View Full Version : New Landscape Drainage Issue
01-29-2012, 12:49 PM
I'm dealing with a drainage problem and would appreciate some feedback.
In a new residential landscape we installed in the fall of 2011 a drainage problem had reared its ugly head.
The main yard is a raised area that is retained by a pored concrete wall, faced in cultured stone. The areas where the new turf meets the bedding has started collecting water and there is a 4-6 ft. wide area of the turf, all along the bedding lines, that collects water like crazy. Unlike all the rest of the turf we installed in the other areas of the yard that are looking nice and green and lush, this area just won't drain properly. At one point, we even witnessed upward bubbling from the turf in few spots where there is standing water and in two other spots there was air trapped under the turf causing an actual air bubbles! I've only seen air bubbles under turf one other time in my 20 year stint in landscaping and that was in a commercial area where there was known methane coming from a re-developed landfill site. However, when I cut the bubbled turf with a sod knife, there was no smell of methane and there have been no air pockets develop since, and that was two months ago.
We're going to be tackling this drainage problem in 10 days when the property owner is back from holidays. I think we're going to go in and dig a drainage trench right through the middle of the waterlogged area, do a drain system with perforated pipe, fabric, gravel, etc. and "daylight" the drain through a low point in the poured concrete wall. Top the drain/waterlogged area with a 60-70% sand mix and re-turf the area.
Also, I'm going to spend the extra couple of hours it's going to take and remove the plants from the bordering bedding areas and give the beds a good tilling and here's why... In going through some video footage that was taken when i was off-site and the soil was being installed, I noticed that one of the guys was using the bed line as his repeated line of delivering buckets of soil to the planting beds. He was using a Bobcat MT-52 track machine and even though the beds are 16" deep with nice composted topsoil, I've noticed some of the more sensitive plants struggling. When I tried to put a shovel in the flower beds where he was running the machine, I struggled to dig a 1 gallon size shrub hole. I'm sure the compacted soil bordering the turf hasn't helped the drainage of the turf, either.
I've checked back on some pics I took of the finished subgrade and all my drainage patterns look good.
I can upload a couple of pics if that would help. Anyway, that's my plight for the week. Any thoughts?
01-29-2012, 02:02 PM
You need to post picture's.
01-29-2012, 02:16 PM
Barry, it sounds like you need a sump and a French Drain unless you can somehow daylight a drain through the retaining wall. What a PITA.
01-29-2012, 05:38 PM
Here's 2 pics...
You can see that the subgrade preparation pic shows positive drainage toward the irrigation boxes. The other pic shows the retention of excessive moisture where the bedding meets the turf.
Walking off the sidewalk, on the turf, is fine, but the further you get towards the bedding, the wetter it gets. The thing that's throwing me off is the bubbling and air pockets under the sod that I mentioned in my original post. I was suspicious of a problem within a few weeks of installing the turf because the turf never did reach a nice deep green color, even after fertilizing.
I'm thinking a drain line (french drain) coupled with sightly raising the grade with sand and new sod over the effected areas should fix the problem. I'd rather overkill this situation and be done with it as that's usually my approach. The good news is this customer is very happy with our services and has confidence in us. He wants on-going maintenance, lighting, water feature, etc. In fact, i'd like to clone him! The reason for posting here is to get a meeting of the minds and make sure I'm not overlooking anything.
Any thoughts? Also notice the plants that are stressed from water, too, like the 3 or 4 Taxus. Btw... the beds have been weeded since these pics.
Now, I'm heading over to the equipment forum and look for a cloning machine...
01-29-2012, 07:02 PM
That look's like a sump unless you can get out of that yard. I don't like sump's in this area because the clay is too deep.They just turn into big wet spot's. But it can be done if your soil is right. Do you know what the soil does 10 feet down ?
Don't let those turf bubble's bother you. That's natural. I have seen what look's like a water bed under the turf because of the rain. The water move's between the (around here) clay below and about the top 2 inch's of grass. I have also seen little bubble's caused by rain forcing air out of the turf.
01-29-2012, 07:30 PM
That basalt stone you see in the middle of the pic is marking a small rock pit I dug about 2 months ago, just to see what would happen. I thought about digging it out really big and doing a sump there.
Right across the concrete walk to the left there is another bed with a huge downspout sump system for the house with a pump system in it. I wonder if I can get under that walkway with a connecting 4" PVC pipe.
Anyone ever undertake getting under a walkway? It's about 4 ft. wide. I've seen irrigation companies do it.
I'm still thinking on raising the finished grade with sand and new turf along the bed lines.
No luck on the cloning machine yet.
