Levelling bumps on a grass airfield

[xrayalpha]

Hi,
Might be coming into a windfall in a wee while, so anyone know of people who have successfully levelled ground for a grass airfield.
Looking at some substantial wokr, with ground level differences of up to 2ft over 200ft having to be levelled.
Needs more than a few handfulls of sand in the dips!
Have heard of some experiences, but would like to know as much as possible.
Concreting is not an option, the field is not boggy either, so no need for Perfo etc.
Soil is thin, undernearth is whinstone rock (can dig it with a JCB).
Thanks, XA

[Pilot DAR]

I have struggled with this for the 22 years I have had my runway. If winter freezing is an aspect, there are added complications.

The best solution, which I have done on nearly half of my runway, is to plough it up (farm field style), and grade it back smooth and level, with a crown, and ditches both sides. This will produce the best result. If that is not possible (rock close underneath), bringing in loads of soil will be necessary to fill the low spots, then grade that in. To be effective, the machine used to grade the soil must have the blade midway between the front and back wheels. Though it is possible to grade with a front or rear mounted blade, it is very much harder to get the ground level. The friendly farmer will tell you he can do it with his blade on the back, or back dragging the front bucket, but you won't be happy with the result. You'll know you've got it right, when you very happily drive an expensive low slung car back and forth the length at 100 KMH.

Different aircraft types will handle rough ground differently, with high wing singles generally being a bit more forgiving, and some more than others. Over the long term though, even though the plane might handle the bumps, it is still hard on the airframe. Better to fix the ground first, that the airplane later!

Pilot DAR

[Lister Noble]

I think there may have been several posts on this a couple of years ago.
Lister

[matspart3]

We took a few of the ridges out of the 300m grass strip at Gloucester with a JCB and filled in some of the troughs with what we took out. We've also rolled it a few times with a vibrating roller and don't use it when it's really boggy.

The only real solution is to plough it up and start again. Depending on when you do it, it'll take 4-6 months before you can use it.

[Oldpilot55]

Craig Jones, the local autogiro guy, knows a thing or two about levelling grass strips.

[Lister Noble]

Best thing is ask a local agricultural drainage contractor to have a look,get a quote or two,and get him to do the job,might cost a few grand but worth it in the end,or buy a helicopter:}

[jonkil]

http://www.pprune.org/private-flying/252864-setting-up-strip.html

http://www.pprune.org/private-flying/356493-making-grass-strips.html

[rogcal]

I looked at getting my strip levelled a couple of years ago and was quoted 3.5k just to do 300m of it.

The company that quoted for the work guaranteed a level surface and when I looked at the kit they were using (everything lazer guided and two hundred and fifty grand to buy it) I could see why the job would cost so much.

Decided against it in the end (not enough pennies in the kitty) but if I came into a windfall I'd get them on the phone tomorrow.

[Cusco]

The farmer drags a ruddy great roller up and down our strip at the end of the winter/early spring: Does the job a treat and repairs the damage caused by local chavs donutting all winter.

Grass can be so forgiving...........

Cusco:rolleyes:

[xrayalpha]

Hi,

Got any details of the firm.

I think we may have 10k in the budget now for next year and I would have thought a proper job for the whole airfield could cost 30k.

Even just to talk about how they might do it.

We are talking earth-moving here, not just squishing down some ruts with a roller. If the ground was that soft, we wouldn't be able to fly off it!

(Never lost a day yeat due to waterlogging, with three school aircraft and club members, and want to keep it that way - but also want the h/bumps removed)

[robin]

Any chance Compton Abbas might be reading this.....:ok:

[Zulu Alpha]

The farmer drags a ruddy great roller up and down our strip at the end of the winter/early spring: Does the job a treat and repairs the damage caused by local chavs donutting all winter.

Grass can be so forgiving...........

Cusco

Doesn't get rid of the bump where the extension was added despite multiple rollings in each direction.

A friend levelled his strip by hiring a turfing machine to remove the turf, then he used diggers etc to level it and then put the turf back down again.

ZA
(soon to be DT)

[Cusco]

Doesn't get rid of the bump where the extension was added despite multiple rollings in each direction.

If your wheels go over the worst bit then your wing is in the trees...

It's a minor problem.

Cusco

[pulse1]

Robin,

I don't know when you last went into Compton Abbas but, if anyone wants to know how to level bumps, they are the ones to ask. They proved that they know how to do it a few weeks ago. Last big bump - gone.

[mikehallam]

Field Bump levelling.

