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The Design Guidelines for First nations Water Works (Design Guidelines) were developed to serve as a general guide to engineers in the preparation of plans and specifications for public water supply systems on First Nations Lands.
The intent of this Document is to propose limiting values for parameters and components from which an evaluation may be made by the reviewing authority of the engineer's plans and specifications. The fundamental intent of this Document is therefore to establish, as far as is practical, a uniformity of design and practice for First Nations water systems.
In recent years, some chemical contaminants have had their maximum acceptable concentration (MAC) levels reduced while concern for microbiological contaminants in public water supplies has heightened. Recent events in Canada have emphasized the need for both filtration and continuous disinfection of any surface water or groundwater under the direct influence of surface water (GUDI).
As far as is practicable, this document includes recently developed processes and equipment currently available to the water industry.
The policy of these Design Guidelines is to encourage, rather than obstruct, the development of new processes and equipment. Thus, recent developments may be acceptable if they meet at least one of the following conditions:
In addition to the above conditions, in order to be considered acceptable, recent developments must be proven to be effective in treating the same type of water as will actually be treated at the project site.
This document is intended for use by individuals who, are qualified to exercise the professional judgment necessary to select and design water supply facilities. The individual must be able to substantiate and define the design criteria based on engineering and scientific principles. Users should be cognizant of all applicable federal and provincial regulations, standards, protocols, and guidelines.
The terms "shall" and "must" are used where practice is sufficiently standardized to permit specific delineation of requirements or where safeguarding of the public health justifies such definite action. Other terms, such as "should", "recommended", and "preferred", indicate desirable procedures or methods, with deviations subject to individual considerations.
Where reference is made to the "reviewing authority" this refers to the person or body that will provide guidance or council on specific standards or as regulated by the appropriate government agencies.
This Document, adopts the same format, chapter structure and general contents as the "Recommended Standards for Water Works - 2003 Edition" prepared by The Great Lakes - Upper Mississippi River Board Water Committee (commonly known and referred to as the "Ten State Standards"). But, this document is updated and revised as necessary to suit the requirements and needs of First Nations communities.
These Design Guidelines address most of the additions and revisions of the 2003 Edition of the Ten State Standards and include these Policy Statements:
The source for many of the standards adopted herein is the publication "Recommended Standards for Water Works - 2003 Edition" which is a report of the Committee of the Great Lakes - Upper Mississippi River Board of State Engineers (of which the Province of Ontario is a member). As noted in the title of the source document, these Standards, better known as the 10- State Standards, were last updated in 2003.
These Design Guidelines are based on "INAC Design Guidelines for Water Works in BC Region, Fourth Edition" prepared by:
Lastly, for making available to the public, their wealth of technical information, a special thank you is extended to:
Pre-engineered water treatment plants are normally modular process units, which are predesigned for specific process applications and flow rates and purchased as a package. Multiple units may be installed in parallel to accommodate larger flows.
Pre-engineered water treatment plants have numerous applications but are especially applicable at small systems where conventional treatment may not be cost effective. As with any design the proposed treatment must fit the situation and assure a continuous supply of safe drinking water for water consumers. The reviewing authority may accept proposals for pre-engineered water treatment plants on a case-by-case basis where they have been demonstrated to be effective in treating the source water being used.
Factors to be considered include:
Although standards and advisories for organics are being developed, there have been numerous cases of organic contamination of public water supply sources. In all cases, public exposure to organic contamination must be minimized. There is insufficient experience to establish design standards which would apply to all situations. Controlling organic contamination is an area of design that requires pilot studies and early consultation with the reviewing authority. Where treatment is proposed, best available technology shall be provided to reduce organic contaminants to the lowest practical levels. Operations and monitoring must also be considered in selecting the best alternative. The following alternatives may be applicable:
Consideration should be given to:
Except for temporary, emergency treatment conditions, particular attention should be given to developing an engineering report which, in addition to the normal determinations, includes the following:
The collection of the type of data listed above is often complicated and lengthy. Permanent engineering solutions will take significant time to develop. The cost of organic analyses and the availability of acceptable laboratories may further complicate both pilot work and actual operation.
Alternative source development or purchase of water from nearby unaffected systems may be a more expedient solution for contaminated groundwater sources.
Internal and external corrosion of a public water supply distribution system is a recognized problem that cannot be completely eliminated but can be effectively controlled. Aside from the economic and aesthetic problems, the possible adverse health effects of corrosion products, such as lead and copper, is a major consideration. See Section 8.6.7 for external corrosion control.
Corrosion of metallic pipes is a chemical oxidation process, which requires that both water and an oxidizing agent be present at metal surfaces. The process is driven by the energy released when atoms from the metal surface are converted into hydrated metal cations. The three main factors which can accelerate corrosion are:
Control of corrosion is a function of the design, maintenance, and operation of a public water supply. These functions must be considered simultaneously in order for the corrosion control program to function properly. Corrosion problems must be solved on an individual basis depending on the specific water quality characteristics and materials used in the distribution system. Specific information can be obtained from publications of technical agencies and associations such as USEPA (Corrosion Manual for Internal Corrosion of Water Distribution Systems, 1984; Control of Lead and Copper in Drinking Water, 1993; Lead and Copper Regulations, 1994) and the American Water Works Association (Lead and Copper Strategies, 1990; Chemistry of Corrosion Inhibitors in Potable Waters, 1990; Internal Corrosion of Water Distribution Systems 2nd edition, 1996). Broad areas of consideration for a corrosion control program follow.
Note: Adjustment of pH for corrosion control must not interfere with other pH dependent processes (e.g., colour removal by alum coagulation) or aggravate other water quality parameters (e.g., THM formation). In addition, the use of ortho-or blended phosphates should not aggravate distribution microbial concerns or adversely impact wastewater facilities.
Trihalomethanes (THMs) are formed when free chlorine reacts with organic substances, most of which occur naturally. These organic substances (called "precursors"), are a complex and variable mixture of compounds. Formation of THMs is dependent on such factors as amount and type of chlorine used, temperature, concentration of precursors, pH, and contact time. Approaches for controlling THMs include:
Using various combinations of THM controls and removal techniques may be more effective than a single control or a treatment method.
All proposed modifications to existing treatment process must be approved by the reviewing authority. Pilot plant studies are desirable and may be necessary depending on the specific site conditions.
Reverse osmosis (RO) is a physical process in which a suitably pre-treated water is delivered at moderate pressures against a semi-permeable membrane. The membrane rejects most solute ions and molecules, while allowing water of very low mineral content to pass through. The process produces a concentrated waste stream in addition to the clear permeate product. Reverse osmosis systems have been successfully applied to saline groundwater, brackish water, and seawater, as well as for inorganic contaminants such as radionuclides, nitrates, arsenic, etc. and other contaminants such as pesticides, viruses, bacteria and protozoa. A lower pressure RO called nanofiltration (NF), also known as membrane softening, has been successfully utilized for hard, high colour and high organic content feed water. NF has a lower monovalent ion rejection, making it more attractive to water with low salinity, thereby reducing post treatment and conditioning as compared to RO.
The following items should be considered in evaluating the applicability for reverse osmosis and nanofiltration:
Recent advances in computer technology, equipment controls and Supervisory Control and Data Acquisition (SCADA) Systems have brought automated and off-site operation of surface water treatment plants into the realm of feasibility. Coincidentally, this comes at a time when renewed concern for microbiological contamination is driving optimization of surface water treatment plant facilities and operations and finished water treatment goals are being lowered to levels of <0.1 NTU turbidity and < 20 total particle counts per millimetre.
Any measures, including automation, which assist operators in improved plant operations and surveillance functions are encouraged.
Automation of surface water treatment facilities to allow unattended operation and off-site control presents a number of management and technological challenges which must be overcome before an approval can be considered. Each facet of the plant facilities and operations must be fully evaluated to determine what on-line monitoring is appropriate, what alarm capabilities must be incorporated into the design and what staffing is necessary. Consideration must be given to the consequences and operational response to treatment challenges, equipment failure and loss of communications or power.
An engineering report shall be developed as the first step in the process leading to design of the automation system. The engineering report to be submitted to review authorities must cover all aspects of the treatment plant and automation system including the following information/criteria:
Bag and cartridge technology has been used for some time in the food, pharmaceutical and industrial applications. This technology is increasingly being used by small public water supplies for treatment of drinking water. A number of states in the U.S.A. have accepted bag and cartridge technology as an alternate technology for compliance with the filtration requirements of the Surface Water Treatment Rule.
The particulate loading capacity of these filters is low, and once expended the bag or cartridge
filter must be discarded. This technology is designed to meet the low flow requirement needs of
small systems. The operational and maintenance cost of bag and cartridge replacement must be
considered when designing a system. These filters can effectively, remove particles from water
in the size range of Giardia cysts
(5-10 microns) and Cryptosporidium (2-5 microns).
At the present time, filtration evaluation is based on Giardia cyst removal. However, consideration should be given to the bag or cartridge filters ability to remove particles in the size range of Cryptosporidium since this is a current public health concern.
With this type of treatment there is no alteration of water chemistry. So, once the technology has demonstrated the required removal efficiency, no further pilot demonstration may be necessary. The demonstration of filtration is specific to a specific housing and a specific bag or cartridge filter. Any other combinations of different bags, cartridges, or housings will require additional demonstration of filter efficiency.
Treatment of surface water should include source water protection, filtration, and disinfection. The following items should be considered in evaluating the applicability of bag or cartridge filtration.
Low pressure membrane filtration technology has emerged as a viable option for addressing current and future drinking water regulations related to treatment of surface water sources and groundwater under the direct influence of surface water sources. Recent research and applied full scale facilities have demonstrated the efficient performance of both microfiltration (MF) and ultrafiltration (UF) as feasible treatment alternatives to traditional granular media processes. Both MF and UF have been shown to be effective in removing identified parameters of the Surface Water Treatment Rule, such as Giardia, Cryptosporidium, bacteria, turbidity and possibly viruses (for UF). The following provides a brief description and characteristics of each process as well as general selection and design considerations.
Characteristics: MF and UF membranes are most commonly made from organic polymers such as: cellulose acetate, polysulfones, polyamides, polypropylene, polycarbonates and polyvinylidene fluoride (PVDF). The physical configurations include hollow-fibre, spiral wound and tubular. MF membranes are capable of removing particles with sizes down to 0.1-0.2 microns. UF processes have a lower cutoff rating of .005-.01 microns.
Typical flux (rate of finished water permeate per unit membrane surface area) at 20°C for MF ranges between 2.05m/day to 4.1m/day whereas the typical UF flux range is 0.41 m/day to2.05 m/day. Required operating pressures ranges from 35 to 70 kPa for MF and 50 kPa to 350 kPa.
Since both processes have relatively small membrane pore sizes, membrane fouling, caused by organic and inorganic compounds as well as physical contaminants, can occur if the system is not properly selected or operated. Automated periodic back flushing and cleaning is employed on a timed basis or once a targeted transmembrane pressure differential has been reached. Some systems utilize air/water back flush. Typical cleaning agents utilized include acids, bases, complexing agents, surfactants, enzymes and certain oxidants, depending upon membrane material and foulants encountered. Chemicals used for cleaning and the method and procedure of cleaning process must be acceptable to the membrane manufacturer and approved by the reviewing authority.
Overall treatment requirements and disinfection credits must be discussed with and approved by the reviewing authority. Disinfection is required with membrane filtration for additional pathogen control and distribution system protection.
Ultra Violet (UV) Light treatment devices may be used to treat bacteriologically unsafe groundwater from drinking water wells. However, reviewing authorities expect water system owners to take all steps possible to obtain a naturally safe water source before considering treatment. A naturally safe water source provides the best long-term public health protection and there is no reliance on a treatment device to assure safe water. There must be a determination that the bacteriologically unsafe water is not due to the influence of surface water.
Recent research has demonstrated the effectiveness of UV as a primary disinfectant. While this policy statement does not specifically cover UV treatment for surface water or groundwater under the direct influence of surface water, it is not the intent of this policy to discourage such use. Portions of this policy are applicable to the treatment of effectively filtered surface water. The reviewing authority shall be contacted regarding use of UV treatment for these applications.
