Ponds holding

Hafnium neutron absorption capabilities have caused its alloys to be proposed as separator sheets to allow closer spacing of spent nuclear fuel rods in interim holding ponds. Hafnium is the preferred material of constmction for certain critical mass situations in spent fuel reprocessing plants where hafnium s excellent corrosion resistance to nitric acid is also important. 

Land. At this point, it should be possible to determine how much land will be required. Do not forget to include things like holding ponds, environmental buffer area, camp facilities, and rights of way or easements. It may be well to allow some contingency in initial cost estimates for land requirement increases, as more definitive design information becomes available. 

Now you can reconsider the material balance equations by adding those additional factors identified in the previous step. If necessary, estimates of unaccountable losses will have to be calculated. Note that, in the case of a relatively simple manufacturing plant, preparation of a preliminary material-balance system and its refinement (Steps 14 and 15) can usefully be combined. For more-complex P2 assessments, however, two separate steps are likely to be more appropriate. An important rule to remember is that the inputs should ideally equal the outputs - but in practice this will rarely be the case. Some judgment will be required to determine what level of accuracy is acceptable, and we should have an idea as to what the unlikely sources of errors are (e.g., evaporative losses from outside holding ponds may be a materials loss we cannot accurately account for). In the case of high concentrations of hazardous wastes, accurate measurements are needed to develop cost-effective waste-reduction options. It is possible that the material balance for a number of unit operations will need to be repeated. Again, continue to review, refine, and, where necessary, expand your database. The compilation of accurate and comprehensive data is essential for a successful P2 audit and subsequent waste-reduction action plan. Remember - you can t reduce what you don t know is therel... 

Releases to the atmosphere from production facilities and disposal sites have also been reported. Studies have shown that releases of methyl parathion to the atmosphere occur in the vicinity of pesticide-producing factories. At two predominately downwind sites located 1 mile from a plant producing methyl parathion, average monthly concentrations were <0.57 and <0.64 ng/m (Foster 1974). Air emissions from methyl parathion production facilities have been reported to contain 1.0 kg/1,000 kg pesticide produced. In addition, evaporation from holding ponds for pesticide waste potentially contributes 7.4 mg/1,000 kg pesticide produced to the atmosphere (EPA 1978d). 

Waste injection began in June 1975, and waste was first detected in the downgradient southwest deep monitoring well about 260 days later. To analyze the waste s physical and chemical properties after injection, the primary injection well was allowed to backflow into a holding pond for 5 days in November 1977. This waste was sampled periodically (and reinjected when the test was completed). About 4 years after injection began dilute waste arrived at the standby injection well 476 m (1560 ft) south of the primary well. 

The waste hydrochloric acid (HC1) injected at the site was a byproduct of a combustion process at 1633°C (2972°F). When not recovered, the acidic stream was dumped into holding ponds where it was cooled to about 24°C (75°F) before injection. The concentration of injected acid typically varied from 0.5 to 5% HC1, but ranged as high as about 30%. (The pH of injected acid that back-flowed during one blowout incident ranged from 0.5 to 1.3.)... 

Some kraft mills use both aerated and nonaerated basins. The stabilization basin, which may precede or follow the aerated stabilization basin, serves as a polishing or holding pond to remove additional organic materials, including biological solids, or to reduce final effluent discharges to receiving waters. 

The system design is based on two upflow anaerobic bioreactors (ABRs) followed by three horizontal sub-surface flow (HSSF) wetlands cells. The water flows by gravity through the cells. Once treated, the water is stored in a holding pond and subsequently used for irrigation of a tree farm. 

The Trail system has shown that it is possible to design and operate a system year-round that treats high concentrations of metals. In Trail, the contaminated water is treated to the degree that from the final holding pond it is used for irrigation of trees to be planted in areas near the smelter. 

The solubility of chlordecone in water is low (1--3 mg/L) and as with mirex, contamination is more likely to be associated with the particulate matter in the water rather than the water itself. Chlordecone was detected primarily in water samples collected in and around the production facility site in Hopewell, Virginia, and in adjacent waters of the James River estuary. Effluent from the Life Sciences Products Company facility contained 0.1 —1.0 mg/L (ppm) chlordecone, while water in holding ponds at the site contained 2--3 mg/L (ppm) chlordecone (Epstein 1978). Levels of chlordecone in river water in August 1975 ranged from not detectable (<50 ng/L [ppt]) in the York River and Swift Creek areas, to levels of 1--4 pg/L (ppb) in Bailey Creek which received direct effluent discharges from the Hopewell Sewage Treatment Plant. Water concentrations of up to 0.3 p g/L (ppb) were detected in the James River at the mouth of Bailey Creek and in the Appomattox... 

Figure 1. Schematic diagram showing the monitoring system. (A) recompleted well, (B) surface holding pond with WW monitor, (C) WX/WY deep bedrock wells.

A very different approach is to inundate the land in and around a mine, washing away and/or dissolving out pyrites and other acidforming minerals. These waters are then diverted into large holding ponds where they are allowed to remain undisturbed. When isolated in this way, acid-producing substances are prevented from entering the natural environment. 

A cotton farm in Narrabri, New South Wales, was contaminated with irrigation runoff. The 80,000-liter holding pond was treated with a free form of the Orica enzyme. A 90% reduction in methyl parathion was affected within 10 minutes. The final concentration decreased to 0.4 ppb after 1 hour from an initial concentration of 7 ppb. ... 

Swackhamer D, Engstrom D (2000) Toxaphene concentrations in dated sediment cores from a holding pond for kraft bleach effluent. Unpublished data. School of Public Health, University of Minnesota, MN... 

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