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(Continued from Page 10) ommends analyzing three to six samples over a one year period.
Choosing the proper site for sludge application can almost eliminate the chances for contamination of ground or surface water, according to EPA. The land should have a slope of not more than 6 percent to prevent runoff and erosion. Streams and lakes may be further protected by a requirement for a surrounding buffer zone where sludge application is prohibited.
The pH of the soil is vitally important in site selection. The solubility of most heavy metals tends to increase as soils become increasingly acidic. This means that uptake of metals by plants and downward leaching of metals towards the groundwater will be greater with acidic soils. Therefore, a soil pH of 6.5 or above should be required when sludge is applied to the land, according to EPA.
Moreover, a pH of 6.5 should be maintained for several years after application, since heavy metals may continue to be present in the soil. So
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