Stantec sincerely appreciates the opportunity to review the draft guidance document, and we remain supportive of Department’s effort of providing a comprehensive reference. Based on review of the latest release; however, it appears that limited changes have been made to Draft Guidance Memo No. 22-2012. Stantec staff have noted several questions and concerns that remain with the guidance as proposed.
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. While not comprehensive, an itemization of specific comments is included under Attachment A for consideration. We look forward to continued discussion and working together with DEQ, and fruitful dialogue under eventual guidance implementation.
Attachment A - Comments on Guidance Memo No. 22-2012 - Stormwater Management and Erosion & Sediment Control Design Guide
| Comment # | Guidance Section | Comment |
| 1 | Summary | It is unclear from the summary if the guidance is intended to be applied to Annual Standards and Specifications holders and projects. |
| 2 | 2.200 | There is quite a bit of uncertainty surrounding the language. The guidance states that, “Nothing contained herein shall be deemed to waive or modify other requirements of existing law or regulations,” but the language and tone of the guidance document would seem to be inconsistent with this statement. In one instance the document indicates this is “preferred guidelines” for ensuring compliance, other sections indicate land development “is subject to” the guidance, yet other areas of the document indicate that the Authority “may allow for variations” to the guidelines or may allow for “exceptions” to the guidelines, and yet other sections refer to this as the “minimum acceptable”. Given that the guidance extrapolates quite significantly from standard engineering practice for stormwater over the past 8 years, modifies the current technical guidance, and infers several requirements which are not stated in the guidance, the language above does not jibe with the disclaimer language that indicates that alternative proposals are to be reviewed or denied based on technical adequacy and compliance with the regulations, and that this does not mandate or prohibit any action not already mandated or prohibited by the law and regulations. It is very clear that projects will be reviewed for strict adherence to this guidance, and that administrative action is required to vary from it or to take exception to it. |
| 3 | 2.303.D.2 | This criteria applies post-construction stormwater quantity criteria to temporary construction sediment basin releases. Post-construction regulations specifically indicate that post-development numbers are based on ultimate build-out, not temporary conditions. |
| 4 | 3.302.1.C.3* | Asterisk – It appears advisable to perform case studies / scenarios to confirm this criteria doesn't unduly, or double, penalize highly erodible soils. It would seem that highly erodible is largely related to slope, and slope is already accounted for in the permissible velocities cited above. |
| 5 | 3.302.4 | This section is inconsistent with the definitions above. The flood-prone area is the area outside of the main channel This obviates the entire purpose for creating definitions of conveyance systems (instead of just channels). This section effectively requires definition of the floodprone area with a storm that likely never leaves the main channel (the 1-yr). Additionally, as written it would appear that all outfalls would need to be reviewed and approved by DEQ, regardless of the applicability of GM22-2011 (streamlined review). Further, this section could encourage additional impacts to wetland fringe areas adjacent to the main channels, which would may result in an adverse environmental impact. |
| 6 | 3.303 | Localized flooding is only defined as flood conditions which are likely to cause property damage or unsafe conditions. The reason for the definitions of the conveyance systems themselves were to be permissive of small amounts of additional flooding where it was not injurious to property. |
| 7 | 3.303.D | This doesn't appear to be sound universal criteria. There are many new culverts with design HW elevations higher than the channel during a 10-year event. |
| 8 | 5.302.D | 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. |
| 9 | 3.307.D | This effectively invalidates the purpose and viability of the sheet flow requirements that were intentionally embodied in the regulations, and is inconsistent with the goal of maintaining pre-development drainage areas. |
| 10 | 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. There were several regulatory meetings and discussions to not mandate ESD like this guidance document effectively implies. The simplicity and elegance of the VRRM/EB is that it rewards ESD and encourages it, without mandating ESD to the maximum extent practicable. |
| 11 | 5.302.D | Without discussing the applicability of this criteria, or providing nuance and context, the proposed requirement is a sweeping change from current practice, deviates from the basis of the regulations, and will potentially result in a greater increase to stormwater facility sizes that the regulations themselves did when adopted. There are certainly instances where massive changes to the soil strata may warrant this consideration; however, that would deviate from longstanding stormwater practices and numerous hydrologic validation studies. The options for dealing with the matter effectively resolve to 1 or 5. Option 2 appears to be excessively costly and Items 3 and 4 area generally impracticable due to the need to revise plans after construction. Item 5 could be expanded upon and could involve deep ripping or tilling, strip, segregate, stockpile and re-application of in-situ topsoil, or other more practical and cost-effective means of dealing with the underlying issue. |
| 12 | 5.302.E | This will have implications on water quality too. Water quantity and water quantity were deliberate equiavalated when the regulations and technical criterion were developed. This will require updates to the VRRM spreadsheets. Further, see our forest/open space comment. |
| 13 | 5.302.E | Forest cover and open space were defined as hydrologically equivalent during the development of the regulations and the methodology and this was deliberate. When the regulations and technical framework (VRRM/Energy Balance methods) were developed, there was a deliberate decision to draw equivalence between forest and unmanaged pervious open space (such as utility easements). The reasons were several, but include, in part: • The near equivalence of forest and open space in terms of curve number. • The added complexity of bifurcating forest and open space, which would affect both quantity and quality computations (both are based on runoff volumes, either on an event basis or annual basis, respectively). • The inability of an easement holder to control the overall drainage patterns and infrastructure on privately-owned property through which a utility traverses. • The impracticality of servicing new or expanded vegetated linear easements with stormwater practices. • Related to the above point, during the development of the regulations, based on discussions with many stakeholders, it was not deemed desirable to the Commonwealth, landowners and utility entities to force structural stormwater facilities treating meadows and woods in a vegetated utility corridor. It is further likely to be very costly and provide no measurable environmental benefit (and expanded land disturbance). Based on the above, when the regulations were adopted, the Commonwealth elected to employ a compliance framework which assured that vegetated open space areas meeting the Forest and Open Space Management conditions be deemed effectively equivalent from a water quality and quantity standpoint. As such, these landuses remain computationally equivalent under current VRRM. These conditions generally set forth that the entity mow or maintain the areas no more than four times per annum, and have a maintenance plan consistent with these criterion. Suggest striking this table, or use the CN values that are consistent with the VRRM categories (three categories, not four). |
| 14 | 5.500 | The language requires “compliance” with a handbook that is not referenced in the regulation. |
| 15 | 7.400 | Why is DEQ requiring as-built drawings for storm sewers and culverts? The regulations require construction record drawings for permanent stormwater management facilities only. Additionally, we suggest avoiding the use of the term (as-built drawing) as it was intentionally avoided during the regulatory process. |