Without being able to go through a detail QC, this guidance document has too many technical errors and should not be published. Paid professional engineers who actually practice design in the last 10 years should review these in much more details. For the very very quick review I did, and this does not capture everything because unlike the people who have wrote this guidance document, I don't get paid to correct engineering documents provided by a government agency, here are the several errors I found. Again, someone with practicing design experience needs to re-review this document, otherwise this is going to muddy already murky waters in local agencies review.

1) Increased volumes of sheet flow section 3.305.1 and 3.305.2 incorrectly references that velocity should be checked for the 10-year storm. State code 9VAC25-870-66, ESC handbook, as well as engineering standard, and even earlier references in the guidance document specifically state that erosion is checked based on 2-yr event, NOT 10 year event. So 3.305.1.1 needs to be corrected as permissible velocities are NOT checked against the 10-year event, permissible velocities are to check for erosion which is the 2-yr event.

2-4) Three things are wrong here. A) This table of permissible velocities for sheet flow in 3.305.1.1 is said to be pulling it from Table 5-14 of the VESCH, however table 5-14 of the VESCH specifically states that these permissible velocities are for GRASS LINED CHANNELS, therefore it is incorrectly being used for sheet flow. B) The last 7 rows of the 3.305.1.1 table is NOT from Table 5-14 and is incorrectly referenced, where is the source of these last 7 rows? This goes for ALL the tables that are duplicate of this throughout the guidance document, such as also mentioned in 3.305.2, 3.302.1.C.3. C) In addition, permissible velocities in this table is limited, it’s missing more information found in the VESCH itself such as Table 5-22 for permissible velocities of unlined earthen channels of various soil types. So this is not a holistic outline of all the VESCH information and should be re-checked as I am not an expert myself. Let alone there is so many resources out there, such as VDOT Drainage Manual Appendix 7D-6, 7D-2, VDOT Drainage Manual Table 7-1, that should be acceptable as it has been practiced all over Virginia. Therefore this table should either be expansive enough to include ALL references, or caveat that more acceptable references are allowed not listed in the document.

5) The starred note below the table on 3.305.1.1 also incorrectly states high erodibility soils have k factors greater then 0.35, when in fact per VESCH it is greater then 0.36 in Appendix 6a page VI-44. 

6-7) Section 3.305.2.C to limit sheet flow stating that it is required to equate to 0.1 feet or less for the 10-year storm is grossly incorrect. A) In determining sheet flow, instructions in TR-55 Chapter 3, page 3-3 specifically states it’s for ABOUT 0.1 feet or so, NOT capped at 0.1 or less. B) In addition, TR-55 specifically bases sheet flow off the 2-year 24-hr rainfall event, NOT the 10-year event, as seen in equation 3-3 of TR 55. Velocities is continued to be calculated using the 2-yr event as further seen in Figure 3-2 example 3-1 of the TR-55 handbook. So two things are wrong here.

7) Section 3.302.1.3.A states RCP should be capped at 10 fps for velocities when the industry has accepted 18 fps to avoid abrasion. This information should be removed all together as there is no source for the 10 fps cap and should rely on manufacturer specifications or already established/accepted industry standard.

8) This guidance document is regurgitating wording and phrases pulling from other sources such as the ESC handbook, SWM handbook, state codes, National Engineer Handbook, etc etc. Instead of copy-ing and pasting the regurgitated wording and pulling tables and paragraphs from these references as people should have already read these documents, THIS guidance document should just POINT to where to find it in those documents by being a literal tour guide, hence the word guide. Instead of creating another document with repetitive wording that takes the opportunity to tweek language from its original suggestive wording to making it sound like a requirement in this text. That's not a guidance, that's simply creating new requirements. Case in point = changing sheet from flow ABOUT 0.1 feet or so in TR55, to requiring it to be CAPPED at no more then 0.1 for the incorrect year storm. I cannot go through this entire document arguing over the semantics of the language that is used. But this "guidance document" on the existing regulations that were established nearly 10 years ago is going to create more contention amongst the reviewing and design community ten years too late. Use our tax dollars appropriately and fix it. Thank you.

Thank you for your time, and apologies for any grammatical errors.

1. How were ESC practices chosen for inclusion in this document? Many common practices which would benefit from additional guidance are not included
2. Pg 11 – 2.306.B – typo “boding” should be “bonding”
3. Pg 15 – Is 3.301.E meant to remove the provision in the regulations that states “Predevelopment runoff calculations utilizing other hydrologic conditions may be utilized provided that it is demonstrated to and approved by the VSMP authority that actual site conditions warrant such considerations.”?   It’s confusing to have the direct wording of point E, and then also reference 9VAC25-870-66.E.
4. Pg 15- 3.302.1.A.1 – The language could be clearer about what to do when you hit the 1% limit at the confluence with a natural channel.  I think this is the point of all the language about “flood-prone area” under the Channel Protection section, but it could be stated more clearly.
5. Pg 19 – 3.302.4.A - Is there a preferred or recommended methodology for mapping the water surface elevation of a natural system?
6. Pg 24 - 3.305.1 – Including tables that show parameters for land slope of “Greater than 10%” seems strange.  Would you allow us to claim sheet flow discharge on a slope greater than 10%?
7. Pg 28 – 3.305.2.H – 200’ is a really long level spreader.  Constructability is questionable at this length.
8. Pg 29 – 3.305.2.M – Rock is given as an example of a material that may be used to construct level spreaders.   Will anything change about the water quality practice “Sheet Flow to Conserved Open Space” that requires a rigid lip?
9. Pg 29 – 3.306.B – No KAF is provided for the 1-year storm – how is this to be applied in situations where energy balance equation is being used?
10. Pg 29 – 3.306.B – How are we to determine what % of the drainage area is in karst?  The area that has visible surface depressions only?  Typically, the entire site will be underlain with limestone – meaning 100% is usually “karst”, so the 0-100%  DA in karst column seems odd to me.
11. Pg 30 -31 – 3.306.I – No detention practices are listed as preferred.  Even with using runoff reduction practices, there is typically still some detention needed (especially for commercial or other highly impervious developments).  Additionally, runoff reduction practices have to be lined with impermeable liners in karst per BMP Clearinghouse specs, thus reducing runoff reduction potential.  Would underground detention be the recommended detention method in karst topography?
12. Pg 33 – 4.303 – I did not locate a specific definition for “Brownfield”.
13. Pg. 37 – 4.404.A – Required total phosphorus load reduction almost never “cannot be achieved onsite through the implementation of ESD, RR, and PR practices.”   If this provision were to be strictly implemented, there would be almost no sites eligible for offsite compliance options.  Not sure if this is the intention or not.
14. Pg 38 – 5.200.B – “…should deviate from the pre-development condition by no more than plus or minus 10%” May consider adding “in total area”.
15. Pg 39 - 5.302.D – This is very impractical.  At the time of design, it is often not known what the final site soil composition will be.  Unsuitable material may be unexpectedly encountered, depth of topsoil may vary from expectations, sites may decide to initially sell their topsoil to avoid having to stockpile onsite, and then purchase topsoil later to finish the job.   Items 3 and 4 are especially impractical, as they suggest retrofitting a completed stormwater plan if the onsite HSG results come back different than expected.  I don’t see anyone doing anything other than options 1 and 2. 
16. Pg 39- 5.302 -It is unclear to me if the CN adjustment for HSG correction meant to be used for quantity compliance modeling, or are we also supposed to reflect this in the site tab of the VRRM spreadsheet as well?  I would not advocate to require HSG correction on the VRRM spreadsheet, but it does set us up for an overly complicated situation if we are using CN adjustment for runoff reduction practices.
17. Pg 39-40 – 5.302.D –Section  “D” is used twice, should be “E” on pg. 40.
18. Pg 40 – CN Adjustment table – there are several other land cover categories that I use on a regular basis.  This appears to lump many diverse land cover categories into “Open Space”.  I suppose this is just for demonstration of the selected categories.  If you are not going to cover every category, I think we could get the idea from just one category example.
19. Pg 40 – I forsee many debates and interpretations of “not directly connected to the stormwater conveyance system”.

Although many of my points in the errors I found are still noteworthy, I apologies for the aggressive tone in my previous comment. Sent an email explaining why was short on time and what unrelated personal struggles got carried into my writing. Thank you for the effort in putting this together. Please still address the corrections I had noted.

best of luck 

Prepublication copies of the Stormwater Management and Erosion and Sediment Control Design Guide were released to the public prior to publishing to the Virginia Register.  A DEQ email blast on July 20, 2022 included links to documents which DEQ stated would be published in the Virginia Register on August 1, 2022 at which point I began reviewing.  This was misleading as I have since learned that I was reviewing the wrong document and that there are language changes/additions in the August 1, 2022 published document vs. the prepublication copies from the July 20, 2022 email blast that will have significant impact to the design/development community. 

Case in point, the page numbers referenced in the comments by Lisa Koerner Perry appear to be from the prepublication document and not the official document published on the Town Hall.  If commenters are reviewing the wrong document, then DEQ will not get the proper feedback.

As commenters are reviewing the wrong document and due to differences/additions in language between prepublication copies vs. the published document and the impacts to the design/development community, DEQ should notify the public of the changes and should allow additional time for public review/comment to determine the full impacts of the changes. 

August 26, 2022

Ms. Melanie Davenport

Commonwealth of Virginia

Department of Environmental Quality

Director - Division of Water Permitting

1111 East Main Street

Richmond, VA 23219

Re:    Guidance Memo No. 22-2012

         Stormwater Management and Erosion & Sediment Control Design Guide

Dear Ms. Davenport:

As an active participant of many erosion control & stormwater permit applications within the Department’s jurisdiction, we appreciate the opportunity to review the aforementioned guidance memo and offer the following comments: 

Chapter 2.000 Erosion and Sediment Control

2.302 Temporary Sediment Trap

B. Consider eliminating wet storage, providing full availability of designed sediment storage capacity. 

2. 303. Temporary Sediment Basin

B. Consider eliminating wet storage, providing full availability of designed sediment storage capacity. 

D.1.c. Should this also state that the analysis should consider the 2-year 24-hour storm event?

D.3. Should this also state that the analysis should consider the 2-year 24-hour storm event?

F. Elaborate on definition of “structural integrity” to meet this requirement. Perhaps a check list could be provided.

Chapter 3.000 Stormwater Management – Water Quantity

3.302.2 Discharges to Restored Stormwater Conveyance Systems

In the second paragraph definition of “Flood-prone area,” include “Resource Protection Area,” similar to its inclusion of the definition section of 3.302.4.B

3.302.3 Discharges to Natural Stormwater Conveyance Systems

In the second paragraph definition of “Flood-prone area,” include “Resource Protection Area,” similar to its inclusion of the definition section of 3.302.4.B

C. Clarify whether Qforest and RVforest are for the pre- or post-development drainage area boundaries.

3.302.4 Determination of Flood-Prone Area

A. The selection of a 1-year storm event to determine flooding seems inappropriate, as most “bank-full” stream analysis contemplate a 2-year storm event.  Therefore, it would seem more appropriate to select the 10-year storm event to consider the determination of flooding.  This would be consistent with the 10-year storm selection in 3.303.1.A.

3.303 Flood Protection

This section defines the term “localized flooding.”  Could you also provide a definition “flood-prone area” to differentiate these two terms? 

Provide additional clarification/examples of what constitutes localized flooding for the purposes of evaluating an existing conveyance system. Some conveyances are more clearly defined than others (i.e. ditch vs swale).

D.1. Three cross sections within 150ft of the outfall seems excessive especially when large portions of a conveyance are on property. Such a close interval is also unlikely to yield additional useful information. Suggest that a minimum of 1 representative cross section be provided within 150ft or wherever there is a substantial change in channel geometry, roughness or slope.

3.305 Sheet Flow

3.305.1 Discharges of Sheet Flow from Pervious or Disconnected Impervious Areas

B.1/B.2 Sheet flow velocity should be evaluated using the 2-year event (consistent with Manning’s assumptions as listed in the NEH).

B.2. Can you provide clarification on selection of 0.1’ flow depth for sheet flow analysis?

3.305.2 Dishcarges of Sheet Flow from Level Spreaders

A. This seems inconsistent with the code. Sections B & C directly apply to Concentrated Flows. Section D says that increased volumes of sheet flow may be discharged through physical level spreading if they will not cause downstream flooding or erosion. If those conditions are met, then the analyses set forth by Section B and C are not required.

B. The table provided in this section references Virginia Erosion & Sediment Control Handbook, Table 5-14.  This same table is referenced in 3.305.1.B.1, however they are different tables.

E.2. Can you provide criteria for analysis of “adversely impact” to downgradient environmental features?

G. Soil Compost Amendment should not be required if no Water Quality credit is intended by use of level spreader/sheet flow area.

H. Design storm selected for this analysis is the 10-year event.  Typical level spreader design storms for many municipalities are for “first flush” runoff volumes (i.e. runoff from 1” storm), with bypass provided for larger storm event.  Consider reducing the design storm requirement to calculate the length of the level spreader.

M. Consider including treated timber as an acceptable material (Henrico and Loudon County details)

3.307 Drainage Easements

D. Please include code reference that requires easements that cover the discharge of sheet flows.

Provide a definition for “down-gradient stormwater conveyance system.”

Chapter 4.000 Stormwater Management – Water Quality

Pursuant with the guidance provided in Section 5.500 Solar Panel Arrays, additional consideration should be given to lowering post-development nutrient loading when calculating the entire solar array as disconnected impervious.  It is reasonable to deduce that the nutrient loading from the solar array, underlaid by pervious managed turf, is not the same condition as other impervious surfaces (i.e. rooftops, roads, parking lots).

