(A) Hydraulic analysis. The design of all water mains shall be based on a hydraulic analysis considering flow demands and pressure requirements.
(1) The main must be designed to maintain a minimum normal working pressure of 35 psi and maintain an absolute minimum pressure of 20 psi under all flow conditions.
(2) Maximum normal working pressures should not exceed 110 psi.
(B) Fire flows.
(1) All mains shall be designed to provide adequate fire flows, unless specifically waived by the PWD.
(2) The minimum required fire flow shall be 1500 gpm for residential housing or determined by the City Fire Chief at a minimum of 20 pounds per square inch residual pressure at the hydrant during flow in order to meet adopted codes.
(C) Diameter. All water main piping shall be at least eight inches in diameter, unless otherwise authorized by the PWD.
(1) Larger diameters will be required in order to maintain the minimum pressure requirements of Montana Circular DEQ-1 Standards for Water Works.
(2) The city also may require over sizing of mains to meet overall system requirement.
(D) Materials.
(1) Piping.
(a) All water main piping material shall be AWWA C900, 235 psi (DR 18), unless specifically authorized by the City Public Works Department.
(b) Water mains larger than 12 inches will meet AWWA C905 pipe requirements.
(2) Acrylonitrile butadiene (NBR). Acrylonitrile butadiene (NBR) gaskets will be required for water main installations in areas of known or suspected hydrocarbon contamination.
(3) Fittings.
(a) All water main fittings, including tees, crosses, caps, plugs, reducers and elbows equal to or greater than 11-1/4° shall use mechanical joint restraints.
(b) All mechanical joint restraints shall be “Megalug,” “Uniflange” or approved equal. Joint restraint use shall be in addition to meeting thrust block requirements in accordance with MPWSS.
(E) Installation.
(1) Existing valve operation.
(a) In order to isolate sections of the existing water system to allow for new construction, it will be necessary to operate existing system valves.
(b) The PWD must operate existing valves and notification and scheduling, thereof must be coordinated with the PWD.
(2) Cover. The minimum cover for all water mains from top of pipe to final finished grade shall be six and one-half feet.
(3) Encasement.
(a) All water main piping, fittings, valves and the like (excluding PVC pipe) shall be encased in polyethylene wrap with a minimum thickness of eight mils.
(b) All encasement shall be in accordance with AWWA C105 standards.
(4) Electrical thawing.
(a) Conductive brass wedges shall be installed at all joints to provide for electrical thawing.
(b) Electrical continuity shall be provided at all flexible, dresser-type couplings.
(5) Tracer.
(a) Ten-gauge copper coated tracer wire shall be installed along the top of the new PVC water main and shall be attached to all valve box risers.
(b) Six-inch wide detectable tape marked “WATER” shall be installed two feet below finished grade along the alignment of the new main and attached to all valve box risers.
(6) Cathodic protection. Cathodic protection is required for all water main valves, fire hydrants and fittings.
(7) Open trenches. Trenches for the installation of water mains shall be properly backfilled as quickly as possible, but no more than 72 hours after initial excavation.
(8) Protection of mains.
(a) When working near and/or exposing existing city water mains and service lines, workers shall utilize hand-digging within two inches of mains in order to avoid damage to those pipes.
(b) If damage occurs, costs incurred by the city can be imposed.
(F) Extension.
(1) (a) Any extension of an existing city water main must be extended through the entire frontage length of the property to be served.
(b) Main extensions shall include all valves, pipe sizes, hydrants and appurtenances deemed necessary by the city.
(2) Public mains must be connected, extended or looped, in addition to the proposed extension to provide an adequate and functional water supply, and provide for future extensions to adjacent properties.
(G) Sewer line crossings.
(1) Crossings. A minimum of 18" vertical separation is required when a water main or service connection crosses above or below a sanitary sewer, measured outside to outside of pipe.
(a) Please refer to MPWSS for further information on sewer line crossings.
(b) Less than 18" vertical separation may be allowed when a gravity sewer at the crossing is made from a single 20' length of AWWA pressure pipe and the crossing is approximately 90°.
1. Specific authorization from the Montana Department of Environmental Quality and the PWD is required for a vertical separation of less than ten feet.
2. No exception of the minimum 18" vertical separation requirement is permitted when the sewage pipe is a force main.
(2) Parallel. A minimum of ten feet horizontal separation is required when a water main and sanitary sewer are installed parallel.
(H) Tapping city water.
