The area you are talking about is relatively small. The roots of mature trees extend well beyond that area in all directions. You're never going to get a guaranty about the effect of grade change on adjacent trees any more than you can get one for a heart transplant. Pay your money and take your chances, but they look good to me. It looks like you're only in need of something rustic to retain soil, so boulders (if they're big enough), fallen logs, RR ties, timbers, segmented blocks... whatever you can stand and your budget will allow. It looks like your house is above the area so you will not see the "wall" itself, making the material somewhat inconsequential. Some play sets may allow grade variation so explore that before you regrade. You might not need much grade change.

Thank you for the reply and guidance. I read a few articles stating changing the grade near oaks can cause damage since roots could be shallow. I would only raise the grade on one side of the oaks- but still fear I will be impairing water absorption.

It would be an expensive experiment. In my area, the cost to remove seven 50' oaks is probably as much as a heart transplant these days.

I can't offer any advice about regrading but did want to share what we did when installing a playset In a sloped yard. We went with an a-frame style and purchased one side to be a larger height than the other to accommodate the slope. This let us get an upgraded higher height set and it fit our yard without regrading.

Good luck with your project!
Michelle

Large boulders + children's playset = not a good feeling.

Karin L

"the cost to remove seven 50' oaks is probably as much as..."

You wouldn't be affecting all trees equally. You might be surprised to learn how distant from the main trunk a tree's roots travel. It correlates to the height/size of the tree in a 360* pattern. You're not cutting roots, ending their activity at the cut. You're adding soil to a relatively small portion of the area they occupy. The vast majority of the tree's roots will remain undisturbed. Many of the roots beyond the zone of disturbance and the 9/10 of them outside of it will continue to function as before. If you were adding soil all around the tree in a wide band, the prognosis might be shaky, but here I don't think it is. I've seen trees survive many times worse treatment than what you're proposing.

As always, especially in situations like this where there could be some potential big buck problems created , it would be best to have an on site consultation from an arborist. The cost will be very small in relationship to the peace of mind.

You might also enjoy picking up either Sunsets book on outdoor playstructures or Taunton Press " outdoor idea book. Both have some great info about placement of structures and the desired open space requirements around a structure for safe playing.

Also , I don't know what kind of play surface that you are going to place under the structure but if it is playground fiber , which I feel is a lot more comfortable than just regular mulch, you need to dig down about 9 to 12 inches for a safe surface. I know that sounds extreme and this depth is in direct relationship to the height of the potential fall zone, but the deeper the better for shock absorption.
Again, the Taunton Book has some great info and nice examples of play structure set ups for all different types of uneven grades.

photo of a playstructure built into a retaining wall

That's such a nice photo! I was about to ask, what about a tire swing on an existing oak, and a ladder up to a tree-house with a slide down... Good luck with your project!
Suzi

A slight tangent on the same topic .... night and safety lighting around a kids play space.

A lot of the times we see path lighting around a kids play area that is just begging to be accidently knocked over or mangled by a wayward bike . Most of these light fixtures are a 'bulb on a stick' or a 'lamp in a can'.

I found that Hadco makes a really tough fixture that can be ground or column mounted. They look like mini light houses and they are tough as nails.
The fixture in this photo is about 15 years old and is located in a back yard that has seen a lot of kid action in its years of service.

I originally saw these used on a dock in Sausalito CA and thought that if they could handle the salt air that they would do well in a foggy area up on Mt. Tamalpias. They weren't cheap but when you consider that they are easily going to give 20 plus years of solid use , they were worth the initial investment.

Appreciate everyone's input and suggestions. Very kind of you all to offer guidance.

Really liked the idea of using existing structures with a playset- amazing picture DD! Also appreciate the lighting suggestion. Never even considered adding lighting.

Assuming I could dig down 9-12" and regrade the area by reducing the high side by 12" and building up the low areas. This is something I am now considering. Just need to figure out how to frame out the area for the mulch.

I have a tree expert coming tomorrow to assess the area and get a quote on plantings and grading. Our township denied my application for a fence permit since one side of the proposed fence falls within an easement area. They did approve planting of trees to stabilize the bank but now denied the fence. So I will just add some type of plantings and regrade without adding a fence. Will look to add a fence later when I have the energy to argue with the township.

I am starting to think Michelle's suggestion for purchasing a playset that can accommodate a slope would be the easiest solution. Only playset company I found that could be altered for slopes was Rainbow sets-I still have to level out area for the clubhouse but that is only a 5x5 patch.

We still want to fix the sloped side of the yard to make a more useful play area. Will let everyone know what the landscape contractor / tree expert proposes.

I think you will find that working with the folks at Rainbow Play structures will be a good experience.
We've worked with them on about a dozen of their play structures and they have always been helpful.
I especially like their method of recessing their bolts and doing the little extras that make a structure safe.
When we have had problems they were Johnny on the Spot to come out and adjust or replace an item.

On one of our projects I donated an old computer keyboard to a playhouse and they set it into the wood railing and screwed it in safely for no charge.
A nice little touch that has earned my loyalty.

I'm also crazy for Barbara Butler's play structures. She will custom make anything but they are quite expensive. A great website to glean ideas from.

Here is a link that might be useful: http://www.barbarabutler.com/

Thanks again. Barbara Butler does have some wild designs. Definately expensive but provides some really interesting ideas.

Landscape contractor proposed just adding clean fill and top soil, compacting and seeding. Also add some plantings to the edge of the area. Will this hold the soil?

The stream is never high enough to touch the proposed leveled area, but wouldn't the rain cause eventual erosion of the soil?

He agreed the leveling would not harm the pin oaks.

Thanks again.

"Also add some plantings to the edge of the area."

It's the plants at the edge that will stabilize the soil and keep it from washing away, but obviously, when they're new, there's a period of time before they will do their job very well. Select plants with this job in mind. Groundcovers seem like the category you'd be most likely to look for.

Check the last two sentences of my first post.

Yardvaark - truly appreciate the advice. I just reviewed the ground cover forum and will post for actual planting suggestions.

This is one of 5 landscaping projects for this year... My yard has been neglected since the kids came along...

Thanks again!