The HRSD high strength waste surcharge categories are based on North American Industry Classification System (NAICS) industry groupings. The average concentrations are calculated from sampling and analysis of wastewater discharged from similar businesses located in the HRSD Service Area.
The current business categories and average wastewater concentrations are shown below:
All HRSD wastewater treatment charges are based on your actual water usage and the BOD, TSS, TP, and TKN average concentrations for your classification of business. The high strength waste surcharge rates and domestic quality wastewater thresholds may be found in the current HRSD Rate Schedule.
WHY ARE SURCHARGES ASSESSED TO CERTAIN BUSINESSES?
Some classifications of business are known to be capable of discharging high strength wastes [Biochemical Oxygen Demand (BOD), Total Suspended Solids (TSS), Total Phosphorus (TP), and Total Kjeldahl Nitrogen (TKN)] into the sewerage system. These classifications of business are sampled and tested by HRSD to determine average BOD, TSS, TP and TKN concentrations and whether a high strength waste surcharge is warranted.
HOW DOES HRSD DETERMINE AVERAGE WASTEWATER CONCENTRATIONS?
The testing is accomplished by temporarily installing an automatic sampling device to sample only that wastewater discharged by certain classifications of business. Multiple facilities from each classification of business are sampled for a full business week with the sampler being serviced daily. Results from the sampling are compiled to determine average surcharge concentrations for each classification of business. If the average surcharge concentrations are above the domestic quality wastewater threshold for any parameter, then a high strength waste surcharge is applicable.
WHAT ARE SOME OF THE CAUSES OF HIGHER WASTEWATER CONCENTRATIONS?
Discharge of food solids, animal and vegetable fats, oils and greases and cleaning chemicals can all increase BOD, TSS, TP, and TKN concentrations. Improper maintenance of grease control devices or not having a grease control device may also result in higher strength wastes. In addition, the use of garbage grinders may increase wastewater strength.
For questions regarding surcharge billing, contact our Billing Coordinator at 757.460.7053 or firstname.lastname@example.org.