If you live in an area where you frequently experience water backing up into your basement or flooding you might need a way to remove excess runoff. Rain gardens are a beautiful and sustainable tool for storing and absorbing water away from the structure of your home. They also capture surface runoff from roofs and streets absorbing pollutants and excess water, lightening the load on your city's sewer system as well as reducing potential sewer overflows. Even more importantly, rain gardens utilize native plants encouraging the presence of bees and butterflies to the gardens.
This Instructable demonstrates how to build a rain garden on a small and affordable scale allowing you to visualize how water moves through the garden and even implement soil moisture or other sensors to monitor the behavior of the garden.
Step 1: Materials Required
- 7 Quarts of Mulch
- 28 Quarts Compost
- 31 Quart Soil (fine sand, coarse sand, pea gravel, etc.)
- 66 Quart Clear Storage Container
- 34 Quart Clear Storage Container
- 5 Supports (ex. cups filled with sand, PVC pipe, etc.)
- 5 Gallon Bucket
- 16 inches 1” PVC Pipe
- 1” PVC Slip Elbow
- 1” PVC Tee
- PVC Ball Valve
- PVC 90° Elbow
- Drill with 1" Bit
- Weed Barrier
Step 2: Mixing Engineered Soil
To simulate the rain gardens built in the field, we will be engineering our own soil mixture in this experiment. We used different soil mixtures since different soils have different percolation rates and holding capacities. Simply, some soils are better at moving water through the garden faster than other. Additionally, some soils have larger gaps between the individual particles and can store more water.
- With the one quart container, add 7 quart of soil to a larger container.
- Next, add 3 quarts of compost to the large container.
- Continue with this method until you have a total of at least 44 quarts of engineered soil.
Step 3: Building the Downspout
- Cut one 9.5" and one 6.5" length piece of PVC pipe.
- Attach the 6.5” length piece to the bottom tee slot and the elbow PVC connector.
- Attach the 9.5” pipe to the other end of the elbow joint.
Step 4: Building the Garden
Begin constructing layers of the rain garden to simulate an engineered rain garden.
- Add 22 quarts of 70-30 soil compost mixed engineered soil to create the bottom most layer. Pat down and shape into a slight bowl shape.
- Add another 22 quart of the mixed engineered soil to represent the second layer in the rain garden. Again, shape slightly into a bowl shape.
- Place downspout in the center of the garden on top of the second layer of engineered soil. Make sure the tee connector rests in the middle of the garden.
- Add 28 quarts of compost on top of the two layers of engineered soil and level out across bottom layers making sure to cover the downspout.
- Add the final 7 quarts of mulch to the top layer spreading evenly.
- Place assembled rain garden in 66 quart container into 34 quart container. Make sure to align supports and get assistance as the assembled garden becomes rather heavy.
- Add any sensors you may want for the test and the garden is now ready to test. The funnel is very helpful when adding water to garden through the 1” PVC pipe.
Step 5: Creating the Catch Basin
- Drill one hole on the short side of the 34 quart container and attach the plastic valve to eliminate water.
- Sealant may be necessary to secure valve and prevent leakage.
- Add 5 supports, one in each corner and one in the center, to hold the weight of the simulated rain garden.