Thomas H. Cahill 
Low Impact Development and Sustainable Stormwater Management 

Sustainable Stormwater Management introduces engineers and designers to ideas and methods for managing stormwater in a more ecologically sustainable fashion. It provides detailed information on the design process, engineering details and calculations, and construction concerns. Concepts are illustrated with real-world examples, complete with photographs. This guide integrates the perspectives of landscape architects, planners, and scientists for a multi-disciplinary approach. This is an enlightening reference for professionals working in stormwater management, from engineers and designers to developers to regulators, and a great text for college courses.

Table of Content

Prologue: Habitat, Sustainability, and Stormwater Managementxi

Acknowledgments xiii

1 Rainwater as the Resource 1
1.1 The Water Balance as a Guide for Sustainable Design 1
1.2 The Water Balance by Region 7
1.3 Arid Environments: The Southern California Model 11
1.4 The Altered Water Balance and Hydrologic Impacts 16
1.5 The Impacts of Development on the Hydrologic Cycle 24
1.6 The Historic Approach: Detention System Design 27
1.7 Stormwater Volume Methodologies 30

2 Stormwater Hydrology and Quality 33
2.1 Overland Flow: The Beginning of Runoff 33
2.2 Regional Hydrology 35
2.3 Stormwater Volume 39
2.4 The Water Quality Impacts of Land Development 40
2.5 The Chemistry of Urban Runoff Pollution 44
2.6 Understanding Pollutant Transport in Stormwater 47

3 Land as the Resource 51
3.1 Historic Patterns of Land Development 51
3.2 Sustainable Site Design 58
3.3 Watershed Setting and Physical Context 58
3.4 Smart Growth Issues 59
3.5 Conflict Between Desired Land Use and Sustainability 61
3.6 Physical Determinants of Land Development 62
3.7 Urban Communities with Combined Sewer Overflows 68
3.8 The Living Building and Zero Net Water Use 74

4 The Planning Process for LID 79
4.1 Sustainable Site Planning Process with Stormwater Management79
4.2 Overview of the Site Design Process for LID 86

5 The Legal Basis for LID: Regulatory Standards and LIDDesign Criteria 95
5.1 The Land-Water Legal Process 95
5.2 The Evolution of Land Development Regulation 98
5.3 The Regulatory Framework 100
5.4 Stormwater Management Regulations 105

6 LID Design Calculations and Methodology 113
6.1 Introduction to Stormwater Methodologies 113
6.2 Existing Methodologies for Runoff Volume Calculations 114
6.3 Existing Methodologies for Peak-Rate/Hydrograph Estimates120
6.4 Computer Models 121
6.5 Precipitation Data for Stormwater Calculations 123
6.6 Accounting for the Benefits of LID: Linking Volume and Peak Rate 124
6.7 Recommended LID Stormwater Calculation Methodology 124
6.8 Nonstructural BMP Credits 127

7 Design of LID Systems 131
7.1 Nonstructural Measures 131
7.2 Structural Measures 133
7.3 Pervious Pavement with an Infiltration or Storage Bed 134
7.4 Bioremediation 145
7.5 Vegetated Roof Systems 152
7.6 Capture-Reuse 158

8 Structural Measures: Construction, Operation, and Maintenance 169
8.1 Porous Pavement Systems 169
8.2 Bioremediation Systems 179
8.3 Capture-Reuse Systems 188

Appendix A: The Stormwater Calculation Process 193

Appendix B: Case Studies 213
B.1 The Transition from Research to Practice 213
B.2 Manuals 215
B.3 LID Manual for Michigan (2008) 219
B.4 Models and Watershed Studies 237
B.5 Design and Construction Projects 251

Index 283

About the author

THOMAS H. CAHILL is the Principal Environmental Engineer and President of Cahill Associates. He has over forty-two years of professional experience in water resources engineering, hydrology, hydraulics, natural resource planning, and environmental engineering, including over thirty years in private practice. Mr. Cahill is the author of over 100 technical papers and publications on land use, stormwater management, and water quality, and is a frequent lecturer at environmental and engineering conferences.