Idaho Admin. Code r. 58.01.08.501

Current through September 2, 2024

Section 58.01.08.501 - GENERAL DESIGN REQUIREMENTS FOR PUBLIC DRINKING WATER SYSTEMS

Unless otherwise specified by the Department, the design of new PWSs, or modifications to existing PWSs must conform to the facility and design standards set forth in 40 CFR 141.5, and Sections 500 through 552. The following general design requirements apply as applicable for the type of PWS and the treatment or other processes employed.

01.Materials Used in Construction. Products that are used to construct PWSs and have water contact surfaces must conform to applicable AWWA standards and be certified by an accredited ANSI certification body to meet applicable ANSI/NSF standards, where products meeting such AWWA and ANSI/NSF standards exist, and must conform to 40 CFR 143 Subpart B. In the absence of such products, products meeting applicable product standards and acceptable to the Department may be selected. Corrosion control must be taken into account during all aspects of PWS design.

02.Additives Used in Operation. No chemical or other substance will be added to drinking water, nor will any process be utilized to treat drinking water, unless approved by the Department. All chemicals must conform to applicable AWWA standards and be certified by an accredited ANSI certification body to meet ANSI/NSF Standard 60, referenced in Subsection 002.02.

03.Design Basis. The PWS, including the water source and treatment facilities, must be designed to provide either peak hour demand of the PWS or maximum day demand plus equalization storage at the design year.

04.Design of Treatment Facilities. Design of treatment facilities must address:

a. Functional aspects of facility layout and provisions for future facility expansion;

b. Provision for expansion of waste treatment and disposal facilities (see Section 540);

c. Roads constructed to provide year-round access by vehicles and equipment needed for repair and maintenance;

d. Site grading and drainage; and

e. Chemical feed or injection systems must be designed to ensure complete mixing through rapid mix devices or other measures unless otherwise approved by the Department.

f. Unless otherwise approved by the Department or as specified in other sections of these rules, to ensure that minimum quality, quantity, and pressure requirements are continuously met during maintenance, breakdowns, structural failures, emergencies, or other periods when components must be out of service, water system treatment, filtration, and disinfection components for all new or substantially modified community or non-transient, non-community PWSs must be designed with redundancy or other acceptable methods, such that plant design capacity can be maintained with any component out of service. Raw water intake structures are excluded from the general redundancy requirement but must be designed to ensure that plant design capacity will be maintained.

05.Design of Buildings. The design of buildings that are a part PWSs must provide for:

a. Adequate ventilation, lighting, heating, and air conditioning;

b. Adequate drainage;

c. Dehumidification equipment, if necessary;

d. Accessibility of equipment for operation, servicing, and removal;

e. Flexibility and convenience of operation and safety of operators; and

f. Separate room(s) for chemical storage and feed equipment that may be required based on type of chemicals and associated hazards.

06.Electrical. Main switch gear electrical controls must be located above grade, in areas not subject to flooding. All electrical work must conform to the requirements of the National Electrical Code or to relevant state/local codes. The National Electrical Code is available from the National Fire Protection Association, 1 Batterymarch Park, Quincy, Massachusetts 02169-7471, (617)770-3000, http://www.nfpa.org.

07.Reliability and Emergency Operation. New community PWSs are required to have sufficient dedicated on-site standby power, with automatic switch-over capability, or standby storage so that water may be treated and supplied to pressurize the entire distribution system during power outages. During a power outage, the PWS must be able to meet the operating pressure requirements of Subsection 552.01.b. for a minimum of eight (8) hours at average day demand plus fire flow where provided. A minimum of eight (8) hours of fuel storage must be located on site unless an equivalent plan is authorized by the Department. Standby power provided in a PWS may be coordinated with the standby power that is provided in the wastewater collection and treatment system.

a. The Department may require the installation of standby power or storage facilities in existing PWSs if the frequency and duration of power outages a PWS experiences constitute a health hazard.

b. Existing community PWSs that are substantially modified must meet the requirements of Subsection 501.07. in those portions of the PWS affected by the modifications.

c. New sources and booster pumps intended to increase PWS capacity must be provided with standby power or equivalent unless, during a power outage, the PWS or distribution system pressure zone can already meet the minimum operating capacity and pressure requirements in Subsection 501.07 for a minimum of eight (8) hours at average day demand plus fire flow where provided for each pressure zone.

d. For both new and existing PWSs, the Department may reduce the requirements of Subsection 501.07 if the PWS can demonstrate the capacity to adequately protect public health during a power outage. Any decision by the Department will be based on, but not limited to, the following considerations:

i. An adequate emergency response and operation plan and the capacity to implement that plan.

ii. The adequacy of the PWS's cross connection control program and the capacity to protect public health in the event of a system wide depressurization.

iii. Demonstration of historical and projected reliability of the electrical power supplied to the PWS.

iv. A strategy for providing information to the public during power outages, including instructions to stop irrigation, boil water, etc., until notified otherwise.

v. The level of reliability acceptable to consumers. This can be accomplished with either a vote of the majority of consumers for privately owned and operated PWSs or a decision by the governing body for publicly governed PWSs.

vi. Other considerations that may be pertinent, including connections to other PWSs, agreements to provide water in emergency situations, and the availability of dedicated portable auxiliary power.

08.On-Site Analysis and Testing Capabilities. Each PWS must have equipment and facilities for routine testing necessary to ensure proper operation. Equipment selection must be based on the characteristics of the raw water source and the complexity of the treatment process involved.

