Tthe Utility Manual is a regulation and is part of DE Administrative Code and companies making installations within State roadway rights-of-way need to abide by the requirements. 

http://deldot.gov/information/business/drc/manuals/utilities_manual_2008_may_5.pdf

The below link other takes you to the official administrative code version which does not contain appendices.

http://regulations.delaware.gov/AdminCode/title2/2000/2400/2401.shtml#TopOfPage