City of Houston

Infrastructure Design Manual Chapter 9 Stormwater Design and Water Quality Requirements

CityTexashighNo

Other manuals in Texas: City of Austin, Texas Commission on Environmental Quality

Document Metadata

Jurisdiction level

municipality

“Drainage criteria administered by the City of Houston and complemented by Harris County and the Harris County Flood Control District (HCFCD)”
Section 1, 9.1.02.A, Page 9-2

State

Texas

“Infiltration report of soil testing, signed and sealed by a Professional Engineer licensed in the State of Texas”
Section 1, 9.1.04.O, Page 9-7

Version / edition

07-01-2022

“07-01-2022”
Page footer throughout (e.g., Page 9-0)

Adoption / effective date

2022-07-01

“07-01-2022”
Page footer throughout (e.g., Page 9-0)

Last revised date

2022-07-01

“07-01-2022”
Page footer throughout (e.g., Page 9-0)

Relationship to state manual

independent

“Drainage criteria administered by the City of Houston and complemented by Harris County and the Harris County Flood Control District (HCFCD)”
Section 1, 9.1.02.A, Page 9-2

Design Criteria

Design storm return periods (years)

2-year, 5-year, 10-year, 25-year, 50-year, 100-year, 500-year

“Table 9.1 – Rainfall Intensity Coefficients ... 2-year ... 5-year ... 10-year ... 25-year ... 50-year ... 100-year ... 500-year”
Section 2A, Table 9.1, Page 9-11

Water quality volume method

At a minimum, permanent stormwater quality BMPs for new development and significant redevelopment must treat the first 1/2 inch of runoff (except as noted in the Stormwater Quality Guidance Manual or Minimum Design Criteria); LID features may also store/treat a water quality volume (WQv).

“At a minimum, the system must be designed to treat the first 1/2 inch of runoff, except as noted in the SWQGM or the MDC.”
Section 9, 9.9.01.C.3, Page 9-46

Peak flow calculation method(s)

Rational Method (drainage areas up to 200 acres; storm sewer projects up to 640 acres), HCFCD H&H Manual methodology (areas greater than 640 acres), Clark Unit Hydrograph Method (dynamic hydrograph modeling), NRCS Dimensionless Unit Hydrograph (detention volume / static conditions), Malcolm's Small Watershed Method (detention volume / static conditions)

“Rational Method: The Rational Method will be used to estimate peak flows for individual drainage areas up to 200 acres in size, and for project areas up to 640 acres in size.”
Section 2A, 9.2.01.B.2.a, Page 9-12

Required hydrologic/hydraulic software

HouStorm

“HouStorm shall be used to perform 2-year and inlet design analysis and design of storm drainage systems”
Section 2A, 9.2.01.A, Page 9-10

Approved BMP categories

Bioretention, Infiltration Trenches, Porous Pavement / Porous Paver Systems, Vegetated Swales (dry and wet), Green Roof, Hard Roof, Rain Barrels, Detention ponds / stormwater detention basins

“Low Impact Development (LID) techniques that are considered acceptable for achieving detention are Bioretention, Infiltration Trenches, Porous Pavement, Vegetative Swales, Green Roof, Hard Roof, and Rain Barrels.”
Section 2A, 9.2.01.H.3.j, Page 9-31