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COLORADO DEPARTMENT OF PUBLIC HEALTH AND ENVIRONMENT, Water Quality Control Division
<br />Rationale - Page 18, Permit No. CO-0000906
<br />In accordance with footnotes 5 and 6 in Section 62.5(1) of the Regulations for Effluent Limitations, the total restual
<br />• chlorine and Oil & Grease limitations do not apply to discharges to groundwater.
<br />Although the BODS and TSS limitations were not imposed at internal Outfall 033 in the previous permit, these limits
<br />are imposed in this permit consistent with State regulations.
<br />b. Limitations Based on Groundwater Standards - Based on the compliance schedule set forth in later subsections, a
<br />groundwater protection program is also being implemented. The schedule provides the facility with a staggered
<br />implementation of monitoring to ensure that the facility has time to decide on a plan of action and to install
<br />monitoring wells if such an option is selected.
<br />limitations to give the facility time ?o determine compliance s?ategeesess for the
<br />ground water standards as permit
<br />Although the facility has not yet determined the appropriate number of monitoring wells, general Division
<br />procedure is to accommodate at least one upgradient monitoring well (Outfall 050A) and three downgradient
<br />monitoring wells (Outfalls 050B, 050C and 050D) and therefore these outfalls are specified in Tables VI-6 and VI-7.
<br />i. pH - This parameter is placed in the permit to protect ground water standards for pH, which are found in
<br />Regulation 41, The Basic Standards for Ground Water.
<br />Limits of'6.5 su, instantaneous minimum, to 8.5 su, instantaneous maximum, are imposed at the downgradient
<br />groundwater monitoring wells 0508, 050C and 050D, with an appropriate effective date for the limits and
<br />monitoring, only, required prior to the limits' effective date. Monitoring, only, is also required at the
<br />upgradient groundwater monitoring well 050A. Note that monitoring requirements become effective in
<br />accordance with the compliance schedule allowing time for monitoring well installation or modifications to the
<br />permit, as appropriate.
<br />ii. Total Coli or m - Total coliform limits are placed in the permit to protect ground water quality standards for
<br />i this parameter found in Regulation 41, The Basic Standards for Ground Water. The total coliform standards
<br />are established depending on the method of analysis. The permittee would be required to select either of the
<br />following two analytical methods: (1) Membrane Filter Technique (MFT), Method 92228, which is found in the
<br />Standard Methods for the Examination of Water and Wastewater); (2) the Multiple Tube Fermentation
<br />Technique (MTFT), Method 9221B, which is also found in Standard Methods).
<br />The daily maximum of 23 colonies/100 ml (either method) and the 30-day average total coliform limit of 2.2
<br />colonies/100 ml (MTFT) are imposed at the downgradient groundwater monitoring wells 050B, 050C and
<br />050D, with an appropriate effective date for the limits and monitoring, only, required prior to the limits'
<br />effective date. Monitoring, only, is also required at the upgradient groundwater monitoring well 050A. Note
<br />that monitoring requirements become effective in accordance with the compliance schedule allowing time for
<br />monitoring well installation or modifications to the permit, as appropriate.
<br />If the permittee decides to change to the other method of analysis, the permittee must request an amendment to
<br />this permit,
<br />iii. Dissolved Nitrate plus Nitrite - The dissolved nitrate plus nitrite limit is placed in the permit to protect the
<br />ground water standard for nitrate plus nitrite found in Regulation 41, The Basic Standards for Ground Water.
<br />A limit of 10 mg1l (30-day average) is imposed at the downgradient groundwater monitoring wells 050B, 050C
<br />and 050D, with an appropriate effective date for the limits and monitoring, only, required prior to the limits'
<br />effective date. Monitoring, only, is also required at the upgradient groundwater monitoring well 050A. Note
<br />that monitoring requirements become effective in accordance with the compliance schedule allowing time for
<br />monitoring well installation or modifications to the permit, as appropriate.
<br />iv. Dissolved Chloride and Dissolved Sulfate - The dissolved chloride and dissolved sulfate limits are placed in the
<br />permit to protect these particular groundwater- standards found in Regulation 41, The Basic Standards for
<br />• Ground Water.
<br />Dissolved chloride and dissolved sulfate limits both of 250 mg1l (30-day average) are imposed at the
<br />downgradient groundwater monitoring wells 050B, 050C and 050D, with an appropriate effective date for the
<br />limits and monitoring, only, required prior to the limits' effective date. Monitoring, only, is also required at the
<br />upgradient groundwater monitoring well 050A. Note that monitoring requirements become effective in
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