Monday, March 4, 2019

Waterfront Swales with a Hugelkultur and Dune

Run-off area
At this residential property on the Maryland coast, I was tasked with designing a native landscape to manage polluted stormwater coming from the road, running down the driveway, across the lawn, and ultimately exiting into a cove on the Chesapeake Bay. 

Due to underground utility lines and space constraints, the only location for this new device was at the waterfront. 

Beach litter collected for Hugelkultur

Waterfront site, BEFORE

My design consists of two adjacent swales and berms. The level swales are filled with wood chips, which act as a sponge, collecting the stormwater and enabling it to percolate into the soil, interrupting its journey to the bay. The plant roots at the berms absorb this water as passive irrigation. 

Installed in October, the upper berm was constructed as a hugelkultur, mounded with harvested beach litter (drift wood and seaweed) and covered with the soil excavated from the swale above. My client had already imported sand to make an artificial beach, and asked me to construct the lower berm as a dune.

Berms and swales under construction
Mimicking the local coastal plant community, the upper berm was planted with native shrubs that tolerate brackish water, some growing in the wild area right next door. Their woody roots will anchor the soil against the deluge of stormwater during harsh storms, and buffer strong winds off the Bay. These shrubs also create privacy for the beach by blocking the view from the road. The Southern Bayberry fixes nitrogen in the soil. 

Before planting; after the first rain
In a functional landscape, every component serves at least one purpose, besides providing beauty. The dune was planted with local, salt tolerant grasses and flowers, which will attract beneficial insects like bees and butterflies.  To create a gentle transition between this native landscape and the lawn, I added some non-native aromatic herbs and ground covers. These will deter mosquitos, and eventually negate the need for mulch. 

Finished Rain-scape; swales filled with wood chips (winter)
Fall is a great time to plant because new plants can go dormant while their roots establish over the winter.  There is no stress from hot summer temperatures or the need for daily watering.  When spring comes the following year, plants stand of better chance of thriving without constant attention

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Monday, January 7, 2019

A Native Edible Riparian Buffer

Volunteers planting live stakes into the river bank.
Last spring I designed a riparian edge for a Gunpowder Valley Conservancy Bayscape Program participant whose lawn borders the Gunpowder River in Kingsville, MD.  Our objective was to restore the eroded river bank by planting trees and woody shrubs to hold the soil in place.  Two existing Pin Oaks, and a Quince (shrub) were preserved.

Live Red Twig Dogwood stakes were planted directly into the stream bank by making 18" holes with a steel rebar.  These will create a brilliant splash of color in the winter time.

Native edible trees and guild plants 
Native trees and woody shrubs were planted at the top of the bank.  These included a beautiful Red Bud (a nitrogen fixer), and edible Paw Paws and Common Persimmon.  Red Elderberry and Sheep Laurel and provide the shrub layer.

An herbaceous guild supports the edible trees with delicate Eastern Columbine (another nitrogen fixer), Wild Bleeding Heart (a beneficial insect host) and Nodding Onion (a dynamic accumulator), plus shade-loving Green and Gold, Cinnamon Fern (with edible fiddleheads) and Christmas Fern. Existing moss was left intact.

To give these native trees and plants a jump-start and increase their root mass, we added a microbial mycorrhizae innoculant to the soil.

A fully effective riparian buffer would need to extend at least 50' in depth from the stream in order to successfully filter sediment.  However, by replacing lawn, this demonstration riparian buffer, once established, will help stabilize the river bank, patch a hole in the wild life corridor, and provide fresh, organic, autumn fruit for the property owners.

Gunpowder Valley Conservancy volunteers with the finished project.

For more information visit my website at: