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