Pearl's Retaining Wall
Opalyn layouts a key part of this spring's work
Hi, my name is Opalyn and I am one of this spring's interns. I spent four years with the USN Seabees and recently completed two Bachelor Degrees. I arrived on a sunny Thursday afternoon after spending several hours in Portland learning how Windward is building relationships that link urban and rural sustainability endeavors. After a very short tour and a movie, I turned in for the night. I awoke the next morning to snow flurries which turned into flakes blanketing my new home. Three walking tours later and there is still more to see around every corner.
Because of my drafting experience in the Navy, my first project is to draft the retaining wall and foundation that will support the Freezer Trailer. I have been using freeware from Google called Sketch-up. As with any new program, getting it to do what you want can be challenging but the on-line tutorials are very helpful and it is much simpler than other drafting software.
The retaining wall consists of six concrete pads supporting the six cinder block piers with seven sections of concrete wall. Click Here to read about the work done last fall on the first of the concrete piers.
as viewed from the southwest
As you can see, the cinder block piers rest on concrete (gray) pads. The black line represents the existing ground level. As this dirt is excavated it will be transported to the back side of the wall to provide earth sheltering for the lower area where the fish tanks will be located.
as viewed from the northeast
In the future you will be able to view more drawings including the freezer trailer, the aquaponics lab, and an area for growing herbs, tomatoes, and strawberries. The building is now called the Pearl.
[Walt: we first built a micro-aquaponics setup inside of Vermadise to learn about the hydraulics involved in combining fish (starting with cold-water tolerant goldfish) and plants (different types of salad greens). That was followed by a mid-sized set up focused on the chemistry involved, and adding duckweed to the mix. Our third aquaponics set up will build on that work and add the challenge of keeping the fish tanks and grow beds warm enough to support the tilapia. As this will be our "flagship" aquaponics system, we've taken to calling it our Pearl.]
Opalyn slips a short length of rail road tie into place
Our soil has a lot of clay in it, and while the spring moisture makes for easy digging, it's not the most stable load bearing surface. So, before getting started on digging the trenches in which we'll pour the retaining wall's foundation, we elected to shift the trailer down hill a couple of feet and to then distribute the weight further by installing railroad tie cribs.
the freezer trailer shifted downhill to facilitate building its foundation wall
There's a notable amount of slope where we're siting this building, so we wanted to make especially sure that the trailer was well supported and level. It took a couple of afternoon work parties to get it up on solid cribs fore and aft, but that's fine with us since safety is much more important to us than speed.
the freezer's front resting on its own crib
With the drafting of the foundation complete, I decided to add the freezer trailer and the first draft of the ten fish tanks. Next, I will add details to the fish tanks or work out the details of the roof and its footing, including the change in elevation between the foundation and the pitched roof/wall.
I am continuing the excavation so that we can pour the pads for the cinder block piers. Before I headed to my family reunion, I built the frame for the corner pad and bent the rebar to support the corner pier. I know that two pieces of 2x6 and two pieces or rebar is nothing to get excited about but for me it was exciting. My experience in the Navy gave me the opportunity to draft projects but I transferred to my next duty station before any of the projects were completed. Being able to see the project go from the drafting board to reality and being part of it really jazzes me up.
After checking and rechecking to make sure that the second pad was level and square with the first, it was time to crank up the mixer again. It may not be obvious but the second pier is the most critical of all the piers since it forms the second of two points that determine the plane of the foundation, and thereby the plane of the entire structure.
Since this was the first concrete pour of the season, a good deal of time was taken up in gathering the requisite extension cords, hoses, tools and such, but in short order the mixer was cranking, and concrete was being loaded into the form. Then comes the key step of setting in place the first two cinder blocks--lots of checking level and alignment to make sure that everything is good to go since accuracy here pays dividends down the line.
With spring finally here Monica and I finished repairs on the outdoor Duck Palace and Guinea hen pen yesterday while Annie spent the day at Mount Hood. She returned to Windward with Orly, our newest intern. Today Monica and Orly helped Walt and Annie move the ducks and guineas out doors while I built the first pier up to a height of 5'-7".
We decided to add one more layer of cinder blocks so the final height will be over six foot but the freezer trailer was in the way. It will have to be lifted several more inches to accommodate the last layer of blocks, but that extra bit of headroom will make it easier to work with the fish.
Over the past week I have been thinking a lot about the dichotomy between Windward and my military experience. When I arrived at Windward, Walt turned the Pearl project over to me and while he is more than happy to answer questions and have discussions to clarify the project, he really means it when he says, "You are lead on this project."
Last week when the pad was ready to be poured, I had expected him to look at the form and take charge of the project while we worked on it together. He did not, instead he asked questions to make sure that I knew the next steps and allowed me to determine if more concrete was needed and to set in the first two cinder blocks. He did not hover or micromanage at all. He offered his help and when I didn't have any more questions, he left me to finish setting the blocks on my own. His attitude is extremely empowering and encourages me to work harder to make sure the work turns out right.
In contrast, while doing survey work in Alaska for the Navy, my work was subject to review and scrutiny, while at the same time my supervisor would not answer my questions about the project and was very sparing with details. This was very frustrating for me.
