The first step to writing a business report is to understand the purpose and report type. In this case, an informational report is needed for the audience to come to a conclusion as to whether the land is safe to build an office park on the property. The next step is to determine the audience, the report would cater to. Since the audience, i.e., the CEO just needs to make a decision, the technical aspects can be excluded from the report and just the major findings can be discussed.
The revision seems to be brief, enumerated and in keeping with the mindset of the audience. The CEO (audience) at whom the letter is aimed is not looking for the details of the investigations and testing, just for the outcome or the result to determine whether the site has been affected by hazardous waste or contaminated by groundwater. On the other hand, the first draft seems to be giving a lot of unnecessary but key information related to the findings of the tests and investigations. Although the information is very important, it is not necessary because the CEO will ultimately judge whether the site is safe or not based upon the results of the investigations.