Good question. An acre is a big job. Aeration may not help. Not much fescue around my town. However I suspect that the bumpy character of you lawn is due to "fescue clumping". After a few hot dry spells... turf type tall fescue might get thin. During recovery it does not spread, except the remaining individual plants tiller-out and get bigger--unless--the seed included rhizomatous fescue. Do you remember exactly what varieties of fescue were sown originally?
But I am in Michigan not much fescue here.
Possibly if you could add bluegrass to your mixture the rhizomes of bluegrass would spread out and fill in to form a tight turfgrass.
Perhaps talk to your local seed dealers. Ask for the full story on rhizome-forming fescue.
Maybe rhizomatous fescue seed would help. If no irrigation, a late summer seeding would take advantage of favorable weather. Say about 6 weeks before frost.

 

Thanks for the answer. The bumpiness is caused by a few things. I’m on a hill so there has been some erosion. Also tree stumps got taken out so some roots have rotted. Our neighbors did about 100yd of sand over 5 years.

 

Is sand a good medium for this purpose/function? I can see top-dressing washing away on a hill, however...so...

 

All I cut and plant is fescue or bluegrass but mostly tall fescue. I wouldn’t put sand in it at all. If you want to level it out bring in some good topsoil

 

I would not add sand either in this part of the country. You will need to use enough just to level the ground that you will certainly be creating layers within the rootzone.
Add topsoil or aerate the crap out of it and drag it each year to break up the plugs and get the loose soil to fill in the low spots.

 

I was thinking to dethatch, aerate, scalp, seed, fertilize and dress with sand. Am I trying to do too much in one go?

No, your are NOT doing too much in one go. In fact those steps should ensure best results. I would change the order of the steps slightly and add one other step:

1. scalp
2. dethatch (and remove thatch)
3. aerate
4. top dress with compost/topsoil
5. seed
6. backdrag seed into top dressing
7. fertilize once you see germination

 

You could also just slice seed, which in turn would remove steps 2, 3, 4, & 6. WARNING: slice seeding (as is power raking) is very aggressive on existing turf.
Whichever method you choose, don't skimp on amount of seed you put down. Seed as if you are seeding from scratch, not overseeding.

Check out this thread and look at posts #12 & #13 where I provide some good YouTube video links:

Overseeding

What is everyone charging for overseeding nowadays? Looking for input on labor only. Hopefully the cost of seed will be coming down soon...

www.lawnsite.com

 

At first I was thinking bumpy. Maybe it has been cut the same direction too many times. That the weight of the mower made tire groves. Cutting when soft. Then I see it is from washout on a hillside. With some areas where a tree stump was. That sunk when it settled.
That says to add topsoil to them spots.
To fill in the bump.
As far as being concerned about the thickness of the turf.
If it is thin that you see soil.
& you get snow , thaw, then freeze.
You can just over seed it . Before the last snow. To get seed to soil contact. Using nature. I also agree with Riggle.
On the kbg. As the overseed.

 

Thanks, lots of good advice. I will indeed do it early this year. In the past I had waited until the growing season but I realized after planting some seed in October which grew out fine, that if you seed a bit too early it just stays dormant until temperatures rise.

 

Only time I have used sand. Was where the soil was spongy. I just threw the sand out by hand. To not mash down any of the turf. I just wanted to stiffen the area. Keep in mind that a chemical tech doesn't like winter seeding. That it takes away the prevent application. That stops seed from growing.
Only time I do not like putting seed down is between March - August.
That you need a good 6 mowing b4 the summer heat.

 

Why would you scalp it?

That does nothing to help the bumps.

It does harm the existing turf. Cool season turf should never be scalped.

 

Just curious but have you considered rolling the lawn. Yes it will cause compaction but may help with bumps. Must be a heavy roller to do anything. Then aerate after and seed. You can always level it all out with a box blade and and start over. Honestly there is no such thing as a flat lawn.

 

I do have a roller - 48". I will say that when it's full of water, it weighs 1200lb, which is terrifying when pulling with a 1000lb tractor on a hill. I have used it to level things a bit in the past, especially when I put a new drain in and did some regrading. Guess I can break it out and give it a go before aerating, it won't cost anything.

Of course no such thing as a flat lawn, especially on a hill, but flatter would make a big difference, as there are big dips and holes which make mowing the lawn a jarring experience!

I could level it out with a box blade, but then I've got to pray we don't get a serious storm. I did a bit of that last year when I removed a very large 60" tree stump, and of course it then settled a bit and I'm back where I was!

 

Put some thought and careful planning into this project. The soil will be soft and pliable when it is wet. Maybe even more soft when the frost in the soil is melting in spring. In some cases, your feet will be able to smooth out ridges and bumps. And a heavy mower will smooth out bumps and mounds with its tires, in spring. Of course--this summer you can use a hose and sprinkler to wet down the soil--this to make it soft and easy to work. Maybe you can use a garden fork or spade to lift low spots when it is soft.
If you have no other choice--pull back sod--then add some topsoil.

 

Scalping a cool season species?
No way.