Chapter 13.20
WATER SYSTEM CONSTRUCTION SPECIFICATIONS
Sections:
13.20.010 Applicability.
The water distribution system for any subdivision or addition to the town shall be designed in conformance to the detailed criteria set forth in this section. [Ord. 419 Appx. 1 § 1, 1976. 1996 Code § 7-109.]
13.20.020 Agreements.
To assure continuity of the present town system, owners of areas platting within one mile of the town boundaries shall negotiate written agreements as to the timing, design and construction of water supply and distribution facilities prior to the mayor’s signature being signed on any plats within such one-mile area. Such agreements may also call for the time of annexation of such parcels. [Ord. 419 Appx. 1 § 1, 1976. 1996 Code § 7-110.]
13.20.030 Permit.
Water distribution facilities coming within the scope of these regulations shall be constructed only after a permit for construction has been issued by the town. The permit will not be issued until after plans and specifications covering the proposed construction have been submitted to the town and approved by the town engineer. [Ord. 419 Appx. 1 § 1, 1976. 1996 Code § 7-111.]
13.20.040 Generally.
In general, the water distribution system shall be designed so that it is capable of furnishing the required design flow which includes maximum business and residential demand and fire flows simultaneously.
The water distribution system for any subdivision or addition to be served by the existing municipal water supply system shall be designed so that it can deliver the required design flow to the subdivision or additional or to any portion thereof served by an individual street main with the resulting residual pressure at any point to be less than 20 pounds per square inch. In addition, transmission and feeder mains to the subdivision or addition shall have sufficient capacity to also serve contiguous or adjacent areas which may be expected to be developed within a reasonable period in the future. Contiguous or adjacent areas to be provided for shall be as designated or approved by the town planning commission.
The design of the water distribution system serving any subdivision or addition shall conform to the long-range water distribution system plan as adopted by the planning commission and shall incorporate in the layout the principal transmission and feeder mains provided for in the long-range plan or those portions thereof that are within the boundaries of the area being developed. Features of the long-range plan shall be incorporated into the design of the particular addition or subdivision. [Ord. 419 Appx. 1 §§ 1, 2, 1976. 1996 Code § 7-112.]
13.20.050 Inspection.
There shall be no installation or backfill of any new water pipeline which will be or might become a part of the town water system unless a representative of the town engineer is present. All costs for inspection shall be paid for by the installer. [Ord. 419 Appx. 1 § 3, 1976. 1996 Code § 7-113.]
13.20.060 Plans.
Three complete copies of plans and specifications covering the proposed construction shall be submitted for approval. In general, plans shall consist of a detailed layout of the area to be served by the proposed construction, including any contiguous or adjacent areas which might be affected, together with sufficient details or supplemental drawings as may be necessary for complete review of the proposed construction.
Plans for water and sewage facilities may be combined in the same set of drawings. Plans for water distribution shall show the exact location of all water mains with respect to property lines and the proposed location of valves and fire hydrants. All plans must show the location and, where applicable, the elevation of existing facilities to which the proposed construction will connect, together with the location of other existing utilities which might be affected by the proposed construction. Specifications covering the materials to be used and construction requirements shall accompany the plans when presented for approval.
Plans shall be drawn on standard plan and profile sheets no larger than 24 inches by 36 inches and bound with the details and cover sheet of the same size.
All elevations shown on the plans shall be referenced to mean sea level and referenced to a USGS benchmark or town benchmark run from such USGS elevation. Benchmarks used for the preliminary and construction surveys shall be shown on the plans.
In compliance with state statutes, all designs, plans and specifications shall be prepared by a registered professional engineer licensed to practice in the state, and shall be submitted to the State Department of Environmental Quality, Water Quality Division, for their approval.
Within 30 days after completion of construction, one reproducible copy and two sets of prints of “as constructed” drawings shall be submitted for the permanent records of the town. [Ord. 419 Appx. 1 § 4, 1976. 1996 Code § 7-114.]
