For use in the Denver Water Service Area |
The Board Of Water Commissioners
Denver Water
Engineering Standards
Chapter 6 – Materials
6.01 Materials And Testing:
Detailed technical specifications for purchase or approval of materials are included in the Materials Specifications of these Standards. All materials shall conform to the Materials Specifications and to all limitations on acceptable makes and styles.
Materials furnished shall be new and undamaged. Everything necessary to complete installations in accordance with the Engineering Standards of Denver Water shall be furnished and installed whether shown on approved drawings or not; and installations shall be completed as fully operable, functioning parts of the Denver water system.
Where mains are extended by Applicants, it shall be their responsibility to provide all materials necessary for the installation. No materials will be supplied to the Applicant by Denver Water.
Acceptance of materials, or the waiving of inspection thereof, shall in no way relieve the Applicant of the responsibility for furnishing materials meeting the requirements of the Materials Specifications.
New water industry products or materials will be tested if it is the opinion of the Engineer that the product or material has some merit. Denver Water will establish the criteria for testing and evaluating the product. Denver Water reserves the right to accept or reject any product or material regardless of the test results. See Appendix A, Procedure For Evaluation Of Materials.
6.02 Size Of Mains:
The size of mains shall be in accordance with 5. Standard acceptable nominal diameters of distribution mains are 4, 6, 8, and 12 inches. Standard acceptable nominal diameters of transmission mains are 16and 20 inches. Standard acceptable nominal diameters for conduits are 24 inches and larger.
6.03 Pipe Classes:
Denver Water has established minimum design safety factors for system piping considering working pressures of 150 psi concurrent with water hammer surge pressure of 120 psi for 4, 6, and 8 inch pipe, 110 psi for 12 inch pipe and 70 psi for l6 inch and larger pipe.
Based upon these considerations, the following minimum AWWA Standard pressure classes for acceptable types of pipe are required:
| Ductile Iron (DI) | - | Special Class 50 (6, 8, l2 & l6 inch) |
| Special Class 51 (4, 20 & 24 inch) | ||
| Plastic (PVC) | - | Class 150 (6, 8 & 12 inch) |
| Class 200 (4 inch) | ||
6.04 Selection Of Pipe:
In general, selection of type of pipe shall be left to the discretion of the Professional Engineer in charge of design. However, Denver Water reserves the right to deny use of certain types of materials in specific circumstances.
Where joint restraint is required, the designer shall select a pipe together with an approved system of restraint. It should be noted that installation of any metallic pipe, rods, clamps, etc. in corrosive soil areas will require corrosion protection systems.
Installation of mains through tunneled crossings such as at railroads, highways, canals, etc., will require the selection of metallic pipe with approved joint restraint systems. Bridge hangings will also require selection of metallic pipe with joint restraint.
Installation of mains at airports, through hazardous areas, at depths greater than 10 feet and in the roadways of State and Federal highways may require the selection of pressure classes in excess of the minimum stated in 6.03. Special comprehensive studies of applicable laws, regulations, and detailed engineering calculations shall be submitted for review by Denver Water in these instances.
Whenever the installation of metallic pipe is contemplated, a soil resistivity survey of the construction area shall be performed. The survey data and calculations, together with the service history of other existing pipe in the area, shall be submitted to Denver Water. Resistivity surveys shall utilize the Wenner four-pin method. Denver Water will provide the resistivity surveys, free of charge, on request. This service will also be provided when installing non-metallic pipe in order to determine if protection is needed for metallic fittings and appurtenances.
When water mains are to be constructed in soils that have a resistivity of less than 1,000 ohm-centimeters, or where stray current corrosion is expected to be severe, an approved non-metallic pipe system shall be selected. When water mains are to be constructed in soils that have a resistivity of more than 1,000 ohm-centimeters, either metallic or non-metallic pipe material may be selected. All metallic pipe, joint restraint, fittings, tie rods and appurtenances, regardless of soil resistivity, shall be protected against corrosion by polyethylene wrap in accordance with 8.24.
* See 10.06 for Special Class 50 alternate for 24 inch.
6.05 Pipe Fittings:
A. Joints: Joints and fittings shall conform to the applicable AWWA Standards, and shall bear at least the pressure rating of the straight pipe involved. Acceptable types for straight lengths of pipe are push-on and mechanical joint. Mechanical joints for straight lengths of pipe will be allowed only under specific situations receiving approval of Denver Water.
Within the City and County of Denver and Total Service Contract Areas, all fittings shall be furnished with mechanical joint ends and shall conform to MS-3. Private pipe extensions may use mechanical joint or push-on joint fittings and otherwise shall conform to MS-3. Exception: Fire hydrant tees shall be mechanical joint ends. Flanged joints are permitted where specified in the Materials Specifications.
The use of wyes is strictly prohibited.
B. Closure Fittings: Bolted Sleeve Type Couplings in accordance with AWWA C219 shall be of a gasketed, sleeve-type, with diameter to properly fit the pipe. Tolerance on pipe and coupling, together with proper bolt and gasket arrangements, shall be sufficient to insure permanent watertight joints under all conditions. Couplings shall be sufficiently wide, so that each type of pipe joined will have as much pipe end inserted in the couplings as is provided by the standard push on or mechanical joint for the pipe size and type involved.
The following table contains the minimum center sleeve dimensions for bolted sleeve type couplings:
| Pipe Diameter (Inches) | Center Sleeve Thickness (Inches) | Center Sleeve Width (Inches) | ||
|---|---|---|---|---|
| 4 | 0.250 | 5 | ||
| 6 | 0.250 | 5 | ||
| 8 | 0.250 | 5 | ||
| 12 | 0.375 | 7 | ||
| 16 | 0.375 | 7 | ||
| 20 | 0.375 | 7 | ||
| 24 | 0.375 | 7 |
Cast or ductile iron sleeves shall have mechanical joints of the proper size and tolerance to assure a water tight fit.
"Long bell" closure pieces shall be of at least equal strength to the straight pipe being joined and shall contain push on joints of the proper tolerance to insure watertight connections.
"Compression" fittings for small diameter pipe (less than 3 inch diameter) may be utilized for connection or repair only with approval of Denver Water.
Where pipes of different types are connected together, or where pipe is connected to fittings or valves of different materials, great care shall be taken to insure that the proper ring, insulating gasket, or adapter is selected.
