First let me say, i have nothing but respect for the UK and the British people, but I have a question. Seems the police are too darn polite. If american cops wanted to search a landfill, they would arrive in force, search warrant in hand and start digging. They would not be warning the locals that they might have to shut their windows due to smell, or cancel their outdoor activities. I almost think this culture of politeness has slowed this entire investigation. Maybe I watch too much tv.
I'm not sure what your question is, but I don't think the search has been delayed because of concerns about the smell.
They've taken the opportunity in the time between announcing the search and actually getting started to warn the community about the issues, but I really don't think the decision to wait until now has been based on worrying about the locals being bothered by the smell.