13.20.070 Materials.
All water mains shall be constructed of either cast iron pipe or ductile iron pipe with the pipe fittings, valves and other underground appurtenances as previously approved for specific locations; such underground pipes shall be protected by the use of a sand envelope backfill. Plastic pipe may be used within the platted areas of the town if it conforms to AWWA 6-900-75 Standard; minimum class 150 (SDR 18) with cast iron dimensions and rubber ring joints; and plastic pipe may be used outside the platted areas of the town if a master meter is installed at the termination of the town mainline; provided, the plastic pipe conforms to the standards set forth previously or to the Uniform Plumbing Code (minimum pressure rating of 160 PSI). If, in the judgment of the town engineer, any proposed waterlines in unplatted areas might possibly be extended in the future so that they would then become a part of the town water system, those waterlines may use plastic water pipe that conforms only to the standard set forth above. Installation and backfill of all new water pipelines which will be or might become a part of the town water system shall conform with Class B, Class C or Class D as detailed in ASCE Manual No. 37 (6) or with the recommended practices given in ASTM D 2321 (7) along with the recommendations of the pipe manufacturer and the town engineer.
Cast-iron pipe shall be designed for 150 pounds per square inch working pressure and five feet of cover with half-thickness cement lining and shall meet the requirements of AWWA standard C106 for one cast-iron pipe centrifugally cast in metal molds, or AWWA standard C108 for cast iron pipe centrifugally cast in sand-lined molds. Pipe shall be furnished with the single gasket push-on joint.
Copper service pipe shall meet the requirements of ASTM standard specification B88 for seamless copper water tube, type K. Fittings shall be equal to Mueller H-15430 (copper tube nut), and H-15400 (three part union). Corporation cocks shall be an all bronze cock Mueller thread inlet and copper service pipe outlet equal to Mueller H-15000. Meter yokes shall be Ford or equal with inlet valve or an approved equal. Curb valves shall be Ford ball or Mueller Oviseal or equal.
Ductile iron pipe shall be designed for 150 pounds per square inch working pressure and five feet of cover, with half-thickness cement lining, meeting the requirements of AWWA Standard C151 for ductile iron pipe, centrifugally cast on metal molds or sand-lined molds. Pipe shall be furnished with the single-gasket push-on joint.
All fire hydrants shall be the Mueller A-24015 AWWA improved type with a six inch flanged inlet with two and one-half inch hose nozzles, one four inch pumper nozzle, a five-and-one-quarter-inch main valve, national standard hose threads and standard pentagon operating nut or equal. Hydrants shall be designed for a pipe depth of five feet (to top of pipe). Each hydrant shall be installed with a six inch flange x mechanical-joint auxiliary gate valve meeting the requirements previously specified.
Gate valves shall be iron-body, bronze-mounted, double-disc, parallel-seal valves meeting the requirements of AWWA Standard C500 for gate valves for ordinary water works service. All valves shall have nonrising stems and be furnished with “O-ring” packing. Valves shall be provided with a standard two inch square operating nut and shall open counterclockwise. Valves shall be equipped with mechanical-joint ends. Flange ends for hydrant auxiliary valves shall meet the requirements for ASA Class 125 cast iron pipe flanges with bolt holes straddling centerlines.
Valve boxes for both main line and hydrant auxiliary valves shall be a standard cast iron, two piece, screw-type adjustable valve box of correct size for the valve designed for a normal five-foot bury of the pipeline (to top of pipe).
Pipe fittings for either cast iron or ductile iron pipe shall meet the requirements of AWWA Standard C110 for cast iron pressure fittings. Except where otherwise specified by the town engineer, fittings shall be equipped with mechanical-joint couplings conforming to ASA Standard A21-11 for a mechanical joint for cast iron pressure pipe and fittings. [Ord. 419 Appx. 1 § 5, 1976. 1996 Code § 7-115.]
