For use in the Denver Water Service Area |
The Board Of Water Commissioners
Denver Water
Engineering Standards
Chapter 8 – Pipe Installation
8.01 Approval By Denver Water:
Many handling and installation procedures, tools, equipment, and materials require approval by Denver Water. Approval by Denver Water shall in no manner render Denver Water liable for any injuries suffered or equipment damaged. Approval by Denver Water is used solely as a means to insure quality control.
Safety of workers shall be provided as required by OSHA.
8.02 Handling Of Materials:
Pipe and fittings shall be loaded and unloaded by lifting so as to avoid shock or damage. Under no circumstances shall such material be dropped. If, however, any part of the coating or lining is damaged, the replacement or repair of the damaged pipe shall be done to the satisfaction of Denver Water. Any pipe or fittings that are not acceptable to Denver Water shall be removed from the job site immediately. Pipe handling equipment and pipe handling methods shall be approved by Denver Water.
8.03 Preparation And Inspection Of Pipe And Fittings For Installation:
Before placing pipe in the trench, each pipe or fitting shall be thoroughly cleaned of all foreign material, kept clean at all times thereafter, and carefully examined for cracks and other defects before installation. Bell ends and spigot ends are to be examined with particular care.
8.04 Pipe Joint Lubricant:
Joint lubricant shall be as supplied by the pipe manufacturer, and approved by Denver Water. Joint lubricant shall be non-toxic, water soluble, and certified to meet NSF Standard 61.
8.05 Cutting And Fitting Of Pipe:
Pipe shall be cut, whenever necessary, to conform to location of fittings, line, or grade. All cuts shall be straight and true, in a workmanlike manner so as to leave a smooth end without damaging the pipe. All burrs shall be removed from the ends of cut pipe, and the end lightly rasped or filed. All tools used in cutting pipe shall be approved by Denver Water.
| Power-driven saws with abrasive discs (masonry blades) shall not be used for dry cutting or beveling asbestos-cement pipe. In recognition of efforts to reduce the incidence and corresponding danger of airborne asbestos fibers, MOA PVC pipe may be used in place of MOA asbestos-cement pipe wherever cutting is necessary. |
8.06 Pipe Alignment And Grade:
In laying pipe, the intent is to lay to set line and grade within a tolerance of 3 inches plus or minus. On slopes of zero grade, the intent is to lay to grade. Fittings, valves, and hydrants shall be installed at specified locations and elevations.
When laying pipe on curves, the intent is to lay to the alignment. The pipe shall be kept in alignment by placing the joints or bends on the curve. Short lengths shall be used as necessary to accomplish the curvature without exceeding individual deflections specified by the pipe manufacturer. Bends shall be used whenever individual deflections exceed those specified by the manufacturer.
For all pipes the depth of cover over the pipe measured from official street grade to the top of the pipe shall be a minimum of 4-1/2 feet and shall be known as the cover over the pipe. If difficulties arise when crossing interference and where specifically approved by Denver Water, deviations from 4-1/2 feet of cover will be permitted. Cover over the pipe shall be a minimum of 3 feet and a maximum of 10 feet.
Any changes in alignment and grade shall be authorized by Denver Water and shall be accomplished by the installation of additional fittings. Breaking of joints is permitted only when installing pipe on horizontal or vertical curves.
Pipe shall be laid with bell ends facing the direction of laying, unless directed otherwise by Denver Water.
8.07 Deviation From Alignment And Grade Occasioned By Other Structures:
Whenever obstructions not shown on the plans interfere to such an extent that an alteration in the plans is required, Denver Water shall have the authority to determine the best method of correction. Denver Water's Inspector may change the plans and order a deviation from line and grade, or arrangements may be made with the owners of the structure for its removal, relocation, or reconstruction.
8.08 Temporary Bulkheads:
Whenever the pipe is left unattended, temporary plugs shall be installed at all openings. Temporary plugs shall be watertight and of such design as to prevent children and animals from entering the pipe. All temporary plugs shall be approved by Denver Water.
8.09 Frost:
No pipe or appurtenant structure shall be installed upon a foundation into which frost has penetrated, or at any time when Denver Water deems there is danger of ice formation, or frost penetration at the bottom of the excavation. No pipe or appurtenant structure shall be installed unless backfilling can be completed before the formation of ice and frost.
8.10 Ductile Iron Pipe:
A. Push-on Joint: Immediately before joining two lengths of ductile iron pipe, the inside of the bell, the outside of the spigot end, and the rubber gasket shall be thoroughly cleaned to remove oil, grit, excess coating, and other foreign matter. The rubber gasket shall be flexed inward and inserted in the gasket recess of the bell socket. Caution shall be exercised to ensure the correct type of gasket is used.
A thin film of joint lubricant shall be applied to either the inside face of the gasket, or the spigot end of the pipe, or both.
The spigot end of the pipe shall be placed in the bell end with care to prevent the joint from contacting the ground. The joint shall be completed with a slow, steady pressure without jerky or jolting movements. Pipe furnished without a depth mark shall be marked before assembly to assure insertion to full depth of the joint. The spigot end of field cut pipe lengths shall be filed, or ground to resemble the spigot end of such pipe as manufactured.
B. Mechanical Joint: Before joining mechanical joint cast iron fittings to ductile iron pipe, the outside of the spigot, the inside of the bell, and the rubber gasket shall be thoroughly cleaned to remove oil, grit, excess coating, and other foreign matter.
Normal practice is to lubricate the joint with a soap solution; however, in cold weather the joint may be assembled dry if approved by Denver Water. Extreme care shall be exercised in making dry joints.
The gland shall be slipped on the spigot end of the pipe with the lip extension of the gland toward the socket, or bell end. The rubber gasket shall be placed on the spigot end with the thick edge toward the gland.
The pipe shall be pushed in until the spigot end fully penetrates the bell. The gasket shall then be pressed into place within the bell evenly around the entire joint. The cast iron gland shall be moved along the pipe into position for bolting; the bolts inserted, and the nuts screwed finger tight, then tightened with a torque limiting wrench. Torques for the various sizes of bolts shall be as follows:
| Pipe Size (inches) | Bolt Size (inches) | Range of Torque (foot-pounds) |
|---|---|---|
| 3 | 5/8 | 45-60 |
| 4-24 | 3/4 | 75-90 |
| 30-36 | 1 | 100-120 |
| 42 | 1-1/4 | 120-150 |
Nuts spaced 180 degrees apart shall be tightened alternately in order to produce equal pressure on all parts of the gland.
All mechanical joint fittings shall be wrapped with polyethylene encasement material in accordance with 6.41 A.
C. Bolted Sleeve Type Couplings: When installing bolted sleeve type couplings, care shall be taken that the connecting pipe ends, couplings, and gaskets are clean and free of all dirt and foreign matter with special attention given to the contact surfaces of the pipe, gaskets, and couplings. These couplings shall be assembled and installed in conformity with the recommendation and instructions of the coupling manufacturer.
Bolted sleeve type couplings shall be wrapped with polyethylene encasement material in accordance with 6.41 A.
Wrenches used in bolting couplings shall be of a type and size recommended by the coupling manufacturer. Coupling bolts shall be tightened so as to secure a uniform annular space between the end rings and the body of the pipe and all bolts tightened approximately the same amount. Diametrically opposite nuts shall be tightened progressively and evenly. Final tightening shall be done with a torque limiting wrench set for the torque recommended by the coupling manufacturer.
8.11 Polyvinyl Chloride Pressure Pipe:
A. Elastomeric Gasket Joint: Immediately before joining two lengths of PVC pipe, the inside of the bell or coupling, the outside of the spigot and the elastomeric gasket shall be thoroughly cleaned to remove all foreign material.
Lubrication of the joint and rubber gasket shall be done in accordance with the pipe manufacturer's specifications.
Care shall be taken that only the correct elastomeric gasket, compatible with the annular groove of the bell, is used. Insertion of the elastomeric gasket in the annular groove of the bell or coupling shall be in accordance with the manufacturer's recommendations. Pipe that is not furnished with a depth mark shall be marked before assembly to assure that the spigot end is inserted to the full depth of the joint.
The spigot and bell or coupling shall be aligned and pushed until the reference line on the spigot is flush with the end of the bell or coupling. Pushing shall be done in a smooth, steady motion.
B. Pipe Storage: Pipe stored outside, and exposed to sunlight for more than 30 days, shall be covered with an opaque material such as canvas. Clear plastic sheets shall not be used to cover pipe. Air circulation shall be provided under the covering.
C. Handling of Pipe in Cold Weather: PVC pipe has reduced flexibility and impact resistance as temperatures approach and drop below freezing. Use extra care should be used in handling PVC pipe during cold weather.
D. Underground Location and Warning Tape: Install 6 inch wide detectable aluminum foil plastic backed tape indicating for buried water line below and installed, 12 inches to 18 inches below surface grade. Tape must be blue in color and be manufactured by Thortec or equal.
E. Tracer Wire Installation: Install 12 gauge single strand copper tracer wire to pipe with 2 inch wide PVC tape. Splicing of tracer wire shall be per manufacturer’s recommendation. The tracer wire shall run to a test station or valve box located next to a fire hydrant.
8.12 Installation Of Valves:
Valves shall be handled in such a manner as to prevent injury or damage. Valves shall be set and joined to pipe in the manner previously specified for cleaning, laying and joining mechanical and push on joints. Valves shall be set in such a manner that the valve stems are plumb. Valves shall be wrapped with polyethylene encasement material in accordance with 6.41 A.
Valves shall be located at the point on the main, which would be intersected by the street property line extended and as outlined in 5.10. Any deviations from this shall be at the discretion of Denver Water.
If so ordered by Denver Water, valves shall be operated prior to installation to ensure good operating condition.
8.13 Installation Of Valve Boxes:
A valve box shall be provided for every valve. The valve box shall not transmit shock or stress to the valve, and shall be centered and plumb over the wrench nut of the valve, with the box cover set to the elevation determined by Denver Water. It will be the responsibility of the Applicant to insure that valve boxes are plumb and raised to the proper elevation.
8.14 Installation Of Fittings:
All fittings in Denver and Total Service Areas shall be mechanical joint in compliance with MS-3. Distributor Contract Areas may elect to use push on joint fittings except fire hydrant tees, which shall be mechanical joint. Fittings shall be set and joined in the manner described in 8.10.B. The use of wyes in main extensions or private pipe extensions is strictly prohibited.
Where PVC pipe is inserted into cast iron or ductile iron fittings, beveled portions of the spigots shall be removed to accommodate the expansion characteristics of the plastic to the lesser depth of bell.
All repair fittings and stainless steel repair clamps shall be wrapped with polyethylene encasement material as described in 8.24.C when installed during a main repair.
8.15 Installation Of Tapping Saddles:
A tapping saddle is used to make a wet connection to an existing main without taking the main out of service. A tapping saddle and tapping valve are not a substitute for a property line valve. A valve box shall be installed with the tapping valve.
Tapping saddles may be installed side by side when specifically approved by Denver Water. A 12 inch space shall be required between adjacent saddle plates. In an intersection, two tapping saddles may be used to run lines out of both sides of the pipe if the alignment of the pipe is kept straight out of the tapping saddle. The use of two tapping saddles, either side by side or back to back, as a substitute for a cross is strictly prohibited. A 6 inch tap on a 6 inch main and an 8 inch tap on an 8 inch main will be approved, a 12 inch on a 12 inch main will not be approved.
8.16 Fire Hydrants:
A. Installation: All hydrants shall be field staked for location and grade. Final location shall be in accordance with approved drawings. Fire hydrants shall be set so that the elevation of the center of the traffic flange is 3 inches above the finished grade of the ground or top of the curb. All hydrants shall stand plumb and be installed as indicated on Sheet 7 of the Standard Drawings.
Each hydrant shall be connected to the street main by a 6 inch branch line. The branch line shall be ductile iron pipe only. An independent 6 inch gate valve shall be installed on each fire hydrant branch. The valve shall be firmly anchored to either a mechanical joint tee with a 6 inch anchor coupling (also called swivel adapter or locked hydrant adapter) or to a mechanical joint anchor tee (also called swivel tee or locked hydrant tee).
The fire hydrant branch shall be anchored to the valve by means of megalugs.
Exception: When making a wet tap for a fire hydrant, a tapping valve and saddle shall be used in place of the mechanical joint tee, swivel adaptor and valve.
B. Hydrant Drainage: Drainage shall be provided at the base of the hydrant by placing rock from the bottom of the trench, to at least 12 inches above the barrel flange of the hydrant, and to a distance of 12 inches around the elbow. The minimum distance from the bottom of the trench to the bottom of the hydrant elbow shall be 6 inches. The minimum amount of rock placed shall be 1/3 cubic yard. The rock shall be a well-graded gravel, cobble, or brick size crushed rock.
C. Hydrant Protection from Corrosion: The ductile iron branch line, and fittings, from the hydrant base up to and including the tee, shall be encased in polyethylene wrap. The type of polyethylene and manner in which it is to be installed shall conform to 8.24.C. Bedding and pipe zone material shall be used from a point 6 inches below to a point 6 inches above the branch line. Bedding and pipe zone material shall be as specified in 7.10.B.
8.17 Fireline Connections:
The installation of fireline connections shall conform to Sheet 35 and 36 of the Standard Drawings and to Chapter 3. Fireline connections shall be restrained, ductile iron pipe only. The fireline connection shall have a valve 2 feet from the property line on the street side of the property line. The fireline connection shall be protected from corrosion.
Fireline connections for residential usage only are available in one inch and 2 inch sizes if approved by Denver Water. Requests for these connections must be submitted with drawings to Denver Water for approval.
8.18 Kickblocks:
The following standard shall apply to kickblocks as shown on Sheet 19 and 20 of the Standard Drawings:
A. Installation: Kickblocks shall be constructed at all bends and fittings which require support due to unbalanced line thrust, and which are not restrained. Care shall be taken not to block outlets or to cover bolts, nuts, clamps or other fittings or to make them inaccessible. A bond breaker shall be placed between the pipe and the kickblock to aid in ease of future removal. For the same reason, if a large kickblock is to be placed, it shall be separated into sections by a suitable material. Sheet 19 of the Standard Drawings show sizes and shape of kickblocks. Bearing surface areas are minimum areas to bear against the undisturbed trench wall. If, in the opinion of Denver Water, the soil bearing capacity is not sufficient to provide adequate support based on minimum bearing areas shown on the Standard Drawings, then the minimum bearing area shall be increased to a size that will ensure support restraint. In every instance, the kickblock shall bear against undisturbed earth. When it is impossible, through over excavation or other cause, to place a kickblock against undisturbed earth, restraint shall be required to anchor the fittings to the main.
Before placing concrete, equipment for mixing and transporting the concrete shall be clean. Debris, water or ice shall be removed from the place to be occupied by the concrete. Concrete shall not be placed on frozen subgrade. Concrete shall be placed only in the presence of the Inspector unless inspection has been waived prior to the placement.
B. Formwork for Kickblocks: Forming for concrete kickblocks and anchors will be done by bulkheading around the shape of the kickblock or anchor with wood, burlap sacks, or reinforced paper sacks filled with sand or earth. Sacks shall be of a size easily handled when full, and shall be left in place in the trench. Wood forms shall be removed before backfilling.
If the main must be placed immediately into service, harness rods may be used in lieu of kickblocks or wood may be used to form up kickblocks. Wood forms shall be of such design as to support the thrust until the concrete has set and shall not be considered a substitute for the concrete kickblock.
No horizontal struts or braces required for trench shoring shall remain in the concrete kickblocks. Prior to placing concrete, the forms and ditch bank shall be inspected and approved by Denver Water.
When concrete is deposited against ground without the use of forms, the ground shall be thoroughly moistened or other provisions made to prevent the ground from drawing water from the concrete.
C. Minimum Kickblock Curing Time: Newly placed concrete shall be allowed to set, undisturbed, for a minimum of 24 hours.
D. Compaction of Fill Over Kickblocks: Backfill may be placed over kickblocks once the surface has set sufficiently to resist the weight of the backfill. However, no tamping or compacting shall be allowed above the kickblock for a minimum of 24 hours after placement.
8.19 Concrete Structures:
A. Formwork: Forms shall produce shapes, lines and dimensions of the concrete structures as shown on the Drawings.
The formwork shall be designed according to the loads and allowable stresses set forth in ACI 347.
Forms may be made of wood, metal or other acceptable material approved by Denver Water. The forms shall produce a smooth concrete finish to the tolerances described in ACI 301. Form material with raised grain, torn surfaces, worn edges, patches, dents or other defects, which will impair the texture of the concrete surface, shall not be used.
Forms shall be mortar tight and braced or tied to maintain proper position and shape during and after concrete placement. Embedded metal ties with snap-off ends shall be used for internal form ties. Use of ordinary wire ties is not be allowed. Withdrawal of form ties through the walls will not be permitted.
All exposed edges shall be chamfered with a 3/4 inch, 45 degree bevel.
All surfaces of forms and embedded items shall be cleaned of all foreign material before concrete is placed. The recommendations of ACI 347 for form removal times under normal conditions shall be followed. Denver Water shall determine if additional time is required before form removal.
Forms shall be removed in a manner, which will insure the integrity of the structure and its surfaces.
B. Mixing and Placing: Equipment used in mixing and transporting concrete shall be clean. Debris, water or ice shall be removed from the places to be occupied by the concrete. Concrete shall not be placed on frozen subgrade. Wooden forms shall be thoroughly wetted (except in freezing weather) or a form release agent shall be applied.
Ready-mixed concrete shall be mixed and delivered in accordance with ASTM C 94. Water may be added one time immediately upon arrival at the job site to bring the slump within the required limits.
The concrete shall be conveyed from the mixer to the place of final deposit by methods, which will prevent separation. Equipment for chuting, pumping and conveying concrete shall be of such size and design as to ensure a continuous flow of concrete at the discharge end without separation of materials. Concrete shall not free fall a vertical distance greater than five feet during discharge into the forms.
Concrete shall be deposited as nearly as possible in its final position to avoid segregation due to handling or flowing. Concrete shall be placed at a rate such that it is, at all times, plastic and flows readily between reinforcing steel. Concrete that has partially hardened or is contaminated by foreign materials shall not be allowed.
Concrete shall be deposited continuously in layers of such thickness that no concrete will be deposited on or against concrete, which has hardened sufficiently to cause the formation of seams or planes of weakness within the area or section. Concrete shall not be placed in lifts exceeding 18 inches in thickness.
The accumulation of water on the surface of the concrete due to water gain, segregation or other causes during placement and consolidation shall be prevented by adjustments in the mix design.
When placing concrete during cold weather as defined in ACI 306, the temperature of the concrete mix during placing shall not be lower than 55°F and all concrete work shall follow the recommended practices of ACI 306. When placing concrete during hot weather as defined in ACI 305, the temperature of the concrete mix during placing shall not be higher than 85°F and all concrete work shall follow the recommended practices of ACI 305. Cooling or warming plastic concrete mixtures shall not be undertaken without the approval of Denver Water.
C. Consolidation: All concrete immediately after depositing shall be thoroughly consolidated with internal vibrators as recommended in ACI 309. Denver Water shall approve the size, type and number of vibrators used for each concrete placement. The concrete shall be thoroughly worked around the reinforcing steel, around embedded items and into the corners of the forms. Vibrators shall be supplemented by spading, rodding or forking to eliminate all honeycomb at the form face and voids around embedded items.
D. Finishing: Where concrete surface finishes are not shown on the Drawings, unformed flat surfaces shall be screeded and wood float finished and interior floor surfaces shall be steel trowel with light broom finished to Class A tolerance in accordance with ACI 301.
No wetting of concrete surfaces during slab finishing operations shall be permitted. No concrete finishing operation shall be performed while there is water on the surface.
E. Construction and Contraction Control Joints: Construction joints not indicated on the plans must have specific approval of Denver Water. All concrete surfaces where joints are made shall be thoroughly cleaned and laitance removed prior to placing adjoining concrete. Contraction control joints shall be cut one quarter the depth of the slab. When power saw cutting methods are used, joints shall be cut as soon as the concrete surface is firm enough not to be torn or damaged by the saw blade. Water employed in cutting, washing and rinsing of concrete contraction control joints shall not stain, discolor or affect exposed surfaces of the structures, or damage the environment of the project or adjacent areas. Methods of waste water disposal shall be subject to approval by Denver Water.
F. Curing and Protection: Concrete shall be cured by a method recommended by ACI 308. When the daily mean ambient temperature is above 40°F, the finished concrete shall be cured continuously for a minimum of 7 days or for the time necessary to attain 70% of the specified compressive strength, whichever period is less. When the mean daily ambient temperature is 40°F or lower, the finished concrete shall be continually cured at a minimum temperature of 55°F for the period recommended by ACI 306 to prevent damage from early-age freezing and provide the service category strengths required for each placement.
Concrete curing on formed surfaces shall be initiated immediately after removal of the forms or as directed by Denver Water.
Concrete curing on slabs shall be initiated immediately after the water on the surface of the slab has evaporated or as directed by Denver Water.
G. Surface Repair: Surface defects, including fins, tie holes, and honeycombed areas shall be repaired down to solid concrete in accordance with ACI 301.
8.20 Reinforcing Steel For Concrete Structures:
A. Installation: Reinforcing steel shall be accurately formed to the dimensions indicated on the plans. Bends in bars shall be made cold. Bars with kinks or bends not shown on the plans shall not be used.
Splices shall be located where shown on the plans. Splices at other locations must be approved by Denver Water. Welded wire mesh shall be lapped one space and securely wired together.
Before the reinforcement is embedded in concrete, the surfaces of the bars, and bar supports, shall be cleaned of heavy flaky rust, loose mill scale, dirt, grease, or other foreign substances, which are objectionable. Reinforcement will be inspected for compliance with requirements as to size, shape, length, splicing position, and amount after it has been placed.
B. Placing of Reinforcing Steel: Reinforcing steel surfaces and supports shall be cleaned of flakey rust, loose mill scale, dirt, grease or other foreign substances.
Steel reinforcing bars and welded wire fabric shall be placed accurately within the forms and be well secured with annealed wire before concrete is placed. Steel reinforcing bars in walls shall be tied at a minimum of every other intersection or as directed by the Denver Water. Steel reinforcing bars in slabs shall be tied at every intersection. Steel reinforcement in slabs shall be supported on chairs of metal, plastic or concrete in a manner to prevent any steel reinforcement dislocation during slab construction.
Splices other than those shown on the Drawings shall not be constructed without the approval of Denver Water.
Reinforcing steel shall be protected by the thickness of concrete indicated on the plans. Where not otherwise shown, the thickness of concrete over the reinforcement shall be as follows:
1. Where concrete is deposited against ground without the use of forms, not less than 3 inches.
2. Where concrete is exposed to the weather, or exposed to the ground but placed in forms, not less than 2 inches for bars more than 5/8 inch diameter and 1-1/2 inches for bars 5/8 inch diameter or less.
