====================================================================== Building Drainage & Stormwater Management Quick Reference Guide ====================================================================== DEFINITION ---------------------------------------- The Building Drainage & Stormwater Management Quick Reference Guide is a concise, practitioner-oriented technical resource that synthesizes design criteria, regulatory requirements, and best practices for managing on-site rainwater runoff and wastewater conveyance in built environments. It supports engineers, architects, planners, and contractors in selecting, sizing, and integrating drainage infrastructure to ensure public safety, environmental protection, and regulatory compliance. The guide emphasizes performance-based solutions—including green infrastructure, hydraulic calculations, and code-aligned detailing—for both new construction and retrofit projects. OVERVIEW ---------------------------------------- Building drainage encompasses the controlled removal of wastewater (sanitary and greywater) and stormwater from roofs, paved surfaces, and landscaped areas via piping systems, channels, and retention/detention features. Stormwater management specifically addresses the hydrologic and hydraulic challenges posed by impervious surfaces—such as increased runoff volume, peak flow rates, and pollutant loading—by applying principles of water balance, time-of-concentration analysis, and low-impact development (LID). Core design standards draw from national and local codes (e.g., IPC, UPC, ASCE 24, EPA SWMM guidance) and integrate climate-resilient considerations like intensified rainfall intensities due to climate change. Practical implementation requires coordinated integration across disciplines: civil engineering (hydraulic modeling, pipe sizing), landscape architecture (bioswales, rain gardens), and building services (roof scuppers, downspout routing). Performance verification often relies on tools such as TR-55, Rational Method calculations, and continuous simulation models (e.g., SWMM) to validate compliance with municipal MS4 permits, watershed-level TMDLs, and green building certifications (e.g., LEED v4.1 SSc6, Green Globes Stormwater Management). KEY COMPONENTS ---------------------------------------- 1. Roof Drainage Systems 2. Storm Sewer Networks 3. Best Management Practices (BMPs) / Low-Impact Development (LID) Features APPLICATIONS ---------------------------------------- - Sizing roof leaders and catch basins for design storms - Designing site-level detention/retention basins to meet municipal runoff rate and volume control requirements - Integrating permeable pavements, rain gardens, and green roofs into site development plans KEY FORMULAS ---------------------------------------- Rational Method: Q = C × i × A -> Calculates peak runoff rate (Q) in cfs, where C is the runoff coefficient, i is rainfall intensity (in/hr) for a given duration and return period, and A is the drainage area (acres) Manning’s Equation (Open Channel Flow): V = (1.49/n) × R^(2/3) × S^(1/2) -> Determines average flow velocity (V) in ft/s for open channels or pipes flowing partially full; n = Manning’s roughness coefficient, R = hydraulic radius (ft), S = slope of energy grade line Time of Concentration (Kirpich Equation): t_c = 0.0195 × L^0.77 × S^(-0.385) -> Estimates time of concentration (t_c) in minutes for overland flow on unpaved surfaces, where L = flow length (ft) and S = slope (ft/ft) RELATED CONCEPTS ---------------------------------------- - Hydrologic Modeling - Green Infrastructure - Municipal Separate Storm Sewer Systems (MS4) REFERENCES ---------------------------------------- ASCE 24-14: Flood Resistant Design and Construction (https://www.asce.org/standards/asce-24-14-flood-resistant-design-and-construction/) EPA National Menu of Best Management Practices (BMPs) (https://www.epa.gov/npdes/stormwater-menu-best-management-practices-bmps) International Plumbing Code (IPC) 2021 Edition (https://codes.iccsafe.org/content/IPC2021) TAGS ---------------------------------------- stormwater, building_codes, hydraulic_design, low_impact_development, drainage_engineering