Lexington KY home with ~20 PCi/L radon levels in a basement adjacent to a crawlspace (see attached plan). Radon levels directly above the crawlspace are ~14 PCi/L. The sub membrane radon mitigation design shows a 50ft perforated drainage pipe as a continuous loop. Is there be any reason NOT to loop the 50ft drain pipe? Has anyone done something similar? 

Thanks – Bob 

House Notes:
– House was built in 1972
– CMU block basement and Crawlspace
– Tight clay soil under basement slab
– Crawlspace is uncovered/bare and composed of rock and dirt. 
– Rafters/rim joist in crawlspace are uninsulated and not covered with a membrane. 
– Basement walls/ rafters are uninsulated and not covered with a membrane.
– Crawlspace is not vented
– The rafters supporting floors above basement and crawlspace run across the block walls without any rim joist or seal (vented to the basement…).
– There is duct work that runs across block wall (6″ metal) I have yet to see it condensate, a ~32″ return (2 joist bays) turns up the stud wall directly above the block wall. Gas lines and electrical lines also run over the block wall though the open joist bays.