Storm WaterRegulation Review & UpdateDan Bogoevski, Ohio EPA Northeast District Office

Summit SWCD Workshop

October 9, 2019

Today’s Agenda

• Sizing the skimmer drawdown orifice

• Applying the WQV formula

• Use of existing regional ponds to meet post-construction requirements

• Submitting NOIS• Multi-phase projects• Tree clearing in preparation for development• Borrow or spoil areas

• MS4 permit update

Where to Find Guidance Documents

• https://epa.ohio.gov/dsw/storm/index

• Click “Construction Activities” tab & “Technical Assistance” subtab

• Materials available include

• Rainwater & Land Development manual and related data sheets

• Post-construction Q&A documents

• WQv & RR calculator spreadsheets

• Alternative post-construction BMP request submittal form and guidance

Sizing Skimmers & Drawdown Orifices

• Ohio EPA’s requirements for sediment basins• Sediment Storage Volume

• Retained volume below the invert of skimmer

• 1000 ft3/acre of disturbed area to sediment basin

• Does not drain…remains in pond

• Dewatering Volume• Detained volume above the invert of

skimmer• 1800 ft3/acre of total contributing

drainage area to sediment basin• Skimmer orifice sized to drain in 48 hr

to 7 days

Sediment Basin Outlet Detail

Sediment Storage Volume

Dewatering Volume

Sediment Basin Outlet Detail

Actual Elevation to Store Required Dewatering Volume

What if…

Provided Elevation to Store Dewatering VolumeH

h

Which “h” do you use to size the dewatering orifice of the skimmer?

One more lesson on skimmers…

Faircloth Skimmer Marlee Float Skimmer Delaware Skimmer

Skimmers are not interchangeable. If you must install a different skimmer than what is specified in the approved SWP3, you must re-run sizing calculations and amend the SWP3.

Calculating the WQv

• New development

• Use Equation 1: WQv = Rv * P * A/12

• Rv = 0.05 + 0.9 * i

• Area = Total Disturbed Area (aka Area on NOI)

• Redevelopment

• Use Equation 3: WQv = [(Rv1*0.20) + (Rv2 – Rv1)] * P * A/12

• Rv1 = Volumetric runoff coefficient for existing conditions

• Rv2 = Volumetric runoff coefficient for proposed conditions

• Area = Total Disturbed Area (aka Area on NOI)

• Sizing of BMP

• Use Equation 1: WQv=Rv * P * A/12

• Area = Total Contributing Drainage Area to the BMP (include off-site areas that drain to BMP)

Applying the WQv FormulaProject Description: The proposed development will remove an existing parking lot from the front of the building and create a new parking lot on the west side of the buildings. Part of the new parking lot is already existing impervious area.

What equation do we use?What equation do we use?

Equation 3: WQv = P * A * [Rv1*0.2) + (Rv2-Rv1)]/12

Existing Conditions Proposed Conditions

Applying the WQv Formula

• Property Area = 4.58 ac

• Disturbed Area = 1.65 ac

• Impervious Area = 0.71 ac

Existing Conditions

What is Rv1?What is Rv1?

i1 = 0.71/1.65 = 0.43

Rv1 = 0.05 + 0.9 * i1 = 0.05 + (0.9 * 0.43) = 0.44

Applying the WQv Formula

Disturbed Area Totals =0.17 + 0.22 + 0.26 + 0.94 + 0.06 = 1.65 ac

Impervious Area Totals = 0.15 + 0.22 + 0.16 + 0.57 + 0.05 = 1.15 ac

Proposed Condition

Applying the WQv Formula

Proposed Conditions

• Property Area = 4.58 ac

• Disturbed Area = 1.65 ac

• Impervious Area = 1.15 ac

What is Rv2?What is Rv2?

i2 = 1.15/1.65 = 0.70

Rv2 = 0.05 + 0.9 * i2 = 0.05 + (0.9 * 0.70) = 0.68

What is the WQv Requirement?

WQv = P * A * [(Rv1*0.2) + (Rv2 – Rv1)]/12

What is P?P = 0.90 inches….ALWAYS

What area do we use?A = 1.65 acres…Total Disturbed Area

From previous calculationsRv1 = 0.44Rv2 = 0.68

WQv = 0.9 * 1.65 * [(0.44*0.2) + (0.68-0.44)]/12 = 1765 ft3

Or, use Ohio EPA’s spreadsheet

Sizing the BMP

What drainage area do we use?

