[beaver1]

I am a do it yourselfer working on my front porch/ walkway. My concern is the area behind the retaining wall (at the left in the picture) where I would be installing pavers for the porch at the back and a flower bed at the front part. The flower bed will be sandwiched between the drainage zone and the pavers, with landscape fabric separating it from them. I will be compacting the gravel base for the pavers in stages ( every 6"), and the total height of the gravel base should be around 18" (Two more rows has still to be added to the retaining wall) . How would you guys deal with this scenario? My concern is that even if I compacted the paver base properly, in time, the front part next to the flower bed will settle and shift (I will be using paver edgers). I am thinking of somehow supporting the gravel base with some kind of a grid to hold it back, or maybe a retaining wall below grade between the porch and the flower bed just to support the porch area. I would really like to hear how you guys would deal with this.
Also, what do you think of the drainage system. The picture shows where I dug a hole just big enough to accept a 5 Gal. plastic bucket. I drilled several 1/2" holes in the bucket and filled it with gravel. A 4" PVC pipe, also filled with gravel runs under the gravel base to connect the weeping tiles to the bucket. Should I leave the bucket full of gravel open to air or cover it with top soil and sod.

[beaver1]

The picture of the drainage.

[sleepy]

Install a pump on a float valve to pump water out . Its hard to say what you need but in really messed up situations this is what you would do.
It would be better if you could daylight the pipe somewhere else. Like the street.

[Stonehenge]

Beaver1 -

First I should commend you on the base prep - the wall looks very level. Nice work.

Re: the drainage - having the top of a bucket exposed to the air is going to look funny, but more importantly, daylighting the drain pipe below grade defeats some of the purpose of the drain, as the water will always be underground, and you may get water entering the bucket through those holes you put in there. Better would have been to simply daylight the drain just above grade, notching out a block to receive the pipe.

It looks like your soil might be sandy, so it may drain all the water directly down anyway, and not cause a problem.

Re: the plant bed/paver area - your concern is justified. Building a separate wall that would get capped by the pavers (making the wall invisible would be an excellent solution, as it'd allow you to have quality soil as deep as you'd like for the plant bed and not affect the base of the paver area. Note that if you are capping the wall with pavers, the elevation of each course of block will be different than that of your existing wall.

[beaver1]

Thanks for the complement Stonehenge. I would definitely build a secondary wall to retain the porch area. as to the drainage, have a look at the attached diagram, to see if we can get away with the existing setup. The bucket is burried at least about 4 inches and all that will be seen is a round area of gravel. If not, I will try to modify it based on your suggestions. BTW, the soil here is mostly clay.

[agla]

Beaver,

Do you know how much water you will need to handle? Is there a big paver area that will drain toward the wall, or is this pretty minimum?

Stonehenge thought your soil looks pretty sandy. It looks pretty tight to me. If it does drain well, then you have the right idea to some degree. I live in a sandy place and drywells such as what you describe are very common place and often required at downspouts from roof gutters. Typically, they are larger than a 5 gallon bucket. Usually 2' in diameter and 2' deep. Some people used corrugated plastic drain pipes cut short and stood on end with lots of 1"-2" holes drilled in. Others buy precast concrete ones, or a snap together plastic kit from a home center (I think "Aquaflo" is a brand name.

Anyway, you do not put stone inside it. You put stone around it and a lid on top of it and filter cloth over the entire thing to keep the soil from settling into it.

The idea is that the "tank" holds a bunch of water and it flows out into the big voids within the stone. The wider the stone area, the more water can be held because there is a greater amount of void space if there is more stone. That holds the initial volume of water that comes into the drywell, but there is more to the story. It is the absorption of the water into the soil that counts. The greater the surface of soil that you can expose that water to, the more efficient the absorption. There is the bottom area of the hole and sidewall area that is going to accept that water. If you know the percolation rate in your soil and how much water will be entering the drywell, you (or at least someone who knows how to do it) could calculate how big to dig the hole and how much stone needs to be around the drywell. We do it all of the time.

