Permeable Paver Stormwater Management: How Ursinus College Built a Sustainable Multi-Use Space

Stormwater management is one of the most pressing challenges in modern construction, particularly on campuses and urban sites where impervious surfaces contribute to flooding and watershed degradation. When Ursinus College in Collegeville, Pennsylvania, set out to build a new Student Commons in 2020, designers faced the dual challenge of creating a versatile community space while minimizing runoff into nearby Perkiomen Creek. Their solution was a Permeable Interlocking Concrete Pavers Performance Durability and Stormwater system from Belgard that serves both as a structural roadway and a green stormwater infrastructure asset. This case study offers builders valuable insights into permeable paver design, installation, and long-term performance.

Understanding Permeable Interlocking Concrete Pavement Systems

Permeable interlocking concrete pavement (PICP) systems are engineered paving surfaces that allow rainwater to infiltrate through the pavement layer into an underlying stone base, where it is temporarily stored and gradually released into the subgrade or conveyed to the storm sewer system. Unlike traditional impervious asphalt or concrete, PICPs function as both a load-bearing traffic surface and a stormwater management tool.

How Permeable Pavers Work

The system relies on several key components working together:

• Concrete pavers: Specially designed units with small joints (typically 1/8 to 1/2 inch wide) that allow water to pass between them rather than running off the surface.
• Joint aggregate: Clean, angular stone chips that fill the spaces between pavers, providing both structural interlock and permeability.
• Open-graded base and subbase: Layers of crushed stone with minimal fines, creating void space (typically 30-40 percent) for stormwater storage.
• Geotextile fabric: A filter layer placed between the subbase and the native soil to prevent migration of fine soil particles into the aggregate layers.
• Underdrain system: Perforated pipes within the subbase that collect and convey excess water to the storm sewer system when the storage capacity is exceeded.

This layered approach allows permeable pavements to manage everything from routine rainfall to significant storm events while supporting vehicular loads comparable to conventional pavement.

Key Benefits for Builders and Site Developers

For contractors and developers weighing permeable pavement options, several advantages distinguish PICP systems from alternative stormwater solutions:

1. Reduced stormwater infrastructure: Less need for traditional curb-and-gutter systems, catch basins, and underground detention tanks, lowering overall site development costs.
2. Space efficiency: Pavement serves double duty as both a traffic surface and a stormwater management facility, eliminating the need for separate detention ponds or rain gardens.
3. Groundwater recharge: Infiltration helps replenish local aquifers and maintain base flow in nearby streams and creeks.
4. Heat island mitigation: Lighter-colored concrete pavers reflect more solar radiation than dark asphalt, reducing ambient temperatures around buildings and paved areas.
5. Durability: High-quality concrete pavers like Belgard Aqua Roc II are rated for vehicular traffic and can withstand freeze-thaw cycles better than poured concrete surfaces.
6. Aesthetic versatility: Pavers come in a wide range of colors, patterns, and textures that can complement architectural themes and campus branding.

The Ursinus College Student Commons: A Case Study in Sustainable Design

Project Background and Design Objectives

The Ursinus College Student Commons was designed by architectural firm Bernardon with two primary goals: preserve and integrate a historic house at the intersection of the college and Collegeville town, and create a multi-functional building serving both campus and community needs. The new facility houses Admissions offices, a publicly accessible bookstore and cafe, study lounges for students, and a multi-purpose room available to the broader community.

From a stormwater perspective, the site presented a significant challenge. The existing stormwater collection system on campus ultimately discharges into Perkiomen Creek, which has experienced severe flooding over the last decade due to increased impervious land coverage in the growing suburban area around Collegeville. It was critical that the Student Commons be designed to limit any increased runoff and minimize local flooding.

Why Permeable Pavement Was Selected

The existing road serving the building site was a standard two-way asphalt drive. The design team envisioned transforming this space into a new type of roadway that could easily double as an outdoor plaza and event space. In addition to regular vehicular traffic, they imagined food trucks serving there during community-wide festivities. Permeable pavement emerged as the ideal solution because it met both structural and environmental requirements simultaneously. It could support vehicular loads while functioning as a green infrastructure system for managing stormwater runoff.

The team selected Belgard Aqua Roc II in the 4×8 mechanical Herringbone pattern with 80 mm thickness. The paver color blend of Sable with Charcoal and Linen accents complemented the existing brick buildings on campus and the official Ursinas red color, ensuring the new pavement harmonized with the campus aesthetic.