C. Miscellaneous Pipe Fittings: Flanged adapters, plugs, end caps, bulkheads, cut-in sleeves, anchor couplings, repair fittings, and other appurtenances shall be used where appropriate throughout the system, subject to the approval of Denver Water. Denver Water does not intend to limit unreasonably, the installation of any type of fitting, joint, or proprietary device, however, the installation of any such fitting, not specifically approved by these Standards, is subject to the approval of Denver Water. Written request for approval of deviating items shall be made in advance through Denver Water.
D. Clamps, Rods and Joint Restraint Devices: Harnessing of joints may be accomplished either by use of the clamp and rod system shown on Sheets 21 through 26 of the Standard Drawings, or by use of one of the mechanical joint restraint systems as shown on Sheet 27 or 28 of the Standard Drawings, and specified in MS-27, or by use of one of the several proprietary joint restraint systems supplied by pipe manufacturers. The proprietary systems will require approval of Denver Water prior to use. Regardless of the system used, restrained lengths of pipe for various fittings, where harnessing is utilized or required, shall be at least equal to the lengths shown on Sheet 21 of the Standard Drawings. Details and materials of clamps, rods and nuts, washers, rod couplings, and flange lugs used by Denver Water are shown on the Standard Drawings.
Where joint restraint is required on PVC pipe, the designer may use a joint restraint system of the type supplied by pipe manufacturers and approved by Denver Water or switch to a metallic pipe and use rods and clamps. The use of rods and clamps on PVC pipe is not allowed unless specific approval is granted by Denver Water.
6.06 Line Valves:
Line valves shall be gate valves conforming to MS-4 or Resilient Seat Gate Valves, as specified in MS-4A. The valves shall be of the same size as the main. Valves shall open to the right (clockwise). Valves with operators which open to the left (counterclockwise) shall not be used, unless required by or approval is obtained from Denver Water.
6.07 Pressure Regulating Valves:
A pressure regulating valve (PRV) is used for keeping downstream pressure at a uniform pressure less than that in the upstream main.
Pressure regulating valves shall conform to MS-9. They shall be sized so that the velocity through the valve at maximum demand does not exceed 25 feet per second. If a wide range of flow rates is anticipated, more than one valve may be required. Care shall be taken to ensure adequate pressure differential across the valve under all ranges of flow to accomplish hydraulic throttling. When pressure differentials greater than 45 psi are expected, or when the downstream pressure will be low relative to the differential, special valve materials or a special valve design may be required.
Pressure regulating valves shall be properly supported, and shall have an adequate clearance above and below the valve to facilitate servicing. A manual bypass is required for all single valve installations. Telemetering of data may be required. Each PRV shall have a gate valve on each side for isolation. General arrangement shall be as shown on Sheets 43 through 46 of the Standard Drawings.
6.08 Tapping Valves And Sleeves:
A tapping valve and sleeve are used together to tap an existing main that is in service and under pressure, without interrupting service. A tapping valve does not replace a property line valve, which shall be required in addition to the tapping valve. A property line valve may not be required if a main's out-distance is 15 feet or less.
Connections 2 inches and smaller to mains shall be by a corporation stop of the same size as the service line.
Connections larger than 2 inches made to mains shall be either by an existing tee, by cutting a tee into a dewatered line if permitted by Denver Water, or by use of a tapping valve and a tapping sleeve. Whichever method is used, care shall be exercised to select sleeves and gaskets which are properly sized to fit the type and class of pipe to be tapped. Where tapping sleeves larger than 2 inches are used, a thrust block shall be formed and placed behind the tapping valve to prevent possible damage to the main from pressure shocks, which develop as valves are first opened. Tapping sleeves shall conform to MS-8. Thrust blocks shall conform to Sheet 19 of the Standard Drawings.
6.09 Check Valves:
A check valve permits flow in one direction only, closing when the flow stops so that no reversal can occur. Check valves shall conform to MS-6. They shall be used where shown in typical meter installation. They are otherwise prohibited unless specifically approved by Denver Water. Check valves shall be located in concrete manholes of the same specifications as required for PRV manhole installations as shown on Sheets 43 through 46 of the Standard Drawings.
6.10 Stop And Waste Valves:
All service lines shall have a stop and waste valve on the service line inside the residence near the location where the service line enters the residence. The stop and waste valve shall have a drain plug located on the valve body such that, when the valve is shut off, the drain plug can be removed and all water above the valve drained out. Stop and waste valves shall be approved by Denver Water. See Sheets 48 through 52 of the Standard Drawings for typical locations. Stop and waste valves shall conform to MS-21.
6.11 Control Of Backflow And Cross Connection:
A. Cross Connection Control:
1. Denver Water is responsible for the protection of its public water system from contamination or pollution due to the backflow of contaminants or pollutants through the water service connection. The purpose of this program is to:
a. Protect the public water supply of Denver Water from the possibility of contamination or pollution by containing within the customer’s internal distribution system(s) or the consumer’s private water system(s) such contaminants or pollutants which could backflow into Denver Water’s water system; and
b. Eliminate or control existing cross connections, actual or potential, between the consumer’s in-plant potable water system(s) and non-potable water system(s), plumbing fixtures and industrial piping systems; and
c. Provide for the maintenance of the Continuing Program of Cross Connection Control which will systematically and effectively prevent the contamination or pollution of potable water supplied by Denver Water.
B. Requirements for Backflow Prevention:
1. The water system will be considered as made up of two parts, Denver Water’s system and the consumer’s.
a. Denver Water’s system consists of the source facilities and the distribution system, and includes all those facilities of the water system under complete control of Denver Water up to the point where the consumer’s system begins.
b. The consumer’s system includes those parts of the facilities beyond the termination of Denver Water distribution system and are no longer under Denver Water’s control.
2. An approved backflow prevention device will also be installed on each service line within a consumer’s water system, immediately following the meter, and in all cases, before the first branch line leading off the service line wherever the following conditions exist:
a. In the case of a premise with an auxiliary water supply which is not or may not be of safe bacteriological or chemical quality and which is not acceptable as an additional source by Denver Water, Denver Water’s water system will be protected against backflow from the premises by installing an approved backflow prevention device in the service line appropriate to the degree of hazard found within the consumer’s premises.
b. In the case of premises on which any industrial fluids or any other objectionable substance is handled in such a fashion as to create an actual or potential hazard to Denver Water’s water system, Denver Water’s system will be protected against backflow from the premises by installing an approved backflow prevention device in the service line appropriate to the degree of hazard found within the consumer’s premises. This will include the handling of process waters originating from Denver Water’s system, which have been subject to deterioration in quality.
c. In the case of premises having internal cross connections that cannot be permanently corrected and controlled, or having intricate plumbing and piping arrangements or where entry to all portions of the premises is not readily accessible for inspection purposes, making it impractical or impossible to ascertain whether or not dangerous cross connections exist, Denver Water’s water system will be protected against backflow from the premises by installing a backflow prevention device in the service line.
d. In the case of premises where there is a fire protection system, an approved backflow prevention assembly must be installed on all water service connections. These would include such systems as residential, commercial industrial or institutional facilities serving any combination of fire hydrants, potable water and fire protection systems. The type of device required will depend upon the degree of hazard as determined by the Cross Connection Control Manual of the Colorado Department of Public Health and Environment.
3. The type of protective device required will depend upon the degree of hazard, as follows:
a. In the case of any premises where there is an auxiliary water supply, Denver Water’s water system must be protected by an approved air-gap separation or an approved reduced pressure principle backflow prevention assembly.
b. In the case of any premises where there is water or a substance that would be objectionable, but not hazardous to health, Denver Water’s water system must be protected by an approved double check valve assembly or an approved reduced pressure backflow prevention assembly.
c. In the case of any premises where there is any material dangerous to health, which is handled in such a fashion as to create an actual or potential hazard to Denver Water’s water system, Denver Water’s water system must be protected by an approved air-gap separation or an approved reduced pressure principle backflow prevention assembly. Examples of premises where these conditions exist include, but are not limited to, sewage treatment plants, sewage pumping stations, chemical manufacturing plants, hospitals, mortuaries and metal plating facilities.
d. In the case of any premises where there are uncontrolled connections, either actual or potential, Denver Water’s water system must be protected by an approved air-gap separation or an approved reduced pressure principle backflow prevention assembly at the service connection.
e. In the case of any premises where, because of security requirements or prohibitions or restrictions, it is impossible or impractical to make a complete in-plant cross connection survey, Denver Water’s water system must be protected against backflow from the premises by an approved air-gap separation or an approved reduced pressure principle backflow prevention assembly on each service line to the premises.
4. Any backflow prevention device required will be a model and size designated by Denver Water and approved by the Colorado Department of Public Health and Environment. The term approved backflow prevention assembly will mean a device that has been manufactured in full conformance with AWWA C511 and, have met completely the laboratory and field performance specifications of the Foundation for Cross Connection Control and Hydraulic Research (FCCC&HR) of the University of Southern California established by: Specifications of Backflow Prevention 69, current edition. AWWA and FCCC&HR standards and specifications are adopted by Denver Water. Final approval of backflow prevention devices will be evidenced by a Certificate of Approval issued by an approved testing laboratory certifying full compliance with said AWWA standards and FCCC&HR specifications. The following testing laboratory has been qualified by Denver Water and the Colorado Department of Public Health and Environment and accepted by Denver Water to test and certify backflow prevention devices:
Foundation for Cross Connection Control and Hydraulic Research
University of Southern California
University Park
Los Angeles, California 90007
5. It is the responsibility of the consumer at any premises where backflow prevention devices are installed to have certified inspections and operational tests made at least once per year. In those instances where the hazard is high enough, it may require inspections at more frequent intervals. These inspections and tests will be at the expense of the consumer and will be performed by a certified tester approved by Denver Water and/or the Colorado Department of Public Health and Environment. The consumer will notify Denver Water in advance when the tests are to be undertaken so that Denver Water’s representative may witness the test if so desired. These devices will be repaired, overhauled or replaced at the expense of the consumer whenever said devices are found to be defective. Records of such tests, repairs and overhaul will be kept by the consumer, and a copy of such records will be furnished to Denver Water.
6. Presently installed backflow prevention devices which do not meet the requirements of this section but were approved devices for the purposes described herein at the time of installation and which have been properly maintained, will, except for the inspection and maintenance requirements under subsection G., be excluded from the requirements of these rules so long as Denver Water is assured that they will satisfactorily protect Denver Water’s system. Whenever the existing device is moved from its present location or requires more than minimum maintenance or constitutes a hazard to health, the unit shall be replaced by an approved backflow prevention device meeting the requirements of Denver Water.
7. Denver Water shall review and approve the proposed backflow prevention device installation for all applications. Consultation with Denver Water Backflow Prevention Section may be required prior to plan submittal for special applications.
8. Backflow Prevention Assembly Installation Requirements:
a. Approved backflow prevention assemblies shall not be modified in any way after the device leaves the manufacturer’s factory.
b. Backflow prevention devices shall be located in a room maintained at a minimum of 40° F and with electric illumination.
c. Backflow prevention devices shall be installed where they are easily accessible for testing and maintenance.
d. Acceptable facilities sized in accordance with the Uniform Plumbing Code, such as floor drains, must be provided in the room in which the backflow prevention device is located to accommodate testing and maintenance procedures.
9. This Engineering Standard incorporates herein by reference the Cross Connection Control Manual of the Colorado Department of Public Health and Environment and the Colorado Primary Drinking Water Regulations of the Colorado Department of Public Health and Environment including all amendments made now or hereafter. Whenever there is a conflict between this Engineering Standard and the Colorado Cross Connection Control Manual, the most stringent standard will apply.
C. Identification of Hazards:
1. A clear understanding of cross-connection hazards is essential to the selection of appropriate backflow prevention measures. The applicability of an air-gap separation or of certain types of mechanical backflow prevention assemblies for resolution of a particular backflow condition depends upon the type of backflow and the degree of hazard. The degree of hazard is the actual or potential threat of contamination or pollution resulting from a cross-connection. A contamination hazard is an actual or potential threat of contamination, of a biological, physical or toxic nature, to Denver Water’s system or the consumer’s potable water system to a degree, which creates a hazard to public health. A potential hazard is an actual or potential threat of pollution to Denver Water’s system, or the consumer’s potable water system, which does not create a hazard to public health.
