2024-04-04_REVISION - M1990057 - Laserfiche WebLink

Home Browse Search

MEMO District Board,Leadville Sanitation District Union Milling—Permit M1990-057 MIO \/ \"' Job No.:1119.2e March 18,2024 corasu, - dcra�Eas Page 3 of 4 Low level mercury is present throughout Leadville in the soil,water,and air due to historic mining operations.The potential for increased infiltration into the sewer collection system as previously stated from the new crushing facility could increase mercury and other metal constituents to the WWTF possibly resulting in effluent compliance violations for the District. The WWTF operates under the Colorado Discharge Permit System Permit Number CO0021164.The District's permit limit for total mercury is 0.077µg/L.The permit limit for potentially dissolved cadmium ranges from 1.1 to 1.6µg/L, and the limit for potentially dissolved zinc ranges from 268 to 480µg/L varying seasonally with hydrologic fluctuations. The permit also requires the District to report effluent limits for an extensive list of pollutants including arsenic, chromium,copper,cyanide,iron,lead,manganese, molybdenum,nickel,selenium,silver,uranium,sulfide, nonylphenol,cesium,radium,strontium,thorium,BTEX,and benzene. Since the Mill is located directly adjacent to the District's WWTF,the wind transport of metals from trucks entering and leaving the facility as well as ore,topsoil,and overburden stockpiles and dust from the crushing facility could have detrimental effects and possibly contaminate the open air wastewater treatment basins at the WWTF.While the applicant proposes dust control of the mine dump material with spray water,JVA does not believe this will be an effective method for completely eliminiating low level metals from the air. Effects from metals transport by air to the WWTF could be seen immediately or could occur over a period of time since the District has extremely low level metals limits inµg/L and is required to monitor metals on a frequent basis in the wastewater effluent and report this information to CDPHE.Violations of the discharge permit limits would lead to fines to the District increased rates for the residents of Leadville. Also,it's important to note that the tailings detection limits per Table 4-30 Mill Tailings TCLP Results below are in mg/L for the metals listed while the District's permit limits are inµg/L. If the Mill is only required to test the tailings to mg/L,they could be reporting non detectable values because of the test methods utilized are not capable of measuring to low levelµg/L limits.JVA recommends the testing and reporting of all metals for the Mill be changed to µg/L for low level metals analysis.The mercury and cadmium levels tested in the Mill Tailings exceeds the limits set in the District's discharge permit.The Mill states that zinc dust will be used in its process to precipitate gold and silver from cyanide,though concentrations of zinc on site were not specified.