4.301 New Development

D. Will this review modify the calculation in the VRRM spreadsheet?  If so, consideration should be given to the implementation period for these modifications, as they relate to projects that are currently in design and/or permitting.

Chapter 5.000 Good Engineering Design Practices

5.200 Pre- vs. Post-Development Drainage Areas/Divides

A./B. Va. Code §62.1-44.15:28 A 10 “require that VSMPs maintain after-development runoff rate of flow and characteristics that replicate, as nearly as practicable, the existing predevelopment runoff characteristics and site hydrology.”  Item B exceeds the regulatory requirement, by introducing a finite amount of change to a specific design parameter, which the current regulation does not contemplate.  It appears as though the regulatory language already provides sufficient clarity in regard to equalizing post-development runoff to pre-development conditions.

5.301 Pre-Development Curve Number Selection

D. Provide clarification that existing Agricultural land would meet the definition of “previously disturbed soils,” as they are “native soil profiles that have been mixed or removed,” thereby allowing for the prescribed adjustment of HSG by at least one factor.

5.302 Post-Development Curve Number Selection

D. This section defines that “disturbed soils,” which is indicative of all areas within the Limits of Disturbance (LoD), will need to meet the criteria of this section.  In previous discussions with VDEQ reviewers, these criteria only applied to areas of “fill” in the proposed design. Can you provide clarification of why this would apply to areas of “cut” and/or areas where the existing grade is not modified (i.e., coastal plain sites)? Following construction, stripped and stockpiled topsoil is applied to cut areas and ungraded areas are decompacted and surface roughened prior to application of temporary/permanent stabilization.

D. Consideration should be given to the implementation period for these modifications, as they relate to projects that are currently in design and/or permitting. It will have profound consequences to developable acreage.

E. Correct the last section to be item “E.”

E. The inclusion of “Forest Cover (adjusted)” is likely not necessary, due to the definition of “disturbed soils” would constitute the removal of trees.

E. Chapter 9, Part 630, NRCS National Engineering Handbook Table 9-5 defines Open space to include lawns.  It is unclear what differentiates Open Space from Managed Turf.  Please include definitions of the categories, so it is clear to designers for their selection of CN.

5.500 Solar Panel Arrays

D. We have designed and built hundreds of utility scale solar projects in North Carolina and Virginia over the past decade and have not encountered rain-sensing technology.  Please provide any industry contacts who manufacture and integrate this product offering.

Additionally, we offer the following feedback/considerations for this guideline:

• For single-axis tracker systems, typical rotations are 52° from horizontal (up to a maximum of 60°).  Provide clarification that this meets guidance to “rotate to a vertical position”
• In the case where “vertical position” is achieved during applicable rain events, please clarify that all structural support elements (posts, torque tube, etc) will still be considered impervious surfaces even though they are located beneath the modules which would effectively be pervious.
• Recommend providing clarification on the minimum interval to deploy rain-sensing technology due to large variability of weather patterns over the footprint of utility scale projects.  It is likely that only portions of the site would have rainfall to meet the deployment criteria.
• Single-axis tracker systems have variable stow characteristics (depending on the manufacturer) during wind and/or snow events.  Most elevated wind events (typically triggered by ≥35 mph, depending on manufacturer) are accompanied by rainfall.  To prevent torsional galloping of the structure, many manufactures stow at 0° (horizontal) to 30° to lower the profile of the structure.  Therefore, it may be difficult for many systems to comply with this regulation during high wind events.
• Most manufacturers now offer various software algorithms to improve energy production on cloudy days (diffused light).  These strategies can tilt all of the trackers in various directions, depending on sensors deployed to monitor light levels.  The introduction of rain-sensing technology would most likely negate the effectiveness of these technologies.
• Single-axis trackers move very slowly, mostly dictated by the speed at which they need to rotate to track the sun throughout the day.  Frequent movement of the tracker due to potentially intermittent showers on cloudy days would significantly disrupt overall energy production, lowering the overall availability of the energy from the plant

Thanks for your time and consideration.

Sincerely,

Brent T. Niemann, PE

Director of Civil Engineering

Strata Clean Energy    

Please source where in NEH or other non-VA DEQ standard engineering hydrologic documents that require to adjust the HSG by atleast 1 factor when disturbing soils or working with disturbed soils as described in GM 5.301.D.1 & 5.302.D.2.

It is not found in the state regulations. The state regulations specifically state in 9VAC25-870-66.E "all pervious lands on the site shall be assumed to be in good hydrologic conditions in accordance with the US Dept of Ag NRCS standards, regardless of conditions existing at the time of computations."  In otherwords, despite how disturbed the conditions are, it does not give leeway for predevelopment to downgrade the runoff CN to poor. Post development may use "poor" pervious conditions due to disturbance if engineer judges so.

NRCS has hydrologic conditions already assigned for poor and good conditions stating that "Poor=Factors impair infiltration and tend to increase runoff; Good= Factors encourage average and better than average infiltration and tend to decrease runoff" It seems redundant to re-create NEH guidance and state that if lands are now disturbed (which is equivalent to impairing the infiltration ability of the soil using conditions of Poor) that instead of using historic standard practices (and whats used all over the country), that we should negate NEH and come up with new rules for hydrology. If new rules outside of the State Regulations are being created please provide the actual science/studies that supports this hydrologic adjustment (similarly to how NEH has done) for public commenting.

9VAC25-870-72.C also specifically states "NRCS OR other standard hydrologic & hydraulic methods shall be used..." This adjustment described in 5.301.D.1 & 5.302.D.2 is not standard with NRCS nor Rational Method, outside of the draft VA SWM HB please provide where is it standard in other hydrologic methods? If this is not actually standard, VA DEQ guidance to adjust disturbed soils is then going against State Regulations and creating new requirements outside the regulatory forum.

Also to note-Shouldn't the energy balance equation with the improvement factor adjustment already take into consider all these nuances with post development soils mixing?

Melanie D. Davenport

Sent via: Melanie.Davenport@DEQ.Virginia.gov

Re: Guidance Memo No 22-2012

Dear Ms. Davenport,

We have received the Guidance Memo referenced above and have taken the opportunity to review and provide comment. We appreciate DEQ’s efforts in creating a document that will help the development community better understand the intent behind Virginia’s Stormwater Management Regulations. We understand many other firms and organizations have taken the time to review as well; therefore, we expect DEQ will take comments from the design community into serious consideration as this community applies the regulations on a daily basis. It is the design community’s experiences that find unintended consequences and situations where a set rule will not be applicable in all situations.

We hope the comments DEQ receives will assist in a revision to the Guidance Memo such that another revision may be posted for public comment until there is a final version that addresses all comments or explanations have been publicized to understand why comments are not addressed.

In an effort to understand our firms’ experiences, we are a team of Professional Engineers, and Stormwater Reviewers who have worked in West Virginia, Tennessee, North Carolina, and South Carolina. We have practiced Stormwater Design prior to the inception of the VSMP regulations.  We believe that of the five states we have worked, Virginia has the most complex set of Stormwater regulations. With this being said, a Guidance like this is helpful assuming it represents the VSMP regulation correctly.

Our firm offers the following comments:

Guidance Section 2.302 D. (Page 9) Runoff coefficients or curve numbers used in runoff computations should correspond to a bare earth condition. See Section 5.303 herein.

Guidance Section 2.303 F. (Page 11) Runoff coefficients or curve numbers used in runoff computations should correspond to a bare earth condition. See Minimum Standard #6, 9VAC25-840-40 6, and Section 5.303 herein. 

Comment:

State Code 9VAC25-840-40 (6b) states, “Runoff coefficients used in runoff calculations shall correspond to a bare earth condition or those conditions expected to exist while the sediment basin is utilized.”

We believe the State Code is more applicable as there are situations where a drainage area to a sediment trap or basin may include offsite drainage areas that are not permitted to be disturbed and those areas shall not be required to use a runoff coefficient or curve number for bare earth conditions. Eliminating the “or those conditions expected to exist while the sediment basin is utilized” portion of the State Code in the Guidance creates a document conflicting with a State Code.

Guidance Section 3.30.1 (C) (3a) (Page 16) Permissible (non-erosive) velocities.  Reinforced Concrete Pipe (RCP). Post-development stormwater velocities should be less than or equal to 10 feet per second (ft/sec). 

Comment: 

There are many types of pipes used for drainage, i.e. CMP, HDPE, RCP, etc. Each type of product has special manufactured processes that may affect the allowed velocity in the pipe. For example, this section only references Reinforced Concrete Pipe, and there are different types and classes of Reinforced Concrete Pipe that may have different maximum velocities recognized by the manufacturer. Additionally, the American Concrete Pipe Association states “At velocities up to 40 feet per second, the severity of velocity-abrasion effects depends upon the characteristics of the bed load.” With this being said, there are several factors that will affect maximum velocity and the designer shall have to prove the material and bed load supports that velocity. We suggest permissible velocities over 10fps shall be allowed provided the designer can provide documentation from an industry association or manufacturer supporting the proposed velocity. We suggest this should be the same for man made channel linings of which this Guidance does not address.

Guidance Section 3.302.3 Discharges to Natural Stormwater Conveyance Systems.  (Page 18) A manmade lake or reservoir not created for the purpose of managing post-development stormwater should be considered a natural stormwater conveyance system. 

Comment:

Our firm has provided DEQ several statements regarding this interpretation. We would ask you refer to letters we have written to Erin Belt over the last year. We feel strongly that a lake or reservoir created by a manmade dam is a stormwater conveyance system created by man, and managed by man; therefore, meets the definition of manmade stormwater conveyance system. The guidance in its current form conflicts with State Code 9VAC25-870-10 that states,

“Stormwater conveyance system" means a combination of drainage components that are used to convey stormwater discharge, either within or downstream of the land-disturbing activity. This includes:

1. "Manmade stormwater conveyance system" means a pipe, ditch, vegetated swale, or other stormwater conveyance system constructed by man except for restored stormwater conveyance systems;

2. "Natural stormwater conveyance system" means the main channel of a natural stream and the flood-prone area adjacent to the main channel; or

3. "Restored stormwater conveyance system" means a stormwater conveyance system that has been designed and constructed using natural channel design concepts. Restored stormwater conveyance systems include the main channel and the flood-prone area adjacent to the main channel.”

A manmade lake or reservoir that conveys stormwater meets the portion of manmade stormwater conveyance system definition in the State Code that states, “other stormwater conveyance system constructed by man.”

We have experience designing developments on Smith Mountain Lake and more recently Lake Anna. There are discharges that have been designed, permitted, and constructed that met manmade channel protection criteria or sheet flow criteria. We have monitored those situations and have experienced no degradation to those lakes at these points of discharge. Classifying these discharges to natural stormwater water conveyance channels will require best management practices to meet the energy balance method. This will create maintenance burdens that are not necessary as these best management practices will not provide any more protections to downstream properties. Considering these lakes outflows are managed by man, and the sizes of the watersheds to these lakes are so large, there is no benefit to classify these lakes as natural stormwater conveyance systems. We suggest eliminating this sentence from the definition as it does not match state code and conflicts with the definition of manmade stormwater conveyance system.

Guidance Section 3.302.5 (page 20) Channel Protection Analysis Point. Where applicable, the allowable peak flow rate should be based on the area of the site that drains to the point of discharge in the pre-developed condition.

Comment:

In the cases as described herein on lakes, the predeveloped condition at the point of discharge is most often sheet flow for a small drainage area. Any development creates concentrated runoff and can only be discharged to the lake. Meeting the allowable peak flow rate is typically impracticable as the energy balance method will define an allowable peak flow rate of zero. Consideration shall be given to situations where this is not feasible.

Guidance Section 3.305 Sheet Flow (Page 24)

A. Piped or channelized stormwater runoff converted to sheet flow prior to discharge should
comply with 9VAC25-870-66 B (see Section 3.302 herein) and 9VAC25-870-66 C (see
Section 3.303 herein) or “Safe Harbor” (see Section 3.304 herein).

Comment:

VA State Code 9VAC25-870-66 D states,

“Increased volumes of sheet flow that will cause or contribute to erosion, sedimentation, or flooding of down gradient properties or resources shall be diverted to a stormwater management facility or a stormwater conveyance system that conveys the runoff without causing down-gradient erosion, sedimentation, or flooding.”

In cases where stormwater management can create a sheet flow condition from a piped or channelized flow that does not cause down gradient erosion, sedimentation, or flooding, we believe the State Code allows a solution that doesn’t require meeting 9VAC25-870-66B or 9VAC25-870-66C. A specific example would be discharging to a lake that has a watershed so large the quantity of runoff will not impact the downstream properties. Installing a level spreading device that will create a sheet flow condition that does not erode the shorelines, nor carries sedimentation to the lake, nor increases the lakes flood levels meets the State Code. We suggest providing language that addresses these situations, or simply reference Sate Code rather than put more restrictive requirements to what the State Code allows.

Guidance Section 3.305.2 Discharges of sheet flow from level spreaders.
Page 27 – B. Virginia Erosion and Sediment Control Handbook Table 5-14

Comment:

The table in this section does not match VESCH Table 5-14, Velocities have been reduced. The same table is referenced in Section 3.305.1 (B) with the correct values from VAESCH Table 5-14. It is recommended to revise the table.

Page 29 - G. The area of sheet flow should be located outside the limits of clearing and grading and be protected by erosion and sediment controls, or the area should undergo soil restoration via full implementation of DEQ Stormwater Design Specification No. 4 (Soil Compost Amendment) immediately prior to establishing permanent stabilization. 

Comment:

In general, we believe this is good practice; however, in a situation where sheet flow has been created to discharge to a lake regulated by the Federal Energy Regulatory Commission which enforces shoreline management regulations that require shoreline stabilization, this could not be met. The limits of disturbance would be required to include the shoreline stabilization measures. We suggest language to allow this situation to occur.  

