MSD has a Quality Charge Testing (QCT) program in place for the purpose of billing industrial and commercial users proportionally for wastewater strengths or concentrations that exceed established allowances. The pollutants currently used by MSD to assess billing rates are Biochemical Oxygen Demand (BOD) and Total Suspended Solids (TSS). The current allowances for BOD and TSS are 250 milligrams/liter and 270 milligrams/liter, respectively. Average BOD and TSS concentrations are computed using MSD laboratory analysis results from MSD sampling activity at each users facility. MSD sampling activity consists of obtaining the most representative sample possible of the wastewater discharged by the user. This includes obtaining accurate flow measurement via Louisville Water Company water meter readings and/or private meter readings (subtractor and/or add on meters owned by the user and certified by MSD).
The two most common questions asked about quality charges concern the computations used to derive the average BOD and TSS concentrations used to assess the billing rate and the calculation of the billing rates. Average BOD and TSS concentrations are determined using a flow weighted average. The current billing rate factors used by MSD are: BOD - $0.003015 per mg/l per 1000 gallons (in excess of 250 mg/l) and TSS - $0.00124243 per mg/l per 1000 gallons (in excess of 270 mg/l). Below is an example calculation based on a two day QCT survey. Quality Charge Program questions should be directed to Lisa A. Gaus at (502) 540-6910.
Average BOD And TSS Concentration Calculations
Therefore, the average BOD and TSS results for this user are:
BOD = 343 mg/l and TSS = 307 mg/l
Billing Rate Calculation
*mg/l = milligrams per liter
August 14, 2013