3. In formed surfaces not in contact with the ground or exposed to the weather, not less than 3/4 inch.
8.21 Joint Restraint Devices:
Joint restraint devices shall be used at all bends and fittings where kickblocks cannot be used due to existing field conditions or where joint restraint devices are specifically required. Joint restraint devices shall be required for the following installations:
1. Fire hydrants
2. Fireline connections
3. Three inch and larger domestic line connections
4. Vertical bends
5. Reducers
6. Vertical and horizontal offsets
7. Bends, line valves and fittings
8. 90° horizontal bends
9. Bulkheads and plugs
10. Bored casings
11. When it is not possible to place against undisturbed earth
12. When, in the opinion of Denver Water, the bearing capacity of the soil is not sufficient to provide adequate restraint
Horizontal and vertical offsets and reducers shall be restrained on each side of the fitting. For all other fittings, the length of tied pipe shall be in accordance with Sheet 21 of the Standard Drawings. All joint restraint devices and appurtenances shall conform to 6.05 D and Sheets 22 through 28 of the Standard Drawings.
8.22 Connections To Denver Water's System:
A. Connections: Connections to Denver Water's system shall be in a neat and workmanlike manner. Denver Water shall be present at all times during the construction of the connection. The connection is subject to approval by Denver Water. Only one connection to the existing system will be permitted until the conditions and tests outlined in 8.27 have been met.
Denver Water does not guarantee water tightness of its valves on existing facilities. If existing valves leak, Denver Water will assist in reducing the leakage, but the Contractor shall use appropriate methods to work with the resulting leakage.
No connection will be installed or allowed by Denver Water unless the water supply is protected as required against actual or potential backflows. Water service to any premise will be discontinued by Denver Water if a backflow prevention device that is required is not installed, tested, and maintained, or if it is found that a backflow prevention device has been removed, by passed, or if an unprotected cross-connection exists on the premises. Service will not be restored until such conditions or defects are corrected.
An approved backflow prevention device shall also be installed on each service line and fireline within a licensee'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:
1. In the case of premises having 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 shall be protected against backflow from the premises by installing an approved backflow prevention device in the service line and fireline appropriate to the degree of hazard.
2. 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 shall be protected against backflow from the premises by installing an approved backflow prevention device in the service line appropriate to the degree of hazard. This shall include the handling of process waters originating from Denver Water's system which haven been subject to deterioration in quality.
3. 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 shall be protected against backflow from the premises by installing a backflow prevention device in the service line.
B. Operation of Valves: In connecting to Denver Water's system, it may be necessary to operate existing Denver Water valves. Valves on Denver Water's system that must be operated to make a connection shall be operated by the appropriate Denver Water personnel only. The Contractor shall give Denver Water 48 hours notice to arrange for operating valves. Both the Contractor and Denver Water shall be present when the valves are operated.
C. Interruption of Service: Installation of a connection that will require closing existing valves may cause an outage of water to existing Denver Water customers. Affected customers shall be notified, in writing, 24 hours in advance. The notices shall be delivered by hand to each residence. An attempt shall be made at each residence to deliver the notice personally to the occupant. If the occupant cannot be contacted, the written notice shall be left at the door. Notification must be done by the Contractor.
The appropriate fire prevention bureau for the affected area shall be notified 48 hours in advance. A description of the boundaries of the affected area, and the location of all fire hydrants in that area shall be provided to the appropriate fire prevention bureau. Notification shall be done by the Contractor.
A normal outage shall be a maximum of 8 hours. If the outage will be greater than 8 hours, the work shall be done in a manner to minimize the inconvenience to customers, such as working at night in a continuous operation until service is restored. A connection which will require an outage longer than 8 hours shall be subject to review by Denver Water as to the appropriate timing of the connection.
If in the process of installing a connection there exists an industry or building in the area that cannot be out of water, such as a hospital, appropriate means shall be taken to provide and convey water. The water and the means of conveyance shall be approved by Denver Water.
8.23 Corrosion Protection Systems:
A. Dissimilar Materials: Cathodic protection and insulation shall be installed as required by Denver Water. Particular care shall be taken to insulate between dissimilar materials.
B. Insulating Joints: Whenever it is necessary to join pipe of dissimilar metal, a method of insulating against the passage of electrical current, approved by Denver Water, shall be provided. Special care shall be exercised during the installation of these joints to prevent electrical conductivity across the joints. After the insulating joint installation is completed, Denver Water will test the joint. Should the insulated joint fail the test, it shall be removed, inspected and any necessary repairs made. The joint shall then be reinstalled and tested. This process shall continue until the joint is successfully tested. Typical insulated joints are shown on Sheet 37 of the Standard Drawings and 6.41.B.
C. Polyethylene Encasement Material: Metallic pipe, joint restraint, fittings, tie rods and appurtenances regardless of soil resistivity, shall be polyethylene encased. The polyethylene encasement shall prevent contact between the pipe and bedding material, but is not intended to be a completely airtight and watertight enclosure.
Polyethylene pipe wrap material shall be applied to line pipe in the manner shown on Sheet 38 of the Standard Drawings, and 6.41. The polyethylene shall have a minimum thickness of 8 mils and conform to MS-13. A 2 inch wide 10 mil thickness polyethylene pressure-sensitive tape shall be used to close seams or hold overlaps. Prolonged exposure to sunlight will eventually deteriorate polyethylene film. Keep exposure to sunlight to a minimum.
