saskatoon berry (Amelanchier alnifolia) over sewer line?

(Question)

Hi there – We live in a fairly typical old house in Toronto. Last spring, we planted a saskatoon berry shrub (Amelanchier alnifolia) in our front yard, then learned it is basically positioned over the sewer line. Is the root system of the shrub likely to interfere with the sewer line? If the saskatoon needs to be moved, how far away would you advise? It is still small — maybe 2 feet tall. Thanks so much for your advice!

 

(Answer)

Thanks for contacting the Toronto Master Gardeners with this interesting question.

You are concerned that the roots of a recently planted  Amelanchier alnifolia (saskatoon berry shrub) may interfere with the sewer line between your house and the street.

The quick answer is “probably not”. First of all, the fibrous roots of this shrub form a spreading, suckering root system that is relatively shallow; generally it can naturalize into multi-stemmed clumps. Secondly, according to the Design Criteria for Sewers and Water Mains in the City of Toronto [https://www.toronto.ca/wp-content/uploads/2018/02/864c-ecs-specs-dcm-Toronto_Sewer_and_Watermain_Manual_1st_Revision_March2014.pdf ],”the minimum depth of a sanitary sewer will be  2.75 metres measure from the centre line elevation of the road to obvert of the sewer”. It is doubtful that the root system of a mature  Amelanchier would penetrate that far down. If for any reason, the sewer line needs to be replaced sometime in the future, the shrub could easily be transplanted.

You are to be commended on your choice of the Amelanchier alnifolia in your front yard. Even though this native species is naturally found in northern Ontario near the Manitoba border, it is easily grown in Toronto and has many benefits–berries for wildlife and attractive fall colours. Enjoy your shrub.

All the best.