When a naturally safe groundwater source is not available, or the system owner wishes to provide UV treatment for other reasons, the following criteria shall be considered. Supplemental disinfection to provide a residual in the water distribution system will be required by the approval authority. When UV light treatment devices are used for non-health related purposes the UV device may provide doses less than indicated in the following criteria.
|UV 254 nanometers Absorption||20 percent at 1 cm|
|Dissolved Iron||0.3 mg/L|
|Dissolved Manganese||0.05 mg/L|
|Hardness||120 mg/L as CaCO3
(See note #1 below)
(if odour is present)
|pH||6.5 to 8.5|
|Suspended Solids||10 mg/L max.|
|Turbidity||1.0 NTU max.|
|Total Coliform||1,000/100 ML|
|E. Coli||See Note #2 below|
|Cryptosporidium||See Note #2 below|
|Giardia||See Note #2 below|
|Note #1: A higher hardness may be acceptable to the reviewing authority if experience with
similar water quality and reactors shows there are no treatment problems or
excessive maintenance required.
Note #2: These organisms may indicate that the source is either a surface water or groundwater under the direct influence of surface water and may require additional filtration pretreatment.
Raw water quality shall be evaluated and pretreatment equipment shall be designed to handle water quality changes. Variable turbidity caused by rainfall events is of special concern.
Security for public water system facilities is imperative. Review of public water systems security infrastructure and practices has shown an industry-wide vulnerability to intentional acts of vandalism, sabotage and terrorism. Protection from these types of threats must be integrated into all design considerations. Many public drinking water systems have implemented effective security and operational changes to help address this vulnerability, but additional efforts are needed.
Security measures are needed to help ensure that public water suppliers attain an effective level of security. Design considerations need to address physical infrastructure security, and facilitate security related operational practices and institutional controls. Because drinking water systems cannot be made immune to all possible attacks, the design needs to address issues of critical asset redundancy, monitoring, response and recovery. All public water supplies need to identify and address security needs in design and construction for new projects and for retrofits of existing drinking water systems.
The following concepts and items should be considered in the design and construction of new water system facilities and improvements to existing water systems:
Four treatment processes are generally considered acceptable for Nitrate/Nitrite removal. These are anion exchange, reverse osmosis, nanofiltration and electro dialysis. Although these treatment processes, when properly designed and operated will reduce the nitrate/nitrite concentration of the water to acceptable levels, primary consideration shall be given to reducing the nitrate/nitrite levels of the raw water through either obtaining water from an alternate water source or through watershed management. Reverse osmosis, nanofiltration or electro dialysis should be investigated when the water has high levels of sulfate or when the chloride content or dissolved solids concentration is of concern.
Most anion exchange resins used for nitrate removal are sulfate selective resins. Although nitrate selective resins are available, these resins typically have a lower total exchange capacity.
If a sulfate selective anion exchange resin is used beyond bed exhaustion, the resin will continue to remove sulfate from the water by exchanging the sulfate for previously removed nitrates resulting in treated water nitrate levels being much higher than raw water levels. Therefore it is extremely important that the system not be operated beyond design limitations.
An evaluation shall be made to determine if pre-treatment of the water is required if the combination of iron, manganese, and heavy metals exceeds 0.1 milligrams per litre.
Anion exchange units are typically of the pressure type, down flow design. Although a pH spike can typically be observed shortly before bed exhaustion, automatic regeneration based on volume of water treated should be used unless justification for alternate regeneration is submitted to and approved by the reviewing authority. A manual override shall be provided on all automatic controls. A minimum of two units must be provided. The total treatment capacity must be capable of producing the maximum day water demand at a level below the nitrate/nitrite MCL. If a portion of the water is by-passed around the unit and blended with the treated water, the maximum blend ratio allowable must be determined based on the highest anticipated raw water nitrate level. If a by-pass is provided, a totalling metre and a proportioning or regulating device or flow regulating valve must be provided on the by-pass line.
Anion exchange media will remove both nitrates and sulfate from the water being treated. The design capacity for nitrate and sulfate removal expressed as CaCO3 should not exceed 37 g/L when the resin is regenerated with 160 g/L of resin when operating at 0.27 to 0.4 L/min per litre. However, if high levels of chlorides exist in the raw water the exchange capacity of the resin should be reduced to account for the chlorides.
The treatment flow rate should not exceed 17.5 m/hr to 20 m/hr. The back wash flow rate should be 5 m/hr to 7.5 m/hr with a fast rinse approximately equal to the service flow rate.
Adequate freeboard must be provided to accommodate the backwash flow rate of the unit.
The system shall be designed to include an adequate under drain and supporting gravel system, brine distribution equipment, and cross connection control.
Whenever possible, the treated water nitrate/nitrite level should be monitored using continuous monitoring and recording equipment. The continuous monitoring equipment should be equipped with a high nitrate level alarm. If continuous monitoring and recording equipment is not provided, the finished water nitrate/nitrite levels must be determined (using a test kit) no less than daily, preferably just prior to regeneration of the unit.
Generally, waste from the anion exchange unit should be disposed in accordance with Section 9.2 of these Standards. However, prior to any discharge, the reviewing authority must be contacted for wastewater discharge limitations.
Certain types of anion exchange resins can tolerate no more than 0.05 mg/L free chlorine. When the applied water will contain a chlorine residual, the anion exchange resin must be a type that is not damaged by residual chlorine.
Part 1 specifies performance standards for services provided by consulting engineers during the feasibility, pre-design, and design phases of a water works project. The engineer's reports for each phase should be submitted for review and approval prior to the preparation of final, complete, detailed drawings and specifications.
No approval for pre-design or total design can be issued until a final and complete feasibility study has been submitted to the reviewing authority and found to be satisfactory. Permits for construction, for waste discharges, for stream crossings, etc., may be required from other federal, provincial or local regulatory agencies.
According to the phase of the project, documents submitted for formal approval shall include but not be limited to:
Metric (S.I.) units shall be used throughout.
Refer to the INAC document entitled "Practical Guide to Capital Projects" for further details on each phase of the project.
In the event that the water source, and/or the treatment process has not been determined, a feasibility report shall precede the pre-design report and shall include the advantages and disadvantages of each water source under consideration as well as an evaluation of at least two water treatment techniques to render the water potable. A clear recommendation will then be stated in the report on the optimum choice with due consideration to capital costs, O&M costs, life cycle costs, ease of operation and practicality. The reviewed options should include the use of bottled water that would be transported to the community. Give reasons for selecting the option that is recommended, including workers safety, financial considerations, and a comparison of the minimum qualifications of water works operator required for operation of each alternative facility.
The feasibility study shall also include the following general information identified below.
General information should be provided in the feasibility report, including:
Describe the proposed source or sources of water supply to be developed, the reasons for their selection, and provide information as described in Part 3, and as follows:
188.8.131.52 Surface Water Sources
184.108.40.206 Groundwater Sources
After approval of the feasibility study, a pilot study or in-plant demonstration study shall be conducted. The study must be conducted over a sufficient time to treat all expected raw water conditions throughout the year. The study shall emphasize but not be limited to, the following items:
Prior to the initiation of design plans and specifications, a final report including the engineer's design recommendations shall be submitted to the reviewing authority.
The pilot plant filter must be of a similar type and operated in the same manner as proposed for full scale operation.
The pilot study must demonstrate the minimum contact time necessary for optimum filtration for each coagulant proposed.
The pre-design report for water works improvements shall, where pertinent, present the following information:
The pre-design report should include :
Include a description of the following:
Describe the present water system including supply, treatment, storage, and distribution systems. Describe previous water quality problems including any boil water orders if applicable.
Describe the existing wastewater system and sewage treatment works, with special reference to their relationship to existing or proposed water works structures which may affect the operation of the water supply system, or which may affect the quality of the supply.
Summarize and establish the adequacy of proposed processes and unit parameters for the treatment of the specific water under consideration. Include occupational health considerations in this evaluation. Bench scale tests, pilot plant studies, or demonstrations may be required to establish adequacy.
Discuss the various wastes from the water treatment plant, their volume, proposed treatment and points of discharge. If discharging to a sanitary sewerage system, verify that the system, including any lift stations, is capable of handling the flow to the sewage treatment works and that the treatment works is capable and will accept the additional loading.
Provide supporting data justifying automatic equipment, including the servicing and operator training to be provided. Manual override must be provided for any automatic controls. Highly sophisticated automation may put proper maintenance beyond the capability of the plant operator, leading to equipment breakdowns or expensive servicing.
Provide a narrative that describes the proposed operation and control of all pumps and process mechanical equipment. Provide a preliminary process control schematic.
See Section 1.1.4 for required information related to project site.
Include financing considerations as listed in Section 1.1.5.
Summarize planning for future needs and services.
Drawings should be prepared and submitted in discipline order as follows:
Drawings for waterworks improvements shall, where pertinent, provide the following:
Complete, detailed technical specifications shall be supplied for the proposed project, including a program for keeping existing water works facilities in operation during construction of additional facilities so as to minimize interruption of service. Where a groundwater supply will replace a surface water supply, the physical disconnection of the existing surface water supply from the water works must be clearly specified. Specification prepared in the National Master Specification (NMS) format are preferred, including:
A summary of complete design criteria shall be submitted, along with the final design documents for the proposed project, containing but not limited to the following:
aa. Environmental assessment report as dictated in the Canadian Environmental Assessment Act (CEAA) and the Species at Risk Act (SARA).
Any deviations from approved drawings or specifications affecting capacity, hydraulic conditions, operating units, the functioning of water treatment process, or the quality of water to be delivered, must be approved by the reviewing authority before such changes are made. Revised drawings or specifications should be submitted in time to permit the review and approval of such plans or specifications before any construction work, which will be affected by such changes, is begun.
The reviewing authority may require additional information which is not part of the construction drawings, such as head loss calculations, proprietary technical data, copies of deeds, or copies of contracts.
This section describes the desired content of the Operation and Maintenance Manual herein referred to as the Manual.
All material should be bound in a booklet that will allow for removal of pages with originals on white bond paper, and drawings and charts folded to fit within the booklet.
The Manual should include the information listed below if applicable:
The following shall be srepared by the First Nation's professional consulting engineer and submitted as part of the project deliverables when requesting funds for the construction phase:
No longer than two months following final commissioning, the following shall be prepared by the First Nation's professional consulting engineer:
A complete, detailed Emergency Response Plan shall be supplied for the proposed project, along with the final design documents. The Emergency Response Plan should meet the recommendations of the document entitled "Emergency Response Planning for Small Waterworks Systems" published by the Province of British Columbia.
The design of a water supply system or treatment process encompasses a broad area. Application of this part is dependent upon the type of system or process involved.
The system including the water source and treatment facilities shall be designed for maximum day demand at the design year or horizon.
Existing water demand and water leakage must be measured and analyzed during the predesign stage and the results should be included in the engineering report. If previous records spanning over several years are available, they shall be included in the study.
Design the water works to service the community for 10 years with provision for expansion to accommodate a 20 year design. Sustainable engineering principles should be applied when determining the design flow.
The design maximum day demand should not be less than 2.5 times the average day demand.
Trucked water delivery systems shall provide at least 90 litres per person per day.
Design shall consider:
Design shall provide for:
The appropriate regulating authority must be consulted regarding any structure which is so located that normal or flood stream flows may be impeded.
Main switchgear electrical controls shall be located above grade, in areas not subject to flooding or from possible deluge from process piping or equipment. Electrical equipment for processes shall be conveniently located for operation, with direct visual contact, wherever possible with the specific component.
Standby power may be required by the reviewing authority so that water may be treated and/or pumped to the distribution system during power outages to meet the average day demand. The history of power outages, existing and proposed system storage, and current and projected water use shall be reviewed to determine the need for portable, or in-place auxiliary power. Carbon monoxide detectors with alarms are recommended where internal combustion engine driven generators are housed.
Adequate facilities should be included for maintenance shop space and storage consistent with the designed facilities.
Each public water supply shall have its own equipment and facilities for routine laboratory testing necessary to ensure proper plant operation. Laboratory equipment selection shall be based on the characteristics of the raw water source and the complexity of the treatment process involved. The laboratory shall be equipped to meet the applicable Workers' Compensation Board (W.C.B) safety requirements.
Laboratory test kits which simplify procedures for making one or more tests may be acceptable. An operator qualified to perform the necessary laboratory tests is essential. Persons designing and equipping laboratory facilities shall confer with the reviewing authority before beginning the preparation of plans or the purchase of equipment. Methods for verifying adequate quality assurances and for routine calibration of equipment should be provided.
