1. 9-1 Project 1

3. Purpose To determine which type of material (interlocking brick, wood, nothing, or aluminum cans) when arranged as a retaining wall will hold up best against rain.

4. Hypothesis I predict that the brick retaining wall will protect the soil bed the best. The second best retaining wall will be the wooden wall, followed by the aluminum can wall. Having no wall, will be the worst for protection. I believe this because the brick provides more strength, stability, and drainage than any other wall.

5. Materials Soil Aluminum Cans Rocks Wood Nails Nail Gun Bricks Water Pressure Washer Measuring Tape Tarpaulin Shovel Timer Glue Sticks Glue Gun Saw Safety Glasses Wheel barrow

6. Procedure 1. Collect the materials needed for the project. 2. Build the retaining walls:  Part A: Building the pop can retaining wall:  Glue the cans lengthwise together into rows of 8 and 9.  When the separate rows of cans are made, turn the cans on their sides.  Glue the joins of one row of 9 and place a row of 8 cans on top of the glued joins, followed by another row of 9, etc.  When attaching the rows, they should be staggered for added support.  Step each layer of cans in about a centimetre to form a slanted wall.  Repeat this until the layers are stacked 6 high.

7. Procedure (cont’d)  Part B: Building the Wooden Retaining Wall:  Using lengths of wood that are 2cm x 6cm, mark 6 - 60cm lengths, 2 – 38cm lengths and 10 – 20cm lengths.  Use a saw to cut the pieces of wood at the markings.  Lay the two 38cm lengths of wood parallel to each other on a table.  Lay the 6 – 60cm lengths of wood across the two boards to form a wall.  Use a nail gun to carefully nail each board to the wood that is parallel underneath it.  When finished, for added support, add two angled walls on either end so it can stand up by nailing 5 pieces at right angles to each side of the wall.  Use a saw to cut the wood from the sides on an angle so that the wall sits on the ground.

8. Procedure (cont’d)  Part C: Forming your Brick Wall:  Place three whole bricks in a line.  Begin to stack the bricks, stepping each row in about a centimetre.  The second row starts with half of a brick, followed by 2 full bricks, and half a brick. The joints should be staggered.  The third row should look like the first, and the fourth should look like the second, etc.  Continue this until you have achieved your desired height of 6 rows.

9. Procedure (cont’d) 3. Assemble the Project:  Attach half a tarpaulin against the side of a building and other half perpendicular to it on the ground. This will protect the building and ground from damage.  Place a layer of medium-sized rocks close to the edge of the building. This will help with the drainage.  Lay the retaining walls in place, next to each other, about 30 cm from the building.  Shovel soil in the empty space between the retaining wall and the building.  Place a layer of bricks on each side of the ends to ensure the soil stays in place.  Use your foot to pack the soil down.

10. Procedure (cont’d) 4. Begin the Test:  Spray the first retaining wall for one minute. The spray should cover the top of the soil completely by moving in a repeated left to right pattern.  Repeat this procedure on the second, third, and fourth retaining wall. Repeat this cycle 10 times, so that you have actually sprayed for 40 minutes in total. 5. Allow the soil to dry and repair all damage. 6. Repeat numbers 4 and 5 for two more trials.

13. Variables Manipulated Variable: The manipulated variable is the type of wall used. Responding Variable: The responding variable is what happened to the soil bed. Controlled Variables: Amount of water sprayed on soil bed Amount of time water was sprayed on soil bed Amount of soil behind the walls & how well it was packed Size of the walls Pattern in which the water was sprayed on the soil Use of no wall.

14. Results Table 1: Changes Observed in Soil Bed during Testing Time (min.) 012345 Brick Wall Wall and soil bed are not damaged -no change to wall -water flows downward No change -water just drains downward -no change No change No Wall Soil bed is not damaged Dirt, water, and mud wash down the wall in landslide form The flow of dirt and water is not as big this time The mud, water, and dirt comes down in a landslide and piles at bottom of wall A river forms along the wall washing the dirt out along with the mud and water Pop Can Wall Wall and soil bed are not damaged Dirt gets wet and falls behind wall A landslide forms when dirt falls behind wall An empty space forms between where the top of the soil bed was and where the wall is Water and soil drains down the hole and through the sides of the wall No change Wooden Wall Wall and soil bed are not damaged Big pools of water form on top of soil bed On the sides of the wall the dirt and water wash and drain away Water and soil drain down the side

15. Results Table 1 (cont’d): Changes Observed in Soil Bed during Testing Time (min.) 678910 Brick WallWater sinks downward No ChangeDrainage on back of soil as well as downward No Change No WallLots of soil and water move like a landslide On sides, soil and water wash out Soil comes out further in landslide form Continues to wash out Pop Can WallDrainage on sides of wall. Water seeps down behind wall No Change Soil moves. Water drains down behind wall, an around cans Continues to wash away Wooden WallLots of soil and water draining causing a big hole where it drains down the sides Water and soil block the draining space causing a flood Most soil on top washes down with draining water. Other soil stays since it has settled Washes out along sides of wall. Water and soil get washed out Lots of washing out on sides of wall

