ASP.NET Memory Leak: Byte arrays rooted in System.Security.Policy.Evidence

Today I got a question from a reader (Chris) about a memory leak they are seeing in their application
When we do a '!dumpheap -min 85000 -type Byte[]' we can see 100s of byte array objects using up ~545MB of memory. A majority of the objects are the same size (either 4.5 or 9MB in size). Looking at the memory addresses, they all appear to be different copies of our assemblies. And when we do !GcRoot on those addresses they all either have no results returned, or show a rooted System.Security.Policy.Evidence object:
DOMAIN(000FDC18):HANDLE(Strong):-:Root:-(System.Security.Policy.Evidence)->
(System.Collections.ArrayList+SyncArrayList)->
(System.Collections.ArrayList)->
(System.Object[])->
(System.Security.Policy.Hash)->
(System.Byte[])
Through PerfMon we can see our Large Object Heap size grow and grow ...