Optimizing short-term plume containment: comparison of well arrangements.

Three well configurations were compared in terms of term ground-water contaminant plume containment. include parallel, octagonal and combination systems. system had three extraction wells upqradient and injection wells downgradient of the contaminant plume. For each system, optimal pumping values and resulting potentiometric surface smoothness were computed for a hypothetical plume. Tested models utilized linear programming optimization and simulation via the response matrix method. The octagonal well configuration required less pumping for a pumping period of 8 days, than did the parallel or combination systems. The octagonal configuration resulted in the smoothest potentiometric surface, in terms of difference in final head at observation wells compared with those at the contaminant source

PC Software for optimizing groundwater contaminant plume capture and containment

Simulation/optimization (S/0) models can be used to speed the process of computing desirable groundwater pumping strategies for plume management. They make the process of computing optimal strategies fairly straightforward and can help minimize the labor and cost of groundwater contaminant cleanup

Drenagem subterrânea no perimetro irrigado de Maniçoba: critérios de dimensionamento e avaliação de performance

This study was carried out on a parallel subsurface pipe drainage system (1.5 ha) installed for this purpose in a Class 3 soil plot of Irrigation Project Maniçoba, BA, Brazil, in order to determine the applicability of drain spacing equations, check some soil hydrological parameters and adjust design criteria. Drain spacing and combination of envelope materials were the variables considered. The drains spacing (L.) was calculated based on parameters determined in situ and using equations of Hooghoudt and Glover-Dumm. Twice the calculated spacing was considered for variation of this parameter. Depth of water table and rain discharges as response to recharge (surface irrigation or rainfall) were registered for drains spaced L = 15 m and L = 30 m also monitoring soil moisture. Eventually, chemical composition and sediments content of drainage water was determined in the laboratory. Results of this study show that the L = 30 m spacing kept better soil moisture regime in the profile. The peak instantaneous drain discharge was 8 to 10 mm/day falling to 4 mm/day or less three days after recharge took place. The mean water table depth during the study was 0.6 m to 1.0 m below ground surface for L = 30 m and 1.2 m to 1.5 m for L = 15 m. Contribution of soil layers below drain level to underground flow was found negligible. Auger hole method proved a very precise one for the determination of hydraulic conductivity in situ. Hooghoudt equation overestimated the spacing in 24% and Glover-Dumm equation underestimated it in 30%. Drainable porosity values found were 7.8% and 24% and drainage intensity factor determined varied from 0.15 to 0.21. Os trabalhos foram conduzidos num sistema de drenagem subterrânea entubado (1,5 ha) instalado nos solos classe 3 do Perímetro Irrigado de Maniçoba para observar a aplicabilidade das equações de espaçamento de drenos usadas, para aferir alguns parâmetros hidrológicos dos solos e para ajustar parâmetros de dimensionamento. Foram consideradas variáveis, o espaçamento entre drenos e uma combinação de materiais de envoltura. O espaçamento entre drenos (L.) foi calculado com base em parâmetros determinados in loco e usando as equações de Hooghoudt e de Glover e Dumm. O duplo do espaçamento calculado foi considerado como variação deste parâmetro. As variações do lençol freático e as vazões dos drenos como resposta às recargas de irrigação superficial (sulcos) e chuva, foram levantadas para drenos paralelos espaçados de 15 m a 30 m, acompanhado os regimes de umidade no perfil do solo. Ademais, foram determinadas em análise de laboratório, as características químicas e a quantidade de sedimentos das águas de drenagem. Resultados do estudo mostraram que o espaçamento L = 30 m manteve melhor regime de umidade no perfil do solo. A descarga máxima instantânea dos drenos é de 8 a 10 mm/dia, caindo a 4 mm/dia ou menos no terceiro dia após a recarga. O lençol freático manteve-se entre 0,6 m e 1,0 m sob a superfície na área com L = 30 e entre 1,2 m e 1,5 m sob a área com L = 15 m. Demonstrou-se a contribuição desprezível da camada abaixo dos drenos ao fluxo subterrâneo, e a precisão do método do furo de trado (auger hole) na determinação da condutividade hidráulica. A fórmula de Hooghoudt sobreestima o espaçamento em 24% e a de Glover & Dumm os subestima em 30%. Os valores de porosidade drenável obtidos foram 7,8% e 24% e do fator de intensidade de drenagem 0,15 e 0,21.