It is commonplace for many subdivision and site condominium proposals to construct test wells in order to demonstrate the suitability of the aquifer to provide an adequate quantity and quality of water from a protected source. Where test wells and an aquifer pump test are required, the following general aquifer test instructions are suggested in order to provide the consultant with reliable information necessary to substantiate the suitability of onsite water supplies.

Well Construction

• Minimum well diameter of four (4) inches.
• The design consultant working with the well driller will establish the depth of the test well. The well should be completed in a formation expected to produce an adequate quantity and quality of water. Well depth should be adequate to provide for aquifer protection in accord with methods specified in rule R 560.408 including:
  • Penetration of an impervious layer not less than 10 feet thick
  • Minimum 50 feet of submergence of top of well screen below static water level
  • Increased horizontal isolation from existing or potential sources of contamination
  • Combinations of the above

Pump Test
After the test well has been completed and fully developed, an aquifer pump test for four (4) hours minimum duration must be conducted. A minimum rest period of two (2) hours should be observed, prior to conducting the pump test. The design consultant is responsible for and must supervise the collection of data during the test.

Pump test data should be collected at frequencies as indicated on the well pump test data sheet (pdf). During the well pump test, the well should be pumped at a constant minimum rate of 10 gallons per minute or at a higher rate felt necessary to satisfy peak demand for the project. Where the test well does not yield a minimum of 10 gallons per minute, it should be pumped at it's maximum expected yield.

Well Recovery Data
Recovery data should be recorded for a period of 90 minutes unless the well fully recovers in less time. Where the well cannot yield a minimum of 10 gallons per minute, recovery data should be recorded following the same schedule of readings as during the pumping period.

Water Sampling
During the last hour of the pumping period, the design consultant should make necessary arrangements for collection of required samples, by qualified individuals, to document water quality. Analyses of water samples shall be performed by a state certified laboratory.