Water System Design Manual, December 2009
Document source : www.doh.wa.gov
Water System Design Manual
December 2009
Page 295
operating and water quality conditions, and actual installations must be operated within specified
parameters consistent with the validation. Therefore, DOH will require that each reactor design
undergo dosimeter-based validation testing prior to being approved for use in Washington State.
UV reactors must be validated to establish the range of operating conditions that qualify for
pathogen inactivation credit. Detailed, defined testing protocols have been developed in
Germany (DVGW 2006
)
and Austria (ÖNORM
2001; ÖNORM
2003). Reactors certified at an
approved DVGW (Deutsche Vereinigung des Gas und Wasserfaches) testing facility using the
DVGW W294 protocol or ÖNORM (Österreichisches Normungsinstitut) facility using the
ÖNORM M5873-1 or ÖNORM M5873-2 protocol will be considered as providing a reduction
equivalent dose of 40 mJ/cm
2
within the validated conditions. For other validation efforts,
Chapter 5 of the final UVDGM (USEPA 2006) will be used to review proposed validation
protocols. A full-scale reactor must be used for all validation testing.
There are two different UV dose-monitoring strategies commonly used to control UV reactors
and confirm that the reactor is providing the required dose within the validated range of
operations. The sensor setpoint approach is one UV dose monitoring strategy. The other strategy
is called the calculated dose approach. The DVGW W 294 and ÖNORM M5873 protocols use
the sensor setpoint approach. Guidelines for the calculated dose approach are outlined in the
UVDGM (USEPA 2006). The dose-monitoring strategy affects how a reactor validation is
conducted as well as how the reactor is monitored after it is installed.
It will be the responsibility of the UV equipment manufacturer to submit complete validation
information to DOH for review and approval. This responsibility includes submitting the details
of the testing protocol to DOH prior to the start of the testing. This validation will require
verification of the conditions under which at least the minimum validated dose is provided. A
third party acceptable to DOH must conduct the validation, not the manufacturer or water
system.
Public Health Criteria
Disinfection requirements for ground and surface water systems are addressed in chapter 246-
290 WAC. These are discussed in turn below.
Groundwater Sources Requiring Disinfection
WAC 246-290-250 requires disinfection of groundwater supplies unless acceptable source water
quality (for example, historical absence of coliform organisms) and an acceptable sanitary
control area are provided. Sources that are determined to be in hydraulic connection with
adjacent surface water must also provide disinfection (WAC 246-290-640). The specified level
of treatment is identified in WAC 246-290-451(3), and requires a multiplicative combination of
chlorine residual (C) and contact time (T) that results in a product (termed CT) of at least 6
mg/L-min. This is identified in the Surface Water Treatment Rule Guidance Manual (USEPA
1990) with use of free chlorine as the required level to provide 4-log inactivation of viruses in
water at 10
o
C, pH 6-9. The values in EPA's guidance manual are based on hepatitis A virus
Summary :
Water System Design Manual December 2009 Page 295 operating and water quality conditions, and actual installations must be operated within specified parameters consistent with the validation. Reactors certified at an approved DVGW (Deutsche Vereinigung des Gas und Wasserfaches) testing facility using the DVGW W294 protocol or ÖNORM (Österreichisches Normungsinstitut) facility using the ÖNORM M5873-1 or ÖNORM M5873-2 protocol will be considered as providing a reduction equivalent dose of 40 mJ/cm 2 within the validated conditions.
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alidation,water,dose,testing,norm,reactor,wac,alidated,dgw,approach,doh,conditions,disinfection