I do admire your idea about replacing English Ivy as this groundcover not only attracts rats but can flower and make seeds if allowed to climb trees. Then the seeds are spread by birds and the invasive English ivy goes on to smother our native forests. I do think if you keep your ivy neatly trimmed and never let it escape or flower you can keep it safely in place. If you want to make the big effort to replace it then consider Cotoneaster Lo-Fast, weeping evergreens and low growing junipers or even a display of the native evergreen huckleberries, salal and sword ferns. A section of fencing to screen the tanks from view with planting in front is also an idea. Good luck and thank you for reading the column, Keep growing, Marianne Binetti