Guidance  Section 3.307 Drainage Easements (Page 33)  D. Offsite discharges of sheet flow from a level spreader, with the exception of those discharges meeting the requirements of Safe Harbor (Section 3.304) herein, should be encompassed with a drainage easement. The minimum width of the easement should be the length of the level spreader plus 5 feet on each side. The minimum length of the easement should be the distance of the sheet flow path to the down-gradient stormwater conveyance system. 

Comment:

In general, we believe this is good practice; however, in a situation where sheet flow has been created to discharge to a lake regulated by the Federal Energy Regulatory Commission which enforces shoreline management regulations that require shoreline stabilization, this could not be met. The owner of the lake will not give easements as their permitting process to install shoreline stabilization covers the necessary requirements an easement would grant. We suggest language that will allow permits in these situations to substitute as easements.

Guidance Section 4.404 STEP 4: Offsite compliance options. (Page 39)
A. Design professionals should investigate the use of offsite compliance options if the
required total phosphorus load cannot be achieved onsite through the implementation of
ESD, RR, and PR practices 

Comment:

We believe this is more restrictive than VSMP regulations 9VAC25-870-69 which provides specific instances were offsite compliance have to be allowed therefore Section 4.404 (A) conflicts with State Code and Section 4.404(B) of the Guidance.

Guidance Section 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%. 

Comment:

We recently worked on a project where the natural low discharged to a location that was problematic. The only solution was designing a best management practice to meet Safe Harbor rules with a level spreader to create the sheet flow condition that represented the pre-developed condition. The locality did not want this to occur due to problems downstream and requested re-directing runoff to a manmade channel piped offsite to a location that avoided the natural downstream issue. Best Management Practices were designed to re-direct the post developed runoff to another location meeting VSMP regulations creating a better situation for the downstream property and resolving the issue. This section of the guidance will not allow this solution.

Additionally, it can be very difficult to match pre-development drainage divides. The VSMP regulations require pre-developed conditions to be analyzed to define allowable conditions for the post developed condition; therefore, if drainage divides must change the pre-developed condition analysis will require additional best management practices due to the increase in post developed drainage area. We believe defining a limit on drainage area deviation will create hardships that may not be overcome in any type of design.

We recommend eliminating this Section of the Guidance.  

Furthermore, we believe DEQ shall give more time for public review as we received two different copies of the Guidance Memo. One copy was received two different ways from the Virginia Tech BMP Clearinghouse and from DEQ on behalf of the Director, Mike Rolband, both by email. These copies were stamped DRAFT. It was not until August 18th that we recognized what was posted on Town Hall website for public comment was different than what we received in emails from DEQ and Virginia Tech. We have also noted that the public has commented on the DRAFT copy. We can only assume they are unaware of the difference. It shall also be noted both the DRAFT copy and the copy on Town Hall website are dated July 1^st, 2022. Unfortunately, we believe the publication of the document has been misleading and DEQ shall ensure everyone knows the difference between the two copies.  

We appreciate the opportunity to provide comment and trust DEQ will take all comments under consideration when determining how to finalize the guidance.

Respectfully,

Sheldon R. Bower, PE

Parker Design Group, Inc

We have reviewed the guidance document and offer the following comments:

1. The guidance document states: “A majority of the information contained herein is a compilation of existing requirements already in place.  This guidance document will serve as a central reference for these items.” The guidance document paraphrases or slightly changes wording of multiple regulatory texts, which creates ambiguity and should be avoided.  This guidance document creates conflicts in language between regulatory documents, which confuses the review process.  This means design professionals will be required to refer the VAC, reference materials cited in 1.300, and the guidance document to attempt to interpret the intent of DEQ.  This is not acceptable. This document as written will provide more confusion than clarity.

If no additional clarity is being provided by paraphrasing or slightly changes wording of regulatory text, then that section should not be included in the guidance document.

In cases where the guidance document is providing new interpretation, it should be made clear that the information is new. 

2. Section 3.301.A-This section directly amends regulatory language to now include the 1.5-year (Safe Harbor) and 100-year, 24-hour storms as the prescribed design year storms.  The guidance document should be revised to include regulatory references for DEQ authority to regulate the 1.5-year (Safe Harbor) and 100-year, 24-hour storms and in what specific situations.  See below for additional comments on the 1.5-year (Safe Harbor) provisions.
3. Section 3.302.1 A-B – It is unclear what clarity DEQ is offering by rewording and reordering the regulatory text of section 9VAC25-870-66.B.1.  See comment 1. 

This section would be much more effective by presenting the regulatory options in flowchart format with no rewording or paraphrasing of regulatory text, or only providing statements on what clarity they are adding to the regulation, such as the emphasis of the word “OR”.

4. Section 3.302.1.C.2 & 3.303.1.D & 3.303.2.C–A definition for “field survey” should be provided. Does this require a licensed land surveyor or is an engineer’s field measurements adequate.
5. Section 3.302.1.C.3 –Many of these permissible velocities are not in line with industry standard and incorrectly source other state sources.  This section should cite the appropriate regulatory references.
6. Section 3.302.2 A-B –It is unclear what clarity DEQ is offering by rewording and reordering the regulatory text of section 9VAC25-870-66.B.2.  See comment 1. 

This section would be much more effective by presenting the regulatory options in flowchart format with no rewording or paraphrasing of regulatory text, or only providing statements on what clarity they are adding to the regulation, such as the emphasis of the word “OR”.

7. Section 3.302.3.A –It is unclear what clarity DEQ is offering by rewording and reordering the regulatory text of section 9VAC25-870-66.B.3.a. See comment 1. 

This section would be much more effective by presenting the regulatory options in flowchart format with no rewording or paraphrasing of regulatory text, or only providing statements on what clarity they are adding to the regulation, such as the emphasis of the word “OR”. 

8. Section 3.302.3.B & C.- In the VAC, the word “NOR” is utilized between these 2 bullet points.  We request that the word “NOR” be defined in this guidance document.  We have had confusion with local jurisdictions about the implementation of these sections and whether they apply as an “either or” or an “and”. This has resulted in us being held to an allowable release rate from an existing pond to below the forested condition.   
9. Section 3.302.4 – This section redefines the definition of “flood prone” area from the VSMP regulations and intends to limit the definition to flooding of the 1-year storm from a natural conveyance, with only case-by-case approval for the other areas defined in the regulations.  We object to rewriting of a regulation outside a regulatory process.  The VSMP regulation clearly defines flood prone areas to include, but not limited to floodplain, flood fringe, wetlands, riparian buffers, or other areas adjacent to the main channel.  The VSMP regulation specifically grants authority to use these areas and should not be evaluated by DEQ on a case-by-case basis.
10. Section 3.303.1 A – While not within the scope of this guidance document, we would like to see this section be reconsidered at the next regulatory re-write/review period.  In our opinion, the word “OR” should be added at the end of 3.303.1.A. allowing applicants to provide “stormwater detention or downstream stormwater conveyance system improvements” according to 9VAV25-870-66.C.2 eliminating the need for a costly flooding analysis, to which the solution would be detention.
11. Section 3.304 – Safe Harbor – We believe the inclusion of this as an additional requirement for land disturbing activities is a misinterpretation of Section 62.1-44.15:28.A.10 of the State Water Control Law, as well as an inappropriate carry over from the requirement of section 19 of 9VAC25-840-19 (MS-19).  The State Water Control Law section states that land-disturbing activities that meet the three (3) conditions of this section are then “shall be exempt from any flow rate capacity and velocity requirements for natural or man-made channels as defined in the regulations promulgated pursuant to this section or any ordinances adopted pursuant…”.  Therefore, this reads as an alternative SWM compliance approach, and not something required in addition to the VSMP regulations.  In addition, section 9VAC25-840-19.n of MS-19 clearly states that compliance with the VSMP regulations satisfies all requirements of subdivision 19.  Therefore, this section should be stricken from the guidance memo. 
12. Section 3.305.1

1. We strongly object to the use of the 10-year storm for evaluation of erosive velocities.  The VSMP regulations themselves evaluate erosion for the 2-year storm. Industry standards also have established precedent for 2-year erosion analysis.  This section should be amended to require evaluation of erosive velocities from the 2-year storm only.
2. We object to the use of the 0.1 feet for the allowable 10-year depth.  This appears to draw from guidance in TR-55.  TR-55 states “shallow flow depths of about 0.1 foot or so”.  In addition, this section of TR-55 is for use in time of concentration, which is for the 2-year storm.  Therefore, I do not think this is an appropriate regulatory reference for establishing this threshold.
3. This section redefines the standards for evaluating increased volumes of sheetflow from “cause or contribute to erosion, sedimentation, or flooding on down-gradient properties or resources” to “adversely impact down-gradient property or environmental features”.  I think this is an inappropriate re-writing of the regulations.
4. This section paraphrases sections from the manmade, restored, and natural channel sections in a manner that is not clear.  It appears as if all bullets a-e are required, when it really means “or”.  This section should be reworded to clarify when bullets c-e would be applicable.

13. Section 3.305.2 – We have the same comments for this section as Section 3.305.1.  In addition, we have the following comments on the level spreader:

1. The sizing of level spreaders has been redefined to be based on the 10-year Q.  This is in direct contradiction to the sizing criteria established in the DEQ Specification #2.  The DEQ specification states that the sizing of level spreaders is based on the water quality design peak flow rate, which is the 1” storm.
2. The allowable level spreader lengths are redefined as 10-200 feet.  This is in contradiction with DEQ Spec #2, which states level spreader lengths are 13-130 feet.
3. The sizing methodology equation is in direct contradiction to the sizing methodology established in DEQ Spec #2, which is a function of LF of level spreader per cfs.
4. DEQ Spec #2 allows for concrete, wood, pre-fabricated metal, or rigid non-erodible material.  Is this section intending to strike the use of wood and pre-fabricated metal?

14. Section 3.307 – Please provide the code reference that gives DEQ the regulatory authority to dictate drainage easements required to be recorded with localities.  We are not aware that DEQ has this regulatory authority.  The following is offered for consideration.

1. The storm drainage easement widths are in direct contradiction with a lot of local municipalities codes.
2. The provision for easements on sheetflow areas to the down-gradient stormwater conveyance systems is an overreach and misalignment with the line with the intent of these regulations.  This would make development in many locations completely infeasible for incidental sheetflow areas, even in instances where there is a reduction in sheetflow volume, to obtain offsite easements from adjacent property owners.  In addition, this is not consistent with how any Northern Virginia municipality interprets and enforces the sheetflow provisions in the VSMP regulations.

15. Section 4.301.D & 4.302.H – This statement says the phosphorus load design criteria is “subject to change”.  DEQ should clarify whether they intend for these changes to go through a regulatory revision process.  It is unclear how DEQ could change the water quality design standards without further regulatory action.
16. Sections 4.301 & 4.302– It is unclear what clarity DEQ is offering by rewording and reordering the regulatory text of section 9VAC25-870-63.  See comment 1. 

This section would be much more effective by presenting the regulatory options in flowchart format with no rewording or paraphrasing of regulatory text, or only providing statements on what clarity they are adding to the regulation, such as the emphasis of the word “OR”.

17. Sections 4.303 and 4.304 – These sections add new classifications of land use “brownfield” and “reclaimed coal mine” that are not defined. Comprehensive definitions of these land uses should be provided. Why is DEQ giving special provisions to these land uses?  Justification should be provided in this document.
18. Section 4.305 – This section adds additional criteria to regulate water quality by the drainage to each karst feature.  This is a major change to the regulations, and this type of change appears like it should go through a regulatory action, not a guidance document.  This guidance document is creating new regulation, not providing clarity to the existing regulation.
19. Section 4.404 – This appears to be directing designers on how to design, not providing clarity on existing regulatory requirements.  This better belongs in a design manual, not a guidance document.
20. Section 5.000 - Does DEQ plan to enforce “good engineering design practices”?  If so, how?  Again, this feels like it belongs in a design manual, not a guidance document on regulations.
21. Section 5.200 – What is the source of a good engineering practice of post-development drainage areas not deviating more than 10% from the pre-development drainage areas?   
22. Section 5.301.D & 5.302.D – Additional sources should be provided to justify the manual adjustment of previously disturbed and proposed disturbed soils. This process will significantly overcomplicate the stormwater compliance for sites.  It is not clear how this is defined as “good engineering design practice” without additional sources or guidance from other reputable entities that require these changes. In addition, further guidance would be required for how to input this into the VRRM spreadsheet, as changes in total areas of soil types is not permitted by the spreadsheet.
23. Section 5.600 – Further clarification from DEQ is required to determine how they plan to administer these “good engineering design practices”.  An acid sulfate soils screening in consultation with VT or other qualified professional is an extreme undertaking for development projects, both resources, time, and money.  If the mitigation for high acid sulfate soils does not include the design of stormwater management BMPs, it is unclear how this belongs under DEQ regulation of the VSMP regulations. 
24. Section 6.000 – This same checklist is included in another draft guidance memo.  It seems confusing to have the same checklist memo published in 2 separate memos.  One of them should be removed.
25. Due to the nature of these comments, we object to the publishing of this guidance document on September 1, 2022 until all comments can be reviewed and addressed.

Signed: Kelsey Ryan, PE, Steve Pandish, PE, and MacKenzie Bauman, PE (Gordon)

August 30, 2022

Dear Ms. Davenport and Mr. Hammond:

Our firm represents American Land Holdings, LLC ("American Land"), a developer and parent company for multiple lakefront and waterfront vacation home developments on the East coast. Two of American Land's premier projects under development are located in Virginia: Rock Island Landing and Compass Cove, both lakefront on Lake Anna in Louisa County. American Land's affiliate also in 201 7-19 successfully completed and sold Kennedy Shores with lake-front residential lots on the banks of Smith Mountain Lake in Franklin County.

