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01319 Manganese, potentially dissolvd 1 - Effluent Gross 0 -- <br />Sample =170 =187 28 - ug/L <br />0 <br />02/30 - Twice Per Month GR - GRAB <br />Permit Req. Req Mon 30DA AVG Req Mon DAILY MX 28 - ug/L 02/30 - Twice Per Month GR - GRAB <br />Value NODI <br />01323 Selenium, potentially dissolvd 1 - Effluent Gross 0 -- <br />Sample =1 =2 28 - ug/L <br />0 <br />02/30 - Twice Per Month GR - GRAB <br />Permit Req. Req Mon 30DA AVG Req Mon DAILY MX 28 - ug/L 02/30 - Twice Per Month GR - GRAB <br />Value NODI <br />03582 Oil and grease 1 - Effluent Gross 0 -- <br />Sample <br /> <br /> <br />Permit Req. <=10 INST MAX 19 - mg/L 77/77 - Contingent GR - GRAB <br />Value NODI 9 - Conditional Monitoring - Not Required This Period <br />04262 Chromium, trivalent total recoverable 1 - Effluent Gross 0 -- <br />Sample <20 <20 28 - ug/L <br />0 <br />02/30 - Twice Per Month GR - GRAB <br />Permit Req. Req Mon 30DA AVG Req Mon DAILY MX 28 - ug/L 02/30 - Twice Per Month GR - GRAB <br />Value NODI <br />50050 Flow, in conduit or thru treatment plant 1 - Effluent Gross 0 -- <br />Sample =0.776 =1.37 03 - MGD <br />0 <br />02/30 - Twice Per Month IN - INSTAN <br />Permit Req.<=1.5 30DA AVG Req Mon DAILY MX 03 - MGD 01/30 - Monthly IN - INSTAN <br />Value NODI <br />50286 Mercury, total [low level]1 - Effluent Gross 0 -- <br />Sample =0.0079 28 - ug/L <br />0 <br />02/30 - Twice Per Month GR - GRAB <br />Permit Req. Req Mon 30DA AVG 28 - ug/L 02/30 - Twice Per Month GR - GRAB <br />Value NODI <br />84066 Oil and grease visual 1 - Effluent Gross 0 -- <br />Sample =0 AB - abst=0;prst=1 <br />0 <br />02/30 - Twice Per Month VI - VISUAL <br />Permit Req. Req Mon INST MAX AB - abst=0;prst=1 01/30 - Monthly VI - VISUAL <br />Value NODI <br />Submission Note <br />If a parameter row does not contain any values for the Sample nor Effluent Trading, then none of the following fields will be submitted for that row: Units, Number of Excursions, Frequency of Analysis, and Sample Type. <br />Edit Check Errors <br />No errors. <br />Comments <br />Based on the enclosed information on precipitation/snowmelt events preceding the discharge of 3/27/2019, Tri-State requests determination that the alternate limitations for "precipitation less than or equal to the 10yr, 24hr storm event (or snowmelt of equivalent volume)" apply to the discharge at this <br />location, per Part I.1.C.1.b and page 12 of the permit. Blizzard conditions in mid-March led to heavy snow accumulation, and subsequent warm temperatures in late March resulted in high volumes of snowmelt (as recorded in the attached graph of precipitation and temperature for March). This pond was <br />properly operated and maintained prior to and during the storm event and subsequent snowmelt (based on routine pond inspections, as required by Part I.B.1 (Facilities Operation and Maintenance)). The measured flow during this snowmelt sample event was nearly 8X higher than the measured flow from <br />approximately three weeks earlier (0.181 MGD on March 6, 2019, compared to 1.370 MGD on March 27, 2019). Based on flow data, visual observations, and increased daily air temperatures in late March, the March 27, 2019 sample was collected during pond inflow from the snowmelt event. Therefore, <br />the ELG-based Total Iron effluent limits do not apply to the discharge on 3/27/2019. The 3/27/2019 sample contained 2730 mg/L Total Iron, and the monthly average (two samples) for Total Iron was 1415 mg/L. <br />Attachments <br />Name Type Size <br />Colowyo_March_2019_Temp_Precip_data.pdf pdf 207963 <br />Report Last Saved By <br />Colowyo Coal Co LP <br />User:dcrosby@tristategt.org <br />Name:Darlene Crosby <br />E-Mail:dcrosby@tristategt.org <br />Date/Time:2019-04-23 11:52 (Time Zone: -06:00) <br />Report Last Signed By <br />User:BARBARAWALZ1 <br />Name:Barbara Walz <br />E-Mail:bwalz@tristategt.org <br />Date/Time:2019-04-23 14:09 (Time Zone: -06:00)