Above Ground rigid steel conduit over creek
Christy is one of the many companies that make handhole boxes (like a minature manhole) for underground conduit / cable.  It gives you access to pull or splice at junction points on an underground cable / conduit rum.  

I am going to assume the rigid conduit goes into the bank of the stream on either side and a direct burial cable will go in the pipe, or a direct burial cable will be spliced to something else at those points.  

So someone suggested you'll need a handhole at those splice or pull points, which is correct.  

(Unrelated to the question, also assuming the cable is supported by a bridge or something because you can't span 30' with unsupported conduit, and that the poster is aware the permitting for things crossing streams can be ridiculously difficult.)