Building construction and fire prevention — See Ch. 56.
Sewers — See Ch. 140.
Subdivision of land — See Ch. 150.
Water — See Ch. 169.
Zoning — See Ch. 175.
§ A182-1Duties of contractor.
§ A182-2Water pipe and fittings.
§ A182-3Laying pipe.
§ A182-4Thrust blocks.
§ A182-5Water main and sewer crossings and separation.
§ A182-6Service connection and taps.
§ A182-7Inspection and testing.
§ A182-8Disinfection of mains.
The contractor shall supply all labor, tools, materials and equipment to construct, test and disinfect the water mains as described in these specifications and the accompanying drawings.
All pipe shall conform to the sizes shown on the drawings
Ductile iron pipe. Ductile iron pipe shall be Class 52 and shall conform to ANSI Standard A21.51 (AWWA C-151). Each pipe shall be tested at a hydrostatic pressure of not less than 500 pounds per square inch as detailed in ANSI Standard A 21.51. Cement linings shall be in accordance with ANSI A21.4 (AWWA C-104). Joints employing a single elongated grooved gasket to effect the joint seal, such as United States Pipe and Foundry "Tyton" type or approved equal, will be acceptable. Bituminous coating inside and outside of pipe shall conform to ANSI A21.8 (AWWA C-108).
Cast-iron fittings. Cast-iron fittings shall conform to the ANSI Specifications 21.10 or AWWA Standard C-110. The fittings shall be cement lined in accordance with ANSI Specification A21.4 (AWWA C-104). Joints shall be mechanical joints unless specified otherwise and shall conform to the applicable requirements of ANSI A21.11 (AWWA C-111).
Gate valves and valve boxes. All gate valves shall meet the requirements of AWWA Standards C-509. They shall be iron body, bronze mounted, resilient seat, wedge disc, mechanical joint gate valves with nonrising stems, Oring type packing and standard two-inch operating nuts. All gates shall open to the left, shall be of Mueller or approved equal, proportioned for working pressures of 200 pounds per square inch (psi) hydrostatically tested at 400 pounds per square inch shell. Each valve shall be provided with a cast-iron telescoping valve box and cover installed by the contractor. The contractor shall provide anchor blocks and/or clamps as directed by the Engineer for the gate valves. The valve boxes shall be five-and-one-fourth-inch diameter, two- or three-piece, sliding type, Mueller figure H10364, or approved equal. The valve boxes shall be adequate for the trench depth so that when set on the valve, the cover is level with the pavement or the completed surrounding ground, whichever is applicable. The valve box cover shall have the word "WATER" cast in top.
Tapping sleeves and valves. Tapping sleeves shall be Mueller H-615 or approved equal and tapping valves shall be Mueller H-667 or approved equal. Joints shall be mechanical joint.
All hydrants shall conform to AWWA Specification C-502 with a working pressure of 150 pounds per square inch and shall be of a break-flange traffic construction type Mueller Centurion. The hydrant shall have the operating nut pentagon shaped, measuring 1 1/2 inches from the point to flat, opening counterclockwise. Two two-and-one-half-inch hose and one four-and-one-half-inch pumper nozzle shall have the National Standard threads and shall be covered with nut-type caps and chains. Size of nuts shall be the same as the operating nut.
The hydrant shall have the bottom valve size at least 5 1/4 inch, with bronze seat ring and shall have a minimum of six-inch inlet opening with mechanical joint connection for a pipe to an auxiliary gate valve. The auxiliary gate valve shall be at least six inches in size with a valve box and cover.
The depth of bury for hydrant shall be five feet unless greater depth is needed due to the ground elevation or the depth of the pipe. Graded gravel shall be placed around the lower part of the hydrant for drainage purposes. The hydrant shall be installed as specified in Section 3.7 of AWWA Standard C-600 and/or as shown in the hydrant details of other applicable specifications. The hydrant shall be painted bright red or other colors as may be specified by the owner. Hydrants shall be UL or FM approved, where required.
