Introduction
Chagrin Falls, Ohio is a picturesque village of 4,000 residents sitting at the edge of Cuyahoga County, east of Cleveland. The town, named for the scenic falls in the center of town, is known for its historic architecture, varied restaurants, interesting antique shopping, art galleries, and its vibrant arts community. This setting provided a unique opportunity to develop a proposed office site, which responsively merges with its context of neighboring offices in the village, and the natural environment. The new Cawrse & Associates, Inc. office site enhances the office district as a compact and sustainable area, and combines architecture and contributions to the existing natural environment, while connecting to the larger urban context.

The need
Cawrse & Associates, a 30-year-old Chagrin Falls Landscape Architecture and Land Planning firm, required a larger and updated facility for their practice. They selected to develop the rear portion of their property, directly behind their former office, with a new office building. The proposed Cawrse office site is located on a 2.4-acre parcel of land, on which 0.4 acres is occupied by their present office building. The newly constructed office site is 0.6 acres and contains a bio-swale, bio-detention basin, a rain garden, and 8,000 square feet of permeable interlocking concrete pavement (PICP). The proposed office building structure is approximately 6,400 square feet, which incorporates an innovative stormwater runoff system that captures rainwater from roof downspouts, and pipes it directly into the nearby rain garden. The remaining 1.4 acres of the site is open space, and will remain as an undisturbed, naturalized area, protected by a conservation easement, and will serve as a buffer to the adjacent residences. This conservation area will be enhanced by plantings within the bio-swale and bio-detention basin.

The Cawrse & Associates office site protects the developed, and undeveloped, areas of the property by utilizing a detailed stormwater management system, conserves the surrounding vegetation and open space, and assures water quality, reduced runoff, and stream preservation. The grading and plantings allow the site to harvest stormwater and feeds it into the nearby rain garden and bioswale. The porous pavers combine hardscape infrastructure and water permeability, recharging the ground water. The site plan establishes a riparian buffer, which will remain in perpetuity.

Cawrse & Associates are landscape architects and land planners, and their focus for the project was to develop a sustainable site plan. They wanted an office site that would protect and enhance the property, reduce stormwater runoff, reduce heat island sink by using lighter-colored pavement, and provide a demonstration platform that incorporated as many low impact site elements as possible. The only concession that was made was for the stormwater calculations. Normal pavement (non-porous) run-off coefficients were used, in lieu of lower “porous” values, so that the storm basin would have added stormwater volume for storage. This would ensure that the sensitive downstream areas would be further protected from runoff and siltation, whereas these areas had been severely impacted for many years previous. Because of this approach, the Chagrin River Watershed Partners, Inc. awarded Cawrse & Associates a grant for the project to help defray the cost of the proposed porous pavers, rain garden, bio-swale and bio-detention basin.

As the new Cawrse office site is an extension of the existing office, the site design allowed for opportunities to minimize infrastructure connections by utilizing shared utilities to the new structure, and shared vehicular entry from East Washington Street that minimized curb cuts. The porous paver parking lot created a permeable surface, reducing runoff, and the impact on the stormwater system by allowing stormwater to percolate into the ground, thereby recharging the water table.

In the development of the office site, the design conserves resources and energy by incorporating minimal site disturbances, with less clearing and grading, and by using native plant materials. The habitat was be restored and will be maintained by implementation of a three part maintenance program, which will oversee plantings, pavement, planting soil mixes, gravel riffles and rock weirs. This maintenance will assure water quality and lowered water runoff rates. The native plant palette also encourages low maintenance and water efficiency. For example, a no-mow seed mix will be used on most lawn areas, and the plant material will require little if any pruning or continued upkeep.

The design

Innovative Storm Water Management System Key Site Design Elements (refer to plan)

1. Permeable Pavers – 8,000 square feet Unilock Eco-Optiloc permeable paver parking lot. This paving surface allows all storm water to infiltrate through the pavement, be detained within the base material, and then infiltrate naturally into the groundwater aquifer. Excess filtration is diverted into subdrainge piping and discharged into the bio-swale.

2. Rain Garden - Captures roof runoff from the building downspouts that is piped directly into the rain garden to recharge the groundwater through infiltration and filtered by the roots of water tolerant native plants.

3. Bio-Swale – Receives site and subdrainage runoff, which slows the water through native plantings, gravel riffles and rock weirs to increase infiltration, prior to reaching the bio-detention basin. The sides of the swale are planted with a no-mow seed mix and a low maintenance, water efficient, native plants.

4. Bio-Retention Basin - A semi-wet pond that includes forebay, mudflat and saturated areas with native plants placed according to the wetness conditions. The native plants absorb, and filter the water. This allows much of the storm runoff to infiltrate on site instead of flowing down stream. The perimeter of the basin is planted with a native no-mow seed mix.

5. Open Space/Conservation Easement – This area will remain undisturbed, which will allow the natural drainage flow to remain uninterrupted and the ground to remain as a pervious surface.

