2024-06-07_PERMIT FILE - M2024026 (23)

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Environmental Impacts of Water Treatment Chemicals at Industrial Sand Mines BARR fate of PoIyDADMAC in the soil and groundwater beneath them. PoIyDADMAC cationic coagulants are commonly used to enhance the performance of the belt press associ Because DADMAC carries no known human health con- ated with wash plants. This compound is also widely cerns,there is less published data and little risk analysis used in the United States to treat public drinking water. concerning its fate in the environment. We have not DAD MAC is a monomer used in the production of the been able to locate sufficient information on DADMAC cationic polyDADMAC coagulant. A small amount of to derive steady-state concentrations of the compound residual, unreacted DADMAC monomer remains in the as we were for acrylamide. However, given the evidence polyDADMAC coagulant when it is added to the process. that it is highly biodegradable, it is assumed that if acryl The differences between the DADMAC and acrylamide amide degrades rapidly than the same conditions would monomers and the fate of residual DADMAC monomer result in similar performance from DADMAC monomer. in the environment are discussed later in this document. analytical methods and The DADMAC monomer is soluble in water, biodegrad monitoring requirements There are no practical, EPA-approved laboratory meth- able under aerobic conditions, and has poor adsorption ods for monitoring of acrylamide or DAD MAC.The EPA, to minerals and organic matter.1°Because of its solubil through a treatment technology standard, limits the ity and its inability to adsorb to solids,the water phase amount of anionic polyacrylamide used at water treat- concentration of the DADMAC monomer in the filtrate ment plants by limiting the amount of the monomer produced by the belt press will equal the concentration in flocculants to less than 500 parts per million (ppm) within the process water that overflows the clarifier and acrylamide, used at a concentration of 1.0 ppm or less. is recycled in the wash loop. This gives a de facto safe drinking water limit of 0.5 ug/L. Like acrylamide, the DADMAC monomer is considered The EPA has established no treatment standards for DAD- readily biodegradable. The acrylamide monomer has a MAC. NSF 60 has established an allowable concentration shorter half-life than DADMAC(approximately one day in drinking water of 50 ug/L,or 100 times higher than vs. 15 days for DADMAC). Neither monomer is consid- the de facto standard for acrylamide. ered bioacculmative. Both monomers are considered to ALS-Columbia Laboratory in Kelso, Washington, has de- have low environmental toxicity. veloped a practical, non-EPA-approved analysis method Because the DADMAC monomer is readily biodegradable for acrylamide. It uses liquid chromatography tandem in water, it will achieve a steady-state concentration in mass spectrometry (LC-MS/MS)technology and has a the clarifier/sand wash loop. Due to its higher monomer minimum detection limit at or below the EPA's limit of concentration and longer half-life, it is expected to have 0.5/ug/L. a higher steady state concentration than acrylamide. It ATSDR study is important to note that there are no published recom- In 2008,The U.S. Department of Health and Human mended or regulatory standard for DAD MAC. Given the Services' Agency for Toxic Substances and Disease Reg- relatively small volume of polyDADMAC used at most istry(ATSDR) published a Health Consultation regarding facilities(in comparison to polyacrylamide) and the potential environmental exposures to acylamide from relatively small concentration of DADMAC monomer,the the on-site disposal of sand fine sludge and wash water expected steady-state concentration is expected to be from the Belvidere Sand &Gravel (BS&G) site in Warren relatively low (less than 1mg/L). County, New Jersey. BS&G uses a polyacrylamide floc- Since DADMAC readily breaks down in soil and water, culant in their closed loop aggregate washing process, biodegradation should occur in the sand piles as well as similar to those used by the Industrial Sand industry. 10 EPA.2004.Test Plan for DADMAC.http://www.epa. Petitioners expressed concern about potential con- gov/hpv/pubs/summaries/dialdime/c15208t12.pdf tamination of potable wells by acrylamide and resulting Page 5