Groundwater Pumping Test Analyses for a Gasoline Contaminated Site at Donnybrook, Western Australia

[摘要] This document reports on a hydrogeological investigation conducted at a gasoline contaminated site in the town of Donnybrook, WA where aquifer remediation of petroleum hydrocarbons was undertaken by the CSIRO. The intention was to estimate aquifer hydraulic conductivity based on data collected from several different types of pumping tests conducted at the site. Only those involving skimming and drawdown or total fluids were considered. Twelve well tests were analysed, involving different conditions (e.g. type of well test, pumping rate and duration, wells used for pumping and observation used in the test). Some of the smaller well tests involved observation wells within a local area of about 10 to 20 m2, whereas some of the larger tests included observation wells over 350 to 450 m2. Comparisons of estimates of hydraulic conductivity were made at different scales and where areas of observation overlapped. In some cases, separate well tests used the same set of wells for pumping and observation, but the pumping rates and durations varied. Results from these provide further insight into hydraulic conditions within the aquifer.Estimates of hydraulic conductivity based on the pumping test results were divided into two distinct areas, Area A to the rear of the site and Area B near the access road at the front of the site. Stratigraphic data relative to the position of the piezometric head during drawdown and the time-drawdown plots compared with theoretical plots were used to deduce the most likely aquifer conceptual model. There is no single uniform conceptual aquifer model applicable across both areas. There are varying amounts of confinement of the sand aquifer, with possible leakage from the overlying aquitard, and in some cases, the pumped strata acted as an unconfined aquifer system after long-term pumping. The estimates of hydraulic conductivity determined from this investigation are of the order of 16 to 45 m/day in predominantly sand layers, and 1 to 10 m/day in predominantly sandy silt and clay layers.

[发布日期] 2019-08-22 [发布机构] CSIRO

[学科分类] 地球科学(综合)