Pier #2 starts to grow
This pier is one of our corner piers and the challenge was how to cap the rebar openings on the cinder blocks since the rebar only sticks out on one end instead of both ends like on the first pier. The corner form will be strapped to the pier also holding the rebar seal plates in place.
Walt shows me how to use the rebar tie spinner
Two mixes of concrete produced an excess of concrete so instead of letting it go to waste we raised the pier to a total of five cinder blocks.
Killer inspects the form just before concrete starts to pour.
The pit for pier #3 with the orange line showing placement of the form and the need for a bit more excavation
Excavation has been the order of the week. In addition to the water level I set up a few days ago, I also set up the line for the new pad, then dropped two ropes down into the pit showing the location and elevation of the corners of the form.
Form for Pier #3
I spent Tuesday in Portland with the Away Team, and on the way back picked up Jen, our newest Intern, at Portland International. Jen's an Environmental Studies major who's just completed her junior year at Ursinus College in Pennsylvania. She and I arrived back at Windward late, and raided the kitchen for a midnight meal of peacock, pickled eggs, mashed potatoes, and gravy.
Since arriving Jen has been helping everyone with their projects in order to get a feel for what's going on before taking on a project of her own. On Thursday she helped me start work on the next phase of excavation--digging out the area between the piers for the footings for the main body of the retaining wall.
our newest 'tern grabs a shovel and helps dig
Here's a sketch up illustration of where we are on putting together Pearl's retaining wall / foundation.
The work truck returned from a run to town with 50 of the cinder blocks needed to continue building the piers, and the 'terns made short work of unloading the truck before heading off to their various projects.
We also built up piers 2 and 3 past the 4' tall point, and then filled them full of concrete.
Last week, I spent three days in Portland. I attended several events at the Village Building Convergence. I plan to share the things I learned at the Bodyversity workshop when the next intern arrives in a few weeks.
Back at Windward, I focused my energies on excavation and trimming our forest. I was using a pole saw to trim one of our pine trees. When the twisted branch fell, I didn't get clear and managed to bruise my arm. This curtailed digging but provided time to look at the project's next step which includes determining the elevation at various sites and updating the drawings.
Here's a drawing that shows the addition of the treated 2x6 that goes on top of the retaining wall to provide a cushion to distribute the weight of the freezer container.
Yesterday, I set up a water level to determine the change in elevation from the north side of the Pearl to the south stem wall. The bottom of the footing for the north retaining wall is 20" below ground, meaning we will be excavating under the freezer trailer to make room for the fish tanks. The question I need to answer was where the site's natural slope made the surface level with the bottom of the retaining wall's footing.
Downhill, the southern stem wall will provide support for the greenhouse's 45° polycarbonate southern wall/roof.
Updated plans showing the foundation, stem wall, and the freezer unit
As Monica and I continued to excavate the footings for the Pearl's retaining wall/foundation, one section became persistently wetter the deeper we dug. We called for reenforcements, and Emily, our most recently arrived intern pitched in on the excavation for the footings. By then we had standing water where the footings was supposed to go, so we decided to excavate a trench to the faucet about 2 feet away in an effort to find the source of the water.
As Emily and Monica worked their way closer to the source of the leak, the soil became progressively more fluid finally turning into a mud wallow, just the thing for hot, dry feed on a sultry June afternoon.
It took a while, but we back-tracked the water to a malfunctioning freeze-proof faucet. This style of outdoor faucet uses a drain plug which, when you shut off the faucet, allows the water in the exposed pipe to drain back down into the ground thereby preventing freezing. The plug on this faucet had been invaded by oak tree roots which prevented the drain from working properly. Now that we knew what the problem was, we removed the old faucet and made a temporary repair.
Since my last update, we have been working to build three of the northern piers to their final height and excavating for the footings. The northeast pier has reached its final height but not without some challenges.
When the first cinders were placed they sunk into the concrete before it cured causing the pier to climb at an awkward angle. First, we considered using shims to bring the pier back to level, but they made the pier looked more lopsided, and it was no longer in line with the other piers.
Because this solution created more problems than it solved, we decided to dismantle the pier and build a form to pour a new level pad. With the new form in place, it was time to fire up the concrete mixer again. In the pic below, notice the waterline to the right - I'll talk more about this in a minute.
In the next pic, you can see us "milking" the concrete to submerge the rocks and create a smooth surface. Soon it was ready to receive two cinder blocks which we settled into the leveling pad and watched to ensure that they remained level as the concrete continued set.
With a new level surface to work with, Matt and I were able to quickly get the pier ready for more concrete quickly.
Two more mixes of concrete and the pier reached its final height. With one pier complete, its height determines the height of the entire structure.
In order to complete the other two in-progress piers we need to either raise or move the freezer trailer. While we work out the best way and direction to make the move, we will continue excavating the footings.
Remember the waterline I mentioned - we need to move it since we'll be excavating the space under the freezer trailer, a process which would expose the existing water line. One solution is to dig it deeper, so that it passes under the footing and below the excavated space where the fish tanks will go. A second, less attractive, solution would be to reroute the water line around the Pearl but this would mean adding four 90° turns to the line--since this is our main north-south water line, we're reluctant to do anything that would restrict its flow.
At this point, we're looking at just digging it deeper.
Notes From Windward - Index - Vol. 68