As a minimum, the following laboratory equipment shall be provided:
Sufficient bench space, adequate ventilation, adequate lighting, storage room, laboratory sink, and auxiliary facilities such as an eyewash and deluge shower unit (in accordance with WCB requirements) shall be provided.
Water treatment plants should be provided with equipment (including recorders, where applicable) to monitor the water as follows:
Sample taps consistent with sampling needs shall be provided so that water samples can be obtained from each water source and from appropriate locations in each unit operation of treatment, including a sample from the finished water product. Taps used for obtaining samples for bacteriological analysis shall be of the smooth-nosed type without interior or exterior threads, shall not be of the mixing type, and shall not have a screen, aerator, or other such appurtenance.
The facility potable water supply service line and the plant finished water sample tap shall be supplied from a source of finished water at a point where all chemicals have been thoroughly mixed, and the required disinfectant contact time has been achieved. There shall be no cross-connections between the facility potable water supply service line and the plant non-potable service water, or any piping, troughs, tanks, or other treatment units containing wastewater, treatment chemicals, raw or partially treated water.
Consideration will be given to providing extra wall castings built into the structure to facilitate future uses whenever pipes pass through walls of concrete structures.
All water supplies shall have an acceptable means of metering the finished water.
To facilitate identification of piping in plants and pumping stations it is recommended that the following colour scheme be utilized:
|Settled or Clarified||Aqua|
|Finished or Potable||Dark Blue|
|Alum or Primary Coagulant||Orange|
|Caustic||Yellow with Green Band|
|Chlorine and Solution||Yellow|
|Fluoride||Light Blue with Red Band|
|Polymers or Coagulant Aids||Orange with Green Band|
|Soda Ash||Light Green with Orange Band|
|Ozone||Yellow with Orange Band|
|Backwash Waste||Light Brown|
|Sewer (Sanitary or Other)||Dark Grey|
|Compressed Air||Dark Green|
|Other Lines||Light Grey|
The name of the liquid or gas and arrows indicating the direction of flow should also be on the pipe. In situations where two colours do not have sufficient contrast to easily differentiate between them, a 150 mm band of contrasting colour should be on one of the pipes at approximately 750 mm intervals. The name of the liquid or gas should also be on the pipe. In some cases it may be advantageous to provide arrows indicating the direction of flow.
All wells, pipes, tanks, and equipment which can convey or store potable water shall be disinfected in accordance with current AWWA procedures. Plans or specifications shall outline the procedure and include the disinfectant dosage, contact time, and method of testing the results of the procedure. Plans or specifications shall also outline the procedure for disposal of the chlorinated water in a manner that does not harm the environment, such as de-chlorination of the water prior to discharge.
Equipment containing mercury may not be connected to any liquid system within a water treatment plant where it is possible that mercury may escape into water which subsequently is delivered to consumers.
Design shall consider the plant Operator's safety by meeting all Worker's Compensation Board requirements with particular emphasis to chemicals, rotating equipment, confined space entry, and electrical hazards. Operators should also attend approved courses on WHIMIS and MSDS.
Security measures shall be installed and instituted as required by the reviewing authority. Appropriate design measures to help ensure the security of water system facilities shall be incorporated. Such measures, as a minimum, shall include means to lock all exterior doorways, windows, gates and other entrances to source, treatment and water storage facilities. Other measures may include fencing, signage, close circuit monitoring, realtime water quality monitoring, and intrusion alarms. (See Policy Statement on Security for more details).
Other than surface water intakes, all water supply facilities and water treatment plant access roads shall be protected to at least the 200 year flood elevation or maximum flood of record, as required by the reviewing authority. A freeboard factor may also be required by the reviewing authority.
Chemicals and water contact materials shall be approved by the reviewing authority or meet the appropriate ANSI/AWWA and/or ANSI/NSF Standards. Fluoridation chemicals, if used, should be selected according Health Canada's "Community Water Fluoridation in First Nations and Inuit Communities" (1998).
The plant design and land ownership surrounding the plant shall allow for modifications and expansion of the plant.
Consideration must be given to the design requirements of other federal, provincial, and local regulatory agencies for items such as safety requirements, special designs for the handicapped, plumbing and electrical codes, construction in the flood plain, etc.
In selecting the source of water to be developed, the designing engineer must prove to the satisfaction of the reviewing authority that an adequate quantity of water will be available, and that the water which is to be delivered to the consumers will meet the "Guidelines for Canadian Drinking Water Quality" Latest Edition, published by Health Canada. In order to keep interested parties informed of changes to the Guidelines between publication of new editions, a summary table entitled "Summary of Guidelines for Canadian Drinking Water Quality" is updated and published every spring on Health Canada's website. The "Summary of Guidelines for Canadian Drinking Water Quality supercedes all previous versions, including that contained in the published booklet.
Each water supply should take its raw water from the best available source which is economically reasonable and technically possible.
When a groundwater supply has replaced a surface water supply as the source of water, then the old surface water supply must be physically disconnected from the water system. Any type of connection of the old surface water supply, including the use of a water-main with a closed valve, is not acceptable and will be considered a cross connection.
A surface water source or watershed includes all tributary streams and drainage basins, natural lakes and artificial reservoirs or impoundments above the point of water supply intake. A source water protection plan enacted for continued protection of the watershed from potential sources of contamination shall be provided as determined by the reviewing authority.
The quantity of water at the surface water source shall:
A sanitary survey and study shall be made of the factors, both natural and man made, which could affect quality. Such survey and study shall include, but not be limited to:
220.127.116.11 Intake Structure Design Requirements
Design of intake structures shall provide for:
18.104.22.168 River Intake
River intakes should be sited in a stable reach of the channel, where erosion or deposition will not endanger the works and in such a way that the natural regime of the river will not be upset.
22.214.171.124 Stream-bed Intake
Stream-bed intakes (infiltration galleries) should incorporate either a standby duplicate intake or a submerged intake for use in the event of problems with the stream-bed intake.
When buried surface water collectors are used, sufficient intake opening area must be provided to minimize inlet headloss. Particular attention should be given to the selection of backfill material in relation to the collector pipe slot size and graduation of the native material over the collector system.
126.96.36.199 Off-stream Raw Water Storage Reservoir
The off-stream raw water storage reservoir is a facility into which water is pumped during periods of good quality and high stream flow for future release to treatment facilities. These off-stream raw water storage reservoirs shall be constructed to assure that
188.8.131.52 Site Preparation
Site preparation shall provide where applicable:
184.108.40.206 Approval Requirements
Construction may require:
220.127.116.11 Water Supply Dams
Water supply dams shall be designed and constructed in accordance with the requirements of BC Dam Safety Regulations and the Canadian Dam Association.
For the purpose of this document, a raw water supply which is groundwater means water located in subsurface aquifer(s) where the aquifer overburden and soil act as an effective filter that removes micro-organisms and other particles by straining and antagonistic effect, to a level where the water may already be potable.
Groundwater under the direct influence of surface water (GWUDI) means ground water having incomplete or undependable subsurface filtration of surface water and infiltrating precipitation.
Prior to draft approval of the proposed plan, a quantitative and qualitative evaluation of the groundwater resources at the site shall be made by a professional hydrogeologist or information based on previous studies shall be provided. The evaluation shall include a determination of whether the source is in the category of groundwater under the direct influence of surface water based on the document entitled "Procedure for Disinfection of Drinking Water in Ontario" - Latest Version, Province of Ontario - Section 2.2 of the document.
Additional guidance is available in Section 2 of Ontario Regulation 170/3, and the document entitled "Terms of Reference - Hydrogeological Study to Examine Groundwater Sources Potentially Under Direct Influence of Surface Water" - Latest Version, Province of Ontario, and Section 2 of the document entitled "Guidance Manual for the Surface Water Treatment Rule", USEPA.
Note: The consulting team must balance the scope of the true groundwater determination, or, the groundwater under direct influence (GWUDI) effective in-situ filtration investigation, against the cost of treatment, the time required to conduct the assessment and the various risks to public health. For smaller systems, the team should consider recommending assumption of GWUDI and then design an appropriate surface water treatment process that utilizes any demonstrated in-situ filtration.
Both documents by the Province of Ontario, referenced above, are included in Appendix A.
18.104.22.168 Source Capacity
The total developed groundwater or GWUDI source capacity shall equal or exceed the design maximum day demand and equal or exceed the design average day demand with the largest well out of service.
22.214.171.124 Number of Sources
A minimum of two sources of groundwater or GWUDI is recommended, particularly for remote communities and in larger communities.
126.96.36.199 Stand-by Power
The history of power outages, existing and proposed system storage, and current and projected water use shall be reviewed to determine the need for portable, or in-place auxiliary power.
188.8.131.52 Microbiological Quality
184.108.40.206 Microbiological Quality
220.127.116.11 Radiological Quality
Every new, modified or reconditioned groundwater or GWUDI source shall be examined for radiological activity by tests of a representative sample in a laboratory satisfactory to the reviewing authority to whom the results must be reported.
18.104.22.168 Well Location
The reviewing authority shall be consulted prior to design and construction regarding a proposed well location as it relates to required separation between existing and potential sources of contamination and groundwater development. The optimum well location is to be determined by a professional hydrogeologist. Wells must be located outside the control building, except where line shaft turbines are used.
22.214.171.124 Continued Protection
Continued protection of the well site from potential sources of contamination shall be provided either through ownership, zoning, easements, leasing or other means acceptable to the reviewing authority. Fencing of the site may be required.
126.96.36.199 Wellhead Protection
A wellhead protection area, for continued protection of the wellhead from potential sources of contamination, shall be provided as delineated by the reviewing authority.
Water wells shall be designed, constructed and tested in general accordance with AWWA Standards and relevant provincial guidelines. All wells shall be constructed by BC registered drillers as required by the B.C. Ground Water Protection Regulations.
Of note: wells must be located outside of control buildings except where line shaft turbine is in use.
188.8.131.52 Upper Terminal Well Construction
184.108.40.206 Drilling Fluids and Additives
220.127.116.11 Minimum Protected Depths
Minimum protected depths of drilled wells shall provide watertight construction to such depths as may be required by the B.C. Provincial Regulations and Guidelines, to:
18.104.22.168 Temporary Steel Casing
Temporary steel casing used for construction shall be capable of withstanding the structural load imposed during its installation and removal.
22.214.171.124 Permanent Steel Casing Pipe shall
126.96.36.199 Polyvinyl Chloride Plastic (PVC) Well Casing
The reviewing authority may approve the use of PVC casing for all or for limited applications. Where approved, PVC casing, as a minimum:
188.8.131.52 Other Nonferrous Casing Materials
Packers shall be of material that will not impart taste, odour, toxic substances or bacterial contamination to the well water. Lead packers shall not be used.
184.108.40.206 Grouting Requirements
All permanent well casing shall be surrounded to a minimum of 40 mm of grout to the depth required by the reviewing authority. Other forms of grouting may be approved for driven casing. All temporary construction casings shall be removed. Where removal is not possible or practical, the casing shall be withdrawn at least 1.5 metres to ensure grout contact with the native formation.
220.127.116.11 Capping Requirements
18.104.22.168 Tagging Requirements
Phase I of the BC Ground Water Protection Regulations stipulates tagging requirements for newly completed or closed wells. The requirements are summarized below:
22.214.171.124 Well Abandonment
126.96.36.199 Yield and Draw-down Tests
188.8.131.52 Plumbness and Alignment Requirements
184.108.40.206 Geological Data
Geological data shall:
220.127.116.11 Retention of Records
The owner of each well shall retain all records pertaining to each well, until the well has been properly abandoned.
18.104.22.168 Line Shaft Pumps
Wells equipped with line shaft pumps shall
22.214.171.124 Submersible Pump
Where a submersible pump is used:
126.96.36.199 Discharge Piping
188.8.131.52 Pitless Well Units
184.108.40.206 Casing Vent
Provisions shall be made for venting the well casing to atmosphere. The vent shall terminate in a down-turned position, at or above the top of the casing or pitless unit in a minimum 40 mm diameter opening covered with a #16 mesh, corrosion resistant (usually stainless steel) screen. The pipe connecting the casing to the vent shall be of adequate size to provide rapid venting of the casing.