All cast-iron pipes shall be laid in accordance with AWWA Standard C-600. All pipes, fittings and valves shall be carefully handled to avoid damage and, while they are suspended over the trench, before lowering, they shall be rung and inspected for defects. Before the pipe is laid, all lumps, blisters, excess coal tar, dirt, oil, grease and moisture shall be removed from inside the pipe. After pipe is laid, care shall be taken to avoid the entrance of dirt or water from the trench by use of tight bulkheads. The handling of material shall conform to Section 2.2 of AWWA Standard C-600.
The pipe shall be laid to conform to lines and grades shown on the plans or as directed by the Engineer. The pipe shall have a minimum cover of four feet six inches unless noted otherwise on the drawings.
Excavation and preparation of the trench shall be in accordance with AWWA C-600, as applicable. The bottom of the trench shall be carefully graded and bell holes cut to receive the bell of the pipe.
After laying and inspecting the pipe, each length shall be carefully backfilled by placing approved material free from stone around the pipe. Backfill shall be thoroughly compacted and tamped in six-inch layers so as to securely hold the pipe in place, but not tamped to cause movement of the pipe. This careful placing shall continue until a minimum of one foot of earth has been placed and tamped over the top of the pipe. From one foot above the pipe to the grade shown on the drawings
Concrete reaction or thrust blocks and/or clamps shall be placed behind all bends, tees, caps and plugs or other fittings and as directed by the Engineer. Concrete shall have a twenty-eight-day compressive strength of 2,500 pounds per square inch. Excavation for the same shall be carried out by hand at such locations to provide a good bearing against undisturbed materials within a short distance from the pipe or fittings. The thrust blocks shall be of the dimensions shown on the drawings
Wherever possible, separate water and sewer lines at least 10 feet horizontally. Where not possible, separate as much as possible; lay in a separate trench and, if in the same trench, keep water main as far as possible from sewer main and at least 18 inches above sewer.
At street intersection or at other locations where water and sewer lines must cross, place crown of sewers 18 inches below invert of water line, if possible. If less than 18 inches lower or if water line must pass under sewer, special care must be taken as follows:
One full length of water main shall be centered on sewer crossing so joints are equidistant and as far as possible from the sewer. The sewer shall be constructed of materials and with joints that are equivalent to water main standards of construction and shall be pressure tested to assure watertightness prior to backfilling. The sewer so constructed shall be at least 44 feet or three full lengths of pipe, whichever is greater. The pressure test of this portion of sewer shall be done in accordance with AWWA Standard C-600, Section 13.7, at not less than 20 pounds per square inch and maximum leakage allowance at 20 pounds per square inch shall be 8 1/2 gallons per day per mile per inch nominal diameter of pipe.
Water line passing under sewer shall, in addition, be protected by providing a vertical separation of at least 18 inches between the bottom of the sewer and the top of the water main. Provide adequate support for sewer to eliminate any possibility of settling of the sewer line.
A three-fourths inch or one-inch tap shall be left or made for each house requiring a new service. Taps may be made by means of a tapped coupling left at proper location or by cutting with an approved tapping machine or by use of service saddles approved by Engineer. Taps shall be of the type thread to accept a standard corporation stop as supplied by Mueller or equal. All taps one inch or larger in six-inch cast-iron pipe, or larger than one-inch in eight-inch cast-iron pipe, will require tapping saddle.
Soft copper tubing, type K in three-fourths-inch or one-inch diameter shall be laid from the tap to the location of a new curb box for each house. Couplings or fittings between corporation stop and curb cock shall be brass or bronze conductive compression connection type. Provide a bend or gooseneck in the tubing, as shown in the service connection detail, for flexibility. Curb stop and curb box is to be left at the end of each service for the property owner to connect to.
