I'm a civil/environmental engineer and happened to have a chance to read that remediation report. Below is my input to this thread:
As some people already know, this groundwater/soil contamination is originated from the waste injection to the groundwater table by the former base due to that the injection contained toxic chemicals, such as VOCs (Volatile Organic Compound; quite coincidence with Village of Columbus), which would evaporate through the soil thereby causing soil contamination. Moreover, the chemicals contained in groundwater would form a plume, moving and diffusing with the groundwater flow. As of today, the plume is located across the entire Irvine down to the coastline. So not just on the former base, many other areas are under the threat of that plume. But a good fact is that the groundwater table in the Irvine Basin is very deep, at least 100 feet below the ground. The current treatment is by pumping, which will have been operated for another 10 years or so.
Secondly, it is about the disclosure law for land developers. They are required to disclose this type of environmental information along with others (such as earthquake fault and dam failure impact zone) to buyers. Do they know more details? I don’t think so, because this type of environmental responsibility is not imposed on developers during their EIR approval.