2. Based on national experience, premises where existing or potential contamination hazards present an imminent and substantial endangerment to public health must always be separated from public potable water systems by cross-connection control by containment. Similarly, existing or potential contamination hazards that present an imminent and substantial endangerment to public health within a consumer’s premise, must always be separated from the consumer’s potable water system by cross-connection control by isolation.
3. Those premises for which separation from Denver Water’s system by containment is mandatory, are included in the list that follows:
a. Unapproved auxiliary water supplies on premises, including private wells
b. Premises where access is limited or restricted because of security concerns
c. Hospitals, morgues, mortuaries, medical clinics, dental clinics, and autopsy facilities
d. Laboratories
e. Sewage treatment plants or facilities
f. Food and beverage processing plants
g. Chemical plants
h. Metal plating industries
i. Electrical and electronic component manufacturers
j. Radioactive material processing plants
k. Car and truck wash facilities
l. Hydraulic testing facilities
m. Packing houses, rendering plants, tanneries, and stock yard facilities
n. Steam generating facilities
o. Laundries, dry cleaners, laundromats
p. Photographic film processing facilities
q. Swimming pools and health spas
r. Greenhouses
s. Multi-storied buildings in excess of 30 feet above finished grade
t. Fire protection systems
u. Landscape irrigation systems
v. Taxidermy shops
w. Battery shops
x. Kennels, pet shops
y. Solar installations
z. Printing shops, screen printing shops
aa. Jewelry manufacturers
bb. Radiator shops
cc. Water service connections to commercial, industrial and institutional facilities
D. Special Applications:
1. Fire Protection Systems.
a. An approved backflow prevention assembly shall be installed on any private fire protection system because of the following concerns:
1) The growth of offensive microorganisms, which can create taste and odor problems.
2) The leaching of heavy metals such as zinc, cadmium, iron, or lead into water which stands in pipelines for long periods of time.
3) The addition of corrosion inhibitors or antifreeze compounds to protect the piping systems.
4) Dry air systems containing compressed air.
5) A loss of pressure on the public water supply main or an increase in pressure on the consumer’s system which would allow water from these systems to flow backward into Denver Water’s system.
b. These hazards will vary from a non-health hazard to a health hazard. For this reason, it is required that all private fire systems must be protected from backflow. The protection will be commensurate with the degree of hazard. Listed below are those situations which determine the different fire system hazards, and the type of protection required for each:
1) Low or Moderate Hazard Fire Systems:
(a) Wet or dry with pumper connection.
(b) Wet system with an in-line booster pump.
(c) Any system with private hydrants
(d) Any looped system (an inter-tied system with more than one service connection).
2) High or Severe Hazard Fire Systems:
(a) Systems with pumper connections where corrosion inhibitors or other chemicals are added to the tanks of fire trucks.
(b) All foamite plant installation.
(c) Systems where an unapproved water supply can be connected to a fire system.
(d) Systems in which antifreeze is allowed.
c. Backflow Protection Required:
1) Low or Moderate Hazard Fire Systems require an approved Double Check Valve Assembly.
2) High or Severe Hazard Fire Systems require an approved Reduced Pressure Principle Backflow Assembly.
d. Installation of backflow prevention assemblies on systems involving fire pumps shall have a low suction pressure shutdown provided with a minimum operating pressure of 10 psi.
e. When retrofitting an existing fire protection system, prior to installing a backflow prevention device, the design and the installation must be reviewed and approved by a licensed by the State of Colorado Professional Engineer experienced in fire protection. This review will involve an analysis of the existing fire protection system to ensure that the addition of the backflow prevention device will not adversely affect the fire protection system’s performance.
f. When retrofitting an existing fire protection system, work shall be performed by a contractor registered with the State of Colorado, and where applicable, with the local fire protection authority, to work on fire protection systems.
g. In all cases, the water supplier is the final approval authority for installation of backflow prevention devices on fire protection systems.
2. Irrigation Systems
a. An approved backflow prevention assembly shall be installed on all water service connections that are used exclusively for landscape irrigation, and an approved backflow prevention assembly must be installed as an isolation device on residential, commercial, industrial, instit-utional, and public facilities that use the public water supply for lawn or landscape irrigation. Because landscape irrigation systems are subject to cross connections due to flooding, agricultural chemicals such as fertilizers, pesticides, fungicides, soil conditioners, and from submerged outlets, auxiliary water supplies, ponds, reservoirs, swimming pools, and other sources of stagnant, polluted or contaminated water, these systems are considered to be actual or potential high or severe hazard situations.
1) Backflow protection in the form of approved atmospheric and pressure vacuum breakers are approved for use in landscape irrigation system, with the following exceptions:
(a) Locations subject to flooding
(b) Systems which are subject to back pressure conditions
(c) Systems winterized by injection of compressed air
(d) Systems which inject fertilizers or other chemicals
2) With the exception of landscape irrigation systems, pressure vacuum breakers are not approved for cross connection control by containment. Atmospheric vacuum breakers are not approved for cross connection control by containment or whenever there is a control valve located downstream of the device.
3) Air gap separations or reduced pressure principle backflow assemblies are required for irrigation systems subject to the following conditions:
(a) Locations subject to flooding
(b) Systems subject to back pressure conditions
(c) Systems winterized by injection of compressed air
(d) Systems which inject fertilizers or other chemicals
(e) Premises that have auxiliary water sources available for irrigation
4) Double check valves are not approved for landscape irrigation systems.
3. Solar Heating Systems
a. An approved backflow prevention assembly must be installed on the water service line, as protection from cross connections, at any premise having a solar heating and/or cooling system that is connected to the consumer’s water system, with the exception of a single-family residential premise, which must install an approved backflow prevention assembly as isolation protection from cross connections. The hazards normally found in solar heating and/or cooling systems include cross connections between the consumer’s water system and:
1) Reservoirs and storage tanks
2) Solar collector fluids which may contain:
(a) Antifreeze compounds
(b) Toxic corrosion inhibitors
(c) Non-potable water
(d) Single wall heat exchangers between consumer’s potable water and the collector fluids
(e) Negative pressure zones created by circulation pumps
3) Some solar water heating systems rely on non-toxic antifreeze solutions and/or non-toxic corrosion inhibitors. However, Denver Water has no assurance that these systems will not be subsequently altered to utilize a toxic fluid; therefore, the required protection shall be an approved reduced pressure principle backflow prevention assembly. It is to be used either as a containment device or as an isolation device.
