Contaminant plumes usually display considerable variations in concentration over small vertical distances. Conventional monitoring wells can be ineffective in defining plumes because long well screens mix water samples of varying concentrations. Worse yet, ambient flow of groundwater in conventional monitoring wells can spread contamination within the aquifer.
Multilevel systems provide groundwater samples from multiple depth-discrete levels (ports) optimizing the amount of information obtained in a single monitoring hole. A transect of Multilevel Systems across a site more clearly identifies the area of maximum concentration.
403 CMT® Multilevel System
The 403 CMT® Multilevel System* provides the simplicity and low cost of a bundle-type installation, with the benefits of backfilling or sealing around a single tube.
The CMT offers low cost multilevel monitoring up to 7 zones in a single tube, with no joints. The narrow 3-Channel System is ideal for installation using direct push rigs. For such installations, bentonite and sand cartridges are available to give reliable seals between zones. Fast installation ensures the hole is not left open to deteriorate or contaminate.
The CMT System uses continuous polyethylene multichannel tubing which is custom-built on site with screened intervals at desired sampling zones. Reliable seals and sand packs can be placed around the single tube using standard backfill methods, or using pre-formed cartridges in the 3-Channel System.
The CMT Multilevel allows detailed 3-D water levels and water samples at an affordable cost. Detailed transect monitoring of plumes using CMT Systems enable zones of high concentrations to be identified quickly, simply, and at less cost. This gives data that allows better decision-making.
Water levels can be accurately established and samples taken using small diameter portable equipment available from Solinst. If preferred, a sampling tube can be dedicated to a channel that is not needed for water level monitoring. Special wellhead seals are also available to allow vapor sampling in the system.
408M Micro Double Valve Pump
The 408M Micro Double Valve Pump has a remarkably small and flexible design. It is a pneumatic pump similar to a Bladder Pump, but using coaxial Teflon tubing with stainless steel valves & filter for high quality sampling.
It is small enough to fit in 1/2” (13 mm) tubing and all channels of the Solinst CMT System. The Micro DVP is ideal for low flow sampling in narrow applications and operates to depths of up to 200 ft. (60 m). A flow rate of 20 – 200 ml/min can be obtained.
401 Waterloo Multilevel System*
The 401 Waterloo Multilevel System* allows detailed groundwater monitoring from many zones in one borehole, without cross-contamination between monitoring zones. When a number of systems are used at one site, a detailed 3-dimensional picture can be obtained for a more accurate assessment of hydrogeological parameters.
In 3” to 4” bedrock boreholes and pre-cased wells, Waterloo packers give permanent seals to isolate discrete zones. In overburden, Systems can be placed within pre-cased holes with packers, or installed using standard tremie placement of bentonite seals and sand packs.
The System is modular to allow ports to be located accurately at desired monitoring zones. The zones are permanently isolated by the packers or seals and each port is individually connected to the surface. Ports can be fitted with dedicated Transducers, Bladder Pumps and/or Double Valve Pumps.
Alternatively, a port may be fitted with a monitoring tube that is left open for use with narrow diameter portable equipment, such as the 102 or Mini 101 Water Level Meter and a narrow diameter Waterra Pump, a Peristaltic Pump or the Micro Double Valve Pump.
Ports, packers and casing lengths are assembled, as needed, into a water-tight PVC or stainless steel casing string. The modular Waterloo System allows complete customization to each application. Systems can be installed on an angle or vertically. A drilling rig is not necessarily required during installation. Monitoring is fast and efficient, especially if dedicated equipment is used.
Removable multilevels are also available. They are similar in design, but use hydraulic pneumatic packers. For shorter term projects these systems are excellent. Multilevel Systems can greatly reduce the cost of groundwater monitoring.
* Patented ® CMT is a registered trademark