Example #1 BOD Average = 614 mg/L
  TSS Average = 111 mg/L
  COD Average = 1200 mg/L
  WWAVG = 0.0116 Million Gallons per Month (MGM)

First calculate the ratio of COD to BOD. 1200 divided by 614 equals 1.95. This ratio is less than 2.25 so we know that the following formula should apply.

S = V x 8.34 [A (BOD-200) + B (TSS-200)]
S = 0.0116 x 8.34 x {[0.5043 x (614 - 200)] + [0.1087 x (111 - 200)]}
S = 0.0116 x 8.34 x {[0.5043 x 414] + [*0]}

* Note that no charge applies for TSS because the TSS was below the 200 mg/L surcharge limit.

S = 0.0116 x 8.34 x 208.78
S = $20.20/month
Example #2 BOD Average = 614 mg/L
  TSS Average = 799 mg/L
  COD Average = 1860 mg/L
  WWAVG = 0.0934 Million Gallons per Month (MGM)

First calculate the ratio of COD to BOD. 1860 divided by 614 equals 3.03. This ratio is greater than 2.25 so we know that the following formula should apply.

S = V x 8.34 [C (COD-450) + B (TSS-200)]
S = 0.0934 x 8.34 x {[0.2242 x (1860 - 450)] + [0.1087 x (799 - 200 ]}
S = 0.0934 x 8.34 x {[0.2242 x 1410] + [[0.1087 x 599]}
S = 0.0934 x 8.34 x [316.12 + 65.11]
S = 0.0934 x 8.34 x 381.23
S = $296.96/month