City of Hermann, MO Water Supply Design Specifications

[Ord. No. 1620 §1, 9-25-2006]

General. Proposed extensions of the water distribution system shall, in general, follow the pattern established in the water facilities plan as adopted by the City of Hermann. Deviations from this general policy may be deemed necessary by the City's consulting engineer should the provision of adequate service to prospective customer or fire protection needs, existing or anticipated, in the area to be served warrant said deviations. No public water line shall be constructed less than size (6) inches in diameter (except for two (2) inch PVC lines permitted on cul-de-sacs).

Location Of Water Mains And Appurtenances. Proposed water mains shall be so located within street right-of-way to provide the least interference with the location of other utility lines. Street grades and elevations of proposed main shall be taken into consideration so that once constructed they will not require regrading or relocation.

Depth. All water mains shall have a minimum cover of forty-two (42) inches.

Material Of Construction. Ductile iron pipes, HDPE or PVC shall be used for all mains constructed in the City of Hermann.

The ductile iron shall conform to ANSI A21.51; ASTM A536, Grade 60-42-10; AWWA C151. The minimum nominal thickness class for ductile iron pipe shall be fifty (50), unless otherwise designated by the City's consulting engineer.

Joints, unless otherwise specified, shall be of the push-on type conforming to ANSI A21.11/AWWA C111, except gaskets shall be synthetic rubber. Natural rubber will not be acceptable. The pipe shall be cement mortar lined, conforming to ANSI A21.4/AWWA C104 and shall be coated inside and out with a bituminous coating.

Ductile-iron fittings shall be complete with all accessories and shall be ASTM A536, Grade 7050-05 conforming to ANSI A21.10/AWWA C110, 350 PSI pressure rating. Joints shall be of the standard mechanical joint type conforming to ANSI A21.10/AWWA C104 and shall be coated inside and out with a bituminous coating.

PVC pressure pipe shall be designed to carry potable water at pressures (including surge) up to the maximum class rating. Materials from which the pipe, couplings and fittings are manufactured shall conform to ASTM D1784, Type 1, Grade 1, two thousand (2,000) p.s.i design stress. The minimum wall thickness for the pipe shall be C900 (Class 200). Two (2) inch PVC pressure pipe shall have a minimum wall thickness for the pipe shall be DR 17 (Class 250) or Schedule 40 (Class 270).

All PVC pipe shall conform to the latest revisions of ASTM D2241, Department of Commerce PS22-70 (SDR-PR) pressure rated pipe and National Sanitation Foundation Testing Laboratories (NSF). Pipe ends shall be tapered to accept gasketed couplings. Flexible elastomeric gaskets, meeting the requirements of ASTM F477, shall be synthetic rubber.

The couplings and fittings shall accommodate the pipe for which they are used. The minimum pressure ratings shall be two hundred thirty-five (235) psi for couplings and two hundred fifty (250) psi for the fittings.

Acceptance Testing.

All costs associated with acceptance testing of the water system shall be the responsibility of the developer.

Pressure tests.

(1)

The contractor shall furnish all pumps, piping, labor and other materials and services necessary to bring the piping up to the specified test pressure.

(2)

All pipes shall be pressure tested. Pipes which will be pressurized under normal operating conditions shall conform to the requirements of the hydrostatic pressure test. All other piping shall meet the requirements of the air leakage test.

(3)

Pipe in the sections to be tested shall be backfilled or center loaded, with thrust blocks installed and completely backfilled. Interior pipe supports and restraint systems shall be completely installed prior to testing.

Hydrostatic pressure test.

(1)

Test connections shall be made and the pipe filled with water. Unless otherwise specified, a pressure of not less than one and one-half (1.5) times the normal operating pressure (for the lowest point on the pipe line) but not less than one hundred fifty (150) pounds per square inch (psi) or not more than the rated working pressure for the pipe shall be used for testing.

(2)

After air removal, water shall be pumped in to bring the pipe to the specified pressure. After two (2) hours, additional water shall be drawn from a container of known volume. The amount of water required to return the system to the specified pressure shall not exceed the amount determined by the following formula:

	Q = SD(P)^½/133000,
Where	Q	=	Total allowable leakage in two hours, gallons.
	S	=	Length of section tested, feet.
	D	=	Nominal pipe diameter, inches.
	P	=	Test pressure, psi.

(3)

All exposed pipe, fittings, valves, hydrants and joints shall be inspected and all evidence of moisture appearing on the surface of the ground during the test shall be investigated by the contractor by excavation where the pipe has been covered with backfill. Should the leakage test results exceed allowable leakage, the test pressure shall be maintained for an additional period of time as directed by the engineer to facilitate location of leaks.

(4)

All pipe, fittings, valves, pipe joints, hydrants and other materials which are found to be defective when the pipeline is tested shall be removed from the line immediately and replaced with new and acceptable material by and at the expense of the contractor. The pressure test shall be repeated after repairing leaks and other defective work until the pipeline installation conforms to specified requirements and is accepted by the engineer.

Fire Hydrants.

Fire hydrants shall conform to AWWA C502 and shall be Mueller "Centurion" A423.

Hydrants shall be traffic models with breakaway flanges and shall have one (1) four and one-half (4½) inch pumper nozzle and two (2) two and one-half (2½) inch nozzles. All hydrants shall be furnished with auxiliary gate valves.

