Rhode Island

RHODE ISLAND STORMWATER DESIGN AND INSTALLATION STANDARDS MANUAL

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Jurisdiction level

state

“RHODE ISLAND DEPARTMENT OF ENVIRONMENTAL MANAGEMENT AND COASTAL RESOURCES MANAGEMENT COUNCIL”
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State

Rhode Island

“The RI Stormwater Design and Installation Standards Manual”
Effective Date Page

Version / edition

Amended March 2015

“Amended March 2015”
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Adoption / effective date

Not found in document

“Effective Date: _______________”
Effective Date Page

Last revised date

March 2015

“Amended March 2015”
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Relationship to state manual

independent

“RHODE ISLAND STORMWATER DESIGN AND INSTALLATION STANDARDS MANUAL”
Title Page

Design Criteria

Design storm return periods (years)

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

“1-Year 2-Year 5-Year 10-Year 25-Year 50-Year 100-Year”
Table 3-1, Page 3-1

Water quality volume method

Equivalent to the runoff associated with the first 1.2 inches of rainfall over the impervious surface (i.e., 1 inch of runoff), calculated as WQv = (1") (I) / 12

“The required WQv, which results in the capture and treatment of the entire runoff volume for 90 percent of the average annual storm events, is equivalent to the runoff associated with the first 1.2 inches of rainfall over the impervious surface (i.e., 1 inch of runoff).”
Section 3.3.3, Page 3-13 to 3-14

Peak flow calculation method(s)

TR-55, TR-20, Rational Method

“The models TR-55 or TR-20 (or approved equivalent) shall be used for determining the CPv. ... The Rational Method may be used for sizing the conveyance system.”
Section 3.3.4, Page 3-17

Required hydrologic/hydraulic software

TR-55, TR-20

“The models TR-55 and TR-20 (or approved equivalent) will be used for determining the required storage and outlet structures”
Section 3.3.5, Page 3-19

Approved BMP categories

Wet Vegetated Treatment Systems (WVTS), Infiltration Practices, Filtering Systems, Green Roofs, Open Channel Systems

“The five groups of structural BMPs include (1) Wet Vegetated Treatment Systems (WVTS), (2) Infiltration Practices, (3) Filtering Systems, (4) Green Roofs, and (5) Open Channel Practices.”
Section 1.3, Page 1-5