(1) The PWD shall tap all water mains for services up to one inch in size.
(a) Preparations for exposing the water main and preparing the water main for tapping, as well as scheduling for the PWD to make the tap are all responsibilities of the water main installer.
(b) The City PWD can be contacted at 406-846-2238, ext. 300. All taps require at least 48-hour notice and if a tap requires a main shutdown, 72-hour notice is required, and the contractor is required to notify the affected water users.
(2) Any person desiring to make connection to the city’s water or sewer mains must make application in writing and pay for the cost of tapping and any associated system development fees set by the city.
(a) All taps shall be made using a Mueller or Ford style FS303 stainless steel saddle for AWWA C900, DR-14 Class 200 PVC pipe.
(b) Taps of sizes three-fourths inch to one inch on water mains require the city to do a direct tap and provide a properly sized corporation valve.
(c) Special provisions apply for three-fourths inch and one inch taps on four-inch mains. For integrity of the main, these taps require the use of a properly sized tapping saddle, which is required to be purchased and supplied by the plumbing contractor.
(3) (a) Taps for sizes one and one-half inch and two inch on all sizes and types of mains require a properly sized tapping saddle and corporation valve purchased and supplied by the plumbing contractor.
(b) Bronze or stainless-steel double strap or wide band tapping saddles are required on service lines up to two inches in diameter.
(4) (a) Taps of larger than one inch must be performed by a licensed, qualified contractor and require a tapping saddle, tapping valve and a valve box to be purchased and supplied by the plumbing contractor.
(b) All taps four inches and larger must be air tested prior to tapping.
(5) On all taps that require a saddle, the plumbing contractor must provide and install the saddle.
(I) Valves.
(1) Valves shall be installed in the distribution system at sufficient intervals to facilitate system repair and maintenance as determined by the Public Works Department, but in no case shall there be fewer than one valve every 600 feet.
(a) Generally, there shall be two valves on each tee and three valves on each cross.
(b) All gate valves shall conform to AWWA C515 standards and shall open clockwise.
(c) All butterfly valves shall conform to AWWA C504 standards and shall open clockwise.
(2) All tapping valves shall open counterclockwise.
(3) (a) All water valve boxes shall have a concrete collar installed after paving and final grade adjustment.
(b) All water valve boxes shall be aligned to allow a four-inch diameter PVC pipe to be inserted in the valve box and centered over the valve nut.
(4) All water valve boxes will not be extended more than 50% of the total adjusting range.
(J) Fire hydrants.
(1) Unless otherwise approved by the Fire Chief, the hydrants shall be spaced no further apart than one standard city block, which is approximately 500 feet.
(a) The Fire Chief reserves the right to require additional fire hydrants if the demand of the structure(s) requires more flow than the minimum spacing provides.
(b) The placement of all hydrants shall be subject to approval of the City Fire Chief and the PWD.
(2) (a) Fire hydrants shall be 250 psi, five and one-fourth inch, three-way, “Mueller Super Centurion 250,” or approved equal, conforming to AWWA C502 standards.
(b) All hydrants shall be painted red above the ground line.
(3) (a) All hydrants shall be equipped with a #4 pentagon (one and one-fourth inch) operating stem nut and shall open in a clockwise direction.
(b) The direction of opening shall be indicated by a permanent arrow on the hydrant top.
(4) All hydrants shall be designed for final grade of hydrant safety flanges set at one and one-half to three inches above finished grade.
(a) Minimum cover depth on the hydrant lead shall be six and one-half feet with a maximum of eight and one-half feet.
(b) All hydrants shall have a solid one-piece operating stem; the use of a hydrant extension will only be allowed with prior approval of the PWD and no other option exists.
(c) Pipe deflection on hydrant leads shall be minimal and shall not result in finished hydrant more than 1° out of plumb.
(d) The hydrant auxiliary valve shall be located in the street pavement or boulevard with a standard water valve and concrete collar.
(e) No valves or collars shall be located within the curb and gutter.
(K) Water vaults. All underground vaults and manholes associated with the city’s water system shall be constructed of pre-cast concrete sections meeting ASTM C478 or C858.
(1) Vault manhole covers shall have the word “water” cast into the top surface.
(2) All water vault manhole frames shall have a concrete collar patch poured after paving and final grade adjustment.
(Prior Code, § 11.05.010.020) (Ord. 2019-9, passed 9-3-2019; Ord. 2021-15, passed 12-20-2021)