Rundown and vacant buildings and properties can bring down a community. They attract criminal activity and be a way to harbor disease. According to the New Jersey Department of Environmental Protection, some abandoned sites are a brownfield. To be a brownfield, the site must have a history or assumption of contamination in the area.
The government encourages the redevelopment of such places to better communities, which means that if you are a contractor, you could get many benefits from building on this type of site.
You will not have to worry about the contamination in most cases. The law requires landowners must clean up the site. There is an exception for governments in some cases, but even then, you can probably work with them on clean up. If you do need to do it yourself, there are plenty of funds available to you to do so through the government.
By cleaning up the site and rebuilding, you not only create a usable structure but also deter crime and reduce pests in the area that may have called the old site home. This can have a huge impact on the community. It erases a local eyesore and puts in something that is useful and beneficial to the public.
You can find brownfield properties through the Brownfield Development Area program. It has a list of sites with information available. You can access the list online. However, the best place to find a site is to ask in the local area as people are eager to have brownfields redeveloped.