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III. Overview of the Virginia Stormwater Regulations. General Stormwater Training Workshop. Topics. Implementation Grandfathering Time Limits General Criteria Technical Criteria Quality Quantity Channel protection Flood Protection. Implementation .

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iii overview of the virginia stormwater regulations

III. Overview of the Virginia Stormwater Regulations

General Stormwater Training Workshop

topics
Topics
  • Implementation
  • Grandfathering
  • Time Limits
  • General Criteria
  • Technical Criteria
    • Quality
    • Quantity
      • Channel protection
      • Flood Protection
implementation
Implementation

The Soil and Water Conservation Board passed a motion authorizing the development of a NOIRA on July 21, 2005.

Completed in two separate regulatory actions

  • Part 13-Fees, effective February 3, 2010
  • Parts 1, 2 and 3-Definitions, Technical Criteria and Local Programs, effective September 13, 2011.

Included delayed implementation and grandfathered sections to establish stormwater programs.

4vac50 60 final stormwater regulations september 13 2011
4VAC50-60 Final Stormwater Regulations (September 13, 2011)

PART I (Definitions)

4VAC50-60-10 Definitions

PART II

4VAC50-60-20 Purpose

4VAC50-60-30 Applicability

4VAC50-60-40 Authority

4VAC50-60-45 Implementation date

4VAC50-60-46 General objectives

4VAC50-60-47 Applicability of other laws and regulations

4VAC50-60-47.1 Time limits on applicability of approved design criteria

4VAC50-60-48 Grandfathering

4VAC50-60-51 Chesapeake Bay Preservation Act land-disturbing activity

PART IIA (Administrative)

4VAC50-60-53 Applicability

4VAC50-60-54 Stormwater pollution prevention plan requirements

4VAC50-60-55 Stormwater management plans

4VAC50-60-56 Pollution prevention plans

4VAC50-60-57 Requesting an exception

4VAC50-60-58 Responsibility for long-term maintenance of permanent stormwater management facilities

4VAC50-60-59 Applying for VSMP permit coverage

PART IIB (Technical Criteria)

4VAC50-60-62 Applicability

4VAC50-60-63 Water quality design criteria requirements

4VAC50-60-65 Water quality compliance

4VAC50-60-66 Water quantity

4vac50 60 final stormwater regulations september 13 20111
4VAC50-60 Final Stormwater Regulations (September 13, 2011)

PART IIB (Cont)

4VAC50-60-69 Offsite compliance options

4VAC50-60-72 Design storms and hydrologic methods

4VAC50-60-74 Stormwater harvesting

4VAC50-60-76 Linear development projects

4VAC50-60-85 Stormwater management impoundment structures or facilities

4VAC50-60-92 Comprehensive stormwater management plans

Part IIIC (Grandfathered Projects)

4VAC50-60-93.1 Definitions

4VAC50-60-94 Applicability

4VAC50-60-95 General

4VAC50-60-96 Water quality

4VAC50-60-97 Stream channel erosion

4VAC50-60-98 Flooding

PART III

4VAC50-60-100 Applicability

4VAC50-60-102 Authority

4VAC50-60-103 Stormwater program administrative authority requirements for Chesapeake Bay Preservation Act land-disturbing activities

Part IIIA (Local Programs)

4VAC50-60-104 Criteria for programs operated by a stormwater program administrative authority

4VAC50-60-106 Additional requirements for local stormwater management programs

4VAC50-60-108 Stormwater management plans

4VAC50-60-112 Long-term maintenance of permanent stormwater management facilities

4VAC50-60-114 Inspections

4VAC50-60-116 Enforcement

4vac50 60 final stormwater regulations september 13 20112
4VAC50-60 Final Stormwater Regulations (September 13, 2011)

Part IIIA (Cont.)

4VAC50-60-118 Hearings

4VAC50-60-122 Exceptions

4VAC50-60-126 Reports and recordkeeping

Part IIIB (DCRs Program Reviews)

4VAC50-60-142 Authority and applicability

4VAC50-60-144 Local stormwater management program review

Part IIIC (Board authorization of VESCPs)

4VAC50-60-146 Authority and applicability

4VAC50-60-148 Local stormwater management program administrative requirements

4VAC50-60-150 Authorization procedures for local stormwater management programs

4vac50 60 final stormwater regulations september 13 20113
4VAC50-60 Final Stormwater Regulations (September 13, 2011)

Part XIII (Fees)

4VAC50-60-700 Purpose

4VAC50-60-720 Authority

4VAC50-60-730 Applicability

4VAC50-60-740 Exemptions

4VAC50-60-750 Due dates for Stormwater Management (VSMP) Permits

4VAC50-60-760 Method of payment

4VAC50-60-770 Incomplete payments and late payment

4VAC50-60-780 Deposit and use of fees

4VAC50-60-790 General

4VAC50-60-800 Fee schedules for VSMP Municipal Separate Storm Sewer System new permit issuance

4VAC50-60-810 Fee schedules for major modification of MS4 individual permit requested by operator

4VAC50-60-820 Fees for an individual permit or coverage under the General Permit for Discharges of Stormwater from Construction Activities

4VAC50-60-825 Fees for the modification or transfer of individual permits or of registration statements for the General Permit for Discharges of Stormwater from Construction Activities

4VAC50-60-830 Permit maintenance fees

http://leg1.state.va.us/000/reg/TOC04050.HTM#C0060

part ii
Part II

4VAC50-60-40 through 4VAC 50-60-51

grandfathered projects 4vac50 60 48
Grandfathered Projects (4VAC50-60-48)

What is Grandfathering?

Means projects being subject to the Technical Criteria of Part II C (existing technical criteria) of the VSMP Regulations and NOT subject to Part IIB (new technical criteria).

summary of the key differences in application
Existing Part II C

Impervious Surface

0.5 inches of Runoff

Average land cover condition

10% reduction P

Simple Method, Blue Book, BMP’s

New Part II B

Forest/Open Space, Turf, Impervious

1.0 inches of Rainfall

0.41 lbs./ac/yr P

<1 acre-10% Reduction P,

>1 acre -20% Reduction P

Runoff Reduction, Clearing House BMP’s

Summary of The Key Differences in Application

Land Use(s)

Event

New Design Criteria

Redevelopment Criteria

ComplianceMethodology

grandfathered projects 4vac50 60 481
Grandfathered Projects (4VAC50-60-48)

Land-disturbing activities where the following was approved by a locality prior to July 1, 2012:

  • a currently valid proffered or conditional zoning plan,
  • preliminary or final subdivision plat,
  • preliminary or final site plan or
  • zoning with a plan of development,
  • or any document determined by the locality as being equivalent

and

  • Coverage under the VSMP General Permit was not obtained prior to July 1, 2014.

For land disturbing activities that are Grandfathered, construction must be complete by June 30, 2019 or portions of the project not under construction shall become subject to the new technical criteria of Part II B.

grandfathered local state and federal projects 4vac50 60 48 b
Grandfathered local, state and federal projects (4VAC50-60-48.B.)

A local, state or federal project is grandfathered until June 30, 2019 when:

There has been an obligation of locality, state, or federal funding, in whole or in part, prior to July 1, 2012, or for which the department has approved a stormwater management plan prior to July 1, 2012

If bonds or public debt financing has been secured prior to July, 1 2012, projects shall be grandfathered without a completion date.

time limit on applicability of approvals 4vac50 60 47 1
Time limit on applicability of approvals (4VAC50-60-47.1.)

The approved post development design is valid for construction only for the remaining portion of the General Permit cycle under which it was originally permitted (up to 5-years) PLUS two additional permit cycles (10-years) unless:

VSMP permit coverage lapses (failure to reapply)

or

Two additional permit cycles have passed

Portions of the project not under construction are required to meet any new technical criteria adopted since original permit coverage was issued.

example of the time limit on approved plan
Example of the time limit on approved plan

A sub-division registers under the VSMP General Permit on July 12, 2013.

The post-development criteria applicable to the sub-division remains applicable for the remaining portion of that permit cycle (until 2014) plus two additional (2014-19, 2019-24).

Any portions of the sub-division not under construction July 1, 2024 must meet the post development design criteria in place at that time

part ii a general administrative criteria
Part II A General Administrative Criteria

4VAC50-60-53 through 4VAC 50-60-59

(54) Stormwater Pollution Prevention Plan (SWPPP)

A. Erosion and Sediment Control Plan

B. Stormwater Management Plan

C. Pollution Prevention Plan

D. Additional requirements to meet an established TMDL

(55) Stormwater Management Plans

(56) Pollution Prevention Plans

(57) Exceptions

(58) Long-term Maintenance

(59) Applying for VSMP coverage

part ii b technical criteria
Part II B Technical Criteria

4VAC50-60-63 through 4VAC50-60-92

4vac50 60 63 water quality
4VAC50-60-63 Water Quality
  • New development. The total phosphorus load of a new development project shall not exceed 0.41 pounds per acre per year
  • Development of prior developed lands.

a. land disturbing > 1 acre 20% reduction in P load

b. land disturbing < 1 acre 10% reduction in P load

c. net increase in impervious new criteria applied to the increased impervious area

d. 20% P load reduction for linear projects in prior developed lands

e. No reduction below 0.41 pounds per acre per year

basis for the 0 41 lbs ac yr phosphorus load
Basis for the 0.41 lbs/ac/yr Phosphorus load

4VAC50-60-63 1. New Development. The Total phosphorus load of a new development project shall not exceed 0.41 pounds per acre per year.

