I’ve expended lots of ink in recent issues extolling the virtues of good water management, but that’s nothing new: Through the years, in fact, I’ve written copiously about the need for conservation and sensible stewardship of the most precious of our natural resources. And this all makes sense, given both the needs of our society and the fact that we who read and write for WaterShapes all derive some portion of our livings from the work we do with water.
On those levels and more, water may be seen as our enduring friend. I must add, however, that water also has a distinctly dark side and can turn on us when we least expect it, becoming unwieldy, unruly and occasionally devastating. This is why in speaking with clients I always make the point that water must be watched carefully because it can turn the tables on us in the twinkling of an eye.
With that in mind, I thought it was about time to balance the scales of my column a bit and consider water’s flaws, warts and downsides while offering some suggestions about what can be done to address these issues in the field.
You don’t have to think too hard to come up with instances in which the presence of water is a bad thing.
Take a situation in which so much rain falls so quickly that drainage swales and storm sewers can’t handle the resulting flow. Especially in areas that are usually dry or have experienced wildfires that have denuded the land of vegetation, too much water in the form of rain can be disastrous: Landslides, overflowing streams, raging rivers and collapsing homes are the sometimes deadly consequences of too much of what is ordinarily a good thing.
Those possibilities alone are enough to make me wary of building watershapes in flood plains or on improperly cut, inadequately engineered grades, and that’s as true on a small scale as it is on a mass scale. Indeed, even relatively small projects are subject to the forces that rise with improper water management, and the results will range from flooded basements or collapsed retaining walls to “popped” concrete pools.
In this context, our ability to control water and bathe its dark side in bright light is paramount to our projects’ long-term viability and client satisfaction.
I’m aided in writing this column by the fact that I’ve worked to counteract water problems for most of my adult life. While employed by a large landscape firm early in my career, in fact, I spent two years doing almost nothing beyond resolving water problems our company’s work had caused on project sites. Most of the time, the issues amounted to little more than figuring out what to do with water standing where it was not welcome – common problems, seldom a big deal, but always something that had to be dealt with effectively and permanently.
What I observed through the bulk of these incidents was that they mostly stemmed either from improper grading – that is, there wasn’t enough pitch to allow the water to drain away – or from construction or insertion of obstacles to drainage without making any allowance for the removal of the water they effectively trapped.
Although in most of these cases there was never any worry about catastrophic failures, I soon learned that no client wants a pond where none was intended. Just as quickly, I figured out that annoyance will turn to anger if the water stands on clay soils and lasts long enough to breed mosquitoes or start to stink!
As I’ve always preached to my own employees, “We’re only as good as our worst details” – so even if a project is worthy of publication and awards, that puddle sitting just out of view in those amazing photographs is the feature on which your client will focus as long as it’s there.
On a more worrisome note, the retaining wall that has been set up without a proper drainage system behind its base may not collapse right away (although I’ve written here about one that started to tumble almost immediately), so you can rest uneasy knowing that, someday, hydrostatic pressure or frost heave will do its work and the water you failed to remove will be the obvious (and legally entangling) culprit.
Truth be told, in almost all such cases the solutions are simple. In virtually every case, in fact, the use of a French drain will solve the problem. This is why I’ve installed these drains as my fail-safe solution for drainage issues for the past three decades: They’re easy to install, require use of no large equipment (depending, of course, on the site) and can carry significant amounts of water.
For clarity’s sake, here’s my definition of this feature: A French drain is a trench lined with geotextile into which a perforated pipe has been inserted at the bottom. This pipe is pitched in such a way that the captured water will exit the trench, which, once the pipe is placed, is then filled with crushed (or washed) stone before being covered with more geotextile. This fabric cover may then be topped by soil, mulch or more stone, and if you’re creative, it can be designed to appear as a dry creek bed or landscape feature.
These French drains come in all sizes and incarnations, but in most residential projects they will include trenches that are nominally 18 inches deep and wide with a minimum one-percent pitch. (A greater pitch is preferable, but even if some water ends up sitting in the pipe, that’s far better than having it sit on the surface!)