13.20.080 Installations.
(a) Generally. Trenches and excavations shall be kept free from water during excavation, fine grading, pipe laying and jointing. Where the trench bottom is mucky or otherwise unstable because of the presence of groundwater and in all cases where the static groundwater level is above the bottom of the trench, the groundwater shall be lowered by means of pumps or well points to the extent necessary to keep the trench free from water and the bottom stable.
The bottom of the trench at pipe grade shall be clean and free from rock, boulders or hard lumps and graded to provide a uniform and continuous bearing and support for the pipe on solid and undisturbed soil at every point between bell holes. Bell holes of sufficient size to permit the proper making up of joints shall be provided at each joint.
(b) Trench Depths. Trenches for water mains shall be excavated to provide a minimum depth of cover of five feet over the top of the water main unless otherwise directed. Greater depths may be required beneath existing utilities and in making connections to existing mains.
Trenches shall be excavated to provide a uniform and continuous bearing and support for the pipe on solid and undisturbed soil at every point between bell holes. The sub grade beneath the center-line of the pipe shall be fine-graded by hand immediately ahead of the pipe laying operation and shall be finished to a uniform grade between the pipe joints. Bell holes of sufficient size to permit the proper making up of joints shall be provided at each joint.
(c) Trench Widths. Trenches shall be of sufficient width to provide ample working space in handling pipe and fittings and the making up of joints, but shall not be less than 12 inches greater than the nominal pipe diameter.
(d) Backfill. Trenches shall be backfilled immediately after the pipe installation has been approved for backfilling. All backfill material shall be carefully placed to avoid displacement or damage to the pipe or adjacent structures. Backfill from the bottom of the trench to approximately one foot over the top of the pipe shall be placed by hand unless otherwise approved, taking particular care to completely fill under the pipe haunches. This portion of the backfill for the full width of the trench shall be carefully compacted either by hand or by mechanical compaction equipment.
(e) Backfill from approximately one foot over the top of the pipe to the surface of the ground or pavement sub-grade where applicable may be placed by either hand or equipment, and shall be thoroughly compacted by either placing the backfill in 12-inch maximum lifts and compacting each lift by mechanical tamping equipment or by partially filling the trench in maximum lifts of three feet and compacting each lift with a mobile trench operator.
(f) Backfill Material. From the bottom of the trench to at least one foot over the top of the pipe backfill material shall be material as excavated from the trench selected to eliminate rock, stones, or similar hard objects that might damage the pipe during subsequent backfill compaction or future earth movement or settlement. The remaining backfill shall be material as excavated from the trench without selection.
(g) Grade and Alignment. Grade or water mains shall be as established in the field to provide the minimum depth of cover previously specified. Alignment of water mains shall be as shown on the drawings unless otherwise directed by the town engineer.
(h) Handling Pipe and Fittings. Handling, unloading from trucks and installation of all pipe, fittings, valves, hydrants and other materials shall be by such methods as will ensure their final installation in a sound and undamaged condition. Pipe and fittings shall under no circumstances be dropped to the ground from trucks or otherwise subjected to possible damage from impact, but shall be unloaded by means of hoists, cranes or by skidding. Pipe and fittings shall be lowered into the trench by means of hoists, booms and ropes.
(i) Installing Pipe and Fittings. Cutting of cast iron or ductile iron pipe shall be done with mechanical pipe cutters or metal-cutting power saws in such a manner as to avoid damage to the pipe and leave a smooth cut at right angles to the axis of the pipe. Where using a push-on joint the cut end shall be tapered with a grinder or file about one-eighth inch back at an angle of about 30 degrees. The interior of all pipe shall be cleaned of all foreign material before being installed and shall be kept clean until the work has been inspected and accepted. When pipe laying is stopped at the end of a day’s work or for any other reason, the open end of the pipeline shall be kept sealed with a watertight plug. It is essential that no mud, trench water or any foreign material of any kind be permitted to enter the pipeline.
