Salt Lake City

Salt Lake City Municipal Separate Storm Sewer System (MS4) Storm Water Management Plan

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This extraction needs human review.

Program plan (MS4 SWMP), not a full drainage design manual. Design criteria summarized from post-construction program text and references to the separate SLC Building Process & Design Manual / DWQ LID guide; numeric 80th-percentile rainfall depth and full BMP design specs live in those companion documents.

Fields not found in document: design_criteria.required_hydrologic_hydraulic_software, design_criteria.design_storm_return_periods_years (only 100-year detention criterion stated; 80th percentile is a percentile storm, not a return-period year)

Other manuals in Utah: City of South Salt Lake

Document Metadata

Jurisdiction level

municipality

“Permit for Discharge from Salt Lake City's Separate Storm Sewer System (MS4) Permit Number UTS000002”
Introduction

State

Utah

“Utah Pollutant Discharge Elimination System (UPDES) Permit... Utah Department of Environmental Quality (DEQ), Division of Water Quality (DWQ)”
Section 1.0

Version / edition

December 2021, Version 2024.1

“December 2021, Version 2024.1”
Cover, Page 1

Adoption / effective date

2021-12

“December 2021, Version 2024.1”
Cover, Page 1

Last revised date

2024

“Version 2024.1”
Cover, Page 1

Relationship to state manual

independent

“The City's Storm Water Management Plan (SWMP) was developed to comply with the 2021 Municipal Separate Storm Sewer System (MS4) Utah Pollutant Discharge Elimination System (UPDES) Permit”
Section 1.0

Design Criteria

Design storm return periods (years)

100-year

“Salt Lake City requires all commercial, industrial, and residential developments with impervious areas greater than 15,000 square feet to provide onsite detention facilities to limit the discharge to a pre-development rate of 0.2 cubic feet per second per acre during the 100-year storm.”
SWMP Summary / Section 7.1.2

Water quality volume method

Retain on site less than or equal to the 80th percentile storm event (or predevelopment hydrologic condition, whichever is less) for new development ≥1 acre (or common plan ≥1 acre). Redevelopment that increases impervious area by more than 10% must retain the net increase in volume for events ≤ the 80th percentile storm. Detention: limit discharge to 0.2 cfs/acre during the 100-year storm for sites with >15,000 sq ft impervious.

“requiring new and redevelopment sites greater than 1-acre (or part of a common plan of development collectively disturbing greater than or equal to 1-acre) to retain less than or equal to the 80th Percentile storm event, or a predevelopment hydrologic condition, whichever is less.”
SWMP Summary, Pages 11–12

Peak flow calculation method(s)

Rational Method (projects <1 acre), SCS Curve Number method (projects ≥1 acre)

“The SLC Design and Process Manual provides specific hydrologic methods (Rational Method for <1-acre projects and SCS Curve Number for all others) for calculating runoff volumes, and for determining the 80th Percentile Storm depth and associated water quality volume.”
Section 7.1.2, Page 51

Required hydrologic/hydraulic software

Not found in document

No evidence cited

Approved BMP categories

On-site Detention Facilities, Retention / Volume Reduction, Low Impact Development (LID), Green Infrastructure (GI), Structural Water Quality BMPs, Construction Site Erosion and Sediment Controls, Pollution Prevention / Good Housekeeping SOPs

“Salt Lake City will implement requirements for structural BMPs for on-site detention, retention, and water quality improvement, where applicable... The City requires the evaluation and inclusion of GI or LID control BMPs to meet these goals, where feasible.”
Section 7.1.2, Pages 50–51