It appears the issue was discovered and remediated quickly, so it's doubtful the tenant was exposed to anything in significant amounts or for long periods.

The tenant and I have agreed to extend the stay another 2 weeks. 

Additionally, it can help maximize renovations and improvements.A Cost Segregation study is an IRS approved federal income tax tool that increases near term cash flow by utilizing shorter recovery periods for depreciation to accelerate return on investment.

I found this deal through a relative, we negotiated without an agent through a period of x months.

Why not just extend the settlement date and wait?

If you wanted to pull funds out of this property next year, then I wouldn't recommend it because these loans have prepayment penalty periods.

These charts show data across each market on rent trends for re-rentals, where a new lease is signed on an existing rental property, and renewal leases, where an existing lease is renewed for an extended 2-year period.These data graphs show the percentages of growth and the number of leases in each category by city. 

That said, long-term the appreciation you get in the Puget Sound region is superior to many other markets, so assuming you find an excellent property management company that is able to screen tenants and only put in very well qualified, vetted occupants and you experience limited issues over the holding period, you'd likely come out ahead retaining the Mill Creek property if your financially able to do so and still buy wherever you are headed out of state.

Prepayment Penalty Period.

What happens if a flood or fire occurs to the property during the redemption period?