220.127.116.11 Water Level Measurement
18.104.22.168 Observation Wells
22.214.171.124 Sand or Gravel Wells
126.96.36.199 Gravel Pack Wells
188.8.131.52 Radial Water Collector
184.108.40.206 Infiltration Lines
220.127.116.11 Dug Wells
18.104.22.168 Limestone or Sandstone Wells
22.214.171.124 Naturally Flowing Wells
Water which is to be delivered to consumers must meet the "Guidelines for Canadian Drinking Water Quality" Latest Edition, published in a booklet by Health Canada. In order to keep interested parties informed of changes to the Guidelines between publication of new editions, a summary table entitled "Summary of Guidelines for Canadian Drinking Water Quality" is updated and published every spring on Health Canada's website . The "Summary of Guidelines for Canadian Drinking Water Quality" supercedes all previous versions, including that contained in the published Health Canada booklet.
The design of treatment processes and devices shall depend on an evaluation of the nature and quality of the particular water to be treated, seasonal variations, the desired quality of the finished water and the mode of operation planned. Continuous disinfection is required for all water supplies.
Water containing high turbidity may require pretreatment, usually coagulation, flocculation and clarification with the addition of coagulation chemicals. Water containing colour greater than 15 True Colour Units (TCU), or Total Organic Carbon (TOC) in a concentration that it may produce disinfection by-products during disinfection with chlorine may require pre-treatment with the addition of coagulation chemicals.
As per Health Canada Guidelines for Canadian Drinking Water Quality - Supporting Documentation on Turbidity - for chemically assisted filtration (i.e., continuous feed of a coagulant with mixing ahead of filtration), source water turbidity levels should be measured at least once per calendar day directly in front of where the first treatment chemical is applied.
The above notwithstanding all designs should provide for low mechanical content to the greatest extent possible. For example, water systems and processes based on flow of water by gravity are preferred over pumped or mechanical systems.
The design shall prevent cross connections, and common walls, between potable and nonpotable water.
Where the drinking water system obtains water from a raw water supply which is groundwater, the treatment process must, as a minimum, consist of disinfection and must be credited with achieving an overall performance that provides at least 2-log (99%) inactivation or removal of viruses before water is delivered to the first consumer.
Where the drinking water system obtains water from a raw water supply which is groundwater that is of questionable sanitary quality, the treatment process shall as a minimum, consist of disinfection and must be credited with achieving an overall performance that provides at least 4-log (99.99%) inactivation or removal of viruses before water is delivered to the first consumer.
Plants designed for processing groundwater with treatment other than disinfection shall be designed according to the applicable process descriptions noted further in this Section Part 4. The process shall provide a level of treatment which achieves at least 4-log (99.99%) inactivation or removal of viruses.
Primary disinfection processes that do not produce a disinfection residual must be followed by a secondary disinfectant. The use of chlorine as secondary disinfection by applying chlorine to provide a residual disinfectant is recommended.
Filtration and Disinfection may be required for all surface water, and groundwater under the direct influence of surface water. Disinfection is mandatory and will ideally include two distinct stages, a primary stage using pH UV irradiation to inactivate or destroy bacteria, protozoa and some viruses and a secondary stage using chlorine to complete the destruction of potential pathogens and maintain a working residual in the distribution system.
Filtration is required at all treatment plants unless the avoidance criteria for filtration is met as detailed in the Health Canada Guidelines for Canadian Drinking Water Quality - Supporting Documentation on Turbidity. Filtration of a surface water source or a groundwater source under the direct influence of surface water may not be necessary if all of the following conditions are met:
Water treatment facilities designed for processing surface water, and groundwater under the direct influence of surface water shall be designed according to the applicable and/or pertinent treatment process described later in this Part 4. The following minimum level of treatment for microbiological contaminants shall be provided:
|Cryptosporidium||2 log (99%)|
|Giardia||3 log (99.9%)|
|Viruses||4 log (99.99%)|
At least 0.5-log removal or inactivation of Giardia cysts, and 2-log removal or inactivation of viruses must be provided through the disinfection portion of the overall water treatment process.
The requirements of the document entitled "Procedure for Disinfection of Drinking Water in Ontario" - Latest Version, Province of Ontario, should be met for determining whether water treatment facilities provide the minimum level of treatment for microbiological contaminants. The document is available in Appendix A.
The following treatment processes and devices are included as guidelines that will depend on the nature and quality of the raw water to be treated. Such treatment when selected as the preferred option must ensure that the treated water complies fully with the latest edition of the Guidelines for Canadian Drinking Water Quality and the criteria noted under 4.1 and 4.2 above for microbiological removal or inactivation.
The treatment processes addressed in this document are:
Water containing high turbidity may require pre-treatment, usually sedimentation with or without the addition of coagulation chemicals:
126.96.36.199 Rapid Mix
Rapid mix shall mean the rapid dispersion of chemicals throughout the water to be treated, usually by violent agitation. The engineer shall submit the design basis for the velocity gradient (G value) selected, considering the chemicals to be added, water temperature, colour and other related water quality parameters.
Flocculation shall mean the agitation of water at low velocities for long periods of time.
Sedimentation shall follow flocculation. The detention time for effective clarification is dependent upon a number of factors related to basin design and the nature of the raw water. The following criteria apply to conventional sedimentation units:
188.8.131.52 Plate Settlers
Proposals for settler unit clarification must include pilot plant and/or full scale demonstration data on water with similar quality prior to the preparation of final plans and specifications for approval. Settler units consisting of variously shaped plates which are installed in multiple layers and at an angle to the flow may be used for sedimentation, following flocculation.
184.108.40.206.1 General Criteria
Acceptable filters shall include, upon the discretion of the reviewing authority, the following types:
The application of any one type must be supported by water quality data representing a reasonable period of time to characterize the variations in water quality. Experimental treatment studies may be required to demonstrate the applicability of the method of filtration proposed.
220.127.116.11 Rapid Rate Gravity Filters
The use of rapid rate gravity filters shall require pre-treatment.
18.104.22.168.2. Rate of Filtration
The rate of filtration shall be determined through consideration of such factors as raw water quality, degree of pre-treatment provided, filter media, water quality control parameters, competency of operating personnel, and other factors as required by the reviewing authority. In any case, the filter rate must be proposed and justified by the design engineer to the satisfaction of the reviewing authority prior to the preparation of final plans and specifications.
At least two units shall be provided. Where only two units are provided, each shall be capable of meeting the plant design capacity (normally the projected maximum daily demand) at the approved filtration rate. Where more than two filter units are provided, the filters shall be capable of meeting the plant design capacity at the approved filtration rate with one filter removed from service. Where declining rate filtration is provided, the variable aspect of filtration rates, and the number of filters must be considered when determining the design capacity for the filters.
22.214.171.124.4. Structural Details and Hydraulics
The filter structure shall be designed to provide for:
126.96.36.199.5. Wash-water Troughs
Wash-water troughs shall be constructed to have:
188.8.131.52.6. Filter Material
The media shall be clean silica sand or other natural or synthetic media free from detrimental chemical or bacterial contaminants, approved by the reviewing authority, and having the following characteristics:
|60 mm to 50 mm||125 mm to 200 mm|
|50 mm to 20 mm||75 mm to 125 mm|
|20 mm to 10 mm||75 mm to 125 mm|
|10 mm to 5 mm||50 mm to 75 mm|
|5 mm to 2.5 mm||50 mm to 75 mm|
184.108.40.206.7. Filter Bottoms and Strainer Systems
Departures from these standards may be acceptable for high rate filters and for proprietary bottoms. Porous plate bottoms shall not be used where iron or manganese may clog them. The design of manifold-type collection systems shall;
220.127.116.11.8. Surface Wash or Subsurface Wash
Surface or subsurface wash facilities are required except for filters used exclusively for iron or manganese removal, and may be accomplished by a system of fixed nozzles or a revolving-type apparatus. All devices shall be designed with:
18.104.22.168.9. Air Scouring
Air scouring can be considered in place of surface wash:
Provisions shall be made for washing filters as follows:
Roof drains shall not discharge into the filters or basins and conduits preceding the filters.
22.214.171.124 Rapid Rate Pressure Filters
The normal use of these filters is for iron and manganese removal. Pressure filters shall not be used in the filtration of surface or other polluted water.
Minimum criteria relative to rate of filtration, structural details and hydraulics, filter media, etc., provided for rapid rate gravity filters also apply to pressure filters where appropriate.
126.96.36.199.2. Rate of Filtration
The rate shall not exceed 7.2 m/hr except where in plant testing as approved by the reviewing authority has demonstrated satisfactory results at higher rates.
188.8.131.52.3. Details of Design
The filters shall be designed to provide for:
184.108.40.206 Slow Sand Filters
The use of these filters shall require prior engineering studies to demonstrate the adequacy and suitability of this method of filtration for the specific raw water supply.
For conditions not included in this guideline, or at the direction of the reviewing authority, engineering studies should include operation of a pilot plant in order to determine the suitability of the proposed sand and to establish the required frequency of cleaning. The pilot plant should use the same sand as proposed for the full scale plant and the period of operation should include seasons with poor water quality conditions.
220.127.116.11.1. Quality of Raw Water
Slow sand gravity filtration shall be limited to water having maximum turbidities of 10 NTU's and maximum colour of 15 TCU; turbidity values must not be attributable to colloidal clay. Raw water quality data must include examinations for algae. These conditions pertain to raw water without coagulation pre-treatment.
Slow sand gravity filtration with coagulation pre-treatment (enhanced treatment) should have influent water to the filter with a maximum turbidity of 2 NTU and a maximum colour of 15 TCU.
At least two units shall be provided in order to allow operation flexibility unless waived by the reviewing authority.
18.104.22.168.3. Structural Details and Hydraulics
Slow sand gravity filters shall be so designed as to provide:
22.214.171.124.4. Rates of Filtration
The permissible rates of filtration shall be determined by the quality of the raw water and shall be on the basis of experimental data derived from the water to be treated;
126.96.36.199.6. Filter Material
188.8.131.52.7. Filter Gravel
184.108.40.206.8. Depth of Water on Filter Beds
220.127.116.11.9. Control Appurtenances
Turbidity test equipment must also be provided for measurement of raw water turbidity. The following shall be provided for each filter unit:
Slow sand filters shall be operated to waste after scraping or rebedding during a ripening period until the filter effluent turbidity falls to consistently below 5 NTU.
18.104.22.168 Direct Filtration
Direct filtration, as used herein, refers to the filtration of a surface water following chemical coagulation and possibly flocculation but without prior settling. The nature of the treatment process will depend upon the raw water quality. A full scale direct filtration plant shall not be constructed without prior pilot studies which are acceptable to the reviewing authority. In-plant demonstration studies may be appropriate where conventional treatment plants are converted to direct filtration. Where direct filtration is proposed, an engineering report shall be submitted prior to conducting pilot plant or inplant demonstration studies.
22.214.171.124 Siting Requirements
See Section 2.20.
Disinfection is required for all raw water supplies, regardless of source. The required amount of primary disinfection needed shall be specified by the reviewing authority. Continuous disinfection is required for all water supplies. Consideration must be given to the formation of disinfection byproducts (DBP) when selecting the disinfectant.
Disinfection shall be accomplished using chlorine or ultraviolet light or if considered necessary by both. Chlorine is the preferred disinfecting agent and may be introduced into the water supply using either sodium or calcium hypochlorite. If calcium hypochlorite is used then the tablet form is preferred. (See Part 5 for further details of disinfecting agents).
126.96.36.199 Chlorination Equipment
Hypochlorite feeders of the positive displacement type or in tablet form must be provided depending on the hypochlorite selected (see Part 5).
188.8.131.52.2. Design Capacity
The chlorination system must be able to provide a free chlorine residual of at least 2 mg/L once all demands are met after a contact time of at least 30 minutes under anticipated maximum chlorine demand conditions. The initial chlorine metering pumps should be designed for twice the maximum demand that will be achieved at the plant five years following pump installation. Every five years the feeder pumps should be replaced with pumps of higher capacity to meet twice the maximum day demand that will be reached five years after installation. The capacity of the replacement feeder pumps would increase until the plant design capacity has been reached. This will allow the pumps to operate more effectively during the low flows the plant will experience during the initial years of plant operation. The replacement of the feeder pumps every five years with greater capacity pumps must be included in maintenance cost estimates for treatment facilities (See Section 1.1.5).
184.108.40.206.3. Standby Equipment
Where chlorination is required for protection of the supply, standby equipment of sufficient capacity shall be available to replace the largest unit. Spare parts shall be made available to replace parts subject to wear and breakage.
