Westside & Portland drainage. With DIY tips.
Estimates available (after consultation)
Copyright 2004 - 2012 by Mario D. Vaden / Header context: Largest Coast Redwoods
If you need an estimate for installation of a yard drainage system or French drain in the Portland area, please see the contact page, and review estimates.
Before deciding about estimates and consultations, be certain to scroll down this landscape drainage page and find the photo of the root growing through a Portland area drainage pipe ... installed by another licensed landscaper. The root in the drainage pipe is just one of a few things that were wrong, and about 1 year later we replaced that inadequacy with a new drainage system and entire back lawn. This drainage stuff can take a lot of experience to decipher, and there are quite a few landscapers who have not been weaned-off-the-bottle yet, who try to re-translate "inexeperience" as "experience" with their landscape license.
We help home owners near Portland, Oregon, westside including Beaverton, Tigard, Sherwood, Wilsonville, Hillsboro, Tualatin, Lake Oswego, West Linn and Tualatin with advice or improvements. With every 100 sq. ft. of local ground exceeding 2000 gallons of rain each year, Portland drainage is something important to all of us,
M. D. Vaden has experience with drainage and soils from years of country club and university campus work on top of landscaping, since 1988. Golf courses are tops tier for turf and soil care and ideal places to observe drainage improvements on a daily basis for months or years.
Images: click to see - landscaping design and drainage project from August 2003, done from scratch. Shown here 9 years later, November, 2012. The dry creekbed behind the water feature is actually a horizontal cistern to catch runoff from the big driveway.
The small photo is from 2003 and shows the week of installation prior to planting. Solid pipe was diverted around the water feature, which itself merely recycles it's water and has nothing to do with the drainage. There's 1000's of ways to design a dry creekbed with different shapes, layouts and plants.
If this page proved helpful, feel free to return the favor by telling a friend about this or other advice topics
About 1 of 3 people who call us about drain line, do not need French drains as expected. For many the real solution involves soil, lawn or other changes. And drainage work tends to involve residual problems that have been ignored or undiscovered for years. Drainage can range from simple French drains, all the way to dry creek beds or decorative rock areas that offer cosmetic and aesthetic appeal. Sometimes is better to collect and remove the water, and for others it may be better to divert it and slowly release it on the property where the soil can handle the moisture.
Click this Rock image to view another project.
We raised grade, slightly convex with a custom soil blend, replaced lawn, added French drain, and edging, increased useable area.
Tips for Do-it-Yourself ...
Various suggestions below should give you a head start. Or introduce you to a portion of our strategy if you are after an estimate. Here are 3 more useful and related pages. Soil Care and Compaction is very important to be aware of, especially in rainy areas like Portland has, were rain erodes or lubricates soil.
Read: Soil Care
Read: Soil Compaction
Read: Auger and Drainage
The DIY drainage and French drain advice may help you avoid installing drainage that you don't need. Certainly you want to get rid of your problems, but sometimes a French drain is not the solution.
Basically, just like the illustration to the right and down the page a little, a French Drain is more or less just a perforated pipe in a trench. Eventually covered with porous material like pea gravel or landscape stone. The simplicity vanishes when it comes to altering and customizing the design for the site. How can the soil affect the drain line or its lifespan? Where are the trees and shrubs, and what will happen with their roots? Could the rock become a projectile if it's near a lawn? Can a pathway with flagstones be a drainage component too?
The most important part of drainage is not knowing how to install it, but understanding whether or not a French drain is the solution.
Heavy rain can trigger material shortages in a matter of hours. Postponing drainage projects until the rainy season can leave people with plenty of water and no pipe to move it. Don't wait until rain storms to install your drainage project.
And in cities like Portland in Oregon, home owners often do less damage to surrounding soil when wheeling materials in dryer summer conditions than during winter when it's wet.
For professionals like myself, we have various strategies and techniques making work at all 4 seasons feasible. But it's much different for novices.
And using Medford, Oregon, for an example, during winter 2005 - 2006, heavy rain depleted many drain line supplies in that city. Their normal yearly rain average is 19" - half that of Portland. And one big rain event depleted that town's drainage pipe reserves. Don't postpone drainage.
