I agree with the above post but would also suggest reviewing a good "introduction to environmental engineerig" textbook. The NCEES and Naimpally books were good but didnt cover the entire range of possible questions.
All that aside, even if you only used NCEES and Naimpallys books, study hard and you should do well. Those were the only texts that I used and passed the first time but I practically memorized the material. I suggest answering all the questions at least three times. Balancing study time for the AM and PM can be tough but you can do it!