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Aquifer Testing Standard Operating Procedure SWE-FSOP-500,•Revision 0 Ahtna Southwest Environmental Operations 4.4 Aquifer Pumping Test Methods The pumping test methods covered in this section include step-drawdown tests and constant rate pumping tests. A step-drawdown test is conducted for the pumping well and is recommended before initiating any constant rate pumping test. The data provided by the step-drawdown test is used to evaluate well performance and determine the optimum discharge for the subsequent constant rate test. The step-drawdown test entails conducting three or more steps of increased discharge while monitoring water level drawdown. This effectively produces successive stepped drawdown curves. Aquifer testing may be discontinued at a well after the step-drawdown pumping test if 1)only a single-well pumping test is planned, and 2)the step-drawdown test provides all the necessary data of a single-well pumping test. The constant rate pumping test method involves pumping water from a well at a constant rate and monitoring the water level drawdown in response to the pumping. Water level recovery may also be monitored after the pumping is discontinued. Water level monitoring may be limited to the pumping well (single-well pumping test) or include one or more nearby observation wells(multiple-well pumping test).The single-well pumping test utilizes a single- well(the pumped well)and a mechanical pump to remove water at a constant rate from the water-bearing unit.The same well is used to measure water level drawdown and recovery in the formation. The multiple-well test utilizes one or more observation wells at selected distances and locations relative to the pumping well. Water levels are monitored in the pumping and observation wells throughout the test duration. The remaining discussion provides the requirements and procedures for step-drawdown tests and single- and multiple-well constant rate pumping tests. These represent minimum requirements as site- and project-specific information and criteria must be incorporated in planning and conducting pumping tests. The project work plans will provide additional requirements and procedures for the specific pumping tests. The procedures below describe the use of pressure transducers and data loggers to monitor water levels during the pumping testing. However, other water level measurement techniques may be substituted, and the procedures may be modified as appropriate in the project work plans. 4.4.1 Step-Drawdown Testing Step-drawdown testing should be conducted before other pumping tests are performed. All newly installed wells should be developed before conducting step-drawdown tests. • Inspect the equipment to be used to ensure that it is in good working order. Equipment used for the step-drawdown testing will vary widely based on site-specific conditions.The project work plans will outline the type of equipment to be used. • M&TE used for field activities will be calibrated by the equipment manufacturer or an approved calibration laboratory using standards that are traceable to the NIST. Certificates of calibration for M&TE will be obtained from the M&TE supplier and kept in the project files. No M&TE will be utilized without verification of calibration certification. • Decontaminate all downhole equipment according to SWE-FSOP-801. Page 13 of 17