I learnt they use a laser to level golf greens & thought of the difficulty we had altogether trying our best to shift thin layers of soil & turf in the middle of the Jackrell's Farm strip a couple of years back to lessen that old ditch bump half way down. However with a cheap laser level I already have, it could be set up with a guide stick to check it out, one day early this coming Spring.
i.e. Get a bead on the ripples we can't otherwise see, but do feel, & smoothen them out by moving soil or turves a wee bit ?

[IO540]

I know nothing about this but heard that a strip which has been flattened with a heavy roller is liable to waterlogging because the water cannot soak through the surface.

No idea if this is true :)

[Agaricus bisporus]

XA, with 2ft undulations to be resolved I'd think that a full sized grader is required. Is there a big road-building or industrial unit bullding project nearby? If so find the earth-moving foreman and explain your interest in a smallish hire job when his machines aren't comitted...

You just might strike lucky, and even for a few grand it'll save in time and effort over struggling with JCBs for weeks at little less total cost. You're talking a huge job for JCB type equipment, and even if it can shift the volume it will neveer get it flat, as said above. Do it right first time.

[doubleu-anker]

Make a homemade grader from an old set of uniform sized tyres. Set them up in a "A" frame, starting from the front 1, 2, 3, 4 and 5. 5 rows and 5th row with 5 tyres at the rear. Wire them together. I have instructed strip constructors/keepers in Africa to use this. Works a treat but it has it's limitations of course. The ground must be dry enough to support the towing vehicle and soft enough for the earth to move. It will not plane off large ridges. Just keep going up and down the strip for as long as it takes and I have seen and felt some surfaces as smooth as a billiard table after this treatment applied in the correct manner.

[jonkil]

When I did mine I used a 36 Ton Kobelco track machine. No good hitting it with anything lighter. I was lucky from the point of view of having access to this type of plant, hiring it in will cost approx £150/£190 per hour, but it will get the job done. Levelling can be done with the laser on the outer jib, no problem.
You should be able to get a quote locally from any good contractor that does farm work, many here in Ireland.
Rolling a grass strip with a heavy roller is a disaster, you compact the upper layer of soil and wreck the natural drainage. Slit draining with pea gravel will help any drainage issues but a good collector drain/sheugh is needed first.
Can PM details if required.

Jon

[Cusco]

Rolling a grass strip with a heavy roller is a disaster, you compact the upper layer of soil and wreck the natural drainage.

Depends on location and subsoil:

Our strip is on the site of a WW2 USAAF airfield carefully chosen on the highest ground for miles around with a well draining sandy/gravel subsoil.

The rolling smooths it out a treat, helps repair the divots taken out by the chavs in their Astras and makes absolutely no difference to the drainage.

Strip is flyable all the year round even after the heaviest of downpours.

Except right now when its under 8 inches of snow.....:ugh:

Cusco.

[rogcal]

XA, I've PMd you.

[Zulu Alpha]

Doesn't get rid of the bump where the extension was added despite multiple rollings in each direction.

If your wheels go over the worst bit then your wing is in the trees...

It's a minor problem.

My point is that rolling doesn't remove bumps, even small ones. It is good at removing molehill, and car skid marks but you need to remove the turf to get rid of any bump you can feel. I believe that you can fill in small depressions by adding soil gradually so the grass grows through.

Personally I don't use the extension as the bump is large enough to launch me in the air at just below takeoff speed

ZA

[pa28r driver]

i agree with pulse,i operate out of compton and they have done a bloody marvelous job at the east end. (and they did it in two days )
regards to all
pete

[robin]

That's great news.

For years I've had lots of my beautiful landings turned into hideous bounces, so will be looking to give CA a go as soon as my baby is back from the menders - 16 weeks and counting!

:ugh:

[astir 8]

If you are talking a 2 ft level change - even if it's cut 1 ft, fill 1 ft, it's serious civil engineering machinery territory. There are lots of big boys toys hire shops if you want to try DIY - an excavator with backfill dozer blade and a dumper truck would be the minimum kit but it would be slow & messy.

A professional outfit would be the choice if you have the money, and preferably if they are going through a slack period and need the work. Otherwise you'll mainly be competing with people who have taxpayer's money to burn.

Points to note - specify that the turf & topsoil must be stripped & stored separately for replacement after levelling - it's the subsoil you need to move to the low ground, not the topsoil or the grass will never grow properly again.

Compaction of the fill also needs careful specification. All the laser levelling gear in the world is useless if the filled area is left loose as it will settle severely over 12 months or so. A guarantee that the company will come back to rectify any settlement would be good.

Enjoy!