Pond Banks

Keywords Costs Environmental concerns Evaporation pond design Evaporation rate Liners Pond area Pond banks Pond depth Social impacts... 

Figure 23.16 Geotextiles used to control fishing pond bank erosion. Courtesy of Professor Chiwan Hsieh, NPUST, Taiwan.

Geomembrane These liners chiefly provide impermeable barriers. They can be characterized as (1) solid waste containment hazardous landfill, landfill capping, and sanitary landfill (2) liquid containment canal, chemical/brine pond, earthen dam, fish farm, river/coastal bank, waste-water, and recreation (3) mining, leach pad and tailing ponds and (4) specialties floating reservoir caps, secondary containment, tunnel, erosion, vapor barrier, and water purification. Plastics used include medium to very low density PE, PVC, and chlorosulfonated PE (CSPE). (The Romans used in their land and road constructions what we call geomembrane.)... 

This definition excludes all systems which do not have a spatial boundary to their synthetic machinery, for example pure RNA replication. The walls of a test tube or the banks of a warm, little pond 1 cannot be included as boundaries in the sense of definition four. 

The design of an evaporation pond must take into account both the volume of concentrate from the plant and the evaporation rate at the selected site. The prevention of salinity in surrounding areas and the contamination of nearby potable aquifers is of great importance and must be carefully considered during the design phase. The major design factors to consider are the pond area, depth, liners and bank size. 

Fig. 7.1 Cross sectional view of the inner bank of an evaporation pond showing depth and freeboard...

The banks around evaporation ponds can be built from the existing soil and excavated earth. It is suggested that a layer the topsoil be removed from the pond area, and the subsoil underneath be used to form the inside of the bank. The outer slope of the bank can be covered in the removed topsoil, as this promotes the regrowth of vegetation (Singh and Christen 2000). An example of this is shown in Fig. 7.4. 

Suggested dimensions for evaporation ponds are given by Singh and Christen (2000), and these can be seen in Fig. 7.5. The banks surrounding the pond should be a minimum of 1 m high and 2.4 m wide to allow for vehicular access. To reduce erosion, it is recommended that the slope of the inner bank should be 1 5 and the outside bank a slope of 1 2. 

The major cost factors of an evaporation pond include pond liners, land preparation, excavation and clearing, site surveying, bank construction, pumps, control systems, disposal of precipitated solids, maintenance and geotechnical investigation of the site (Singh and Christen 2000). Of these, pond liners typically represent the greatest cost (Nicot et al. 2009). 

If artificial castoreum scent marks are placed on the banks of a pond, beavers, C. canadensis, are more likely to visit, destroy, and re-mark the sites as the complexity of the artificial odor composition increases (Fig. 6.14). While some single phenolics from castoreum such as 4-ethylphenol trigger marking (Miiller-Schwarze and Houlihan, 1991), the response increases as the mixture grows to 4, 6,10,13, and finally 15 compounds. A mixture of 14 phenolics and 12 neutrals (mostly oxygenated monoterpenes) released responses almost as strong as whole castoreum (Schulte etal., 1995). 

Countries not favoured with rock-salt must either import salt from more favoured countries, or resort to the cone, of sea-water, or of the brine from salt-springs, etc. Evaporation is not an expensive process in warm countries, or where coal is cheap. The brine is cone, by solar evaporation, in large hollow tanks or ponds exposed to wind and sun, on the shores of the Mediterranean and the Black Seas on the tide-lands around San Francisco Bay and on the banks of the brine-lakes of the United States. According to C. Ochi,5 10,000 tons of salt are annually extracted from the sea-water at Kaoo-Chew Bay (China). 

Field Studies. We have attempted to compare the relative availability of actinides to small mammals living in contaminated environments near ORNL. Shrews, rats and mice have been collected from a 30 year old contaminated floodplain forest ecosystem ( ). Cotton rats (Sigmodon hispidus) have been collected from the banks of a former liquid radioactive waste pond which contains Pu, Am and Cu in sediments and shoreline vegetation. Analyses were performed by isotope dilution mass spectrometry (U, Th and Pu) or by alpha spectrometry (Pu, Am and Cm). 

Figure 4. Comparative accumulation of actinides by small mammals from contaminated soil or sediment relative to the accumulation of plutonium-239. Accumulation factor (AF) = concentration of nuclide in the internal small mammal body -- concentration of nuclide in dry soil. Twelve shrews and seven rats and mice from a floodplain forest were composited to yield four and three separate analyses, respectively. Twelve cotton rats inhabiting the banks of a liquid waste pond (3513) also were analyzed.

Delineate the study area A strip of vegetation on each bank of a stream, up to 30-50 m from the water or in the case of a lake or large pond, lay transects perpendicular to the water s edge, up to 60 m from the shore. Transects can be about 5-m wide. Count all trees or shrubs there, and all trees or shrubs that have been cut by beavers, mostly stumps. Relate abundance (numbers of trees present) and utilization for each species separately in an Electivity Index ... 

Cattails are a grass that grows on the banks of ponds and streams. In late summer they produce brown fuzzy seedpods that feel soft like the tail of a cat. Put several of these pods together in a Cattail Planter. The rich brown color looks like velvet. 

Where the last mining cut has been made, exposing bare rock at the bottom and a cliff-like rocky bank, the cut may in some cases be partly covered with soil material, but often a better practice is to use the cut as a pond for livestock, wildlife or recreation. This is not advisable if the water is too acid to support plant and fish life, or disappears during the summer months. 

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