L7 Application Pools Health Monitoring on a single website with multiple applications

I have found a few variation of suggestions to my question but none have completely answer it. We have web servers hosting a single website with multiple application and they are part of a single VIP. We need to be able to mark a application pool down as opposed to the whole node. Traffic will continue to access the other healthy application pools. We can't use host header as other suggested because this server only has one website with multiple application pools and 1 IP. Is there a way to redirect traffic using iRULE or any other options to accomplish this? This basically will be a Layer 7 monitoring. Thanks.