical weU patterns for contaminant plume containment are described in Ref. 16. The first is a pair of injection-production weUs. The second is a line of downgradient pumping weUs. The third is a pattern of injection-production weUs around the boundary of a plume. The fourth, the double-cell system, uses an inner ceU and outer recirculation ceU, with four ceUs along a line bisecting the plume in the direction of flow. Two other methods of plume containment are bio filters and a fuimel-and-gate system, which are described in the in bioremediation section. 

Figure 17 (1) Diaphragm gating system through primary lip. (2) Diaphragm gating system through dirt lip.

Point gating system through seal outside diameter. 

For instance, a time-gated SPC microscope with four gates exhibits a better maximal (FTG4 = 1.3) photon-economy than a two-gated system (FTGi = 1.5). The latter setup will thus require (F (,2//- if,4)2 = 1.7-fold longer acquisition time than the former because of photon-statistics alone. 

This relatively new application of subsurface dams has proved useful to focus groundwater flow to a recovery area. A typical application, referred to as a funnel-and-gate system (Figure 7.2), involves construction of a sheet pile, or slurry wall,... 

Institute (KI) and the Swedish Environment Protection Board (1) it was found, e.g., that the odour threshold was about 101 3. 8 in two pig bams, each with ca 550 pigs. In one bam the manure system consisted of scrapes and in the other of a sluice gate system. The odour emissions, i.e., the product of odour strength and air flow, are all in the magnitude... 

T0757 Surbec Environmental, L.L.C., Soil Washing Technology T0798 Thermo Nuclean, Segmented Gate System (SGS)... 

T0798 Thermo Nuclean, Segmented Gate System (SGS)... 

Table 1 shows the estimated installation costs of a funnel-and-gate system using the Envirowall barrier technology. The presence of boulders in the subsurface will increase installation costs (D18981F, p. 22). 

TABLE 1 Estimated Installation Costs for an Envirowall Funnel-and-Gate System... 

The vendor states that iron reactive walls installed by vertically oriented hydraulic fracture technology would have lower materials and installations costs than conventional funnel and gate systems (D176958, p. 7). 

Thermo Nuclean developed the segmented gate system (SGS) to segregate radioactive material from contaminated soil. The SGS is a combined system of conveyors, radiation detectors, software algorithms, and computer controls. The SGS diverts contaminated soil onto a conveyor belt that deposits the soil in a container for disposal or fnrther processing. The developer claims that the system removes minimal amounts of clean soil with the radioactive particles, reducing the amount of material requiring disposal. The SGS is commercially available. 

The Waterloo Barrier does not remediate wastes. The contaminant plume must be small enough for enclosure to be practical. The vibration and noise associated with pile driving equipment may be a problem in densely populated areas. Funnel-and-gate system can be problematic because they alter groundwater flow. In bouldered terrain and very dense unconsolidated sediments, the use of sheet piling may not be possible. Steel sheet pile applications are generally restricted to depths of less than 30 m. At some sites it is necessary to seal the barrier system to bedrock. 

At the Dover Air Force Base in Delaware, a Waterloo Barrier was emplaced as part of a funnel-and-gate system in 1998. The sheet piles extended to a depth of 45 ft and were keyed to a clay aquitard. The total costs for the funnel-and-gate PRB were 800,000. This figure included design, construction, materials, and the reactive media (D206097, p. 1). 

Starr, R. C. Cherry, J. A. 1994. In situ remediation of contaminated groundwater the funnel-and-gate system. Ground Water, 32, 465-476. 

The photoelectron pulses from the phototube are detected and processed individually through an adjustable gating system, and subsequently integrated over a predetermined period of time. The output is recorded, or treated by a computer. 

The over-all length of the chute, 58 inches, forces each fruit to rotate completely five to six times during its passage. Since the fruits are injected by a gating system normal to the irradiation chute, they already have some rotational energy in this direction. The effect is to add some gyrating motion to the fruits as they roll through the chute. Each element of the surface is then exposed to the variety of flux patterns as it rotates the five to six complete turns to the exit. 

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