During installation each pipe length and fitting shall be carefully inspected for defects. Defective pipe and fittings shall be either rejected or salvaged by cutting off the damaged portion.
In making up mechanical joints it is important that the entering spigot is centered in and that the gland or follower ring is parallel to the face of the connecting bell. Deflections in the pipe joint shall be made after the bolts have been slightly and uniformly tightened. Final tightening shall be done using a ratchet wrench or impact wrench with a torque of between 60 and 90 foot-pounds bringing the follower gland towards the bell face evenly by alternate tightening of the bolts. As in the push-on joint it is essential that the gasket and surface of the pipe that will be in contact with the gasket are wiped clean before assembling the joint.
(j) Valves and Valve Boxes. Valves and boxes shall be set plum with each valve box placed directly over the valve and with the top of the box adjusted to be flush with the finished grade. After the valve box has been placed in position backfill material shall be carefully placed and thoroughly compacted around the valve and box to the full trench depth. After installation is completed each valve shall be checked with a valve key to determine if the key can be readily set on the operating nut.
(k) Fire Hydrants. Before installing, each hydrant shall be checked to see that the hydrant valve is clean and that the hydrant is in operating condition. Prior to setting a pit approximately two feet square and two feet in depth shall be dug below the centerline of the hydrant and filled with coarse gravel or crushed rock. The hydrant and auxiliary gate valve and box shall be set plum and braced into position until backfill with the elevation of the hydrant being set as directed. After bracing and after application of the polyethylene corrosion protection wrap, a concrete thrust block shall be installed back of the hydrant and additional gravel placed to a depth of about one foot over the top of the pipe completely surrounding the hydrant and auxiliary gate valve. The remaining backfill shall be placed and thoroughly compacted around the hydrant barrel to the full trench depth.
(l) Service Connections. All service connections from the street main to the water meter, regardless of the location of the meter, shall be constructed of copper water tube or service pipe with copper water tube flared fittings. Minimum size of any service shall be three-quarters of an inch. All service lines shall be installed to provide a depth of cover over the pipe of not less than five feet.
The town’s public works department will furnish the corporation cock and make the main tap and will furnish for installation by the installer the copper water tube and fittings from the street main to the meter, the meter vault and the meter yoke. Where the water meter is installed within a house or other structure, the town will furnish the copper water tube from the street main to the curb stop adjacent to the property line, the curb stop and the meter yoke, with the installer to furnish the copper water tube and fittings from the curb stop to the meter location. [Ord. 419 Appx. 1 § 6, 1976. 1996 Code § 7-116.]
13.20.090 Testing.
Before final acceptance of the work by the town the water mains between valved sections shall be filled and tested for leakage at a pressure of 150 pounds per square inch for a period of not less than one hour. Leakage must not exceed 25 gallons per inch of diameter per mile of length per 24 hours. Where the leakage is in excess of this amount the installer shall locate and repair any leaks until the pipeline or main meets the leakage limitations. Test pump, pipe connections, pipe taps and similar facilities shall be furnished by the installer. Test gauges will be provided by the town. [Ord. 419 Appx. 1 § 7, 1976. 1996 Code § 7-117.]
13.20.100 Design.
(a) Design Flows. The design flow to be used for the sizing of the feeder and street mains shall be the calculated maximum domestic daily water demand based on the anticipated number of service connections with allowance for future areas to be served in the case of feeder mains plus the required fire flow to be provided.
The maximum domestic daily water demand shall be based on an allowance of 100 gallons per capita per day average water use times a factor of two and five-tenths to obtain the maximum per capita daily demand or 375 gallons per day. Allowing four persons per connection, the maximum daily demand per service connection will be 1,500 gallons per day or one and four-one-hundredths gallons per minute.
This maximum daily demand per service connection is based on an area having 500 service connections or more. For a lesser number of service connections, the above maximum daily demand shall be multiplied by the following diversity factors:
|
Number of services |
Diversity factor |
|---|---|
|
50 or less |
1.50 |
|
100 |
1.30 |
|
250 |
1.20 |
|
500 |
1.00 |
Straight line interpolation shall be used for a number falling between those listed.
