Utility Easement Encroachment Approval

I am building a pool in my back yard and the City planning department of Pembroke Pines Florida says I need an Utility encroachment letter from all utility companies in order to get permits approved. I did call 811 and nothing for comcast passes across the area where I want to build the pool. I basically need a letter from Xfinity indicating that it is OK--or that they have no objection--for me to build my pool.  I've called and talked to almost 10 people and nobody can help me.  Please help!