The owner of American Land also owns Spring Creek Land Development, LLC ("Spring Creek Development"). Spring Creek Development has years of experience as a developer of high end residential lots, and its signature project is the 980-acre residential and golf resort community of Spring Creek, located in Louisa County. Spring Creek is a primary economic driver of the County's growth and has, over the last several years, been the underpinning of the growth area in the Zion Crossroads District. The projects of these two developers provide critical tax revenues for the County.

American Land generally applauds the Virginia Department of Environmental Quality's ("DEQ's) efforts to provide guidance to· standardize project design and review in the Commonwealth. Such guidance is needed and will help reduce the inconsistent reviews of projects that developers have been experiencing across the state. However, one sentence in the guidance unnecessarily and adversely affects the development of lakefront lots on Lake A1ma and Smith Mountain Lake without any environmental benefit. The draft guidance directs that waterbodies such as these two man-made lakes must be considered natural stormwater conveyance systems instead of man-made systems. [DEQ, Guidance Memo No. 22-2012, Stormwater Management and Erosion & Sediment Control Design Guide, at 18 (stating: "A manmade lake or reservoir not created for the purpose of managing post-development stormwater should be considered a natural stormwater conveyance system.")]

The regulation defines "manmade stormwater conveyance system" as "a pipe, ditch, vegetated swale, or other stormwater conveyance system constructed by man except for restored stormwater conveyance systems." 9 VAC 25-870-10.  On the other hand, a "natural stormwater conveyance system" is defined as "the main channel of a natural stream and the flood-prone area adjacent to the main channel." Id. The image that presents for the latter is of a creek or stream with its adjacent floodplain. Lake Anna and Smith Mountain Lake are not natural streams with adjacent floodplains. Instead they are flooded valleys, controlled by manmade dams, with lake levels manipulated according to power plant needs rather than fluctuating in the way of natural lakes. There is very little that is "natural" about these two lakes and they clearly do not fit within the natural stormwater conveyance system definition. They are, however, "other stormwater conveyances" under the definition of a manmade stormwater conveyance system.

Our client's concern is not water quality treatment for lakefront developments, but rather water quantity for projects specifically on Lake Anna and Smith Mountain Lake. By identifying these lakes as natural stormwater conveyance systems, DEQ guidance demands the use of the energy balance method to address water quantity. The method is designed to provide that pre- and post-development runoff into a natural stormwater conveyance system is the same - primarily to avoid erosion and degradation due to full bank events of natural streams. But concentrated discharges at Lake Anna and Smith Mountain Lake are not to natural streams with banks to protect. Designing and implementing a solution to meet energy balance requirement is not more beneficial to the shorelines of these lakes than meeting DEQ's requirements for discharges to manmade stormwater conveyance systems.

Both of these lakes have very large watersheds and the volume of water discharged in the 2-year, 24-hour storm calculated for a project assuming the lakes are manmade systems is miniscule compared to the volume of water discharging to the lake from all other sources in the watershed during that same 2-year, 24-hour storm. And when the discharge point from the storm water system is close to the lake itself or water is discharged over a level spreader, the volume of water discharging to the lake does not create an erosion issue for the lake or any natural channel.

Applying the energy balance method to concentrated discharge points on Lake Anna and Smith Mountain Lake often results in zero-discharge requirements because of the small contributing drainage area at each point and sheet flow conditions at the shoreline. That makes the development of such lots economically impossible. By this requirement, DEQ effectively halts the development of waterfront lots on the state's lakes, whether large or small.

Lake Anna and Smith Mountain Lake are unique in their size in the Commonwealth and in their use for power plant management. Because of the reasons described above, our client strongly recommends that DEQ guidance be changed so that Lake Anna and Smith Mountain Lake are considered manmade stormwater conveyance systems.

We also noticed that DEQ sent out a pre-publication version of the guidance to multiple individuals and Certified Stormwater Reviewers on the DEQ mailing list. The pre-publication version of the guidance did not include the sentence identified in Footnote 1 above about how to consider lakes like Lake Anna and Smith Mountain Lake. We have already noticed individuals providing comments on the pre-publication version of the guidance rather than the version that was published in the Virginia Register. While we know that the published version is the version that everyone should review, the fact that DEQ sent out the pre-publication version under Michael Rolband's signature makes it likely that many people will not see the language that was added to the final publication version. We recommend that DEQ notify all individuals on its mailing lists who received the prepublication version the guidance and that the agency provide an additional 30-day comment period to ensure that it is receiving comments on the correct document version.

Our client is available to discuss these comments at your convenience.

Respectfully submitted,

McGuireWoods LLP

Heather N. Stevenson

In general, this document has many omissions or word changes form regulatory text, incorrect references, or incorrect data that generates much more confusion than it does clarity. 

2.302 Temporary Sediment Trap

D. Runoff coefficients or curve numbers used in runoff computations should correspond to a
bare earth condition. See Section 5.303 herein. This language does not apply to Sediment Traps per 9VAC25-840-40 #6. Recommend removal of this language as it pertains to Sediment Traps.

2.303 Temporary Sediment Basin

F. Runoff coefficients or curve numbers used in runoff computations should correspond to a bare earth condition. See Minimum Standard #6, 9VAC25-840-40 6, and Section 5.303 herein.  This does not meet current regulation as written as it omits language from MS#6.  MS#6 also allows for those conditions expected to exist while the sediment basin is utilized.  Please include this language as allowed by regulation as there are circumstances where the entire drainage area to a basin may not be disturbed.

3.301 DESIGN STORMS AND HYDROLOGIC METHODS

C. The Natural Resources Conservation Service (NRCS) synthetic 24-hour rainfall distribution models, including but not limited to, NRCS Technical Release 55 and NRCS Technical Release 20, should be used to perform the water quantity design computations herein. Hydrologic and hydraulic methods developed by the U.S. Army Corps of Engineers may also be used. See 9VAC25-870-72 C.  This omits language from the VSMP regulation and therefore does not meet current regulation as written.  See 9VAC25-870-72 C.  Regulation also allows for other standard hydrologic and hydraulic methods.  Please include this language as allowed by regulation.

3.302.1 DISCHARGES TO MANMADE STORMWATER CONVEYANCE SYSTEMS

C. Channel Protection Computations.

3. Permissible (non-erosive) velocities Please provide a source for this standard for RCP.  This is not practical and may preclude the use of RCP.  What about other pipe types?  What about other open channel linings?

3.302.3 DISCHARGES TO NATURAL STORMWATER CONVEYANCE SYSTEMS
“Natural stormwater conveyance system” means the main channel of a natural stream and the
flood-prone area adjacent to the main channel. This includes any natural or perennial or
intermittent streams, unimproved ephemeral channels, wetlands, or swales. A manmade lake or
reservoir not created for the purpose of managing post-development stormwater should be
considered a natural stormwater conveyance system. 

This does not meet current VSMP regulation.  Please see 9VAC25-870-10. Definitions. Every other definition provided in this guidance document appears to be from the VSMP regulation but this one has been added to as highlighted above.  DEQ cannot arbitrarily change or add to the definition of items defined in the VSMP regulation in a guidance document. In addition, VSMP regulation clearly defines “manmade” and the technical criteria that apply. 

3.302.4 DETERMINATION OF FLOOD-PRONE AREA

A.The limits of a natural stormwater conveyance system’s flood-prone area should be
determined by mapping the water surface elevation associated with the pre-development
1-year 24-hour storm event. Computations supporting the natural system’s 1-year 24-
hour water surface elevation should be provided with the plan.

B. DEQ may consider discharges to other areas adjacent to main channel (e.g., mapped
Federal Emergency Management Agency (FEMA) floodplain, FEMA floodway, FEMA
floodway fringe, wetlands, riparian buffers, Resource Protection Areas) on a case-by-case
basis. 

This section appears to be attempting to redefine a “flood prone area” from VSMP Regulation.  As the definition of a “flood prone area” includes the items in B.  DEQ cannot consider these on a case by case basis as it goes against VSMP regulation.

3.305.1 DISCHARGES OF SHEET FLOW FROM PERVIOUS OR DISCONNECTED
IMPERVIOUS AREAS

A&B1 - 10-yr 24 storm velocity requirement – This should be 2-yr velocity. 10-yr is against VSMP regulation as even the VSMP regulation evaluates erosion for the 2-yr storm.  In addition, See 9VAC25-870-72 C which lists the required methods to conduct the analysis in VSMP regulation.  Standard methodology would be to evaluate velocities for the 2-yr storm.

B2 - 10-yr 24 storm depth of sheet flow of 0.1’ requirement. - See 9VAC25-870-72 C which lists the required methods to conduct the analysis in VSMP regulation.  The 0.1’ is from reference manuals with regards to Time of concentration section which is for the 2-yr storm from the NEH or TR-55.  Applying the 0.1’ depth requirement to the 10-yr storm would not be a standard hydrologic or hydraulic method and would be against VSMP regulation.  Suggest changing this to the 2-yr storm.

3.305.2 DISCHARGES OF SHEET FLOW FROM LEVEL SPREADERS
A. Piped or channelized stormwater runoff converted to sheet flow prior to discharge should
comply with 9VAC25-870-66 B (see Section 3.302 herein) and 9VAC25-870-66 C (see
Section 3.303 herein) or “Safe Harbor” (see Section 3.304 herein).  This doesn’t not meet VSMP regulation.  9VAC25-870-66D clearly allows sheet flow from the “…physical spreading of concentrated flow through level spreaders…” that do not have to meet the requirements stated in A. This should be removed from this section.

B - 10-yr 24 storm velocity requirement – Same as above in 3.305.1 In addition, the values in this table are incorrect and do not match the same table and reference elsewhere in the document.

C. 10-yr 24 storm depth of sheet flow of 0.1’ requirement – Same as above.

Additionally, there are several conflicts with DEQ BMP Specifications on the clearinghouse that need to be resolved.

4.404 STEP 4: OFFSITE COMPLIANCE OPTIONS
A. Design professionals should investigate the use of offsite compliance options if the
required total phosphorus load cannot be achieved onsite through the implementation of
ESD, RR, and PR practices.  This appears to ignore the fact that VSMP regulation lists specific instances where offsite compliance options shall be allowed.  A strict interpretation of this would be against regulation.

5.200 PRE- VS. POST-DEVELOPMENT DRAINAGE AREAS / DIVIDES
A. Post-development drainage areas and drainage divides should replicate, as nearly as
practicable, the pre-development drainage areas and drainage divides. See Va. Code §
62.1-44.15:28 A 10. 
B. Post-development drainage areas should deviate from the pre-development condition by
no more than plus or minus 10%. 

Where is the source for 10%?  This appears to be arbitrary and will be an unobtainable and impracticable limit in a lot of cases. 

This entire section should be removed as it does not meet regulation.  The language in A is not the language from the referenced code.  The code states “… runoff rate of flow and characteristics that replicate, as nearly as practicable, the existing predevelopment runoff characteristics and site hydrology…”.  Runoff characteristics and site hydrology encompass so much more than just drainage areas/divides.  Attempting to limit one specific parameter is a complete misinterpretation of the referenced code.

August 31, 2022

Ms. Melanie Davenport

Commonwealth of Virginia

Department of Environmental Quality

Director - Division of Water Permitting

1111 East Main Street

Richmond, VA 23219

Melanie.davenport@deq.virginia.gov

Greetings Ms. Davenport,

Reference:  Draft Guidance Memo No. 22-2012 - Stormwater Management and Erosion & Sediment Control Design Guide

Stantec sincerely appreciates the opportunity to review the draft guidance document, and we are encouraged by the Department’s apparent goal of providing a comprehensive reference. However, Stantec staff have noted several questions and concerns with the guidance as proposed.  In general, we have arrived at a few common themes which have been summarized here.

Many of the subjects, while understandable and of legitimate concern, could be dealt with in a more context-specific manner, targeting the desired environmental outcomes and/or agency concerns. As drafted, this may lead to additional plan development burden, project cost, and schedule impacts if applied uniformly across all sectors. As such, the guidance may be overly restrictive and categorical, in many cases, and lacking nuance or context.

Many of the new recommendations are extrapolations from the current regulatory requirements and may not fully consider various perspectives regarding environmental value, practicability, or cost. These recommendations have the potential to become more stringent de facto minimum standards if implemented. We feel strongly that the practical application of the guidance should be vetted by the engineering community to which the document largely applies.

There appears to be enough of a departure from traditional practice in Virginia that additional stakeholder engagement, case study development, or policy consideration may be advisable for consistent and effective implementation. Further, the department currently has assembled a large and diverse group of engineers and industry professionals, the DEQ 2023 Stormwater Handbook Stakeholder Advisory Group, which could potentially be leveraged to examine and refine the guidance through an interactive process. It appears this could be a missed opportunity in bypassing that or a similar group, that could lead to fruitful and beneficial dialogue.

A more detailed itemization of specific comments is included under Attachment A. We look forward to continued discussion and working together with DEQ.

Respectfully,

Stantec Consulting Services Inc.

1. General:  Request inclusion of language clarifying exemptions and exceptions to Erosion & Sediment Control (ESC) and Stormwater Management (SWM) Law/Regulations.  Specifically, as they relate to “routine maintenance” under ESC vs “routine maintenance” under the Virginia SWM regulations; design for linear development projects related to stormwater management; and long-term maintenance agreements.

2. Chapter 2.000, Erosion and Sediment Control:  Recommend including text describing why only 8 of the 39 VESCH Chapter 3 – State Minimum Standards and Specifications are discussed in this section. 

