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2009-03-06_PERMIT FILE - C1981012A (6)
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2009-03-06_PERMIT FILE - C1981012A (6)
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Last modified
7/11/2017 9:39:10 AM
Creation date
8/4/2009 11:01:08 AM
Metadata
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Template:
DRMS Permit Index
Permit No
C1981012A
IBM Index Class Name
Permit File
Doc Date
3/6/2009
Section_Exhibit Name
Exhibit 22 NPDES Permit
Media Type
D
Archive
Yes
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COLORADO DEPARTMENT OF PUBLIC HEALTH AND ENVIRONMENT, Water Quality Control Division <br />Rationale -Page 17, Permit No. CO-0000906 <br />which are to be reported as an LC50., which is the concentration at which 50"x, or more of the organisms die. If <br />• the LC50 occurs in a concentration of less than or equal to 100% effluent, the permittee is required to comply <br />with the specifications identified in Part I.A.S. of the permit. <br />v. General Information - The permittee should read the WET testing section of Parts I.A.4. anti I.A.S. of the permit <br />carefully. The permit outlines the test requirements and the required follow-up actions the permittee must take <br />to resolve a toxicity incident. The permittee should read, along with the documents listed in Parts I.A. 4. and <br />1.A.5. of the permit, the Colorado Water uali Control Division Biomonitorin Guidance Document dated <br />July 1, 1993. This document outlines the criteria used by the Division in such areas as granting relief from <br />WET testing, modifying test methods and changing test species. The permittee should be aware that some of the <br />conditions outlined above may be subject to change if the facility experiences a change in discharge, as outlined <br />in Part II.A.2. of the permit. Such changes shall be reported to the Division immediately. <br />3. Discussion of Effluent Limitations for Groundwater Discharges <br />Based on available information provided by DRMS concerning the construction of the ponds, the Division has concluded <br />that Pond 6 will not meet the allowable seepage rate. Thus, this permit establishes limits for the protection of <br />groundwater standards. However, the Division is still requiring the conduct of a study (and submittal of a report) to <br />conclusively determine if the allowable seepage rate can be met (see the compliance schedule set forth in later <br />subsections). <br />If the facility determines that Pond 6 does not exceed the allowable seepage rate of I x 10"6 cm/sec, groundwater <br />protection requirements will not apply and the facility must submit a request for a permit modification to delete the <br />limitations and other permit requirements pertaining to the protection of groundwater. However, if the allowable <br />seepage rate is exceeded, the facility may either line Pond 6 with a synthetic liner that would prevent discharges to <br />groundwater in excess of '1 x 10-6 cm/sec or develop a groundwater protection program. <br />If the facility elects to synthetically line Pond 6 in accordance with proper engineering procedures, the facility will be <br />considered not to have a discharge to waters of the state in accordance with Section 61.14(9)(a) of the Colorado <br />Discharze Permit System Regulations. In this scenario, the permittee must submit a request for a permit modification to <br />delete the limitations and other permit requirements pertaining to the protection of groundwater. <br />However, if Pond 6 is discharging at greater than the allowable seepage rate of'] x 10"6 cm/sec and the facility opts <br />NOT to synthetically line Pond 6, the permittee must implement a groundwater protection program. In this scenario, <br />Regulation 62 limitations for BOD & TSS must be met at Outfal1033 in order for groundwater discharges to be <br />compliant with the regulations and the facility must determine the point of compliance for the groundwater standards via <br />one of two options: (1) at the influent to Pond 6; or (2) in downgradient groundwater monitoring wells. <br />The Division has developed this permit expecting that seepage will exceed the allowable seepage rate, that the facility <br />will decide not to line Pond 6, and that the facility will select the point of compliance as the groundwater alluvium. <br />Based on this assumption, the Division has developed the limits contained in Table VI-5 through VI-7. The applicable <br />limitations at Outfall 033 and the limitations to protect groundwater standards at the selected point of compliance are <br />set forth in the paragraphs that follow. If the permittee opts differently, a modification to this permit must be requested. <br />a. BODs TSS Oil & Grease pH and Total Residual Chlorine - The Regulations for Effluent Limitations (Regulation <br />No. 62) include effluent limitations that apply where the Division identifies the pollutant as one that may, without <br />treatment, be present in the discharge at a level approaching the relevant limit. Further, the State's effluent <br />limitations in Regulation 62, Regulations for Effluent Limitations, must be met prior to dilution with other waters <br />including groundwater. Therefore, at Internal Outfall 033 and prior to entering Pond 6, the effluent limitations for <br />some of these parameters are being established as limits. <br />effluent <br />The pH, BOD5 and TSS concentrations from the Regulations for Effluent Limitations are the most stringent <br />limits and are therefore applied. The removal percentage for BOD5 and TSS also apply based on the Regulations <br />for Effluent Limitations. Because influent monitoring must be conducted in order to calculate removal percentages, <br />• the Division has established an influent monitoring outfall 3001 to conduct influent BOD5 and TSS monitoring. <br />These limitations are incorporated with a delayed effective date to ensure that the limitations actually apply based <br />on the findings of the seepage rate study and decisions to continue to discharge to groundwater. In the interim, <br />monitoring for these parameters will be established consistent with the previous permit.
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