Unknow oil on ground 8 feet from house

[Nelson Del Castillo]

Hi Everyone, I have ran into a weird situation, I have a house under contract in west haven Connecticut and we noticed on the left side of the house about 7 feet away, there is some swamp land with a strong smell of oil. We took a sample of the water that has acumalated there and confirmed that in fact there is oil there. Now the oil is right on the property line and I believe the city owns the swamp land but being that it’s so close to the house I’m not sure who would be responsible and what the cost to take care of something like this would be. Has any one encountered this kind of situation? Any input would be appreciated. ( there Is no oil In the house, It Is natural gas heatIng) Thanks Ct Ny Ma