Expert Guide to Proper Drainage to Avoid Flooding in San Diego Yards

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  • Post last modified:February 9, 2024
  • Reading time:8 mins read

No one thinks about drainage until it rains very hard leaving little lakes around the back of the house or down the side yards. In fact, Southern California doesn’t get much rain during the summer but when it does rain, it comes down just as hard in the Winter for a short time as it does in much of the country.

California is a desert state and many of the soils are ocean bottom or a base high sandy clay. This means that the absorption rate of water can be good in some areas and not so good in others.

In many newly developed tracts around San Diego, most lots are sloped towards the street to prevent run-off from going into the neighbors-property down below or from side to side. Usually the water makes its way to the street and the waiting storm drains located there.

From the street, the heavy run-off can then travel by large storm pipe to a lower running river or be piped straight to the ocean where the run-off mingles with the saltwater and goes back to the sea.

This system works well in most areas but sometimes a low-lying backyard or poor drainage can interrupt the cycle.

Most good Landscape Contractors tilt the new concrete patio away from the house into surface drains in the planter areas or dedicated soils. Creating a cupped area with a drain in the middle of the concrete often creates a wet pooling area or collection basin that can back up from any roots infiltrating the drainage pipe 30-40 ft. away.

Using a snake or a wire fed drain clearing device can work in the initial stages of new construction but the thin wall of the drain pipe, usually a plastic material will break when faced with a high-speed drain snake or a wire feed traveling at high speed into a 90-degree turn.

Glued joints and solid pipe are the best for keeping roots out and clearing the pipe is best accomplished using a garden hose with full pressure water. This helps lubricate the hose, liquifies the mud or soils and removes many of the blockages that occur over time in the drain pipe below grade.

Sometimes, the soils are so clay like that the concrete color will mottle if the concrete is cupped to capture run-off in the concrete. This happens because the water in the concrete and soils becomes trapped and will not run off under the concrete to the planter areas as recommended.

The best way to install drains in a landscape is to think 15-20 years down the road. By installing the pipe in the soils, this can be removed or cut and cleaned out without much difficulty because it is not underneath the existing patio space up above.

Drains should always be installed with the thought that they need to be replaced in the future and concrete is better cut, because of cost, than removed in order to install a new channel drain or a new pipe drain in the planter areas that have been dedicated just for that purpose.

New drainage is always easier to replace with a little bit of digging than it is to remove concrete and replace it.

Channel drains are a good solution to a poorly poured patio. Many times, the patio is sloped the wrong way or the drains are blocked due to palms or trees that have grown up over the years.

Tray drains can circumvent all of these problems because they are set lower in the concrete than the existing drains, they are readily access-able to the home owner to be cleaned out in the future and the newly cut channels do not require a back fill except for the drain itself and its top cover or plastic grate.

Setting them at grade still allows the water to run out into the storm drain down below and removing any sediment from the tray drain is an easy task that can be done using a high-pressure hose at one end of the drain while checking for sediment at the other exit.

One very important thing to remember when saw cutting in the new tray drain is to lay out the plan first from drain to drain in the concrete and then to make sure that it exits into the surrounding planter area with a glued together pipe. This will guarantee the proper flow rate of collected water from the storm water collection basins in the patio and allow it to flow by gravity out to the street where it can be picked up and taken away.

Most city engineers are trying to create collection basins on site around new homes to get the water that has fallen on the roof and the outdoor patios into the surrounding soils. The only problem with that is that during a 100 year or 500-year rain event which are now becoming more and more common, the soils have become so oversaturated with water that it cannot be absorbed before it begins to pool or pond onsite.

This leaves the designated bioswales unused and creates another run-off stream to be dealt with.

Over flows are very important to the home owner. When it rains so hard that the existing planter areas cannot accept anymore run-off, the drains should be placed to remove the excess and to take it away before it damages the home. A drain pipe should always be routed to a pit or bio-swale lined with plants to allow for the absorption of this excess run-off.

An excess water pipe with a grate on top of it should be installed near the top of each bio-swale. These relief valves are specifically designed for the eventuality of too much water being dropped from the heavens at one time and prevents sediments from clogging the water way as it leaves the property.

Remember that downspouts are still part of the drainage system and will have quite an effect upon the surrounding flora and fauna over time. It has been my experience that an older home can have tree roots grow up the drainage pipe so prolifically that they can actually be found growing out of the gutters along the top of eaves in an older home.

Not only can this stop the proper drainage from occurring and occlude the drains whiles preventing them from working, but the saturation from the roof during the winter can damage all the walls and stucco surrounding the wood in the house construction and cause damage that would never have occurred otherwise.

Removing the drainage down below and installing a new system that works well will prevent this from reoccurring in most cases. Removing the climbing roots from the downspout is imperative but preventing this from occurring once again can be accomplished by using a good SDR35 glued in place drainpipe.

This type of drain rarely breaks or cracks due to root incursion but mother nature can always find a way and it is always a good idea to inspect or check the flow on your drain system every couple of years.

When planting a new landscape, always remember the old adage. Less is more. Trees, shrubs and small plants should be installed sparingly and irrigated using drip line with a dedicated emitter.

Water pipe used in the case of a large tree can be wrapped around the larger specimen in a loop with several emitters being used.

This allows the larger specimen to get the required water it needs for good health at the same time as the smaller plants can get what they need without overwatering. Drip helps drainage as much as it prevents weeds, the loss of water and helps keep the drainage system intact and functioning properly.

If a landscape is designed properly, shade, the movement of the foliage, color, irrigation, hardscape and the implementation of proper drainage can all benefit from one another in a symbiotic relationship. Just like all things, proper maintenance, the care of the practiced eye and the understanding of how things go together for the eventual benefit of the landscape are key to this science.

From my short time here on the planet, no design or install is perfect. There are always going to be problems with some of the plants or the maintenance that comes with them. The best designs are those that take into account the issues that need to be corrected before they become problematic.

Small plants and adding mulch to a group of the same type of plants is part of the joy that comes from gardening. Being pragmatic only carries you so far. It is the working with and the understanding of nature that makes a landscape so wonderful and a beauty to behold.

Being aware of the intricacies and the subtle changes during the seasons as well as how things work together whether they are drains, irrigation or the beauty of plants is truly what makes gardening fun and exciting to enjoy.