16. Results Table 2: Changes Observed in Soil Bed during Testing Time (min.) 012345 Brick Wall Wall and soil bed are not damaged Water flows downward A small pool of water forms on top Water sinks downward through soil Water just drains downward through soil No change No Wall Soil bed is not damaged Water and soil wash out on the front of wall No change except for the soil takes a landslide form No changeWater and soil still move down front of the wall A river flows at the bottom of the wall making a path for the soil and water Pop Can Wall Wall and soil bed are not damaged The soil moves in the soil bed A path is formed where the water moves down the sides and out the bottom of the wall Dirt causes a landslide behind the wall An empty space forms where soil left in the landslide More soil moves behind wall Wooden Wall Wall and soil bed are not damaged Water drains downward No changeA path is starting to form on the side of wall for water Soil starts to move along the water’s path A lot of soil and water move out the side of the wall causing a hole on the top of the soil bed

17. Results Table 2 (cont’d): Changes Observed in Soil Bed during Testing Time (min.) 678910 Brick WallWater moves downward Some dirt sinks through leaving a few rocks on top No ChangeDrainage on the back of the wall causes a little soil to flow out Soil is settled and water moves downward No WallAnother landslide forms On the top of the wall, big chunks of soil are missing from the landslide The soil washes mostly down the sides of the wall The soil bed washes out Continues to wash out Pop Can WallSoil and water continue to wash away No ChangeThe wall moves out slightly Soil and water keep washing away The gap between the wall and what was the top is the soil bed is very large Wooden WallMore water flows out this time without as much soil The soil seems settled as less water seeps out the hole Even less water seeps out of hole Soil starts to wash out again No change

18. Results Table 3: Changes Observed in Soil Bed during Testing Time (min.) 012345 Brick Wall Wall and soil bed are not damaged Water sinks down through soil No changeWater stays above soil slightly longer before sinking No changeWater just sinks down through soil bed. Nothing affects this wall No Wall Soil bed is not damaged There is an initial landslide Leftover soil comes down over the wall The soil flow over the wall is not as heavy The soil flow almost completely stops and looks like it has settled Another landslide moves downward Pop Can Wall Wall and soil bed are not damaged The soil moves in a landslide behind the wall More soil moves in the landslide Water just drains behind the wall and out the bottom On the sides of the wall little amounts of water flow out but mostly under the wall No change Wooden Wall Wall and soil bed are not damaged Water pools in large amounts on top of the soil bed No changeA large flow of soil and water moves through a side in the wall A landslide occurs No change

19. Results Table 3 (cont’d): Changes Observed in Soil Bed during Testing Time (min.) 678910 Brick WallWater sinks through back of soil bed and down through Drainage on back of soil bed increases No changeDrainage on back lessens and moves mostly down through soil No Change No WallAnother landslide moves down wall No changeMostly water moves down wall Soil seems like it has settled A mound of soil forms at the bottom of the wall Pop Can WallMore water moves behind the wall Some soil moves along with the soil this time A small landslide occurs Mostly water trickles down behind the wall No change Wooden WallA lot of water and soil move out the stream that has been created No changeA lot of soil has disappeared from what was the top of the soil bed Another landslide occurs but mostly water this time More water than soil moves down the stream causing flooding

20. Results

22. Analysis In order to create a numerical value to translate into a graph, the effectiveness of each wall in maintaining the soil bed was given a rating from 1 – 10, as shown below: 1 - complete destruction of soil bed. 3 - major damage including landslides. 5 – moderate damage with little evidence of landslides. 8 – minimal damage with no landslides. 10 – no change in soil bed.

23. Analysis Effectiveness of Retaining Walls Type of Wall Effectiveness of walls on 1-10 scale

24. Conclusion I determined that the brick retaining wall provided the best protection of the soil bed against the simulated rain. Not only did the bricks provide strength, but stability and drainage were evident throughout the tests since the water filtered through the soil bed instead of creating pools of water on the surface. There was no evidence of collapse or formation of rivers. Next was the pop can wall. While there was some settling, it did provide quite a bit of protection. Some of the settling may have been due to insufficient packing of the soil bed. It was difficult to pack because the joins between cans were so fragile that they would break with too much strain. This makes the environmentally friendly option a poor choice for real life applications. However, the small gaps between cans helped with the drainage making it a reasonably good retaining wall.

25. Conclusion (cont’d) The wooden wall performed slightly better than the control of no wall, which eventually washed out. Above the wooden wall, large pools of water formed on the surface of the soil bed creating a river which washed down the side creating a mini-landslide. This shows the importance of drainage in a retaining wall. Perhaps this wall would have worked better if small drainage holes had been drilled. In conclusion, when deciding on an appropriate material for a retaining wall, the choice of material will depend not only on strength, but also stability and ability to drain. Interlocking brick is an excellent choice. It functions well and looks good.

26. Sources of Error There were some inconsistencies in how well the soil was packed behind the retaining walls. It was difficult to pack the soil down properly without destroying the pop can wall. Some repairs were necessary as the project was being set up. Because pop cans and bricks are a fixed size, the walls may not be exactly the same size. Two different loads of soil were used. One had more rocks and sand than the other. I tried to ensure that equal amounts of both types were used in the soil beds. However, one may have had more rocks which would cause extra drainage. The angles of the retaining walls were slightly different because of the materials used. This may have affected the amount of soil used behind each wall.

27. Ways to Improve Make the retaining walls enclosed on three instead of one side. This may eliminate some of the problems with soil washing away. Try a larger scale. Test using different levels of pressure in the water. Test the strength of the wall by spraying water directly at the wall (such as occurs with ocean waves). Include more types of walls such as packed rock or glass block. Set up the walls and leave them exposed to the earth’s elements for a period of time to see how they respond to the sun, freezing temperatures, snow, rain, etc.

28. THE END!