Section Env-Ws 380.12 - Filtration(a) A public water system owner that uses a SW/GWUDISW, and does not meet all of the criteria in Env-Ws 380.06 and Env-Ws 380.07 for avoiding filtration, shall provide treatment consisting of both disinfection, as specified in Env-Ws 380.11, and filtration treatment which complies with the requirements of (b), (c), (d), or (e) below. Failure to meet any requirement of this section shall be a treatment technique violation.(b) For a public water system owner using conventional filtration or direct filtration, the turbidity level of representative samples of a system's filtered water shall be less than or equal to 0.5 NTU in at least 95% of the measurements taken each month. The turbidity level of representative samples of a system's filtered water shall not exceed 5 NTU.(c) For asystems using slow sand filtration, the turbidity level of representative samples of a system's filtered water shall be less than or equal to 1 NTU in at least 95 percent of the measurements taken each month. The turbidity level of representative samples of a system's filtered water shall at no time exceed 5 NTU.(d) For asystems using diatomaceous earth filtration, the turbidity level of representative samples of a system's filtered water shall be less than or equal to 1 NTU in at least 95 percent of the measurements taken each month. The turbidity level of representative samples of a system's filtered water shall at no time exceed 5 NTU.(e) The owner of a public water system may use a filtration technology not listed in (b) through (d) above if the owner demonstrates to the department, using pilot plant studies, that: (1) The alternate filtration technology, in combination with disinfection treatment that meets the requirements of Env-Ws 380.11, consistently achieves 99.9% removal of giardia lamblia, inactivation of giardia lamblia cysts, or both; and(2) The treatment removes 99.99% of viruses, inactivates viruses, or both.(f) For a system that demonstrates the requirements in (e) above, the requirements in (c) above shall apply.(g) The owner of a system serving at least 10,000 people shall meet:(1) The requirements for other filtration technologies set forth in Env-Ws 380.23; and(2) The turbidity requirements set forth in Env-Ws 380.27.(h) As required by 40 CFR 141.70(a)(4), beginning January 1, 2005, the owner of a public water system serving fewer than 10,000 people shall comply with the requirements listed in (g), above.N.H. Code Admin. R. Env-Ws 380.12
#5098, eff 3-18-91, EXPIRED 3-18-97
New. #6521, eff 6-4-97 (See Revision Note at chapter heading for Env-Ws 300); ss by #8352, eff 5-14-05 (formerly Env-Ws 380.20 )