The tubing is stiff enough to be easily handled, yet light and flexible enough to allow site workers to insert the multilevel well hand-over-hand into the borehole. To date, CMT installations have been almost entirely backfilled installations where the sand packs and bentonite seals are poured or tremied from the ground surface. Einarson and Cherry (2002) provide additional information on the CMT system. More information is also provided by Solinst. The Solinst Waterloo Multilevel groundwater monitoring system is a modular MLS designed to collect groundwater data from multiple depths within a single borehole via a series of monitoring ports positioned at specific intervals along 2-inch ID Schedule 80 PVC casing. The various monitoring ports can be connected to a combination of: sampling pumps, transducers, or polyethylene tubes that extend from the ports to the ground surface inside of the PVC casing. The smooth exterior wall of the PVC casing facilitates construction of annular seals between the monitored zones in the borehole via backfilling with alternating layers of sand and bentonite, or using expandable packers manufactured by Solinst. The sections of PVC casing have water-tight joints to prevent hydraulic cross-communication within the well. Depending on the diameter and number of monitoring equipment, the system can have up to 24 ports. The system is described in more detail by Einarson (2006), with additional information provided by Solinst. The Water FLUTe system is a MLS that uses a flexible impermeable liner of polyurethane-coated nylon fabric inflated against the borehole wall to isolate many discrete intervals, each of which is accessed by a sampling tube that extends to the ground surface. The system is custom-made at the factory to the customer's specifications and then shipped on a reel to the site for installation. The system can be used to monitor a few zones in boreholes as small as 2-inches, to boreholes up to 20 inches in diameter where numerous depth intervals can be monitored (most installations are in the 4- to 10-inch diameter borehole range) with maximum depth to date of 1,400 feet. Depth-to-water measurements can be made inside the sampling tubing using small-diameter water-level meters. Optional dedicated pressure transducers facilitate continuous, long-term pressure monitoring. Water FLUTe systems are described further by Einarson (2006) and Cherry et al. (2007) and by accessing the FLUTe website. The Westbay MP system is a modular instrumentation system for multilevel groundwater monitoring acquired by Nova Metrix in 2015, the MP system consists of two parts: (1) the casing system and (2) portable probes and tools that provide a compatible data acquisition system.