Agenda - Council Work Session - 10/20/2020 - Special

Home

3.3.1 3.3.2 34 3.4.1 3.4.2 Iron The secondary standard for iron is 0.3 mg/L where iron concentrations above the secondary standard can ause a rusty color to the water, sediment build-up, a metallic taste, and reddish or orange staining. As shown on Table 2, the drinking water from the Ramsey wells consistently exceeds the Secondary Standard for iron with concentrations ranging from 0.240 mg/L to 0.818 mg/L Hardness Hardness, which is a measurement of multivalent cations, such as calcium and magnesium, is an aesthetic issue due to its ability to cause scaling and build-up on fixtures, as well as its reaction with soaps producing a sticky and gummy deposit. Although not included as a secondary standard, water with a hardness above 120 mg/L as CaCO3 is considered hard water. As shown on Table 2, the drinking water from Ramseys wells is considered hard with a hardness ranging from 211 mg/L to 280 mg/L. Emerging Contaminants The US EPA uses the Contaminant Candidate List (CCL) and the Unregulated Contaminant Monitoring Rule (UCMR) to screen potential contaminants for further regulation. The CCL and UCMR are discussed in the following sections. Contaminant Candidate List The US EPA maintains a Contaminant Candidate List (CCL) for contaminants that may need to be regulated, which is published every five years. The current CCL includes 97 chemicals or chemical groups and 12 microbiological contaminants, and can be seen in Appendix C along with the other published CCLs. The list includes chemicals used in commerce, pesticides, biological toxins, disinfection byproducts, and waterborne pathogens. The contaminants on the list are not currently regulated by existing Primary drinking water standards. It should also be noted that the US EPA reviews existing regulated contaminants. If existing standards are modified, they are typically lowered (i.e. arsenic) and not raised. Unregulated Contaminant Monitoring Rule Along with the CCL, UCMR is used by the EPA to collect data for contaminants that are suspected to be present in drinking water, but do not have health -based standards set under SDWA. Occurrence data are then used to determine whether particular contaminants should be regulated in the interest of protecting public health. Monitoring under UCMR is conducted every five years for no more than 30 contaminants, and is required for all community water systems over 10,000 people, and for a representative sample of systems with populations less than or equal to 10,000 people. Selection of contaminants to be monitored is determined through existing prioritization processes, including contaminants previously monitored under UCMR, and the CCL. Other contaminants of interest may also be chosen. Since the promulgation of UCMR, there have been four rounds of sampling with the fourth round (UCIV1R4) currently underway. Among the four rounds of UCMR sampling, some of the contaminants include: • Pesticides • Volatile Organic Compounds (VOCs) FEASIBILITY STUDY -DRAFT RAMSY 154354 Page 11