The required fire flow to be added to the maximum domestic daily water demand to obtain the design flow for sizing of water mains shall be as follows:
|
Type of construction |
Fire flow |
|---|---|
|
Residential |
1,000 gallons per minute |
|
School (in residential area) |
1,250 gallons per minute |
|
Institutional (hospital, nursing home, etc.) |
1,500 gallons per minute |
|
Commercial |
1,750 gallons per minute |
For use in determining the variation in operating water pressures, as subsequently specified, the anticipated peak hourly demand shall be the computed maximum domestic daily water demand multiplied by a factor of two.
(b) Fire Hydrants. In accordance with the recommendations of the appropriate bureau, fire hydrants shall be located so that each hydrant will serve an area of not more than 120,000 square feet, requiring a maximum hydrant spacing of 390 feet. In addition, a fire hydrant shall be located at each street intersection with the immediate hydrants along each street being approximately evenly spaced. Additional hydrants may be required where access to other hydrants needed in fighting a fire at a specific location may be blocked or excessive lengths of hose lines required.
Hydrants shall be installed at the exact location back of the street curb as designated by the town engineer. Intermediate hydrants along a street shall be located on the extension of lot lines.
(c) Layout. The layout of the water distribution system for any subdivision or addition shall consist of a closed-loop grid system with no dead-ends or stud mains.
Where a subdivision is being developed, it shall be planned so that each stage of development will be served by a close-loop section to be installed prior to any lot being served by the municipal water system.
Feeder or other water mains that can serve adjacent areas shall be provided with the required tees, crosses and valves as approved by the town engineer to facilitate connections to the main in the future.
All water mains, valves, hydrants and other water supply appurtenances shall be installed within the public dedicated streets or, if approved by the town engineer, in dedicated public easements having unrestricted access at all times with the easement to carry restrictions running with the land prohibiting construction of fences, structures or plantings that restrict, interfere or hinder access for maintenance, repair or replacement of the water main. Preferably, where such easements are planned, a dedicated public alley shall be provided.
All water mains shall be installed within the streets or other public ways at the exact location with respect to the street or property lines as designated by the town engineer. On curbed streets, the water mains shall be laid on a curve at the designated distance from the centerline of the street of the respective property line. No water mains or water main appurtenances shall be installed under curbs, gutters or sidewalks, or on private property, except service lines under crossings.
(d) Minimum Size. The minimum size of any public water mains shall be six inches, including branches to fire hydrants.
(e) Service Connections. Individual water service lines will be required for each lot or residence to be served. Dual service to more than one residence or more than one lot from a single service line connected to the street main will not be permitted.
In all subdivisions water service lines shall be extended to the meter location or curb stop at each lot prior to the installation of curbs, gutters or street paving.
(f) Valves. Valves shall be provided at the end of each street main and at immediate points along the main so that not over one block will be placed out of service in the event water main repairs are required. Maximum spacing of valves in a residential area and on feeder mains serving the area shall be 800 feet. Maximum spacing of valves in a commercial area or on street or feeder mains serving a commercial area and an adjacent residential area shall be 500 feet.
At points where water mains intersect no fewer than two valves will be required at a tee intersection and no fewer than three valves at a cross intersection.
All valves shall be uniformly installed on street or property lines extended unless otherwise designated by the town engineer.
(g) Water Pressure. The minimum static water pressure to be provided at the street main shall be 35 pounds per square inch with the preferred minimum static water pressure to be 40 pounds per square inch. The maximum static water pressure shall not exceed 110 pounds per square inch.
The normal maximum variation in water pressure at any point between the static pressure and the operating pressure during peak hourly demands, not including fire flow, shall not exceed 35 pounds per square inch. [Ord. 419 Appx. 1 § 2, 1976. 1996 Code § 7-118.]