Reduction of radon in municipal wells in Virginia and Maryland

Approximately 10% of the homes in nor them Virginia use well water. Our measurements show that some exceed 4000 pCi/L, that the average is about 2000 pCi/L, and that a few homes have waterborne radon as low as 300 pCi/L, the USEPA's recommended Maximum Concentration Level. In this area, granitic rocks yield well water with about 5000 pCi/L, felsic metamorphic rocks yield well water with about 2000 pCi/L, and quartz-rich sedimentary rocks average about 1000 pCi/L. Tests of remediation technology showed that passing water through large tanks of activated charcoal removes about 90% of the waterborne radon, but the charcoal becomes less efficient over a few months. Aeration experiments using a blade and experiments using a splash box in large community storage: tanks removed about 60-70% of the waterborne radon, but using both removed about 90%, and the combination does not become less effective through time.