| http://www.w3.org/ns/prov#value | - Since its inception in 1972, Pennsylvania One Call System has increased its membership from 6 utilities to 3,478 underground facility owner/operators from the following industries: cable television, electric, gas, propane, Marcellus shale, pipeline, sewer, telecommunications, telephone, water and government, including state, county, city, borough, townships of the 1st class, townships of the 2nd c
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