The chlorine solution injector/diffuser must be compatible with the point of application to provide a rapid and thorough mix with all the water being treated. The centre of a pipeline is the preferred application point.
220.127.116.11 Contact Time and Point of Application
18.104.22.168 Residual Chlorine
Free residual chlorination is the preferred practice. The overall waterworks should be capable of achieving, at all locations within the distribution system, a free chlorine residual of at least 0.2 milligrams per litre. Higher residuals may be required depending on pH, temperature and other characteristics of the water;
22.214.171.124 Testing Equipment
126.96.36.199 Chlorinator Piping
188.8.131.52.1. Cross-connection Protection
The chlorinator water supply piping shall be designed to prevent contamination of the treated water supply by sources of questionable quality.
184.108.40.206.2. Pipe Material
See Part 5 for further details.
See Part 5 for further details.
220.127.116.11 UV Disinfection
UV (ultraviolet light) disinfection may be considered as an alternative primary disinfectant if accepted by the reviewing authority. In order to be acceptable, the UV system must meet the following minimum requirements:
NOTE: In the near future the USEPA will be publishing UV dosage tables and a UV Guidance Manual for UV disinfection of drinking water.
18.104.22.168 Other Disinfecting Agents
Proposals for use of disinfecting agents other than those listed shall be approved by the reviewing authority prior to preparation of final plans and specifications. Although disinfecting agents other than chlorine are available, each can have shortcomings when applied to a small community water supply.
Only ion-exchange softening will be considered and where approved by the reviewing authority. Consideration must be taken into account for the disposal of brine wastes in accordance with the reviewing authority.
22.214.171.124 Cation Exchange Process
Alternative water sources should be investigated when the sodium content and dissolved solids concentration is of concern with respect to health (low sodium diets).
126.96.36.199.1. Pre-treatment Requirements
Iron, manganese, or a combination of the two, should not exceed 0.3 mg/L in the water as applied to the ion exchange resin. Pre-treatment is required when the content of iron, manganese, or a combination of the two is one milligram per litre or more. Water having 5 NTU's or more turbidity should not be applied directly to the cation exchange softener.
The units may be of pressure or gravity type, of either an upflow or down-flow design. Automatic regeneration based on volume of water softened should be used unless manual regeneration is justified and is approved by the reviewing authority. A manual override shall be provided on all automatic controls.
188.8.131.52.3. Exchange Capacity
The design capacity for hardness removal should not exceed 46 kg/m3 when resin is regenerated with 0.14 kg of salt per kg of hardness removed.
184.108.40.206.4. Depth of Resin
The depth of the exchange resin should not be less than 1 m.
220.127.116.11.5. Flow Rates
The rate of softening should not exceed 17 m/hr and the backwash rate should be 14-20 m/hr of bed area. Rate-of-flow controllers or the equivalent must be installed for the above purposes.
The freeboard will depend upon the size and specific gravity of the resin and the direction of water flow. Generally, the wash-water collector should be 600 mm above the top of the resin on down-flow units.
18.104.22.168.7. Under-drains and Supporting Gravel
The bottoms, strainer systems and support for the exchange resin shall conform to criteria provided for rapid rate gravity filters.
22.214.171.124.8. Brine Distribution
Facilities should be included for even distribution of the brine over the entire surface of both upflow and down-flow units.
126.96.36.199.9. Cross-connection Control
Backwash, rinse and air relief discharge pipes shall be installed in such a manner as to prevent any possibility of back-siphonage.
188.8.131.52.10. Bypass Piping and Equipment
A bypass must be provided around softening units to produce a blended water of desirable hardness. Totalizing metres must be installed in the bypass line and on each softener unit. The bypass line must have a shut-off valve and should have an automatic proportioning or regulating device. In some installations, it may be necessary to treat the bypassed water to obtain acceptable levels of iron and/or manganese in the finished water.
184.108.40.206.11. Additional Limitations
Silica gel resins should not be used for water having a pH above 8.4 or containing less than six milligrams per litre of silica and should not be used when iron is present. When the applied water contains a chlorine residual, the cation exchange resin shall be a type that is not damaged by residual chlorine. Phenolic resin should not be used.
220.127.116.11.12. Sampling Taps
Smooth-nose sampling taps must be provided for the collection of representative samples. The taps shall be located to provide for sampling of the softener influent, effluent and blended water. The sampling taps for the blended water shall be at least 6 m downstream from the point of blending. Petcocks are not acceptable as sampling taps. Sampling taps should be provided on the brine tank discharge piping.
18.104.22.168.13. Brine and Salt Storage Tanks
22.214.171.124.14. Salt and Brine Storage Capacity
Total salt storage should have sufficient capacity to store in excess of 1-1/2 carloads or truckloads of salt, and provide for at least 30 days of operation.
126.96.36.199.15. Brine Pump or Eductor
An eductor may be used to transfer brine from the brine tank to the softeners. If a pump is used, a brine measuring tank or means of metering should be provided to obtain proper dilution.
188.8.131.52.16. Waste Disposal
Suitable disposal must be provided for brine waste (see Part 9). Where the volume of spent brine must be reduced, consideration may be given to using a part of the spent brine for a subsequent regeneration.
184.108.40.206.17. Construction Materials
Pipes and contact materials must be resistant to the aggressiveness of salt. Plastic and red brass are acceptable piping materials. Steel and concrete must be coated with a non-leaching protective coating which is compatible with salt and brine.
Bagged salt and dry bulk salt storage shall be enclosed and separated from other operating areas in order to prevent damage to equipment.
220.127.116.11 Water Quality Test Equipment
Test equipment for alkalinity, total hardness, carbon dioxide content, and pH should be provided to determine treatment effectiveness.
Aeration may be used to help remove offensive tastes and odours due to dissolved gases from decomposing organic matter, or to reduce or remove objectionable amounts of carbon dioxide, hydrogen sulfide, etc. and to introduce oxygen to assist in iron and/or manganese removal. The packed tower aeration process is an aeration process applicable to removal of volatile organic contaminants.
18.104.22.168 Natural Draft Aeration
Design shall provide:
22.214.171.124 Forced or Induced Draft Aeration
Devices shall be designed to:
126.96.36.199 Spray Aeration
Design shall provide:
188.8.131.52 Pressure Aeration
Pressure aeration may be used for oxidation purposes only if pilot plant study indicates the method is applicable; it is not acceptable for removal of dissolved gases. Filters following pressure aeration must have adequate exhaust devices for release of air. Pressure aeration devices shall be designed to:
184.108.40.206 Packed Tower Aeration
Packed tower aeration (PTA) which is also known as air stripping involves passing water down through a column of packing material while pumping air counter-currently up through the packing. PTA is used for the removal of volatile organic chemicals, trihalomethanes, carbon dioxide, and radon. Generally, PTA is feasible for compounds with a Henry's Constant greater than 100 (expressed in atm mol/mol) - at 12EC, but not normally feasible for removing compounds with a Henry's Constant less than 10. For values between 10 and 100, PTA may be feasible but should be extensively evaluated using pilot studies. Values for Henry's Constant should be discussed with the reviewing authority prior to final design.
220.127.116.11.1. Process Design
18.104.22.168.2. Materials of Construction
22.214.171.124.3. Water Flow System
126.96.36.199.4. Air Flow System
188.8.131.52.5. Other Features that shall be provided:
184.108.40.206.5. Other Features that shall be provided:
220.127.116.11.6. Environmental Factors
18.104.22.168 Other Methods of Aeration
Other methods of aeration may be used if applicable to the treatment needs. Such methods include but are not restricted to spraying, diffused air, cascades and mechanical aeration. The treatment processes must be designed to meet the particular needs of the water to be treated and are subject to the approval of the reviewing authority.
22.214.171.124 Protection of Aerators
All aerators except those discharging to clarification plants shall be protected from contamination by birds, insects, wind borne debris, rainfall and water draining off the exterior of the aerator.
Groundwater supplies exposed to the atmosphere by aeration must receive chlorination as the minimum additional treatment.
A bypass should be provided for all aeration units except those installed to comply with maximum contaminant levels.
126.96.36.199 Corrosion Control
The aggressiveness of the water after aeration should be determined and corrected by additional treatment, if necessary.
188.8.131.52 Quality Control
Equipment should be provided to test for DO, pH and temperature to determine proper functioning of the aeration device. Equipment to test for iron, manganese, and carbon dioxide should also be considered.
Iron and manganese control, as used herein, refers solely to treatment processes designed specifically for this purpose. The treatment process used will depend upon the character of the raw water. The selection of one or more treatment processes must meet specific local conditions as determined by engineering investigations, including chemical analyses of representative samples of water to be treated, and receive the approval of the reviewing authority. It may be necessary to operate a pilot plant in order to gather all information pertinent to the design. Consideration should be given to adjusting pH of the raw water to optimize the chemical reaction. Testing equipment and sampling taps shall be provided as outlined in Part 2.
184.108.40.206 Removal by Oxidation, Detention and Filtration
Oxidation may be aeration, as indicated in Section 4.3.5, or by chemical oxidation with chlorine with due consideration to the raw water pH, the total organic carbon in the raw water, and the potential formation of THM's.
Filters shall be provided and shall conform to the applicable section in this part of the guidelines.
220.127.116.11 Removal by Silica Sand/Manganese Coated Media Filtration
This process consists of a continuous chlorine or other approved oxidizing agent to the influent of a silica sand/manganese coated media filter. Due consideration must be taken into account of the formation of THM's.
18.104.22.168 Removal by Ion Exchange
This process of iron and manganese removal should not be used for water containing more than 0.3 milligrams per litre of iron, manganese or combination thereof. This process is not acceptable where either the raw water or wash water contains dissolved oxygen or other oxidants.
Fluoridation shall be applied to a community water system if a referendum or plebiscite has been held in the community and the majority of eligible voters have voted to have it included as a prophylactic in the public water system. Fluoride when introduced into the water system has been found to have beneficial effects on children in their teeth and bone forming years.
22.214.171.124 Fluoride dosage
Accurate dosage of the fluoride ion is important and should be based on seasonal influences with approximately 0.7 mg/L of fluoride ion being added during the summer months and a maximum of 1 mg/L of fluoride ion being added during the other three seasons.
126.96.36.199 Fluoride Chemicals
The following three chemicals are considered suitable as commercially available feed chemicals for the application of fluoride:
Consideration must be taken into account of the following parameters when selecting the appropriate chemical: the purity of the chemical, the percentage of fluoride ion in each kilogram of chemical, the solubility of the chemical in the solution water and the comparative costs.
All or any of the above chemicals when added to a public water supply will tend to depress the pH and increase the aggressive nature of the water. This is particularly important for many west coast water where the water is only lightly buffered. Therefore consideration should be taken into account with due regard to corrosion on distribution piping ( old asbestos cement piping) and domestic plumbing before proceeding with fluoridation or selecting the appropriate chemical to apply fluoridation.
188.8.131.52 Fluoride feed equipment
See Part 5 for further details of feed equipment for fluoride systems.
184.108.40.206 Other Standards
For other guidelines on fluoridation systems see the April 1999 Fluoridation Design Manual for Water Systems in B.C. Region.
Water that lacks alkalinity for coagulation treatment or is unstable, aggressive and/or corrosive due to previous or subsequent treatment shall be conditioned to improve coagulation or stabilized to reduce corrosion effects
220.127.116.11 Alkali Feed
Water with low alkalinity or pH should be treated with percolating lime rock contactors or the application of an alkali chemical, such as sodium hydroxide (caustic soda) or sodium carbonate (soda ash). See below for details of limestone contactors and Part 5 for sodium hydroxide and sodium carbonate systems.
18.104.22.168 Limestone Contactor
Limestone contactors may be required prior to pre-treatment of the raw water (primary limestone contactor) to provide sufficient alkalinity for coagulation, or after the chlorine contact tank (secondary limestone contactor) for corrosion control. The following general design guidelines are provided for both limestone contactors, followed by special provisions for the primary and secondary limestone contactors.
22.214.171.124.1. General Limestone Contactor Design Guidelines
126.96.36.199.2. Special Considerations for Primary Limestone Contactor
188.8.131.52.3. Special Considerations for Secondary Limestone Contactor
The following specifies requirements for the supply, installation and testing of limestone for the limestone contactor(s):
184.108.40.206 Other Treatment
Other treatment for controlling corrosive water by the use of calcium hydroxide, sodium hydroxide and sodium carbonate may be used where necessary. Any proprietary compound must receive the specific approval of the reviewing authority before use. Chemical feeders shall be as required in Part 5.
