Well, these things claim to allow you to do this, but I don't trust anything that is buried. I believe that they've been used in modular or manufactured homes for some time. Take a look:

http://www.molex.com/cgi-bin/bv/molex/jsp/family/intro.jsp?BV_SessionID=@@@@1822063810.1218670744@@@@&BV_EngineID=ccceadeelgmemhhcflgcehedffgdfmk.0&superFamOID=-8804&pageTitle=Introduction&channel=Products&familyOID=-9408&chanName=family&frellink=Introduction

---Ed---

"But the guy at Home Depot said it would work."