Statewide Requirement Based on Percentage of Impervious Cover and State Soil Geographic Data Base average soil cover

(assumes 10% impervious cover, 30% turf, 60% forest)

4vac50 60 65 water quality compliance
4VAC50-60-65 Water Quality compliance
  • Must be accomplished using the Virginia Runoff Reduction Method (to be discussed later today)
  • Lists a set of approved BMPs (found on Clearinghouse Website)
  • Establishes a review process for other BMPs
  • Allows local program to establish limitations for BMP use
  • Sites draining to two or more HUCs
  • Offsite alternatives requirements
4vac50 60 65 water quality compliance1
4VAC50-60-65 Water Quality compliance

Incorporated by reference: “Virginia Runoff Reduction Method: Instructions & Documentation, March 28, 2011.”

This method addresses the use of land use types (impervious vs forested/pasture/ open space/turf) , and uses rainfall (1 inch) instead of runoff (0.5 inch) in determining runoff and infiltrates the runoff to the maximum extent possible.

part ii b technical criteria1
Part II B Technical Criteria

4VAC50-60-66 Water quantity

part ii b technical criteria2
Part II B Technical Criteria

4VAC50-60-66 Concentrated stormwater flow shall be released into a Stormwater Conveyance System that meets the criteria of this sub-section from the point of discharge to a point to the limits of analysis (discussed later).

what is a stormwater conveyance system
What is a Stormwater Conveyance System?

4VAC50-60-10 defines it as; “a combination of drainage components that are used to convey stormwater discharge either within or downstream of the land disturbing activity”

  • Manmade conveyance system: pipe, ditch or vegetated swale
  • Natural stormwater conveyance system: includes the main channel and the flood-prone area adjacent to the main channel
  • Restored stormwater conveyance system: has been designed and constructed using natural design concepts and includes main channel and the flood-prone area adjacent to the channel
4vac50 60 66 channel protection
4VAC50-60-66 Channel Protection

Manmade Stormwater Conveyance Systems

  • Shall convey the post development peak flow rate without causing erosion to the system (2-year 24-hour storm) or
  • Treat as a natural system (energy balance equation)

Restored Stormwater Conveyance Systems

  • Shall convey post development peak discharge consistent with the design criteria of the restored conveyance system, or
  • Treat as a natural system (energy balance equation)

Natural Stormwater Conveyance Systems

  • Use energy balance equation (1 year 24 hour storm)
slide25

Energy equation (40VAC50-60-65)

Qpost ≤ I.F. x (Qpre x RVpre)/RVpost

Where

  • Qpre=Pre-development peak flow rate (cfs)
  • RVpre= Pre-development runoff volume (in.)
  • Qpost= Post-development peak flow rate (cfs)
  • RVpost= Post development runoff volume (in.)
  • I.F. = Improvement factor (0.8 for sites>1 acre, 0.9 for sites < 1 acre
slide26

Energy equation (40VAC50-60-65)

Qpre x RVpre ~ Qpost x RVpost

or

Energypre ≈ Energypost

restrictions
Restrictions

Under no conditions shall Qpost > Qpre

nor

shall Qpostbe less than that calculated as Qforest

as calculated in (Qforest *RVforest)/ RvPost

4vac50 60 66 b 4 limits of analysis
4VAC50-60-66. B.4. Limits of analysis
  • … site’s contributing drainage area is less than or equal to 1.0% of the total watershed, or
  • … site’s peak flow rate is less than or equal to 1.0% of the existing peak flow rate (based on a one-year 24 hour storm)
40vac50 60 66 c flood protection
40VAC50-60.66.C. Flood protection

Discharge into Stormwater conveyance systems that:

  • do not experience flooding: confine peak flow of the 10-year storm within conveyance.
  • that do experience flooding: do as above, or release 10-year post development peak storm at a rate that is less than the 10-year pre development storm rate.
4vac50 60 66 d e and f
4VAC50-60-66.D, E and F
  • Increased volumes of sheet flow must be identified and evaluated for impacts on down-gradient properties or resources…
  • All developed land is assumed to be in good hydrologic condition
  • Pre-development and post-development site conditions shall be verified by inspections, surveys and maps. Calculations shall be consistent with good engineering practices.
4vac50 60 72 design storms and hydrologic methods
4VAC50-60-72. Design Storms and Hydrologic Methods
  • 1, 2 and 10-year 24 hour design storms
  • Use existing site conditions and ultimate developed conditions in hydrologic analysis
  • Use of standard hydrologic methods (TR-55, TR-20, etc)
  • Authority “may allow” use of rational method when <200 acres to calculate peak discharge
  • Authority “may allow” use of modified rational method when <200 acres to calculate volumetric flows of stormwater.
4vac50 60 74 stormwater harvesting
4VAC50-60-74. Stormwater Harvesting

Encourages stormwater harvesting and reuse

4VAC50-60-85. Impoundments

Shall be designed to follow Dam Safety Regulations (4VAC50-20) or be designed for structural integrity for a 100-year storm event

Specifickarst requirements for construction in karst area and discharge into a karst feature