Disposal Ponds Research Articles

Environmental Considerations for Fly Ash Disposal

Recent concern about subsurface leaching from fly ash disposal sites has generated research to investigate this phenomenon. Among the constituents of the leachate are soluble heavy metals that are found in high concentrations on many fly ashes. This paper reviews those factors which are most important in heavy metal release and reports on some results from a leachate field investigation at an active disposal pond. The pH, which may be determined by the acid-base characteristics of the fly ash, degree of surface concentration of metals, presence of complexing agents, and soil physical and chemical properties are seen as the major considerations affecting leachate quality and quantity. Alternatives which include the use of lining materials, addition of chemicals to sluice water, conversion to a dry handling system, and selective mixing of fly ashes are considered as possible disposal strategies if greater control is deemed necessary.

Prevention of Damage to Waterfowl on Disposal Ponds in Northeast Colorado: ABSTRACT

Prevention of Damage to Waterfowl on Disposal Ponds in Northeast Colorado: ABSTRACT

Movement of Heavy Metals below Sewage Disposal Ponds

AbstractCoarse‐textured soils below sludge and effluent disposal ponds at two sewage treatment plants were studied. The concentrations of Zn, Cd, Cu, Cr, and Ni in the soils at various depths were determined to investigate the downward movement of these heavy metals below the two types of disposal ponds.Concentrations of acid‐extractable metals (4N HNO3) were greater under disposal ponds than offplant control sites at both treatment plants. Metal enrichment was evident to depths as great as 3 m under some ponds. The depth and degree of metal enrichment depended on the specific pond type and the treatment plant. Metal concentrations were greater under anaerobically digested sludge‐holding ponds than effluent ponds. Concentrations of the metals in saturation extracts of soils beneath the ponds were much greater than those typically found for California soils.The distributions of metals with depth were closely related to the changes in chemical oxygen demands of soil samples with depth. This suggests that the metals have moved as soluble metal‐organic complexes.

Nitrogen and Phosphorus Levels in Soils beneath Sewage Disposal Ponds

AbstractSoil cores at various depths beneath sewage sludge and effluent ponds at two treatment plant locations were collected and the nature and extent of nitrogen and phosphorus movement in the soil was evaluated. The soil profiles at both treatment plants were open and coarse‐textured. Soils beneath sludge ponds were enriched in total nitrogen to 4 and 8 m, the maximum depths sampled. Compared to controls, effluent ponds used more than 10 to 20 years showed enrichment of total nitrogen to depths as great as 4.0 m. Concentrations of NH4‐N considerably in excess of controls were observed to depths of 4.0 m demonstrating movement of substantial amounts of NH4 in soil below sewage waste water ponds.Concentrations of NO3‐N in the soil solutions beneath disposal sites considerably in excess of those found below control sites were observed in situations where samples were collected to the water table (8.5 m and 12.0 m), demonstrating movement of NO3‐N the water table. Phosphorus enrichment of soil (NaHCO3 extractable) was evident to depths as great as 3 m below the ponds.