09.Sample Taps. Sample taps must be provided so that water samples can be obtained from each water source and from appropriate locations in each unit operation of treatment, and from the finished water. Taps must be consistent with sampling needs and shall not be of the petcock type. Taps owned by the PWS and used for obtaining samples for bacteriological analysis must be of the smooth-nosed type without interior or exterior threads, will not be of the mixing type, and will not have a screen, aerator, or other such appurtenance.

10.Facility Potable Water Supply. The facility water supply service line and the plant finished water sample tap must be supplied from a source of finished water at a point where all chemicals have been thoroughly mixed, and the required disinfectant contact time, if applicable, has been achieved. There may be no cross connections between the facility water supply service line and any piping, troughs, tanks, or other treatment units containing wastewater, treatment chemicals, raw or partially treated water.

11.Meters. All water supplies must have an acceptable means of measuring the flow from each source, the wash water, the recycled water, any blended water of different quality, and the finished water.

12.Operation and Maintenance Manual. A new or updated operation and maintenance manual that addresses all PWS facilities must be submitted to the Department for review and approval prior to start-up of the new or materially modified PWS unless the same system components are already covered in an existing operation and maintenance manual. For existing PWSs with continual operational problems as determined by the Department, the Department may require that an operation and maintenance manual be submitted to the Department for review and approval. The operator will ensure that the PWS is operated in accordance with the approved operation and maintenance manual.

13.Start-Up Training. Provisions must be made for operator instruction at the start-up of a new plant or pumping station.

14.Safety. Consideration must be given to the protection of maintenance personnel and visitors from typical and foreseeable hazards in accordance with the engineering standards of care. The design must comply with all applicable safety codes and regulations that may include the Uniform Building Code, International Fire Code, National Fire Protection Association Standards, and state and federal OSHA standards. Items to be considered include, but are not limited to, noise arresters, noise protection, confined space entry, protective equipment and clothing, gas masks, safety showers and eye washes, handrails and guards, warning signs, smoke detectors, toxic gas detectors and fire extinguishers.

15.Security. Appropriate design measures to help ensure the security of PWS facilities must be incorporated. Such measures, at a minimum, will include means to lock all exterior doorways, windows, gates and other entrances to source, treatment, pumping stations, and water storage facilities.

16.Other Regulations. Consideration must be given to the design requirements of other federal, state, and local regulatory agencies for items such as safety requirements, special designs for the handicapped, plumbing and electrical codes, and construction in the flood plain.

17.Groundwater Source Redundancy. New community PWSs served by groundwater must have a minimum of two (2) sources if they are intended to serve more than twenty-five (25) connections or equivalent dwelling units (EDUs). Under normal operating conditions, with any source out of service, the remaining source(s) must be capable of providing either the peak hour demand of the PWS or a minimum of the maximum day demand plus equalization storage. See Subsection 501.18 for general design and redundancy requirements concerning fire flow capacity.

18.Redundant Fire Flow Capacity.

a. PWSs that provide fire flow must be designed to provide maximum day demand plus fire flow. Fire flow requirements and system adequacy will be determined by the local fire authority or by a hydraulic analysis by a licensed professional engineer to establish required fire flows in accordance with the International Fire Code as adopted by the State Fire Marshal. Pumping systems supporting fire flow capacity must be designed so that maximum day demand plus fire flow may be provided with any pump out of service.

b. The requirement for redundant pumping capacity specified in Subsection 501.18.a. may be reduced to the extent that fire suppression storage is provided in sufficient quantity to meet some or all of fire flow demands. Where fire suppression storage is not provided, the requirement for fire flow pumping redundancy may be reduced or eliminated if the following conditions are met:

i. The local fire authority justifies that the fire flow capacity of the PWS is acceptable and is compatible with the water demand of existing and planned fire-fighting equipment and fire-fighting practices in the area served by the PWS.

ii. In a manner appropriate to the PWS type and situation, notification is provided to customers that describes the design of the PWS's fire-fighting capability and explains how it differs from the requirements of Subsection 501.18.a.

19.Pilot Studies. Unless otherwise approved by the Department, pilot studies are required for treatment processes other than chlorine disinfection or point of use installations. Pilot studies may be performed in the field using the proposed source water or in conjunction with bench scale testing in the lab using the proposed source water. The PWS must obtain the Department's approval of a pilot study plan before the pilot study is implemented. A pilot study will be conducted for a period that is determined by the design engineer and approved by the Department. A final pilot study report with results must be submitted to the Department for review and approval. Upon completion of the pilot study, final approval of equipment and treatment processes is subject to the applicable requirements of Sections 500 through 552.

a. A pilot study plan must include the following and any other items required by the Department:

i. General information about the project including the existing system, the reason for conducting the pilot study, and anticipated results of a successful pilot study.

ii. A brief description of alternative processes that may be used if the proposed process is shown to be ineffective from the study.

iii. Discussion of how the pilot study will be conducted, the time frame of the study, source water quality, how source water may be altered to mimic various source water quality conditions, and the water quality parameters that are monitored and evaluated to determine if the treatment process was effective.

b. The pilot study report must include the following and any other items required by the Department:

i. Introduction and Background.

ii. A discussion of the overall pilot study progress, including any issues or problems and a general discussion of results of the study and what the results indicate. This discussion will determine parameters necessary for full scale implementation.

iii. Conclusions and recommendation to proceed with the treatment process if the results of the study proved successful.

c. Additional specific pilot study requirements in Sections 500 through 552 must be included in pilot study plans and reports.

d. Pilot study plans and pilot study reports submitted to the Department must bear the imprint of an Idaho licensed professional engineer's seal that is both signed and dated by the engineer.

Idaho Admin. Code r. 58.01.08.501

Effective July 1, 2024