Idaho Admin. Code r. 58.01.08.552

Current through September 2, 2024

Section 58.01.08.552 - OPERATING CRITERIA FOR PUBLIC WATER SYSTEMS

01.Quantity and Pressure Requirements. Design requirements regarding pressure analysis are found in Section 542.13.

a. The minimum capacity of a PWS must be at least eight hundred (800) gallons per day per residence.

i. The minimum capacity of eight hundred (800) gallons per day is the design maximum day demand rate exclusive of irrigation and fire flow requirements.

ii. The minimum capacity of eight hundred (800) gallons per day is only acceptable if the PWS has equalization storage of finished water in sufficient quantity to compensate for the difference between a PWS's maximum pumping capacity and peak hour demand.

iii. The design capacity of a PWS for material modifications may be less than eight hundred (800) gallons per day if the PWS owner provides information that demonstrates to the Department's satisfaction the maximum day demand for the PWS, exclusive of irrigation and fire flows, is less than eight hundred (800) gallons per day per residence.

b. All PWS owners must meet the following pressure requirements:

i. Be capable of providing sufficient water during maximum day demand conditions, including fire flow where provided, to maintain a minimum pressure of twenty (20) psi throughout the distribution system, at ground level, as measured at the service connection or along the property line adjacent to the consumer's premises.

ii. If an initial investigation by the water supplier fails to discover the causes of inadequate or excessive pressure, the Department may require the water supplier to conduct a local pressure monitoring study to diagnose and correct pressure problems. Compliance with these requirements by PWSs that do not have a meter vault or other point of access at the service connection or along the property line adjacent to the consumer's premises where pressure in the distribution system can be reliably measured must be determined by measurements within the consumer's premises, or at another representative location acceptable to the Department.

iii. Copies of pressure monitoring study reports required under Subsection 552.01.b.iii. detailing study results and any resulting corrective actions planned or performed by the PWS owner must be submitted to the Department in accordance with these rules.

iv. The following PWSs or service areas of PWSs must maintain a minimum pressure of forty (40) psi throughout the distribution system, during peak hour demand conditions, excluding fire flow, measured at the service connection or along the property line adjacent to the consumer's premises.

(1) Any PWS constructed or substantially modified after July 1, 1985.

(2) Any new service areas.

(3) Any PWS that is undergoing material modification where it is feasible to meet the pressure requirements as part of the material modification.

v. Any newly constructed PWSs, or portions of existing systems that are materially modified after July 1, 2024, must keep static pressure within the distribution system below eighty (80) psi. Pressures above eighty (80) psi must be controlled by pressure reducing valve stations installed in the distribution main. In areas where failure of installed pressure reducing valve stations result in extremely high pressure, pressure relief valves may be required. The Department may approve the use of pressure reducing devices at individual service connections on a case-by-case basis, if it can be demonstrated that higher pressures in portions of the distribution system are required for efficient PWS operation. If PWS modification will cause pressure to routinely exceed eighty (80) psi, or if a check valve or an individual pressure reducing device is added to the service line, the PWS owner must notify affected customers. Notification may include reasons for the elevated pressure, problems or damage that elevated pressure can inflict on appliances or plumbing systems, and suggested procedures or mitigation efforts affected property owners may initiate to minimize problems or damage.

vi. The Department may allow the installation of booster pump systems at individual service connections on a case-by-case basis. However, such an installation may only occur with the full knowledge and agreement of the PWS owner, including assurance by the PWS that the individual booster pump will cause no adverse effects on PWS operation.

vii. For elevated storage tanks, pressure calculations during peak hour demand are based on the lowest water level after both operational storage and equalization storage have been exhausted. Pressure calculations during fire flow demands are based on the lowest water level after operational storage, equalization storage, and fire suppression storage have been exhausted.

viii. For hydropneumatic tanks, pressure calculations are based on the lowest pressure of the pressure cycle and this requirement must be noted in the operation and maintenance manual.

c. Any PWS designed to provide fire flows must ensure that such flows are compatible with the water demand of existing and planned fire-fighting equipment and fire fighting practices in the area served by the PWS.

d. Irrigation Flows.

i. Any PWS constructed after November 1, 1977, must be capable of providing water for uncontrolled, simultaneous foreseeable irrigation demand, which includes all acreage that the PWS is designed to irrigate.

