EPA Region 7 Headquarters

Most of the green infrastructure was initially installed in 2007 for the corporate campus development, but the EPA needed to make Level 4 security enhancements on the property without negatively impacting existing green infrastructure or established native landscape. The original courtyard and landscape zones immediately adjacent to public paths relied on irrigation, and the EPA required modifications in order to pursue LEED-EBOM Platinum certification. Project designers faced the added challenge of implementing these measures in a way that was aesthetically pleasing. 

Solution

Each portion of the site was analyzed for its security risks. The west side is the entrance to the EPA headquarters and is primarily composed of parking lots. Drop-arm gates were added to lanes leading up to the building to control access. Parking areas were lined with limestone blocks that serve as vehicle barriers and appear more natural than fences or concrete K-barriers. The north and south sides of the site are open fields in which car catchment zones were installed as deep ditches to prevent vehicle intrusions. Steep side slopes and narrow bottoms prevent vehicles from crossing the ditch. Using native grass fields and limiting turf grass met the aesthetic requirements of the project while allowing it to earn LEED points for reducing potable water use for irrigation.

• A series of stormwater best management practices (BMPs), including bioswales, rain gardens, sediment forebays, a sand filtration basin, and a constructed wetland, redirects and filters 60.7% of on-site runoff , as well as off-site stormwater from an adjacent 5.2 acres from Renner Boulevard that is piped to the wetland for treatment.
• Runoff from the parkikng lot is filtered by 20-ft-long terraced bioswales with a 10-ft-wide fescue filter strip on the collection side and native plantings on the backside. 
• A 3,000-sf central rain garden predominantly planted with blue flag iris, blue lobelia, marsh blazing star, New England aster, false dragon’s head, common rush, and fox sedge leads to the main entry of the building and collects runoff from the adjacent parking lot before it inlets toward the southern sediment forebay.
• Sediment forebays are a critical first step in stormwater treatment, trapping sediment and debris as it travels through the treatment train.
• A 7,100-sf sand filtration basin treats over half of the site’s runoff and reduces total suspended solids.
• A constructed wetland serves as the final stage of the treatment chain.
• 3 courtyards on the eastern side of the building feature rain gardens which treat roof runoff and, depending on the courtyard, include a turf amphitheater, native and adapted plantings, a tree bosque, and moveable furnishings.
• Buffalograss covers more than 50% of the area around the building, along with taller stands of sideoats grama, little bluestem, and prairie dropseed. These native grasses minimize maintenance, fertilizer, and water requirements while providing seasonal color and textural interest.
• 4 Johnson County bus routes are accessible on streets bounding the EPA site. The provision of 33 bicycle spaces along with the site’s accessibility via public transportation encourages employees to use alterative modes of transportation.
• Of the 610 on-site parking spaces, 31 (5%) are reserved for Low Emission (LEV) and Full Electric (FEV) vehicles, while an additional 31(5%) are reserved for carpool and vanpool vehicles.

The estimated installation cost for the native landscape was 44% less expensive than comparable turf and irrigation, with the native landscape estimated at $619,097 ($32,670 per acre) and the traditional turf landscape at $1.1 million ($58,332 per acre).

The estimated installation cost for the green infrastructure stormwater treatment train was $340,933. For similar site conditions, building a traditional detention basin was estimated to cost $311,335. Although slightly more expensive, the green infrastructure treatment chain provides additional water quality and aesthetic benefits.

• A common misconception of native landscapes is that they require no maintenance. While native landscapes do require less overall water and maintenance than traditional ornamental landscapes, regular maintenance is still necessary. In the case of the EPA project, property managers and landscape architects created specific bid documents detailing establishment and maintenance requirements for the native landscapes. This specificity is necessary if landscape maintenance companies are less experienced and are unclear about the monthly maintenance required to support the establishment of a native landscape.
• Significant erosion took place upstream of the BMPs and around the BMPs during the first years of establishment. It would have been better to install and establish BMPs upstream to downstream, with the wetland established last after the site was fully stabilized and vegetated to prevent sedimentation.
• Geese and other animal droppings contributed to water quality degradation of the wetlands. High levels of E. coli bacteria were present during the first two growing seasons. Since geese prefer open sight lines to avoid potential predators, geese could be discouraged by planting tall and dense emergent vegetation around the edges of the wetland and maintaining narrow widths of open water. Expected results after establishment should show near zero E. coli.
• According to the 2011 “Multi-Variate Study of Stormwater BMPs Final Report,” the 800-cu-ft capture volume of the rain garden for the central courtyard was undersized for the roof runoff volume of approximately 1,560 cu ft for a design storm event of 1.37 in. The flow volume and short garden runs of 124, 100, 75, and 60 ft meant that the water-plant contact time of 5 minutes or less did not allow much time for pollutant removal. However, the soil remained moist and the plants grew well.

Native and Ornamental Trees, Shrubs, Grasses, Sedges, and Rushes: Rosehill Gardens
Bioswale Plants: Critical Site Products, Fox Sedge Deep Cell Plugs and Seed
Native Turf Seed: Critical Site Products, Buffalograss seed ‘Bowie’
Unmowed/Un-Irrigated Fescue Grass: Critical Site Products, K-31 Fescue seed
Cover Crop: Critical Site Products, Regreen Sterile Wheat
Planting Soil Mix: Missouri Organic Recycling
Erosion Control Blanket: Greenfix America, LLC, Type CFS072B (biodegradable)
Hydromulch: Phoenix Paper Products, Green Choice Premium
Mycorrhizal Inoculum/Soil Conditioner: Gro-Power, Inc., GroLife
Prairie Grass Soil Amendment: Gro-Power, Inc., Prairie Formulation 0-3-1
Fertilizer: Southern Organic & Supply, Nutri-Cast
Filter Fabric: Propex, Geotex 401
Water Monitoring Equipment: Teledyne ISCO, Inc. Model 6700/6712 with 730 Bubbler Flow

Project Team

Landscape Architect and Architect: BNIM
Property Owner: Lexington LAC Lenexa, L.P.
Property Manager: Lane4 Group
Tenant: Environmental Protection Agency Region 7
Civil Engineer: Shafer Kline & Warren, Inc.
MEP Engineer: Lankford & Associates
Fire Protection: FP&C Consultants
Structural Engineer: Structural Engineering Associates, Inc.
Security Engineer: Walter P Moore
General Contractor: JE Dunn

Role of the Landscape Architect

The landscape architect was the site designer for both the original corporate campus and the EPA Headquarters and was responsible for all site design services associated with design of the parking lot, security, stormwater system design, courtyard improvements and landscaping. Completed tasks included oversight of all civil engineering scope, LEED construction management, and construction administration services.