Small-diameter casing for standpipe monitoring wells: A comparison of current alternatives

The standpipe monitoring well is the most common and accepted system for monitoring the chemical quality of ground water. The majority of these wells have a diameter of 2 inches or less. The lower cost of the small-diameter wells makes them the preferred choice. However, the technology available to properly develop, sample, and monitor such wells has evolved gradually over the last several years, and with its changes and improvements have been made in the design of the standpipe monitoring well. The variety of threaded couplings used to join sections of casing or screen are quite diverse, and current designs of the flush-threaded type are surprisingly incompatible. The designs differ in the types of threading and seals, the variety of materials, the actual pipe and coupling lengths, the pipe thickness (schedule), and pipe cleaning procedures. A national standard design is needed for flush-threaded casting used to construct monitoring wells.