§ 109.605. Minimum treatment design standards.
The level of treatment required for raw water depends upon the characteristics of the raw water, the nature of the public water system and the likelihood of contamination. The following minimum treatment design standards apply to new facilities and major changes to existing facilities:
(1) For surface water and GUDI sources, the minimum treatment design standard for filtration technologies is a 99% removal of Giardia cysts, and a 99% removal of Crytosporidium oocycsts. The determination of the appropriate filtration technology to be used shall be based on the following:
(i) Conventional filtration designed and operated in accordance with standards established in the Department’s Public Water Supply Manual can be expected to achieve the minimum treatment design standard and shall be considered the best treatment for most surface water sources in this Commonwealth because of the multiple barriers of protection that it provides.
(ii) Direct filtration, slow sand filtration and diatomaceous earth filtration may be permitted if studies, including pilot studies where appropriate, approved by the Department are conducted and demonstrate, through achievement of the turbidity performance standards specified in § 109.202(c)(1)(i) (relating to State MCLs, MRDLs and treatment technique requirements), that the minimum treatment design standard can be achieved consistently, reliably and practically under appropriate design and operating conditions.
(iii) Other filtration technologies may be permitted after onsite studies, including pilot plant studies where appropriate, using seeded indicator organisms in the raw water or other equivalent means as approved by the Department, that demonstrate that the technology can consistently achieve the minimum treatment design standard.
(2) For surface water and GUDI sources, the minimum treatment design standard for disinfection technologies utilized prior to the first user of the system is a total of 99.9% inactivation of Giardia cysts and a 99.99% inactivation of viruses, except noncommunity water systems may propose, and the Department may approve, an alternative to the Giardia design standard when 99.9% inactivation is not feasible. Total treatment system disinfection capability will be credited toward this design standard. The CT factors and measurement methods established by the EPA are the criteria to be used in determining compliance with this minimum treatment design standard.
(3) For surface water and GUDI sources permitted after December 26, 2009, that are determined to be bin 2 or higher, the minimum treatment design for filtration and disinfection must also meet the requirements of § § 109.1203 and 109.1204 (relating to bin classification and treatment technique requirements; and requirements for microbial toolbox components).
(4) For community water systems using groundwater, the minimum treatment design standard for disinfection technologies utilized at the entry point is a total of 99.99% treatment of viruses.
(5) For noncommunity water systems using groundwater with an E. coli-positive groundwater source sample collected under § 109.505(a)(3) (relating to requirements for noncommunity water systems), the minimum treatment design standard for disinfection technologies utilized at the entry point is a total of 99.99% treatment of viruses.
Source The provisions of this § 109.605 adopted December 7, 1984, effective December 8, 1984, 14 Pa.B. 4479; amended March 24, 1989, effective March 25, 1989, 19 Pa.B. 1289; amended May 15, 1992, effective May 16, 1992, 22 Pa.B. 2621; amended July 20, 2001, effective July 21, 2001, 31 Pa.B. 3895 and 3938; amended May 22, 2009, effective May 23, 2009, 39 Pa.B. 2661; corrected August 29, 2009, effective August 1, 2009, 39 Pa.B. 5119; amended December 24, 2009, effective December 26, 2009, 39 Pa.B. 7279. Immediately preceding text appears at serial pages (345337) to (345338).
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