Unstable water resulting from the bacterial decomposition of organic matter in water (especially in dead end mains), the biochemical action within tubercles, and the reduction of sulfates should be prevented by the maintenance of a free and/or combined chlorine residual throughout the distribution system.
Laboratory equipment shall be provided for determining the effectiveness of stabilization treatment.
Provision shall be made for the control of taste and odour at all surface water treatment plants. Chemicals shall be added sufficiently ahead of other treatment processes to assure adequate contact time for an effective and economical use of the chemicals. Where severe taste and odour problems are encountered, in-plant and/or pilot plant studies are required.
Acceptable treatment processes for taste and odour control are as follows:
Plants treating water that is known to have taste and odour problems should be provided with equipment that makes several of the control processes available so that the operator will have flexibility in operation.
Chlorination can be used for the removal of some objectionable odours. Adequate contact time must be provided to complete the chemical reactions involved. Excessive potential trihalomethane production through this process should be avoided by adequate bench-scale testing prior to design.
220.127.116.11 Granular Activated Carbon
Replacement of anthracite with GAC may be considered as a control measure for geosmin and methyl isoborneol (MIB) taste and odours from algae blooms. Demonstration studies performed by the Consulting Engineer may be required by the reviewing authority.
See Section 18.104.22.168.6 (Filter Material) for application within filters.
See Section 4.3.5.
22.214.171.124 Other Methods
The decision to use any other methods of taste and odour control should be made only after careful laboratory and/or pilot plant tests and approval by the reviewing authority.
A microscreen is a mechanical supplement of treatment capable of removing suspended matter from the water by straining. It may be used to reduce nuisance organisms and organic loadings. It shall not be used in place of:
Arsenic removal, as used herein, refers to treatment processes specifically related to reducing levels of arsenic below 0.025 mg/L in the treated water and preferably below 0.010 mg/L. Where raw water systems exceed 0.025 mg/L of arsenic then every effort should be made to locate an alternative raw water source or, if there is no other source available in the localized area then a treatment strategy must be planned to effectively reduce the total arsenic level to preferably below 0.010 mg/L.
126.96.36.199 Pilot Plant
A pilot plant will be necessary to determine the optimum form of treatment to be applied to site specific water, a complete protocol of the pilot work must be developed and submitted to the reviewing authority before the pilot work and testing commences. All pilot work and testing will be done in-situ close by the actual source of the raw water.
Aqueous arsenic solutions are generally most prevalent in the trivalent and pentavalent states, each species in turn predominating as a function of the pH of the water. The trivalent species predominates as a weak acid in the pH range of 2 to 9, while the pentavalent species occurs as a strong acid. The disassociation properties and the pH of the treated water are therefore important criteria in the conventional coagulation process in the selection of the appropriate treatment process. The following treatment processes may be considered for the removal of arsenic:
Not all the above treatment options are pH dependent, but where they are, consideration should be given to raising or depressing the pH of the raw water to suit the selected process with the appropriate chemical.
188.8.131.52 Rejects and Waste Streams
Adsorption media once spent will be replaced and not generated, the spent material shall be disposed of in suitable landfills with the approval of the reviewing authorities. Backwash streams or rejects from RO systems may be discharged to the sewer or to septic tanks with the approval of the reviewing authority.
184.108.40.206 Treatment Criteria
The selected treatment option shall take into consideration the required complexity of operation, the capital costs, operation and maintenance costs and the life cycle costs. A minimum of two treatment processes shall be piloted following a desktop study which identifies the pilot program and the protocol to follow.
220.127.116.11 Testing Equipment
Analytical testing equipment and proper laboratory procedures shall be included in the pilot plant and final prototype to accurately measure the levels of arsenic in the raw and treated water.
No chemicals shall be applied to treat drinking water unless specifically permitted by the reviewing authority. Chemicals shall meet requirements of NSF 60. Commercially available chemical solutions are preferred.
Plans and specifications shall be submitted for review and approval as provided for in Part 1, and shall include:
Chemicals shall be applied to the water at such points and by such means as to:
General equipment design shall be such that:
Number of Feeders
Positive displacement type solution feed pumps should be used to feed liquid chemicals. Pumps must be sized to match or exceed maximum head conditions found at the point of injection.
Liquid chemical feeders shall be such that the solution cannot be siphoned into the water supply, by:
Cross-connection control must be provided to assure that:
Chemical feed equipment shall:
In-plant water supply (if required) shall be:
Chemical shipping containers shall be fully labelled to meet MSDS standards to include:
Chemicals shall be approved by the reviewing authority or meet the appropriate ANSI /AWWA standards and/or ANSI/NSF Standard 60.
Provisions may be required to verify the properties, purity, and content of chemicals delivered.
Special provisions shall be made for ventilation of chlorine feed and storage rooms to meet the BC Workers' Compensation Board requirements. The Chlorine room shall be fan force air exhausted by ducting from a point 300 mm above the floor level.
Respiratory protection equipment shall meet the Workers' Compensation Board.
Protective equipment, including emergency eyewash facilities, shall be provided, and shall meet the requirements of the Workers' Compensation Board.
Sodium hypochlorite storage and handling procedures should be arranged to minimize the slow natural decay process either by contamination or by exposure to more extreme storage conditions. In addition, feed rates should be regularly adjusted to compensate for this progressive loss in chlorine content.
The following three chemicals should be considered as being suitable to add fluoride ion to a drinking water supply:
18.104.22.168 Sodium Fluoride and Sodium Silicofluoride
22.214.171.124 Hydrofluosilicic Acid
126.96.36.199 Other Standards
For other guidelines on fluoridation systems see the April 1999 Fluoridation Design Manual for Water Systems in B.C. Region.
Pumping facilities shall be designed to maintain the potable quality of pumped water. Subsurface pits or pump rooms and inaccessible installation should be avoided. No pumping station shall be subject to flooding.
The pumping station shall be so located that the proposed site will meet the requirements for sanitary protection of water quality, hydraulics of the system and protection against interruption of service by fire, flood or any other hazard.
The station will be:
Both raw and finished water pumping stations shall:
Suction wells shall:
Pump stations shall be provided with:
Stairways or ladders shall:
Provisions shall be made for adequate heating for:
In pump houses not occupied by personnel, only enough heat need be provided to prevent freezing of equipment or impairment of the treatment process.
Ventilation shall conform to existing provincial and/or federal codes. Adequate ventilation shall be provided for all pumping stations. Forced ventilation of at least six changes of air per hour shall be provided for:
In areas where excess moisture could cause hazards to safety or damage to equipment, means for dehumidification should be provided.
Pump stations shall be adequately lighted throughout. All electrical work shall conform to the requirements for the Canadian Electrical Code (latest edition).
At least two pumping units shall be provided. With any pump out of service, the remaining pump or pumps shall be capable of providing the maximum daily pumping demand of the system. The pumping units shall:
Suction lift shall:
If suction lift is necessary, provision shall be made for priming the pumps.
Prime water must not be of lesser sanitary quality than that of the water being pumped. Means shall be provided to prevent back siphonage. When an air-operated ejector is used, the screened intake shall draw clean air from a point at least 3 metres above the ground or other source of possible contamination, unless the air is filtered by an apparatus approved by the reviewing authority. Vacuum priming may be used.
Booster pumps shall be located or controlled so that:
Each booster pumping station should contain not less than two pumps with capacities such that peak hourly demands can be satisfied with the largest pump out of service. Consideration should be given for installing pumps only designed for the first ten year design horizon initially. Pump replacement must be included in life-cycle cost estimates for the treatment facilities (see Section 1.1.5).
All booster pumping stations shall include a flow indicator and flow totalizer meter and provide an analogue signal suitable for input to a SCADA system or data logger.
In addition to the other requirements of this section, in-line booster pumps shall be accessible for servicing and repairs.
A fire pump should be provided in a water system when adequate pressure or quantity is not available to supply the fire flow requirements.
Where practical, it is preferred practice to provide the fire flow by means of an elevated tank. This eliminates maintenance requirements of diesel engine driven fire pumps, and provides much greater reliability.
It is recommended that, when fire pumps constitute the sole or primary water supply for fire protection purposes on large systems, at least two fire pumps be installed.
All fire pumps and drive units are to be installed and tested according to the requirements of ULC and NFPA 20, Standard for the Installation of Centrifugal Fire Pumps.
Diesel engine or electric motors are acceptable types of fire pump drivers. If other pump drivers are considered by the designer, it must be demonstrated that they will meet an acceptable performance standard similar to NFPA 20. Acceptable two-pump arrangements (where applicable) are:
Pumps shall be adequately valved to permit satisfactory operation, maintenance and repair of the equipment. If foot valves are necessary, they shall have a net valve area of at least two and one half times the area of the suction pipe and they shall be screened. Each pump shall have a positive-acting check valve on the discharge side between the pump and the shut-off valve.
Surge relief valves or slow acting check valves should be designed to minimize hydraulic transients.
All piping 50 mm in diameter or smaller is recommended to be AISI 316 or 416 stainless steel. Piping larger than 50 mm in diameter could also be stainless steel, if preferred by the professional engineer. In general, piping shall:
The term "lead free" when used with respect to solders and flux refers to solders and flux containing not more than 0.2% lead. The term "lead free" when used with respect to pipes and pipe fittings refers to pipes and pipe fitting containing not more than 8.0% lead.
Each pump shall have:
The station should have indicating, totalizing, and recording metering of the total water pumped. Flow meters should provide a signal suitable for input to a SCADA system and/or a data logger. A satisfactory straight section of pipe shall be installed upstream and downstream of the meter in accordance with the meter manufacturer's recommendations to improve accuracy where required.
Water seals shall not be supplied with water of a lesser sanitary quality than that of the water being pumped. Where pumps are sealed with potable water and are pumping water of lesser sanitary quality, the seal shall:
Pumps, their prime movers and accessories, shall be controlled in such a manner that they will operate at rated capacity without dangerous overload. Where two or more pumps are installed, provision shall be made for automatic alternation. Provision shall be made to prevent energizing the motor in the event of a backspin cycle. Electrical controls shall be located above grade. Equipment shall be provided or other arrangements made to prevent surge pressures from activating controls which switch on pumps or activate other equipment outside the normal design cycle of operation.
When power failure would result in cessation of minimum essential service, power supply should be provided from at least two independent sources, or a standby or an auxiliary source shall be provided.
If standby power is provided by onsite generators or engines, the generators shall be specified to have their own integral fuel storage. The installation must comply with the latest edition of the Installation Code for Oil-Burning Equipment (CSA-B139). If installed outside, the generator and integral fuel storage must be installed on a concrete pad to prevent spills from entering the ground. The concrete pad shall extend a minimum of 0.6 metres beyond the location of the fuel tank fill pipe.
The fuel storage capacity shall be sufficient to provide a minimum 24 hours operation at full load. As a conservative estimate, generators can be considered to produce 3 kWh per litre of fuel consumed. Therefore, for a 35 kW generator, a reasonable fuel storage amount for a 24 hour period could be calculated as:
Note that this assumes operation at full load; the amounts for ½ loads or ¼ loads are not directly proportional.
The fuel storage compartment on the generator shall be double-walled. The interstitial space on the fuel storage shall be monitored and alarmed to indicate if there is a leak in the interstitial space. Overfill protection of the tanks may be provided in the form of visual monitoring of the fuel level in the storage tank by employees in constant attendance throughout the transfer operation, who are located so as to be able to promptly shut down the flow. Spill response equipment, such as absorbent pads, should be stored in a weatherproof container near the generator.
When automatic pre-lubrication of pump bearings is necessary and an auxiliary direct drive power supply is provided, the pre-lubrication line shall be provided with a valved bypass around the automatic control so that the bearings can, if necessary, be lubricated manually before the pump is started or the pre-lubrication controls shall be wired to the auxiliary power supply.
Where a well pumping station and chlorine and/or chemical system is to be installed, the preferred layout is for a three-room building which includes a separate chlorine or chemical room, pump room and electrical room. Access to the chlorine or chemical room will be from the outside only with a viewing window between the pump room and chlorine or chemical room. See the construction sketch in Appendix C for more details.
