Requirements for Joining Well Screen to PVC Well Casing
Well Management Program
Effective May 12, 2011, the Minnesota Department of Health Well Management Section adopted a policy allowing some alternatives to the connections currently required in rule.
Minnesota Rules, chapter 4725 currently requires that if a screen is attached or connected to plastic casing, the connection must be made by:
- a nontoxic packer (for example, a neoprene rubber “figure K” packer);
- a plastic coupling meeting the dimension requirements of ASTM Standard F480-02 (these couplings are not commonly available);
- flush-threaded joints meeting ASTM F480-02 (monitoring wells and environmental bore holes only); or
- a slip x-thread fitting meeting ASTM D2466-02 (for 4-inch and 5-inch diameter wells, only).
The rules do not require a connection between a screen and casing. For example, a telescoped screen can be installed inside a casing with no packer or other physical connection between the casing and screen.
For all practical purposes, the rules would allow only a telescoped screen (with or without a packer) for plastic well casing 6-inches or larger in diameter because there are no commonly available couplings that meet the requirements for joining a pipe size screen to plastic casing 6-inches or larger in diameter.
In order to provide well contractors with workable options for construction of plastic cased wells 6-inches in diameter and larger, with pipe size screens, the MDH has adopted the following policy:
- The requirements of Minnesota Rules, part 4725.2550, subparts 1 and 2 for compliance with a particular ASTM standard or dimensions are waived for the screen connection to 6-inch and larger diameter plastic casings.
- Plastic parts and related joining materials including solvent cements must comply with Minnesota Rules, part 4725.2550, subpart 3, which requires NSF compliance.
- If a screen is attached or connected to the casing, the connection must be made by a threaded, solvent-welded, or welded joint or by a nontoxic packer (without requiring that the coupling or fitting meet any particular standard or dimensions). For PVC well casing, only a solvent-welded plastic coupling or fitting or nontoxic packer would be acceptable. The plastic coupling or fitting may connect to the screen with threads or a solvent weld.
- Screws must not be used to join PVC casing (including joining casing to screen).
Please note that this policy does not modify the requirement that flush-threaded PVC casing may be used only in the construction of a monitoring well or environmental bore hole, and flush threaded PVC casing must meet the requirements of Minnesota Rules, part 4725.6650.
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