The parking lot is a straightforward center drained design with the pavers base being 14” of 70% compacted No. 57 crushed, washed aggregate stone, while the pavers are set on 2” setting bed of No. 8 course aggregate and the same material is brushed in the pavement joints. Any water that does not infiltrate the subgrade will enter a 4” perforated pipe, which runs down the center of the drive lane. This pipe then outlets into the bio-swale, which drains into the bio-detention basin. Flush concrete curbing contains the pavers around the perimeter of the parking lot. We worked together with the paver manufacturer and the paver installer to carefully review details and construction methods since this system is not widely used in this region, and this is a demonstration project that will be viewed closely by many local agencies. For the front entry walk a solid paver pattern was used with a combination of granite topped and brushed finish pavers, which complimented the stone building façade.

Chagrin River Watershed Partners contribution to the sustainable site design The Chagrin River Watershed Partners, Inc. (CRWP) is a non-profit technical organization, founded for the Chagrin watershed, centers on improving the rules of development by assisting Members in implementing regulations that maintain the flood control, erosion control, and water quality protection function of the Chagrin’s riparian areas, wetlands, and open spaces, while facilitating innovative new and redevelopment practices.

This project includes technical support, education, and funding to design, construct, and monitor four low impact development demonstration projects. Information gathered from these demonstrations will address concerns about the role of soils, climate, and maintenance in the applicability of these practices to Ohio.

The Cawrse and Associates, Inc. office building located in the Village of South Russell demonstrates low impact development practices for new building construction. The CRWP’s involvement with the permeable interlocking concrete pavement (PICP) system from the onset was key in a variety of ways. The project goal was to mitigate storm water runoff from a new private office building and parking area, and using a combination porous pavement, bio-swale, rain garden and bio-detention that would help accomplish that goal.

Design and construction of all four demonstration projects was completed in 2008, and CRWP has started a two year monitoring program to measure water quality and and quantity parameters. The monitoring is being completed through partnerships with the U.S. Geological Survey Ohio Water Science Center, the Northeast Ohio Regional Sewer District, the U.S. EPA National Research and Monitoring Laboratory, and with additional funding from the Lake Erie Protection Fund. As well, Cuyahoga County Board of Health is providing assistance with sample collection for the duration of the sampling program. CRWP will be presenting results from the design and construction phases, and monitoring program over the next two years to CRWP Members and the larger planning, and engineering community in Northeast Ohio through selected workshops and training events.

USGS monitoring
In order to verify the effectiveness of the porous paving system in reducing runoff, the USGS has installed monitoring systems under and around the parking lot. The monitoring is being accomplished through several methods. During the pavement installation, TDR (time domain reflectometers) sensors were placed, at differing depths, within the aggregate base, to remotely measure the moisture content within the pavement base.

A second monitoring device, a flume, was installed at the outflow of the parking lot subdrainage, prior to outletting into the bio-swale. The flume will measure the quantity of drainage that exits the day-lighted subdrainage pipe, and in conjunction with a third monitoring device, a rain gauge, will record the time between a significant rainfall event, and the time it takes for the runoff to exit the pavement system. There are plans to install two more flumes as well, one at the detention basin outflow and the other at the curb cut at the end of the parking lot. In addition, the runoff collected from the flumes may be sampled for water quality.

Conclusion
The site will establish a natural and healthy environment for employees and workers through the attractive landscape plantings and the pleasant seclusion on the property. Using environmental sensitivity, the new office building develops the site in a sustainable manner. Restoring and retaining the natural systems through a design that is conscientious of natural features is key to the project vision. The porous paving system, rain garden, bio-swale and bio-detention are an integral part of the sustainable site design.

• Project: Proposed Cawrse & Associates, Inc. Office Site
• Location: Chagrin Falls, OH; Geauga County, Ohio
• Landscape Architect: Cawrse & Associates, Inc.
• Architect: Richard N. Yoe, Architect
• Civil Engineer: Hejdux-Cox & Associates, Inc.
• General Contractor: Gottschalk Building Company
• Paver Consultant: Drew Snoply, Unilock
• Landscape Contractor: John Seliga Landscaping
• Paver Contractor: JFD Landscapes
• Ohio Native Plant Consultants: Klynn Nursery, Ohio Prairie Nursery
• Landscape Lighting: Pinnacle Lighting Group
• Stormwater Consultants:
  Chagrin River Watershed Partners, Inc.: Rachel Webb, LID Coordinator
  U.S. Geological Survey: Robert A. Darner P.E., Hydrologist
• Awards: 2007 Smart Growth Association Award – Green Design - Sustainable Site Practices, presented by the Smart Growth Education Foundation

See an image gallery of the company’s low impact landscaping features.

This article was written by Richard Washington at Cawrse & Associates. It also appears in Interlocking Concrete Pavement Magazine.