The benches at Laurel Tree Learning Center

Abstract[edit | edit source]

Three Scoops Three Flavors is a set of three benches built for the primary students of Laurel Tree Charter School. The bench set is built to provide an outdoor space for class meetings, performances, gatherings, and is also designed to be used as an interactive playground structure. Additionally, the bench is a model of sustainability built to teach and raise awareness within the student body of Laurel Tree.

Background[edit | edit source]

Team Primary Benchspiration is a part of Cal Poly Humboldt's Fall 2012 Engr215 Introduction to Design Class. The team is composed of Jerrina Alverio, Andy Eggink, Caleb Fowler, and Allison Molleson. Team Primary Benchspiration worked in partnership with Laurel Tree Charter School to design and build a semi-circular bench for the latter's primary students. Laurel Tree Charter School is a K-12 school of approximately 110 students located in Arcata, California. The bench was built as a function of the mission of Laurel Tree to create a sustainable model of education.

Problem Statement and Criteria[edit | edit source]

Team Primary Benchspiration's objective was to design and build a bench for the primary students of Laurel Tree. Prior to the project, Laurel Tree did not have outside seating for class meetings, performances, or gatherings. Laurel Tree wanted youngest students to have a place to play and call their own during recess. Additionally, the design elements of the project include features of the bench that are "playable," such as checkerboards, a pipe-o-phone, a rock climbing wall, and a xylophone, to expand the outdoor activities available to the students. The following criteria were formed in collaboration with Laurel Tree.

  • Durable and Functional
  • Use of Sustainable or Recycled Materials
  • Aesthetically Pleasing
  • Interactive for Primary Students
  • Signage Relating to Sustainable Implements and Truth Window
  • Safety
  • Half Round Shape
  • Low Embedded Energy
  • Seats at least 20 Primary Students
  • Cost

Project Solution[edit | edit source]

Solution Description[edit | edit source]

Three Scoops, Three Flavors is a bench design created and constructed by team Primary Benchspiration. The bench was designed specifically for the primary school students at Laurel Tree Charter School. It was meant to be not just a bench, but also a play area for the students. The design is in the shape of a semicircle, in the style of an amphitheater and consists of three different bench types, each bench having playable features.

The Urbanite Bench[edit | edit source]

The Urbanite bench is the largest of the three benches at around three and a half feet high (four feet high is considered the maximum safe falling distance for primary student playground equipment) citation, and is the center bench in the semicircle. This bench is made from urbanite(recycled, broken concrete). The urbanite is covered in a layer of cement averaging 2” thick to provide stabilization, safety, and comfort. There is also chicken wire in the cement, which allows for greater tensile strength and impact resistance. This bench has three separate tiers, while the other two benches have only two. This provides extra seating, the required height for a climbing wall on the back of the bench sized for younger students(while falling below the recommended "safe playground equipment height" ref for younger students, no pun intended), and a more pleasing overall aesthetic. On the back of this bench are two different playable options, and a small mural. Rock climbing holds protrude from the back of the bench to create a small rock wall for the students to climb on. On one side of the rock wall is a mural depicting the laurel tree logo of Laurel Tree Charter School. Each leaf of the tree is a leaf shaped tile, previously made by the children as a school project, with one of the focus words of the school written on each leaf. (Has not been done) On the other side of the rock wall is a series of eight 2" wide aluminum pipes of differing lengths tuned to a diatonic scale. In a diatonic scale you can never hit an off-key note, allowing the children the freedom to experiment boldly with melodies, while developing ear training. Cutting pipes to the proper length for a pitch is difficult, since there are so many materials and gauges of pipe available, and securing them at the proper nodes to allow for free vibration can also be a complicated matter. Fortunately, we found a website with detailed information on just about anything you would ever want to know about making chimes, including even specific measurement tables spanning many possible octaves for different materials and gauges of pipes, with length and node measurements for each semitone. The website is found here: An Engineering Approach to Wind Chime Design and Build.

The Ecoladrillo Bench[edit | edit source]

The ecoladrillo bench is made primarily from stacked, recycled, plastic bottles. It is reinforced with rebar, chicken wire, and recycled steel grating. This bench is also covered in cement averaging 2” thick to provide stabilization, safety, and comfort. This bench has only two tiers, the backrest of this bench being shorter than the center bench and not extending the full length of the bench. This allows for extra seating and a more pleasing aesthetic. Painted on the top of the seat back are checkerboards, tic-tac-toe bards, and mancala boards.

The Earthbag Bench[edit | edit source]

The earthbag bench is made from earthbags. Earthbags are simply sandbags filled with dirt. In this case, for increased sustainability, all of the dirt in the earthbags came from the dirt dug up for the foundation. The bench appears to be identical to the Ecoladrillo bench except that the interior is made from earthbags, and it has(will have) different gameboards on top of the backrest.

