Hydrogeologic testing in blast-shattered heterogeneous bedrock

摘要

Successful installation of the Enhanced Western Groundwater Control System (EWGCS) at Modern Landfill, York Pennsylvania, USA required detailed hydrogeologic testing and analysis of highly heterogeneous materials. The EWGCS was installed to continue the groundwater remediation program while accommodating the development of a landfill expansion. The EWGCS is composed of blast-shattered bedrock 860 m long, up to 30 m deep and up to 9 m wide. Over 140,000 kg of explosives, loaded into blast holes having an accumulated length exceeding 40 km, were used to produce approximately 150,000 m~3 of modified ground. Clay and silt saprolitic overburden deeper than 2 m was replaced with more permeable sand to collect and convey shallow groundwater. Rock blasting increased porosity from 1.5 to 10 percent, and increased hydraulic conductivity from 10~(-5) to low 10~(-2) cm/s. Groundwater collected and conveyed by the EWGCS is removed at the downgradient end via four extraction wells for on-site volatile organic compound treatment. To verify EWGCS operational effectiveness as the system was installed, the application of innovative hydrogeologic testing analysis procedures was necessary, including traditional, bounded aquifer and numerical analysis methods.