Seoul’s Sky Garden~Reuse of an Urban Overpass

This Post by Sandy James Planner was originally posted in Annals of Walking, Inequality, Infrastructure, Landscape,
 Name That City, Public spaces, Rethinking Transportation, 
Urban Design, Urban Planning, Urbanism,  anD PRICE TAGS

This year I visited two of the great urban reuses of existing transportation infrastructure with local designers and creators~the High Line in New York City which was originally a New York Central Railway 1934 spur and the Seoullo 17, the Sky Garden built upon the 1970 Seoul Station Highway Overpass in South Korea. The High Line is 2.33 kilometers long and 30 feet above the ground, and has become an elevated greenway and popular people place. A recent visit was described in a Price Tag Post.

The Seoul Station Overpass was about to be demolished for safety concerns about structural integrity. It is one kilometer long and 17 meters (55 feet) above the ground, roughly the same height as the Georgia Viaducts. Instead of demolishing this overpass, it was seen as a catalyst for urban regeneration and linkages in an area that was previously disconnected for pedestrians.   In 2015 HRVDV won a competition to design a this 33 million dollar project as an arboretum which has 254 species of trees, rhododendrons, and plants (all labelled and in alphabetic order on the Sky Garden).  There are 24,085 trees planted and 645 large pots placed along the Sky Garden. There are baby trampolines (carefully constructed in conical forms), plant sculptures, a bakery, a library and even a nursery. The project opened in May 2017 and has been praised for its  adaptation of a motordom artifact.

There is great attention to detail in the finishings and the construction,  and the Sky Garden is bathed in blue light in the evenings. It is used by people of all ages for walking and for visiting, and is seen as an “observatory” over the different lanes of vehicular traffic below. One of the desired outcomes was for users to become more aware of the heavily used streets  and the glassed in guard rails  of the Sky Garden invite that conversation. There is also an “observatory” platform on the Sky Garden for a more bird’s eye view. The designers have playfully cut large diameter cores into the centre of the overpass and placed clear plexiglass covers over those holes so that pedestrians can view for themselves the “structural integrity” of the bridge’s inner workings.

View from Seoullo 17 of TrafficOne of several entrances to Seoullo 17 integrated into new plazas at ground level

Like the High Line the Sky Garden has been very popular with local citizens and the travelled width of the walkway is only fifteen feet, the same width as much of High Line in New York City. Adminstrators now say that they wish the pathway widths had been a bit wider, but no one anticipated the overwhelming use and acceptance of the space. Even the wayfinding and local maps  are  now designed with the Sky Garden being the central artery to scores of attractions, shops and services from the many entrances to the elevated walkway.  Seoullo 17 has quickly become a central part of Seoul’s revitalization and you can view more about the project’s background and opening day in this YouTube video.

More on Fog Harvesting

Solex roof/fog harvesting system

I have now completed my first fog harvesting system.  It is approximately 200 sq. ft. of surface and captures about 5 litres of pure clean water on average per day when there is fog at night and in the morning.  Materials cost about $2.00 per sq. ft. for construction.  Right now I am not segregating this water, but rather, adding it to the existing rainwater storage tanks.  Since the water is so clean, I might separate it at some point in the future.

The basic collection material is Solexx, a 3 mm thick twin wall UV protected polyethylene that comes in rolls 49.5 inches wide. The material is generally used instead of twin walled Lexan for a cheaper alternative for greenhouses.

In my case I have also installed a gutter on the lower edge to catch the water and transport it to the storage tanks.  I originally bought the twin wall material to cover my pergola just so that I could protect certain cactus and succulent plants during the rainy winter months from too much rain. I was surprised how much fog was condensed onto the polyethylene and dripping onto the surface below, so I added the gutter.

I have also noted that the roof itself is also a fog catcher, but that water is automatically diverted to the same gutters and water storage tanks as the rainwater from the roof. It would be more difficult to segregate the two water sources and its purity might be more of a problem.

Fog Harvesting

I just stumbled onto Fog Harvesting.
I am thinking of setting up a pilot project to see what the cost and yield are for a simple system. If successful I will expand it using my existing storage tanks.  It is completely passive once set up.
It will be interesting to see what yield I get per sq. yd. of material.

Here is another interesting site on this subject. Please comment with what you know about this subject here.

