Case Study 1: Paseo Verde

  • Landscaped rain gardens at the front entrance of Paseo Verde. Image Credit: Urban Land Institute

Project Overview   |   Design Summary   |   Keys to Success   |   Decision-Making    |   Challenges   |   Maintenance 


Development Type: Urban Infill
Location: 1900-1950 North 9th Street, Philadelphia, PA 19122
Developer/Design Team: Asociación Puertorriqueños en Marcha (APM); Jonathan Rose Comapanies, WRT, LLC – Architect & Landscape Architect; Urban Engineers, Inc.
Sewer Type: Combined Sewer
Completion Date: August 2013


Project Overview: 

Paseo Verde is a mixed use/mixed income development on an urban infill site in the ethnically diverse, low-income neighborhood of North Philadelphia, Pennsylvania. The development consists of 67 units of market rental housing, 53 units of LIHTC affordable rental housing, and 30,000 square foot of commercial space that houses a Federally Qualified Health Center, pharmacy, and APM’s headquarters and program offices. The project was built by a partnership between an established community development corporation and an experienced developer committed to affordability and sustainability. Paseo Verde achieved three Leadership in Energy and Environmental Design (LEED) Platinum certifications and incorporated extensive green infrastructure practices to demonstrate compliance with local stormwater management requirements and create an attractive development project that achieved full occupancy in less than one year. The Asociación Puertorriqueños en Marcha (Association of Puerto Ricans on the March, or APM), one of Philadelphia’s most prolific community development corporations, along with Jonathan Rose Companies, orchestrated the development.

The property had been a city-owned parking lot leased to the local gas utility for decades. It was desolate and unwelcoming, described as an “open wound” in the neighborhood. The 1.9-acre site sits less than two miles north of Center City Philadelphia in a densely populated and highly impervious area. The site is immediately adjacent to Temple University and has direct access to a regional rail system, several bus lines and the Broad Street subway.

Paseo Verde was realized through a close collaboration between the APM community organization with deep roots in its neighborhood, the Jonathan Rose Companies developer with a deep commitment to meeting the highest standards of triple-bottom-line (social, environmental, and financial) sustainability, many designers committed to integrating a green building into a green neighborhood, and public officials who saw the perfect symbol for a resurgent, forward-thinking city. Above it all, this remarkable transformation was built for an enviably low price, using strictly off-the-shelf technologies.


Design Summary

The design team incorporated high performance green features that required additional planning but no additional construction costs. The green approach helped to avoid costly delays in getting local approvals since the green stormwater management program met regulators’ expectations. The stormwater management approach includes the capture of 3 inches of stormwater managed through the use of blue roofs (37,600 SF), green roofs (15,600 SF), rain gardens (4,000 SF), and porous paving (80 SF). Stormwater from the blue roofs, green roofs, and rain gardens is sent to subsurface infiltration basins and overflow is discharged back to the city sewer system.

  • Blue roofs (actually white) atop Paseo Verde North and South’s apartments collect water during storms of up to a 100-year return interval, and then slowly release it afterwards. The blue roofs are equipped with standard waterproofing and include outlet control devices on the roofdrains. The blue roofs were sized to store up to 3 inches of stormwater for up to 72 hours and can hold up to 3 feet of snow (the equivalent of 3 inches of ponded water) to meet code requirements. The construction means and methods to add additional structural strength were the same as those for conventional roofs, therefore, no additional cost was incurred. This was accomplished using a typical roof design that includes open web wood trusses and Batt insulation, plywood sheathing, 2 inches of rigid insulation, and a TPO (thermoplastic polyolefin) waterproofing membrane.
  • Green roofs were placed above a podium structure so no additional support was required. The green roof system includes 4 inches of growing media and prefabricated green roof trays that were delivered to the site with mature, drought tolerant sedum plants. Large tree planters were placed directly above load bearing supporting columns.
  • Rain gardens include infiltration soil media with a variety of native plantings (grasses, perennials, and trees) – roughly 25 to 30 different species.
  • Subsurface infiltration basins provide additional stormwater storage capacity beyond what is provided in the blue roofs, green roofs, and rain gardens and consist of perforated HDPE pipe surrounded with varying sizes of stone and a geotextile fabric.
  • Porous pavement design includes Hanover concrete blocks with gravel in between. Stormwater passes through the gravel and infiltrates into the soil below.

Keys to Success: 

  • Working within the Regulatory Framework: By incorporating green infrastructure in the development, Paseo Verde helps the City of Philaelphia meet its regulatory obligations under the Clean Water Act by minimizing stormwater runoff and improving water quality. Meeting these obligations within a combined sewer area also helps the City reduce stormwater management and wastewater treatment costs. Sustainable developments like Paseo Verde can be instrumental to marketing the City as a forward thinking, green destination.
  • Economic Uplift: The Paseo Verde development shows that smart design can be accessible to everyone. The green infrastructure components have helped to create a healthy and respectful environment within the community – less crime, less noise and no graffiti. As a result, it took less than 1 year to achieve full occupancy after opening, revitalizing the local area.
  • Triple Bottom Line: The decision to incorporate green infrastructure into the project was made to expedite permitting, reduce cost, and provide an amenity to make the Charlotte Wilson Complex a highly desirable housing option.

Decision-Making

The project team consisting of APM, Jonathan Rose Companies, and WRT did not need to incorporate green infrastructure into the design to the extent they did. For example, including nearly 16,000 square feet of green roof into the design was not specifically required in order to meet the local stormwater management requirements, but other measures would have been necessary if not a green roof. The small rain gardens and the porous pavement were not required either. The project development team elected to include accessible green roofs and the rain gardens for the residents. The visually appealing features function as a usable amenity for the residents, while adding stormwater management benefits. The pervious pavement was included to “disconnect” more impervious area and promote additional groundwater recharge. The stormwater management requirements could have been met using a more robust subsurface infiltration system. That approach would have left the residents without a rooftop amenity and would not have provided the community with the added environmental and aesthetic benefits that come with the surface green components.

  • Blue roofs were chosen as a cost-effective way to manage stormwater without the need for additional infrastructure. The cost and price points for construction had to be reasonable for affordable housing. To achieve these dual—and sometimes competing—goals, the project development team looked for efficiencies in every green design element it pursued and chose features that would simultaneously provide multiple benefits. For example, green roofs were selected as a way to reduce the amount of impervious cover on the site while also providing an amenity for the residents. By using a podium design approach for the supporting structure, no additional construction costs were incurred, which helped justify the decision to install green roofs.
  • Many of the building’s sustainability measures were selected to meet multiple objectives that include adding amenities to help market the building and provide stormwater management to meet local regulations. The building’s green infrastructure not only manages stormwater in accordance with local requirements but also adds visual appeal.
  • The design supports the city of Philadelphia’s nationally recognized stormwater management strategy, which processes stormwater through green infrastructure rather than through pipes, and helps tie the site into a neighborhood known for its tree-lined streets. The project development team wanted the project to blend in with the surrounding community. Neighboring developments have helped to enliven and green the sidewalks.
  • The project development team worked closely with regulators during the planning stages to come up with a collaborative solution to stormwater management that met the goals of all parties. A common goal was to incorporate visible, surface green infrastructure components. Neither the project development team nor the city representatives wanted to build a large underground detention basin. Blue roofs, green roofs, rain gardens, and porous paving all provided above-ground, cost-effective, and visible stormwater management solutions.
  • Green spaces were envisioned from the beginning during concept design, and stormwater management was integrated later in the design process. The decision to include rain gardens and porous pavement was driven by stormwater management requirements. Blue roofs and green roofs alone could not provide enough stormwater storage volume to meet the requirements, so the project development team decided to convert planned landscaped areas into rain gardens and install pervious pavement in a small sidewalk area. Designers viewed this as a way to combine stormwater management with aesthetic improvements.

 


Challenges:

Paseo Verde has taught the development team a lot about design and stormwater management. The developers were glad they had made LEED certification and green design a top priority from the very beginning. In the case of Paseo Verde, that meant pursuing low-cost green features and achieving sustainability through multiple efficiencies.

In order to meet stormwater management requirements, a large quantity of stormwater had to be captured. To overcome this challenge, the project development team used innovative green stormwater infrastructure to demonstrate compliance, which also provided environmental and aesthetic benefits for the developers, the residents and the community.

It is very difficult to separate the cost of green infrastructure facilities that are incorporated into a larger development project. In the case of Paseo Verde it is particularly difficult because there was no extra cost. The stormwater management cost is primarily attributed to the subsurface infiltration basins and amounts to approximately $134,000. This could have been twice as much had the development team elected not to incorporate green infrastructure. Below is a cost breakdown of the green infrastructure elements of the project:

  • Blue roof – No additional cost to the traditional roofing system was required. Custom PVC roof drains that extend 3 inches above the roof deck and that included drilled perforations added a negligible cost. No additional insurance was required.
  • Green roof – The design included a podium roof deck and tree planters strategically placed above supporting columns, which did not incur additional structural reinforcement cost. The cost to install the vegetated tray systems and trees was part of the overall project landscaping cost of approximately $42,000.
  • Rain gardens – The rain gardens were incorporated into areas that were already planned as landscaped areas so there was no extra cost beyond the total landscaping cost of $42,000.
  • Pervious concrete pavers – The pervious concrete paver element was a very small component of the project and was completed by the main concrete contractor. The cost for the porous pavement was included in the overall concrete cost for the project.

Maintenance Overview: 

  • APM maintains the green infrastructure at Paseo Verde, which takes the responsibility away from the residents.
  • Maintenance for the blue roofs is minimal and includes regular inspections to ensure the roof drains are not clogged and are functioning properly. Since maintenance is needed for a conventional roof, there is no additional maintenance cost associated with the blue roofs.
  • The building management company currently maintains the green roofs and the rain gardens in-house and does not rely on specialty contractors. Maintenance activities include traditional landscaping services such as weeding, plant replacement, and initial establishment-phase watering. Now that the trees, native species, and sedums are fully established, no regular watering is required. The cost to maintain the green roofs and rain gardensis no higher than traditional landscaping. In fact, the maintenance cost is reduced by installing native, hardy species that don’t require regular watering. Regular lawn mowing services are not required either.
  • The only maintenance required for the porous pavement is to keep the gravel area free and clear of debris. This is done as part of the normal housekeeping activities so no additional cost is required.

* Paseo Verde is located in Philadelphia and reflects that city’s regulations and incentives. Cities and towns across the nation are finding ways to encourage and facilitate the use of green infrastructure. Developers are responding with innovative, high-value projects.

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