G.3.5
The design infiltration rate for deep infiltration shall be determined by performing a constant‑rate infiltration test followed by a falling‑head infiltration test. The Deep Infiltration Test report shall include documentation of the testing procedure, analysis and results to assess infiltration feasibility and an explanation of the correction factor used to determine the design infiltration rate.
The Deep Infiltration Test report shall be prepared by a licensed professional. The test method may be modified due to site conditions if recommended by the licensed professional and the reasoning is documented in the report. Refer to report submittal requirements in Volume II, Chapter 1.
G.3.5.1 Procedure
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Perform the test by adding water (obtained from a potable water source) to the test well to maintain a hydraulic head in the well equal to approximately half the thickness of the unsaturated infiltration receptor soil layer.
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Monitor the flow rate with a flow meter or other method that is capable of measuring flow to within 5 percent of the total flow rate.
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Monitor water levels in the test well with a pressure transducer and datalogger on a maximum of 5‑minute intervals.
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Add water until the rate of water added is constant, or for a minimum of 4 hours.
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Once a constant rate is achieved, the test is complete. Begin the falling head portion of the test. Monitor water levels during the falling until the water level has fallen to a minimum of 5 percent of the total head targeted during the constant rate portion of the test.
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In addition to the required wells, monitor groundwater elevations in nearby monitoring wells as available.
G.3.5.2 Data Analysis
The test data shall be evaluated by a licensed professional experienced in the analysis of well hydraulics and well testing data. As a result of the likely variability in soil conditions, specific methods for analysis of the data are not provided. It is the responsibility of the professional analyzing the data to select the appropriate methodology.