Current through Register Vol. XLI, No. 45, November 8, 2024
Section 47-60-8 - Well Screen8.1. Specifications. -- The well screen must consist of materials that will not alter the quality of water samples for the constituents of concern and that are appropriate for the monitoring environment. The well screen should have adequate wall thickness and coupling strength to withstand installation and development stresses. Each section of well screen should be uncontaminated prior to installation. The minimum nominal internal diameter of the well screen should be chosen based on the particular application.8.2. All monitoring well screens shall be constructed of material that is nonreactive with the constituents in soils and groundwater at the monitoring location. The well screen slot size shall be sized to retain at least ninety percent (90%) of the grain size of the collapsed formation where such is used as filter pack material, or at least ninety percent (90%) of the grain size of the filter pack if material other than collapsed formation is used. In lieu of a sieve analysis, or where other well design considerations require a different slot size, a number ten (10) slot screen size may be used, as a maximum, to retain at least ninety percent (90%) of the filter pack material. Well screen interval lengths should be chosen to adequately monitor the water-bearing zone of interest and to comply with section 13 of this rule. Well screens on piezometers installed for the purpose of determining the elevation of the potentiometric surface may not exceed five (5) feet in length, except where potentiometric surfaces may fluctuate over greater intervals. Note: Well screens for wells other than the water table observation wells and piezometers identified above may vary in length.
8.3. Assembly and Installation. All well screens shall be joined to the well riser by methods described in subsection 7.3 of this rule. All joints shall be watertight. Monitoring wells installed in bedrock using an open borehole may be constructed without a well screen.8.4. Well screens shall be centered in the borehole, using centralizers if necessary, except in the case of nested monitoring wells.8.5. The bottom portion of each well screen or well must be plugged or capped to prevent oversized material from entering the well.