3. Sections 3.302.1, B., 2 and 3.302.2, B., 2. - Define “un-attenuated” and confirm concurrence with 9VAC25-870-66, B. 4., Limits of Analysis.

4. Sections 3.303.1, C. and 2; 3.303.2, B., 2. - Define “un-attenuated” and confirm concurrence with 9VAC25-870-66, C. 3., Limits of Analysis.

5. Section 3.305, SHEET FLOW – General comments
   1. 9VAC25-870-66 criteria for non-erosive flows is the 2-year 24-hour storm event.  The 10-year 24-hour storm event is referenced throughout this section to determine non-erosive flow velocities from sheet flow.  Request revision to the reflect the 2-year 24-hour storm event consistent with other sections of 870-66.
   2. Please define “environmental features” as referenced in this section (e.g., 3.305.1, 4., B.). 

6. Sections 3.305.1, B., 3. and 3.305.2, D.:  Using a 1% slope, this equation results in a sheet flow length for a wooded area of 12.5 ft.  In certain instances, this short of a flow length would require design/installation of a stormwater conveyance system to divert flow, resulting in additional impact to forest/open space.  Suggest revising these sections to account for significantly short sheet flows in dense grass, brush, and wooded areas. 

7. Section 3.307, D. – Please clarify why a drainage easement is required for sheet flow. Example: How would a linear development project comply with this requirement?

8. Section 4.302: Linear Projects are defined here, however, Guidance Memo No. 15-2003 is not referenced.  Suggest referencing the Linear Project guidance memo in this section.

9. Section 5.301, D. and 5.302 D – Please provide additional information that supports adjusting HSG by one factor. 

August 31, 2022

Comments of the Chesapeake Solar & Storage Association (“CHESSA”) and the Solar Energy Industries Association (“SEIA”) (together, the “Joint Parties”) on DEQ Guidance Memo on Streamlined Plan Review for Construction Stormwater Plan and Erosion and Sediment Control Plans (Guidance Memo No. 22-2011) and Stormwater Management and Erosion & Sediment Control Design Guide (Guidance Memo No. 22-2012)

Executive Summary: 

1. JOINT PARTIES are generally supportive of Guidance Memo No. 22-2011.
2. JOINT PARTIES have concerns about Guidance Memo No. 22-2012 and would appreciate an opportunity to have further conversations with DEQ to address these concerns. 

Background: 

The Chesapeake Solar & Storage Association, generally known as CHESSA, represents every facet of the solar industry in Virginia, Maryland and the District of Columbia. Founded in 1984 as the Maryland-DC-Virginia Solar Energy Industries Association, CHESSA was formed to support the policy and regulatory needs of its members who design, sell, integrate, install, maintain, and finance solar energy and energy storage equipment. CHESSA’s association of over one hundred members serves residential, commercial, industrial, and institutional customers throughout the region.

The Solar Energy Industries Association (“SEIA”) is the largest national trade association for the solar industry. With more than 1,000 member companies nationwide, SEIA leads the transformation to a clean energy economy, creating the framework for solar to achieve 20% of U.S. electricity generation by 2030. SEIA works with its member companies and other strategic partners to fight for policies that create jobs in every community and shape fair market rules that promote competition and the growth of reliable, low-cost solar power. 

Major Concerns:

Major Concern #1

With respect to Section 5.500, Solar Panel Arrays, the Joint Parties remain concerned about the details of the grandfathering provisions for an effective date of December 31, 2024.  The March 29, 2022 technical memorandum (the “March Memo”) and the April 14, 2022 technical memorandum (the “April Memo”) use the threshold of “Interconnection Approval” by PJM prior to December 31, 2024, as further clarified by the April Memo.

The purpose of the April Memo was to provide some level of certainty for solar developers to provide a grandfathering provision to solar projects already in the pipeline of development to protect the economic investment in those projects. Unfortunately, since PJM has since indicated it intends to effectively shut down consideration of interconnection applications for at least two years beginning October 31, 2022, the April Memo creates significant uncertainty for solar developers with projects in the development pipeline.

The Joint Parties understand that DEQ believes the underlying policy should be that solar panels be treated as impervious and that new solar projects should be developed in accordance with these criteria. At the same time, however, changing this interpretation without a workable grandfathering provision would harm solar developers with solar projects already well into the pipeline. Therefore, the Joint Parties would respectfully request that DEQ change the grandfathering provision in Guidance Memo No. 22-2012 from using a PJM threshold as the trigger and instead use the same trigger the General Assembly used either in: (i) the 2022 Regular Session of the General Assembly’s House Bill 206; or (ii) Va. Code Section 58.1-3660. 

1. HB 206 provides a grandfathering provision as follows: “That any small renewable energy project for which an initial interconnection request application has been received and accepted by the regional transmission organization or electric utility by December 31, 2024, shall not be subject to the provisions of this act.”
2. Section 58.1-3660 provides a grandfathering provision as follows:  “For the purposes of this subsection, "application has been filed with the locality" means an applicant has filed an application for a zoning confirmation from the locality for a by-right use or an application for land use approval under the locality's zoning ordinance to include an application for a conditional use permit, special use permit, special exception, or other application as set out in the locality's zoning ordinance.”

Major Concern #2

With respect to Section 5.200 (A) and (B), Guidance Memo No. 22-2012 proposes a deviation between pre-development and post-development drainage areas of no more than 10%. While this approach might work in urban areas of the Commonwealth, it is not practical for large scale solar projects and is not the currently accepted state practice for SWM. The provisions that permit DEQ to require an applicant to redesign post-development are not workable for large scale solar projects, which are usually subject to a power purchase agreement over a long period of years. Perhaps DEQ could consider a “volume” approach instead of a “drainage area” approach to address this policy objective.

These proposed changes in state practices for SWM set out in Section 5.200 (A) and (B), Guidance Memo No. 22-2012 will likely significantly impact the amount of land needed for large scale solar projects, in addition to the costs of design and engineering, effectively requiring the solar developer to oversize the SWM facilities in each large scale solar project to make sure redesign does not happen once the solar project is built and deal sold, one way or the other. The Joint Parties respectfully request this concern be addressed in the final Guidance Document.

Major Concern #3

With respect to Section 3.307 regarding offsite sheet flow easements, the Joint Parties’ primary concern is subsection D, which has to do with offsite discharges through drainage easements. As written, this may require the developer to acquire additional land or request easements from adjacent landowners to meet the offsite easement requirement, despite the regulations lack of a mechanism to compel these easements. The Joint Parties recommend that the regulations defer to local jurisdictional authority regarding offsite drainage easements unless the development requires a new man-made drainage system.

Major Concern #4

With respect to Section 5.301 concerning pre-development runoff curve number selection methods, this section seems to be designed to push most land use into worse/more flood prone hydrologic soil groups (“HSGs”), whether or not that is the reality on the ground and irrespective of the surrounding adjacent land’s preexisting CN designation. While the Joint Parties agree that certain post development activity may contribute to the compaction of soil in such a way that it impacts drainage, the pre-development provision assumes that a given area is automatically moved to its next lowest HSG factor. The Joint Parties suggest that these sections be removed or reworded such that the provisions within are only triggered when recent adjacent developments suggest that the soil condition conflicts with those in the National Resource Conservation Service Engineering Handbook.

Major Concern #5

With respect to Section 5.500 concerning solar panel array configuration, the Joint Parties appreciate that DEQ is intending to provide potential flexibility to solar developers to soften the impact of solar panels being designated as “continuous impervious surfaces” for purposes of stormwater management. However, the Joint Parties are unfamiliar with rain sensing technology that orients panels in a vertical position during heavy rainfall. Such technology may well be prohibitively expensive, and vertically oriented panels may also pose a safety concern from a wind loading perspective.

Major Concern #6

Kimley-Horn, Timmons Group, and Strata Solar each submitted detailed comments on Guidance Memo No. 22-2011 and Guidance Memo No. 22-2012 at CHESSA’s request. The Joint Parties hereby associate their comments with those three sets of comments, as they are submitted. No doubt, there will be other industry and organizational comments as well.

Closing:

The Joint Parties appreciate the opportunity to comment on Guidance Memo No. 22-2011 and Guidance Memo No. 22-2012 and look forward to continuing to work with DEQ to address concerns and implementation of Guidance Memo No. 22-2012.

Kimley-Horn has reviewed the provided Guidance Memo No. 22-2012 – Stormwater Management and Erosion & Sediment Control Design Guide dated July 1, 2022 (Appendix B).  As an active participant in the design community, Kimley-Horn appreciates the opportunity to provide comments and request clarifications on the guidance document.

2.303 D.

• • INTERPRETATION:
    • It is our understanding that the new requirement is an analysis showing that the downstream conveyance system will contain and not be eroded by the total flow (off-site and on-site) from the 2-yr 24-hr storm event, considering the land cover to be the “worst-case” condition – meaning bare earth with impervious areas (panels and road, in the case of solar) installed (see section 5.500 A below). This analysis would document that the conveyance system can contain the flow within the system without overtopping, and that the velocity generated from the 2-yr 24-hr storm event is non-erosive for the lining of the downstream conveyance system.
  • CLARIFICATION:
    • If a sediment basin or trap is not modeled, how will DEQ determine the peak outflow from the facility?
    • Based on the current VESCH design guidelines, if a sediment basin is modeled, it should be modeled assuming the dewatering method is clogged. Is this the intent when calculating the peak flow from the sediment basins for the downstream analysis?
    • Is DEQ expecting to see any final improvements (roads, inverters, foundations, panels, etc.) included in the hydrology calculations for the contributing drainage areas?
    • We further request that DEQ provide clarification for the extent of downstream analysis of adequacy for the 2-YR 24-HR Storm.
    • Please clarify what the process to extend the period of use beyond 18 months would be.
  • CONSEQUENCE:
    • We anticipate this new requirement to cause sediment basins and traps to be larger, for new downstream improvements required for receiving channels, and for design costs and time to increase.
  • SUGGESTION:
    • Due to the temporary nature of sediment basins and traps, a minimum threshold for contributing drainage area could be established under which an analysis would not be required.
    • DEQ provides formulas for calculating allowable peak discharge (1-year 24-hour) into natural conveyance systems in Section 3.302.3, but does not provide similar formulas for the E&S condition.  DEQ could provide a similar formula/approach for the 2-year 24 hours E&S condition.
    • DEQ could offer a tabular methodology to estimate peak discharge for sediment basins and traps considering the routed effect but avoiding level pool modeling. This could be summarized in a spreadsheet using rational method.

2.303 G.

• • INTERPRETATION:
    • This section specifies the land cover for hydrologic calculations during the E&S phase but is inconsistent within the guidance document on the land cover conditions which should be used for temporary E&S calculations.
  • CLARIFICATION:
    • Section 5.500 A. specifically outlines that solar projects should consider the panels as impervious (and therefore included) when computing runoff computations for E&S controls. 
    • Please clarify the rationale for and basis of requiring a new hydrologic analysis methodology based on land use.  There are other large land uses (industrial and single-family developments, for example) that take significant time for pervious areas to stabilize but are not mentioned here.
    • Additionally, please clarify that it is the intent of this document to continue accepting rational method as a suitable method of computing runoff for the temporary E&S condition. There have been recent (project specific) comments from the department that this may become unacceptable in the future.
  • CONSEQUENCE:
    • We anticipate this new requirement to cause sediment basins and traps to be larger and for design costs and time to increase
  • SUGGESTION:
    • Any consideration of proposed impervious area should be limited to the final hydrology.

3.302.1 A.1.

• • INTERPRETATION:
    • It is our understanding that this section requires analysis of channel protection up to and including the point of analysis.
  • CLARIFICATION:
    • It has been general practice to use 9VAC25-870-66B.1.a. of the state code to satisfy channel protection if your limits of analysis (LOA) is reached while simultaneously reaching a “natural stormwater conveyance system”.   If this is no longer the case, more outfalls will need to meet energy balance which will result in larger basins or eliminating potential developable areas.
    • Please clarify if the intent of this document is to include the receiving channel at the point of analysis (a stream with localized flooding, for example) in the channel protection analysis, or if this section is consistent with previous policy.
  • CONSEQUENCE:
    • This requirement could create the need for increased design costs and time.
    • This requirement could also create increased construction costs for improvement of downstream receiving channels.
  • SUGGESTION:
    • Provide clarification that if the limit of analysis for channel protection calculations is reached while simultaneously entering a natural stormwater conveyance system, 9VAC25-870-66B.1.a. has been met.

3.302.1 C.2.a.-b. , 3.303.1.D.1. & 3.303.2.C.1.  

• • INTERPRETATION:
    • It is our understanding that these sections require “field surveyed cross-sections” at a specific frequency to analyze the adequacy of the receiving channel.
  • CLARIFICATION:
    • Provide clarification if analysis done at the specified frequency with cross sections of flown/LiDAR topographic surveys would satisfy the department, or if manually surveyed cross-sections would be required.
  • CONSEQUENCE:
    • This will create a significant expense and potentially schedule constraints for large projects which typically utilize flown/LiDAR topographic surveys for design.
    • There are risks that adjacent property owners may not provide access required for ground field survey of the stormwater conveyance.
  • SUGGESTION:
    • Allow for flown/LiDAR topographic surveys to be utilized for the analysis of receiving channels.

3.302.4 A-B

• • INTERPRETATION:
    • It is our understanding that this section identifies how to determine a conveyance system’s flood-prone area by calculating the water surface elevation during the 1-yr 24-hr storm event.
  • CLARIFICATION:
    • Please confirm that the definition of “flood-prone areas” considers what is flooding in the 10-yr 24-hr storm event.
    • Note that the purpose of identifying a “flood-prone area” is to determine potential limits of analysis (LOA) for flood protection calculations, which consider the 10-yr 24-hr storm event.
  • CONSEQUENCE:
    • Considering flood prone areas based on the 1-yr storm would result in significantly more modeling and documentation to comply with flood protection requirements.
  • SUGGESTION:
    • Confirm that the definition of “flood-prone areas” considers what is flooding in the 10-yr 24-hr storm event.

3.303.1.C.3. & 3.303.2.B.3.

• • INTERPRETATION:
    • It is our understanding that this section identifies how to determine the limit of analysis for flood protection calculations.
  • CLARIFICATION:
    • Please clarify that the intent is to also include “flood-prone areas” as an adequate limit of analysis, as mentioned in 9VAC25-870-66.C.3.c.
  • CONSEQUENCE:
    • As written, this section of the guidance document is not consistent with the language of the Virginia Code.
  • SUGGESTION:
    • Revise language to match 9VAC25-870-66.C.3.c.

3.305.1.A.

• • INTERPRETATION:
    • It is our understanding that this section requires analysis to confirm there is no increase in both volume and velocity.

• • CLARIFICATION:
    • Based on section 9VAC25-870-66.D. of the Code, only increased volumes of sheet flow require identification and evaluation for down-gradient effects.
    • Please confirm if DEQ intends to require analysis of sheet flow that is not an increase in volume.
  • CONSEQUENCE:
    • This will require additional analysis and documentation beyond what is required by the Code.
  • SUGGESTION:
    • Limit analysis only to increases in sheet flow which increases runoff.

3.305.2.A.

• • INTERPRETATION:
    • It is our understanding that this section is implying that sheet flow leaving a level spreader cannot be analyzed for quantity as sheet flow but must meet channel and flood protection requirements.
  • CLARIFICATION:
    • Please confirm if sheet flow leaving a level spreader may be analyzed for quantity as sheet flow.
  • CONSEQUENCE:
    • This will create increased design costs and time, and potentially increase construction costs for improvements to outfalls that otherwise would have been considered sheet flow that honors natural drainage patterns.
  • SUGGESTION:
    • This guidance indicates that the department does not consider discharge from a level spreader to be “sheet-flow”, without consideration for the calculations which could show it induces flow that meets sheet flow characteristics.

3.307

• • INTERPRETATION:
    • It is our understanding that this section will require an off-site easement to be recorded if an area that is currently leaving the site as sheet flow is designed to maintain the existing drainage patterns.
  • CLARIFICATION:
    • Please provide further explanation why an off-site easement would be required for an existing outfall. 
    • Please clarify how this guidance would reconcile with existing code in local facility manuals. 
    • Please clarify if drainage easements will be enforced with standard provisions and deed instruments, and if DEQ is requiring local MS4 Permit holders to become maintainers of last resort.
  • CONSEQUENCE:
    • Without an enforcement mechanism, adjacent landowners could refuse to grant an easement on existing outfalls. 
    • This section of the document will therefore increase the likelihood of deviating from existing drainage patterns when easements are impossible to obtain, or otherwise render projects otherwise fully entitled impossible to build without full consent from adjacent properties for outfalls already functioning.
  • SUGGESTION:
    • Require easements only for newly created, man-made convenance systems.  Defer to local jurisdictions when facility manuals already specify requirements for easements.

4.301.C

• • INTERPRETATION:
    • It is our understanding that this section would require separate analysis of phosphorus load and therefore removal requirements for projects spanning multiple HUCs.
  • CLARIFICATION:
    • Please clarify the intent of separating pollutant load calculations.
    • Please clarify that phosphorous loads can continue to be met with credit purchases in adjacent HUCs.
  • CONSEQUENCE:
    • Separating calculations will require additional design cost and time.
  • SUGGESTION:
    • Require separate calculations for phosphorous load requirements only if the project spans multiple HUCs AND is non-contiguous. 
    • Allow for a percentage of the phosphorous reduction required be achieved on-site in the adjacent HUC.

Chapter 5: Good Engineering Design Practices

GENERAL CLARIFICATION: Please provide an explanation for the section.  Is DEQ attempting to suggest best practices for Engineers, establish a framework for policy guidance, or setting the stage for upcoming code?

5.200 B.

• • INTERPRETATION:
    • It is our understanding that this section gives general guidance for preservation of existing drainage patterns only.
  • CLARIFICATION:
    • Please confirm that this is a recommendation not a requirement.
  • CONSEQUENCE:
    • If this section becomes a strictly enforced requirement, it will lead to increased design cost and time. Given the strict requirements surrounding sheet flow and adequate outfall locations, this is going to be a difficult parameter to maintain.
  • SUGGESTION:
    • Make this a recommendation not a requirement. 

5.301 D. 1. & 5.302 D.1.

• • INTERPRETATION:
    • It is our understanding that these sections require adjustment of all pre-development soil groups by one factor of improved drainage, then taking the “adjusted” pre-development HSG from section 5.301 D.1. and further adjusting for the post-developed condition.
  • CLARIFICATION:
    • Please clarify the intent and justification of this requirement.  Does DEQ not want engineers to utilized NRCS soil survey data?
  • CONSEQUENCE:
    • This provision would require more detention of onsite runoff, which would increase construction cost by increasing the size of basins.
  • SUGGESTION:
    • Adjust onsite hydrologic soil groups only for projects where testing from recent adjacent projects have demonstrated inaccurate soils in the NRCS soil surveys.   

5.302 D.3.-4.

• • INTERPRETATION:
    • It is our understanding that this section requires field-testing the on-site HSG after construction has been completed but prior to project close out.
    • It is further our understanding that should the field investigation return results that support a higher HSG than what was proposed in the design plans, the design must be updated to account for the change in HSG.
  • CLARIFICATION:
    • Please explain the precedence and intent of this requirement. 
    • Does DEQ desire to update post-development hydrology after construction, then modify constructed facilities?
  • CONSEQUENCE:
    • This is a significant risk to construction costs.
    • This testing would be performed once perimeter stormwater measures are designed, installed, and functioning, which is itself a significant cost increase on large sites.
    • If the field testing returned data that showed the HSG was divergent, it presents a significant risk that the design and ultimately what has already been built and stabilized would need to be expanded to “handle” the field-tested HSG values. This could have unnecessary impacts to the environment if disturbance of previously stabilized areas is required to meet this guidance.
    • There is also no protection here for an iterative reconstruction and testing of drainage areas.
  • SUGGESTION:
    • Limit onsite testing of hydrologic soil groups to one option for analysis of sites that are not performing after construction, rather than an expected procedure for every drainage area for every land development project in the state.

5.500 A.

• • INTERPRETATION:
    • It is our understanding that this section requires all installed solar panels to be considered unconnected imperious area per 210-VI-TR-55, Chapter 2.

• • CLARIFICATION:
    • This section makes the assumption that the land beneath the horizontal projection area of the solar panel is impervious, but does not account for any initial abstraction nor infiltration of the soil, porosity, and roughness of the stabilized meadow condition that will and does establish under those panels.
    • Please clarify how the sheet flow under the panel over grass is being accounted for.
    • Please clarify if any case studies have been performed by DEQ or research reviewed to conclude that the sites demonstrate hydrologic performance comparable with traditional unconnected impervious area.

• • CONSEQUENCE:
    • This will create increased design cost and time to model the increased number of retention and treatment facilities.
    • This will create increased construction costs due to the increased number and size of retention basins to handle additional runoff.
    • This will create increased construction costs due to the increased number and size of BMPs to handle additional treatment.
  • SUGGESTION:
    • Enact a study period to monitor the performance of several solar facilities in Virginia to measure an empirical characterization of runoff compared to traditional unconnected impervious. 

5.500 B.

• CommentID: 127479

AES CE appreciates the opportunity to comment on GM No. 22-2012. We have observed many technical and grammatical errors in the document and recommend that guidance memo be updated and reissued for public comment.

1. “[P]reviously DEQ-approved solar project that does not obtain an interconnection approval by ….. may submit a revised stormwater management plan to DEQ for a fast-tracked (expedited) review...”

AES CE seeks clarification on the “expedited process” that DEQ is referencing. Is this the current DEQ 45-day expedited review process or is DEQ referencing the proposed streamlined review process per GM22-2011?

2. “Permanent or temporary soil stabilization should be applied within seven (7) days to all denuded areas at final grade. See Minimum Standard #1, 9VAC25-840-40 1…

A permanent vegetative cover should be established on all denuded areas not otherwise permanent stabilized. See Minimum Standard #3, 9VAC25-840-40 3, and Standard and Specification 3.32 (Permanent Seeding).”

A timeline for the application of initial soil stabilization is identified in this section; however, there are no clear timelines for re-stabilization of previously stabilized but not established denuded areas that do not exhibit excessive erosion. AES CE seeks clarification on whether there is a required timeline for previously stabilized yet not established denuded areas or if these areas, although not established, are considered stabilized and no additional stabilizing measures are necessary.

3. “Specifically, the memo states that ground mounted solar panels shall be considered unconnected impervious cover as defined in Chapter 9, Part 630 of the NRCS National Engineering Handbook.”

AES CE seeks clarification on the basis of consideration (i.e., baseline studies) for determining ground mounted solar panels as “unconnected impervious surface”? AES CE recommends a formal study be conducted that evaluates ground surfaces during construction, including vegetated and non-vegetated surfaces, with regard to the issue of erosion concerns associated with ground mounted solar panels. Erosion concerns may be associated with vegetation management under the solar arrays during construction, which may become irrelevant once uniform permanent vegetation is established. AES CE recommends conducting additional studies and evaluating these considerations before implementing drastic design alterations and requirements that may not resolve the underlying issue of erosion.

4. “Should a project owner elect to implement rain-sensing technology such that the solar panels rotate to a vertical position during storm events, the horizontal projected area may be assumed to be zero...”

AES CE requests the DEQ define the term “storm event” in terms of duration and rainfall amount. A clear definition of a storm event would aid in determining rain-sensing technology sensitivity settings. Additionally, AES CE recommends encouraging a dynamic tilt method to disperse rainfall over a larger surface area, reducing both the volume of the impact and the area affected. Tracking systems cannot achieve a vertical position, as DEQ has referenced, but can be set to stow at their maximum tilt angle. AES CE requests the ability to further work with the DEQ on determining tracking system angle variability when considering stormwater calculations and best practices during these storm events.

5. Section 6.500 subsection I table and “HSG” means Hydrologic Soil Group. See Appendix 6C of 1992 Virginia Erosion & Sediment Control Handbook for groupings.”

AES CE recommends the inclusion of the U.S. Department of Agriculture Natural Resources Conservation Services Web Soils Survey for reference to hydric soil group information to prevent the utilization of outdated data. 

6. The DEQ SWM ESC 24” x 36” Cover Sheet

1. • Section D – “PROPERTY OWNER” information

AES CE recommends reconsidering how this is outlined on the cover sheet as large-scale projects will typically consist of multiple properties and property owners. This information is best provided in a table format for clarity and ease of reference.

2. • Section F - “OFFSITE SUPPORT ACTIVITY INFORMATION”

AES CE requires clarity on what constitutes an offsite support activity. This is not defined in either GM22-2011 or GM22-2012 and additional information is necessary to understand what type of activity would fall into this category.

3. • Solar Specific Requirements part II. “SOLAR PANEL ARRAY HORIZONTAL PROJECTED AREA”

AES CE requires clarity on what equation is being referenced in this section. The equation components are provided but the equation is not included under this section. 

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.

2. 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 3^rd party?

3. 2.303 – Temporary Sediment Basin – D.

1. • 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?”

2. 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.

3. 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.
4. 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.

5. 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.

6. 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 Q_dev > Q_pre”, but also “Under no circumstances should Q_dev be required to be less than the forested energy balance equation written as: Q_forest x  
     • When Q_forest x  > Q_pre, what should be selected as the allowable flow flow rate?
     •  

7. 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?

8. 3.302.5 – Is the “site” defined by the LOD, the lease limits, or the property boundary?

9. 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.” 

10. 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.

11. 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.

12. 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.

13. 5.301.D – Who makes determination on “Previously disturbed soils?”

14. 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?

15. 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.

16. 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?

I represent PJM Interconnection in Virginia on Executive and Legislative matters, I am writing to provide technical comments on the proposed guidance memo 22-2012 that was published in the Virginia Register on August 1, 2022.  The comments are limited to the first full paragraph at top of page 44 of DRAFT Guidance Memo No. 22-2012 - Stormwater Management and Erosion & Sediment Control Design Guide 

The following technical changes shown in red below are recommended to clearly specify the applicable document that is referenced from the current interconnection approval process at PJM as well as to accurately track the proceedings underway at the Federal Regulatory Management Commission (FERC) regarding approval of the new queue process proposed by PJM and the NOPR FERC has issued regarding the interconnection processes used by PJM and other RTO’s around the country.  The proposed technical changes are as follows:

To provide further guidance, "Interconnection Approval" can be demonstrated by the issuance of (1) the System Impact Study as defined in the PJM Manual 14a: New Services Request Process, Section 4.3 (Revision:29, Effective Date: August 24, 2021 or as may be amended thereafter), or (2) an equivalent study by PJM under any process approved by FERC that results from the PJM Interconnection Reform Process or (3) an equivalent study by PJM under any process approved by FERC as a result of the Notice of Proposed Rulemaking (NOPR) that was issued by FERC on June 16, 2022 regarding expediting the interconnection approval process. "Interconnection Approval” can also be demonstrated by the issuance of a Small Generator Interconnection Agreement for projects that go through the state interconnection process. 

