CMT Transects for Mass Flux Assessment
Multilevel Monitoring is Essential. Multilevels provide the most reliable, detailed data for accurate 3-D site assessment. Important advantages include:
Eliminates contaminant mixing in long screened wells - which averages out heads and contaminants, masks narrow zones of contamination and vertical variations, underestimates the extent and concentration levels due to dilution. Multilevels monitor discrete intervals.
Prevents biases due to ambient flow - cross communication of contaminants can occur when different zones in a borehole are not isolated. Properly sealed multilevels avoid ambient flow within a well.
Provides data for Mass Flux Calculations - Calculating the contaminant concentration and flow rate helps determine the maximum contaminant concentration and risk to receptors. A transect of multilevels across the groundwater flow path provides data for mass flux calculations.
Allows optimized remediation design - Using data from multilevels to accurately define the thickness, concentration variations and extent of a plume.
Saves Cost - through reduced permitting and drilling costs; and because narrow tubes allow smaller purge volumes, reduced disposal costs, efficient low flow sampling and rapid response to pressure changes, all reduce field time.
Typical 3-Channel CMT
Installation in Overburden
with Bentonite and Sand
Typical 3 or 7-Channel CMT
Installation using Layers of
Bentonite and Sand
Backfilled from Surface