Enclosing The IBC Totes

Above are two pictures of the construction of the enclosure for the IBC totes.  Both picture are from the open end.  The second picture shows the roof sections from above.  Each section is 40" x 10' long.  They lie next to each other with the tar paper overlapping the edge of each section onto the next section.  In this picture there are 5 sections already installed.  That is approx. 200" x 10' or 

16' x 10'.  The first picture shows the same set up from below. Here you can see the tanks.  I have already mounded the wall along the right side between the tanks and the fence.  

With a few more sections I will be done.  The sections are clamped together so that the wind won't blow it away.

For the construction of the roof section I am using very lightweight strips of wood 10'x 3/4" x 1 1/2"

The ribs and ends of each section are 39 1/2"x 3/4" x 1 1/2". Stretched over the frame is a section of plastic fencing material 10' x 40" and above that is the 40lb. roofing material. You can see the sag in the lower photo, but that will be supported so that the span will only be about 5' between the support on the higher tank and the fence.

Fortunately I don't have to deal with a snow load, but I do have to be concerned with rainwater load and wind.  I am installing the sections so that there is a drop of 1/4" per foot so drain the water to one side.  I am using cheap general purpose alligator clamps to hold the sections together so they don't blow away in the wind.

If I have to remove a tank for servicing I can easily remove the roof sections and gain access.

As I add the sides I will shoot some more photos and post them also.

Another Alternative for Water Storage Tanks

While I was picking up my IBC Totes yesterday I had a chance to speak with the operations manager at this olive oil importer and distributor.  There were 10s of thousands of IBC totes at this location. Many of them were empty, some were full of balsamic vinegar and some were full of olive oil.  I had mistakenly thought that the olive oil was transported to this location in the IBC totes.  In fact, only the balsamic vinegar which they also distribute comes in the Totes.  The oil, as it turns out, comes shipped in cargo containers that are 20 ft. by 8 ft. and about 8 ft. high.  The container is filled with a heavy duty plastic bladder that will hold 6,000 gallons.  When the container arrives they off-load the olive oil into the IBC totes.  Then they remove the bladder from the cargo container and hang it so that the oil drains out.  They have found no way to dispose of these bladders other than the landfill. They are obviously capable of holding water.  They cost about $1,000 new and are not reused.  They are thrown out.  In the case of the IBC Totes the plastic and the metal can all be recycled, but not so with the bladders because it is so difficult to get all the oil out efficiently. I was thinking that the bladder could potentially be installed and then cleaned in situ with some sort of detergent or degreaser.

The bladders cannot be just placed on the ground and filled with water. I think they must be contained in something -- either a steel cargo container with supplemental bracing from side to side or possibly with just a hole in the ground.

The distributor is going to give me one to experiment with. I think I can get one when it is folded up into a pickup truck.  I don't really want to dig a hole in my yard that is 20 x 8 and 8 feet deep, even if the bladder is free. And I certainly don't want to put a steel shipping container in the yard (I understand these can be had for under $1,000.)  While this would be a bit cheaper than the IBC totes that I have been using, they would be far less flexible and yard friendly.

If anyone has any bright ideas about these bladders please chime in and let's talk about the possibilities.

Installing the Secondary IBC Tote Storage Tanks

The storm this last week dumped just over 9 inches of rain here.  Unfortunately, my primary storage tanks are already full and I could not capture any new water.  This situation will not be lasting much longer.

I have now purchased 20 additional IBC totes (265 gallons ea. x 20 = 5,300 gallons) and the necessary PVC piping to hook it into the remaining downspouts, the irrigation system, and electric cable for the pump. This will bring my total capacity to 6,400 gallons.  The tanks I got this time cost $40 each and the truck rental to get them here added another $5 to the cost of each. (Total cost for these 20 tanks is $900 including transportation.)

The images immediately below are various views of the in process installation.  The most labor intensive part was leveling out three levels of terraces area to hold the tanks and building retaining walls.  As you can see, the lowest level tanks are now in place, there is one tank each at the second and third levels.  I have also used one tank as a short term holding tank for rainwater as it comes off the roof before it is pumped into the tanks.  I had to do this in order to get the water into those tanks since the gravity feed brought the water in too low to fill just by gravity.  I will use the same holding tank to pump the water into the irrigation system when necessary.

