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COLORADO DEPARTMENT OF PUBLIC HEALTH AND ENVIRONMENT, Water Qualiry Conrrof Div[sion
<br />Rationale -, Page 3, Permit Na. CO-004516] _
<br />B. Wastewater Treatment Description
<br />All wastewater ultimately discharged will, at a minimum, be treated through sedimentattars ponds. This primarily includes
<br />surface runoff, but also includes the potential for discharge of other sources as described below. All discharges may be
<br />intermittent.
<br />The non-surface runoffsources also indudegood quality groundwater ofunknown on'gin thatJlows to the Streeter Pond (outfall
<br />OOIA). In addition, outfa11008A may contain water from two natural springgs and underdrain water with flows ofless than 7gpm
<br />from a system installe as part ofthe West Pit Fill construction. Outja lOlOA may also contain underdrain water and possibly ai
<br />a future nme, spoils spring water.
<br />In addition, the permittee wants the option to discharge vehicle wash water that can be controlled and then discharged ij
<br />necessary. This wash water has the potential to contain coal dust, oil and other petroleum products. The water flows to the
<br />Washbay Pond, a normally nondtscharging pond. Ifthe Washbay Pond fills, tt may be necessary to transfer the water to the Work
<br />Area Pond (002A), from whtch discharge may occur to Taylor Creek (see the permit, Figure 3). This would happen infrequently.
<br />The permittee has also indicated [hat they would like to use the water from any ofthe outfalls for dust suppression. They would
<br />apply the water at levels that would not result in runoff.
<br />During the previous permit renewal period, the permittee reevaluated all the ponds, using the CDMG-approved SEDCAD
<br />hydro[o~ model, far conversion to the "treatment"mode, wherein discharge occurs automatically when the volume reaches a
<br />certain level. Primary discharge structures consist of perforated riser pipes; secondary/ emergency spillways consist of o en
<br />channels near the top of the ponds. All ponds can maintaen a 'permanent ppool " of water that remains below the level o~he
<br />perforated riserpipe unless the lowergate:s manually opened to release tt. Asflow comes into the pond, it displaces the water in
<br />thepermanentpool. Typically,aprimaryspillwaywilladequatelydtschargemostflows; secondary spillways serve to discharge
<br />largerflows due to rainfall or snowmelt equivalent to the 255-yyear, 24-hour event orgreater. When the incomingflows are within
<br />the range treatable by theponds, the effluent quality should be within the discharge standards, providing theponds areproperly
<br />maintained and operated. Colowyo worked with the CDMG to receive approval to make this c tinge. All changes to pond design
<br />or factors affecting the pond inflow or outflow are reviewed and approved by the CDMG before implementation. Table IV-2,
<br />preceding, shows data related to all outfa is authorized under this permit
<br />of Article 9, Title 25,
<br />73istribution Systems; Juan Garcia, Class "'L
<br />Scott, Class ' D"Industrial Wastewater (#1
<br />. V PERFORMANCE HISTORY
<br />A. Monitoring Data
<br />1. Dischar a Monitorin Re orts: Tables V-1 through V-7 summarize the a uent data reported on the qquarterly Discharge
<br />Monitoring Reports tt 's) or theColowyofacilityfromSeptemberl9 9throughMarch2004 orOutfal1s001A, 002A,
<br />OOZB, 003A, 004A, OSA, and 006A. The permittee reported "no dt'scharge"during this period for Outfalls 004$ 007A
<br />through OIOB. Internal ou~(tills with the designation B,"were removed as a monitoring requirement, because the
<br />permittee has demonstrated that monitoring at the external outfalls was sufficient to meet the applicable effluent limitations,
<br />Table V-1 -- Self-Monitoring Results for Outfal1001A
<br />
<br />
<br />Parameter No. of Reporting ReportedConcentrarions
<br />revious
<br />Permit
<br />o. o
<br />Limitation
<br /> periods Avg/Min/Max
<br />- Limitation Excursions
<br />ow,
<br />30-day avg ]8 0.094/0.023/0.16 Report NA
<br />Dail max 18 0.[58/0.032/0.65 Re ort NA
<br />m
<br />30 day avg 18 11.9/0.0/23 35 0
<br />Dail max IB 12.9/0.0/28 70 0
<br />i rease, mg
<br />30-day avg 18 NV/NV/NV Report NA
<br />Dail max 18 NV/NV/NV 10 0
<br />s. u. mi max 1 - .97 6. - .0
<br />Sett ea e o i s, m ,
<br />30-day avg 18 0.0/0.0/0.1 Report NA
<br />Dail max 18 0.0/0.0/0.1 0.3 0
<br />TD,m
<br />30-day avg 18 1,675/0.13/2,200 Report NA
<br />Dail max 18 1,687/0.13/2200 Re ort NA
<br />Tota Iron, m
<br />30-day avg l8 0.22/0.04/0.53 3.5 0
<br />Dail max 18 0.23/0.04/0.53 7.0 0
<br />•
<br />Revised 7/24/2005
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