Before Denver Water will tap a water main, the trench, pipe and polyethylene wrapping shall be in a state of readiness. Damage to polyethylene pipe wrap in the trench prior to and during backfill shall be repaired to the satisfaction of Denver Water. Damage to the pipe wrap caused by tapping the main shall be repaired by Denver Water.
8.24 Chlorination:
All main extensions and private pipe extensions shall be chlorinated in accordance with AWWA C651, and the local health authority having jurisdiction, prior to acceptance by Denver Water. The chlorinating agent, and method of application, shall be approved by Denver Water.
The chlorination of the finished pipeline shall be done prior to the hydrostatic testing. Before filling the pipe with water, the pipe shall be clean and free of debris to the satisfaction of Denver Water. Denver Water will not provide labor or material for disinfection to Applicant’s installing mains under private contract.
Chlorine tablets may be used for disinfection in 12 inch and smaller pipe. Sixteen inch and larger pipe requires a chlorine slurry fed into the water used in filling the pipe. Chlorine tablets shall be attached to the inside top of the pipe with an approved adhesive certified to NSF Standard 61 prior to the pipe installation in the trench. An approved adhesive is Dow Corning 732 Multi-Purpose Sealant.
| Number of hypochlorite tablets of 5 gram strength required for a dose of 50 milligrams/liter* | ||||
|---|---|---|---|---|
| Pipe Length | Pipe Diameter (Inches) | |||
| (Feet) | 6 | 8 | 12 | |
| 13 or less | 2 | 2 | 5 | |
| 18 | 2 | 3 | 6 | |
| 20 | 2 | 3 | 7 | |
| *Based on 3-3/4 gram available chlorine per tablet. | ||||
After the pipe is filled with water and chlorine, the chlorinated water shall be held in contact with the pipe for 24 hours. At the end of the 24 hour period, the water in the pipeline shall be tested by the local health authority or their designated representative to insure a residual chlorine content of not less than 25 milligrams per liter. Then the pipeline shall be thoroughly flushed to remove the heavily chlorinated water. Care shall be taken in flushing the pipeline to prevent property damage and danger to the public.
Samples of water will be collected for bacteriological examination and residual chlorine content testing before the pipe is put into service. Testing of residual chlorine, and sampling will be done by the local health authority or their designated representative.
8.25 Hydrostatic Testing:
No hydrostatic tests shall be made on any portion of the pipeline until field placed concrete has had adequate curing time as defined for kickblocks in 8.20.F.
Denver Water shall be notified 24 hours in advance of testing. All testing shall be made in the presence of Denver Water.
Only the following methods are acceptable for supplying potable water for hydrostatic testing:
1. Water may be taken from a nearby pressurized water source which has been previously chlorinated, tested and accepted, such as a fire hydrant.
2. Water may be delivered to the site in a chlorinated water truck having a minimum capacity of 300 gallons. The water truck shall be used exclusively for the transportation of potable water.
3. Any previously tested, chlorinated and accepted water main, which is pressurized and is to serve the new main extension may be tapped on the pressurized side of the closed valve.
In any event, the method of supplying water as well as the source of water for hydrostatic testing must be certified and approved by Denver Water. Use of barrels, sanitary or otherwise, to supply water for hydrostatic testing is strictly prohibited.
Denver Water will furnish only the calibrated meter but not the pump for testing. The pipeline shall be properly backfilled and shall be in a state of readiness for testing. All bulkheads, pumps, taps and appurtenances necessary to fill the pipeline and maintain the required pressure shall be in place. The pipeline shall be filled with water and the test pressure of 150 pounds per square inch shall be applied to the pipeline by means of a continuously operating pump, equipped with a bypass valve for regulating pressure. When filling the pipeline, it shall be filled at a rate, which will not cause any surges, nor will it exceed the rate at which the air can be released.
All air in the line shall be properly purged. Where blowoffs or hydrants are not available or are not effective in purging air from the line, Denver Water shall require a tap to purge the line. The location and size of tap shall be at Denver Water's discretion.
While the test pressure is maintained, an examination shall be made of the pipeline in general, and any leaks shall be repaired. Any pipe or fitting found to be faulty shall be removed and replaced. No leakage is allowed through the bonnet of the line valve. Any valve leaking through the bonnet shall be repaired in place or removed and replaced. Cutting and replacing pavement, excavating and backfilling may all be necessary parts of locating and repairing leaks discovered by pressure testing of pipe.
