NATURE OF THE CASE: THE CHROMIC ACID TANK AT THE NOVACO FACILITY LEAKED AN UN KNOWN QUANTITY OF CHROMIC ACID INTO THE GROUNDWATER ON OR BE FORE JUNE 13, 1979. WITHIN 24 DAYS FOLLOWING NOVACO'S DETEC TION OF THE LEAK, CHROMIUM WAS DISCOVERED IN BOTH NOVACO'S WELL AND THE DOWN GRADIENT (WEST) VFW POST WELL. FROM JULY TO NOVEMBER 1979, NOVACO EXTRACTED GROUNDWATER FROM THE VFW AND THEIR OWN WELL. APPROXIMATELY 122,000 GAL- LONS OF CONTAMINATED GROUNDWATER WAS EXTRACTED AND TREATED ON SITE USING A CHEMICAL REDUCTION PROCESS. THIS OPERATION WAS DISCONTINUED BY NOVACO BEFORE ALL THE CHROMIUM WAS REMO- VED FROM THE AQUIFER, APPARENTLY WHEN INSURANCE FUNDING OF THE OPERATION RAN OUT. BETWEEN 1979 AND 1981, THE MICHIGAN DEPT. OF NATURAL RE- SOURCES (MDNR) AND THE MONROE COUNTY HEALTH DEPT. MONITORED THE GROUNDWATER. CHROMIUM CONCENTRATIONS IN THE WELLS GENE- RALLY DECREASED AND NO NEW WELLS BECAME CONTAMINATED. HEXA- VALENT CHROMIUM CONCENTRATIONS UP TO 940,000 UG/1 WERE MEA- SURED, WELL OVER THE FEDERAL DRINKING WATER MAXIMUM CONTAMI- NANT LEVEL (MCL) OF 50 UG/1. THE NOVACO SITE WAS PLACED ON THE NAT'L PRIORITIES LIST (NPL) IN SEPT. 1983, RANKING IN GROUP 7. THE REMEDIAL INVES TIGATION (RI) FIELD WORK WAS CONDUCTED DURING 1984-85. NOTICE LETTERS AND INFORMATION REQUESTS WERE SENT TO DAR- REL BROOKS JUNE 14, AUGUST 23, AND NOV