Danbury is considering listing a blighted property as surplus, having seized after  condemning it.  The former Amphenol site behind police headquarters was acquired by the City two years ago, but the property is contaminated by arsenic, mercury and other chemicals.  The 3 acres had been proposed as a site basketball courts, but even after an environmental cleanup it was determined that it could not be used for residential or recreational purposes.  Mayor Joe Cavo wrote a letter to the City Council asking that the East Franklin Street property be listed as surplus because there's an interested buyer.  Joe Cavo did not say who wanted to but the land, which runs behind a row of single-family homes onto Maple Avenue. The property is zoned for light-industrial use.