After all visible leaks have been stopped, the full test-pressure shall be maintained for 2 continuous hours. Allowable leakage for each section between line valves shall not exceed the following leakage rates for 4 inch through 20 inch distribution and transmission mains:
| Allowable Leakage | ||||
|---|---|---|---|---|
| Pipe Size (Inches) | Per 1,000 Feet of Pipe (Gallons Per Hour) | |||
| DI | PVC | |||
| 4 | .37 | .33 | ||
| 6 | .55 | .50 | ||
| 8 | .74 | .66 | ||
| 12 | 1.10 | 1.00 | ||
| 16 | 1.47 | |||
| 20 | 1.84 | |||
The amount of leakage in the 24 inch and larger conduits shall be identified in project specifications.
Should testing show a leakage rate in excess of the rates shown, the pipeline shall not be accepted. The pipeline shall be repaired, rechlorinated as described in 8.25 and retested until it meets the test requirements.
8.26 Acceptance And Release For Taps:
A main shall be accepted by Denver Water and released for taps when the following conditions have been met:
A. Installation: The main and all appurtenances have been installed to the satisfaction of Denver Water and all pertinent notes and measurements have been made.
B. Tests: The following tests have been passed and notification of passing has been sent to Denver Water:
1. Chlorination test and any other test(s) required by the local health authority; see 8.24.
2. Compaction test performed under the direction of a Registered Professional Engineer indicating the trench backfill meets Denver Water requirements; see 7.11.
3. Hydrostatic test; see 8.25.
4. Valve and valve box inspection; see 8.13 for installation.
C. Location: In Denver and Total Service areas, all surface features of the water facilities have been located and documented under the supervision and responsibility of a Land Surveyor, registered in the State of Colorado, by GPS or other survey methods. Values of these features shall have a positional accuracy not to exceed three centimeters (3 cm) and will be submitted to Denver Water by acceptable electronic media. These values shall be in a coordinate system readily equated to NAD83 State Plane Coordinates, or Denver Water’s Metro Grid Coordinate System. If the submittal is in a system to be converted to NAD83 State Plane Coordinates, detailed and complete instructions for conversion shall accompany the submittal. These values are intended to serve as the basis for the final "As-Built" plans of the project.
8.27 Blowoff Assembly:
In all installations where the main will be permanently deadended, such as a cul-de-sac, a blowoff assembly shall be installed. Where the main will be temporarily deadended, such as the boundary of a subdivision filing, a blowoff shall be installed, unless a fire hydrant, which can serve additionally as a blowoff, is located at the main's temporary end. The blowoff shall be installed at a right angle to the main and on the side that will allow the water to drain away from the main to the nearest gutter.
The standard required blowoff assembly for 12 inch and smaller mains shall be a 2 inch as shown on Sheet 12 of the Standard Drawings. Under special conditions, such as a long run with few taps, a nonstandard blowoff larger than 2 inch may be required.
The standard required blowoff for 16 inch and larger ductile iron pipe shall be a 6 inch as shown on Sheet l3 of the Standard Drawings.
8.28 Sewer Crossing:
When, during the course of installation, the main or associated piping crosses over or under a sanitary or storm sewer constructed of either vitrified clay or concrete pipe, the sewer shall be replaced or protected as shown on the plans and as described below or as otherwise directed by Denver Water.
When the sewer is 15 inches or less in diameter and crosses over the water main or associated piping, and protection is not otherwise shown on the plans, where applicable, the sewer shall be replaced with poly-wrapped Special Class 50 ductile iron pipe manufactured in accordance with AWWA C151 or Type PSM SDR 35 PVC sewer pipe manufactured in accordance with ASTM D 3034. Re-connections to the existing sewer pipe shall be made with watertight, flexible couplings approved by Denver Water and the Authority having jurisdiction over the sewer being replaced. All drains that exist under the sewer shall be restored in a manner that will prevent any flow in the drain from entering the trench in which the water main or associated piping is installed.
If the sewer is greater than 15 inches in diameter, all necessary precautions shall be taken to protect the sewer during installation of the main or associated piping. All drains that exist under the sewer shall be restored in a manner that will prevent any flow in the drain from entering the trench in which the water main or associated piping is installed.
When the water main or associated piping crosses over the sewer with less than 2-foot clear distance between the pipes, the sewer shall be encased with a minimum of 6 inches of concrete from springline to 6 inches above the top of the sewer. The encasement shall extend along the centerline of the sewer a minimum of one foot beyond the OD of the water main or associated piping at each end of the encasement.
In addition, when the water main or associated piping crosses under a sewer, the bedding material shall be replaced around the sewer to a point at least one foot above the top of the sewer pipe for sewers 15 inches in diameter and smaller and to at least springline for sewers larger than 15 inches in diameter, and thoroughly compacted and consolidated to support the sewer.
Sewers may not be cut without the express consent of the authority having jurisdiction over the sewer.
See Sheet 32 of the Standard Drawings for typical trench sections.
Engineering Standards - Chapter 8:
Revised 07-04, Previous Revision 05-02
End