It depends on exactly what rights the utility has through their easement: if they only have the rights to access that area and run their lines, but no right to control or restrict other uses, then so long as you do  not infringe on their rights (or damage or endanger their equipment) you should be able to do this. The key is to not infringe on whatever rights are granted them through the easement.It would be best to have a real estate attorney review the easement with you, to see the different parties' respective rights and obligations.