Atmospheric Dispersion Stack Evaluation


  • To determine the operating efficiency of an atmospheric dispersion stack in terms of resultant Maximum Ground Level Concentration of dispersed contaminants
  • To ensure system regulatory compliance and / or to ensure maximum
    odor unit reduction at receptor sites


  • Measure gas volume, temperature, pressure, humidity, perform primary compositional analysis
  • Speciate and quantify residual contaminants to be dispersed by discharge stack, calculate mass emission rates
  • Examine the potential for significant variances in major dispersion parameters including stack flow rate, gas condition, mass emission rates etc. as they impact on atmospheric dispersion
  • Evaluate stack physical dimensions and discharge conditions for building downwash caused by adjacent structures, stack tip downwash, and other influences that may adversely affect plume rise characteristics
  • Perform computer dispersion modeling using Screen3, ISC ST3, or other appropriate regulatory model to estimate Maximum GLC of regulated and unregulated constituents as required


  • Provide a written report outlining the pertinent physical and effective parameters of the existing discharge stack.
  • Summarize in table form the stack modeling parameters and mass
    emission rates for each constituent identified
  • Provide computer model output files for each modeled parameter,
    complete with estimates of Maximum GLC and compare maximums
    with regulatory limits in table form
  • Make specific recommendations for improvement in system design as warranted