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.e <br />-13- <br />Water quality data on Del Rgua Canyon drainage is limited. However, some <br />observations are clear. The major ionic character of the water is calcium bi- <br />carbonate, which is similar in quality to alluvial monitoring data collected at <br />the mine. Trace element and heavy metal concentrations are below suspect ZeveZs <br />and criteria and do not appear to increase substantially due to the operation. <br />Suspended solids concentration can be several hundred milligrams per litre, which <br />is not abnormal in this type of environment. The concentration, however, does not <br />appear to increase appreciably due to mining activities. This might indicate <br />that the sediment control system at the mine is effective in controlling sediment. <br />The sediment control system at the mine is designed to collect runoff from all <br />affected areas and reduce suspended solids concentration to an acceptable level. <br />This practice will prevent sediment from the mine from reaching the receiving <br />stream and will thereby reduce sediment-related impacts. Sediment may impact the <br />environment under uncontrolled conditions by degrading aquatic habitats, carrying <br />other pollutants, devaluing property, posing a maintenance problem for downstream <br />irrigation users, increasing downstream mater treatment costs, reducing stream <br />channel capacity, and altering the floodplain. <br />The applicant has designed the sediment r_ontrol system utilizing the design and <br />performance standards of Raze 4.05 and best engineering practices. A discussion <br />of the design, construction, and reclamation of the system is found in Volume I, <br />Sections 5.3.2.2, 5,3.9, and 7.9,1. Design calculations are found in Volume I, <br />Exhibit V-3,, Volume III, pages 68-7Z, ancf Volume IV, Hydrology. No variances from <br />any of the requirements of Rule 9.05 were requested by the applicant, and only one <br />concern was raised that was not resolved during the review process. The following <br />stipulation is, therefore, required: <br />Stipulation No. 2: <br />WITHIN 120 DRYS AFTER PERf4IT ISSUANCE, ALL SEDIFfENTATION PONDS <br />SHALL BE CERTIFIED BY A QUALIFIED REGISTERED PROFESSIONAL ENGINEER. <br />THE CERTIFIED REPORT SRALL STATE 'THAT THE PONDS WERE CONSTRUCTED <br />IN ACCORDANCE WITH THE APPROVED PLANS CONTAINED IN THE APPLICATION. <br />With the acceptance of the above stipulation, the Division finds the application <br />in compliance with the requirements of this section. <br />VI. Hydrologic Balance: Ground Water - Rules 2.09.5, 2.04.7, 2.05.4(4), <br />2.05.6(3) and 4.05 <br />Baseline ground water hydrology information is presented in Section 9.5, pages <br />IV-23 to IV-36, and Section 5.6.3, page V-31-32 of Volurre I; Section 2.04.7 of <br />Volume III; and Volume V - Report on Hydrologic Impacts - in the permit application. <br />This information has been reviewed by the Division for compliance with the Rules <br />and Regulations. <br />Ground water occurs in both bedrock strata and unconsolidated alluvial formations <br />near the Trinidad Basin Mine. The alluvial formation is the only water-bearing <br />unit which has sufficient characteristics to be considered an aquifer. There is the <br />potential that mining will impact the aquifer in some way. <br />