At my best I was in the pool at least 3 times a weeks, sometimes used as a morning. I felt as fit using the pool but fresher and not tight from running. Was good as a recovery run but used to run a really hard session in the pool once a week. What about this for training, high volume week.
Mon am 30/40 steady in pool pm run 50/60 sub 6 min miles
Tue am 30/40 steady in pool pm run 60 inc strides/drills and 20 mins @ 4.50/mile - tempo running.
Wed am 30/40 steady in pool pm as monday +30min weights
Thurs rest day
Fri am pool 60 mins with 4 x 6 mins hard/1 mins rest
Fri pm steady run 30/40 mins
Saturday am 30 mins circuit training pm 90-100 mins east
Sunday am 30 mins swim
sometimes ran a tempo run in the water and the session such as 4x6 mins on the ground. Perhaps 2 hard sessions on the ground in the spring to get legs moving for the summer.
Probably not totally normally but it got me 28.30 for 10k on the road and close to 4 flat for a mile.