THE SYOSSET LANDFILL SUPERFUND SITE (THE LANDFILL OR SITE ) IS A NATIONAL PRIORITIES LIST SITE LOCATED IN THE HAMLET OF SYOSSET IN THE TOWN OF OYSTER BAY (THE TOWN ), NASSAU COUNTY, NEW YORK. THE SITE COVERS APPROXIMATELY 35 ACRES AND IS 50 YARDS NORTH OF THE LONG ISLAND EXPRESS- WAY. IT IS BORDERED TO THE SOUTHEAST BY MILLER PLACE, TO THE SOUTHWEST BY PROPERTY FORMERLY OCCUPIED BY CERRO CONDUIT COMPANY, TO THE NORTHWEST BY THE LONG ISLAND RAILROAD, AND TO THE NORTHEAST BY A LARGE RESIDENTIAL AREA. THE SOUTH GROVE SCHOOL IS LOCATED JUST TO THE NORTHEAST OF THE SITE. THE SITE OVERLIES A SOLE SOURCE DRINKING WATER AQUIFER, THE MAGOTHY AQUIFER. FIVE PUBLIC WATER SUPPLY WELLS ARE WITHIN SIX THOUSAND FEET OF THE SITE. THE LANDFILL IS OWNED BY THE TOWN, WHICH OPERATED IT FROM APPROXIMATELY 1933 TO 1975. PRIOR TO 1967, THERE WERE NO RESTRICTIONS ON THE TYPE OF WASTE THAT COULD BE DISPOSED OF AT THE LANDFILL AND IT WAS USED TO DISPOSE OF RESIDENTIAL SOLID WASTE, UNTREATED SEWAGE AND CESSPOOL LIQUID SLUDGES, AS WELL AS COMMERCIAL, INDUSTRIAL, DEMOLITION, AND AGRI- CULTURAL WASTES. IN 1967, WITH THE OPENING OF THE OLD BETHPAGE LANDFILL TO THE EAST OF SYOSSET, THE TOWN STOPPED USING THE SITE TO DISPOSE OF ITS DOMESTICALLY-GENERATED WASTES. THE TOWN ALSO DIRECTED SOME INDUSTRIAL GENERATORS TO USE THE OLD BETHPAGE LANDFILL, BUT SOME INDUSTRIAL WASTES CONTINUED TO BE DISPOSED OF AT THE SIT