New York City Department of Environmental Protection (DEP) is actively planning for the implementation of an ultraviolet light (UV) disinfection facility as an additional treatment barrier for the City's Catskill and Delaware supplies. The Catskill and Delaware supplies are pristine in nature, which has allowed the DEP to continue a Filtration Avoidance Determination with the United States Environmental Protection Agency (EPA). Of the nearly 2 billion gallons of drinking water consumed daily in New York City, nearly 90 percent is supplied from the Catskill and Delaware system. DEP has committed to the design and construction of a UV disinfection facility for the Catskill and Delaware supplies under the agreement with EPA. As part of this commitment, DEP has developed a Conceptual Design of the UV disinfection facility that has incorporated UV reactors with nominal capacities of 40-mgd. As part of the Conceptual Design, DEP began a modeling program to demonstrate that integrated models of UV light intensity distribution (LID) and computational fluid dynamics (CFD) can effectively predict UV reactor performance. Initially, a small-scale reactor (<20 mgd) was modeled to determine if predicted modeling results agree with biodosimetry data obtained during physical testing of the reactors. During Preliminary Design, additional small-scale reactors will be modeled to prove that reactors of different sizes and configurations can be effectively modeled. The models can then be used to predict the performance of larger reactors that have not been validated with biodosimetry. The DEP's approach to using modeling as a means for validation is to initially model UV reactors that have been physically validated using biodosimetry. After demonstrating that the computer models can predict (within a defined confidence interval) results measured during biodosimetry testing, the modeling approach can be used for scale up and design of a facility with larger reactors. The results of the initial computer modeling, as presented in this paper show that the approach is feasible. Includes 10 References, tables, figures.
