(A) Industrial Waste Surcharge Program

One element of industrial monitoring is the Surcharge Program. Surcharges apply to Biochemical Oxygen Demand (BOD) and Total Suspended Solids (TSS) for some facilities. Long term history, with analysis has established the levels of BOD and TSS in Amarillo domestic sewage. These levels are established at 300mg/L for BOD, and 400 mg/L for TSS. BOD and TSS are sampled at the industry and analyzed monthly by the city. This is then applied to the entire monthly flow for the industry, and calculations are made for charges applied to treating extra strength sewage. Note, in the following formula, domestic levels are subtracted. The industry, therefore, pays a surcharge only for the amounts above domestic levels.

The Surcharge Formula

S = Va(BOD-300) + Vb(TSS-400)

Where:

• S is the surcharge amount in dollars
• V is the monthly wastewater flow in Million gallons
• a is the unit cost for removing 1 mg/l of BOD from 1 million gallons ($1.4663)
• b is the unit cost for removing 1 mg/l of TSS from 1 million gallons ($0.6377)
• BOD is the actual BOD obtained from monthly sampling and analysis
• TSS is the actual TSS obtained from monthly sampling and analysis

Surcharges are not fines or penalties. Surcharges are intended to recoup the cost of treatment of extra strength wastes by the Publicly Owned Treatment Works (POTW). Surcharges must not be used to allow discharges of toxic pollutants that cause interference or pass through.

Example of Calculating Only A BOD Surcharge

BOD Portion

• The monthly BOD sample result is 1000 mg/l
• The industry used 5 million Gallons during the month
• (5 MG) x ($1.4663) x (1000 mg/l – 300 mg/l) = $5,132.05
• Surcharges, depending on permit requirements, can therefore be calculated for BOD, TSS, or both, as needed.

(B) Local Limits Program

Local Limits are pretreatment standards which are developed on a drainage basin basis. Amarillo has two drainage Basins: North for the River Road Wastewater Plant, and South for the Hollywood Road Wastewater Treatment Plant. Local Limits are developed based on how much of a specific pollutant a specific plant can remove from the influent. The influence on each plant is also composed of routine domestic sewage background levels of pollutants. These background levels are not part of the Local Limits for Industries, and calculation begins at any level above background. The amount of pollution above domestic background is called the Industrial Loading to the plant. The Significant Industrial Users within a given drainage basin, which discharge a specific pollutant, contribute to the industrial loading of that pollutant. Each Significant Industrial User is issued an Industrial Waste Permit, which is renewed every two years. The wastewater treatment plant routinely determines the efficiency and ability to remove the pollutant by what is known as a TCEQ required, Technically Based Local Limits Study (more commonly known as a TBLL study). The Significant Industrial Users within a drainage basin then share in a cumulative manner to the treatment plant loading of that parameter. The flow an industry contributes is important to the calculation process and is known as the Contributory Flow. The Significant Industrial Users are thereby “contributing” to the total loading and a local limit is calculated for that parameter. This creates a set of local limits for the River Road Basin, and a set of local limits for the Hollywood Road Basin. Each Significant Industrial User is sent a copy of the local limits for their Drainage Basin.

Calculating The Local Limit

• Local Limit = AIL ÷ (8.34 x Q)
• Local Limit – Permit Limit, mg/l
• AIL – Allowable Industrial Loading (total pounds of a pollutant from industrial input above background, allowed into the plant, as determined in the TBLL study)
• Q – Total Significant Industrial Flow which discharges the parameter above the “background level”, in MGD (million gallons per day).

The city samples for Local Limits twice a year. The following parameters are monitored as a part of the Local Limits sampling: Arsenic, Cadmium, Chromium, Copper, Cyanide, Lead, Mercury, Molybdenum, Nickel, Selenium, Silver, Zinc, Phenols