how to build protection for mother nature into your project

2 0 0 9 G U I D E F O R D E V E L O P E R S & D E S I G N E R S

Standard Urban Stormwater Mitigation Plans (SUSMP)

Site-Specific Mitigation Plans

City of Los Angeles

Department of Public Works

Bureau of Sanitation

Watershed Protection Division

HOW TO BUILD

PROTECTION FOR MOTHER NATUREINTO YOUR PROJECT


This handbook will give you many ideas for features you can

design and build into your projects to control stormwater

runoff that could otherwise pollute Los Angeles’ waterways.

These features include vegetated filter strips, porous pavement,

flow-through planters, parking lot tree wells, infiltration

swales, and rooftop water capture systems. From rooftops

to sidewalks, you can build a better project that benefits you,

improves the neighborhood, and protects natural resources.

Guide for:

Developers

Builders

Planners

Landscape Architects

Architects

Engineers


T a b l e o f c o n T e n T s

2 Standard Urban Stormwater Mitigation Plan (SUSMP)

3 Site-Specific Mitigation Plan (SSMP)

4 SUSMP and Site-Specific Mitigation Plan Submittal

6 Examples of Best Management Practices (BMP’s)

8 SUSMP Infiltration Requirements and Guidelines

1

secTion/elevaTion

ParkinG loT infilTraTion swale

2

2 0 0 9 G u i d e f o r d e v e l o P e r s & d e s i G n e r s

standard urban stormwater Mitigation Plan

standard urban stormwater Mitigation Plan (susMP)

Project applicants are required to prepare and

implement a standard urban stormwater Mitigation

Plan (SUSMP) when their projects fall into any of

these categories:

• Single-family hillside residential developments

with grading on slopes of 25% or greater

• Housing developments of 10 or more dwelling

units (including single-family tract developments)

• Industrial/commercial developments with one

acre or more of impervious surface area

• Automotive service facilities*

• Retail gasoline outlets*

• Restaurants*

• Parking lots of 5,000 square feet or more of

surface area or with 25 or more parking spaces

The state of california requires all applicable

new development and redevelopment projects

to maximize the percentage of pervious surfaces

(surfaces that allow water to penetrate the ground

below) and minimize the amount of stormwater

drained to impervious surfaces (like pavement and

sidewalks) and into storm drains. (nPdes Permit

no. cas004001)

• Projects with 2,500 square feet or more of

impervious area that are located in, directly

adjacent to, or draining directly to designated

Environmentally Sensitive Areas (ESA)

*Developments of less than 5,000 square feet in these catagories are

only subject to the prescriptive method specified in “The City of Los

Angeles Best Management Practices Handbook Part B, 3rd Edition”.

Porous PaveMenT rain barrel veGeTaTed swale

3

When a project does not fall into one of the SUSMP

categories but could still cause stormwater pollution,

the project applicant must prepare and implement a

Site-Specific Mitigation Plan. The following categories

of projects require a Site-Specific Mitigation Plan:

• Vehicle or equipment fueling areas

• Vehicle or equipment maintenance areas,

including washing and repair

• Commercial or industrial waste handling or

storage

• Outdoor handling or storage of hazardous

materials

• Outdoor manufacturing areas

• Outdoor food handling or processing

• Outdoor animal care, confinement, or slaughter

• Outdoor horticultural activities

• Major transportation projects

site-specific Mitigation Plan

redevelopment Project definition

Redevelopment projects are land-disturbing activities

that results in the creation, addition, or replacement of

5,000 square feet or more of impervious surface area

on an already developed site within the categories

listed above. Existing single-family “non-hillside”

structures are exempt from the redevelopment

requirements.


susMP and site-specific Mitigation Plan submittal

SUSMP or Site-Specific Mitigation Plans are required

as part of the project plan submittal package.

Project applicants should contact the City of Los

Angeles, Department of Public Works, Bureau of

Sanitation, Watershed Protection Division, SUSMP

Public Counter before submitting a building permit

application to the City’s Department of Building and

Safety. Contact information for the City’s SUSMP

Public Counter is located on the inside back cover or

at lastormwater.org.

