Date: Tue, 29 Aug 95 08:41:02 EDT
From: Emergency Information Administrator
Subject: Guyana: Chemical Spill DHA-04
DHA-GENEVA SITUATION REPORT NO. 4
GUYANA CYANIDE MINE WASTE SPILL
(29 August 1995)
1. THE PAN AMERICAN HEALTH ORGANIZATION (PAHO) HAS REPORTED ON A
RECENT MISSION TO THE SITE OF THE RECENT GOLD MINE WASTE SPILL.
2. THE REPORT NOTES THAT AQUATIC LIFE IN THE OMAI CREEK AND AT
THE CONFLUENCE WITH THE ESSEQUIBO RIVER WAS COMPLETELY DESTROYED
IN THE SPILL.
3. THE REPORT ALSO NOTES THAT THE SPILL DID INITIALLY POSE SOME
ENVIRONMENTAL HEALTH RISK TO SMALL POPULATIONS OF APPROXIMATELY
100-200 PEOPLE ALONG THE FIRST FORTY KILOMETRES OF THE ESSEQUIBO
RIVER. THE MISSION FOUND THAT WHERE ALTERNATIVE SOURCES OF
DRINKING WATER WAS NOT AVAILABLE, BOTTLED DRINKING WATER WAS
PROVIDED BY THE MINING COMPANY OMAI GOLD MINES LIMITED (OGML).
4. FURTHER DOWN STREAM BY THE ROCKSTONE RAPIDS THE MISSION FOUND
THAT THERE WILL BE NO ENVIRONMENTAL HEALTH CONCERNS WITH REGARD
TO THE LEVELS OF CYANIDE DUE TO THE LARGE DISPERSION AND
DILUTION FACTOR AND OXIDISATION OF THE CYANIDE. HOWEVER, THE
DISCOLORATION OF THE WATER BY SUSPENDED CLAY HAS DISCOURAGED THE
USE OF WATER FROM THE ESSEQUIBO.
5. THE MISSION RECORDS THAT FROM PLUME OBSERVATIONS, MIXING OF
THE SPILL WITH THE WATERS OF THE ESSEQUIBO (14.4 MILLION CUBIC
METRES PER HOUR AVERAGE AUGUST FLOW RATE) WOULD HAVE PRODUCED A
DILUTION FACTOR OF 320:1 AT THE TOWN OF BARTICA, SOME 120
KILOMETRES FROM THE SPILL SITE. THE PAHO EXPERT ESTIMATES THAT
THIS DILUTION EFFECT ALONE WOULD REDUCE CYANIDE LEVELS FROM 30PPM
TO 0.094PPM (COMPARED WITH THE WHO GUIDELINE VALUE FOR FREE
CYANIDE OF 0.07PPM AND CANADIAN AND US LIMITS OF 0.2PPM AND
0.15PPM RESPECTIVELY).
6. PAHO FURTHER NOTES THAT THE ACTUAL CONCENTRATION OF CYANIDE IN
THE PLUME WOULD BE MUCH LOWER THAN THE 0.07PPM AT BARTICA GIVEN
THAT:
A) IDEAL PLUG FLOW CONDITIONS DO NOT OCCUR, THE PEAK
CONCENTRATION SPREAD OUT OVER A LARGER STRETCH OF THE RIVER,
B) CYANIDE IS NOT A STABLE COMPOUND AND EASILY OXIDIZES AND BREAKS
DOWN IN SUNLIGHT,
C) THE FLOW RATE DECREASED QUICKLY AFTER THE COMMENCEMENT OF
THE BREACH BECAUSE OF THE REDUCTION IN WATERPRESSURE DUE TO
THE LOWERING OF WATER LEVEL IN THE TAILINGS DAM,AND
D) ONLY 20 PERCENT OF THE CYANIDE LEVELS WERE FREE CYANIDE AND
80 PERCENT THE LESS TOXIC METALLIC CYANIDE.
7. IN A TRIP ON 23 AUGUST TO ALL SETTLEMENTS ALONG THE RIVER FROM
BARTICA TO OMAI, NO CASES OF CYANIDE POISONING NOR DEAD FISH WERE
OBSERVED BY THE PAHO EXPERT.
8. HOWEVER, THE PAHO REPORT NOTES THAT SAMPLING STRATEGIES USED
BY OGML WARRANTED CONCERN. THE PAHO EXPERT IDENTIFIED THAT ONLY
A SINGLE SURFACE SAMPLE WAS TAKEN NEAR SHORE AT DIFFERENT SITES.
THE PAHO REPORT RECOMMENDED THAT SAMPLES SHOULD HAVE BEEN TAKEN
AT THREE DIFFERENT POINTS ALONG THE CROSS-SECTION OF THE RIVER,
ABOUT 10M APART AND AT LEAST ONE METRE DEPTH.
+ DEPARTMENT OF HUMANITARIAN AFFAIRS =
TELEPHONE NO: +41-22-917.12.34
EMERGENCY TEL. NO. (IN CASE OF EMERGENCY ONLY): +41-22-917.20.10
DESK OFFICER: MR. GERARD LE CLAIRE DIRECT TEL: +41-22-917.11.73
PRESS TO CONTACT: MRS. MOULIN-ACEVEDO, DIRECT TEL: +41-22-
917.28.56
TELEX: 414242 DHA CH
FAX: +41-22-917.00.23
ELECTRONIC MAIL: UNIENET DIALCOM 141: DHAGVA
DPR 310 GUY
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