If your soil does not perc fast, it will not be very effective. Daylighting the pipe would be the way to go.

[beaver1]

You are right agla, the soil is mostly clay. It is not very tight, but it does not drain as good as a loamy soil. What you say makes perfect sense. I might modify this system to make it more effective based on your information, or just elbow the PVC sideways and daylight it with another elbow facing towards the slope. I have a few feet of slope to play with. The patio area would be app. 50 sq. ft. at a slight incline (1/8"-1/4" /ft.), directing water towards the flower bed behind the retaining wall.
You did not comment on my other concern. If you have any suggestions on that, I am all ears.
Another picture. The retaining wall (with coping) and the front porch elevation would be level with the mid point of the existing cement porch. Coping and pavers on a bed of concrete sand would be installed on the existing cement porch.

[sleepy]

That job shure looks good frome here!

[agla]

Because it is next to the flower bed you are worried about settling. Anything you can do to strengthen the edge of your base is helpful. The wider you can go the better, although you need a root zone for the planting which limits you here.

One thing we used to do when I actually was building these things was to use geogrid in the base gravel. We did this to bridge soft spots, like over water line trenches on new houses. It will strengthen an edge as well, but you have to use a wide sheet of it (not just something skinny along the edge).

I learned this at a Keystone seminar in Spokane about 12 years ago. The instructor had a box with removable sides. He put gravel in, then a layer of grid, and then more gravel. Then he removed the sides and the gravel sat there nearly in the same cube shape as it was when in the box.

If you put a couple of layers between lifts, I think it will go a long way to strengthening that edge. Hopefully, you can go somewhat wider than your paver edge.

[beaver1]

I think I will do what Stonehenge suggested, which was one of the options I was considering initially, and agla's idea of using Geogrid. Some might think this combination could be overkill, but in the long run I look at it as insurance.
Great ideas guys. This forum is invaluable, specially to the likes of me, who do not have the luxury of the vast experience that comes from having done hundreds of projects.
I will make sure I post some pictures when the work is complete. Meanwhile if you want to keep this thread alive by posting new ideas or suggestions, I am listening.

[AZTLANLC]

Originally posted by beaver1
I will be compacting the gravel base for the pavers in stages ( every 6"), and the total height of the gravel base should be around 18"

What type of compaction equipment will you be using?

I'd be doing it more like every 2" if you are using something like a plate compactor.
6" would be too much to compact properly with a rental unit.

[beaver1]

I am using a 190 lb. plate compactor. Thank God it is not a rental, or else I would have spent a small fortune on it. I decided to buy it new, since I'm planning to build a patio in the backyard and do the driveway next year. I think it will pay off in the long run. As to the depth of compaction, even though the manual states it is good for 12 inches, so far I have compacted in 3"-4" lifts with good results. I also have a Wacker ground pounder (jumpin' jack). Do you think using the jampin' jack initially and finishing off with the plate compactor works better?

[beaver1]

The following are some pictures of work in progress, and the finished project. The landscaping part has to wait untill next spring. Below, it shows the retaining wall to support the patio behind the planter. Also, notice the geogrid in the background (I know, the image is a bit blurry). Two layers were installed, every two raws, covering the whole area and overlapping the retaining wall.

[beaver1]

Work in progress.

[beaver1]

The Hardscaping part is finally over. We had so much rain in October that for a while I thought I would not be able to finish. Next spring I'll do some landscaping to finish it off. There will be a lamp post built with Brussels Dimensional stone, where you see the pile of gravel - the conduits are already in place. Just behind, where the planter wall meets the stairs I would be installing one or two Landscaping stones on a bed of river stones, either Mica stones or Belmont rose. In the foreground, where the backside of the coping is exposed, another planter extending from the lamp post and finishing at the driveway. Finally some shrubs, flowers and trees to dress it up. Eventually, I,ll finish the driveway to blend in with the half moon.