6.12 Valve Boxes:
All buried gate valves 12 inches and smaller shall be provided with a 6 inch cast iron valve box, and large oval base. The valve box shall be of a design, which will not transmit shock or stress to the valve and shall have enough extension capability to be raised to final street grade. Valve boxes shall conform to MS-11. The top section of the valve box shall be acceptable for use with a butterfly valve as shown on Sheet 18 of the Standard Drawings.
6.13 Valve Reference Marker Posts:
When valves are installed where adequate physical reference points are not available, a valve reference marker post shall be required. Reference marker posts shall conform to Sheet 33 of the Standard Drawings.
6.14 Meters:
Meters installed for billing purposes shall be under the control of Denver Water. No meter shall be installed until the proposed installation has been approved, and the meter tested and numbered by Denver Water.
Meters used to record usage by the retail consumer are called service meters. Meters used by wholesale customers and which supply water to other service meters are known as master meters. Other temporary meters may exist in the system for the purpose of Denver Water tests.
The characteristics which are of special importance in meters are accuracy and sensitivity, durability, low pressure loss, cost at purchase and installation, ease and low cost of maintenance, and compatibility with Denver Water’s radio-frequency automatic meter reading system, using Itron ERT’s (encoder-receiver-transmitter units). Registers and the associated Itron ERTs must be programmable using a standard ROCL program. Registers and ERTs using a WYSIWYG ROCL program are not acceptable. Pit ERTs shall be used for most pit installations of 5/8 inch, 3/4 inch and one inch meters and for some vault installations of larger meters. Remote ERTs shall be used for indoor meter installations and for some outdoor installations where there may be difficulty obtaining a drive-by reading from a public street.
Meter installations shall be inspected by Denver Water upon completion of the installation, prior to backfilling. Installations which do not comply with these Engineering Standards shall be made to conform prior to acceptance by Denver Water.
6.15 Size Of Meter:
Meters shall be of the same size as the corporation stop and that portion of the service pipe between the meter and the corporation stop. In no case shall a meter smaller than 3/4 inch be installed, except as a replacement for an existing smaller meter.
Denver Water may allow the installation of a meter of a size smaller than the service pipe in cases where the full capacity of a previously used service pipe is not required, provided that the service pipe is reduced to the size of the meter for a distance of not less than 10 times the larger pipe diameter on the inlet (supply) side of the meter or five feet, whichever is longer.
6.16 Type Of Meter:
The type of meter installed will be determined by Denver Water at the time of application based upon size, service requirements, location of meter and other conditions, which may exist.
6.17 Magnetic Drive Displacement Meters:
The displacement meters, known as nutating-disc or oscillating piston meters, are positive in action in that the pistons and discs displace or carry over a fixed quantity of water for each nutation or oscillation when operated under positive pressure. The magnetic drive displacement type water meter shall be furnished with a cast-iron "frost bottom" (also referred to as "frost-proof").
Meter sizes l-l/2 inch and larger shall be brass, 2-hole, oval flange construction. Companion flanges shall be brass.
6.18 Compound And Turbine Meters:
Compound meters consist of two meters in a single case, one to measure small flows and the other to measure large flows. Some fireline meters are made with the two meters in separate cases coupled together as an integral unit Compound meters are so designed that the small meter operates during low flows and as flows begin to increase, the large meter takes over. When the large meter is in operation the small meter may or may not be in operation.
Turbine meters are designed to measure primarily large flows, and should not be used where the possibility of small flows below the manufacturer's stated minimum flow exists.
All turbine meters size 3 inch and larger shall have a flanged in-line basket strainer installed on the upstream side. All turbine meters smaller than size 3 inch shall include an integral stainless steel strainer with removable top plate as described in MS 17-A.
In general, meters sizes 3 inches and larger for use as master meters, or in commercial, industrial, manufacturing, or irrigation uses, shall be turbine type meters conforming to MS-17. Meters sizes 3 inches and larger, for uses other than those described for turbine meters, shall be compound type meters conforming to MS-16.
In addition to the usage guidelines stated above, the provisions of 6.16 shall apply to the compound and turbine meters.
Compact fireline meters, a specialized type of compound meter, shall be used on any service which includes fire sprinklers, fire hydrants, or other fire protection behind the meter, and in such other cases as may be determined by Denver Water. Fireline meters are required to meet specialized standards of Underwriters Laboratories and other certifying agencies.
Each register of each meter shall be furnished with an electronic encoder register and an Itron ERT. Devices designed to electronically combine the readings of multiple registers into a single ERT shall not be permitted. ERTs shall be mounted as directed by Denver Water Customer Service Field Section.
6.19 Outside Meter Settings:
All outside meters shall be installed in a horizontal position and housed in a concrete manhole or vault, and shall conform to Sheets 47, 48, 49, 50, 55, 56, 60, 61, 62, 63, 73, and 74 of the Standard Drawings.
Each Water meter dial shall be equipped with an Itron ERT, mounted in accordance with Denver Water’s standards. In most cases, the meter will be equipped with a pit ERT mounted through the meter pit/vault lid. In special circumstances, identified by the Customer Service Field Section, a remote ERT may be required at a distance of up to 250 feet from the meter pit or vault, mounted on the building or another structure. Signal wire for remote ERT installations shall be run through conduit.
6.20 Inside Meter Setting And Remote Readers:
Inside meter settings shall be installed in a manner which will allow free access and adequate room for inspection and maintenance and will protect the meter from freezing. Meter sizes 3/4 inch and one inch installed inside of buildings shall be located in a basement area, approximately 40 inches above the floor level, and not more than 18 inches from the wall through which the service pipe enters the building. See Sheet 51 and 52 of the Standard Drawings. Meter sizes 1-1/2 inch and 2 inch installed inside buildings shall comply with Sheet 53 of the Standard Drawings.
Inside meter settings shall not be allowed in crawl spaces, closets or other places where free and easy access is not provided. Meter sizes 1-1/2 inch and 2 inch installed inside buildings shall be equipped with a floor drain.
If the property owner proposed to enclose the meter or place it behind a wall, a suitable door or access panel shall be provided in conformance with Sheet 52 of the Standard Drawings.
