Well specific capacity

The figure illustration shows occurrence of clogging by plotting data from an observation well (OW) and compare that to the production well (PW). In this case the production well shows a decreased specific capacity while the observation well shows a steady level versus time. The only explanation is then that the resistance for water to enter the production well is increasing. The increased resistance will lower the drawdown inside the well, while the groundwater table outside the well is kept constant. This will increase the hydraulic gradient (the driving force) between the well and the aquifer and hence maintain a constant flow rate. 

It is known about the existence of lithium silicide, Li6Si2, which is close to intermetallic compounds, and also that silicon is capable to form with lithium different alloys. We have calculated the theoretical specific capacity of such possible compounds, as well as pure silicon (Table 2). It is possible to explain from the Table 2 the noticeable increase of capacity for graphite electrodes (11%) even at the small content of Si (3wt%). We can suppose that some of such compounds (LixSiy) with high capacity may form... 

The solid-state character of the graphite material has a great influence on the electrochemical behavior of the LiC . Natural graphite (NG) has the highest crystallinity, and the specific capacity approaches the theoretical value ATs,th = 339 Ah/kg for LiCfi [176]. Practical values around 350 Ah/kg are actually found. Staging, as determined by X-ray diffraction (XRD), is well developed. The potentials are close... 

Computations may be carried out by optimizing the parameters of the applied equations as well as the specific capacity of adsorbed phase for obtaining the best fit of theoretical excess isotherms to the experimental data. Tables presented below contain the characteristics of the adsorption systems from Table 1 illustratively used for computations and the calculation results obtained for Eq.(7) combined with substitutions (27) or (29) under the assumption that n = const. 

Slot sizes of the screens are chosen to maximize well yield so that reliable water samples and water-level drawdown data can be collected during specific-capacity and other field tests. To accomplish this, sieve analyses can be performed on split-spoon samples from the interval to be monitored. A grain-size distribution curve can be field plotted and analyzed to establish the screen slot size and the size of the gravel pack. For wells installed in competent bedrock, it may be wisest not to install a screen but to leave the hole open for maximum yield. In these cases, a surface casing is installed to prevent the collapse of the unconsolidated sediments and possible downward migration of contaminants. 

The commonest way of recovering groundwater is to sink a well and lift water from it (Fig. 4.12). The most efficient well is developed so as to yield the greatest quantity of groundwater with the least drawdown and the lowest velocity in the vicinity of the well. The specific capacity of a well is expressed in litres of yield per metre of drawdown when the well is being pumped. It is indicative of the relative permeability of the aquifer. Location of a well obviously is important... 

Specific Capacity. The determination of specific capacity is a useful procedure to evaluate the magnitude of the expected yield of a well. It is obtained by simply dividing the tested well yield in gallons per minute by the drawdown of the well in feet (gpm/ft). Drawdown is a measure of how much the water table is lowered as a well is pumped. The purpose of this test is to ensure that the well can sustain a required minimum yield over the long term. 

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