2009-09-25_PERMIT FILE - M2009076 (42)

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ACT. THE RESULTS OF THE MODEL CLEARLY INDICATE AN ADVERSE IMPACT ON CLEAR CREEK DUE TO COLLAPSE OF THE WASTE ROCK PILES AT THE BIG FIVE TUNNEL. SIMILAR ANALYSES OF COLLAPSE OF THE GREGORY TAILINGS INTO NORTH CLEAR CREEK HAVE BEEN PERFORMED. 0ULTS FROM THIS EFFORT INDICATE THAT BOTH AWQC AND MCL VALUES WOULD BE EXCEEDED IN CLEAR CREEK GOLDEN AS A RESULT OF A COLLAPSE. IMPACT DUE TO RUNOFF: IN ADDITION TO COLLAPSE OF THE TAILINGS AND WASTE ROCK PILES, MATERIALS WILL ALSO ENTER THE STREAM DUE TO RUNOFF FROM THE PILES DURING SNOW MELT AND STORM EVENTS. THE RESULTS OF THE ANALYSES OF SAMPLES TAKEN ON CLEAR CREEK AND NORTH CLEAR CREEK DURING STORM EVENTS INDICATE THAT THE AVERAGE TOTAL ALUMINUM AND ZINC CONCENTRATIONS EXCEEDED AWQC VALUES BY FACTORS OF 69 AND 15 TIMES, RESPECTIVELY. THE RESULTS INDICATE POTENTIAL IMPACT ON AQUATIC LIFE DUE TO RUNOFF DURING STORM EVENTS. IMPACTS ON HUMAN HEALTH DUE TO RUNOFF FROM THE SITES ARE MINIMAL BECAUSE THE STORM EVENTS ARE OF LIMITED DURATION. SUMMARY OF EXPOSURES TO AQUATIC LIFE: THE MAJOR CONCLUSIONS OF THE ASSESSMENT OF EXPOSURE TO AQUATIC LIFE CAN BE SUMMARIZED AS FOLLOWS: • SEVERAL OF THE CHEMICALS OF CONCERN ARE AT CONCENTRATIONS THAT EXCEED THE AMBIENT WATER QUALITY CRITERIA FOR THE PROTECTION OF FRESHWATER AQUATIC LIFE (AWQC). IN PARTICULAR, CONCENTRATIONS OF ZINC, COPPER, AND ALUMINUM CONSISTENTLY EXCEED THE ACUTE AND CHRONIC AWQC. IN ADDITION, CONCENTRATIONS OF MANGANESE IN THE WATER EXCEED THE LOWEST OBSERVED EFFECT LEVEL IN RAINBOW TROUT. BECAUSE AQUATIC ORGANISMS ARE EXPOSED TO A MIXTURE AND NOT INDIVIDUAL CHEMICALS, TOXIC EFFECTS MAY BE EVEN GREATER THAN INDICATED BY COMPARISON TO THE AWQC. ALTHOUGH SOME FISH MAY TOLERATE THE CHEMICALS IN THE CREEKS, IT IS HIGHLY UNLIKELY THAT THE POPULATIONS OF FISH . FOUND IN THESE CREEKS ARE FREE OF TOXIC EFFECTS. A MORE DETAILED DISCUSSION OF THESE EXPOSURE PATHWAYS AND THE RESULTING RISKS CAN BE FOUND IN THE PUBLIC HEALTH EVALUATION, SECTION 10 OF THE REMEDIAL INVESTIGATION REPORT. IT IS CLEAR THAT A RELEASE OR SUBSTANTIAL THREAT OF RELEASE OF A HAZARDOUS SUBSTANCE OR POLLUTANT OR CONTAMINANT INTO THE ENVIRONMENT HAS OCCURRED AT THE CLEAR CREEK/CENTRAL CITY SUPERFUND SITE AND THAT REMEDIAL ACTION IS JUSTIFIED. #CR COMbWNITY PARTICIPATION ON OCTOBER 26, 27, AND 28, 1987, ANNOUNCEMENTS FOR THE PUBLIC COMMENT PERIOD AND THE PUBLIC MEETING TO BE HELD CONCERNING THE OPERABLE UNIT NO. TWO FEASIBILITY STUDY (FS) WERE PUBLISHED IN THE WEEKLY REGISTER CALL, THE GOLDEN TRANSCRIPT, AND THE CLEAR CREEK COURANT. THE ADS ANNOUNCED THE NOVEMBER 9 THROUGH DECEMBER 8, 1987 PUBLIC COMMENT PERIOD AND THE NOVEMBER 24 PUBLIC MEETING, GAVE A BRIEF DESCRIPTION OF THE REMEDIAL ACTION ALTERNATIVES, AND STATED THE RATIONALE FOR THE PROPOSED PLAN. THE PRESS RELEASE, ALONG WITH THE PROPOSED PLAN, WAS MAILED TO THE APPROXIMATELY 300 NAMES ON THE EPA-COMPILED CLEAR CREEK/CENTRAL CITY SUPERFUND SITE MAILING LIST. THE PRESS RELEASE NOTIFIED THE PUBLIC OF THE AVAILABILITY OF THE ADMINISTRATIVE RECORD FOR THE SITE AND INFORMED THEM OF LOCATION OF THE INFORMATION REPOSITORIES WHICH HAD PREVIOUSLY BEEN ESTABLISHED FOR THE SITE. THOSE INFORMATION REPOSITORIES ARE LOCATED AT THE EPA LIBRARY IN DENVER, THE GILPIN COUNTY COURT HOUSE IN CENTRAL CITY, THE IDAHO SPRINGS PUBLIC LIBRARY AND THE IDAHO SPRINGS CITY HALL IN IDAHO SPRINGS, AND THE GOLDEN PUBLIC LIBRARY IN GOLDEN, COLORADO. THE ADMINISTRATIVE RECORD IS LOCATED AT THE GILPIN COUNTY COURTHOUSE AND THE EPA LIBRARY. AN INDEX OF THE ADMINISTRATIVE RECORD IS LOCATED AT EACH INFORMATION REPOSITORY AND IS ALSO ACHED TO THIS RECORD OF DECISION. ON NOVEMBER 24, 1987, EPA HELD A PUBLIC MEETING CONCERNING THE OPERABLE UNIT NO. TWO FS AND THE PROPOSED PLAN. APPROXIMATELY 50 PEOPLE ATTENDED. MAJOR CONCERNS RAISED WERE HOW EPA'S PRESENCE IN THE AREA WAS AFFECTING THE ECONOMY OF THE AREA, THE PERCEIVED LARGE AMOUNTS OF MONEY WHICH EPA IS SPENDING ON STUDYING THE SITE, AND WHETHER REMEDIAL ACTION AT THE SITE IS WARRANTED. AT