Terren Landscapes http://www.terrenlandscapes.com 2014 PLNA Awards for Landscape Excellence Winner Category: Residential $60,000-$120,000 Award Level: Silver Project Description: We were contracted by the family to create a master plan for the property. They were experiencing extreme drainage and erosion problems due to the surrounding properties’ drastic grade changes. Erosion had caused the rear lawn to sink in various areas and the existing rear patio spaces were failing. The client wanted to rebuild their patios and walkways, repave their driveway and give their home more visual appeal. Most importantly, they wanted an environmentally friendly solution. Our design solution was to create a rain garden that would slow storm water runoff, allow for percolation, and promote infiltration, while permitting excess clean water to enter the storm drain at the street with slower velocity. The rain garden acts as a temporary holding space that allows the earth to slowly absorb water, rather than overwhelm the nearby storm drain. Our first objective was to conduct a percolation test to determine the amount of clay soil that needed to be removed before reaching the sandy loam layer. A percolation test and storm water calculations were generated to accommodate a 1” rain event. Based on our calculations and the small size of the property, we determined a depth of 18” was necessary for optimal holding capacity. We removed 18” of clay soil until a layer of sandy loam was encountered. Next, the soil was amended with compost and sand to create a highly porous planting media for the basin of the garden. We piped the three existing rear downspouts to the rain garden area to capture for infiltration and alleviate runoff throughout the rear lawn and patio space. We installed an 18” wide over-flow standpipe at a 24” depth into the ground that outlets to a stone swale that carries the water to the property edge. As an added means of holding the maximum amount of water, we designed the standpipe to sit 14” above grade. The height of this standpipe allows this rain garden to capture 14” of water before reaching the overflow capacity. We placed geotextile fabric to help reduce migration of the stones into the soil and aid in the prevention of weeds and erosion. We heavily planted the rain garden to further aid in absorption and to attract local wildlife. A native plant palette of butterfly weed, Panicum, Joe-Pye weed, and asters form a colorful backdrop while the basin was filled with obligate wetland plants such as royal ferns, irises and cardinal flowers. The upper edges in the foreground are planted with Echinacea, Rudbeckia and Monarda, satisfying the local bird community and adding bright seasonal colors. This garden effectively collects and cleanses rainwater while creating a habitat for birds, frogs, and butterflies. Our next challenge was to redesign the existing patios and walkways without increasing impervious surfaces. According to township regulations this property was currently at its maximum capacity, therefore we designed the front and rear patios with a slightly smaller footprint to decrease their existing impervious surfaces. New planting beds were designed throughout the entire property. Plants were chosen that were tolerant of specific site conditions. For the rear yard, we choose a backdrop of witch hazel and hollies to provide an evergreen screen as well as early spring color. We placed hydrangea throughout to add summer color. We planted ostrich fern under the existing spruce tree to create a lush floor. This area became an additional backdrop for the rain garden as well as a screen for the neighboring property. We choose a combination of ‘Blue Star’ juniper and creeping jenny to soften the existing rear wall with creepers. Around the rear patio areas we choose a combination of Liatris, Rudbeckia and ‘Lo and Behold’ butterfly bush. This combination of plants works in harmony with the rain garden and attracts additional butterflies. For the front of the property we worked with an existing Japanese maple that provided dense shade. We choose a shade-tolerant combination of Heuchera, Astilbe, ferns and hostas for this area. We added more hydrangeas to the front foundation of the house to provide lush layering of plant material and visual interest with additional summer blooms. Overall, we were able to exceed the client’s needs and expectations in transforming their property into a colorful paradise that attracts wildlife from season to season. The plant palette provides seasonal interest and the rain garden has successfully decreased storm water runoff. The new hardscape surfaces were designed and built with a slightly smaller footprint to decrease impervious surfaces. This project is a positive example of how all properties, regardless of size, can make an ecological difference by decreasing impervious surfaces and maintaining proper storm water management. Photo Credit: Terren Landscapes