How Should I Depreciate a Sewer Line on my Taxes?

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I had a sewer line collapse in my duplex last fall - the old clay pipe collapsed, causing black water leakage into my basement and I called in Roto Rooter for an emergency containment and restoration since I had tenants living in one half and was actively showing the other half. It was damn expensive - I was out of pocket $19,887 and eventually received an insurance reimbursement for a little over $5k. For this they did excavation through the entire length of the basement and yard, new concrete, black water restoration, etc.

Now that I'm filing taxes myself through TurboTax (as I always do), I'm a bit stumped as to how to deduct. IRS.gov says any restoration is an improvement, and given the amount, I don't qualify for a Safe Harbor and would probably trigger some questions if I put it as a repair, so I'm pretty set on depreciating it.

Does anyone know how I'd handle that? I've seen various opinions around the internet saying 5 yrs, 15 yrs, 27.5 yrs, or just do an exception all at once. And do I need to break out what was spent on excavation vs restoration or any other classification? 

And also, I assume I'd only deduct the net amount of about $15k that I paid ($19,887 minus the $5k reimbursement from insurance?).

Big thanks to anyone with some insight on this!