LESS THAN STANDARD SEPARATION OCCURRED BTWN LGT ON A FAR FOR RWY 17L AND HVT BEING VECTORED FOR THAT RWY DURING A RWY CHANGE. BLANK

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AN HVT LANDED RWY 35 R AND WAS UNABLE TO CLEAR THE RWY BEFORE LGT Y WHO WAS ON SHORT FINAL FOR 35 R. LGT Y WAS SENT AROUND AND INSTRUCTED TO CLB TO 7000 FT AND FLY RWY HEADING LGT Y WAS ALSO ISSUED TFC 12 O'CLOCK AT 8000 FT. THE TFC WAS TO STAY AT 8000 FT. SOMEONE (UNKNOWN) STARTED TRANSMITTING ON TWR FREQ (119.5) WHEN THE TFC; HVT X WAS OBSERVED ON FINAL FOR 17L. LGT Y WAS GIVEN A RIGHT TURN AWAY FROM HVT X FOUR TIMES BEFORE HE ACKNOWLEDGED AND MADE THE TURN. LGT Y FLEW CLOSE TO HVT X AS HVT X LANDED RWY 17L VISUALLY. THE LOC 17L WAS OFF (35R LOC WAS STILL ON FOR LGT Y). THE RVR ON 17L WAS TOUCHDOWN 800 FT; MIDPOINT 1000 FT; ROLLOUT 6000 FT+. ARPT AND WX CONDITIONS WERE POOR AT BEST. CENTER FLOW WAS 30 ALL DAY AND THEY WERE HOLDING AT ALL OUTER FIXES. SOMEONE IN APCH INCREASED THE FLOW RATE AND SHORTLY AFTER THIS THERE WAS MORE ACFT IN THE SYSTEM THAN THE ARPT COULD HANDLE SAFELY. SUPPLEMENTAL INFORMATION FROM ACN 100125: HVT X WAS ON FINAL APCH TO RWY 17L; LGT Y WAS MISSED APCH TO RWY 35R (OPPOSITE DIRECTION) THE TWO ACFT PASSED; OPPOSITE DIRECTION APPROX 3 MI N OF THE ARPT; APPROX 1/2 MI AND 300 FT APART. THIS INCIDENT OCCURRED DURING A TRANSITION FROM ILS APCHS TO 35R; TO ILS APCHS TO RWY 8 R AND 17L. THE ARPT ACCEPTANCE RATE (FLOW RATE) WAS CHANGED FROM 30 ACFT PER HOUR TO 55 PER HOUR. THE TFC ARRIVED AT THE ARPT (NEW FLOW RATE) WHILE WE WERE STILL 'ILS-ING' TO RWY 35 R; RESULTING WITH TOO MANY AIRPLANES ON VECTORS NOT BEING ABLE TO LAND. I SUGGEST; DO NOT UP A FLOW RATE UNTIL THE TRANSITION TO A RWY HAS BEEN ACCOMPLISHED. CALLBACK CONVERSATION WITH REPORTER REVEALED THE FOLLOWING: CALLBACK TO APCH CTLR WHO GAVE EXPERIENCE LEVEL FOR BOTH LC AND APCH CTLR. APPARENTLY THE AREA MGR AND THE ARTCC FLOW CTLR DECIDED TO GO TO CROSS RWY OPERATION IFR; IE: RWYS 17 AND RWYS 8. ARPT WAS STILL IFR WITH TOUCHDOWN RVR 800 MIDFIELD 1000 AND ROLLOUT 6000. TFC FLOW WAS INCREASED FROM 30 PER HOUR TO 55 TO 60 PER HOUR. BEFORE THEY RWY CHANGE WAS COMPLETE THE TFC ARRIVED IN THE APCH CTL AIRSPACE. RPTR SAYS ACFT WERE ON VECTORS ALL OVER THE PLACE; TOO MUCH TFC FOR SAFE HANDLING WHILE RWY CHANGE WAS STILL IN PROGRESS. SUPPLEMENTAL INFORMATION FROM ACN 99907: WX HAD BEEN DOWN SO DEN WAS MAKING APCHS TO RW 35 R (LOWEST MINIMUMS). AT APPROX XA40 DEN DECIDED WX HAD IMPROVED ENOUGH TO MAKE VISUAL APCHS. DENVER APCH WAS IN THE PROCESS OF CHANGING APCHS FROM RW 35 TO RW 17. (THIS STARTED WHEN WE WERE INSIDE OF KEANN. THE APCH WAS CHANGED 2 TIMES; RW 35; TO 8 TO 17. UNDER APCH CONTROL WE WERE GIVEN VECTORS ALONG THE 17L APCH LINE; THE ALS-GS WAS OFF BECAUSE THEY WERE STILL HAVING 35 R LNDGS. WE TOLD APCH WE HAD VISUAL CONTACT WITH THE ARPT. LGT Y MISSED ON 35 R. WE HAD HIM VISUALLY THE ENTIRE TIME. ABOUT THE TIME I THOUGHT I MIGHT HAVE TO BREAK RIGHT TO AVOID LGT Y; HE BROKE RIGHT. WE CONTINUED THE APCH AND LANDED WITHOUT ANY PROBLEM. SUPPLEMENTAL INFORMATION FROM ACN 99909: ATC APCH SET UP A HIGH POTENTIAL CONFLICT SITUATION. AT THE INITIAL SET UP; THE FOG BANK WAS NOT A MAJOR FACTOR. WE CAN ONLY SURMISE THE LNDG RWY DIRECTION CHANGE OCCURRED TO SUPPORT NIGHTTIME NOISE ABATEMENT POLICY; AS THE WIND WAS ALSO NO SIGNIFICANT FACTOR; WE DISCUSSED; ABOUT 15 MI OUT; THE POTENTIAL CONFLICT APCH WAS SETTING ABOUT. (DISCOVERED LATER THE WDB HAD CLRED 35 R INTO A DENSE FOG PATCH; COULD NOT FIND TURN FOR PARALLEL TAXIWAY; STOPPED; HVT THEN PASSED LNDG 17).