A surcharge will be assessed for waste containing compatible pollutants in concentrations greater than those for “normal wastewater.” The surcharge shall be based on the average analytical result of not less than two unannounced composite samples collected at the monitoring manhole during the month. However, a surcharge for holding tank wastes shall be based on a representative grab sample. Samples shall be collected and analyzed by department personnel at the POTW treatment plant, or by an authorized independent laboratory when required by the director. Sample collection and analysis shall be in accordance with 40 CFR Part 136 as amended.
The following formula shall be used to determine the amount of surcharge:
SURCHARGE = Sbod + Scod + Stss + Stkn + Snh3 + So and g
Sbod = surcharge for BOD =MWU * 8.34 * (DC-NC) * $0.15
Scod = surcharge for COD
=MWU * 8.34 * (DC-F1) * $0.05
Stss = surcharge for Total Suspended Solids
=MWU * 8.34 * (DC-NC) * $0.15
Stkn = surcharge for Total Kjeldahl Nitrogen
=MSB * [(DC/NC) - 1]
Snh3 = surcharge for Ammonia Nitrogen
=MSB * [(DC/NC) -1]
So and g = surcharge for Oil and Grease
=MSB * [(DC/NC) - 1]
F1 = the larger of (DCbod) * 2.5 or 800 milligrams per liter (mg/l)
MSB =Monthly Sewer Bill (dollars)
MWU =Monthly Water Usage (million gallons)
DC =Concentration of the subject parameter discharged (mg/l)
NC =Concentration of the subject parameter in “normal wastewater” (mg/l)
Wastewater
Normal wastewater has the following characteristics:
Ammonia Nitrogen 30 mg/l
BOD 300 mg/l
COD 800 mg/l
Oil and Grease 100 mg/l
TKN 60 mg/l
TSS 300 mg/l
Only the parameters determined to be present will be included in a pretreatment permit and therefore subject to a surcharge. The surcharge shall be added to the customer’s monthly bill.