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)