Laserfiche WebLink
Minrec, Incorporated Water Quality Assessment <br />CO- 0048233 <br />data exists to define the mean hardness value at the periodic low flow criteria, representative <br />regional data shall be used to perform the regression analysis. Where a regression analysis is <br />not appropriate, a site - specific method should be used. <br />In the absence of specific hardness data for North Thompson Creek, hardness values were calculated from <br />calcium and magnesium provided by the permittee and used in a previous WQA. This data was collected <br />from North Thompson Creek, downstream of the discharge during the period 1995 through 2000. <br />Hardness was calculated using the following formula recognized by the Division: <br />Hardness (mg /l) 2.497 X Ca (in mg1l) + 4.116 X Mg (in mg1l) <br />The hardness was computed to be 133 mg /1. This hardness value and the formulas contained in the TVS <br />were used to calculate the in- stream water quality standards for metals, with the results shown in Table A- <br />4. <br />Table A -4 <br />TVS -Based Metals Water Quality Standards for CO- 047694 <br />Based on the Table Value Standards Contained in the Colorado Department of Public Health and <br />Environment Water Quality Control Commission Regulation 33 <br />Parameter <br />In- Stream Water <br />Quality Standard <br />TVS Formula: <br />Hardness (mg/l) as CaCO3 = 133 <br />Cadmilull, Dissolved <br />Acute <br />2.2 pg/l <br />[1. 136672- 0.0418381n( hardness )]e(0.9151(ln(hardness)) - 3.6236) <br />Chronic <br />0.53 pg/l <br />[1.101672-0.0418381n(hardness)le (0.7998(ln(hardness))- 4.4451) <br />Hexavalent Chromium, <br />Dissolved <br />Acute <br />16 W <br />Numeric standards provided, formula not applicable <br />Chronic <br />I I W <br />Numeric standards provided, formula not applicable <br />Copper, Dissolved <br />Acute <br />18 WA <br />e (0.9422(ln(hardness))- 1.7408) <br />Chronic <br />I I WA <br />e (0.8545(ln(hardness))- 1.7428) <br />Lead, Dissolved <br />Acute <br />88 po <br />(1.273(ln( hardness))- 1.46)] <br />[1.46203- 0.1457121n(hardness)][e <br />Chronic <br />3.4 po <br />[1.46203- 0.1457121n(hardness)] [e (1.273(ln(hardness))- 4.705)] <br />Manganese, Dissolved <br />Acute <br />3283 po <br />e (0.333 1 (ln(hardness))+6.4676) <br />ChrOffiC <br />1814 W/l <br />e (0.333 1 (ln(hardness))+5.8743) <br />Nickel, Dissolved <br />Acute <br />596 WA <br />e (0.846(ln(hardness)) +2.253) <br />Chronic <br />66 WA <br />e (0.846(ln(hardness)) +0.0554) <br />Selenium, Dissolved <br />Acute <br />18.4 WA <br />Numeric standards provided, formula not applicable <br />Chronic <br />,,�n <br />4.6 l am' 1 <br />Numeric standards provided, formula not applicable <br />Silver, Dissolved <br />Acute <br />3.3 WA <br />12 e (1.72(ln(hardness)) -6.52) <br />Chronic <br />0.12 WA <br />e (1.72(ln(hardness))- 10.5 1) <br />Zinc, Dissolved <br />Acute <br />183 µg/1 <br />0.978e (0.8525(ln(hardness)) +1.0617) <br />Chronic <br />159 µg/1 <br />0.986 e (0.8525(ln(hardness)) +0.9109) <br />Appendix A (wQA v 7.0) Page 8 of 25 Last Revised Sept 14, 2009 /ES <br />