CYLINDRICAL PIEZOMETER RESPONSES IN A HUMIFIED FEN PEAT

Most studies of peat hydrology have concentrated on processes below th e watertable where pore water pressures and hydraulic conductivity are measured using piezometers. While piezometer head recovery tests in p oorly humified bog peats give responses similar to those expected from rigid soils, a number of studies have suggested that matrix compressi bility might be important in affecting head recovery test results in w ell humified bog peats. Until now no data have been available for humi fied fen peats. We apply the response time theory of Brand and Premchi tt (1982) tor compressible soils, and Hvorslev (1951) for rigid soils, to head recovery test data obtained from open cylindrical piezometers installed in a humified fen peat in Somerset, England. To the best of our knowledge this is also the first quantitative application of comp ressible soil theory for piezometers to any peat. Our results show tha t compression and swelling of the peat matrix do affect the course of head recovery in the piezometers used in the study. We comment on the significance of this finding for the calculation of hydraulic conducti vities and pore water pressures in this peat type.