Appendices To Manual > G (2) - 330 Lb Concrete Filter Construction Manual

Concrete Filter Construction Manual BioSand Water Filter - Version 8.0 Humanitarian Service Last Revised: June 2005 MAKE PVC STANDPIPE Estimated Time: 10 minutes Tools Needed: • ½” PVC pipe • Three ½” PVC 90˚ elbows •

PVC primer and glue (optional)

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Tape measure 1 file or sandpaper 1 saw / hack saw

1. Measure and mark a 60cm length of PVC pipe. 2. Cut the piece of pipe with a saw. 3. Measure, mark, and cut a 7.5cm piece of pipe. 4. Measure, mark, and cut a 3.5cm piece of pipe.

5. Smooth all cut ends of the pipe with the sandpaper or file. 6. Assemble the three lengths of pipe and the three elbows as shown below. Note: If the PVC components fit together tightly, gluing is not required. However, there is a risk that the pieces could pull apart when in the wet cement.

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IF GLUING IS REQUIRED:

7. Clean the ends of the PVC pipe and the interior surfaces of the elbows. 8. Completely coat with primer all the connections that will be glued together (i.e. the ends of each pipe and the inside of each elbow).

9. One at a time, coat the inside of each elbow and the corresponding pipe end with glue and pushed together firmly. 10. Hold together for a few seconds, and then release. 11. Repeat for each connection until the standpipe is assembled as shown.

PREPARE MOLD Estimated Time: 30 minutes Tools Needed: • •

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1 level Vegetable oil Two ¾” wrenches Brush or rag to apply vegetable oil Wooden shims of various sizes Wire brush, sandpaper, or steel wool to clean mold

1. Clean the steel mold to remove any attached concrete. Leave excess concrete on all joints as it will act as a seal.

2. Using vegetable oil, lightly grease all surfaces that will be in contact with concrete.

3. Assemble the mold by placing the 2 sides, the back, and the front panels of the mold on the interior mold. There should be a mark on the bottom of the interior mold to indicate on which side the nose (front) panel goes.

4. Insert all bolts, leaving them loose. 5. Ensuring that the upper edge of the mold is as square as possible, hand tighten all bolts. 6. Tighten all bolts with a wrench.

7. Place the standpipe into the mold with the 180° bend down. That bend must come up and out of the nose. The other bend N:\Training Material\Training tools\Appendices to Manual\G (2) – 330 Lb Concrete Filter Construction Manual.doc

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must sit flush against the interior mold.

8. Place the nose plate on the nose of the mold, with the PVC pipe just sticking through the hole. 9. Tighten the set screw to hold the nose plate in place. 10. Place a wooden wedge between the upper end of the standpipe and the mold to hold the standpipe in place.

11. Cover or plug the outlet of the standpipe with paper or a rag so that no concrete gets in it. 12. Use a level and wooden shims to make the mold level.

POURING THE FILTER Estimated Time: First attempt – 1 ½ hours, with practice – 30 minutes Tools Needed: • 1 length of rebar • Two ¾” wrenches • Mallet • Wooden shims of various sizes • Trowel •

Buckets for measuring sand, gravel and cement

1. Measure 1 part Portland cement, 1 part sieved sand, and 1 part ½” gravel. (This is the gravel that was collected by the medium (¼“ or 4 gauge) sieve. Note: This mixture will set in about 20 hours and permits the production of one filter per day from each mold. If less cement is used, the setting time may increase. Use of different cements will also change the set time and may cause leaks of lime or gypsum, which can result in a cracked filter. 2. Mix dry ingredients together thoroughly.

3. Add water gradually while mixing to make a fairly stiff mix (cookie-dough consistency).

4. Shovel concrete into the mold, a few shovel-fulls at a time.

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5. As each layer of cement is added to the mold, use the rebar as a tamper to ensure the concrete completely fills the area without any voids. At the current level of the concrete, hit the outside of the mold on all sides, including the nose, with the mallet in an upward pattern. (The vibration allows air pockets to escape the concrete.)

6. As you fill the last of the mold, check the nose plate and standpipe to be sure that the pipe has not moved and do not disrupt the wooden wedge which holds the standpipe in place.

7. Fill around the wooden wedge. Heap extra concrete on top of the mold (forming a bulge) as there will be some shrinkage.

8. After 10 minutes, remove the wedge and use the heaped concrete to fill the space. Jab your trowel 4” into the concrete, all around the inner mold, to ensure that the final layer mixes with the previous layer.

9. Smooth away the excess concrete with a flat board and then trowel it, to leave a flat surface (which will be the base of the filter).

10. Do not leave the filter in the mold for longer than 24 hours. REMOVING FILTER FROM MOLD Estimated Time: 45 minutes Tools Needed • Two ¾” wrenches • One 1 ½” wrench •

One block of wood

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One hammer Wooden spacers Soap & scrub brush or broom

Within 18 to 24 hours, remove the filter from the mold, as follows: 1. Loosen the set screw and remove the nose plate. 2. Turn the mold on its side, laying it on a tire or a sack of grain.

3. Continue turning the mold until it is resting on the concrete face of the filter. The mold is now upside down compared to how it was before.

4. Remove the bolts on top of the mold. Do not loosen any of the side bolts yet. N:\Training Material\Training tools\Appendices to Manual\G (2) – 330 Lb Concrete Filter Construction Manual.doc

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5. Hit the top of the mold with a mallet (or use a block of wood and a hammer), to loosen the bond with the concrete.

6. Position the puller assembly on top of the mold. Each rod of the puller should sit in the corresponding slot on the inner mold. Note that the nut on the central bolt should be well above the square tubing. 7. Tighten the centre bolt (by turning the bolt clockwise) until the bolt is well threaded into the nut on the mold.

8. Tighten the central nut (which sits above the puller assembly) by turning it clockwise. Turn the nut down until it contacts the puller assembly and then continue turning, which pulls upward on the interior mold until it releases. Note: If the mold starts to bend, stop what you’re doing immediately. Undo all bolts, remove the exterior panels and break the concrete off of the interior mold. Do not damage the mold for 1 filter.

9. Continue turning the central nut until the interior mold is entirely released. 10. Place wooden spacers between the exterior mold and the interior mold. 11. Loosen the nut on the puller assembly until the interior mold rests on the wooden spacers. 12. Remove the puller assembly.

13. Carefully remove the interior mold and place it in a safe location. 14. Remove the remaining bolts and the side and back panels. 15. Remove the front (nose) panel. You may need to tip the filter back and place a wooden shim under the front edge, and then use a hammer and small pry bars to detach the front panel. 16. Clean and oil the mold.

17. Check the two ends of the standpipe to ensure they have not been plugged by concrete. Remove any visible debris until you can clearly see or feel the outlet at the bottom of the filter.

18. Fill the filter with water to be sure that water flows through the standpipe. 19. Check for cracks and flaws in the filter.

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20. Fill the filter with water (or at least keep it moist) for five to seven days while the concrete cures. Do not transport the filter any significant distance during that time. 21. Put a small amount of soap in the water that was sitting in the filter, and scrub the inside of the filter out with a broom or scrub brush.

#12, 2916 – 5th Ave N.E. Calgary, Alberta, Canada T2A 6K4 Telephone: (403) 243-3285 Fax: (403) 243-6199 Email: [email protected] Website: www.cawst.org

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