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Reference: Draft Guidance Memo No. 22-2012 - Stormwater Management and Erosion & Sediment Control Design Guide
Stantec sincerely appreciates the opportunity to review the draft guidance document, and we are encouraged by the Department’s apparent goal of providing a comprehensive reference.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.
| Comment # | Guidance Section | Comment |
| 1 | General | It is implied throughout the Guidance that the standards within relate to minimum levels of acceptable plans. This would appear to have broader application than just plans reviewed by DEQ which could cause confusion amongst other plan review authorities. In general, the criterion sets enhanced standards for compliance than would be found in most jurisdictions in the state. |
| 2 | General | Consideration should be given to the phasing of implementation generally speaking for new or clarified recommendations under this guidance, particularly as they relate to projects that are currently in design and/or permitting. |
| 3 | General | The guidance appears to contain both language relating to existing requirements (sometimes slightly modified language from current adopted regulations) alongside some new elements or criteria that are recommended. While we believe the intention is to provide one comprehensive resource and appreciate that approach, we have concerns that reciting current established regulation that appear on equal footing with other practices or recommendations may have varying degrees of, or limited, regulatory structure or formal basis to date in the Commonwealth. |
| 4 | 1.100 | The final sentence in this section implies broad programmatic applicability and appears to extend beyond only DEQ's review. |
| 5 | 1.200 | DEQ involvement in the cover sheet of an approved set of plans (discussed later in the Guidance) implies that exceptions have been granted. |
| 6 | Chapter 2.000 | Generally, this chapter appears to be a regurgitation of the existing VESCP regulations / Virginia Erosion and Sediment Control Handbook. Consider consolidating to guidance based on the existing standards. |
| 7 | 2.100 | The purpose statement appears to be borrowed from the regulations and discusses the establishment of acceptable erosion and sediment control (ESC) guidelines. Consider amending to discuss that the items are clarifications and current Agency interpretations. |
| 8 | 2.200 | This section states "Nothing contained herein shall be deemed to waive or modify other requirements of existing laws or regulations." However, several criteria appear to modify the requirements of the regulations. |
| 9 | 2.200 | The last sentence in this section discusses "variations", is the intent here to state "variances" as described in the regulations? Would localities have to grant variances from any criterion in this document, given the prior section implies that this doesn’t apply to them? |
| 10 | 2.300 | Does the phrase "at the time of initial plan acceptance" imply that the criteria only applies to plans which have not been accepted for review prior to their being finalized? |
| 11 | 2.304.B | This provision should start with "Where feasible,". |
| 12 | 2.306.C & 2036.E | Given the apparent importance on compaction within the guidance, it appears additional definition of what might constitute a reasonable compaction level for appropriate topsoil uniform placement/distribution (Section C) versus compacting "enough to ensure good contact with the underlying subsoil" (Section E) versus "undue compaction" (Section E). |
| 3.200 | The language, as expressed, seems to indicate that an “exception” may be allowed by DEQ. We envision a fairly routine number of instances where designers can comply with the regulations (shall), but not the additional criteria DEQ is adding (should), and envision this will be very cumbersome to administer and receive approvals in those instances. | |
| 13 | 3.303.1.C.3 & 3.303.2.B.3 | Potential unintended conflict due to language re-citation / modifications from adopted regulation - The definition of limits of analysis should align with 9VAC25-870-66.C.3.c. |
| 14 | 3.303.2.3 | Regulation - "Natural stormwater conveyance system" means the main channel of a natural stream and the flood-prone area adjacent to the main channel; ..." Guidance Language - “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. We believe the language (second guidance sentence) was provided to indicate more detailed understanding of DEQ's interpretation of the "Natural stormwater conveyance system" as defined under the regulations - and is appreciated. However, the language does deviate from (or is supplemental to) the regulatory language, and could lend to definition confusion. Suggestion: In instances like this were certain DEQ interpretation language is additive for clarity, perhaps it would be beneficial to set off the new guidance language under a separate heading or subsection similar to "DEQ Understanding / Interpretation". |
| 15 | 3.302.3.D | For designer clarity and to potentially reduce DEQ's review burden, it's suggested that the guidance provide for an alternate methodology criterion that gives some flexibility from the improvement factor for applicants use in demonstrating conformance with issues such as those identified in DEQ Guidance Memo No. 15-2003 Postdevelopment Stormwater Management Implementation Guidance for Linear Utility Projects under the Virginia Stormwater Management Program Regulation, 9VAC25-870. "If the project will not result in significant changes to the predevelopment runoff characteristics of the land surface after the completion of construction and final stabilization", this may afford an opportunity to clarify methodologies that may be acceptable to DEQ. For example, several AS&S holder have standards that if they are restoring pre-development conditions within an easement, they generally do not apply water quantity BMPs or an Improvement Factor (IF). Without the alternate methodology approved by DEQ, a de-facto improvement factor would be required on quantity neutral sites where there is no practicable means to control runoff (example a sewer easement under a shopping center parking lot, etc.). The addition of an alternate method may provide for a more streamlined and understood demonstration. |
| 16 | 3.302.4.A | This section appears to diverge from the definitions under current regulations and appears to comingle channel protection criteria (small storms) with flood protection criteria (10-year). A 1-year storm is on the order of a small frequent storm event, which would be contained in the "Main channel". A 1-yr storm is likely below a channel forming or bankfull event and more than likely would not exceed the limits of the main channel nor access the flood-prone area. By definition, Localized Flooding occurs outside the stormwater conveyance system, of which the floodprone area is a part. Perhaps this is best dealt with two distinct Department clarifications, one regarding placement / acceptance of stormwater outfalls (or limitations based on constraints) and their relation to the stormwater conveyance system (channel protection) and a separate clarification specific to flood protection. |
