NOVELTY - An upward flow constructed wetland cell comprises an oxygenated root zone that includes (i) methane-oxidizing microorganisms for aerobically destroying methane produced in lower zones, enabling co-metabolic destruction of at least one of Trichloroethylene (TEC), dichloroethylene (DCE) and vinyl chloride; and, (ii) ammonia-oxidizing microorganisms for aerobically destroying ammonia, enabling co-metabolic destruction of at least one of TEC, DEC or vinyl chloride and a pore-water sample chamber inserted inside a monitoring well for measuring cell performance.    USE - As an upward flow constructed wetland cell (Claimed) for treatment of water contaminated with chlorinated aliphatics particularly for remediation of groundwater contaminated with chlorinated ethane solvents.    ADVANTAGE - The upward flow constructed wetland cell has an improved construction as compared to the prior art design i.e. it comprises ammonia-oxidizing microorganisms in addition to methane-oxidizing microorganisms, which improves biodegradation of chlorinated aliphatics and also incorporates a pore-water sampler for measuring cell performance that offers a greater vertical resolution as desired, compared to an original nested piezometer system. The new pore-water sample chamber incorporates benefits of dialysis bags placed inside a well at discrete depths. The treatment wetland design and imposed hydraulics allows the contaminated groundwater to move upward through the soil layer to the surface, and then flow through an exit weir that is located at the opposite end of the wetland cell from the water inlet pipe and can be adjusted to control the depth of standing water on the wetland surface and water exiting the wetland through the weir can be discharged to a local sanitary sewer. The units can be assembled in series (end-to-end) to a desired length, and can be easily lowered or pushed within the PVC casing of a well, and positioned at a screened interval of the well. The cell is provided with a VITON (RTM: fluoroelastomer) washer that isolates each sampler and ensures that only the water within each targeted interval has contact with the respective pore-water sample.    DETAILED DESCRIPTION - An upward flow constructed wetland cell, comprises: (a) a membrane forming a bottom of the cell and isolating the cell from the environment; (b) a first zone above the membrane for entry of a supply of contaminated ground water; (c) a second zone above the first zone, comprising organic soil for anaerobic dechlorination of polychlorinated ethylene (PCE) to at least one of TCE, DEC and vinyl chloride; (d) a third zone above the second zone, comprising iron rich soil for iron reduction degradation of at least one of TCE, DEC and vinyl chloride; and, (e) a fourth zone above the third zone, comprising an oxygenated root zone, (f) at least one monitoring well extending vertically through at least one zone; and, (g) a pore-water sample chamber inserted inside the at least one monitoring well. The pore-water sample chamber comprises:(i) a solid rod having a long axis and a short axis; (ii) a cylindrical bore into the rod along the short axis forming a cavity; (iii) a porous plate covering the cavity; and, (iv) sampling ports along the long axis into the cavity. The oxygenated root zone includes: (i) methane-oxidizing microorganisms for aerobically destroying methane produced in lower zones, enabling co-metabolic destruction of at least one of TEC, DCE and vinyl chloride; and, (ii) ammonia-oxidizing microorganisms for aerobically destroying ammonia, enabling co-metabolic destruction of at least one of TEC, DEC or vinyl chloride.    DESCRIPTION OF DRAWING(S) - The figure shows conceptual view of water flow through a vertical constructed wetland cell.