In buildings without basements, the water meter shall be installed indoors only under the following conditions:
A. The meter shall be installed in a heated utility room with a floor drain, and may not be installed in any space intended for continuous human occupancy.
B. The service line shall not exceed 60 feet in length, measured along the center line of the service pipe from the corporation stop to the inlet to the meter.
C. The meter shall be set in a location that will permit an acceptable remote ERT installation within 100 feet of the meter setting. The ERT shall be mounted on the inside or the outside of the front wall of the building.
Each water meter dial shall be equipped with an Itron remote ERT with 20-foot signal cable, mounted to maximize radio signal penetration. If the ERT signal cable length will exceed 20 feet, or if the wire is to be concealed behind a finished wall, the owner shall provide approved cable from the meter location to the ERT location, leaving enough extra cable at each end to make the spliced connections to the meter and the ERT.
6.21 Meter Bypass Lines:
A bypass line shall be required for all meters 1-1/2 inch and larger, except for meters intended solely to supply irrigation systems, unless otherwise specified by Denver Water, whether installed in an outside or inside setting. Bypass lines shall contain an independent control valve and shall contain no tees, plugs, or other outlets through which water could be withdrawn. Bypass lines permit the consumer to have water while their meter is being repaired or replaced. Bypass lines must be locked in the off position at all other times. Only a Denver Water employee is authorized to unlock and turn on a bypass line. Bypasses are not permitted on irrigation service lines.
6.22 Meter Check Valves:
Check valves will be required for all meters 1-1/2 inch and larger unless otherwise specified by Denver Water, whether installed in an inside or outside setting. Check valves may be required on meters smaller than 1-1/2 inch where any condition might exist that could cause a flow of water from the property to the main. Also see 6.09. Check valves are not required when a backflow prevention device is installed on the service line downstream of the meter.
6.23 Valves For Use With Meters:
Type of valve for size 2 inches and smaller shall depend on the size and type of setting as follows:
A. For inside and outside meter settings for a 1-1/2 inch or 2 inch meters, as shown on Sheet 55 and 56 of the Standard Drawings curb stop valves are required.
B. For an inside meter setting for a 3/4 inch or one inch meter, as shown on Sheets 49, 50 & 51 of the Standard Drawings, a stop-and-waste valve shall be installed on the supply side of the meter and a gate valve shall be installed downstream (on the building side) of the meter.
C. For an outside meter setting for a 5/8 inch x 3/4 inch, 3/4 inch or one inch meter, as shown on Sheets 48 and 49 of the Standard Drawings, an angle valve is required in the meter pit as part of the meter setting. (Note: 5/8 inch x 3/4 inch meters may only be used to replace existing meters of the same size; if the meter setting is changed, it must be upgraded to a 3/4 inch setting and meter.)
All valves shall be in accordance with MS-21.
Valves 3 inches and larger for use with cast or ductile iron service pipe shall be gate valves conforming to MS-4, or resilient seated gate valves in accordance with MS-4A, except they shall have mechanical joints on both ends. All gate valves larger than 3 inches for use with meters shall be supported by adjustable steel valve supports. This support shall conform to Sheet 39 of the Standard Drawings.
See also 3.10.
6.24 Meter Couplings:
Meters 3 inches and larger shall be installed with a coupling to allow removal of the meter without disturbing the pipe. Couplings shall conform to MS-22.
6.25 Meter Yokes (Line Setters):
A yoke is a metal pipe frame attached to the inlet and outlet sides of the meter providing support, and conveying water to the meter. Meter yokes shall conform to MS-21.
To assure safety, the water meter setting shall provide a continuous, electrically conductive, path around the water meter. If a bonding jumper is required, it shall be made of copper with fittings suitable for the bonding jumper and the water pipe material. The meter setting installation shall be in compliance with the NEC.
6.26 Valve And Meter Supports:
Meter supports shall be a solid concrete block as shown on Sheets 55, 56, 69, 60, and 62 of the Standard Drawings. Fabricated metal supports shall be used to support valves 3 inches and larger and shall conform to Sheets 59, 60, 62, 74, and 76 of the Standard Drawings.
6.27 Meter Pits And Covers For 3/4 inch And One inch Meters:
Meter pits shall consist of four 12 inch pre-cast concrete rings or any combination of pre-cast concrete rings that total 48 inches in height. The rings shall have a 2 inch minimum wall thickness. The rings shall be constructed of concrete in accordance with MS-18 and comply with all requirements of ASTM C 478. Plastic meter pits are not permitted. An aluminum dome or bell housing shall be mounted on the top of the pit; the dome or bell housing shall have a support for an interior frost lid and a rim for locking the meter pit cover. The meter pit cover shall have a cast iron, cap type, top lid, with a recess to hold the Itron ERT. There shall be a 2 inch diameter hole to accommodate the ERT, and not less than three drainage holes within the recessed area to prevent the buildup of water and ice. An alternative meter pit cover is one made of polymer-concrete composite material with integral supports for the Itron Pit ERT. All meter pit covers shall have a locking screw and bolt that provides a tight locking of the cover to the dome or bell housing of the meter pit. See Sheet 49 of the Standard Drawings and MS-23. The inner frost lid shall be high density polyethylene. The frost lid shall be dish shaped, with a 3 inch depth, and shall have three to five drainage holes and an integral lifting handle. See Sheet 49 of the Standard Drawings and MS-23.
6.28 Vaults:
Vaults may be pre-cast or cast-in-place. Pre-cast vaults shall be so designed that all joints and corners are waterproof. The roof and walls of pre-cast and cast-in-place vaults shall be made waterproof after construction by use of sealants, epoxies or other approved methods.
If the vault is not to be in a street, the roof shall be designed to support the overhead earth fill and any other reasonable loading that may occur. If the vault is to be built in a street, the roof shall be designed to support the street fill and HS-20 traffic loading in accordance with AASHTO Standards. However, if there is any doubt, the vault shall be designed for the traffic loading. Particular care shall be taken in selecting pre-cast vaults that the application not be one of either shallow or deep cover over the roof. Should the cover over the roof be less than 2-1/2 feet or more than 5 feet, concern for adequacy of the roof, or the ability to remove and replace a one piece roof slab resting upon deflecting side walls may dictate a cast-in-place vault.
