6.20.490 Force main.
The force main shall be a minimum six-inch-diameter ductile iron Class 52 polyethylene or epoxy lined or high-density polyethylene (HDPE) if approved by the district and provided with a continual positive slope. Ductile iron force main shall be restrained. HDPE shall include tracer wire. There shall be no intermediate high point between the lift station and the force main discharge point, unless properly protected with sewage air and vacuum release assembly. Minimum cover over the force main shall be four feet. All pipes (gravity and pressure) entering and leaving the wet pit or dry pit shall have flexible couplings within 18 inches of the structure. Install force main location boxes as required, shown on Detail V-S4.
Discharge of the force main to the gravity sewers shall be made at a manhole with the force main penetration core drilled and the force main aligned to discharge towards the downstream pipe. The invert of the force main shall be one-tenth-foot above the invert of the downstream pipe. Channel the manhole as required.
A bypass pump connection equipped with a Cam Lock fitting and cap shall be located near the wet well in a location specified by the district. See Detail VI-LS2.
A surge valve shall be installed on the force main to discharge into a manhole or the wet well if high head conditions will occur as determined by the district.
(1) Testing Force Main.
(a) Cleaning. All force mains shall be cleaned prior to connection of force main to pumping facilities. Contractor to provide cleaning plan for district review and approval.
(b) Test Specifications. All force mains shall be tested prior to acceptance of work. All pumps, gauges, plugs, saddles, corporation stops, miscellaneous hose and piping, and measuring equipment necessary for performing the test shall be furnished, installed and operated by the developer. Feed for the pump shall be drawn from a barrel or other container wherein the actual amount of makeup water utilized can be measured periodically during the test period.
The pipeline shall be backfilled sufficiently to prevent movement of the pipe under pressure. All thrust blocks shall be in place and time allowed for the concrete to cure before testing. Where permanent blocking is not required, the developer shall furnish and install temporary blocking.
The pipeline shall be subjected to a pressure and leakage test of a minimum of 200 pounds per square inch for a period of not less than one hour. The test pressure shall be applied at the low end of the section tested.
Prior to calling for the district to witness the pressure test, the developer shall first perform a satisfactory pressure test. The allowable leakage rate per 1,000 feet of each size pipeline is as follows:
|
Pipe Size |
Allowable Leakage Gal. per Hour per 1,000 Ft. @ 200 psi |
|
6" |
0.64 |
|
8" |
0.85 |
|
10" |
1.06 |
|
12" |
1.28 |
Defective materials or workmanship, discovered as a result of the tests, shall be replaced by the developer at the developer’s expense. Whenever it is necessary to replace defective material or correct the workmanship, the tests shall be re-run at the developer’s expense until a satisfactory test is obtained.
(c) Preliminary Tests. Developer shall conduct preliminary tests and assure himself that the section to be tested is in an acceptable condition before requesting the district to witness the test.
(d) Thrust Blocks and Anchor Blocks. Fittings shall be “blocked” with poured-in-place concrete, with a firm minimum bearing against an undisturbed earth wall. Timber blocking will not be permitted. Thrust blocks shall be poured as soon as possible after setting the fittings in place to allow the concrete to “set” before applying the pressure test. The concrete thrust blocks shall be in place before beginning the pressure test. Anchor blocks shall be allowed to set sufficiently to develop the necessary bond strength between the reinforcing rods and the concrete anchor before beginning the pressure test. A Visqueen barrier shall be provided to protect glands, bolts and other miscellaneous materials required for this type of connection from the concrete. Fittings that must be blocked against an undisturbed earth wall shall be restrained with restrained joint pipe and fittings. [Res. 735 § 1, 2017.]