HW Prob 2:  Calculate Air Pollutant Concentrations Downwind

   of Air Stripper of Contaminated Groundwater  Due Oct. 16, 2007 in class

Given:  Air Toxic Emission Rates for Air Stripper of Groundwater proposed for

          construction in Kent-Auburn area (South King County, Washington State).

 

 

      Pollutant

  CAS

  Q (grams/sec)

Type

  ASIL (ug/m3)

Annual Average

Vinyl Chloride

  75-01-4

   0.010

   A

    0.012

 

The above ASIL for vinyl chloride was obtained from a Puget Sound Clean Air Agency web site:

    http://www.pscleanair.org/regulated/businesses/regulations.aspx

    http://www.pscleanair.org/regulated/reg3/asil.pdf

 

Washington State type A air toxics are carcinogens.  ASIL = "acceptable source impact level" concentration

of air pollutant in the atmosperhic air.  Most other states use "AAL" or "acceptable ambient air". 

The averaging time for type A ASILs is the annual arithmetic mean (or annual average).

 

          Stack Height                          20 ft           6.096 meters

          Stack Inside Diameter          2 ft             0.6096 meters

          Stack gas exit velocity           10 ft/sec     3.08 m/sec

          Stack gas temperature                   68oF           20oC = 293.33oK

          Ambient air temperature     68oF           20oC = 293.33oK

          Receptor Height                    4.92 ft        1.5 meters

          Land is flat terrain in Kent-Auburn Area (use Rural option)

          Building Height           12 ft           3.658 m

          Building Width              8 ft           2.438 m

          Building Length          16 ft           4.877 m

          Distance between stack base and fence       2 m

 

Find:         

A.  Use SCREEN3 or TSCREEN to find the maximum downwind air pollutant concentrations. 

      Note that the 20 ft high stack is not at the "Good Engineering Practice" height so there will

      probably be plume downwash.

 

1)  Distance to maximum downwind air pollutant concentration:  __________________

2)  Maximum downwind vinyl chloride conc.

 

          a)    1 hr av    ____________ug/m3         b)   Annual Average____________ug/m3

3)  Vinyl Chloride emission reduction needed to meet ASIL  _______________%

 

B.  The engineers designing this groundwater air stripper facility increase the stack height

      from 20 ft to 36 feet or 10.973 meters (the buildling dimensions are the same).

      Run SCREEN3 or TSCREEN to find the maximum downwind vinyl chloride concentrations.

4)  For 36 ft  Stack, Distance to maximum downwind air pollutant concentration:  ______________

5)  For 36 ft stack,   Maximum downwind vinyl chloride concentration:

 

          a)    1 hr av    ____________ug/m3         b)   Annual Average____________ug/m3

 

6)  For 36 ft stack, Vinyl Chloride emission reduction needed to meet ASIL  _______________%

7)  Is this 36 ft stack a "Good Engineering Practice" or "GEP"  stack height?  Explain.