Three-Star Certified Pilot Project
Location: Kennett Square, Pennsylvania
Project Size: 1.69 acres
Project Type: Residential
Site Context: Suburban
Former Land Use: Greyfield
Terrestrial Biome: Temperate Broadleaf & Mixed Forests
photo by Mark Gormel
This 1.69-acre residential property and former dairy farm boasts a drip irrigation septic system that handles sensitive wastewater disposal while preserving hillside woodland vegetation, and green roofs that absorb rainwater and reduce peak stormwater surge while regulating building temperature. Additionally, the site includes a designed stormwater system that uses best management practices to direct and control storm water flow, recharge ground water, reduce peak stormwater surge, and create aesthetic landscape features. The relatively steep slopes on the project site initially posed challenges for water management, as well as the ability to site improvements. However, this became an opportunity to demonstrate creative water management techniques. Improvements including, stone and vegetation lined swales, below grade cisterns, Hugelkultur devices, soil berms, green roofs, holding wet ponds, and rain gardens were worked into the slopes creating terraced rooms and unique garden spaces. In December 2012, after hurricane Sandy, there were no signs of soil erosion on-site for the first time since 1993.
Other unique features of the property include native woodlands and meadows, a potting shed built from salvaged materials, culinary planting beds, a meditation labyrinth, whimsical sculptures, and a straw bale hut.
The property is located along an eastern slope of the mid to lower Piedmont region of Pennsylvania and is characterized by largely wooded, low rolling hills and steeply incised stream valleys. It is a transitional area between the mostly mountainous Appalachians to the west and lower, more level ecoregion of the coastal plain to the east. In the area, elevations range from 200 to 1,000 feet. The Piedmont region is underlain by deeply weathered, deformed metamorphic rocks. The sites' Glenelg and Manor upland soils developed from weathered granite, gneiss and mica schist, and are moderately deep to shallow, and well drained. Terrestrial plant communities typical for the site include Dry Oak Mixed Hardwood Forest, and Little Bluestem, Pennsylvania Sedge Opening, and Side-Oats Gramma Calcareous Grassland. These communities are supported by a warm, humid, and temperate climate receiving on average 45 inches of rain annually.
SITES Features + Practices
The site has four primary features that demonstrate the principals of sustainability.
- A drip irrigation septic system that disposes of wastewater while preserving hillside woodland vegetation.
- Green Roofs that absorb rainwater and reduce peak storm water surge, while regulating seasonal temperatures inside of structures.
- A Rescue Garden using repurposed, excavated materials that otherwise would be sent to a landfill. Handrails from the house's former porch became a garden fence, and the porch's timbers were adapted to construct a one-of-a-kind potting shed. Twenty-five tons of stone unearthed during construction found new life as steps, terraces, roadways, and retaining walls, and excavated soils were used to create ramps and planting beds.
- A stormwater system using best management practices (BMPs) to direct and control storm water flow, recharge ground water, reduce peak stormwater surge, and to create aesthetic landscape features and habitat.
The following codes, zoning, and regulatory requirements influenced design decisions regarding this project:
- County and Township Sewer Management Code: The primary influence on the site design was the need to upgrade the site's septic system. County/Township requirements dictated the system needed to be 100' from the site's well. With other planned improvements, and need for heavy equipment access, the only feasible location was the hillside woodland above the house. In interest of preserving the woodlands, the owner elected to construct a drip irrigation system woven in and around existing trees and shrubs in the adjacent area.
- Township Stormwater Management Ordinance: Stormwater management requirements for planned improvements drove the design of the lower portion of the site to become a significant water management feature capable of holding the required volume of stormwater runoff.
- PennDOT: The transportation department dictated the location of the shared driveway spur and eventual layout of the entry drive.
- Township Scenic Resource Protection Plan: The plan inspired the development of a vegetation system with a lower meadow characteristic consistent with the historic and cultural norms for the area. The planned inclusion of a spring house will further develop the area's aesthetic and historic vernacular for "Chester County, PA."
- Townships Steep Slopes Protection Ordinance: This ordinance placed ultimate limitations on the planned site improvements.
- Township Subdivision and Land Development Ordinance: This ordinance restricted the placement of improvements to designated building areas. Since the house was built before lot boundaries were defined, the ultimate size and placement of additions were constricted to the historic house location.
The Design Team's focus on water and soil management drove the design, construction, and planned maintenance responses for the project. A 100-year rainstorm in December 2012 demonstrated the appropriate and adequate design and placement of all stormwater devices. After hurricane Sandy and for the first time since 1993, there were no signs of soil erosion onsite. In addition to the Design Team, Stakeholders provided significant support with site design, selection of reference plant communities, and most notably development of site's operations and maintenance plan.
