N.Y. Comp. Codes R. & Regs. Tit. 10, app 5-D § 5-D.4

Current through Register Vol. 46, No. 50, December 11, 2024

Section 5-D.4 - Well Yield and Water Flow

Before being put into use, new and redeveloped public water supply wells shall be tested for yield as specified in this section. Where adequate hydrogeologic information and uniform conditions exist, or when an experienced hydrogeologist or licensed professional engineer directs and certifies the test, yield testing requirements may be modified by the local health department having jurisdiction. Additional yield test requirements may need to be met for other agencies having jurisdiction.

(a) Pumping yield tests shall be done for the minimum duration of time specified in Table 2. For wells completed in unconsolidated deposits, constant flow rate testing may be used. For wells completed in rock, a minimum of six hours of stabilized drawdown should be observed either at the end of the test or as a second test except as allowed under subdivision (d) of this section or except where the Department or local health department allows constant rate testing.

(b) Where water wells use ground water sources potentially influenced by surface water as indicated in Table 2, water quality shall be tested and/or monitored during the pumping yield test in accordance with Department guidance for the determination of ground waters under the direct influence of surface water.

(c) Periodic water level observations shall be made and recorded during initial drawdown, stabilized drawdown, and recovery periods. The recorded data shall be provided in tabular form to the local agency(ies) having jurisdiction. During the period of stabilized drawdown the stabilized water level shall not fluctuate more than plus or minus 0.5 foot (i.e., within a vertical tolerance of one foot) for each 100 feet of water in the well (i.e., initial water level to bottom of well) over the duration of constant flow rate of pumping. The water level at the endpoint of the stabilized drawdown period shall not be lower than the water level at the beginning point of that period. Water level measurement may be determined by steel tape, calibrated pressure gauge attached to an air line terminating at least five feet above the pump intake, electric sounder, or pressure transducer.

(d) If a stabilized pumping level is not achieved during the required test period or if the well does not recover to 90% of the initial water level within 24 hours after cessation of pumping, a thorough evaluation of the expected sustained performance of the well during seasonal or multi-year dry periods shall be prepared. This evaluation may involve additional hydrogeologic investigation. Such evaluation may be used in lieu of satisfying the objectives of subdivision (c) of this section only at the discretion of the reviewing agency(ies) having jurisdiction.

(e) The test shall be conducted at a pumping rate at least equal to the design pumping rate based on system demand.

(f) Water discharged during a yield test shall be discharged in a manner that avoids short circuiting of the pumped water back into the aquifer.

(g) For wells that have been subjected to hydrofracturing, the yield test shall not commence until redevelopment has been completed and, as a minimum, until the volume of water pumped/discharged into the aquifer has been removed from the well. After pumping, the hydrofractured well shall receive a water well yield test as outlined in this section.

N.Y. Comp. Codes R. & Regs. Tit. 10, app 5-D § 5-D.4