Automatic meter reading ERTs shall be mounted inside the vault, in a remote location on the side of a building or on a pole, or through the access cover to maximize radio signal penetration.
Cast-in-place meter vaults shall conform to Sheets 60 through 63 and 74 through 77 of the Standard Drawings. See MS-18, MS-19, MS-21 and MS-26.
6.29 Concrete Structures:
Structures shall be designed to support applicable loads. Design calculations, drawings, and contract specifications shall be submitted to Denver Water for review.
Concrete used in structures shall be Class "A". See MS-18, and 8.21.
6.30 Steel Reinforcement For Concrete:
Steel reinforcement shall be either deformed bars or welded steel fabric and shall conform to MS-20.
6.31 Manholes:
Manholes, reducing sections, ladder rungs, and traffic lids shall be pre-cast concrete and conform to ASTM C 478 and MS-18. All traffic lids shall be designed for HS-20 traffic loading in accordance with AASHTO Standards. All ladder rungs or manhole steps shall be cast into the manhole barrel when the manhole barrel is cast.
Concentric reducing sections shall not be used. The top of the manhole vault shall be a minimum of 12 inches and a maximum of 18 from the official street or ground surface elevation. Concrete extension collars shall be used to bring the manhole ring and cover up to official street or ground surface elevation. These grade rings shall be constructed of concrete in accordance with MS-18, and shall comply with the requirements of ASTM C 478.
Manhole rings and covers:
A. Twenty-four inch manhole rings and covers shall be "City of Denver, Colorado Standard" pattern. Twenty-four inch cover weighs approximately 165 pounds. Twenty-four inch ring weighs approximately 240 pounds.
B. Twenty-four inch x 36 inch double ring and cover: The 36 inch cover shall have an auxiliary 24 inch opening and cover. Thirty-six inch cover weighs approximately 250 pounds. Thirty-six inch ring weighs approximately 280 pounds.
6.32 Manhole Base Slabs And Base Beams:
Manhole base beams shall be pre-cast, reinforced concrete. The beams shall be 12 inches wide by 9 inches deep by 8 feet long. The reinforcement shall consist of three No. 5 bars, evenly spaced, and No. 4 bars at 12 inch centers transversely.
Manhole base slabs may be cast-in-place or pre-cast. The slab shall be designed to uniformly support the earth load and any other reasonable loads that may occur. The minimum slab thickness shall be 6 inches. The minimum reinforcement shall be welded wire fabric, 4 x 4 - W4 x W4. Splicing of the welded wire fabric shall be by lapping one space and securing the wire mesh together. The concrete shall conform to MS-18 and the reinforcement shall conform to MS-20.
6.33 Sump Pits For Vaults And Manholes:
Sumps are required for vaults or manholes in areas where there is seepage into existing vaults and in all pressure regulating valve installations.
A gravity drain line or sump pump shall be used in conjunction with a sump where telemetry equipment is to be installed. See Sheets 43 and 45 of the Standard Drawings.
Normal practice in constructing a sump is to excavate a 30 inch diameter hole about 3 feet deep. A 6 inch floor is placed and allowed to set. Then a 24 inch section of cardboard tubing is used for an inside form, and concrete is poured behind it approximately 3 inches thick. See Sheets 43 and 44 of the Standard Drawings showing a sump as part of a typical pressure regulating valve installation.
6.34 Vent Pipes:
Vent pipes are used in vaults and pits to provide proper ventilation. Installations that contain electrical equipment shall have a locally controlled, power operated blower attached to the vent system. Vent pipes shall be field located at the nearest intersection of the street property line and the side lot line. See Sheets 40 through 42 of the Standard Drawings for vent pipe installation details. A residential vent pipe assembly as shown in Sheet 40 may be used where an inconspicuous installation is desirable.
Above ground vent pipe shall be 6 inch nominal diameter galvanized steel pipe, conforming to ASTM A 53. The vent screen shall be a 3/4 inch No. 9-11 flattened expanded galvanized metal screen. See Sheet 41 of the Standard Drawings. Below ground vent pipe shall be 6 inch, schedule 40 PVC with glued joints. A PVC glued joint by standard pipe thread female adapter shall be used to connect the steel pipe to the PVC pipe at ground level. Where the residential vent pipe assembly is used this adapter is not needed. PVC pipe is not allowed with 8 foot above ground risers.
6.35 Manufacturer And Model Of Fire Hydrants:
Within the City and County of Denver and Total Service Areas, where maintenance, repair, replacement, and parts stocking is the responsibility of Denver Water, only the four manufacturer's brands of hydrants listed in MS-12, are acceptable.
In Distributor Contract Areas, fire hydrants conforming to MS-12, but without limitation to the brand names chosen by Denver Water for their own use, shall be used. Any brand and model used, however, must have prior Denver Water approval. Two such brands which have met approval are listed in MS-12.
6.36 Fireline Connections To Mains:
Firelines supplying sprinklers shall be sized by the appropriate fire protection bureau and the persons responsible for the structure it protects. Denver Water will not size firelines.
The fireline shall be restrained ductile iron pipe. A fireline shall have a valve 2 feet from the property line on the street side of the property line as shown on Sheet 35 and 36 of the Standard Drawings.
6.37 Service Lines:
Service lines shall be sized to adequately supply the requirements of the property being served. The minimum size line shall be 3/4 inch. The only acceptable material for a service line is seamless copper tube, Type K (soft) for sizes through 3 inch and ductile iron pipe for sizes 3 inches and larger. Service lines shall be of the same type material from beginning to end, unless the appropriate insulator is installed at the junctions of the dissimilar metals. See 3.09, MS-1 and Sheets 48 and 50 of the Standard Drawings. Unless otherwise approved by the Customer Service Field Section, there shall be no bends or changes in the size of the service line between the tap and a point five feet past the meter pit or vault for outdoor meter settings, or between the tap and a point five feet past the curb stop for indoor meter settings.
6.38 Corporation Stops:
Corporation stops provide the connection for the service line to the main. By utilizing a corporation stop, a service can be connected to the main without taking the main out of service. Corporation stops are also used in air and vacuum valve and large butterfly valve installations as shown in Sheets l6 through l8 of the Standard Drawings. Corporation stops are made in standard sizes 3/4, one inch, 1-1/2 inch, and 2 inch. See Chapter 3, MS-21 and Sheets 48 and 50 of the Standard Drawings.