Curb stops shall be Mueller H 15209 or approved equal. The curb box shall be Mueller H 10304 or approved equal. A curb box sleeve, Mueller H 10342 or approved equal shall be used where curb box is in sidewalk or paved area.
The contractor shall supply all necessary materials and equipment to test the piping as described below, including pump, piping, valves and labor. The Engineer will supply the test gauge or else calibrate the contractor's gauge before and after the tests. All pressure tests must be done in the Engineer's presence under his direction. The testing of water mains shall be done in accordance with AWWA Standard C-600.
Two tests are required.
The first shall be a hydrostatic pressure test only. This shall be done when a section of line has been completed and concrete thrust blocks have set up sufficiently. The line shall be partially backfilled or braced against movement during the test. All air must be bled out of the section to be tested. If necessary, the contractor shall install corporation stops at the high points, for blowoffs. The hydrostatic test shall be of at least two hours' duration. Test pressure shall be as indicated by the Engineer and, in general, shall be done 1 1/2 times the actual working pressure applied at the lowest point of the section to be tested. A correction shall be made for the difference in elevation between this point and the test gauge. The pressure in the line shall not vary by more than ± five pounds per square inch for the duration of the test. With the required pressure on the line, the entire run shall be examined for evidence of leakage. Any leaks discovered shall be corrected and the test repeated.
A leakage test of two hours' duration shall be conducted concurrently with a pressure test. No pipe installation will be accepted unless and until the leakage is less than the amounts allowed in AWWA Specifications C-600, Section 4.2, Table 6. Allowable leakage is determined by the following formula, where L is leakage in gallons per hour, S is the length of pipe tested in feet, D is the nominal diameter of the pipe in inches and P is the average test pressure during the test in pounds per square inch. Allowable leakage is approximately 11.65 United States gallons per 24 hours per mile per inch nominal diameter of pipe at a pressure of 150 pounds per square inch.
|L =||SD√P 133,200|
When testing against closed metal-seated valves, an additional leakage per closed valve of 0.0078 gallons per hour per inch of nominal valve size shall be allowed.
All visible leaks are to be repaired regardless of the amount of leakage.
All new work shall be disinfected by the contractor. Disinfection shall be performed in an approved manner in accordance with the American Water Works Association's Standard for Disinfecting Water Mains, Designation C-651, except that the tablet method described in Section 5.1 of C-651 shall not be used.
Preventive measures during construction.
Keeping pipe clean and dry. Precautions shall be taken to protect pipe interiors, fittings and valves against contamination. Pipe delivered for construction shall be strung so as to minimize entrance of foreign material. When pipe laying is not in progress, as, for example, at the close of the day's work, all openings in the pipeline shall be closed by watertight plugs. Joints of all pipe in the trench shall be completed before work is stopped. If water accumulates in the trench, the plugs shall remain in place until the trench is dry.
If dirt that, in the opinion of the Engineer or job superintendent, will not be removed by the flushing operation enters the pipe, the interior of the pipe shall be cleaned and swabbed as necessary, with a 5% hypochlorite disinfecting solution.
Preliminary flushing. The main shall be flushed prior to disinfection. The flushing velocity shall not be less than 2 1/2 feet per second. The rate of flow required to produce this velocity in various diameters is shown in Table I. No site for flushing should be chosen unless it has been determined that drainage is adequate.
|TABLE I Required Openings to Flush Pipelines* (40 pounds per square inch residual pressure)|
|Pipe Size (inches)||Flow Required to Produce 2.5 Feet per Second Velocity (gallons per minute)||Orifice Size (inches)||Hydrant Outlet Number||Nozzles Size (inches)|
|6||220||1 3/8||1||2 1/2|
|8||390||1 7/8||1||2 1/2|
|10||610||2 5/16||1||2 1/2|
|12||880||2 13/16||1||2 1/2|
|14||1,200||3 1/4||2||2 1/2|
|16||1,565||3 5/8||2||2 1/2|
|18||1,980||4 3/16||2||2 1/2|
|*||With 40 pounds per square inch residual pressure, a two-and-one-half-inch hydrant outlet nozzle will discharge approximately 1,000 gallons per minute and a four-and-one-half-inch hydrant nozzle will discharge approximately 2,500 gallons per minute.|
Form of chlorine for disinfection. The most common form of chlorine used in the disinfecting solutions is liquid chlorine (gas at atmospheric pressure), calcium hypochlorite granules and sodium hypochlorite solutions.