Extra example
Click Liner image to the left to view another project.
Liner was used for an area where a deck will installed later.
Typically, French drains will include pipe near the bottom of a trench, with gravel or sand on top. If sand is used, a fabric cover for the pipe will be essential. The pipe is normally perforated to collect or release water, or solid to transfer water. Drain lines can be built with a combination of perforated drain pipe and solid drain pipe: perforated drainage where we want to gather water and solid where we want to move it from point A to point B.
Image: Digging drainage trench walls at an angle is often the most stable, potentially reducing collapse of the edge. But this is not essential. Straight walls can work too. Angled walls mean a wider top, and that can be impractical. It wil depend on how firm soil is, whether you use fabric, and how much space.
Sections of solid pipe can be preferred where trenches discharge water near tree roots. If perforated pipe is located near trees or big shrubs, roots can grow into the gravel and drain line through the perforations. There is little reason to use perforated pipe where the drain line passes areas where water will not be flowing into it.
Success depends on a variety of solutions and materials. Several of these images are from one back yard drainage project where several techniques were used. Perforated pipe was used to collect water. Pea gravel was used to fill most of the trench, but some areas near the surface were back-filled with sand to spare damage to lawn maintenance equipment like core airification units.
Where sand was added over the drain line or pea gravel, fabric was added to keep sand from washing into the drain line and plugging it.
Image right: Preparing to route non-perforated pipe segment under lawn for discharge line. Discharge trenches that are not perforated need no sand or gravel. In this yard, water was collected elsewhere in low spots using catch basins, open trenches and perforated pipe. The discharge under a raised area of lawn required no open trench. With careful diggging, sod can be replaced.
Sometimes, site conditions, or the homeowner's budget, don't allow for stipping sod, completely improving soil conditions or transferring the water horizontally to another area. In situations like this, boring with an auger may help significantly, providing holes which are basically tiny circular drywells - small or large, depending on the auger bit size.
The same basic concept can be done by digging a big submerged cavity to be filled with gravel - commonly called a drywell. This option depends on whether or not the soil beneath the surface will allow water to naturally drain-away or seep out into the sublayers of soil.
A boring method shown in one image on this page, with the small auger, is sometimes used near trees and has been called "vertical mulching" since holes may be filled with amendments like compost. For trees, the goal is often aeration, but occassionally for drainage or penetration of compacted soil layers.
Knowledge of soil & compaction may save installing a needless drain line. Here is a story for example
Years ago, a friend asked about installing drainage at his home near Beaverton, Oregon. He received advice from 2 professional Portland area drain installers that he should install drainage, saying he had a "high water table". About 300 feet before arriving, I was able to rule-out their advice, and within 5 minutes there, could tell him the real problem ... a mushy lawn with standing puddles after rain from surface soil compaction ... not a high water table. I pointed-out the old Oregon oak trees and ponderosa pines on his mid-size lot. Those would not flourish for 50 to 100 yrs. in a to-the-surface high water table. He was convince, and we corrected soil conditions instead of wasting money on a French drain line of no use. Spent one day for a new lawn, and saved a ton of money. To fix the problem, we removed the old sod, ammended the soil and rototilled it. Then planted grass. Problem solved: no mushy lawn, no standing water, and of course, no high water table.
That was one of many yards where I've seen this. And it was clear that the 2 separate "experts" providing estimates did not have a clue about soil and plants. Can you imagine how much money these folks have drained out of people with no need?
Image right: One method that has proved useful in established lawns, is what I call micro trenching. A sharpened shovel with a straight edge can be used to dig tiny trenches only 2" to 3" deep, and maybe 1" to 2" wide. The miniature trenches are filled with sand, and these trenches can extend to another bigger perforated pipe in a main trench. A fabric will need to be used to keep sand from washing into the drain pipe. That system allows water to drain down and into sand, where it seeps away. In a way, similar to how round plugs of soil are removed from golf greens and the holes filled with sand, enabling water to pass through upper sod, thatch and soil. For drainage, the goal is not aeration as much as it is moving some water in selected areas without digging big trenches
Functional dry creekbeds: another technique for drainage, is putting a drain line, or drain lines underneath a dry creekbed - the entire dry creekbed. You can put several sections of perforated pipe next to each other parallel, and even layered one row of pipe on top of one another. This turns a dry creekbed into a holding cistern to control runoff or allow rain to seep into the property.