Costs[edit | edit source]

Item Source Quantity Team Cost ($) Total Cost ($)
Funnels Harbor Freight 2 3.22 3.22
Tarp Harbor Freight 1 12.95 12.95
PVC pipe The Mill Yard 20' 17.50 17.50
River sand (yards) Eureka Ready Mix 1.5 63.00 63.00
Cement Ace 4 48.00 48.00
Earth pigment ABC (20% Discount) 5 60.00 72.00
Root barrier fabric Ace 60' 78.00 78.00
Sandbags United Rentals 100 81.00 81.00
River sand Wes Green 3 128.70 128.70
Yard of road base Eureka Ready Mix 3 Donated 128.70
Wood Miller Farms Donated 200.00
Urbanite Miller Farms Donated 200.00
Tiles The Tile Center 60 Donated 35.00
Stakes Miller Farms 12 Donated 20.00
Rebar The Boiler Works 80' Donated 20.00
Plexiglas Longstroms Donated 60.00
Plastic bottles Eureka Recycling Donated 50.00
Lime powder Jungle Mike 5 Donated 40.00
Chicken wire The Farm Store 100' Donated 50.00
Cement Lungstroms/Piersons/Hensel 10 Donated 120.00
Barbed wire Miller Farms 200' Donated 20.00
Aluminum pipe Arcata Scrap 24' Donated 27.00
Aluminum molding Arcata Scrap 25' Donated 5.00
Climbing holds Far North Climbing 13 Donated 80.00
Misc. Hardware On hand 30.00
Totals $492.37 $1,590.07

Total Labor Hours (insert)

How to Build[edit | edit source]

This project can be implemented in a variety of shapes or sizes to effect a desired solution. Our design was built in a semi-circular configuration consisting of three separate bench sections designed to fit the needs and layout of Laurel Tree Charter School.

Step one: Making measurements for the foundation. Find the approximate center point of the semicircle you wish to build on, and mark it with something you can trust to not get moved around during the building process. A sizable rock driven flush into the ground with a sledgehammer is a good option. This point will become the basis for all of your measurements, so first have someone stand at possible center points holding a measuring tape while another person takes the end of the measuring tape and tests out the feel of different outer circumferences for the benches, walking around the perimeter back and forth to make sure that proposed arcs are not obstructed by other feature on the site.

Fig. 1 Gravel Foundation
Build a foundation appropriate for your location. Our foundation was installed using "roadbase" gravel which packs very tightly to provide a strong platform on which to build. We dug our foundation in the shape of our bench 4"-6" deep and to extend 6" beyond the dimensions of the bench. Then we installed weed block fabric and finally filled the excavation with roadbase. Retain dirt from excavation for earthbag bench.

Start Urbanite bench

Fig. 2 Urbanite Bench
Build your bench in the appropriate size and shape using broken concrete, also known as urbanite. Build up the structure in layers and use sand to fill in between the urbanite pieces and in between the layers. Sand can be used to level the urbanite and to make up for varying thicknesses of the broken concrete.
Fig. 3 Urbanite Bench with Form
Build a concrete form around your finished urbanite bench. The form should be 2" from the urbanite to allow for a 2" layer of concrete to be poured. Additionally, the form should extend above the urbanite to the appropriate seat height. This will also be filled with concrete and leveled. The edges of the concrete should be rounded prior to it becoming too stiff to form.
Fig. 4 Final Urbanite Bench
Remove the forms and save for the other benches. Alter the forms as needed if the other benches are different dimensions.

Start Earthbag Bench

Fig. 5 Earthbag Bench
Using the dimensions of your bench, calculate the approximate number of earthbags that you will need. Fill the earthbags with the dirt from the foundation excavation. We built a simple earthbag filler to make this process easier. Fill the appropriate number of earthbags. Using the earthbags build the appropriate size and shape of your bench, laying two lines of barbed wire down on each row of sandbags, between each layer of sandbags.
Fig. 6 Forms on the earthbag bench
Using the reserved concrete form from the urbanite bench repeat steps 3 and 4 using the appropriate sized concrete forms.

Start Ecoladrillo Bench

Fig. 9 Ecoladrillo Bench
Build a structure of chicken wire in the size and shape of your bench. Stack plastic bottles with the caps on inside the chicken wire so that they fit tightly to reduce compression. Fit rebar from the ground up in the shape of your bench every 8 inches. Tie this vertical rebar together using rebar placed horizontally at appropriate locations.
Fig. 10 Ecoladrillo Bench with forms on it
Using the reserved concrete form from the urbanite and earthbag bench repeat steps 3 and 4 using the appropriate sized concrete forms.
Fig. 11 Applying Plaster
After the cement on the benches has cured appropriately, apply a skim coat of lime plaster to the surface. The lime plaster seals the concrete and allows a pigment to be used to create an aesthetically pleasing style. At this time apply any other external features of the design. We applied tiles created by the primary students of Laurel Tree before we applied the lime coat.

October 2014 Update[edit | edit source]

The benches, constructed two years prior, now show some weathering. A final coating of lime plastering was sprayed over the bench, including over the tile to protect cement; the spray has since worn off leaving a rougher texture. The climbing wall and xylophone could use minor maintenance and cleaning but function as designed. A Plexiglas piece covering one of the Truth Windows has broken; the school is debating whether or not to replace with a stronger alternative or plastering over them. Signage for information on recycled materials in the benches is missing. Original planned checker board games to be placed on top of the benches have weathered away.

School Input & Project Results[edit | edit source]

This project was undertaken during the fall, which experiences high levels of precipitation. This made construction of an outdoor project difficult and provided poor working conditions for those involved which delayed progress. In future outdoor projects they'll consider seasonal conditions, most likely starting in the drier spring.

Laurel Tree reports that the benches are regularly enjoyed by students and the staff is pleased with the overall results.


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