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Part I Page No. 4 Permit No.: CO-0046348 TERMS AND CONDITIONS c, CtnrTn Fxemi lion Frnm Federal Ffflnent T.imitatinns - Clntfall OOSR (continued) All data/documentation required by this section which can not be reported on applicable dischazge monitoring report forms (DMRs) shall be reported in a letter as an attachment to the DMR. Submittal of documentation of containment, maintenance, and precipitation records above does not exetnpt the permittee from any other notification requirements of this permit. Before an overflow of the VLF occurs, CC&V shall implement one or both of the following means to route the discharge to Outfall OOSB. There will be a controlled release of flow from the External Storage Pond ("ESP") to Arequa Gulch. The 20 million gallon capacity ESP will have a system for reducing weak acid dissociable cyanide ("CNw,~') concentrations prior to release. Transfer of water from the ESP to Arequa Gulch will be accomplished using the pumpback pipeline. The sump for the pumpback will be used to direct flows from the pipeline into Arequa Gulch at OOSB, as shown in Figure 4 of the Permit. Only minor changes (e.g., removal of check valves, disconnection of pumps) to the pumpback system will be allowed to accommodate flows from the ESP. An alternative to the pumpback system will involve laying a temporary pipeline from the VLF over the Phase II toe berm to Arequa Gulch. Due to elevation change from the crest to the base of the toe berm, siphoning and gravity flow is possible. Existing riprap, geotextile, or liner material already in the area would be used alone or in combination to dissipate energy at the outlet of the pipe. Flows under either alternative would enter one of the BMPs in the uppermost reaches of Arequa Gulch before passing through Outfall OOSB, which is below Outfa11001A. d. Limits for Specific Outfalls Limits for Outfa11001A -Discharge From the Sediment Pond Located Below the Valley Leach Faciliri to Areaua Gulch as measured at AG-01.5 ~Dtschaz a Liirtttanons'' Effluent Parameter .30-Da ~Avera e ~` - ' ~ ~ Dail Max = ~ '^ ' Flow MGD Re ort Re ort TSS m /1 30 45 Oil and Grease m NV 10 Ammonia Total as N 200 Re ort Co er Potentiall Dissolved /I 29.3 49.6 Lead Potentiall Dissolved 1 Re ort Re ort Mercu Total I 0.01 Re ort Nickel Potentiall Dissolved I R ort Re ort C anide Free I 5* Re ort Aluminum Potentiall Dissolved 1 Re ort 11 000 Cadmium Potential] Dissolved 1 6.2 Re ort Iron Total Recoverable Re ort Re ort Man anese Potentiall Dissolved Throu h Janua 31 2003 Re ort Re ort Be 'nnin Febru 1 2003 3 674 5 905 Zinc Potentiall Dissolved 1 Throu h Janua 31 2003 Re ort** Re ort Be irutitt Febru 1 2003 600** Re ort Limits A licable Durhi Tem or Standazds Modifications -Effective Throu 12/31/07 H su minimum-maximum N/A 5.6-9.0 Limits Based U on Underl n Standards- Effective Be nnin 1/1/08 H su minimutn-maximum N/A 6.0-9.0 NV =None Visible. In the event an oil sheen or floating ail is observed, a grab sample shall be collected, analyzed, reported, and evaluated relative to the 10 mg/I daily maximum value. N/A =Not Applicable. * For cyanide, the standard for the receiving stream is based upon "free" cyanide concenvations, which is less than the "free" cyanide analytical detection limit. While the limit will be set equal to the seam standards, this permit allows zero to be used in the calculation of reporting values whenever an analytical result is less than the detection limit. As such, any "tree" cyanide concentrations Tess than the analytical detection limit will be considered to be zero. *" This limit is the 85th percentile value of the data collected at discharge point OOI A, for [he most recent 60 months including the month for which the discharge is being reported and calculated using the Microsoft Excel 85'" percentile function.