Liquid chlorine shall be used only when suitable equipment is available and only under the direct supervision of a person familiar with the physiological, chemical and physical properties of this element and who is properly trained and equipped to handle any emergency that may arise. Introduction of chlorine gas directly from the supply cylinder is unsafe and shall not be permitted.
The preferred equipment consists of a solution feed chlorinator in combination with a booster pump for injecting the chlorine gas — water mixture into the main to be disinfected. Direct feed chlorinators are not recommended because their use is limited to situations where the water pressure is lower than the chlorine cylinder pressure.
Calcium hypochlorite. Calcium hypochlorite contains 70% available chlorine by weight. It is either granular or tabular in form. The tablets, 6-9 to the ounce, are designed to dissolve slowly in water. A chlorine — water solution is prepared by dissolving the granules in water in the proportion requisite for the desired concentration.
Sodium hypochlorite. Sodium hypochlorite is supplied in strengths from 5.25% to 16% available chlorine. It is packaged in liquid form in glass, rubber or plastic containers ranging in size from one-quart bottles to five-gallon carboys. It may also be purchased in bulk for delivery by tank truck. The chlorine — water solution is prepared by adding hypochlorite to water. Product deterioration must be reckoned with in computing the quantity of sodium hypochlorite required for the desired concentration.
Application of solutions.
The hypochlorite solutions shall be applied to the water main with a gasoline- or electrically powered chemical feed pump designed for feeding the chlorine solutions. For small applications, the solutions may be fed with a hand pump, for example, a hydraulic test pump.
Feed lines shall be of such material and strength as to withstand safely the maximum pressures that may be created by the pumps. All connections shall be checked for tightness before the hypochlorite solution is applied to the main.
Methods of chlorine application.
Continuous feed method.
This method is suitable for general application. Water from the existing distribution system or other approved sources of supply shall be made to flow at a constant, measured rate into the newly laid pipeline. At a point not more than 10 feet downstream from the beginning of the new main, the water entering the new main shall receive a dose of chlorine, also fed at a constant, measured rate. The two rates shall be proportioned so that the chlorine concentration in the water in the pipe is maintained at a minimum of 25 milligrams per liter available chlorine. To assure that this concentration is maintained, the chlorine residual should be measured at regular intervals in accordance with the procedures described in the current edition of Standard Methods of AWWA M12 — Simplified for Water Examination.
Table II gives the amount of chlorine residual required for each 100 feet of pipe in various diameters. Solutions of 1% chlorine may be prepared with sodium hypochlorite or calcium hypochlorite. The latter solution required approximately one pound of calcium hypochlorite in 8.5 gallons of water. If liquid laundry bleach with 5.25% chlorine is used, then 4.25 gallons of water is to be mixed with one gallon of bleach to obtain 1% solution.
|TABLE II Chlorine Required to Produce 25 Milligrams per Liter Concentration in 100 Feet of Pipe|
|Pipe Size (inches)||Volume of 100-Foot Length (gallons)||100-Percent Chlorine (pound)||1-Percent Chlorine Solutions (gallon)|
During the application of the chlorine, valves shall be manipulated to prevent the treatment dosage from flowing back into the line supplying the water. Chlorine application shall not cease until the entire main is filled with the chlorine solution. The chlorinated water shall be retained in the main for at least 24 hours, during which time all valves and hydrants in the section shall be operated in order to disinfect the appurtenances. At the end of this twenty-four-hour period, the treated water shall contain no less than 10 milligrams per liter of chlorine throughout the length of the main.