Sort of a flat drywell.
A French drain is basically a drain line and ditch filled up to the ground surface with rock or gravel. This kind of drainage system may have perforated pipe under the gravel, or may lack drain pipe or tile and rely on water flowing through a trench of gravel alone. But there is a benefit in using a perforated pipe underneath.
Image right: concave collection - It may not be evident from the 50mm photo's shallow depth of field, but the rock shown covers almost 6 x 20 or 120 square feet. Portland gets 3 feet of rain per year, so this recontoured part of the yard with pond liner beneath the stone has potential to capture 360 cubic feet of water (3 x 120). Each cubic foot has almost 7.5 gallons of water. So 360 x 7.5 = 2700 gallons. That's how much water can be collected and released from part of a property, and making it look decorative like a dry creek bed. Plants were added later. Drainage solutions are not limited to French drains.
If a drain line is completely covered with soil, it is not a French drain. A French drain trench is exposed (visible), enabling surface water to run into the trench. It may be concealed partially, such as when grass is allowed to grow into its surface gravel - rarely clogging it, as long as thick thatch does not accumulate. Then the water flows through the trench and away to an opening or porous release area (maybe even a drywell). Sometimes, the French drain trench may be the temporary storage cistern.
If you never see more than, say, 100 gallons of water flowing to an area during week or month, a comparably sized trench may be the perfect choice for a horizontal cistern that slowly releases water between rainy weather days.
In my book, I consider a sand filled trench to be a French drain too, but fabric should cover the pipe beneath if drain pipe is included..
Several suggestions on this page - below - can extend the life of French drains and drain lines. Each idea will require extra time or extra money. But these ideas and methods are inexpensive for the average residential drainage project.
Some French drains fail due to clogging. So, some of this information is geared for preventing clogging. In fact, if your trench will be deep (1.5 feet to 4 feet, or deeper), you should consider lining the wall of the trench with a fabric to prevent soil from dislodging into the rock fill and clogging the upper trench.
1. Many French drains can fail because the soil on the surface presses inward and seals the top of the trench. If the surrounding soil is clay, even a ¼” thick layer of soil would seal the French drain and prevent it from being functional if the soil erodes or moves on top of the trench. A way to avoid this is to slope the sides of the trench so that the top of the trench is wider than the bottom of the trench. Basically, this provides a “V” shape trench opening. When this is done, pressure on the top of the trench pushes energy down and outward on the sidewalls of the trench. If the trench walls are not sloped – thus vertical – then pressure at the surface can collapse the trench walls and press sidewall soil onto and into the gravel; squeezing the trench narrower. So widen the trench top a little bit, and slope the sidewalls.
2. Consider laying a landscape fabric in the trench before installing the drain line and gravel (or sand). This landscape fabric layer can provide a layer that also hinders trench wall soil from pressing inward into the gravel and drain line. Be sure the fabric is porous. This is not an essential technique. It is beneficial, but if you wanted to "cut-one-corner", this may be the corner to cut.
3. Dig the trench a little deeper, and lay one, two or a few inches of gravel on the bottom underneath the drain pipe. No matter how well a drain line is built – a French drain – it probably will get clogged in the future whether 10 years down the road or 50 years from now. Every rain storm will move some silt into the drain line. If the drain pipe is laid on the bottom of the trench, it will start to get plugged with sediment from the first time it functions. But if a few inches of gravel are laid under the drain tile, this gravel base will be what starts to accumulate the initial sediments. This can extend the life of the French drain by years or decades. The deeper the gravel base under the drain line pipe, the longer the drain line can last. The drain line hardly collects sediment at all as long as there is a porous cavity below in the gravel base.
