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Appendix 4.7-8 <br />PART III <br />Page 28 of 31 <br />Permit No.: C00048972 <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 <br />equal to the IWC indicated in this permit. <br />2. 'Best Management Practices (BMPs)" - schedules of activities, practices (and prohibitions of practices), structures, <br />vegetation, maintenance procedures, and other management practices to prevent or reduce the discharge of <br />pollutants to state waters. BMPs also include treatment requirements, operating procedures, and practices to <br />control plant site runoff, spillage or leaks, sludge or waste disposal, or drainage from raw material storage. See 5 <br />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 <br />effluent 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 <br />proportioned according to flow. For a SBR type treatment system, a composite sample is defined as sampling equal <br />aliquots during the beginning, middle and end of a decant period, for two consecutive periods during a day (if <br />possible). <br />5. "Continuous" measurement, is a measurement obtained from an automatic recording device which continually <br />measures the 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 <br />discharge of pollutants to waters of the state. <br />7. "Daily Maximum limitation" for all parameters (except temperature, pH and dissolved oxygen) means the limitation <br />for this parameter shall be applied as an average of all samples collected in one calendar day. For these <br />parameters the DMR shall include the highest of the daily averages. For pH and dissolved oxygen, this means an <br />instantaneous maximum (and/or instantaneous minimum) value. The instantaneous value is defined as the <br />analytical result of any individual sample. For pH and dissolved oxygen, DMRs shall include the maximum (and/or <br />minimum) of all instantaneous values within the calendar month. Any value beyond the noted daily maximum <br />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 <br />that portion of a water and suspended sediment sample which passed through a 0.40 or 0.45 UM (micron) <br />membrane filter. Determinations of "dissolved" constituents are made using the filtrate. This may include some <br />very small (colloidal) suspended particles which passed through the membrane filter as well as the amount of <br />substance present in true chemical solution. <br />11. "Good Engineering, Hydrologic and Pollution Control Practices" - methods, procedures, and practices that a) are <br />based on basic scientific fact(s); b) reflect best industry practices and standards; c) are appropriate for the <br />conditions and pollutant sources; and d) provide appropriate solutions to meet the associated permit requirements, <br />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 <br />percent reduction in a non -lethal biological measurement (e.g. growth or reproduction) calculated from a <br />continuous model (i.e. interpolation method). IC25 is a point estimate of the toxic concentration that would cause <br />a 25 -percent reduction in a non -lethal biological measurement. <br />14. "Industrial Activity" - the 10 categories of industrial activities included in the definition of "stormwater discharges <br />associated with industrial activity" as defined in 5 CCR 1002-61.3(2). <br />15. "Industrial Stormwater" - stormwater runoff from industrial activity. <br />