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Protection of Water‐Supply Wells from Contamination by Wastewater a
Author(s) -
Bemhart Alfred P.
Publication year - 1973
Publication title -
groundwater
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.84
H-Index - 94
eISSN - 1745-6584
pISSN - 0017-467X
DOI - 10.1111/j.1745-6584.1973.tb02968.x
Subject(s) - infiltration (hvac) , environmental science , loam , wastewater , silt , soil water , pollutant , contamination , hydrology (agriculture) , environmental engineering , soil science , geology , geotechnical engineering , ecology , geography , paleontology , meteorology , biology
Wastewater disposal by a combination of soil infiltration and evapotranspiration is better than disposal through centralized sewerage systems, because the first alternative returns wastewater nutrients where they belong—to growing plants—rather than discharge the pollutants where they cause damage through eutrophication of lakes and rivers, as the second alternative does. Wastewater disposal by soil infiltration and evapotranspiration achieves advantages for our much abused environment only if three conditions are met: (1) sufficient land area is available, (2) strong microbial activities are evident, and (3) water‐supply wells are protected. The proposed method for design and area calculation of seepage beds stresses—in addition to the quality of soil—the importance of microbial actions to keep the soil pores open. For silt‐loam‐clay mixtures of soils, the required seepage bed area varies from 365 sq ft (34 m 2 ) to 640 sq ft (60 m 2 ) for average households if actions of higher aerobic microorganisms are strong. Water‐supply wells located on the same property are protected from wastewater contamination by natural purification in deep layers of undisturbed soil. The protective distance between mouth of well and seepage bed has a vertical and a horizontal component, the former determined by the depth of the well. The need for a sufficiently long horizontal component influences the required property size. It also depends on the types of soil at deeper layers. For an 80 ft deep well for example, the horizontal protective distance varies from 80 ft (24 m) for silt‐loam mixtures to 140 ft (42 m) for sand‐silt mixtures. Wastewater can be entirely evaporated, if soil infiltration would be a hazard to water‐supply wells. Evapotranspiration beds of 2000 sq ft (186 m 2 ) with strong microbial activity are needed for average households.