One That Got Away: Challenging Retaining Wall in DC

One of my favorite things to do on this blog is to profile recent projects. It’s a fun opportunity to show what’s possible, and maybe brag a little. Hey, my clients let me create some great landscape designs for them!

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As I was thinking about a recent sale I didn’t close I realized I should blog about it as well. After all, what killed the deal were the realities of the site and the budgetary challenges they created. There might be something to learn from this, especially if you’re planning a DC landscape design project of your own.

The site: A rowhouse in DC. It’s in a hilly neighborhood off of Rock Creek Parkway and there is a HUGE amount of elevation change between the street and the front porch.

All the homes in this neighborhood have a 10-12 foot tall stone retaining wall right at the city sidewalk. This client’s wall had deteriorated, so last year he had the wall rebuilt. Such a wall requires a huge cantilevered footing, which meant digging way back into the hill. Because the wall was being built right at the city sidewalk all excavated soil was hauled off site. The new wall was built, including a 4 foot wide set of curved steps, and only some of the removed soil was brought back.

The project for which I was called: Prior to the new wall’s construction, the homeowner had an 8-10 foot wide level piece of lawn in front of his porch. Since the wall builders didn’t bring all that soil back, it now plunged off like a ski slope. The homeowner, therefore, wanted one or two natural stone retaining walls built behind the big wall to level off the yard, new landscaping, and new low voltage landscape lighting.

Wowsers. The client wanted to have a sense of the budget, so my masonry contractor and I sat down, had some coffee, and talked it over.

The challenges:

– Access. Parking in DC is a challenge, and with the sheer wall right at the sidewalk there would be nowhere to stage materials. Everything would have to be hand carried up the steps and staged at the top of the lowest wall. If the steps were a straight shot, we could have laid boards as ramps and wheeled materials up – but that wouldn’t work on the curved steps. Getting concrete up to the wall footers would require a pump truck.

– Work area. The only space to stage materials and mix mortar is a small flat pad at the top of the new retaining wall. That means a lot of shuffling things around every day, reducing efficiency.

– Backfilling our new walls. Again, the material that was here originally never came back. This means that we would need to bring in between 40-60 cubic yards of fill dirt and topsoil. To put that in perspective, a full load in a standard tri-axle dump truck is 12-14 cubic yards.

So how would we get this quantity of soil up to the top of the site? As mentioned above, wheelbarrows were out. Hiring a ridiculous number of laborers and doing a bucket brigade would be just… ridiculous. We settled on having Sislers Stone put the soil in super sacks (sturdy bags that can hold a ton of bulk material), truck them to the site with a flatbed, and lift them into place with a rented crane. Logistics!

– Safety. Any time you have a retaining wall on a slope above another retaining wall, there’s a possibility that it will exert forces on the wall below. I let the client know that as part of the landscape design process I would have a structural engineer look at my drawings, and if he felt it required his involvement that would be an additional cost.

After all this, the landscaping and lighting were a small portion of the project cost, but it all added up. In the final analysis, we figured it would cost a minimum of $30,000 to complete the project. It was more than the homeowner wanted to spend, so we’ll hopefully revisit it later.

The unfortunate thing is that this is a $30,000 landscape installation project that could have been avoided, or at least reduced. The company that rebuilt the wall clearly didn’t work off of detailed plans or specifications. I know this because the client told me they built the steps in the wrong place, and there was clearly no communication up front about the soil hauled off site being brought back. This is yet another case where starting with a landscape designer – someone who could create a detailed set of drawings and a complete scope of work – could have saved thousands of dollars.

I would love to save you thousands of dollars! If you’re looking for a landscape designer for a project in northern Virginia, DC, or Maryland, contact us for a consultation!

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