Groundwater level

The groundwater level is important in the design of borehole systems since the depth of the borehole below the groundwater level is the so-called active borehole depth, i.e., the part of the hole that provides the heat. If... 

Figure 61. Lowering of the groundwater level. By pumping in air at top of the borehole...

With an airproof lid on top of the borehole and an air valve it would be possible to pump air into the casing. This way the groundwater level will be lowered, to preferably a bit above the lower edge on the casing as shown in Figure 61. 

Groundwater level shift (ex-, infiltration), salt (wedge) intrusions near estuaries... 

The PetroTrap was developed by Enviro Products, Inc., who later introduced the PetroTrap-E for sites with minimal fluctuations in the groundwater level. Both products are currently in use and are commercially available. 

The In Situ Saturated Zone Treatment (ISSZT) is a commercially available, U.S. Patented technology that separates groundwater from contaminated soil by applying and maintaining low-pressure air to the contaminated area. The groundwater level in the contaminated area is... 

For ISSZT, a physical barrier, such as a slurry wall or vertical membrane barrier, is installed around the area of contamination to a depth that will be slightly below the future lowered groundwater level to limit the escape of air from the area. Existing clay or silt may serve as a cap for the system, otherwise a man-made cap is installed. Wells are installed into the soil to inject the low-pressure compressed air beneath the cap. As the air pressure increases, the groundwater is lowered. The injected air is prevented from escaping by the cap at the top, the barrier along the sides, and the water table at the bottom. 

Tong, N.T. (2001) Report on Investigated Results for Arsenic Groundwater Level in Ha Noi City, Geological and Mineral Survey of Vietnam. 

Annex V in the WFD describes the framework for groundwater monitoring it specifies monitoring of the quantitative status (by measuring the groundwater level) and chemical status. 

Sudden changes in temperature of this type cause very severe damage to the wood and flower buds of sensitive varieties (e.g. Gala, Elstar, Jonagold, Braeburn) as well as root damage to rootstocks (e.g. quince and M9). It has been found that sunny slopes, hollows and sites with a high groundwater level (moist, cold soil) are most at risk in this respect. 

Reliable groundwater pressure data in shallow parts of a subaerial basin can usually be derived from information on groundwater levels as monitored in open boreholes for the benefit of e.g. groimdwater resource studies for public water supply or agricultural purposes. 

The groundwater level in the soil has no detectable effect on Hg patterns. At Shanbaidu, anomalies over mineralisation occur in low ground near to a river and are often covered by flood waters samples from depths of 60 and 80 cm actually come from below the water table at this locality, but show good anomalies (Fig. 13-9). Similarly, rainwater run-off has no detectable effect anomalies on a slope overlying mineralisation at Tongshan show no downslope displacement (Fig. 13-5). 

As water moves through the soil, either by fluctuating groundwater levels or capillary action, this mobile aqueous iron species is dispersed. If the water table drops, however, the reduced Fe(HC03)2 is exposed to more oxygenated condition, resulting in the formation of oxidized (Fe3+) minerals such as Fe(OH)3 (Fig. 4.25). 

---