Section Env-Dw 402.06 - Treatment of Contaminants by Flow Mix(a) For the purpose of this section, "flow mix" means a treatment technique where the flow of water from one or more sources having a particular contaminant exceeding an MCL is combined with flow from one or more different sources with that contaminant below the MCL, so that the resultant flow is reliably and consistently below the MCL for that contaminant.(b) The owner of a public water system shall use flow mix as a treatment alternative only: (1) For contaminants in excess of the MCL specified in Env-Dw 703 through Env-Dw 706; and(2) In accordance with this section.(c) Before beginning the design of a flow mix treatment system, the water system owner shall: (1) Inform the department that the water system intends to use the flow mix treatment method; and(2) Submit to the department flow mix calculations based on analyses of its water sources performed within the past 6 years, or a shorter record that demonstrates consistency of quality, that include the concentration and volume ratios proposed to be used for each source that demonstrate that the criteria of (c), below, will be met.(d) The department shall approve the use of flow mix if the information submitted pursuant to (b), above, demonstrates that when the sources are combined at the correct ratio, the concentration level of the contaminant proposed to be treated by flow mixing will be reliably and consistently below the applicable MCL.(e) The equipment used to verify and document proper flow mix treatment shall include:(1) One control circuitry for all sources proposed for flow mix;(2) Flow meters installed to measure the output from each source to be used;(3) A device, such as a gate valve, on the piping from each source to allow that source's output to be regulated;(4) A gate valve for the mixture; and(5) A sample tap for each source and for the mixture.(f) The owner shall submit, on a quarterly basis:(1) Records to document the actual source flows and the calculated, concentration-weighted ratio of the mixture on a monthly calculation basis; and(2) Certification that the established flow mix ratios have been followed.(g) A water quality sample shall be taken and analyzed: (1) From each source on an annual basis; and(2) Of the mixture on a quarterly basis.N.H. Admin. Code § Env-Dw 402.06
(See Revision Note at part heading for Env-Dw 402) #10609, eff 6-1-14