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PART III <br />Page 44 of 47 <br />Permit No.:0O0000213 <br />APPENDIX B - Definitions <br />1. "Acute Toxicity" - The acute toxicity limitation is exceeded if the LC50 is at any effluent concentration less than or equal to the <br />IWC indicated in this permit. <br />2. "Best Management Practices (BMPs)" - schedules of activities, practices (and prohibitions of practices), structures, vegetation, <br />maintenance procedures, and other management practices to prevent or reduce the discharge of pollutants to state waters. <br />BMPs also include treatment requirements, operating procedures, and practices to control plant site runoff, spillage or leaks, <br />sludge or waste disposal, or drainage from raw material storage. See 5 CCR 1002-61.2(9). <br />3. "Chronic toxicity", which includes lethality and growth or reproduction, occurs when the NOEC and IC25 are at an effluent <br />concentration less than the IWC indicated in this permit. <br />4. "Composite" sample is a minimum of four (4) grab samples collected at equally spaced two (2) hour intervals and proportioned <br />according to flow. For a SBR type treatment system, a composite sample is defined as sampling equal aliquots during the <br />beginning, middle and end of a decant period, for two consecutive periods during a day (if possible). <br />5. "Continuous" measurement, is a measurement obtained from an automatic recording device which continually measures the <br />effluent for the parameter in question, or that provides measurements at specified intervals. <br />6. "Control Measure" refers to any BMP or other method (including effluent limitations) used to prevent or reduce the discharge <br />of pollutants to waters of the state. <br />7. "Daily Maximum limitation" for all parameters (except temperature, pH and dissolved oxygen) means the limitation for this <br />parameter shall be applied as an average of all samples collected in one calendar day. For these parameters the DMR shall <br />include the highest of the daily averages. For pH and dissolved oxygen, this means an instantaneous maximum (and/or <br />instantaneous minimum) value. The instantaneous value is defined as the analytical result of any individual sample. For pH and <br />dissolved oxygen, DMRs shall include the maximum (and/or minimum) of all instantaneous values within the calendar month. <br />Any value beyond the noted daily maximum limitation for the indicated parameter shall be considered a violation of this permit. <br />8. "Discharge" - when used without qualification, means the "discharge of a pollutant." See 5 CCR 1002-61.2(22). <br />9. "Discharge of a pollutant" - the introduction or addition of a pollutant into state waters. See 25-8-103(3) C.R.S. <br />10. "Dissolved (D) metals fraction" is defined in the Basic Standards and Methodologies for Surface Water 1002-31, as that portion <br />of a water and suspended sediment sample which passed through a 0.40 or 0.45 UM (micron) membrane filter. Determinations <br />of "dissolved" constituents are made using the filtrate. This may include some very small (colloidal) suspended particles which <br />passed through the membrane filter as well as the amount of substance present in true chemical solution. <br />11. "Good Engineering, Hydrologic and Pollution Control Practices" - methods, procedures, and practices that a) are based on basic <br />scientific fact(s); b) reflect best industry practices and standards; c) are appropriate for the conditions and pollutant sources; <br />and d) provide appropriate solutions to meet the associated permit requirements, including all effluent limitations. <br />12. "Grab" sample, is a single "dip and take" sample so as to be representative of the parameter being monitored. <br />13. "IC25" or "Inhibition Concentration" is a point estimate of the toxicant concentration that would cause a given percent <br />reduction in a non -lethal biological measurement (e.g. growth or reproduction) calculated from a continuous model (i.e. <br />interpolation method). IC25 is a point estimate of the toxic concentration that would cause a 25 -percent reduction in a non- <br />lethal biological measurement. <br />14. "Industrial Activity" - the 10 categories of industrial activities included in the definition of "stormwater discharges associated <br />with industrial activity" as defined in 5 CCR 1002-61.3(2). <br />15. "Industrial Stormwater" - stormwater runoff from industrial activity. <br />16. "In-situ" measurement is defined as a single reading, observation or measurement taken in the field at the point of discharge. <br />