Project plans submitted to the city of los angeles,

department of Public works and department of

building and safety must include:

• Site plan showing all property lines, existing

structures and proposed improvements

• Grading plan with existing and proposed contours,

and elevations

• Landscape plan

• Detail drawings of all Best Management Practices

(BMPs) including plan view, cross sections, and

any construction details

• Stenciling note and/or detail for any new catch

basins

• Trash enclosure details

• Stormwater runoff flow calculations

4

• Covenant and Agreement with Operation and

Maintenance Plan

Note: Developers may also need to submit plumbing

and architectural plans if the SUSMP BMP is located

within or adjacent to a building.

susMP and site specific Mitigation Plans shall

be included with the project plans. Only flow

calculations and the Covenant and Agreement with

the Operations and Maintenance Plan are to be

submitted on letter size page.

flow calculations: Stormwater BMPs must be

designed to capture the first 3/4-inch of a rain event.

Hydrology calculations must show the flow rate

(Qpm) and volume (Vm) of mitigated stormwater

runoff.

For more information, go to:

lastormwater.org, and click on “Businesses”,

then “For Developers”.

Plan Approval Process

Is project subject to SUSMP/SSMPrequirements?

Does project requireDiscretionary Action?

(environmental clearancezoning variance)

DBS Department of Building and Safety

WPD Watershed Protection Division

PCIS Plan Check and Inspection System

SOR Stormwater Observation Report

SUSMP Standard Urban Stormwater Mitigation Plan

SSMP Site-Specific Mitigation Plan

CITY PLANNING PLAN CHECK

NEW / REDEVELOPMENT

PROJECTS

Plan Check Engineer will issue permit after verifying that all corrections have been completed and clearances are obtained.

BUILDING & SAFETY PLAN CHECK

Projects will be inspected in accordance with the approved plan.Certificate of Occupancy will be issued when projects arecompleted, the SOR is submitted to WPD, and all required

clearances are obtained.

BUILDING & SAFETY INSPECTION

Is project subject to SUSMP/SSMPrequirements?

DBS PLAN CHECK

Applicant submits SUSMP/SSMPto WPD for review and approval.

APPLICANT

WPD will review SUSMP/SSMPand applicable documents, stamp

approved plan, and return to applicant.

WPD will clear project in PCIS.

WPD PLAN REVIEW

Plan Check Engineer will issuecorrections sheet which will referapplicants to WPD for clearance

of stormwater requirements.

Plan Check Engineer will enter intoPCIS that WPD clearance is required

prior to issuance of permit.

DBS PLAN CHECK CORRECTIONS

Imposes stormwater requirements aspart of discretionary review processand advise applicant to contact WPDfor SUSMP/SSMP requirements and

implementation plan.

CITY PLANNING

Final clearance for all conditions.

CITY PLANNING

Yes

YesYes

No

No No

5


examples of

best Management PracticesYou can build protection for Mother nature into

your plans by including features that:

• Allow rainwater and irrigation runoff to infiltrate

into the ground (first priority)

• Reduce runoff that leaves the property and drains

into gutters and storm drains

• Capture and reuse rainwater on the property

• Prevent erosion

• Keep trash and oil, grease and other pollutants

out of storm drains

The followinG exaMPles show how these helpful

design features, also called bMPs, look and work. Here

are great ways to prevent stormwater pollution, and

help project applicants prepare SUSMPs and SSMPs.

Other solutions are welcomed, as long as they curb

stormwater pollution and help protect Los Angeles’

natural resources.

visit

lastormwater.org

to get more ideas.

veGeTaTed sYsTeMs (biofilters) such as swales and

grass filter strips are designed to convey and treat ei-

ther shallow flow or sheet flow runoff. They are of-

ten densely vegetated, uniformly graded areas that

intercept sheet runoff from impervious surfaces such

as parking lots, roadways, and rooftops. Vegetated

swales are designed to slowly convey stormwater run-

off, and in the process trap pollutants, promote bio-

filtration, and reduce flow velocities.

infilTraTion sYsTeMs capture runoff and allow

it to seep into the ground. This reduces the volume

of water that is discharged to receiving water bod-

ies, thereby reducing some of the potential impacts

caused by excessive stormwater flow as well as in-

creased pollutant concentrations in the receiving

waters. Infiltration systems include infiltration ba-

sins, permeable pavement systems, and infiltration

trenches/swales, or dry wells.

6

how to build protection for mother nature into your project

Documents