Hydrants should be placed at or near street intersections and at intermediate points when block lengths become long. Under no circumstances shall the spacing of fire hydrants exceed five hundred (500) feet in residential areas or three hundred (300) feet in commercial areas.

Fire hydrant installations shall conform to the standard drawings.

Clean and disinfect potable water distribution piping as follows:

(1)

Purge all new water distribution piping systems and parts of existing systems that have been altered, extended or repaired prior to use.

(2)

Use the purging and disinfecting procedure prescribed by the authority having jurisdiction or, in case a method is not prescribed by that authority, use the procedure described in AWWA C651 or as described below:

(a)

Fill the system or part thereof with a water/chlorine solution containing at least fifty (50) parts per million of chlorine. Isolate (valve off) the system or part thereof and allow to stand for twenty-four (24) hours.

(b)

Drain the system or part thereof of the previous solution and refill with a water/chlorine solution containing at least two hundred (200) parts per million of chlorine and isolate and allow to stand for three (3) hours.

(c)

Following the allowed standing time, flush the system with clean, potable water until chlorine does not remain in the water coming from the system.

(d)

Submit water samples in sterile bottles to the authority having jurisdiction. Repeat the procedure if the biological examination made by the authority shows evidence of contamination.

Line Valves. Gate valves shall be of the resilient-seated configuration and shall conform to the applicable requirements of AWWA C509.

Resilient-seat gate valves shall be American-80 "CRS" or Mueller A-2370-20 or approved equal.

Gate valves shall be used in all water mains twelve (12) inches in diameter and smaller.

Butterfly valves shall conform to AWWA C504 and shall be American (Class 150B), Mueller "Line Seal III" or approved equal. Butterfly valves shall be used in mains larger than twelve (12) inches in diameter or where otherwise approved by the City's consulting engineer.

Valves shall be placed in all straight runs of pipe at intervals not to exceed eight hundred (800) feet. Where two (2) lines intersect, a valve should be placed in each pipe on each side of the intersection. Valves should be so placed that any pipe two (2) blocks long can be cut out of the general circulation without interrupting service in the rest of the system.

Extension stems shall be provided for buried valves when the operating nut is more than three (3) feet below finished grade. Each extension stem for a buried valve shall extend to within three (3) feet of the ground surface, shall be provided with spacers that will center the stem in the valve box and shall be equipped with a wrench nut.

Tapping Sleeves And Valves. Tapping sleeves and valves shall be used where required to connect to existing in-service mains.

The valves shall be two hundred (200) p.s.i, resilient-seated, cast iron body, non-rising stem gate valves conforming with all applicable requirements of AWWA C509 and shall be Mueller "No. A2307-16" or an approved equal. Each tapping valve shall be provided with a flanged inlet end designed, faced and drilled for connection to the outlet end of the tapping sleeve. The outlet end of the tapping valve shall be provided with a tapping flange for attachment of a standard drilling machine and also with a mechanical joint-type bell end for connection of the branch main.

Tapping sleeves shall be of the flanged-outlet type designed for attachment to the flanged inlet end of the tapping valve and shall be provided with mechanical joint ends at each end of the run and shall be Mueller "No. H-615" for ductile iron pipe or approved equal.

Connections To Existing Water Mains. Connections to existing water mains shall be made in such a manner as to provide the least amount of interruption to water service. In the event closing of valves to make a connection will affect a customer who cannot be without service, provisions shall be made on the plans for a temporary service.

Provisions For Future Extensions Of Water Maims.

At the termination of all water mains or at locations as specified by the City's consulting engineer, a dead-end assembly in accordance with the specifications of the City of Hermann shall be provided to allow for future water main extensions.

Flushing assemblies shall be used at locations as required to provide for thorough flushing of all water mains in the project area. Whenever practical, water mains five hundred (500) feet and longer shall be provided with a fire hydrant for flushing.

Thrust Blocking. Reaction blocking of adequate size shall be provided at all tees, elbows and bends to resist all resultant thrusts due to hydrostatic pressure. All blocking shall conform to the standard drawings.

Highway And Railroad Crossings. All crossings of highways or railroads shall be made by boring or tunneling. The work shall be in conformity with all requirements and regulations and be under the control of the authority owning or having jurisdiction over and control of the right-of-way in each case.

Street Crossings. Open cutting of streets shall be allowed only where permitted by the City's consulting engineer. At locations where open cutting is not permitted, the crossing shall be made by boring or tunneling. Crossings made by boring or tunneling shall require a casing pipe unless otherwise approved by the City's consulting engineer. All work and materials shall be in conformity with all requirements of the technical specifications of the City of Hermann. The diameter and length of the casing pipe to be used shall be as determined by the City's consulting engineer.

Fire Flow Requirements. Public improvement plans for water line projects serving development sites other than single-family or duplex subdivisions shall be reviewed for fire protection sufficiency. The City Fire Chief shall determine the amount of water that is required for fire protection based on I.S.O. guidelines for the proposed type of structures to be built within the development. The design engineer shall obtain the flow requirement and then determine if the existing operating conditions will allow for the plan improvement. Calculations verifying that the required flows can be met shall accompany the drawings when submitted for approval.