(1) The Department must concur with assumptions regarding the acreage to be irrigated. In general, an assumption that no outside watering will occur is considered unsound and is unlikely to be approved.

(2) An assumption of minimal outside watering, as in recreational subdivisions, may be acceptable if design flows are adequate for maintenance of "green zones" for protection against wildland fire.

ii. The Department may modify the requirement of Subsection 552.01.d.i. if:

(1) A separate irrigation system is provided; or

(2) The supplier of water can regulate the rate of irrigation through its police powers, and the PWS is designed to accommodate a regulated rate of irrigation flow. The Department may require the PWS to submit a legal opinion addressing the enforceability of such police powers.

iii. If a separate non-potable irrigation system is provided for the consumers, all mains, hydrants and appurtenances must be easily identified as non-potable. The Department must concur with a plan to ensure that each new potable water service is not cross-connected with the irrigation system.

02.Groundwater.

a. PWSs supplied by groundwater, must treat water within the PWS by disinfection if the groundwater source is not protected from contamination.

b. The Department may require disinfection for any existing PWS supplied by groundwater if the PWS has repeated E.coli MCL exceedances, and if the PWS does not appear adequately protected from contamination. Adequate protection will be determined based upon at least the following factors:

i. Location of possible sources of contamination;

ii. Size of the well lot;

iii. Depth of the source of water;

iv. Bacteriological quality of the aquifer;

v. Geological characteristics of the area; and

vi. Adequacy of development of the source.

03.Operating Criteria. The operating criteria for PWSs that provide filtration are as follows:

a. A project specific operation and maintenance manual must be provided as required in Subsection 501.12. See definition of Operation and Maintenance Manual in Section 003 for the typical contents of an operation and maintenance manual and the included operations plan. For the operations plan in the operation and maintenance manual, additional guidance for several types of filtration systems can be found in the Department's SWTR Compliance Guidance referenced in Subsection 002.02.

b. The PWS must conduct monitoring specified by the Department before serving water to the public in order to protect the health of consumers served by the PWS.

c. New treatment facilities must be operated in accordance with Subsection 552.03.a., and the PWS must conduct monitoring specified by the Department for a trial period specified by the Department before serving water to the public in order to protect the health of consumers served by the PWS.

04.Disinfection. PWSs that regularly disinfect their water using chlorine are subject to the provisions of Section 320. PWSs using surface water or groundwater under the direct influence of surface water, are subject to the disinfection requirements of Sections 300 and 518. PWSs using chlorine, ozone, chlorine dioxide, or other disinfecting agents for the purposes of disinfection must meet the facility and design standards of Sections 530 and 531. PWSs using ultraviolet light for the purposes of disinfection must meet the facility and design standards of Section 529.

a. PWSs using only ground water that add a disinfectant for the purpose of disinfection, as defined in Section 003, are subject to the following requirements:

i. The PWS must demonstrate that it is routinely achieving four (4) logs (ninety-nine point ninety-nine percent) (99.99%) inactivation/removal of viruses. The required effective contact time must be approved by the Department. This condition must be attainable even when the design capacity coincides with anticipated maximum disinfectant demands.

ii. A detectable disinfectant residual must be maintained throughout the distribution system. PWSs disinfecting through ultraviolet light will need to maintain a supplemental disinfectant capable of maintaining a detectable disinfectant residual.

iii. Analysis for disinfectant residual must be conducted at a location at or prior to the first service connection at least daily and records of these analyses are to be kept by the supplier of water for at least one (1) year. A report of all daily chlorine residual measurements for each calendar month must be submitted to the Department no later than the tenth day of the following month. The frequency of measuring disinfectant residuals must be sufficient to detect variations in demand or changes in water flow.

iv. The Department may, in its discretion, require a treatment rate higher than that specified in Subsection 552.04.a.i.

b. PWSs using only groundwater that add disinfectant for the purpose of maintaining a disinfectant residual in the distribution system, when the source(s) is not at risk of microbial contamination, are subject to analysis for disinfectant residual made at a frequency that is sufficient to detect variations in demand or changes in water flow.

c. PWSs using only groundwater that add chlorine for other purposes, such as oxidation of metals or taste and odor control, when the source(s) is known to be free of microbial contamination, must ensure that chlorine residual entering the distribution system after treatment is less than four (4.0) mg/L. The requirements in Subsection 552.04.b.ii. also apply if the PWS maintains a chlorine residual in the distribution system.