6.39 Curb Stops:
Curb stops are set on the service line near the property line and provide a means to shut off the service line. For outside meter settings, the curb stop must be placed from two to five feet from the inlet side of the meter pit. Placement of the curb stop and stop box may vary from a maximum of 5 feet outside the property line (in the street or easement) to a maximum of 5 feet inside the property line (on the customer’s property). Placement of the curb stop and stop box outside the property line is preferred. Curb stops and boxes will be located in landscaped areas unless otherwise approved by the Customer Service Field Section. Where the curb stop must be placed beneath a roadway, street or parking lot, it shall be located where vehicles can not park over it. See Sheets 48 and 50 of the Standard Drawings and MS-21 for further details.
6.40 Curb Stop Service Boxes:
Curb stop service boxes shall be cast iron, Buffalo type. The bottom part shaped like an inverted U straddling the service line shall have a flanged bottom so as to support itself. Curb stop service boxes shall conform to MS-22.
6.41 Corrosion Protection Systems:
Metallic pipe and fittings shall be protected against corrosion.
A. Polyethylene Encasement Material: Polyethylene wrap shall be used on all cast iron or ductile iron pipe, fittings, rods, and appurtenances where the soil resistivity is greater than 1,000 ohm-centimeters. Polyethylene material shall conform to MS-13 and Sheet 38 of the Standard Drawings.
Twenty-four inch flat width tubing shall be used with 4 inch, 6 inch, and 8 inch pipe. Thirty inch flat width tubing shall be used with all 12 inch pipe. Thirty-six inch flat width tubing shall be used for 16 inch pipe. Fifty-two inch flat width tubing shall be used with 20 inch and 24 inch pipe.
Harness rods shall be covered by 4 inch flat width polyethylene tubing. The entire joint shall be covered by a cigarette-wrap of 48 inch wide polyethylene sheet material over each set of lugs. Irregular shaped valves and fittings shall be covered with flat 48 inch wide polyethylene sheet material.
B. Insulators: Insulators shall be installed at the outlet end of the corporation stop as shown on Sheets 48 and 50 of the Standard Drawings. Insulators shall be in accordance with MS-22. See Sheet 37 of the Standard Drawings and MS-22 for other insulators, which may be required.
6.42 Kickblocks:
Concrete kickblocks shall be sized for the working pressure plus water hammer surge pressures as stated in 6.03 and the soil bearing capacity. Standard shapes and sizes of kickblocks are shown on Sheets 19 and 20 of the Standard Drawings.
The kickblocks shall be of Class B concrete conforming to MS-18, or of a pre-measured, sacked industrial mix such as Sakcrete, Dri-mix, or an approved equal. Ready-mixed concrete mixes shall be approved by Denver Water.
6.43 Protective Concrete Pads Over Pipe:
Under unusual circumstances it may be necessary to lay pipe at shallow depths. Concrete pads shall be used over the pipe to protect it from the traffic loading. The pads shall be designed to support loads from traffic without transmitting the load, to the pipe. Approved Insulation as approved by Denver Water shall be required between the pipe and the concrete pad to protect the pipe from frost. This situation, and its solution, shall be subject to approval by Denver Water.
6.44 Casing Pipe:
Installation of mains through Denver Water rights-of-way or rights-of-way or easements of others, such as highways, railroads, etc., may require casing pipes to facilitate the installation of the main. The type of casing material and its properties will be specified by the agency granting permission to cross. Such crossing shall be subject to approval by Denver Water to avoid conflicts in requirements or standards between Denver Water and the persons or agency granting permission to cross.
See Sheets 28 and 29, of the Standard Drawings for details. Final approval of the boring and casing methods and materials shall be obtained from Denver Water prior to construction. Where a bore is not required to cross interference, Denver Water may require the installation of the main under the interference in conformance with Sheet 28 and 29 of the Standard Drawings.
6.45 Miscellaneous Metalwork And Piping:
All fabrication shall be equal to the best practice in modern fabricating shops. Welding shall be performed by certified welders, with all exposed welds ground smooth. All weld splatter shall be properly removed to the satisfaction of Denver Water.
All exposed hardware, including nuts, washers, bolts and anchor bolts, shall be galvanized.
All exposed metal that is to be buried shall be given two coats of CA-1200 mastic cold coating as manufactured by Protecto Wrap Company, Denver, Colorado, or equal, except for metal with shop applied coating approved by Denver Water.
All metal exposed to weather shall be painted with one coat of a rust inhibiting priming paint and two coats of aluminum paint, unless otherwise directed by Denver Water. Surfaces to be painted shall be cleaned of oil, grease, weld spatters, burrs, grit, dust or other objectionable surface irregularities. Cleaning solvent used shall be mineral spirits. Copper, aluminum or galvanized pipe need not be painted, unless so directed by Denver Water.
All miscellaneous piping shall be installed in the best workmanlike manner. All threads on steel pipes shall be cut with sharp dies to standard depth, left clean cut, and tapered. Threaded pipe joints shall be properly sealed with an approved joint compound applied on the male threads only.
All concealed joints for copper water tubing within buildings shall be soldered or brazed in conformance with the appropriate building code. The joint of the copper pipe shall be properly cleaned, flux applied, and soldered with 95-5 tin-antimony solder, all applied in accordance with the best plumbing practice. All parts to be soldered shall be thoroughly cleaned before flux is applied. All copper piping, where the pipe is in direct contact with pipe hangers or other metal supports, shall be protected with a copper saddle soldered to the underside of the pipe. Saddles may be made of split copper pipe.
All copper joints installed underground shall be flared or brazed. Flaring and brazing shall be performed with the best plumbing practices.
6.46 Air And Vacuum Release Valves:
Combination air release and vacuum relief valves shall be required for Conduits and may be required for transmission mains at the discretion of Denver Water. Air release and vacuum valve assemblies as shown on Sheet l6 and 17 of the Standard Drawings shall be installed at high points in the Conduit, where there is an abrupt change of slope and at line valves where the Conduit slopes away from the valve or as determined by Denver Water. See MS-10.
Engineering Standards - Chapter 6:
Revised 07-04, Previous Revision 05-02
End