New Jersey Water Science Center
Great Falls of the Passaic River at Paterson, N.J.
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Validation of Membrane Diffusion Sampler
Project Title: Validation of Membrane Diffusion Sampler
This proposed effort will demonstrate a regenerated cellulose dialysis membrane diffusion bag sampler (hereafter referred to as the "RCDM diffusion sampler"), recently designed by the USGS, which can be used to sample for soluble inorganic and all organic (volatile/nonvolatile) contaminants in groundwater. It consists of commercially available flexible regenerated-cellulose dialysis tubing that can be configured to fit small-diameter monitoring wells at low cost, similar to the LDPE sampler. The primary objectives are:
Statement of Problem
Collection of groundwater samples for long-term monitoring or to assess remediation at contaminated DoD sites is very costly in terms of manpower, time, and equipment requirements. The standard technique for groundwater collection is currently the USEPA low-flow purging procedure using a variable-speed submersible pump with disposable discharge tubing (Puls and Barcelona, 1995). The low-flow technique often requires a monitoring well to be pumped for long periods of time (hours) at a low-flow rate (<500 ml/min), until field parameters stabilize and samples are collected. Following sample collection, the pump and its sampling components must be decontaminated before deployment in another well. Normally, the purged groundwater and wash water are drummed and must be transported to treatment facilities offsite for disposal. Groundwater turbidity, often created by pump installation or bailing, is an important field parameter that is seldom allowed to stabilize in the purge step. If turbidity exceeds 5-10 NTU, serious bias can result for many contaminants that sorb with the suspended particulates (Gibs et al., 2000). This introduces uncertainty in the assessment of inorganic and organic contaminant concentrations in groundwater, which can result in incorrect conclusions concerning site water quality or remediation status.
Strategy and Approach
This project will provide demonstration and validation of the RCDM diffusion sampler for monitoring groundwater at DoD sites. Important volatile, semivolatile and highly soluble organic and inorganic constituents that are commonly measured at DoD sites to assess MNA or other remediation techniques will be assessed with the RCDM diffusion sampler. RCDM sampling effectiveness and cost will be compared to that of the USEPA standard low-flow purging technique and with the well-characterized and accepted LDPE diffusion sampler. The project will be undertaken in three parts: