Do you mean what appear to be old foundations? Those are [I believe] some type of crops, with dirt roads running between.
Then there's the sewage treatment plant directly on the other side of the power lines. [I don't recommend trying to access the park through that, at least when I was last there.]
Speaking of which, some northern access points to the park include Kirkpatrick Lane [behind Johnnies Motors (on Bloomfield Ave.) in West Caldwell] ,
Also, a [sometimes very muddy
] trail that starts at the southwest corner of Richard Park, [Bloomfield Ave. to the end of Richard Ave.]
Skeeter spray highly recommended.