This September, our vet crew finished the second phase of some work we were doing at Bay View United Methodist Church in Mount Vernon - http://www.bayviewumc.com/. The church sits near the shoreline of Padilla Bay, just south of Bay View State Park, in a picturesque neighborhood. We had already completed a rain garden under the first phase of the project. The second phase was to slow upland flow from a neighboring residential area, and to get most of it to soak into the native soil before it reaches Padilla Bay.
This property presented unique challenges to our team and was fun to bring to fruition. A nearby man-made slope was eroding sediment onto the church property. During a June site visit, we discussed the idea of terracing the slope and planting it. The terracing slows the water coming down it, and the plants prevent the soil from eroding. We decided to do a special type of terracing using a product called “compost filter socks”.
A compost sock is a long tube made out of very strong fabric. We used a product made by the company Filtrexx - https://www.filtrexx.com/en. The sock is filled with medium-coarse compost and it makes a 8 inch diameter tube that is about 10 feet long. The filled socks are snaked into a nice curvy wall that is quite effective at making terraces on slopes.
The sock walls were back-filled with a high compost soil, and that soil was covered in a very coarse mulch. The soil will be planted, but the cool thing about compost socks is that they can be planted, too. Small holes are cut into the sock fabric and kinnikinnick is planted into the compost within the sock. The kinnikinnick will eventually grow to cover the entire sock and the terraces become a living wall.
The final result is a terraced garden with a series of living walls that prevent erosion and slows and filters uphill stormwater.
Use your imagination and you can visualize that this is what those rows of composting socks might look like in the future. Here are some examples from an Everett property where the compost socks have provided a nice base and the Kinnikinnick has grown in nicely.