The Fairfax County Water Authority (“Fairfax Water”) appreciates the opportunity to comment on the proposed amendments to the above-referenced Waterworks Regulations (the “Regulations”).  

Fairfax Water is the largest water utility in Virginia, serving one out of every four citizens who obtain their water from public utilities. Nearly 2 million residents of Northern Virginia, including large portions of Fairfax, Loudoun, and Prince William Counties, the Towns of Herndon and Vienna, Dulles Airport, Ft. Belvoir and the Cities of Falls Church, Fairfax, and Alexandria, depend on Fairfax Water for their drinking water. Fairfax Water relies on the Potomac River and the Occoquan Reservoir as its water supply sources. Fairfax Water also purchases water from the Washington Aqueduct Division of the U.S. Army Corps of Engineers, a water supply sourced from the Potomac River.  

Overall, Fairfax Water supports the proposed amendments to the regulations and appreciates the efforts of the Waterworks Advisory Committee to review and discuss substantive changes to the regulation. Fairfax Water strongly urges VDH to emphasize practical implementation of these Regulations so that VDH Central and Field Offices focus their resources on meaningful public health protection. Specific sections with additional comments are noted as follows.  

12 VAC5-590-830: Surface Water Sources: Quantity, Quality, Development Structures 

We appreciate VDH’s retainage of this important section of the regulations.  The purpose of the Waterworks Regulation is to ensure that the citizens of Virginia have safe, reliable drinking water and as such, VDH plays an important role with individual waterworks owners in achieving this mission. The Code of Virginia (62-1-44.15-22) relating to surface waters supplies contains an important distinction in identifying domestic (and existing beneficial uses) as the highest priority water use. Water supply requirements identified in Section 830 of the Waterworks Regulations provide a vital link between individual waterworks VDH operating permits and their respective public drinking water withdrawals, including those waterworks exempt from withdrawal permit under 62-1-44:15-22 of the Code of Virginia. 

12 VAC 5-590-730: Alternate Power Sources 

We applaud the proposed change of this section title from “Standby Power Capability” to “Alternate Power Sources”, intended to provide waterworks with more options to be considered for providing power during an electrical power outage. As waterworks consider alternative power sources to maintain a minimum level of service during an electrical power outage, they will benefit from having a larger suite of options available to voluntarily and cost-effectively improve their electrical reliability. 

12 VAC 5-590-640 General Design Considerations 

The proposed Waterworks Regulation repeals fixed consumption methods (previously provided in Section 690-Capacity of Waterworks) in favor of use of a hydraulic model to demonstrate that maximum day demands are met. The Agency Background Document (dated 3/12/2021) identifies that the current fixed consumption formulas (based on Section 690) result in “inaccurate estimates” and storage criteria that results in “excess storage requirements” for large waterworks (see p.106, Agency Background Document). As fixed demand and storage requirements are removed from this regulation, VDH must consider individual waterworks system specific factors, availability of alternate power supply sources, and alternative operating modes in evaluating acceptable storage and demand design basis. Many waterworks often have multiple sources of supply and multiple operating modes which enhances their reliability as compared with traditional single source systems. 

12 VAC 5-590-570 Operational Reporting Requirements 

The ozone reporting requirements for disinfection credits are unclear with the guidance provided.  To date, VDH Office of Drinking Water Working Memo 899 (“WM 899”, Revision 11/18/2010) has provided the clearest description of monthly operation reporting requirements and uses more precise language to help explain the requirements to demonstrate compliance.  Table 570.14 of the Regulations references “Cinitial from the first sample point” where WM 899 requires the “Ozone Residual, initial (mg/L) from the last dissolution chamber of each contactor” be reported.  The WM 899 value has direct relation to direct ozone Contact Time (CT) credit achieved where the value required in the Regulations may or may not.  If the intent is to codify WM 899 in this update, Fairfax Water recommends using the more precise language and reporting requirements outlined in the Working Memo.  If the intent is to maintain a separate guidance document, then FW recommends using more general language in the Regulations.  

We recommend that VDH align the authorized calculation methods in Table 570.14 of the Regulations to those described in the EPA Long-Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) Toolbox: T10 method, CSTR method, Extended T10 method, and Extended CSTR method.  “Effluent Method” is the same as T10 method but the name “Effluent Method” is never described in the EPA document.  The Log Integration method in the Regulations also does not exist in the Toolbox and seems to be a modified T10 method using the geometric mean.   

Thank you in advance for the opportunity to participate in this important process.