The materials and designs used for treated water storage structures shall provide stability and durability as well as protect the quality of the stored water. Water storage tanks are typically made of concrete or steel. Steel structures shall follow the current AWWA standards concerning steel tanks, standpipes, reservoirs, and elevated tanks wherever they are applicable. When steel tanks are used, the owner of the treatment plant is responsible for ensuring that the tanks are cleaned every three to five years and prior to inspections. It is preferable that the manufacturer provide facilities for internal cleaning.
Equipment containing mercury may not be connected to any liquid system within a water storage facility where it is possible that mercury may escape into water which subsequently is delivered to consumers.
Storage facilities shall have sufficient capacity, as determined from engineering studies, to meet domestic demands (equalization), emergency demands, and where fire protection is provided, fire flow demands. Emergency supply is required in case of events such as power outages and restriction in source capacity.
|Fire Flow Required (L/s)||Duration (Hours)|
|Interpolate for intermediate figures.
(Note: this table is based on the publication "Water Supply for Public Fire Protection", Latest Edition by Fire Insurer's Advisory Organization.)
When locating water storage facilities, consideration should be given to maintaining water quality. The bottom of reservoirs and stand-pipes should be placed at the normal ground surface and shall be above the 200 year flood or the highest flood of record. If the bottom of the reservoirs is below normal ground surface, then sewers, drains, standing water, and similar sources of possible contamination must be kept at least 15 metres from the reservoir. Water main pipe, pressure tested in place to 340 kPa without leakage, may be used for gravity sewers at distances greater than 6 m but less than 15 m from the reservoir.
All water storage structures shall have suitable watertight roofs which exclude birds, animals, insects, and excessive dust. Appurtenances such as antenna must be installed in a manner that ensures that damage to the tank, coatings or water quality is avoided, or that damage that has occurred is corrected.
Fencing, locks on access manholes, and other necessary precautions shall be provided to prevent trespassing, vandalism, and sabotage.
No drain on a water storage structure may have a direct connection to a sewer or storm drain. The design shall allow draining the storage facility for cleaning or maintenance without causing loss of pressure in the distribution system. The water storage site and adjacent land shall be protected from erosion due to the draining of the storage tank. When bolted or welded steel tanks are used the tank supplier shall make provisions for cleaning the tanks.
System should be designed to facilitate turnover of water in the reservoir. Separate inlet and outlet pipes, as well as means to avoid stagnation and thermal stratification while encouraging mixing should be considered. Where baffles are installed in the reservoir, their purpose should only be to improve T10/T ratios in order to meet or exceed regulation CT targets for microbiological inactivation or destruction, as per the CT tables shown in Appendix A.
All water storage structures shall be provided with an overflow which is brought down to an elevation between 300 mm and 600 mm above the ground surface, and discharges over a drainage inlet structure or a splash plate. No overflow may be connected directly to a sewer or a storm drain. All overflow pipes should be located so that any discharge is visible.
Access shall be provided to the interior for inspection, cleaning and maintenance. At least two (2) manholes shall be provided above the waterline at each compartment where space permits.
Steel welded tanks require an opening near the access ladder and an additional opening at the roof centre. Dimensional requirements are specified in AWWA Standard D100. Additional openings may be required for ventilation during painting. Access to bolted steel tanks will adhere to AWWA Standard D103.
Water storage structures shall be vented. Refer to Appendix C for concept drawing. Overflows shall not be considered as vents. Open construction between the sidewall and roof is not permissible. Vents for reservoirs:
At least one of the vents on steel welded tanks must be located near the centre of the roof.
The roof and sidewalls of all structures must be watertight with no openings except properly constructed vents, manholes, overflows, risers, drains, pump mountings, control ports, or piping for inflow and outflow.
The roof of the storage structure shall be well drained. Down spout pipes shall not enter or pass through the reservoir. Parapets, or similar construction which would tend to hold water and snow on the roof, will not be approved unless adequate waterproofing and drainage are provided.
The material used in construction of reservoirs shall be acceptable to the reviewing authority. Porous material, including wood and concrete block, are not suitable for potable water contact applications.
The safety of employees must be considered in the design of the storage structure. As a minimum, such matters shall conform to pertinent laws and regulations of Canada and the relevant province.
All finished water storage structures and their appurtenances, especially the riser pipes, overflows, and vents, shall be designed to prevent freezing which will interfere withproper functioning. Equipment used for freeze protection that will come into contact with the potable water shall meet ANSI/NSF Standard 61 or be approved by the reviewing authority. If a water circulation system is used, it is recommended that the circulation pipe be located separately from the riser pipe.
Every catwalk over finished water in a storage structure shall have a solid floor with raised edges so designed that shoe scrapings and dirt will not fall into the water.
The discharge pipes form all reservoirs shall be located in a manner that will prevent the flow of sediment into the distribution system. Removable silt stops should be provided.
The area surrounding a ground-level structure shall be graded in a manner that will prevent surface water from standing within 15 m of it.
Proper protection shall be given to metal surfaces by paints or other protective coatings, by cathodic protective devices, or by both.
Appropriate sampling tap(s) shall be provided to facilitate collection of water samples for both bacteriologic and chemical analyses.
Inspection of bolted and welded steel tanks shall follow AWWA Standard D100 and should conform to the guidelines given in AWWA Standard D101. The First Nations owner of the treatment facilities should retain a local contractor who is experienced in the inspection and clean-out of reservoirs to conduct the inspection. The Circuit Rider should also routinely verify that the internal condition of water storage tanks in the community is satisfactory. Expenses associated with the inspections must be incorporated into the cost estimates specified in Section 1.1.5.
The applicable design standards of Section 7.0 shall be followed for plant storage.
Filter washwater tanks shall be sized, in conjunction with available pump units and finished water storage, to provide the backwash water required by Section 188.8.131.52.11. Consideration must be given to the backwashing of several filters in rapid succession.
Clearwell storage should be sized, in conjunction with distribution system storage, to relieve the filters from having to follow fluctuations in water use.
Finished water must not be stored or conveyed in a compartment adjacent to untreated or wastewater of any kind when the two compartments are separated by a single wall.
Other treatment plant storage tanks/basins such as detention basins, backwash reclaim tanks, receiving basins and pump wet-wells for finished water shall be designed as treated water storage structures.
Hydro-pneumatic (pressure) tanks, when provided as the only water storage, are acceptable only in very small water systems. Hydro-pneumatic tank storage is not to be permitted for fire protection purposes. Pressure tanks shall meet ASME Sections 8 and 9 of the Boiler and Pressure Vessel Code, as well as relevant Provincial requirements and regulations for the construction and installation of unfired pressure vessels.
The tank shall be located above normal ground surface and be completely housed.
The hydro-pneumatic tank(s) shall have bypass piping to permit operation of the system while the tanks is being repaired or painted.
Each tank shall have an access manhole, a drain, and control equipment consisting of a pressure gauge, water sight glass, automatic or manual air blow-off, means for adding air, and pressure operated start-stop controls for the pumps. Where practical the access manhole shall be 600 millimetres in diameter.
In addition to the preceding standards the following shall apply for distribution system storage:
The minimum pressure during peak hourly demand in the distribution system shall be 275 kPa. When pressures exceed 760 kPa, pressure reducing devices shall be provided on mains in the distribution system. Pressure in house plumbing should not exceed 550 kPa. (See the section entitled "Water Main Design" for minimum pressure during fire flow.)
Storage structures which provide pressure directly to the distribution system shall be designed so they can be isolated from the distribution system and drained for cleaning or maintenance without necessitating loss of pressure in the distribution system. The drain shall discharge to the ground surface with no direct connection to a sewer or storm drain.
Adequate controls shall be provided to maintain levels in distribution system storage structures.
Water distribution systems shall be designed to maintain treated water quality. Special consideration should be given to distribution main sizing, providing for design of multidirectional flow, adequate valving for distribution system control, and provisions for adequate flushing. Systems should be designed to maximize turnover and to minimize residence times.
All water mains, including those not designed to provide fire protection, shall be sized after a hydraulic analysis based on flow demands and pressure requirements. Under conditions of simultaneous maximum day and fire flow demands, the pressure shall not drop below 140 kPa (with the exception that, at locations where non-residential sprinkler systems for fire protection are necessary, additional residual pressure conditions are required; as explained below. The pressure in the distribution system during peak hourly demand must not be less than 275 kPa.
The minimum size of water main for providing fire protection and serving fire hydrants shall be 150 mm diameter. Larger size mains may be required to allow the withdrawal of the required fire flow while maintaining the minimum residual pressure of 140 kPa.
If the water supply system is designed to provide fire protection capability, then system design should address major fire risks projected for the community (or service area) within the 20 year design life of the waterworks.
Water mains not designed to carry fire-flows shall not have fire hydrants connected to them.
Dead ends should be minimized by looping of all mains whenever practical. Make provision for maintaining a minimum flow of water where necessary to maintain water quality. This is commonly referred to as provision for "bleeding" of water.
Where dead-end mains occur they shall be provided with an approved blow-off or self draining stand pipe for flushing purposes. Flushing devices should be sized to provide flows which will give a velocity of at least 0.7 metres per second in the water main being flushed. No flushing device shall be directly connected to any sewer.
A means to easily facilitate the cleaning of the interior surface of water mains (such as installing launch points for conducting swabbing or pigging of water mains) should be provided in rural long-distance low-flow pipelines where it is not practical to obtain adequate cleaning with flushing alone.
Sufficient sectional valves shall be provided on water mains so that inconvenience and sanitary hazards will be minimized during repairs. Valves should be located at not more the 150 metres intervals in commercial districts and at not more than one block or 240 metre intervals in other districts. Where systems serve widely scattered customers and where future development is not expected the valve spacing should not exceed 1,800 m.
A rock plate should be installed on valve riser stem at a distance of 300 mm below ground surface. Refer to Appendix C for concept drawings.
Fire hydrants should have a bottom valve size of at least 125 mm and two 63 mm outlets. In those cases where a pumper outlet may be required, the pumper outlet diameter shall match the pumper suction inlet diameter. Outlet threads shall be compatible with the available fire fighting equipment.
The hydrant lead shall be a minimum of 150 mm in diameter. Auxiliary valves shall be installed in all hydrant leads.
At sites subject to a seasonally high groundwater table, hydrant drains shall be plugged. When the drains are plugged the barrels must be pumped dry after use during freezing weather. Where hydrant drains are not plugged, a gravel pocket or dry well shall be provided unless the natural soils will provide adequate drainage. Hydrant drains shall not be connected to or located within 3 metres of sanitary sewers, or storm drains. The hydrant shall have provision for plugging or unplugging the drain hole from the ground surface without excavation.
Refer to Appendix C for concept drawing.
At high points in water mains where air can accumulate provisions shall be made to remove the air by means of hydrants or air relief valves. Automatic air relief valves shall not be used in situations where flooding of the manhole or chamber may occur.
The open end of an air relief pipe from automatic valves shall be extended to at least 300 mm above grade and provided with a 16 mesh screened, downward-facing elbow.
The pipe from a manually operated valve should be extended to the top of the pit. Use of manual air relief valves is recommended where ever possible. Discharge piping from air relief valves shall not connect directly to any storm drain, storm sewer or sanitary sewer.
Chambers, pits or manholes containing valves, blow-offs, meters, or other such appurtenances to a distribution system, shall not be connected directly to any storm drain or sanitary sewer. Such chambers or pits shall be drained to the surface of the ground where they are not subject to flooding by surface water, or to absorption pits underground (if soil conditions are suitable) at sites not subject to a seasonally high groundwater table.
Refer to Appendix C for concept drawing.
Specifications shall incorporate the provisions of the AWWA standards and/or manufacturer's recommended installation procedures.
A continuous and uniform bedding shall be provided in the trench for all buried pipe. Backfill material shall be tamped in layers around the pipe and to a sufficient height above the pipe to adequately support and protect the pipe. Stones found in the trench shall be removed for a depth of at least 150 mm below the bottom of the pipe.
All water mains shall be covered with sufficient earth or other insulation to prevent freezing.
All tees, bends, plugs and hydrants shall be provided with reaction blocking, tie rods or joints designed to prevent movement.
All types of installed pipe shall be pressure tested and leakage tested in accordance with the latest edition of AWWA Standard C600.
All new, cleaned or repaired water mains shall be disinfected in accordance with AWWA Standard C651. The specifications shall include detailed procedures for the adequate flushing, disinfection, and microbiological testing of all water mains. In an emergency or unusual situation, disinfection procedure shall be discussed with the reviewing authority.
