Pervious Concrete Pavement Design for Sustainable Porous & Permeable Stormwater Drainage

A properly designed pervious concrete pavement system can reduce the environmental impact often associated with development. Pervious concrete pavement systems can also be used to improve the environmental performance of existing sites without compromising the business value of a property by replacing existing conventional pavements. The capability to simultaneously maintain water quality, reduce flooding, increase base flow, and preserve valuable parking areas for the property owner, especially in retrofit applications, are capabilities not easily obtained with other water quality or flood mitigation alternatives. Pervious concrete also provides a unique leadership opportunity for stewardship in context-sensitive construction and Low-Impact Development (LID).

Provided here is a description of the fundamental hydrologic behavior of pervious concrete pavement systems and a demonstration of the basic design methodologies appropriate for a variety of sites and circumstances. The limitations of these methodologies will also be briefly discussed.

w Abstract

w List of Acronyms & Abbreviations

w References

w Appendix A – Curve Numbers

w Appendix B – Software & Example Analysis

w Appendix C – Rainfall Information

w Appendix D – Initial Estimates

w Appendix E – Slope Effects

Part 1 – Introduction

Part 2 – Overview of Pervious Concrete Pavement System Applications

2.1 Water Quality and Water Quantity

2.2 Uses and Applications

2.2.1 Detention and Retention Structures

2.2.2 Passive or Active Mitigation Systems

2.3 Effects of Ponds

Part 3 – Hydrological Design Concepts and Issues

3.1 Runoff Characteristics

3.2 Hydrologic Characteristics of the Watershed: Infiltration and Runoff

3.3 Permeability and Storage of the Pervious Concrete Pavement System

3.3.1 Storage Capacity

3.3.2 Effects of Slope

3.3.3 Effective Storage Capacity — Recovery Through Infiltration

3.4 Design Storms

3.4.1 Selection of the Appropriate Return Period

3.4.2 Design Storm Characteristics

3.4.2.1 Duration-Depth-Frequency

3.4.2.2 Intensity-Duration-Frequency

3.5 Water Quality

Part 4– Hydrological Design Methods

4.1 Introduction

4.2 Percent Impervious Surface

4.3 The NRCS Curve Number Method

4.3.1 Curve Number Method — Design Methodology

4.3.2 Curve Number Method — Design Input

4.3.2.1 Curve Number Method — Design Storm

4.3.2.2 Curve Number Method — Definition and Values

4.3.3 Curve Number Method — Design Procedure

4.3.4 Curve Number Method — Output

4.4 The Rational Method

4.4.1 Rational Method — Design Methodology

4.4.2 Rational Method — Design Input and Use

Part 5 – Examples and Discussion

5.1 Example Proposed Development

5.1.1 Development Plan

5.1.2 Site Conditions and Constraints

5.2 Pre- and Post-Development Runoff Without Pervious Concrete

5.3 Preliminary Estimates for Use in the CN Method and Discussion

5.3.1 Initial Estimates of Infiltration Rate

5.3.2 Initial Estimates of the CN of Adjacent Areas

5.4 Results and Discussion of Site Analysis Including Pervious Concrete

5.4.1 Runoff and Equivalent Curve Numbers

5.4.2 Discussion of Findings of Site Analysis

5.4.2.1 Infiltration Effects

5.4.2.1.1 System Recovery Time

5.4.2.1.2 Comments of Performance with Silty Soils

5.4.2.2 Equivalent Curve Number

5.4.3 Other Design Considerations

5.4.3.1 Comments on the Use of Stone Base

5.4.3.2 Alternate Performance Specifications

5.4.3.3 Additional Impervious Surfaces

5.4.3.4 Comments on Using Pervious Concrete Systems in Sandy Regions

5.4.3.5 Calculations for Passive Mitigation Applications

5.4.3.6 Analysis with a High Water Table

5.5 Estimation of Peak Discharge

5.6 Comments on Designing a Robust Solution

5.6.1 Sensitivity Analysis

5.6.2 Discussion of Sensitivity Analysis Results

5.6.3 Recommendations

5.7 Design Factors in Cold Climates

5.7.1 Frost Heave

5.7.2 Storage Capacity in Cold Climates

5.8 Comments on the Rational Method

WARNING: Contact with wet (unhardened) concrete, mortar, cement, or cement mixtures can cause SKIN IRRITATION, SEVERE CHEMICAL BURNS (THIRD DEGREE), or SERIOUS EYE DAMAGE. Frequent exposure may be associated with irritant and/or allergic contact dermatitis. Wear water-proof gloves, a long-sleeved shirt, full-length trousers, and proper eye protection when working with these materials. If you have to stand in wet concrete, use waterproof boots that are high enough to keep concrete from flowing into them. Wash wet concrete, mortar, cement, or cement mixtures from your skin immediately. Flush eyes with clean water immediately after contact. Indirect contact through clothing can be as serious as direct contact, so promptly rinse out wet concrete, mortar, cement, or cement mixtures from clothing. Seek immediate medical attention if you have persistent or severe discomfort.