Answer: According to your zip code you are in zone 5, yes. There are many different plants you could try ranging from lilac to viburnum to rhododendron, however based on your description I am not certain there will be room for a large shrub; the roots of most plants are just as expansive as the top growth so they might reach the tank. (Rhododendrons are shallow rooted and thus might be a good choice if the growing conditions in that spot are suited to a rhododendron.) You need to leave room to access the tank clean out and also allow ample space away from the leach lines. I would suggest you consult with your local county extension as to recommendations for planting by septic systems.
In addition to the septic question, you also need to take into account how much sun reaches that corner and at what time of day, whether or not it is especially windy especially in winter, and what type of soil is there, and how much space you have for the plant to grow and mature. Your local professionally trained nursery staff should have suggestions based on a more detailed understanding of the growing conditions in that spot as well as your overall design goals. Good luck with your planting!
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