General Design Criteria -- Developed in 1990, these general design criteria for surface water and groundwater systems were adapted for "Ten State Standards."
The General Design Criteria for operation and maintenance of public water systems were adapted from "Ten States Standards," also referred to as "Recommended Standards for Water Works," created by the Great Lakes Upper Mississippi River Board of State and Provincial Public Health and Environmental Managers.
"Ten State Standards," 2003 edition, is incorporated by reference into Kentucky regulations for public water supply 401 KAR Chapter 8 and is used by the Kentucky Division of Water for review of drinking water projects. The publication is available from Health Education Services in Albany, N.Y., at http://www.hes.org/ or 518-439-7286.
For additional resources, contact the Safe Drinking Water Hotline at 800-426-4791. For guidance manuals and laboratory quality assurance program for LT2, see EPA's Web page on "Microbials and Disinfection Byproducts."
Guidance for determining source water as Ground Water Under Direct Influence (GWUDI).
The Surface Water Treatment Rule (SWTR) of 1989 requires all raw water sources be evaluated to determine if they are surface water or groundwater. The definition of surface water includes groundwater under the direct influence (GWUDI) of surface water.
The technical document GWUDI determinations provides guidance on identifying raw water sources.
The purpose of the rule is to remove waterborne, disease-causing microbes from drinking water, specifically the viruses Legionella (a bacterium) and Giardia lamblia (a microscopic parasite). Refer to the national primary drinking water regulations, 40 CFR 141.70-.75.
The rule sets at zero the maximum contaminant limit goals for Legionella, Giardia and other viruses since any amount of exposure to these contaminants represents some health risk. The rule also sets treatment technique requirements to control these contaminants.
Under these requirements, all systems using surface water must filter and disinfect their water to provide a minimum of 99.9 percent combined removal and inactivation of Giardia and 99.99 percent of viruses. The adequacy of the filtration process is established by measuring turbidity (a measure of the clarity of water) in the treated water and determining if it meets EPA's performance standard.
To assure adequate microbial protection in the distribution system, the rule also requires systems to provide continuous disinfection of the drinking water entering the distribution system and to maintain a detectable disinfectant level within the distribution system.