Slug method. This method is suitable for use with mains of large diameter for which, because of the volumes of water involved, the continuous feed method is not practical.
Water from the existing distribution system or other approved source of supply shall be made to flow at a constant, measured rate into the newly laid pipeline. The water shall receive a dose of chlorine, also fed at a constant, measured rate. The two rates shall be proportioned so that the concentration in the water entering the pipeline is maintained at no less than 100 milligrams per liter. The chlorine shall be applied continuously and for a sufficient period to develop a solid column of slug of chlorinated water that will, as it passes along the line, expose all interior surfaces to a concentration of at least 100 milligrams per liter for at least three hours. The application shall be checked at a tap near the upstream end of the line by chlorine residual measurements made according to the procedures described above.
As the chlorinated water flows past tees and crosses, related valves and hydrants shall be operated so as to disinfect appurtenances.
Tablet method. The tablet method, as contained in American Water Works Association Standard C-651, is not acceptable to the New York State Department of Health and shall not be used.
Final flushing. After the applicable retention period, the heavily chlorinated water shall be flushed from the main until the chlorine concentration in the water leaving the main is no higher than the generally prevailing in the system, or less than one milligrams per liter. Chlorine residual determination shall be made to ascertain that the heavily chlorinated water has been removed from the pipeline.
After final flushing and before the water main is placed in service, a sample or samples shall be collected from the end of the line and tested for bacteriologic quality and shall show the absence of coliform organisms. If the number and frequency of samples is not prescribed by the public health authority having jurisdiction, at least one sample shall be collected from chlorinated supplies where a chlorine residual is maintained throughout the new main. From unchlorinated supplies, at least two samples shall be collected at least 24 hours apart. In the case of extremely long mains, it is desirable that samples be collected the length of the line as well as at its end.
Samples for bacteriologic analysis shall be collected in sterile bottles treated with sodium thiosulphate. No hose or fire hydrant shall be used in collection of samples. A suggested samples tap consists of a standard corporation cock installed in the main with a copper tube gooseneck assembly. After samples have been collected, the gooseneck assembly may be removed and retained for future use.
Repetition of procedure. If the initial disinfection fails to produce satisfactory samples, disinfection shall be repeated until satisfactory samples have been obtained. When the samples are satisfactory, the main may be placed in service.
Procedure after cutting into or repairing existing mains. The procedures outlined in this section apply primarily when mains are wholly or partially dewatered. Leaks or breaks that are repaired with clamping devices while the mains remain full of water under pressure require no disinfection.
Trench treatment. When an old line is opened, either by accident or by design, the excavation will likely be wet and badly contaminated from nearby sewers. Liberal quantities of hypochlorite applied to open trench areas will lessen the danger from such pollution. Tablets have the advantage in such a situation because they dissolve slowly and continue to release hypochlorite as water is pumped from the excavation.
Swabbing and flushing. The following procedure is considered as a minimum that may be used.
Swabbing with hypochlorite solution. The interior of all pipe and fittings used in making the repair (particularly couplings and tapping sleeves) shall be swabbed with a 1% hypochlorite solution before they are installed.
Flushing. Thorough flushing is the most practical means of removing contamination introduced during repairs. If valving and hydrant locations permit, flushing from both directions is recommended. Flushing shall be started as soon as the repairs are completed and continued until discolored water is eliminated.
Slug method. Where practicable, in addition to the procedures of swabbing and flushing, a section of main in which the break is located shall be isolated, all service connections shut off and the section flushed and chlorinated as described, except that the dose may be increased to as much as 300 milligrams per liter and the contact time reduced to as little as 1/4 hour. After chlorination, flushing shall be resumed and continued until discolored water is eliminated.
Sampling. Bacteriologic samples shall be taken after repairs to provide a record by which the effectiveness of the procedures used can be determined. If the direction of flow is unknown, samples shall be taken on each side of the main break.