As the designer noted, Belgard is the number one go-to in concrete paver products, and the installer was already familiar and happy with the product line. The pavers were described as attractive, durable, and well-rated for product quality from a vehicle capacity standpoint.

Engineering the Permeable Paver System

Cross-Section Design and Aggregate Layers

Belgard Stormwater Engineer Paul Cureton, P.E., collaborated with civil engineers Woodrow and Associates Inc. to design the permeable pavement system. Cureton provided critical input on aggregate depth requirements, drive lane slope considerations, and underdrain connections to the existing storm sewer system.

The designed cross-section for the approximately 20,000 square foot permeable pavement system included:

This engineered section provided substantial void space within the aggregate layers for temporary stormwater storage while distributing vehicular loads across the subgrade.

Drainage and Flow Control

Several engineering features were incorporated to manage water flow effectively:

• Underdrain system: A perforated pipe network within the subbase layer collects infiltrated water and conveys it to the existing storm sewer system.
• Outlet control structure: An adjustable control structure regulates the release rate of stormwater from the permeable pavement system, ensuring downstream systems are not overwhelmed.
• Flow dams: Two flow dams were installed along the 300-foot-long drive lane to maximize vertical infiltration into the sloping subgrade. These barriers force water to infiltrate vertically rather than migrating along the slope within the aggregate layer.
• Slope management: The 2-degree sloping subgrade required careful design to ensure even distribution of infiltrated stormwater and prevent preferential flow paths.

These elements worked together to create a system that not only manages stormwater volume but also controls its release timing, a critical factor in mitigating downstream flooding. For builders working on similar projects, understanding Construction Site Environmental Management and Erosion Control Best practices is essential for protecting watersheds during and after construction.

Lessons for Builders and Future Applications

Additional Sustainable Features at the Student Commons

The permeable pavement system was one component of a broader sustainability strategy for the Student Commons. Other green features included:

• All-LED lighting throughout the building and site
• Outdoor furniture constructed from recycled materials
• Intentional, free-flowing natural landscaping that reduces irrigation needs
• Preservation and adaptive reuse of the historic house on the site

This integrated approach demonstrates how sustainable stormwater solutions can complement broader green building strategies. Builders looking to incorporate similar approaches should explore Stormwater Management for Builders Using the Epa Stormwater Calculator as a planning tool during the design phase.

Key Considerations for Future Permeable Paver Projects

The Ursinus College project offers several takeaways for builders and contractors considering permeable pavement systems for their own projects:

1. Engage a stormwater engineer early. Belgard provided their in-house engineer to collaborate with the civil engineering team, ensuring the system was optimized for site-specific conditions including slope, soil type, and drainage requirements.
2. Consider dual-use design from the start. The roadway that doubles as an event plaza was conceived early in the design process, making it easier to integrate the structural and aesthetic requirements of a permeable pavement system.
3. Select pavers with proven load ratings. The 80 mm Aqua Roc II pavers were specifically chosen for their vehicular load capacity, a critical specification for any permeable pavement that will carry traffic.
4. Design for the watershed, not just the site. The project was motivated by the need to protect Perkiomen Creek and reduce regional flooding, which drove the decision to infiltrate stormwater on site rather than simply convey it away.
5. Coordinate with experienced installers. The contractor selected was already familiar with Belgard products, reducing the learning curve and ensuring proper installation techniques.

Steve Gehringer, director of facilities for Ursinus College, noted that this was their first experience with Belgard and that they found it to be a really good product. The college plans to continue using Aqua Roc II as a permeable solution on future projects as opportunities arise.

The Role of Permeable Pavement in Broader Stormwater Management

Permeable interlocking concrete pavement systems like the one at Ursinus College represent an important tool in the builder stormwater management toolkit. They offer a way to meet increasingly stringent environmental regulations while creating more usable, attractive outdoor spaces. When properly designed and installed, these systems can handle decades of vehicular traffic while managing stormwater from even significant rain events.

For builders who want to deepen their understanding of stormwater compliance and planning, reviewing Stormwater Management fundamentals provides a solid foundation for integrating permeable pavement into broader site development strategies.

With the installation of Belgard permeable pavers, Ursinus College achieved its goal of creating a sustainable green infrastructure with minimal impact on the watershed. The Student Commons now successfully serves both the campus and the local Collegeville community, demonstrating that smart stormwater design and beautiful, functional outdoor spaces are not competing priorities but complementary ones.