Federal Highway Administration

HEC-22 Urban Drainage Design Manual

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Compare each cited field to the official PDF before relying on it. What this means

Excerpts are overview/reference material; design storm return periods include multiple contexts (minor/major systems vs. detention regulatory examples). Document full title, adoption dates, and relationship to state manuals not stated in provided chunks. HEC-22 does not mandate a single required software list—programs are cited as commonly used, not exclusively required.

Fields not found in document: document_metadata.adoption_or_effective_date, document_metadata.last_revised_date, document_metadata.relationship_to_state_manual

Other federal manuals: HDS-4 Introduction to Highway Hydraulics, HEC-14 Hydraulic Design of Energy Dissipators for Culverts and Channels, HEC-15 Design of Roadside Channels with Flexible Linings, HEC-21 Design of Bridge Deck Drainage, HEC-24 Highway Stormwater Pump Station Design

Document Metadata

Jurisdiction level

Federal

“Federal, State, and local regulations often guide the quality and quantity of the discharge.”
Section 3.1, page 47

State

Not found in document

No evidence cited

Version / edition

4th edition

“HEC-22, 4th edition Chapter 3 - System Planning”
page 47

Adoption / effective date

Not found in document

No evidence cited

Last revised date

Not found in document

No evidence cited

Relationship to state manual

Not found in document

No evidence cited

Design Criteria

Design storm return periods (years)

2-year, 10-year, 25-year, 50-year, 100-year

“The minor system is typically designed to carry runoff from an intermediate design storm event such as the 0.1 annual exceedance probability (AEP) (10-year return period) event.”
Section 3.2, page 47

Water quality volume method

First-flush / water quality volume (WQV) commonly estimated as: the first 0.5 inch of runoff from impervious area; the first 0.5 inch of runoff from the entire catchment; or the first 1.0 inch of rainfall resulting in runoff from the entire catchment; also V_WQv = Q A = (R_V P) A

“engineers estimate first flush volume as: • The first 0.5 inch of runoff of impervious area. • The first 0.5 inch of runoff of the entire catchment area. • The first 1.0 inch of rainfall resulting in runoff from the entire catchment area.”
Section 11.1, page 231

Peak flow calculation method(s)

Rational Method, Statistical analysis (log-Pearson type III), NRCS (SCS) peak flow method, USGS rural regression equations, USGS nationwide urban regression equations (three-parameter or seven-parameter), Unit hydrograph methods

“One of the most used approaches for the calculation of peak flow from small areas is the Rational Method”
Section 4.2.2, page 55

Hydrologic/hydraulic software

HEC-HMS, SWMM, WinTR-20, WinTR-55, NSS

“Application of hydrograph methods often necessitates computer programs such as the Hydrologic Engineering Center Hydrologic Modeling System (HEC-HMS), the Stormwater Management Model (SWMM), WinTR-20, WinTR-55, among others”
Section 4.3 Design Hydrographs, page 64

Approved BMP categories

detention basins, retention basins, water quality control facilities, best management practices (BMPs), infiltration trenches, infiltration basins, stormwater quantity and quality control facilities (detention or retention ponds)

“storm drainage systems often rely on detention or retention basins and other best management practices (BMPs) for the control of discharge quantity and quality.”
Section 3.1, page 47