Urban Stormwater Systems Design, Installation, Operation, and Maintenance Standards

ASCE/EWRI 45-05, ASCE/EWRI 46-05, ASCE/EWRI 47-05: Urban Stormwater Systems Design, Installation, Operation, and Maintenance Standards

Effective urban stormwater management is critical for public safety, environmental protection, and resilient infrastructure. For engineering professionals tasked with designing, building, and maintaining these vital systems, adherence to industry-leading standards is paramount. The comprehensive suite of ASCE/EWRI 45-05, ASCE/EWRI 46-05, and ASCE/EWRI 47-05 provides the essential guidelines necessary to achieve these objectives.

What is ASCE/EWRI 45-05, ASCE/EWRI 46-05, ASCE/EWRI 47-05?

This tripartite standard, developed by the Environmental and Water Resources Institute (EWRI) of the American Society of Civil Engineers (ASCE), establishes industry-leading practices for urban stormwater systems. It is comprised of three distinct, yet complementary, documents: ASCE/EWRI 45-05 for design, ASCE/EWRI 46-05 for installation, and ASCE/EWRI 47-05 for operation and maintenance. Together, they offer a cohesive framework for ensuring the performance, longevity, and safety of urban drainage infrastructure.

Scope & Purpose

These standards govern the full lifecycle of urban stormwater management systems, from initial conceptualization through ongoing operational upkeep. Specifically, they detail requirements for site analysis, hydrological calculations, the selection of materials, construction methodologies, and routine maintenance procedures. While focusing on the design, installation, and operational aspects of urban stormwater systems, the standards do not typically extend to the design of wastewater collection systems or the broader regulatory frameworks governing water quality discharge permits, though they provide a foundation for compliance.

Who Must Comply?

• • Primary audience: Civil Engineers, Environmental Engineers, Urban Planners, Project Managers, Construction Managers, and Public Works Officials.
• • Industries affected: Civil Engineering, Water Management, Municipal Services, Urban Development, and Construction.
• • Compliance nature: While not always legally mandatory, compliance is highly recommended and often a de facto requirement for project approval, funding, and to mitigate liability.
• • Enforcement: Compliance is typically overseen by municipal review boards, permitting agencies, and through contractual obligations in project specifications.

Key Requirements Overview

The ASCE/EWRI 45-05, 46-05, and 47-05 standards collectively mandate a rigorous approach to urban stormwater management. Key provisions include:

• • Thorough Site Analysis: Professionals must conduct comprehensive evaluations of topography, geology, soil conditions, and existing infrastructure to inform design decisions.
• • Accurate Hydrological Modeling: The standards require precise determination of runoff quantities and qualities, considering appropriate design storms and return periods for safe capacity.
• • Quality-Driven Material Selection: Selection of durable and appropriate materials for conveyance structures, inlets, outlets, and appurtenances is emphasized.
• • Best Practices in Installation: Proven construction techniques are detailed to ensure system integrity, proper alignment, and effective jointing to prevent infiltration and exfiltration.
• • **Proactive Operation and Maintenance