(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 influent to 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