This is the holding tank (not hooked up yet)

I have not purchased the enclosure material to cover the tanks nor the pump yet, but will do so very shortly.  I have already trenched out the ditch for the various pipes and electric line to bring the downspout water to the new tank location. I will set the IBC totes in place and lay the drain line within the week.  Unfortunately, the water from the major storm coming this week will not get into my tanks.  This one storm would most likely fill them to the brim.  C'est la vie. It will have to be the next storm that fills them.  I suspect that when all is done I will have spent another $800 for these other materials.  So, total cost will be about $1,700 for the 5,300 gallons.  That's around 32 cents per gallon installed.

For the primary storage tanks I have found it useful to have a valve to redirect the water from the original drain to the IBC totes.  This is useful when the tanks are completely full.  The overflow for those tanks can't really handle multiple storms.  It just wasn't built for that.  Given the success I have had with this method, I think I will do the same with the secondary storage. (By way of explanation the primary and secondary storage systems are on opposite sides of the house and pick up the water from different downspouts, so I do need two such valves, unfortunately, since they are somewhat expensive).

I found it difficult to find out where the existing underground drainpipe is under the yard.
I have found it useful to have an electrical snake to insert in the drain at the point where the downspout goes into the ground in order to determine how far it is to the first elbow or tee in the drain.  That way, once I know the direction the drain is going I can determine where the pipe is underground at the change in direction.  This doesn't answer every question, but was useful in cutting down on the number of test holes I had to dig.

Since I am going to be stacking the totes (2 high) and the location is not that far below ground level I am going to have to pump the water up into the tanks when it rains.  I will use a sump pump with an automatic on/off switch that is activated by the water level.  I am going to use this same pump to pump water into the irrigation system in order to get the pressure that I need to run through that system.  I will have to have a few valves to open and shut in order to accomplish this.  Haven't worked it all out completely yet, I will post a sketch of how it finally ends up in case you are interested.

I have not been too happy with my filtration system on the primary storage tanks.  I have had to clean it out from getting clogged up three times already.  The very fine grit is coming off my roof and really does a number on the filters.  I have probably removed 20 lbs. of this stuff already since the rainy season started in September.  I think I will just have to clean it out after each rain (2-3 inches of rain).  It only takes a few minutes so it isn't the end of the world, given how much water I am harvesting.

One further note, when I put in the trench to divert the rain water to the secondary set of totes, I inadvertently went slightly uphill in one section.  This was just enough to prevent the water from flowing by gravity to the new tanks.  Consequently, I have dug the trench a little deeper in that section to avoid this problem.  I should have known that water will not run uphill, unless it is a siphon or under pressure.

Protecting the IBC Totes from Light

I am actively working on the secondary water storage system.  I am going to be adding 20 tanks in two rows of 10 tanks, with 10 on top of the 10 on the ground level.  I have already cleared and leveled the area that I want to place the tanks. It is located next to a fence (6 feet high). The tanks will be almost 8 feet in height, so I am going to raise the fence another two feet to act as the light barrier on that side.  I will still have to protect the tanks from light on all the other sides.

On the primary tanks I used hardy board and steel stakes hammered into the ground to construct the shell.  I think that for this bank of tanks I will try to use a more simple and cost effective material.

Let us review the situation.  We have to protect the tanks from UV light infusion or else we will have algae buildup in the tanks and deterioration of the polyethylene tanks themselves.  Next, the material that we use for this purpose must be able to withstand the damage that UV light can produce.

One of my neighbors, who is also installing rainwater  IBC totes, found these covers:

The website for buying them is here. They sell for about $60 each, depending upon exactly how many you buy.  I personally think that is expensive and I am concerned about their durability.  The website says that they are made of a PVC material.  My understanding is that while the PVC may be good for protecting the inside from UV light, the material itself is not durable for UV applications (i.e., the material will deteriorate if exposed to UV light and will have a short lifespan).  I have not verified this last suspicion.  That having been said, I thought I would include it here for those of you who have any sewing skills.  I am researching materials that could be used and will post anything I find that is interesting. Note, if sewing fabric to assemble a Tote caddy, please use the special UV thread that is available (used for outdoor cushions) or you may have durable material coming apart at the seams as the UV deteriorates the thread more rapidly than the fabric.

I have found a high impact polystyrene (black) that would make a wonderful outer shell, but I still have to figure out how to seam it since you could not use a sewing machine for this.

I did find this YouTube video that describes using black plastic sheeting. I again stress that the material used must be able to withstand deterioration from UV light.  I don't think the material used in this video is that type of material.