Maintenance + Stewardship
The primary management goal for the project site is to create a 55-hour garden, a garden that only requires 55 hours a year to maintain. Inspired by a local and notable horticulturist, Dr. Richard Lighty, the owner intends for nature to maintain the site and restore ecosystem functions to reduce the amount of time needed to manage the upkeep of the garden. Healthy soils will support native vegetative communities and managed stormwater will flow through the site without harm to designated recharge areas. The owner anticipates it will take approximately 3-5 more years to achieve this goal, in part because some improvements are yet to be constructed. However, within 2-years after the removal of dominate invasive and non-native plants, both the Hillside and Pleasure gardens already take less time to maintain, leaving more time for leisure/play in the garden.
At end of a 2-year monitoring period, in June 2014, the owner will draft an article/ summary report on soils, vegetation, and stormwater management performance. Monitoring protocols include:
- The owner keeping a maintenance activity and time journal.
- Losco and the owner testing soil, annually in the spring.
- Ebert, West, and the owner conducting an annual review of vegetation in September. Stakeholders will be invited to participate on site walks.
- The owner keeping photo records of plant community development and invasive plant removal activities.
- Williams and the owner conducting an annual inspection of the stormwater system/ devices in the spring.
- The owner keeping monthly photo records of the project's stormwater management devices.
The owner is committed to using the project site as a model for sustainable landscape practices in her community and region. Meeting the goals set forth at the beginning of the project is necessary to retain professional credibility. Through speaking engagements, educational outreach, and site tours SITES goals will be showcased for review and scrutiny. To be successful and able to compel others to convert to sustainable landscape practices, the project goals will be maintained. Per the owner's understanding, a municipality in Pennsylvania is adopting a model ordinance that aligns with SITES Benchmarks and Standards. Discussions have occurred in Kennett Township about doing the same. With the right leadership it could possibly result in the adoption of an incentive program for building sustainable landscapes.
The biggest challenge of the redesign was the historic use of the property as a farm, which stripped the site of its native plant communities and topsoil, and left highly eroded and compacted soils. In addition, after the farm stopped operations, much of the equipment and structures were buried on the site and had to be excavated.
These challenges lead to the greatest opportunities including rebuilding soil health, reestablishing native plant communities, and repurposing buried materials on the site. Excavated materials have been transformed into new stonewalls, structural road supports, drainage ways, and creative landscape amenities and follies.
Also, the 8-15% grade of the site posed challenges for stormwater management. This developed into opportunities to demonstrate creative water management techniques to direct, capture, and slow runoff. Improvements were worked into the earth as terraces, creating unique garden spaces.
Project Goals + Successes
The main goal of this residential design project was to become a landmark demonstration site and educational resource for sustainable land management practices, including:
- Efficient management of water resources across the site to preserve the quality and quantity of water resources in the area.
- Restoration of native plant communities to support preservation of biodiversity and ecosystem health.
- Protection and restoration of topsoil resources and health.
- Use of regionally sourced soils, aggregates, plants, and other materials/products.
- Use of landscape practices that model natural processes and minimize long-term management requirements.
- Implementation of site management practices that consider a balance between economic, social and environmental needs.
- Preservation and enhancement of the Cultural and Significant Visual Resources within Kennett Townships.
- Creation of outdoor living spaces that bring pleasure, engagement, and spiritual rejuvenation to all users.
As mentioned above, the site was designed to act as a community demonstration and educational resource for sustainable land use practices. Therefore, it became important to consider accessibility to garden areas for visitors of limited mobility and groups of varying sizes. A pathway and signage system was designed for users of all abilities. Visitors can arrive, gather at the sacred grove, hear a brief overview of the project, receive a map, and explore the garden on their own. As interest grows, resources will be developed for additional educational programs.
Since the project began before the SITES Pilot Program was launched, some past decisions needed to be adjusted in the field to align with SITES protocols. Other decisions needed to be qualified or quantified post completion such as the amount of soil moved and repurposed for the new driveway. In addition to the owner, the success of this project should be credited to the contractors, suppliers, stakeholders, and design team for their flexibility, willingness to change in mid-stream, and timely humor.
Working through the SITES process has fostered a greater awareness and knowledge about sustainable development practices. The owner and design team have a better understanding of the process and resources available, and how to implement sustainable strategies in the appropriate sequence. Particularly the importance of determining long-term management needs and costs during the design phase of the process.
Margot S. Taylor, RLA, Owner, Landscape Architect, SITES Project Manager, Land Ethics
S. Edgar David, MLA, RLA, Landscape Architecture, CAD maps and illustrations, SED Design Studio
Russell L Losco, MA PG, CPSS, Soil Scientist, Lanchester Soil Consultants
Carol W. Ohm, PE & Stephen E Williams, PE Civil Engineering, Apex Engineering, Inc.