The objectives of the research project were to develop and evaluate a method for determining residence times for separated recirculation cavity flow conditions, and to determine the rate of growth and surface ramp contours developed from particulate deposits at obstacles which induce separation and eddy formations in water mains used to distribute drinking water. Resulting biofilm formations contribute to accelerated corrosion rates, increased flow resistance, and the formation of encrustations and colonization that may lead to water quality deterioration. The dependency of conditions at the pipe wall on viscous flow parameters was identified from experiments and analysis of simulated biological growth and decay rates.