Water in your pool has a pH of 7.0 (neutral) and any chlorine leaving the water as a gas would not likely be impacting your evergreens as it is heavily diluted by the air. There could be winter damage, rodent damage, cankers involved. Plants will take 2-3 years to recover from being transplanted and that makes them more vulnerable than established plants from any environmental impact. if Canada has the equivalent of an Extension Service, ask for a more local answer to your question.