| 17 | 3.303.4.B | We believe this language is intended to draw a distinct line what constitutes localized flooding, and this is appreciated. Although, the section introduces the undefined phrase "Open stormwater conveyance channel" which may get confused or conflict with the defined regulatory phrase "Stormwater conveyance system". Second, we suggest a clarification - The phrase "higher than the bank of the channel" may imply only the "main channel", which is already defined under current regulation. Encouraging containment of a 10-year storm event within the main channel of a natural system is not likely advisable. The floodprone area should remain part of the natural stormwater conveyance system. Based on the standard as written, all natural stream systems in the Commonwealth experience localized flooding, except for the most degraded, incised channels. The expansive definition for the conveyance system was intended to allow for discharges at a flood fringe rather than requiring channelization through (often wetland prone) floodplains. |
| 18 | 3.305.1 & 3.305.2 | These sections appear to adopt an erosivity standard for the 10-year storm event, which is generally reviewed against a 2-year storm event. We are uncertain as to the regulatory basis for this. |
| 19 | 3.305.2.G | We recommend adding language clarifying that the use of DEQ Stormwater Design Specification No. 4 (Soil Compost Amendment) should only be necessary as part of the water quality compliance approach (crediting BMP). Applicants should have other acceptable means of returning disturbed areas to a hydrologically functional condition outside of strict adherence to Specification No. 4. Further, "full implementation" of Specification No. 4, would require potentially overly burdensome aspects, including maintenance activities, agreements, easements, etc. |
| 20 | 3.305.1.B.2 | This standard appears extremely conservative, and it should be noted that sheet flow segment times of concentration are calculated using 2-yr rainfall depths per Chapter 3 Technical Release 55 Urban Hydrology for Small Watersheds. |
| 21 | 3.305.2.D | The length of sheet flow, while conservative for time of concentration computation, do not marry well with observed conditions in many areas of Virginia. We envision this restrictive criteria to result in more channelization of discharges and less maintenance of pre-development hydrologic patterns. |
| 22 | 3.307.A & 3.307.B | Uncertain of the 16 feet easement width origin. Easements may be subject to special issues, conditions, or constraints. Importantly, this may conflict with local guidance or ordinance in some instances. |
| 23 | 3.307.C | The ultimate holder of the easement or maintainer of the utility should determine the minimum easement width. We see no role for DEQ in this unless DEQ holds such easements. |
| 24 | 4.301.D | Uncertain as the need for this statement. Generally, the regulations and by extension this guidance would be subject to change. |
| 25 | 4.400 | Environmental Site Design (ESD) is certainly encouraged; however, there are many instances where the process does not apply and is not required to achieve compliance with current regulations. The section implies that reviewers may request a demonstration of ESD steps that have been taken on a given project, which may lead to additional review iterations and potential for schedule impacts with no tangible environmental benefit in many cases. |
| 26 | 4.404.A | This section may imply or suggest that only after demonstration of an ESD process and / or the inability to achieve onsite water quality compliance may an applicant use offsite compliance options, whereas 4.404.B is a requirement - operators shall be allowed to utilize offsite options under certain specific regulatory criteria. |
| 27 | 5.200.B | Holding pre/post drainage areas to +/-10% may be aspirational, but it is impractical for a number of sites or project types. Designers should have as many tools in the toolbox as possible for compliance with current regulatory requirements, tailored to the specific needs, constraints, and opportunities of a given project. |
| 28 | 5.301.D | It may be advisable to provide clarification or additional definition as to what constitutes "previously disturbed soils". Would landuses such as silviculture or agriculture fall into this category? |
| 29 | 5.301.D | The curve number adjustment may result in improved incentivization for site selection in some instances. However, these sections appear to be enough of a departure from traditional practice and regulation in Virginia that additional stakeholder vetting, case study development, or policy consideration may be advisable for consistent and effective implementation. Specific to 5.301.D.1 - Wholesale adjustment of the HSG category - the concern is there may be some administrative, accounting (such as VRRM, or duplicative reporting), or other procedural consequences that could be unintended and that might not lead to positive environmental outcomes. Further, this may directly increase project development study, timelines, and cost with no clearly established requirement. |
| 30 | 5.302.D.2 | Many permittees have long-standing, well established processes and procedures for restoration areas of disturbance, which DEQ has reviewed and approved prior and which should remain available. Applicants should not be in effect required to achieve full compliance with a water quality specification. This may be overly burdensome to achieving appropriate soil restoration and positive environmental outcomes. This may be particularly true for routine infrastructure maintenance or other exempt activities. Additional remediation options (or pathways for those options) should be provided. Such options might include those solely involving mechanical decompaction methods (i.e. tilling / ripping) to restore / decompact disturbed soils and usage of approved minimum standards for topsoiling. The full implementation of DEQ Stormwater Design Specification No. 4 would appear to be one avenue forward that would provide water quality benefit however, that should not be a requirement when it comes to restoring soils to functional hydrologic condition. |
| 31 | 5.302.D.1 | "See Section 5.302 D herein; or" appears to be a circular reference. |
| 32 | 5.302.D (*E) | Forest cover and open space were defined as hydrologically equivalent during the development of the regulations and the methodology and this was deliberate. The numbers are so similar that the general consensus on the TAC was that no additional land use categories to be included in the compliance methodology. Suggest striking this table, or use the CN values that are consistent with the VRRM categories (three categories, not four). |