DRAINAGE STUDY/STORMWATER CONTROL PLAN
for
[Name of Project]
[Project Address]
Watsonville, California
DRAFT
[Date]
Note: This template is provided as a convenience only. It must be adapted as
needed to meet requirements for a particular development project. Refer to the
current version of City of Watsonville Low Impact Development, Best Management
Practice Design Guidance for Hydromodification Management and Stormwater Quality.
Stormwater Control Plan Template
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Version 29 September 2008
TABLE OF CONTENTS
I.
II.
Project Setting ..............................................................................................................3
I.A.
Project Description and Location ................................................................................................................ 3
I.B.
Existing Site Condition .................................................................................................................................. 3
I.C.
Opportunities and Constraints for Stormwater Control ......................................................................... 3
Site Design ....................................................................................................................3
II.A.
Measures to Optimize the Site Layout ........................................................................................................ 3
II.B.
Measures to Limit Paving and Roofs .......................................................................................................... 3
II.C.
Measures to Direct Drainage to Landscaped Areas.................................................................................. 3
II.D.
Bioretention Facilities ..................................................................................................................................... 4
III. Calculations and Documentation .................................................................................4
III.A.
III.B.
Drainage Management Areas ........................................................................................................................ 4
III.A.1.
Self-Treating Areas
4
III.A.2.
Self-Retaining Areas 4
III.A.3.
Areas Draining to Self-Retaining Areas 4
III.A.4.
Areas Draining to Bioretention Facilities and Bioretention Facility Sizing
5
Bioretention Facilities ..................................................................................................................................... 5
IV. Source Control Measures .............................................................................................5
V.
Bioretention facility Operation and Maintenance .......................................................5
V.A.
V.B.
Means to Finance and Implement BMP Maintenance ............................................................................. 5
V.A.1.
Commitment to Execute any Necessary Agreements.
5
V.A.2.
Statement Accepting Responsibility for Interim Operation and Maintenance
V.A.3.
Stormwater Facilities Operation and Maintenance Plan
6
6
Summary of Maintenance Requirements .................................................................................................... 6
VI. Certification ..................................................................................................................6
Tables
Drainage Areas, Stormwater Facility Areas, and Calculations ......................................................................4
Figures
Figure 1. Location Map ..................................................................................................................................... 3
Stormwater Control Plan Exhibit (Attached)
Stormwater Control Plan Template
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Version 29 September 2008
I.
PROJECT SETTING
I.A. Project Description and Location
[Describe project, relationship to other projects, location, and neighborhood character].
[Describe work to be done].
I.B. Existing Site Condition
[Describe existing natural hydrologic features (depressions, watercourses, relatively undisturbed
areas) and significant natural resources. Refer to exhibit. Describe soil types and depth to
groundwater, existing surface
drainage, and significant trees.]
I.C. Opportunities and
Constraints for Stormwater
Control
[Opportunities might include low
areas, oddly configured or
otherwise unbuildable areas,
setbacks, easements, or buffers.]
[Constraints might include lowpermeability soils, high
groundwater, groundwater
pollution or contaminated soils,
steep slopes, geotechnical
instability, high-intensity land use,
heavy pedestrian or vehicle traffic,
or safety concerns.]
Figure 1. General Location of Project
II.
SITE DESIGN
[Describe overall approach to site design]
II.A.
Measures to Optimize the Site Layout
[Describe how the design defines the development envelope and protected areas, limits grading and
preserves natural landforms, sets back development from creeks, wetlands, and riparian habitats and
preserves significant trees. Note local ordinance requirements and compliance.]
II.B.
Measures to Limit Paving and Roofs
[Identify locations where permeable pavements will be substituted for impervious concrete or asphalt
paving. Also note use of green roofs.]
II.C.
Measures to Direct Drainage to Landscaped Areas
[Describe measures to disperse runoff to landscaped areas.]
Stormwater Control Plan Template
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Version 29 September 2008
II.D.
Bioretention Facilities
[Describe in general how and where bioretention facilities will be used.]
III. CALCULATIONS AND DOCUMENTATION
[Reference the Exhibit.]
III.A. Drainage Management Areas
[Explain the boundaries of each drainage area and where it drains to. Expand the tables below as
needed]
III.A.1. Self-Treating Areas
DMA Name
Area (square feet)
III.A.2. Self-Retaining Areas
DMA Name
Area (square feet)
III.A.3. Areas Draining to Self-Retaining Areas
DMA Name
Area
(square feet)
Post-project
surface type
Stormwater Control Plan Template
Runoff
factor
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Receiving selfretaining DMA
Receiving selfretaining DMA
Area (square feet)
Version 29 September 2008
III.A.4. Areas Draining to Bioretention Facilities and Bioretention Facility Sizing
DMA
Name
DMA
Area
(square
feet)
Postproject
surface
type
DMA
Runoff
factor
DMA
Area 
runoff
factor
Bioretention Facility Name
Facility
Sizing
factor
Minimum
Facility
Size
Proposed
Facility
Size
0.04
Total>
[Repeat the above table for each bioretention facility.]
III.B. Bioretention Facilities
[Describe each bioretention facility. Include preliminary design specifications and criteria to be used.
See the Guidance for Applicants.]
IV. SOURCE CONTROL MEASURES
[Describe potential sources of pollutants and corresponding source control measures, also tabulate.]
Potential Source of Pollutants
V.
Controls Incorporated into Project
BIORETENTION FACILITY OPERATION AND MAINTENANCE
V.A. Means to Finance and Implement BMP Maintenance
V.A.1. Commitment to Execute any Necessary Agreements.
[Obtain requirements from municipal staff.]
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Version 29 September 2008
V.A.2. Statement Accepting Responsibility for Interim Operation and Maintenance
[Applicant] accepts responsibility for interim operation and maintenance of stormwater treatment
and flow-control facilities until such time as this responsibility is formally transferred to a subsequent
owner.
V.A.3. Stormwater Facilities Operation and Maintenance Plan
[State intent to submit a Stormwater Facilities Operation and Maintenance Plan as required by the
local municipality.]
V.B. Summary of Maintenance Requirements
[Describe general maintenance requirements for the facilities planned. See Chapter 5 in the
Guidance for Applicants.]
VI. CERTIFICATION
The preliminary design of stormwater treatment facilities and other stormwater pollution control
measures in this plan are in accordance with the current edition of the Low Impact Development, Best
Management Practice Design Guidance for Hydromodification Management and Stormwater Quality, City of
Watsonville.
Stormwater Control Plan Template
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Version 29 September 2008