The lines will go away eventually. Fertize the sod and give it a GOOD watering every few days. Dont water it everyday as you'll want to encourage the grass to grow deep roots. Watering it everyday discourages this. Like I say, with a good fertilizing the dead parts will eventually come back, and just water it causally from that point on, but be mindful of the amount of heat & sun.
On these HOT days, watering it everyday is a good idea.. if its cool or rainy out, every few days (read: twice a week) is enough.
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