Res 2005-105 - Laserfiche WebLink

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City of San Marcos TPDES Permit No. WQOOl0273002 DEFINITIONS AND STANDARD PERMIT CONDITIONS \s required by Title 30 Texas Administrative Code (TAC) Chapter 305, certain regulations appear as standard conditions in waste lischarge permits. 30 TAC SS 305.121 - 305.129 (relating to Permit Characteristics and Conditions) as promulgated nnder the 'exas Water Code SS 5.103 and 5.105, and the Texas Health and Safety Code SS 361.017 and 361.024(a), establish the ~haracteristics and standards for waste discharge permits, including sewage sludge, and those sections of 40 Code of Federal Regulations (CFR) Part 122 adopted by reference by the Commission. The following text includes these conditions and incorporates them into this permit. All defmitions in Section 26.001 of the Texas Water Code and 30 TAC Chapter 305 shall apply to this permit and are incorporated by reference. Some specific definitions of words or phrases used in this permit are as follows: 1. Flow Measurements a. Annual average flow - the arithmetic average of all daily flow determinations taken within the preceding 12 consecutive calendar months. The alIDual average flow determination shall consist of daily flow volume detenninations made by a totalizing meter, charted on a chart recorder and limited to major domestic wastewater discharge facilities with a 1 million gallons per day or greater permitted flow. b. Daily average flow - the arithmetic average of all determinations of the daily flow within a period of one calendar month. The daily average flow determination shall consist of determinations made on at least four separate days. Ifinstantaneous measurements are used to determine the daily flow, the determination shall be the arithmetic average of all instantaneous measurements taken during that month. Daily average flow determination for intermittent discharges shall consist of a minimum of three flow determinations on days of discharge. c. Daily maximum flow - the highest total flow for any 24-hour period in a calendar month. d. Instantaneous flow - the measured flow during the minimum time required to interpret the flow measuring device. e. 2-hour peak flow (domestic wastewater treament plants) - the maximum flow sustained for a two-hour period during the period of daily discharge. The average of multiple measurements of instantaneous maximum flow within a two-hour period may be used to calculate the 2-hour peak flow. f. Maximum 2-hour peak flow (domestic wastewater treatment plants) - the highest 2- hour peak flow for any 24-hour period in a calender month. 2_ Concentration Measurements a. Dailyaverage concentration - the arithmetic average of all effluent samples, composite or grab as required by this permit, within a period of one calendar month, consisting of at least four separate representative measurements. L F or domestic wastewater treament plants - When four samples are not available in a calendar month, the arithmetic average (weighted by flow) of all values in the previous four consecutive month period consisting of at least four measurements shall be utilized as the daily average concentration. 11. For all other wastewater treament plants - When four samples are not available in a calender month, the arithmetic average (weighted by flow) of all values taken during the month shall be utilized as the daily average concentration. b. 7 -day average concentration - the arithmetic average of all efiluent samples, composite or grab as required by this permit, within a period of one calendar week, Snnday through Saturday. c. Daily maximum concentration - the maximum concentration measured on a single day, by the sample type specified in the pemrit, within a period of one calender month. d. Daily discharge - the discharge of a pollutant measured during a calendar day or any 24-hour period that reasonably represents the calendar day for purposes of sampling. For pollutants with limitations expressed in tenus of mass, the "daily discharge" is calculated as the total mass of the pollutant discharged over the sampling day. For pollutants with limitations expressed in other units of measurement, the "daily discharge" is calculated as the average measurement of the pollutant over the sampling day. The "daily discharge" determination of concentration made using a composite sample shall be the concentration of the composite sample. When grab samples are used, the "daily discharge" determination of concentration shall be the arithmetic average (weighted by flow value) of all samples collected during that day. Page 3