The City of Lubbock's Industrial Waste Monitoring and Pretreatment (IWMP) department is assigned to monitor the wastewater streams of industries and businesses within the city limits. Our main duty is to protect the Publicly Owned Treatment Works (POTW) through regular inspections and sampling of wastewater streams that flow into our collection system.
We test for harmful pollutants and high strength discharges. High strength discharges are those discharges, which contain a higher Biochemical Oxygen Demand as measured in the standard five day test (BOD5)
and Total Suspended Solids (TSS) than domestic wastewater. The high strength wastes are more difficult and therefore more expensive to treat. To recoup the extra expense of treating the high strength wastewater, the City Of Lubbock can charge the producer of the waste a surcharge. This action is in accordance with Chapter 22, Article 22.04, Division 2, Section 041(c) of the City of Lubbock Sewer Ordinance, which states:
Surcharge: Sewer customers or others discharging wastes to the sanitary system which do not exceed the limits established in Section 084 of this Ordinance, and which do not exhibit any of the characteristics of wastes prohibited by Sections 083 and 085 but have concentration(s) in excess of “normal domestic sewage”, shall pre-treat the wastes to meet the concentrations of "normal domestic sewage"; however, such excessive BOD5 and TSS wastes may be accepted for treatment if all the following requirements are met:
- The wastes will not cause damage to the wastewater collection system;
- The wastes will not impair the City’s treatment process;
- The wastes will not cause contamination of POTW sludge’s thus limiting sludge disposal options or practices;
- The person(s) or owner(s) responsible for the wastes pays a surcharge, in addition to the regular water and sewer rates, in accordance with the following cost factors and formula:
V = Million of gallons (MG)
BOD = Biochemical oxygen demand analyzed in accordance with the latest edition of "Standard Methods for the Examination of Water and Wastewater", or the latest EPA approved method, and reported in units of milligrams per liter (mg/l).
TSS = Total suspended solids analyzed in accordance with the latest edition of "Standard Methods for the Examination of Water and Wastewater", or the latest EPA approved method, and reported in units of milligrams per liter (mg/l).
Cost Factor BOD5 = 55% of the total budgeted costs for operating and maintaining the wastewater treatment facilities divided by total pounds BOD5 treated, current cost factor is $0.2954 per pound.
Cost Factor TSS = 45% of the total budgeted costs for operating and maintaining the wastewater treatment facilities divided by total pounds TSS treated, current cost factor is $0.2640 per pound.
Surcharge = Surcharge computed in dollars as follows:
BOD5 Surcharge = V x (B-C) x 8.34 x Cost Factor BOD
TSS Surcharge = V x (B-C) x 8.34 x Cost Factor TSS
B = Total contribution from user in mg/L
C = Normal domestic sewage strength of 250 mg/L
8.34 = pounds per gallon (conversion)