Soil compaction and growth rate
Recently my neighbor put in a new septic field near my two year old thuja green giant hedge which is along the property line. My trees are about 6 ft tall now and during construction, heavy machinery passed right over their driplines. There is also a new 3 ft tall septic mound that is about 10 ft away from the hedge. How will the compaction and mound affect the growth of the trees? Also, what can I do to mitigate the effects?
The soil compaction could give your trees some difficulty, but since they are already established, and since the roots on only one side will be impacted, they will likely be able to recover better than if they were newly planted. Using an aerator and taking other measures can help with soil compaction:
The septic mound is probably far enough away that it will not affect the trees' growth. However, edible plants shouldn't be planted nearby. Here is more information about landscaping near septic systems: