Virginia Regulatory Town Hall
Agency
Department of Environmental Quality
 
Board
State Water Control Board
 
Guidance Document Change: This guidance document has been developed to assist the public and the development community in determining the policies and procedures, which apply to land development in the Commonwealth of Virginia where DEQ serves as the Virginia Stormwater Management Program (VSMP) authority and/or the Virginia Erosion & Sediment Control Program (VESCP) authority. It contains information primarily concerned with the design guidelines for Erosion & Sediment Control Plans and Stormwater Management Plans.
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8/31/22  5:39 pm
Commenter: Dan Jamison, PE - Timmons Group

Guidance Memo 22-2012 COmments
 
  1. General Question: When is GM22-2021 Formally Effective as Guidance for development?
    • Guidance released for public comment on 8/1/2022, public comment period closes on 8/31/2022.

 

  1. General Question: Are there any limitations on the Dual Combined Administrator Selected for Site Plan Review when utilizing the streamlined plan review process?
    • Can they work for the same company as the sealing professional or do they have to be a 3rd party?

 

  1. 2.303 – Temporary Sediment Basin – D.
    • Where is the “Limits of Analysis” for “Manmade Stormwater Conveyance Systems” from an ESC perspective?
      • Is it where the “Manmade Stormwater Conveyance System” ties into the receiving “Natural Stormwater Conveyance System?”

 

  1. 2.306 – Topsoiling – A.
    • How many soil samples are necessary per acre?
      • The only guidance regarding soil sampling can be found in DEQ BMP Spec No. 4 – Soil Amendment and requires 1 soil sample to be conducted for every 5,000 sq. ft. of disturbance.  This equates to 9 tests/acre, which means for a site with 500 acres of disturbance – 4,500 tests would be necessary.
  1. 3.301 – Design Storms and Hydrologic Methods – A.
    • What criteria is needed to be met to prove compliance with Water Quantity utilizing the 2-year storm event?
      • Is the 2-year storm event only necessary for Safe Harbor or where stormwater releases to an existing “Manmade Stormwater Conveyance System?” 
      • Previously, it was our understanding that the Energy Balance must be met for the 1-year storm, flood protection requirements as spelled out in 0VAC25-870-66 C for the 10-year storm, and freeboard requirements per the BMP Manual were required to confirm the 10-year event is adequately detained, but there were not specific guidelines to what was needed for the 2-year storm.
  2. 3.302.1 – Channel Protection Computations – C & 3.303.1 – Flood Protection Computations – D
    • 2.a/2.b (Channel) & 1.a (Flood) – If the downstream limit of analysis is located off-site, how would field surveyed cross sections/visual inspections occur? 
      • Typically, adjacent landowners would prefer to not grant access to their property for development on other properties.  Without access, there is no way to determine where constrictions, changes in channel geometry, or natural slope changes occur.
  1. 3.302.3 – Discharges to Natural Stormwater Conveyance Systems – Definition
    • What is the definition of a “swale” in the context provided in the definition of a “Natural Stormwater Conveyance System” – “This includes any natural or perennial or intermittent streams, unimproved ephemeral channels, wetlands, or swales.”
    • Where are the “Limits of Analysis” for Natural Stormwater Conveyance Systems defined?  Per the old guidance, it stated that “Unless subdivision 3 of this subsection (Energy Balance Calculation) is utilized to show compliance with channel protection criteria…….”, but that appears to be excluded from the revised guidance.
  1. 3.302.3 – Discharges to Natural Stormwater Conveyance Systems – B&C
    • When the conditions for both B & C are met, which section of this code governs?
      • “Under no circumstances should Qdev > Qpre”, but also “Under no circumstances should Qdev be required to be less than the forested energy balance equation written as: Qforest x Unsupported image type. 
      • When Qforest x Unsupported image type. > Qpre, what should be selected as the allowable flow flow rate?
      •  
  1. 3.302.4 – Is there a preferred methodology for analysis of the 1-year flood prone area?
    • 2D Modelling software such as Flow2D or HEC-RAS or is creating a cross section and analyzing it using an application such as Flowmaster preferred?
  1. 3.302.5 – Is the “site” defined by the LOD, the lease limits, or the property boundary?
  1. 3.303 – Flood Protection
    • Is an analysis point/section required to be analyzed at every single point of discharge from the site? 
      • Previously, DEQ has required an analysis point to receive flow from 2-3 discharge points relative to the receiving “Natural Stormwater Conveyance System.” 
  1. 3.303.1.D. – Flood Protection Computations – 1.a/b.
    • Is Lidar acceptable for “Field Surveyed Cross Sections” or does it need to be field surveyed?
      • Lidar typically provides us with Bed and Bank of the channel and has provided the necessary information previously.
    • What should be included in the “narrative based on visual inspection?”
      • This section of requirements appears to fit more into “Channel Protection” analysis rather than “Flood Protection” as it is directly related to proving channel adequacy at points of constriction or areas with flatter (<1%) slopes.
  1. 1.100 – General – Paragraph #3 and 6.200 – Submission of Complete Plans – B.
    • Clarity is requested between “Initial Plan Acceptance (1.100) and “Plans Being Received” (6.200) as “Acceptance” is not adequately defined. 
      • Is acceptance once the plans have passed the completeness review?
      • Per paragraph 1.100, this directly effects which version of this guidance document the submitted plans will be held to.
  1. 5.200 – Pre – vs Post-Development Drainage Areas/Divides – B.
    • “Post-development drainage areas should deviate from the pre-development condition by no more than plus or minus 10%.”
      • Is there any flexibility with this requirement?  The only way to satisfy this criterion would be to vastly increase the number of on-site BMPs.
  1. 5.301.D – Who makes determination on “Previously disturbed soils?”
  1. 5.500 – Unconnected Impervious Areas
    • Do the required length and slopes from DEQ BMP Spec No. 1 – Disconnected Impervious apply to solar sites?  Additional Guidance would be beneficial to determine application for solar sites.
      • The length of flow and max slopes will have significant layout implications that will impact the electric production achievable on-site.
      • Flow is not released from the top of solar panels in a “Pipe system” or “Conduit” as it is from building rooftops, so one centralized receiving “Trench/Channel” will not receive all flow generated from the “Unconnected Impervious” surface.  How does this impact the application of Unconnected Impervious to solar sites?
  1. How should the VRRM be analyzed to account for HSG changes in areas with fill material/compaction?
    • Should they be run as a New Development spreadsheet or a ReDevelopment to get full pre-to-post analysis completed?
      • ReDevelopment spreadsheet will not allow for a change in HSG without generating an error message.
  1. 7.000 – Construction Record Drawings: what information would DEQ like to be provided with this? 
    • Is a Field Survey of the As-Built condition adequate or would updating the models and calculations be required as well?
CommentID: 127484