This is not expected to be a problem with PlumeStop. The clogging of formations with biofilms (not strictly waste products – microbial waste products are in the dissolved-phase) is more commonly associated with long-term / on-going substrate delivery through fixed points such as in anaerobic VOC remedial biostimulation. In such cases, the problem is principally arises due to the concentration of activity in a restricted locality, typically the well-screen and its immediate surround. In the case of PlumeStop, the activity is distributed through the formation rather than localized.
It is perhaps also helpful to note that the biofilms have a positive effect on the degradation. They are produced by a microflora to serve a number of purposes, including protection from toxic shock or sudden environmental change, and to assist in the capture of substrate and nutrients. In a PlumeStop application, the actual bio-matrix we refer to is the combination of microbe, the exuded biofilms and the PlumeStop itself. Within granular formations the net impact of this on permeability would not be significant, although my earlier points from the preceding question refer.