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.