Once the trench is cleared, we unfurl a six-foot-wide roll of heavy-duty landscape fabric along the length of the trench, fitting it to the bottom with the fabric climbing both sides and holding the excess in place on both sides to keep it from falling into the trench. We then position a four-inch-diameter, pre-sleeved perforated pipe (that is, a perforated pipe with a fabric sock already on it) in the bottom of the trench, fill the trench to within about two inches of the top (usually with a #2 stone) and fold the fabric over the stone to create a drainage envelope.
With larger-scale challenges, we’ll double the size of the trench and use multiple pipes. We’ve even set up multiple trenches, placing them in parallel a set distance apart from each other to layer the approach. In all cases, our goal is to displace the surface water, move it below grade and keep it both out of sight and harm’s way. On whatever scale, French drains do a fantastic job of removing water, even in situations where the ground would otherwise be consistently saturated and squishy.
In recent years, a number of manufacturers have come up with novel solutions that make the insertion of remedial drainage systems easier than ever before.
One I particularly like (and often use) is the Multi-Flow System offered by Varicore (Prinsburg, Minn.). Whereas the traditional perforated pipe used in French drains has a four-inch diameter, Multi-Flow is a stack of one-inch pipes welded together. One product, for example, includes five one-inch pipes stacked and wrapped in fabric: The entire unit carries lots of water, but it’s only six inches tall and a just a hair more than an inch wide.
The great advantage here is that, instead of having to create a wide, deep trench that typically involves bringing in an excavator or backhoe, these stacked pipes can be installed using a simple four-inch trencher in a furrow the manufacturer recommends backfilling with coarse sand.
Especially for retrofits but also in new construction, the use of this system can result in major cost savings in labor as well as site restoration – particularly where access is an issue. In addition, the supplier makes fittings that tie the product into four-inch piping systems in the event you’re working with existing pipe or need to tie into laterals coming off downspouts.
Earlier, I mentioned a column I wrote years ago about the quick failure of a new retaining wall. While there were many issues with that wall (including poor base preparation and insufficient tiebacks), the immediacy of the failure was the result of improper drainage behind the wall compounded by the fact that additional water was being introduced behind the wall via pipes tied to the home’s downspouts.
This project would inevitably have failed as a result of the first two flaws just mentioned, but I have little doubt that the segmental wall system would have lasted a good while longer than it did had it been equipped with a well-designed and properly installed French drain.
In fact, if you look at the schematics supplied by virtually all of the manufacturers of these wall systems, they all specify installation of a perforated pipe at the bottom of the back of the wall along with landscape fabric and a backfill made up of crushed stone – in other words, a French drain. And this is true whether the walls are to be five or fifty feet tall.
And what’s true with retaining walls is just as true with home foundations or the footings or foundations of structures we build in the landscape. The key in all cases is to give water a path of least resistance – and get it out of there before it can do any damage!
While this column started out as a discussion of just how problematic water can be, it has mostly turned out to be about solutions, with French drains earning the lion’s share of the attention.
There’s a reason for that spotlight: We’ve successfully used French drains to completely dry out properties, to keep water from ever getting anywhere near the top of a retaining wall and, in a number of cases (including my own backyard), to keep a pool’s liner from floating when confronted by high groundwater.
We indeed have a fairly high water table on our lot. For the first several years we were there, the ground would thaw, the spring rains would come and I’d pull off the pool’s winter cover only to find a floating liner. This didn’t particularly bother me, but it was a hassle pumping out the water and resetting the liner.
After a few years I’d had enough of this and decided to install a French drain around the perimeter of the pool, running it to a drainage crock that pumped the water to a culvert in front of our home. The liner never floated again.
As I mentioned, a problem like a floating liner is never a cause for panic, whether my company caused it or not. For me, being called to a site to review and solve water problems is all in a day’s work and gives me a great deal of satisfaction. And just between you and me, it’s nice once the problem is solved to be hailed as a hero by our clients, even if the solution usually involves nothing more than inserting a French drain where it probably should have been in the first place.
Bruce Zaretsky is president of Zaretsky and Associates, a landscape design/construction/consultation company in Rochester, N.Y. Nationally recognized for creative and inspiring residential landscapes, he also works with healthcare facilities, nursing homes and local municipalities in conceiving and installing healing and meditation gardens. You can reach him at [email protected].