2019-05-24_PERMIT FILE - M2019027 (2)

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Environmental Impacts of Water Treatment Chemicals at Industrial Sand Mines C-39 BARR This compound has been safely used for decades in the is classified by the U.S. Environmental Protection Agency United States to treat public drinking water. Polyacryl- (EPA) as a B2, a probable human carcinogen.'There are amide also is widely used in a variety of industries and no negative health effects associated with the actual can be found at food processing facilities, used as blast- polyacrylamide flocculant itself; only the acrylamide ing agents, used for drilling mud and grout products, and monomer used as a soil-stabilization agent. Because of this classification and its common use as a Acrylamide is a monomer used in the production of the settling agent, or flocculant, at municipal drinking water anionic polyacrylamide flocculant. It is not a breakdown treatment plants,the EPA has established a National or daughter product of polyacrylamide. A small amount Primary Drinking Water Regulation (NPDWR)for acryl- of residual, unreacted acrylamide monomer remains in amide. This NPDWR established the de facto limit of the polyacrylamide flocculant as an impurity when it is 0.5 micrograms per liter(ug/L)for acrylamide through a added to the wash process. treatment technology standard.This standard is based PolyDADMAC cationic coagulants are commonly used to on a maximum concentration of acrylamide monomer in enhance the performance of the belt press associated commercial polyacrylamide flocculant (500 ppm) and a with wash plants. This compound is also widely used in maximum dosing concentration of flocculants (1.0 ppm) the United States to treat public drinking water. DADMAC directly to potable water. While the EPA has approved is a monomer used in the production of the cationic laboratory methods for acrylamide, Barr has found no polyDADMAC coagulant. laboratory able and willing to perform the procedure on process wastewater. Barr has identified at least one These products serve a significant benefit to the op- laboratory that can measure acrylamide monomer con- eration of a mine site because they reduce the overall centrations near these low concentrations (less than 1 footprint of the mine,which would otherwise require ug/L) using a non-EPA approved method. extensive settling basins. In some cases, these settling b This paper addresses uses typical of polyacrylamide at basins can result in additional costs related to water management and berm construction. mine sites and related processing facilities. However, it is appropriate to note that polyacrylamide can be highly Both of these compounds are readily biodegradable and toxic to aquatic life if discharged directly into surface wa- monitoring at frac sand mines in the Midwest indicate ter habitats. Although this type of discharge is not typi- that there is no evidence of groundwater contamina- cal of the mine site processing, any potential discharge lion associated with either of these compounds.This involving unreacted polyacrylamide entering surface paper provides additional background on each of these water should be avoided. chemicals and a detailed analysis of the fate of these compounds using a kinetic model that includes biodegra- Unlike the acrylamide monomer, the DADMAC monomer dation and other chemical processes. has not been linked to adverse health effects. DADMAC has no NPDWR and no secondary standards, nor has it regulatory background been designated by the EPA as a Contaminate of Concern Although no adverse human health effects are associ- in CCL1 (Contaminate of Concern List 1), CCL2 or CCL3.' ated with the polyacrylamide polymer, adverse human Furthermore,there are no EPA or MPCA surface water health effects have been linked to an impurity called standards for DADMAC, nor has the Minnesota Depart- acrylamide, which is a monomer, or part of the poly- ment of Health or the Wisconsin Department of Natu- acrylamide molecule used in the production of the ral Resources established health-risk limits.The water anionic polyacrylamide flocculant. A very small amount of the monomer molecule is present in the raw chemical feedstock that remains unreacted in the polyacrylamidewww.epa.gov/chemfact/s—acryla.txt flocculant when it is mixed in the wash process used in the mine's wet plant. 2 EPA. 2012.Basic Information on CCL and Regulatory Determinations. http://water.epa.gov/scitech/drinkingwater/ It is this acrylamide monomer(not polyacrylamide) that dws/ccl/basicinformation.cfm Page 2 © Barr Engineering Co.2013 Keenesburg Project—Limited Impact 110 Application_May 24,2019