I am also advised that given the time it will take for FERC to approve and PJM to put into effect their proposed or any other new interconnection process ordered by FERC, it is highly unlikely that any project that does not receive a system impact study under (1) above, the current PJM process, will receive an “equivalent” study from PJM prior to the December 31, 2024 deadline established in this section of the proposed guidance.

I hope you find this information to be helpful and please contact me if you have any questions on this. 

Sincerely,

Philip F. Abraham

Director and General Counsel

The Vectre Corporation

August 31, 2022

Ms. Melanie Davenport

Commonwealth of Virginia

Department of Environmental Quality

Director - Division of Water Permitting

1111 East Main Street

Richmond, VA 23219

Re:      Guidance Memo No. 22-2012 Public Comment

Stormwater Management and Erosion and Sediment Control Design Guide

Dear Ms. Davenport:

Hewitt Solutions is an active and experienced design and consulting firm in the solar land development space that has worked very closely with DEQ for several years. We appreciate the opportunity to review the aforementioned guidance memo and offer the following comments: 

Section 2.302.C (Page 9)

• Clarify the requirements for instances where a Sediment Trap will be converted to a permanent SWM facility. What would be the standards for this type of design?

Section 2.303.D (Page 9)

• The VESCH says outfalls should be to an “adequate channel;” however, SWM regulations say concentrated outfalls should be to a “stormwater conveyance system.”  Both adequate channel and stormwater conveyance system have different definitions in their respective regulations. Clarify whether ESC outfalls are intended to be to a stormwater conveyance system or an adequate channel.

Section 2.303.D.1.d (Page 10)

• Sediment basin stipulation for an “adequate outfall” analysis requires 2-yr capacity and velocity checks to verify channel adequacy. Clarify that this is required of one cross-section at the basin discharge without further downstream analysis.

Section 2.303.E (Page 11)

• Clarify and define “structural integrity” required for sediment basins in the 25-yr storm. 
• VESCH Specification 3.14 states 25-yr storm but does not imply 24-hr storm. Clarify if Rational Method is not permitted in sediment basin design. 

Section 3.302.1.A.1 (Page 15)

• The last paragraph states “If a natural stormwater conveyance system is encountered before the limits of analysis is reached, the stormwater peak discharge should satisfy the requirements for discharges to natural stormwater conveyance systems.” Clarify that if the limit of analysis and a natural channel are reached simultaneously – for example, at a piped outfall confluence to a major waterway – that this does not require reverting to natural channel (energy balance) requirements.

Section 3.302.1.C.2.a (Page 16)

• For both subsections a and b, clarify the need for field-surveyed channel cross-sections. Public LiDAR is a better match for the general nature of limits of analysis calculations than field-surveyed cross-sections. In addition, field survey for additional downstream cross-sections is frequently unobtainable due to restrictions of private property access.

Section 3.302.1.C.3.a (Page 16)

• Clarify or reference source for 10 fps velocity limit in RCP; suggest a higher recommended maximum.

Section 3.302.3 (Page 18)

• In the past, existing natural swales that were not jurisdictional were not considered part of a stormwater conveyance system, though “…unimproved ephemeral channels, wetlands, or swales” are listed as part of the flood-prone area in this section. We support the inclusion of these features; clarify Section 3.302.4 to include them as well (see comment below.)

Section 3.302.3.A (Page 19)

• Variations in how the improvement factor should be applied has been experienced in the past given the description of “total land disturbance.” Suggest further clarifying the terms “site” and if improvement factor area designation of 1 acre applies to disturbed area within the given drainage area or, in fact, refers to total disturbed area for the project.

Section 3.302.4.B (Page 20)

• Clarify what information is required when submitting flood-prone area documentation and in which scenarios the documentation is acceptable. Approving certain buffers and areas on a “case-by-case basis” gives no further direction than exists today as to what is permissible. 

Section 3.303.1. (Page 20)

• Suggest providing additional guidance on definition of Point of Discharge and where it makes the most sense to select the analysis point. The existing receiving channel is often the logical choice for the point of analysis, but typically DEQ requires the analysis point to be at the LOD which is not quite in the stream bottom. 

Section 3.303.1A (Page 20)

• Suggest providing additional reasoning why reducing post development flows to equal to or less than pre-development conditions is not acceptable in areas where localized flooding is not experienced.

Section 3.305.1.B.1 (Page 25)

• Clarify requirement of 10-year velocity calculation for sheet flow in both the pervious/unconnected impervious and level spreader cases. A 2-year velocity calculation is standard practice to check for erosive velocities.

Section 3.305.2.A (Page 27)

• Suggest clarifying and updating this section: is the intent to specify that energy balance and channel protection must be met prior to concentrated flow being discharged through a level spreader that conforms to sheet flow requirements? This is not a requirement of 9VAC25-870-66.D.

Section 3.305.2.B (Page 27)

• Clarify why this allowable velocity table is different from the previous versions of this table pasted in this document. This version doesn’t match VESCH Table 5.14.

Section 3.307.D (Page 33)

• This section appears to dictate that an off-site drainage easement is required for “…any proposed off-site sheet flow paths…” but only includes a section on sheet flow from level spreaders. Clarify with specific carve-outs in this section confirming that no easements are required for pervious/unconnected impervious sheet flow. If engineering calculations as required in Section 3.305.1.A are provided showing that sheet flow volume and velocity are decreased/improved from existing condition, no easement should be required.
• This section states that level spreaders are subject to off-site sheet flow easements except in the Safe Harbor case. Clarify the exceptions to include scenarios in which the volume of sheet flow has decreased. If engineering calculations as required in Section 3.305.1.A are provided showing that sheet flow volume and velocity are decreased/improved from existing condition, no easement should be required.

Section 4.400 (Page 38)

• Consider modifying the VRRM to consider the positive impact of transitioning higher nutrient load land cover conditions to lower nutrient load land cover conditions, similar to how water quantity is analyzed in comparing pre and post conditions. This practice should be considered a pollutant removal practice and added to Section 4.403.B.

Section 5.200 B (Page 40)

• Suggest removing the “good engineering practice” of keeping post-dev drainage areas to within 10% of the pre-dev areas. This is not a stipulation of the stormwater code and is usually only done to comply with DEQ’s own requirement to route concentrated stormwater runoff to an approved stormwater conveyance system. Channel protection, flood protection, and sheet flow calculations and requirements as outlined elsewhere in the guidance memo more than protect downstream waterways in the case where pre- and post-DAs are greater than 10% different.

Section 5.301.D (Page 40)

• Suggest more clarity on pre-development analysis adjustments, as these are not typical. For example, are cultivated agricultural fields considered “previously disturbed”?

Section 5.500 (Page 44)

• Clarify the process for the “fast-tracked (expedited)” review that solar projects with an approved DEQ plan but not a prior approved interconnection date.
• Clarify the definition of solar panels that are “directly connected to the stormwater conveyance system” throughout this section.  

Section 5.500.D (Page 46)

• To our knowledge, the rain sensor guidance is not practicable: solar panels cannot physically rotate to 90-degrees (i.e. perpendicular to the ground) so that the horizontal impervious area is zero. Neither is it a fair assumption to require the minimum angle (parallel to the ground) for all calculations. Suggest refinement of this section.

6.500 Plan Submission Checklist (Page 50)

• If DEQ is not the VESCP authority, clarify if the ESC portion of the checklist need to be filled out, and if the checklist will be deemed incomplete if not.

• Clarify where to provide the latitude & longitude of SWM facilities: middle of facility, center of spillway, etc.

We appreciate your time and consideration of the comments within.

Respectfully,

The Hewitt Solutions Team

Mrs. Melanie Davenport

Virginia Department of Environmental Quality

1111 E. Main St., Ste. 1400

Richmond, VA 23219

Re: Comments on Proposed Guidance Memo No. 22-2012

Mrs. Davenport,

Contech® Engineered Solutions is appreciative of the opportunity to provide public comment on the proposed Guidance Document. We recognize significant effort and resources were put into creating this draft. The production of this document is evidence that the Department remains committed to providing comprehensive SWM and ESC design guidance. We wholeheartedly support this concept. However, as presented, the guidance falls short of creating the subject matter clarity necessary for implementation at this time. We recommend delaying the effective date until the engineering community's concerns have been adequately addressed. 

A detailed list of concerns identified during our review is included below. We look forward to continued dialogue with DEQ regarding this critical water quality matter. 

Sincerely,

Jacob Dorman

Comments:

Chapter 1.00 Introduction

1) Sec. 1.10 General: While noted that each ESC or SWM Plan is subject to the version of guidance in effect at the time of plan acceptance, additional discussion around how this new guidance affects plans currently under design/review would be appreciated.

2) Sec. 1.10 Reference Material: DEQ has convened a Stormwater Advisory Group to assist with the examination, review, and, likely, consolidation of many of the referenced standards and practices into a single handbook. The resulting 2023 ESC/SWM Handbook will guide the plan review process upon implementation, and it should be acknowledged that GM22-2012 is an interim guidance document in need of future updating. This will create the expectation that it's a living, breathing document making use of the best available science and technology. 

Chapter 2.00 Erosion and Sediment Control

3) Sec. 2.200 Interpretation: This guidance is intended only for areas of the Commonwealth were DEQ is the ESC program authority per Sec. 1.10 of the draft. The reference to "local government" is unnecessary. 

4) Sec. 2.301-308: Sections discuss only a few of the accepted 39 ESC practices listed in the ESC Manual. It is recommended that this section incorporate the ESC Manual by reference for clarity and simplicity.

Chapter 3.00 Stormwater Management- Water Quantity

5) Sec. 3.302 Channel Protection: In Sec. 3.302.1.C.3.a, only reinforced concrete pipe (RCP) is addressed under permissible velocities. Other types of pipes (CMP, HDPE, etc) are used for stormwater conveyance and should have permissible velocities included.

6) Sec. 3.306 Stormwater Discharges to Karst Features: In Sec. 3.306.I, the guidance identifies preferred BMPs for karst, including Bioretention (DEQ Specification #9) and Dry Swales (DEQ Specification #10). These two practices rely, in part, on infiltration into the subsoil to achieve full runoff reduction and pollutant removal effectiveness. In karst areas, these specification suggest using an impermeable. This inhibits runoff reduction and creates a flow-through practice. If these practices are to be used in karst, runoff reduction crediting should be reduced to improve parity with other flow-through practices. DEQ should also address applicability of detention practices in karst areas.

7) Sec. 3.307 Drainage Easement: DEQ specifies easement widths in Sec. 3.307.A, 3.307.B, and 3.307.C that may conflict with local requirements or standards. It is recommended DEQ cite any applicable state code sections providing for the establishment of minimum easement widths.

Chapter 4.0 Stormwater Management- Water Quality

8) Sec. 4.303 Brownfield Development: The term "brownfield" is not defined anywhere in the guidance and needs to be in order to ensure consistent implementation.

9) Sec. 4.305 Stormwater Discharges to Karst Features: In Sec. 4.305.H, filtering practices (DQ Specification #12) are one of the preferred BMPs. Section 5 of the specification addresses the use of proprietary filters listed on the BMP Clearinghouse. With recent changes to the certification process for proprietary filters as a result of HB1224 in the 2022 General Assembly, it may be helpful to create a new category within this section that addresses the beneficial use of these compliance tools.

10) Sec. 4.400 Virginia Runoff Reduction Method: While environmental site design (ESD) should be encouraged, it is important to note that ESD strategies are not suitable for all development situations. While more germane to a future VRRM guidance update than this one, there are compliance options available today that weren't considered when the original VRRM was developed in 2008 and subsequently updated in 2016 (GM16-2001). DEQ should utilize the broadest possible suite of effective, robustly monitored and studied BMPs available today.

11) Sec. 4.400 Virginia Runoff Reduction Method: Current VRRM guidance states that the tool can evaluate BMPs in series (e.g. treatment trains) to meet water quality requirements. This is helpful, but DEQ is aware more robust treatment train guidance is needed. Designing with distinct unit removal processes will ensure pollutants are reduced to maximum extent practicable. GM22-2012 is a great opportunity for DEQ to explain proper treatment train alignment (the most common being the less effective practice upstream of the more effective one) and provide examples using non-proprietary and proprietary practices. 

Appalachian Power Company (APCO) appreciates the DEQ focus on summarizing the key points from the current regulations to aid in plan development and review.  We offer the following comments on the draft Guidance Memo.

APCO is concerned with the language used for Sheet Flow in Section 3.305 as the current requirement for the NPDES permit program are to regulate point source discharges.  Sheet flow is not defined by Virginia as a point source discharge.  The requirements proposed by DEQ in 3.305.1 create a burden on the regulatory community and take engineering guidance for determining storm runoff volume and peak rate of discharge and mis-apply those procedures to actual ground conditions for short durations of overland flow.  Further study and analysis by technical groups is necessary to evaluate sheet flow across the Commonwealth so that additional design and costs associated with post-construction stormwater facilities are necessary components to water quantity compliance.

APCO regrets that Guidance Memo 15-2003 or any other technical guidance for development of linear project plans was not included in this document and urges DEQ to look into ways that the urban watershed planning tool of the Virginia Runoff Reduction Method (VRRM) called for in 9VAC25-870-65 can be adapted to take into account linear projects and access roads to remain in often mountainous terrain in southwest Virginia.  Following Guidance Memo 15-2003 requires reclamation of all areas to predevelopment runoff characteristics, which imposes significant costs with unquantified environmental benefits.  Our ratepayers are very concerned at this time with rising costs of living and APCO is looking to ensure that investments in construction projects are prudent and meet the intent of the regulations.

