Waterless urinals and hygiene
The hypothesis that waterless urinals will have less bacteria compared to water based urinals, is proven to be true.
Waterless urinals help to reduce water wastage and also help to lower the cost of treating waste water. In addition, they are more hygienic and are odor free. Moreover, since there is no need for flush valves and external water sources, the maintenance cost is also lower.
This science fair project can be modified by collecting bacteria samples from other areas around the urinals such as from the floor, walls or wash basins near the urinals.
Also, to produce more accurate results, you might want to consider collecting swab samples from at least 5 different spots/locations within each urinal.
Characteristics of a waterless urinal - http://www.ehow.com/list_5965246_characteristics-waterless-urinal.html
Waterless urinals: features, benefits and application - http://www.atypon-link.com/CPUB/doi/abs/10.3992/jgb.1.1.55?cookieSet=1&journalCode=jgb
The agar in the Petri dishes should be properly disposed of and the Petri dishes decontaminated after the experiment. This can be done by washing the Petri dishes with bleach.