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 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)
PART I (Definitions)4VAC50-60-10 Definitions
PART II4VAC50-60-20 Purpose4VAC50-60-30 Applicability4VAC50-60-40 Authority4VAC50-60-45 Implementation date4VAC50-60-46 General objectives4VAC50-60-47 Applicability of other laws and
regulations4VAC50-60-47.1 Time limits on applicability of
approved design criteria4VAC50-60-48 Grandfathering4VAC50-60-51 Chesapeake Bay Preservation Act
land-disturbing activityPART IIA (Administrative)
4VAC50-60-53 Applicability
4VAC50-60-54 Stormwater pollution prevention plan requirements
4VAC50-60-55 Stormwater management plans4VAC50-60-56 Pollution prevention plans4VAC50-60-57 Requesting an exception4VAC50-60-58 Responsibility for long-term
maintenance of permanent stormwater management facilities
4VAC50-60-59 Applying for VSMP permit coveragePART IIB (Technical Criteria)
4VAC50-60-62 Applicability4VAC50-60-63 Water quality design criteria
requirements4VAC50-60-65 Water quality compliance4VAC50-60-66 Water quantity
4VAC50-60 Final Stormwater Regulations (September 13, 2011)
PART IIB (Cont)4VAC50-60-69 Offsite compliance options4VAC50-60-72 Design storms and hydrologic
methods4VAC50-60-74 Stormwater harvesting4VAC50-60-76 Linear development projects4VAC50-60-85 Stormwater management
impoundment structures or facilities4VAC50-60-92 Comprehensive stormwater
management plansPart IIIC (Grandfathered Projects)
4VAC50-60-93.1 Definitions4VAC50-60-94 Applicability4VAC50-60-95 General4VAC50-60-96 Water quality4VAC50-60-97 Stream channel erosion4VAC50-60-98 Flooding
PART III4VAC50-60-100 Applicability4VAC50-60-102 Authority4VAC50-60-103 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 authority4VAC50-60-106 Additional requirements for local
stormwater management programs4VAC50-60-108 Stormwater management plans4VAC50-60-112 Long-term maintenance of
permanent stormwater management facilities4VAC50-60-114 Inspections4VAC50-60-116 Enforcement
4VAC50-60 Final Stormwater Regulations (September 13, 2011)
Part IIIA (Cont.)4VAC50-60-118 Hearings4VAC50-60-122 Exceptions4VAC50-60-126 Reports and recordkeeping
Part IIIB (DCRs Program Reviews)4VAC50-60-142 Authority and applicability4VAC50-60-144 Local stormwater management
program reviewPart IIIC (Board authorization of VESCPs)
4VAC50-60-146 Authority and applicability4VAC50-60-148 Local stormwater management
program administrative requirements4VAC50-60-150 Authorization procedures for local
stormwater management programs
4VAC50-60 Final Stormwater Regulations (September 13, 2011)
Part XIII (Fees)4VAC50-60-700 Purpose4VAC50-60-720 Authority4VAC50-60-730 Applicability4VAC50-60-740 Exemptions4VAC50-60-750 Due dates for Stormwater
Management (VSMP) Permits4VAC50-60-760 Method of payment4VAC50-60-770 Incomplete payments and late
payment4VAC50-60-780 Deposit and use of fees4VAC50-60-790 General4VAC50-60-800 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 II4VAC50-60-40 through 4VAC 50-60-51
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 ApplicationExisting 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
Land Use(s)
Event
New Design Criteria
Redevelopment Criteria
Compliance Methodology
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.)
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.)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
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
4VAC50-60-53 through 4VAC 50-60-59(54) Stormwater Pollution Prevention Plan (SWPPP)
A. Erosion and Sediment Control PlanB. Stormwater Management PlanC. Pollution Prevention PlanD. 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 Criteria4VAC50-60-63 through 4VAC50-60-92
4VAC50-60-63 Water Quality1. New development. The total phosphorus load of a new
development project shall not exceed 0.41 pounds per acre per year
2. Development of prior developed lands.a. land disturbing > 1 acre 20% reduction in P loadb. land disturbing < 1 acre 10% reduction in P loadc. net increase in impervious new criteria applied to the increased impervious aread. 20% P load reduction for linear projects in prior developed landse. No reduction below 0.41 pounds per acre per year
Basis for the 0.41 lbs/ac/yr Phosphorus load
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)
4VAC50-60-63 1. New Development. The Total phosphorus load of a new development project shall not exceed 0.41 pounds per acre per year.
4VAC50-60-65 Water Quality complianceA. Must be accomplished using the Virginia Runoff
Reduction Method (to be discussed later today)B. Lists a set of approved BMPs (found on
Clearinghouse Website)C. Establishes a review process for other BMPsD. Allows local program to establish limitations for BMP
useE. Sites draining to two or more HUCsF. Offsite alternatives requirements
4VAC50-60-65 Water Quality complianceIncorporated 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.
Conservation
OpenDrainage
RainGardens
AmendedSoils
RainBarrel
ReducedImperviousness
LID SiteLID SitePorous
Pavement
Create a Hydrologically Functional LotUnderdrain Gravel
n = 0.40
Soil Media Storage
n = 0.25
Surface Ponding Storage
n = 1.0
Underdrain Gravel
n = 0.40
Soil Media Storage
n = 0.25
Underdrain Gravel
n = 0.40
Soil Media Storage
n = 0.25
Surface Ponding Storage
n = 1.0
Part II B Technical Criteria4VAC50-60-66 Water quantity
Part II B Technical Criteria4VAC50-60-66 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?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”
1. Manmade conveyance system: pipe, ditch or vegetated swale2. Natural stormwater conveyance system: includes the main
channel and the flood-prone area adjacent to the main channel3. 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 ProtectionManmade 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)
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
Energy equation (40VAC50-60-65)
Qpre x RVpre ~ Qpost x RVpost
or
Energypre ≈ Energypost
Energy equation (40VAC50-60-65)
RestrictionsUnder no conditions shall Qpost > Qpre
norshall Qpost be less than that calculated as Qforest
as calculated in (Qforest *RVforest )/ RvPost
4VAC50-60-66. B.4. Limits of analysis
a. … site’s contributing drainage area is less than or equal to 1.0% of the total watershed, or
b. … 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 protectionDischarge into Stormwater
conveyance systems that:1. do not experience flooding:
confine peak flow of the 10-year storm within conveyance.
2. 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 FD. Increased volumes of sheet flow must be
identified and evaluated for impacts on down-gradient properties or resources…
E. All developed land is assumed to be in good hydrologic condition
F. 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 MethodsA. 1, 2 and 10-year 24 hour design stormsB. Use existing site conditions and ultimate developed
conditions in hydrologic analysisC. Use of standard hydrologic methods (TR-55, TR-20,
etc)D. Authority “may allow” use of rational method when
<200 acres to calculate peak dischargeE. Authority “may allow” use of modified rational method
when <200 acres to calculate volumetric flows of stormwater.
4VAC50-60-74. Stormwater HarvestingEncourages stormwater harvesting and reuse
4VAC50-60-85. ImpoundmentsShall be designed to follow Dam Safety
Regulations (4VAC50-20) or be designed for structural integrity for a 100-year storm event
Specific karst requirements for construction in karst area and discharge into a karst feature
Questions?
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