01-29-2012, 11:13 PM
Going under a walkway is easy. Just don't leave a void that will cause it to break.
01-30-2012, 04:55 AM
Actually, I messed up... The sump is located on the other side of the walkway to the right in terms of this pics orientation. You probably figured that out already, though, lol!
What do you think about also raising the grade of the wet areas with sand and new turf. The irrigation system will protect turf in times of summer drought, and, here on the West coast of Canada, we get PLENTY of rain in the fall/winter months. Ot at least a soil mix with about 75-80% sand?
01-30-2012, 03:51 PM
I knew something wasn't right with that picture. I don't think raising the grade will work. That soil will just act like a sponge and won't dry out. You need to fix the drainage right the first time so you don't have to mess with it again.
01-30-2012, 07:52 PM
I'm still wondering what the actual cause of the drainage problem is. It must have to do with the fact that the builder didn't install drainage behind the poured concrete wall and the subgrade isn't draining as it should. My drainage patterns seemed good before I installed the soil. On a rainy day before we installed the soil the water didn't sit in those areas.
The soil installed was a composted bedding mix for the planting areas and a 65-70% sand mix under the turf.
I'm hoping this drainage line we want ti install is the answer. I only want to to this once!
01-30-2012, 11:36 PM
Well, i would have installed a smile drain in the subgrade all the way around the outside edge that walkway. It look's like everything slope's toward's that. Any free water is moving between the subgrade and what you filled. I'm sure that contributes to a wet situation. Was there any heavy equipment used in that area? That will cause compaction. What about irrigation? H.O.'s are bad about overwatering. It look's mighty wet.
01-31-2012, 03:45 AM
The only piece of equipment we used in there was a Bobcat MT52 mini track loader. Only about 1200-1600 pounds. As mentioned before, my brilliant operator did repeatedly run the machine on the bedding areas during his trips in and out of the area, compacting the bedding soil something fierce! Getting a digging spade into the topsoil in the planting bed is a real chore, now!
Since the wettest areas are where the turf meets the bedding, I think this must be contributing to the lack of surface drainage. That's why I proposed removing the plants and tilling the bedding soil to loosen things up top, as well.
I thought that (loosening up bedding soil), along with running the french drain system under the turf through the wet turf areas, close to the bedding, would be the answer. Then, terminating the french drain in the large sump on the other side of the walkway.
As far as overwatering goes, the longest the timers were set for was 5 minutes, and the system was blown out and winterized in late October 2011. Although, the Vancouver area of Canada, where we live, is a very wet, mild climate in the winter months.
01-31-2012, 11:22 AM
My thoughts are .... deal with compaction before you start planting. :)
01-31-2012, 12:59 PM
That's what I get for taking my eye off the ball and letting my "foreman" have a little too much room to think. If I've learned anything in the past 23 years of landscaping it's to hire good people, but never take your eye off their work completely. After all, if the inmates are allowed to run the asylum, only bad things can happen.
Basically, it's my fault for allowing it to happen. I'll install this drain system, finish the job, accordingly, learn from my mistake, and move on.
Thankfully there are good customers who have faith in my abilities. And, thankfully there are thee forums to bounce ideas off other, like-minded people.
01-31-2012, 01:30 PM
The importance of proper soil preparation cannot be understated.
01-31-2012, 02:00 PM
Definitely. It's like building a house on a bad foundation. And the funny thing is, I know that! I knew things went south when I came back to the site to do some additional planting, the next day, and the soil was so compacted that I had to jump on my shovel to make a shrub hole.
Needless to say, said foreman is no longer with us!
01-31-2012, 02:04 PM
I knew things went south when I came back to the site to do some additional planting, the next day, and the soil was so compacted that I had to jump on my shovel to make a shrub hole.
That warning flag should have knocked you over.
01-31-2012, 02:13 PM
I'm sure digging the trench for the drain system should help in the "knock me over" department. Then, till the beds and top them with some fresh, finished compost and we should be back on track.
At least that's what I'm telling myself!
01-31-2012, 02:29 PM
I recommend you pull some soil cores to establish how deep the compaction goes and/or use a penetrometer to map the sites soils.
01-31-2012, 03:42 PM
The wet area(s) of this property are in a very specific area. I've established that the wet area(s), where there is actually standing water in the turf, and the wet bedding that borders said turf area(s) are also areas where the plant material is struggling and not responding to nutrient. The other areas where there is drainage are functioning normally.
I thought listening to what the landscape is telling me would be the way to go.
01-31-2012, 03:45 PM
I have a manual soil probe that pulls small, 1-2 inch cores from the ground. Is that what your suggesting?
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