Front Yard Tree Planting - Not to Be!

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We were hoping to plant some plum trees in our front yard between the sidewalk and the street. This is done all around us on almost every street in the neighborhood and looks fantastic. Trees are planted like this across the street from us but none are on our side of the street. We decided to look into planting some and had the utilities marked. There ended up being a sewer line underneath the grass strip, meaning no trees for us. We figured there was a reason we didn't have any but it's nice to confirm that's why.