Water Stewardship Information Sources
| ID | 303 |
|---|---|
| Citation | Carmichael, V, Allen, DM, Gellein, C and Kenny, S. 2009. Compendium of Aquifer Hydraulic Properties from Re-evaluated Pumping Tests in the Okanagan Basin, British Columbia. BC Ministry of Environment and Simon Fraser University. |
| Organization | Ministry of Environment |
| URL | http://a100.gov.bc.ca/appsdata/acat/documents/r16377/OKbasinpumpingtestcompendium_1245946973880_90e8e7259f9f3605666a4a2d3e58d63d01e32ae1cc4c354deafe179afe888646.pdf |
| Abstract/Description or Keywords | Existing available pumping test data from wells in the Okanagan Basin, British Columbia were re-analyzed to characterize hydraulic properties, such as transmissivity, storativity and hydraulic conductivity, of aquifers in the Okanagan Basin. The data utilized in this study consisted of drawdown data over time for unconsolidated and bedrock wells collected by Ministry of Environment staff, hydrogeologic consultants and well technicians from 1964 to 2005. The data were analyzed using a consistent methodological approach, which included use of the derivative method to identify the test period of radial flow during which log-log type curvematching (Theis, Neuman) and semi-log straight-line (Cooper-Jacob, Theis Recovery) techniques were then applied. Time-drawdown data from a total of 164 pumping wells were analyzed within this study, using 180 different data sets. These included one-time tests in isolated wells, tests of wells with groundwater level monitoring at one or more observation points, or multiple tests conducted on the same well with a short time period or with an interval of years between the tests. There were 129 pumping tests (118 wells) for wells completed in unconsolidated (i.e., sand and gravel) materials and 51 pumping tests (46 wells) for wells completed into bedrock. There were 36 storativity estimates generated from 32 different pumping tests (18% of all pumping tests had data from one or more observation wells). Positive boundary conditions were observed for 33% of the bedrock wells (15 wells), 36% of pumped unconsolidated wells (43 wells), and 22% of the unconsolidated observation wells (9 wells) and are thought to be mainly associated with the influence of adjacent surface water bodies, major fracture zones or spatial heterogeneity (i.e., the drawdown cone intercepted aquifer areas of higher transmissivity) in aquifer materials. Negative boundary conditions were observed in 7% of the pumping tests for wells completed into unconsolidated materials and 0.6% (4 wells) for wells completed into bedrock. Boundary conditions were often seen toward the end of a pumping test, indicating the benefit of evaluating aquifer properties over a longer-term pumping interval (24 hours or greater). The derivative method was used to identify stages of borehole storage, radial flow, or boundary conditions in all data sets. For unconsolidated aquifers, transmissivity ranged from 0.26 m2 /d to 24,000 m2 /d (21 to 1,900,000 USgpd/ft), storativity ranged from 0.00014 to 0.18, and hydraulic conductivity ranged from 0.30 to 4200 m/d. For bedrock aquifers, transmissivity ranged from 0.013 to 39 m2 /d (1.1 to 3100 USgpd/ft), and hydraulic conductivity ranged from 0.0018 to 34 m/d. Storativity was only calculated for two bedrock wells and ranged from 0.00028 to 0.0014. Proper pumping test practices greatly assist in the interpretation and the value of the pumping test data. This study demonstrates the value of using a consistent methodological approach to analyzing pumping test data as well as presenting and reporting out on the results. The outputs from this work will be made available to researchers and consultants who are working on developing conceptual, analytical and numerical flow models for aquifer characterization. It is recommended that more studies of this type can be completed in British Columbia to enhance the knowledge and understanding of groundwater in the province. |
| Information Type | report |
| Regional Watershed | Okanagan |
| Sub-watershed if known | |
| Aquifer # | |
| Comments | |
| Project status | complete |
| Contact Name | Vicki Carmichael |
| Contact Email | [email protected] |