05.Fluoridation.

a. Commercial sodium fluoride, sodium silico fluoride and hydrofluosilicic acid which conform to the applicable American Water Works Association (AWWA) Standards, incorporated by reference into these rules at Subsection 002.01, are acceptable. Use of other chemicals must be specifically approved by the Department.

b. Fluoride compounds are to be stored in covered or unopened shipping containers.

c. Provisions must be made to minimize the quantity of fluoride dust. Empty bags, drums, or barrels are to be disposed of in a manner that will minimize exposure to fluoride dusts.

d. Daily records of flow and amounts of fluoride added must be kept. An analysis for fluoride in finished water must be made at least weekly. Records of these analyses are to be kept by the supplier of water for five (5) years.

06.Cross Connection Control Program - Community Water Systems. The water purveyor is responsible through its cross connection control program to take reasonable and prudent measures to protect the PWS against contamination and pollution from cross connections through premises isolation, internal or in-plant isolation, fixture protection, or some combination of premises isolation, internal isolation, and fixture protection. Pursuant to Section 543, all suppliers of water for community PWSs must implement a cross connection control program to prevent the entrance to the PWS of materials known to be toxic or hazardous. The water purveyor is responsible to enforce the PWS's cross connection control program. The program will at a minimum include:

a. An inspection program to locate cross connections and determine required suitable protection. For new connections, PWS owners must verify suitable protection was installed prior to providing water service.

b. Required installation and operation of adequate backflow prevention assemblies. Appropriate and adequate backflow prevention assembly types for various facilities, fixtures, equipment, and uses of water must be selected from the Uniform Plumbing Code, the AWWA Recommended Practice for Backflow Prevention and Cross Connection Control (M14), the USC Foundation Manual of Cross Connection Control, or other sources deemed acceptable by the Department. The assemblies must meet the requirements of Section 543 and comply with local ordinances.

c. Annual inspections and testing of all installed backflow prevention assemblies by a tester licensed by a licensing authority recognized by the Department. Testing must be done in accordance with the test procedures published by the University of Southern California Foundation for Cross-Connection Control and Hydraulic Research. See the USC Foundation Manual of Cross-Connection Control referenced in Subsection 002.02.

d. Discontinuance of service to any structure, facility, or premises where suitable backflow protection has not been provided for a cross connection.

e. Assemblies that cannot pass annual tests or those found to be defective are to be repaired, replaced, or isolated within ten (10) business days. If the failed assembly cannot be repaired, replaced, or isolated within ten (10) business days, water service to the failed assembly must be discontinued.

07.Cross Connection Control - Non-Community Water Systems. All suppliers of water for non-community water systems must ensure that cross connections do not exist or are isolated from the potable water system by an approved backflow prevention assembly. Backflow prevention assemblies must be inspected and tested annually for functionality by an Idaho licensed tester, as specified in Subsections 552.06.c. and 552.06.e.

08.Start-up Procedures For Seasonal Systems Subject To Subsections 100.01.a., c., and d.

a. All seasonal PWS owners must demonstrate completion of a Department approved start-up procedure, including start-up sampling, prior to serving water to the public. The PWS owner must submit information on a Department provided or approved form that includes a statement certifying that the PWS owner or operator followed proper start-up procedures. The form must be submitted to the Department within 30 (thirty) days following the PWS's start-up date. Start-up sampling must include total coliform samples submitted to a certified laboratory demonstrating the absence of total coliform within thirty (30) days prior to serving water to the public.

b. The Department may exempt any seasonal PWS from Subsection 552.08.a. if the entire distribution system remains pressurized during the entire period that the PWS is not operating, except that the PWSs that monitor less frequently than monthly must still monitor during the vulnerable period designated by the Department. The Department may exempt a seasonal PWS from Subsection 552.08.a. if the owner or operator of the PWS meets all of the following conditions:

i. Requests an exemption in writing to the Department for approval;

ii. Demonstrates a clean compliance history as defined in Section 003 for a minimum of five (5) years;

iii. Has no uncorrected significant deficiencies from the most recent sanitary survey; and

iv. Total coliform samples submitted to a certified laboratory within 30 (thirty) days prior to serving water to the public demonstrate the absence of total coliform.

Idaho Admin. Code r. 58.01.08.552

Effective July 1, 2024