Laserfiche WebLink
COLORADO DEPARTMENT~F HEALTH, Water Quality Contro~ivision <br />Permit Number CO-0032751 Page 8 . <br />D. Whole Effluent Toxicity (WET) Testine: <br />For this facility, acute and chronic biomonitoring are required (See Parts <br />I.A.1, I.B.1, and I.B.3 through I.B.10 of the permit). Monitoring shall <br />be performed commencing with the first full calendar quarter following the <br />permit effective date. <br />Purpose of WET Testing: Section 6.9.7 of the Regulations for the State <br />Discharge Permit System (6.1.0), passed by the Water Quality Control <br />Commission (WQCC), has established the use of WET testing as a method for <br />identifying and controlling toxic discharges from wastewater treatment <br />facilities. WET' testing is being utilized as a means to ensure that there <br />are no discharges "in amounts, concentrations or combinations which are <br />harmful to the beneficial uses or tor:ic to humans, animals, plants, or <br />aquatic life" as required by Section 3.1.11 (1)(d) of the Basic Standards <br />and Methodologies. <br />Chemical analysis of effluent has provided only a partial evaluation of <br />the potential impact a discharge could have on the receiving stream. <br />Also, chemical analysis cannot evaluate the synergistic or antagonistic <br />effect of compounds. There are also compounds for which an accurate or <br />reproducable method of chemical analysis has not yet been developed, as <br />well as compounds which are just beginning to be evaluated for toxic <br />effects. WET testing will provide a more comprehensive means of <br />evaluating the toxicity of a discharge than could otherwise currently be <br />accomplished. <br />Instream Wastewater Concentration IWC): As a condition of the permit, <br />the permittee will be required to conduct routine monitoring for acute <br />toxicity. Acute toxicity occurs when there is a statistically significant <br />difference in the mortality observed, for Ceriodaohnia sp. (water flea) <br />and fathead minnows, between the control and any effluent concentration. <br />Should acute toxicity be detected in any effluent concentration less than <br />or equal to the Instream Wastewater (:oncentration (IWC) or should a <br />species mortality in any dilution of effluent (including 100X effluent) <br />exceed 50X, the permittee is required to conduct a series of timely tests <br />to identify and ultimately eliminate or treat the toxicant. The IWC. is <br />determined using the following equation: <br />IWC - jFacility Flow {FF)/(Strearu Low Flow (annual) + FF)] X 100X <br />Using the seasonal facility flow limits (0.036/0.122/0.093 MGD) and the <br />instream acute stream low flows for Coon Track Creek (lE3 - <br />0.026/0.071/0.39 MGD for the respective seasons of August-March, <br />April-June, and July), the three seasonal IWC values for the permittee are <br />therefore 58.1X, 63.2X, and 19.3X. :For the August through March season, <br />the 37.9X IWC value represents a wastewater concentration of 58.1X <br />effluent to 41.9X dilution water. <br /> <br />Chronic Biomonitorine: The det:ermin.ation as to whether or not an <br />individual facility must conduct chronic WET testing is dependent upon the <br />type of facility discharge and the classification of the recieving <br />