By the way, a smooth stiff drainline usually traps less sediment that the corrugated (ringed looking) flexible drain pipe. But the difference is minimal. The ribs of the corrugated line really don't hold that much. Also, the flexible pipe frequently has better spaced perforations. But if you don't use the stiff pipe, be sure the trench bottom is very even for the flexible pipe.
4. The finer the gravel used to fill the trench, the better for preventing collapse of the trench walls. If large rock is used to fill a French drain – like 2” to 3” diameter river rock – it’s easier for soil to move inward into the cavities between the rocks from the side walls of the French drain trench. Consider using pea gravel or fine gravel like ¼ - 10 crushed gravel. Sand can be used to fill the trench, but a fabric mesh must be used to keep sand from washing through the tiny drain tile openings and clogging the drain line. In many cases, I found that landscape cloth fabrics had smaller openings than drain line fabric. Be sure the fabric will not allow sand to wash through the fabric pores. It may be worth installing a double layer of fabric if sand will be used. But in general, fine gravel can be a better choice than sand. Usually, only a country club superintendent will need to use sand for a French drain when draining water from the sand bunkers.
I'd like to add that sand can add benefits in small areas. For some drains, I've cut "V" shapes slits a few inches deep in areas of water puddles. These slit trenches run from the trench to the perimeter of the puddle. I fill these slits with sand only. Where the slits meet the main trench; the trench is topped with sand, with fabric well-placed to prevent the sand from washing into the French drain. I do this often in lawns, and let the lawn grass spread into the slits. The sandy slits still allow water to move and grass to grow. These are what I refer to as "micro-drainage" or micro-managing a drain line.
Image: take roots for example - Near Tigard / Lake Oswego, we replaced a so-called French Drain that another landscape contractor installed about 1 year earlier. Where they also installed new sod lawn that covered all the trenches (one more flaw). When we removed the perforated pipe they installed, fine roots had already grown through trench fabric and other fabric wrapping the pipe, and perforation holes. IThat was merely a year after install. The image to the right shows a view inside a section removed. The roots entered skinny and branched out. Given time, roots can engulf the entire inside diameter.
5. Use washed gravel. Don’t get crushed gravel like ¼ minus that has a lot of dirt. Get gravel or rock like pea gravel or ¼ - 10 crushed rock that has been washed of most soil. These may have a little bit of a soil film, but in general, are relatively clean. You don’t need a bunch of dirt washing from trench gravel and filling your drain cavity with sediment. Don’t skimp on gravel cost. Get clean rock.
6. gypsum has a tendency to chemically aggregate soil – that’s good. It can help open up the soil structure and make it more permeable. gypsum is inexpensive. If gypsum is added, it can be sprinkled on top of the finished trench and gravel and allowed to leach down and chemically aggregate the bottom of the trench.
7. If the trench will go by tree and shrub roots, consider inserting segments of solid drain line in those areas (meaning pipe with no holes in it's sides). Tree roots rarely penetrate drain line that is not perforated. If perforated drain tile is near roots, those roots penetrate small openings and grow inside the drain line. The invading root mass can become so large that it becomes compressed looking – shaped with rib impressions from the sides of the drain line pipe. The root mass will block water and render the drainage system ineffective.
8. Root barriers are available. If you need a drain to draw water from near trees and can’t insert a segment of solid pipe, consider placing a layer of root barrier against the trench wall between the tree roots and the drain line. Root barriers can be available from bamboo supply businesses, some nurseries and garden centers. Another source is tree or arborist supply stores.
Adding root barrier may be good if only to keep the roots from expanding and crushing the drain pipe someday. Any, or all these ideas combined can extend the life of your French drain. The right procedures and proper planning will prevent or significantly postpone this kind of clogging.
If you slope the trench walls, pressure from above can be diverted downward and sideways. If trench walls are straight up and down, pressure from people walking or machines can squeeze soil into the trench. The slant helps to prevent soil from pushing into the drain line area.
Image right: drainage can be improved in some areas by using a small auger, or a large auger, to bore holes past compacted layers of surface soil. The holes can be filled with sand for for a porous filling. The only drawback in some yards is a difference in color. But if your lawn is not a pristine A Grade area, this could be a good alternative