Our consultants have great difficulty in applying energy balance to existing driveways, farm roads, and logging roads we utilize for access to our high voltage electric lines.  There are currently no stormwater BMPs on the clearinghouse utilized by DEQ that apply to mountainous terrain and our typical linear projects, most are intended for commercial developments on grades found in the Piedmont and Tidewater regions.  This leaves APCO in a disadvantage when trying to retain access for maintenance and inspections, or work with landowners who want to keep roads on their individual properties. 

APCO feels that the minimal options for water quality land cover also create additional costs and burdens by not allowing maintained rights of ways and disturbed areas to exist as open space without using that as credit for quality and having to place deed restrictions on those areas.  APCO uses managed turf instead which implies a nutrient load such as a golf course or manicured lawn that is not consistent with our typical areas of disturbance post-construction.  It is noted in this Guidance Memo that DEQ is currently reviewing the water quality design criteria.  APCO recommends that DEQ look to review the technical criteria not just for the Chesapeake Bay watershed.  APCO supports the development of a new stormwater management policy for linear utility projects that maximizes the flexibility of utilities to install and maintain access to their infrastructure at the lowest possible cost to the electric consumers in the Commonwealth, while properly taking into account the need to manage stormwater point source discharges from construction activities.

We appreciate the opportunity to review and comment on this document and feel that with additional work it can become a successful tool for the regulated community.

Sincerely,


Jared Webb, PE

FROM: Home Builders Association of Virginia (Andrew Clark – Vice President of Government Affairs)

Subject: Streamlined Plan Review for Construction Stormwater Plan and Erosion and Sediment Control Plans (Guidance Memo No. 22-2011) and Stormwater Management and Erosion & Sediment Control Design Guide (Guidance Memo No. 22-2012)

Ms. Davenport: Thank you for the opportunity to comment on the Department of Environmental Quality’s proposed Guidance Memos 22-2011 and 22-2012. The Home Builders Association of Virginia (“HBA of Virginia”) has reviewed the draft guidance documents and, in consultation with member firms across the Commonwealth, prepared the following comments for your consideration.  We have included several general comments which we would ask to be included in the record for both Guidance Memos; we have also included comments related to specific provisions of Guidance Memo 22-2012.

Executive Summary/General Comments:

• The HBA of Virginia is sincerely appreciative of the tremendous momentum in the Department over the last nine months towards addressing many of the regulatory issues affecting the housing industry and economic development in the Commonwealth.  The Director and Department staff have worked diligently to open the lines of communication with various stakeholders, identify pressing issues, and expeditiously implement short- and long-term goals and solutions.  We believe that these efforts will have a positive impact on the Commonwealth’s environmental and economic development objectives.
• Both proposed Guidance Memos seek to enhance efficiencies and advance “best practices” for the Department and the regulated community; the HBA of Virginia is fully supportive of any balanced and common-sense efforts to accomplish those goals.  However, the General Assembly must also proactively address the Department’s budgetary constraints and staff shortages, which our industry views as a significant impediment to enhanced efficiency in regulatory reviews and sustained communication between regulators and the regulated community on best practices. 
• HBA of Virginia Positions on Proposed Guidance Memos:
  • Guidance Memo 22-2011: Support
  • Guidance Memo 22-2012: HBA of Virginia has identified several questions and concerns, which are detailed below; request additional time for stakeholder engagement and consideration of revised language and/or alternative approaches to meeting overarching objectives.
• Based on discussions with Department staff, the HBA of Virginia believes that many of the concerns raised by stakeholders re: Guidance Memo 22-2012 can likely be resolved through additional discussions between the Department and the regulated community.

HBA of Virginia - Guidance Memo 22-2011:

The Home Builders Association of Virginia supports the Department’s efforts to provide streamlined reviews of stormwater management (SWM) and erosion and sediment control (ESC) plans in localities where the Department serves as the VSMP or VESCP authority and provided that certain conditions are met.

HBA of Virginia - Guidance Memo 22-2012:

The Home Builders Association of Virginia acknowledges that the Department is attempting to address several legitimate issues through its Guidance Memo 22-2012.  However, our members have raised substantive questions about, and concerns with, the proposed document and various provisions which may adversely impact the residential land development industry and other stakeholders. We are extremely grateful for the time that Department staff has dedicated to meeting with HBA of Virginia staff and member firms and remain committed to continue working with the Department on this proposal.

Primary Concerns

5.200 (A) and (B)“Post-development drainage areas and drainage divides should replicate, as nearly as practicable, the pre-development drainage areas and drainage divides. See Va. Code § 62.1-44.15:28 A 10.”

HBA of Virginia Comments: This statement seems to conflict with Va. Code § 62.1-44.15:28 A 10.  It replaces the parameters of rate of flow, runoff characteristics, and site hydrology with “drainage areas and drainage divides” and ignores the provision that the law provides for improvement of existing erosion and flooding conditions. 

“Post-development drainage areas should deviate from the pre-development condition by no more than plus or minus 10%.

HBA of Virginia Comments: As proposed, Section 5.200 (A) and (B) would allow a deviation between pre- and post-development drainage area conditions no greater than 10%.  While possibly feasible in dense, urban communities, compliance with this requirement outside of Northern Virginia is generally not practical for many sites and types of projects given varying pre-development conditions (i.e., topography, size of site, geographic location). Compliance would likely result in a significant increase in the number of onsite BMPs.

Based on feedback that we received from our member firms, we believe that additional discussion between the Department and the regulated community may help identify a more manageable, alternative approach.

5.302 (D)“The hydrologic soil group (HSG) used for post-development CN selection should be based on the ultimate development condition of the subject land-disturbing activity…For disturbed soils (e.g., pre-development soil profiles that will be mixed or removed or fill material from other areas will be introduced), the design professional should:

1. Adjust the pre-development HSG by at least one factor (i.e., HSG A to HSG B; HSG B to HSG C; HSG C to HSG D) when selecting the post-development CN. See Section 5.302 D herein; or …”

HBA of Virginia Comments:

• Post-developed adjustment is not currently required in existing VSMP Regulations, Virginia’s Stormwater Handbook, or in any guidance issued by the Department of Environmental Quality.
• Modification of the pre- to post- HSG is not possible with the Agency-provided VRRM spreadsheets.  If you do not provide matching soil area totals, the VRRM worksheet returns an error and does not compute.
• Rural areas would be particularly impacted by this provision, given that pre-development land is largely undisturbed.

3.305.2 and 3.307 (D)“Piped or channelized stormwater runoff converted to sheet flow prior to discharge should comply with 9VAC25-870-66 B (see Section 3.302 herein) and 9VAC25-870-66 C (see Section 3.303 herein) or “Safe Harbor” (see Section 3.304 herein).”

“Offsite discharges of sheet flow from a level spreader, with the exception of those discharges meeting the requirements of Safe Harbor (Section 3.304) herein, should be encompassed with a drainage easement.”

HBA of Virginia Comments: 9VAC25-870-66(D) is written such that discharges of sheet flow from level spreaders are to be treated the same as those from pervious or disconnected impervious areas, however, they are subject to different technical criteria in this guidance.  By the regulations, requirements of section 3.305.2 (A through N) should only apply when there is an increase in runoff volume or velocity compared to the pre-developed condition.  Otherwise, discharges from level spreaders should only be subject to the requirements set forth in 3.305.1 (A).

3.305.2“The length of sheet flow path to the down-gradient stormwater conveyance system should be less than or equal to the following…”

HBA of Virginia Comments: This requirement is not stated in the regulations and ignores the condition where the pre-development downstream flow path may be shallow concentrated flow or where riparian buffers are wider than the calculated sheet flow length.

3.307 “Storm drainage easements should be obtained and recorded among the local land records to encompass any proposed offsite manmade stormwater conveyance systems (including their outfall structures, such as outlet protection or level spreaders), and any proposed offsite sheet flow paths to an existing stormwater conveyance system.”

HBA of Virginia Comments:

• All discharges that are made in accordance with the Virginia Stormwater Management Act and/or VSMP Regulations and do not require/propose construction, improvement, or modification of downstream flowpaths should not be subject to obtaining offsite easements or agreements from downstream property owners.  This section should specifically exclude discharges to an existing stormwater conveyance system that is not being modified.
• As drafted, the development community would be required to obtain easements from adjacent landowners, which can be a time-consuming and unpredictable endeavor.  If adjacent landowner refuses to grant an easement, the developer has limited options available to meet requirement.

Additional Comments, Concerns, and Questions

2.303 (D)

HBA of Virginia Comments:

• This section should include meeting the channel and flood protection requirements of 9VAC25-870-66 or meeting the Safe Harbor provisions as options for compliance for sediment basin discharges in lieu of analysis of the downstream channel to the limit of analysis.  This is stated in Minimum Standard 19(n) (9VAC25-840-40).
• Creates conflict with 9VAC25?840?40 (6b): “Runoff coefficients used in runoff calculations shall correspond to a bare earth condition or those conditions expected to exist while the sediment basin is utilized.”  Guidance document proposes to eliminate the following provision: “or those conditions expected to exist while the sediment basin is utilized”

3.302.3

• HBA of Virginia Comments:
  • Creates uncertainty in determining when the more restrictive energy balance discharge requirements apply in relation to the point of discharge and the 1% limits of analysis as is done in Section 3.302.1(A)(1).  (Manmade conveyance discharging into large river example)
  • Proposed Guidance Document: “A manmade lake or reservoir not created for the purpose of managing post-development stormwater should be considered a natural stormwater conveyance system.”
    • Proposal modifies the definition of a natural conveyance system (as defined in 9VAC25-870-10); adds additional burden on development community with  minimal positive environmental benefits

3.302.3 (A) and 3.304 (C) (3)“RV_developed = the un-attenuated volume of runoff from the site in the developed condition”

HBA of Virginia Comments: Inserts the term “un-attenuated” which does not appear in 9VAC25-870-66(B)(3). This change would only serve to decrease the allowable discharge from sites and place additional burden on the development community.

3.302.4

HBA of Virginia Comments: This section appears to limit the definition of a natural conveyance system (as defined in 9VAC25-870-10) by saying flood-prone areas (included in the definition of a natural conveyance system and also specifically defined in 9VAC25-870-10) would only be evaluated for inclusion in a natural conveyance system on a case-by-case basis.

3.303

HBA of Virginia Comments:

• Proposed Guidance Document: “The applicable flood protection criteria depends on whether or not pre-development localized flooding exists downstream from the site.”

• • If 10-10 detention is acceptable when there is existing flooding, 10-10 detention should also be acceptable when there is not existing flooding. 

3.303.1 (C) (3) and 3.303.2 (B) (3)

HBA of Virginia Comments:The limits of analysis is inconsistent with the regulations, 9VAC25-870-66(C)(3)(c).  This statement should read “The stormwater conveyance system enters a mapped floodplain or other flood-prone area, adopted by ordinance, of any locality” not just a “FEMA floodplain”.

3.305.1 and 3.305.2

HBA of Virginia Comments: References to 10-yr 24-hour storm velocity are inconsistent with the current regulations.  The VSMP Regulations and all other Virginia standards evaluate erosive velocities based on the 2-yr 24-hour storm.

4.400 – 4.404

HBA of Virginia Comments: We would suggest modifying this section to be clear that demonstration of the inability to achieve compliance onsite is not a requirement for the use of offsite nutrient credits (4.404(A)).  See 9VAC25-870-69(B), which states the operators shall be allowed to utilize offsite options under certain criteria.

5.600“The design professional should screen for the relative risk of encountering acid sulfate soils within the proposed limits of clearing and grading.”

HBA of Virginia Comments: The guidance document and the website for the Virginia Tech School of Plant and Environmental Sciences is unclear whether documented sulfide occurrence triggers the requirement for a site investigation.

Thank you for the opportunity to provide comments on Guidance Memo No. 22-2012 - Stormwater Management and Erosion & Sediment Control Design Guide. I am a reviewer for Henrico County and have the following comments on this guidance memo.

• Section 3.302.1 C 3.a This section restricts post-development stormwater velocities in RCP to 10 ft/sec or less in order to be considered non-erosive. Please provide a source for this standard. What about other types of pipes? (HDPE, corrugated metal, etc).

• Section 3.303.1 C.3 “The stormwater conveyance system enters a mapped FEMA floodplain” . This contradicts VAC25-870-66 C3.c which provides an option for limits of analysis for flood protection to include mapped floodplains adopted by ordinance of a locality, not just FEMA mapped floodplains.

• Section 3.303.2 B.3 “The stormwater conveyance system enters a mapped FEMA floodplain” . This contradicts VAC25-870-66 C3.c which states an option for limits of analysis to include mapped floodplains adopted by ordinance of a locality, not just FEMA mapped floodplains.

• Section 3.305.2 D. For certain slopes in dense underbrush, the maximum length of sheet flow calculated by this equation is less than the minimum sheet flow length in DEQ Stormwater Design Specification No. 2 Sheet Flow to Filter or Open Space from the BMP clearinghouse. 

• Section 5.200 B. “Post-development drainage areas should deviate from the pre-development condition by no more than plus or minus 10%.” A “where practicable” clause would be beneficial here. For example, for some sites, there may be no existing downstream stormwater conveyance system and the more feasible option is to redirect flow to another discharge point on the site and detain to meet channel or flood protection. Or, in some cases, the downstream system is experiencing erosion or flooding and the more environmentally-friendly option would be to direct some of all of that drainage area to a different outfall that can still meet channel & flood protection.

• Section 5.303. This section provides guidance for curve numbers for a bare earth condition. However, sections 2.302.D. and Section 2.303 G both refer to runoff coefficients in Section 5.303 – can runoff coefficients for bare earth conditions (for use with the rational method) be included here as well?

Please feel free to contact me if there are any questions regarding the above comments.

Regards,

Alex Gruendl

Review Engineer

Henrico County

gru018@henrico.us