As I mentioned in the Hillside Landscape post, our backyard consists of a small flat area near the house and a cleared hillside that continues up into a wooded area.
Once we moved and settled into our home, we realized that the hill was actually one large Alabama sandstone rock loosely covered with a combination of weeds and grass. The dirt layer over the rock varied from a foot or so deep, to just several inches in some areas.
Ultimately our solution, after considering many options, was to uncover the rock and embrace what God planted in our backyard–a beautiful sandstone hill.
We added some attractive evergreens and ornamental plants from the Southern Living Plant Collection to surround the area and eventually create a visual link between the area below the fence and the wooded area above.
The one red flag that arose in this project of removing the grass and dirt from the rock was confirmed by a drainage expert. He warned that once the grass was removed the water would flow extremely fast down the hill and could potentially cause water issues with the house below. He suggested a major creek bed several feet deep and several feet wide. The expense and implausibility that heavy machinery could get into our backyard kept his proposal from going forward.
Armed with expert information we opted to build a smaller dry creek bed, taking fate into our own hands and saving ourselves a major hit financially. We had some peace of mind that any excessive overflow would be captured by an existing French drain closer to the house.
I’m happy to report that we have recently had flash flood warning levels of rainfall and have seen no evidence of water breaching the creek bed or any other issues. I would also theorize that the flow of the water is slowed by the flower bed at the bottom of the rock. Some of the water is likely absorbed into the bed as the rest flows along the river rock we placed at the top of the bed. Eventually the water flows out of the opening in the raised bed.
After much research and our own experience I can share these pointers for building a dry creek bed.
1. This is hard labor folks.
My husband, who has his technique for removing the layer of grass refined after many years of flower bed prep did all of the digging. I had helped a great deal with the uncovering of the rock above and was happy to let him work his magic. He describes his grass removal technique like removing icing off of the top of a cake. He makes cuts with his shovel horizontally in sections and then lays the shovel nearly level with the ground lifting the root layer of grass vertically and repeats until the desired area is removed.
Lugging numerous bags of stone pebbles to their destination in the creek is no small task either.
2. Map your course with spray paint before you dig. To create a realistic dry creek bed, add small bends as seems appropriate, while leading the water in the direction you desire. Remember to widen the creek as you create turns, mimicking how creeks flow in nature. Keep your natural slope in mind as well. To some degree the existing slope built into the backyard for run off was our best guide to the placement of our creek bed.
3. Mound your grass along the sides of the creek bed either as you go, or after you dig. This creates a “mini levee” for your creek bed and reduces the depth you have to actually dig. This was extremely important in our case, because as we guessed in some areas he had to use a pick axe to break up rock to remove obstructions.
3. The actual degree of slope required for water to flow is only 3-5 percent for the first 10 feet. My Dad who is an engineer happened to be in town during our planning process. He did some calculations and demonstrated to me what that degree of slope looked like on a level. (I don’t have a photo for you, but it the bubble was not more than halfway past the left or right line.) Here is a terrific resource for calculating your slope and creating visual markers of a proper slope. Land Grading
Needless to say the photo above is much more than the 5%. We had to dig out some sections, but after about 10 feet we had a natural downward slope with gravity working in our favor.
4. Test your creek bed. Run a hose at the top of your drain and check for any obstructions or slow moving spots. Note that after you do this, it will be a muddy mess to dig for modifications. Thankfully, at this point we were ready stop for the day.
The next day we made the necessary changes to improve flow and set out our landscape fabric. Not all landscape fabric is created equal. Invest in a high quality polyester fabric that is non-biodegradable and has the strongest tear rating.
We tested the flow one more time just to be sure. Because some of the water goes through the fabric,
I think the truer test comes without the fabric liner in the creek.
5. Cover the fabric with small stones or pebbles and fill the creek bed. We chose a medium sized pebble, Calico Stone by Vigoro. We liked the color variation and the size of the stones.
6. Line the outside edges of the creek with larger stones. Here we were blessed with a natural resource of stone. I actually doubted we would have enough stones to line the entire sides of the creek bed. I collected many of the larger stones as we dug out the exposed area of sandstone and the rest I gathered from around the yard.
7. Find a way to tie your dry creek bed into existing landscape or hard-scape.
Previously these pavers were stacked tightly two by two along the patio edge. I always felt like they were very random and didn’t like the way they looked. By spacing them in an organic way, surrounding them with the same Calico stone used in the creek bed, they are stepping stones with a distinct purpose. The continuation of the stone across the yard creates a flow that draws your eyes from one side of the yard to the other.
8. Create even more interest with large, decorative stones.
Many examples of dry creek beds I found during my research featured boulders brought in from a stone yard. Given the expense and the difficulty of getting heavy stones up our steep driveway prevented us from doing so. Eventually we may find some viable solution, but for now we are happy with what we had on the property. Not only do they fit in naturally, free is always good!
Adding this dry creek bed not only insured we would have proper drainage for our hillside landscape, but it created a visual interest and movement across the yard. This spring we will be adding more plantings to continue to naturalize the area.
As always, feel free to ask any questions and let me know if you tackle your own creek bed project!