Viriginia previously provided guidance for the use of flocculants such as anionic polyacrylamide for treating turbid stormwater on site prior to discharging but there does not appear to be any mention of this treatment technology in the new permit. Given the new, stricter turbidity limits, practitioners will need tools and guidance on how to achieve the new turbidity mandates. The EPA's Construction General Permit provides language on what types of flocculants are allowed in the passive treatment of construction stormwater and dictates eco-toxicity standards for using food grade/ drinking water treatment chemicals.  It also provides guidance on how to test soil types prior to the application of these treatments to make sure the products applied are suitable for flocculating the soil type to which they are applied. Consider adopting language from the EPA's CGP to provide guidance to erosion and sediment control practitioners in Virginia.

Regulation and guidance that limits the discharge of sediment from construction activities is vital to maintain the health of our nation's water resources.  Equally important is providing permittees the tools needed to meet those limits.  As the Permit is currently written, in conjunction with details provided in Virginia’s Erosion and Sediment Control Handbook, there is not sufficient information and guidance to allow these criteria to be met in certain cases.

Traditional, physical BMPs are ineffective at capturing, filtering, or settling fine particles such as clay, silt, and even fine sand (1, 2, 3, 4).  Therefore, many states as well as the Federal 2022 CGP have included flocculants/ chemical treatment as a standard tool to enhance traditional BMPs to tackle small soil particles (1,2,3,4).  In addition, for chemicals treatments/ flocculants to be used safely and effectively, guidance is needed on the type of chemical, chemical characteristics, amounts, and specific uses that are allowed.  Almost all states allow chemical treatment in some capacity (3) and over 25 states have included guidance (DOT, environmental agencies, permits, handbooks, etc.). VA DEQ had previously provided a detailed Technical Bulletin for Anionic Polyacrylamide use (aPAM).  The document is still being referenced but has since been removed. 

Providing guidance on flocculants and how they can be used to meet the new proposed numeric turbidity limits should be included in the proposed permit to ensure permittees are able to meet the limits and maintain compliance.

References:

(1) https://www.epa.gov/system/files/documents/2021-11/bmp-treatment-chemicals-for-particulate-removal-from-construction-stormwater.pdf

(2) https://mdl.mndot.gov/index.php/items/201425

(3) https://www.owp.csus.edu/research/passive-dose/passive-chemical-treatment.pdf

(4) https://etd.auburn.edu/handle/10415/8213

I work with engineers and erosion control professionals in Virginia. Many have expressed concern with meeting the proposed numeric dewatering discharge turbidity limits. The expressed concern is that they have a numeric discharge limit to meet but have no tools or direction as to how to meet these discharge limits. I am a proponent of environmental conservation and believe limits are needed and necessary as sediment is a significant pollutant and should not be discharged. Guidance should be provided in the permit for those conducting dewatering projects in VA on how to meet low numeric discharge limits. 

Suggest providing options for folks to reduce turbidity since achieving 50 NTU or lower will require chemical treatment (or possibly filtration although not usually practical). NCDOT has a useful guidance doc found at https://connect.ncdot.gov/resources/hydro/HSPDocuments/Appendices.pdf

I recently became aware of updates to Virginia's SWPPP requirements.  Upon reviewing turbidity requirements for dewatering discharges, I was unable to find how the State suggests obtaining values of 10 NTUs or 50 NTUs.   

My professional experience indicates only two methods can achieve 10 NTUs or 50 NTUs, namely, retain all discharge waters or make use of flocculants. The former requires use of professionally designed containment systems.  Unfortunately, the latter does not appear in the State's updates as an acceptable mitigation method.   I strongly suggest you add the use of flocculants to be an acceptable method to achieve desired turbidity values for dewatering discharges activities. 

The Virginia Transportation Construction Alliance, representing nearly 300 transportation contractors, engineers, aggregate producers and supporting industries, appreciates the opportunity to provide comments on DEQ’s proposed 2024 Amendment and Reissuance of The Existing General Permit Regulation (9 VAC 25-880).

The Alliance has the following comments and concerns regarding the proposed dewatering monitoring regulatory language.

• The proposed instantaneous or daily turbidity benchmarks significantly exceed the EPA's established weekly average benchmarks and believe that the technical feasibility to meet the proposed turbidity benchmarks is not likely to be achieved on roadway construction projects without extensive, costly, and impractical control methods.  It is recommended that the Department establish consistency with EPA and several other states that have successfully implemented a higher weekly benchmark and a more practical daily average benchmark.
• Turbidity sampling at the dewatering point appears to be required regardless of distance from the dewatering location to the discharge location.  Since discharge locations could include upland areas where the water may never reach a given tributary, sampling should only be required at the discharge point to a jurisdictional tributary, not at the dewatering location.  This should be clarified in the proposed regulations.
• Achieving the benchmark will require the use of more extensive dewatering “structures” on construction sites.  The structures will need more space to be placed and operate requiring additional easements unnecessarily impacting land that would otherwise be left undisturbed.
• The proposed language adds all surface waters within the Chesapeake Bay watershed, which includes all wetlands, intermittent and ephemeral streams.  These features will be difficult, and perhaps non-existent, to obtain “upstream” grab samples as required to assess baseline conditions and should be excluded from the proposed regulation.
• As written, achieving compliance on construction projects with dewatering needs would impose significant time and economic burden on maintaining and improving the Commonwealth’s transportation system.  It is likely that the daily monitoring and daily threshold limit would lead to frequent work stoppage and significant, costly project delays.

The members of the Virginia Transportation Construction Alliance understand and are committed to protecting the environment as we deliver the transportation needs of Virginians.  Although a Technical Advisory Group was established to support development of the proposed changes, we believe that the proposed construction dewatering requirements fall short in technical feasibility, practicality, and economic impact.  We recommend that additional discussion with DEQ and industry partners be held to identify an efficient and practical balance to protect Virginia’s waters.  We look forward to being a part of those discussions.