| Contents Notes |
"Treated municipal sludge was used to revegetate three 4-ha demonstration plots in the anthracite and bituminous coal mining regions of Pennsylvania. The three sites selected represented more than 100,000 ha of abandoned, barren bituminous strip mine spoil banks and anthracite refuse banks present in the state. Various types of sludges (liquid digested, dewatered, and composted) were applied at different application rates to supply the necessary nutrient pool for establishing vegetation and to adhere to state guidelines regarding lifetime applications of trace metals on the land. Following sludge application and incorporation, all sites were seeded with a mixture of grasses and legumes. A monitoring system was installed at each demonstration plot to determine the effects of the sludge applications on (1) the bacteriological and chemical qualities of soil percolate and groundwater, (2) soil chemical properties, and (3) the growth and quality of the vegetative cover. Data collected over a 5-year period indicate that the sludge applications ameliorated the adverse site conditions and resulted in a quick, complete vegetative cover that has persisted and improved each year. No deterioration in vegetation yield or quality has been observed on any site. Although sludge applications increased some trace metal concentrations in the vegetation, all concentrations were below plant tolerance levels, and no phytotoxicity symptoms were ever observed. Before vegetation was established, the sludge applications caused some sporadic, short-lived increases in nitrate-nitrogen concentrations in soil percolate water. However, in general, the sludge applications had no significant adverse effects on the chemical or bacteriological quality of groundwater. Study results indicate that stabilized municipal sludges can be used to revegetate mined lands in an environmentally safe manner with no adverse effects on the vegetation, soil, or groundwater quality. The study also shows that at the proper rates, single applications of sludge on a mined site can successfully establish vegetation and sustain it for the 5-year period mandated under the Federal Surface Mining Control and Reclamation Act of 1977." |