The following are recommended steps to determine the degree of external corrosion. See the relevant Policy Statement on this subject at the front of this document.
The following factors should be considered in providing adequate separation:
Water mains shall be laid at least 3 metres horizontally from any existing or proposed sewer or septic tank adsorption field trench. The distance shall be measured edge to edge. In cases where it is not practical to maintain a 3 metres separation, the reviewing authority may allow deviation on a case-by-case basis, if supported by data from the design engineer. Such deviation may allow installation of the water main closer to a sewer, provided that the water main is laid in a separate trench or on an undisturbed earth shelf located on one side of the sewer at such an elevation that the bottom of the water main is at least 0.45 metres above the top of the sewer.
Water mains crossing sewers shall be laid to provide a minimum vertical distance of 0.45 metres between the outside of the water main and the outside of the sewer. This shall be the case where the water main is either above or below the sewer with preference to the water main above the sewer. At crossings, one full length of water pipe shall be located so both joints will be as far from the sewer as possible. Special structural support for the water and sewer pipes may be required.
The reviewing authority must specifically approve any variance from the requirements of Sections 8.7.2 and 8.7.3 when it is impossible to obtain the specified separation distances. Where separation distances cannot be met, the sewer materials shall be waterworks grade 1.0 Mpa pressure rated pipe, or equivalent, and shall be pressure tested for water tightness.
No water pipe shall pass through or come in contact with any part of a sewer manhole. Water mains should be located at least 3 metres from sewer manholes.
Surface water crossings, whether over or under water, present special problems. The reviewing authority should be consulted before final plans are prepared.
The pipe shall be adequately supported and anchored, protected from damage and freezing, and accessible for repair or replacement.
A minimum cover of 600 mm shall be provided over the pipe. When crossing water courses which are greater than 5 metres in width, the following shall be provided:
There shall be no connection between the distribution system and any pipes, pumps, hydrants, or tanks whereby unsafe water or other contaminating materials may be discharged or drawn into the system.
When a groundwater supply has replaced a surface water supply as the source of water, then the surface water supply must be physically disconnected from the water system.
Any type of connection of the surface water supply, including the use of valves is not acceptable.
Neither steam condensate nor cooling water from engine jackets or other heat exchange devices shall be returned to the potable water supply.
The approval of the reviewing authority shall be obtained for interconnections between potable water supplies. Consideration should be given to differences in water quality.
In order to provide adequate flow for operation of the sprinklers in single family houses the minimum pipe diameter should be as follows:
* If service length exceeds 50 m or if the highest house ceiling is more than 7 metres above ground surface (at water main location) or if a flow meter is to be installed on the service line, then the required diameter of water service shall be determined using NFPA- 13D. Refer to Appendix C for concept drawing.
The diameter of services to provide adequate flow for operation of sprinklers in multi- family dwellings shall be based on NFPA-13 and NFPA-13D.
Individual booster pumps shall not be allowed for any individual service from the public water supply mains. Where permitted for other types of services, booster pumps shall be designed in accordance with Section 6.4.
Separation of sewer and water services from the main to the house should meet regional procedures.
On each water service from a street main to a building an approved gate valve and valve box shall be installed between the property line and the curb. Combination stop and waste valves shall not be installed underground in water service piping.
Each service connection should be individually metered if control of consumption is required to conserve a limited water supply quantity.
Where meters are installed on services which provide flows for residential sprinkler systems, the water service and flow meters shall meet the provisions of NFPA - 13D.
Water loading stations present special problems since the fill line may be used for filling both potable water vessels and other tanks or contaminated vessels. To prevent contamination of both the public supply and potable water vessels being filled, the following principles shall be met in the design of water loading stations:
Vehicles and mechanisms for trucked water shall conform to the relevant federal and provincial standards and regulations for water vending.
All waste discharges shall be governed by the applicable regulatory agency requirements. The requirements outlined herein must, therefore, be considered minimum requirements as environmental and water pollution control authorities may have more stringent requirements.
Provisions must be made for proper disposal of water treatment plant wastes, such as sanitary, laboratory, clarification sludge (aluminum hydroxide), ferrous hydroxide sludge, filter backwash water and brines. In locating waste disposal facilities, due consideration shall be given to preventing potential contamination of the raw water supply.
Alternative methods of water treatment and chemical use should be considered as a means of reducing waste volumes and the associated handling and disposal problems.
Appropriate backflow protection must be provided on waste discharge piping as needed to protect the public water supply.
The sanitary waste from water treatment plants, pumping stations, and other waterworks installations must receive treatment. Waste from these facilities shall be discharged directly to a sanitary sewer system, when available and feasible, or to an adequate on-site waste treatment facility approved by the appropriate reviewing authority.
Waste from ion exchange plants, demineralization plans, or other plants which produce a brine, may be disposed of by controlled discharge to a stream if adequate dilution is available. Surface water quality requirements of the regulatory agency will control the rate of discharge. Except when discharging to large waterways, a holding tank of sufficient size should be provided to allow the brine to be discharged over a twenty-four hour period. Where discharging to a sanitary sewer, a holding tank may be required to prevent the overloading of the sewer and/or interference with the waste treatment processes. The effect of brine discharge to sewage lagoons may depend on the rate of evaporation from the lagoons.
Lagooning may be used as a method of handling aluminum hydroxide sludge. Lagoon size can be calculated using total chemicals used plus a factor for turbidity. Freezing changes the nature of aluminum hydroxide sludge so that it can be used for landfill.
Aluminum hydroxide sludge may also be discharged to a sanitary sewer. However, initiation of this practice will depend on obtaining approval from the owner of the sewerage system as well as from the regulatory agency before final designs are made.
Lagoons should be designed to produce an effluent satisfactory to the regulatory agency and should provide for:
Aluminum hydroxide sludge may be disposed of by land application either alone, or in combination with other wastes where an agronomic value has been determined and disposal has been approved by the reviewing authority.
Waste filter wash water from iron and manganese removal plants can be disposed of as follows:
Waste filter wash water from iron and manganese removal plants can be disposed of as follows:
Lagoons shall have the following features:
Red water can be discharged to a community sewer. However, approval of this method will depend on obtaining approval from the owner of the sewerage system as well as from the regulatory agency before final designs are made. A holding tank is recommended to prevent overloading the sewers. Design shall prevent cross connections and there shall be no common walls between potable and non-potable water.
Recycling of supernatant or filtrate from "red water" waste treatment facilities to the head end of an iron removal plant shall not be allowed except as approved by the reviewing authority.
Filter backwash water from surface water treatment plants should have suspended solids reduced to a level acceptable to the regulatory agency before being discharged to any receiving stream in accordance with the CEPA. Many plants have constructed holding tanks and returned this water to the inlet end of the plant. The holding tank shall be of such a size that it will contain the anticipated volume of waste wash water produced by the plant when operating at design capacity. A plant that has two filters should have a holding tank that will contain the total waste wash water from both filters calculated by using a 15 minute wash at 50 m/hr. In plants with more filters, the size of the holding tank will depend on the anticipated hours of operation. It is recommended that waste filter wash water be returned at a rate of less than 10% of the instantaneous raw water flow rate enter the plant.
Filter backwash water shall not be recycled when the raw water contains excessive algae, when finished water taste and odour problems are encountered, or when disinfection byproduct levels in the distribution system may exceed allowable levels. Particular attention must be given to the presence of protozoans such as Giardia and Cryptosporidium concentrating in the waste water stream. Water Treatment Plans will be required to treat filter waste water prior to recycling or avoid reclaiming filter wash water given the increased risk to treated water quality.
Radioactive materials include, but are not limited to, granulated activated carbon (GAC) used for radon removal; ion-exchange regeneration waste from radium removal; and manganese greensand backwash solids from manganese removal systems, and reverse osmosis concentrates where radiological constituents are present. The buildup of radioactive decay products of radon shall be considered, and adequate shielding and safeguards shall be provided for operators and visitors. These materials may require disposal as radioactive waste in accordance with Nuclear Regulatory Commission regulations. Approval shall be obtained from the responsible regulatory agencies prior to disposal of all wastes.
Spent sand shall be disposed of in an appropriate manner and in an area in conformance with CEPA requirements.
Spent lime rock shall be disposed of in an appropriate manner and in an area in conformance to the CEPA.
Toxic laboratory wastes shall be drained to a separate holding tank and disposed of at a toxic waste facility or the local sewage plant.
All floor drains shall be discharged to the sewer or to the plant wastewater holding ponds.
All rejects from the membrane process shall be discharged to the sewer or to the plant wastewater holding ponds.
Available at :
|Automatic Sprinkler Systems Handbook, Third Edition, 1987 NFPA||National Fire Protection Association|
|AWWA Standards||American Water Works Association|
|BC Water Protection Act, 1996||Ministry of Management Services|
|Canadian Environmental Assessment Act, 1992||Department of Justice Canada|
|Emergency Response Planning for Small Waterworks Systems. Government of British Columbia.||Government of British Columbia, Ministry of Health Planning|
|Emergency Response Planning for Small Waterworks Systems. Government of British Columbia.||Government of British Columbia, Ministry of Small Waterworks Systems. Health Planning|
|First Nations Water and Wastewater Management Strategy, Indian and Northern Affairs Canada, B.C. Region||Indian and Northern Affairs Canada, B.C.|
|Fluoridation Design Manual for Water Systems in B.C. Region, April 1999, Indian and Northern Affairs Canada, B.C. Region.||Indian and Northern Affairs Canada, B.C.|
|From Source to Tap: Guidance on the Multi-Barrier Approach to Safe Drinking Water, 2004, Canadian Council of Ministers of the Environment||Canadian Council of Ministers of the Environment|
|Guidelines for Canadian Drinking Water Quality - Sixth Edith, 1996||Health Canada|
|National Primary Drinking Water Regulation, July 2002, USEPA||US Government Printing Office|
|NFPA13D Standard for the Installation of Sprinkler Systems in One and Two Family Dwellings and Mobile Homes||National Fire Protection Association|
|NFPA20 Standard for the Installation of Centrifugal Fire Pumps||National Fire Protection Association.|
|Procedure for Disinfection of Drinking Water in Ontario. Government of Ontario||Government of Ontario|
|Recommended Standards for Water Works - 2003. Committee of the Great Lakes - Upper Mississippi River Board of State Public Health and Environmental Managers.||Health Education Services|
|Slow Sand Filtration 1974 Huisman and Wood, World Health Organization.||Canadian Public Health Association|
|Slow Sand Filtration for Community Water Supply - Planning, Design, Construction, Supply - Planning, Design, Construction, Operation, and Maintenance, 1987||International Reference Centre|
|Small Community Water Supplies, Hofkes, E.H.||John Wiley & Sons|
|Standard Methods of the Examination for Water and Wastewater||American Water Works Association|
|Summary of Guidelines for Canadian Drinking Water Quality||Health Canada|
|Terms of Reference - Hydrogeological Study to Examine Groundwater Sources Potentially Under Direct Influence of Surface Water, Ontario.||Government of Ontario|
|USEPA Guidance Manual for the Surface Water Treatment Rule, March 1991 Edition||USEPA|
|INAC’s Practical Guide to Capital Projects||From INAC’s Funding Services Directorate in BC Region. 604-666-5171|
|BC’s Drinking Water Protection Act||Government of British Columbia, Ministry of Health Services|
|BC’s Drinking Water Protection Regulation||Government of British Columbia, Ministry of Health Services|
|BC’s Groundwater Protection Regulation||Government of British Columbia, Ministry of Environment|
|AWWA||American Water Works Association|
|NFPA||National Fire Protection Association|
|NSF||National Sanitation Foundation|
|NTU||Nephelometric Turbidity Unit|
|mg/L||Milligrams per litre|
|L/s||Litres per second|
|m/s||metres per second|
|GAC||granular activated carbon|
|m/h||metres per hour|
|m/min||metres per minute|
The drawings on the following pages have been prepared to provide practical information towards the provision of water works and water supply facilities. Their purpose is to minimize design time and expense, capital, operating and maintenance costs and to maximize system reliability and efficiency.
The drawings are to be used as a basis for detailed design and are not intended to be used in Contract Documents as detail drawings. Every effort has been made to ensure that all details and information is correct on each of the drawings, however "site specific" conditions and individual requirements will dictate the use of sound engineering judgment and good practice in the proper application of these plans to each specific application.