The day before the Pad Abort test attempt (May 5, 2015) SpaceX test fired the SuperDraco engines in a hot fire. Similar to how they test the Falcon 9 a day or three before launch, the engines spin up and fire, the booster/capsule is mechanically held down for the test.
But normally, SpaceX burns LOX/RP1 whose exhaust is carbon dioxide, water, and some sulfur by products. Basically car exhaust, just lots more of it.
For the Pad Abort vehicle, it is Nitrogen Tetroxide and MMDH which are astonishingly nasty nasty fluids. They are horribly corrosive and dangerous to humans. The products of full combustion are not very bad (water, ammonia, and other benign things) but you cannot guarentee 100% full combustion, and this stuff is just plain nasty. (Potential additional question will be for capsules landing on land, how much work will be needed before they can leave the capsule safely. Shuttle had people in Hazmat suits cleaning up, before the crew were allowed to leave from its NTO/MMDH thrusters.).
How much cleanup was required at the pad after the test?
Looking at the pictures, they did use the Niagara water deluge system. Was that sufficient to wash away any issues? (If so, do they process the deluge system water before letting it flow back into the Florida waterways?)