Post-Construction BMP: A wet extended detention basin will be used to treat runoff from Area 4

A. Total Disturbed Area = 1.65 acres

B. Total Contributing Drainage Area to BMP = 1.09 acres

C. Total Impervious Area = 1.15 acres

E. Size of Drainage Area 4 = 0.94 acres

What is Rv?iBMP = 0.57/1.09 = 0.53 therefore, Rv = 0.05 + (0.9 * 0.53) = 0.53

D. Impervious Area in Drainage Area 4 = 0.57 acres

What formula do we use?

Equation 1: WQv = P * Rv * A/12 = 0.9*0.53*1.09/12 = 1887 ft3

Does the Design Meet NPDES Requirements?

WQv Required

1765 ft3

WQv Provided

1887 ft3

YES

>

Use of Regional BMP for WQv Requirement

• NPDES permit states a regional storm water BMP may be used to meet the post-construction requirement if• The BMP meets the design requirements for treating the WQv; and

• Legal agreement is established through which the regional BMP owner or operator agrees to provide this service in the long term.

• Design information for these facilities must be provided in the SWP3• Includes contributing drainage area, capacities, elevations, outlet details and

drain times

Use of Regional BMP for WQv Requirement

9.07-acre site

Site

Regional Pond

Drainage area to regional pond = 174.05 acres

Reviewing the SWP3

• Regional pond owned by another party

• No legal agreement included in SWP3

• Modifications for WQv only for 8.05 acres disturbed within 9.07-acre site

Regional Pond Outlet Structure

Use of Regional BMP for WQv Requirement

Does the proposal meet NPDES requirements?

NO

Pond must be modified to treat WQv for 174.05 acres, i.e., total contributing drainage area

Legal agreement must be provided to ensure use.Responsibilities for long-term maintenance must be clear.

Submitting NOIs

• All operators must submit an NOI

• NOI by Developer

• Co-Permittee NOI by Operator(s) with control over day-to-day operations required to comply with SWP3 and NPDES permit• General Contractor• Construction Management Company

• Individual Lot NOI by Homebuilders in residential subdivisions

Submittal of NOIs is not optional.Failure to submit is a violation of Ohio Revised Code 6111.04 (A).

Submitting NOIs – Commercial Subdivision

• 9.07-acre commercial property to be subdivided into four parcels

• Developer installed access road, utilities and did mass grading

• Each parcel will be developed independently but share a post-construction BMP

Submitting NOIs - Commercial Subdivision

How many NOIs should be submittedthrough the course of project

development?Lot Area

A 0.92

B 0.94

C 1.66

D 5.55

Total 9.07

5 NOIs in total1. Developer with Plan for Mass Grading2. Developer of Parcel A3. Developer of Parcel B4. Developer of Parcel C5. Developer of Parcel D

“Larger common plan of development or sale” is 9.07 acres.Thus, development on all parcels is a regulated.

Submitting NOIs – Multi-Phase Projects

Scenario: Developer is only clearing trees in preparation for a future four-phase subdivision.

How many NOIs should be submitted?

Multiple, but just how many depends

Separate SWP3 = Separate NOI

NOI only covers the construction activity shown in the associated SWP3. Disturbed areas will need to be stabilized after tree clearing is completed. Permit coverage should be terminated once vegetation ≥ 70%

Submitting NOIs –Borrow or Spoil Areas

• Project NOI covers if serving a single project• Area is related to project• Will not operate beyond the

completion of the project• SWP3 includes controls for borrow or

spoil area• Does not have to be contiguous to

project

• Develop separate SWP3 and submit separate NOI if serving multiple projects and area will disturb ≥ 1 acre

MS4 Permit Update

• Expired permit remains in effect

• New permit still in draft

• Once completed, US EPA Region 5 must review and approve

• Up to 35 days to approve or comment

• Public notice follows

• 45-day comment period

• Agency must prepare a Responsiveness Summary in response to comments (which may result in changes to permit requirements)

• Don’t anticipate permit renewal before Spring 2020

Potential Changes Being Discussed

• Updates to local regulations to meet or exceed current Ohio EPA requirements

• Added performance standards to better define compliance with TMDLs applicable to each community• Example: Public education program must target pollutant of concern

• Improving reporting requirements for illicit discharge tracking and elimination activities

• Adding a performance standard for long-term maintenance programs

• Clarifying inspection requirements for municipal service facilities

• Electronic submittal of annual reports mandatory

Storm Water Program Contacts

Dan Bogoevski

daniel.Bogoevski@epa.ohio.gov

(330) 963-1145

Laura Shriverlaura.shriver@epa.ohio.gov

(330) 963-1136

???????????dean.stoll@epa.ohio.gov

(330) 963-1197

Laura Shriver

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Dan Bogoevski