Chapter 4 PIPE LAYING

CHAPTER 4
PIPE LAYING

Section 3401. (previously 3039). Method.

The pipe shall be laid upgrade without break, from structure to structure, with the bell end upgrade. Each pipe shall be laid in the proper position on a firm bed, and shall have uniform support and bearing the entire length of the barrel. Each bell shall be clean before the spigot of the succeeding pipe is inserted. A bell hole shall be dug at the end of each pipe to accommodate the bell and facilitate the making of the joint.

(Added, §1, Ord. 35, 04-06-59)

(Amended, §1, Ord. 162, 07-01-14)

(Amended, §1, Ord. 169, 05-03-16)

Section 3402. (previously 3040). Grade.

The pipe shall be laid at uniform grade, in a straight alignment and in conformity to the prescribed lines and grades. The subgrade for the pipe shall uniformly support the pipe across all spans. A laser leveling device can be used for establishing grade. Cut sheets or other acceptable methods of confirming grade and slope are required on any public sanitary sewer construction.

(Added, §1, Ord. 35, 04-06-59)

(Amended, §10, Ord. 60, 11-06-78)

(Amended, §1, Ord. 133, 01-07-03)

(Amended, §1, Ord. 138, 07-01-05)

(Amended §1, Ord. 150, 07-01-09)

(Amended, §1, Ord. 162, 07-01-14)

(Amended, §1, Ord. 169, 05-03-16)

(Amended, §1, Ord. 183, 09-03-19)

Section 3403. (previously 3041). Ends Protected.

At the close of each day’s work on all sewers that are not in service, and at such other times when pipe is not being laid, the end of the pipe shall be protected with a close-fitting stopper. Whenever the work ceases for any reason or when the pipe is constructed with end not joined to an existing pipe or structure, it shall be closed by a cap or stopper, tightly sealed in place.

(Added, §1, Ord. 35, 04-06-59)

(Amended §1, Ord. 150, 07-01-09)

(Amended, §1, Ord. 162, 07-01-14)

(Amended, §1, Ord. 169, 05-03-16)

Section 3404. (previously 3042). Joints.

The joint shall be made in accordance with the manufacturer’s specifications for the type pipe and joint material being used. All pipe and jointing material to be used shall be approved by an authorized District representative or Inspector.

(Added, §1, Ord. 35, 04-06-59)

(Amended, §1, Ord. 52, 08-05-75)

(Amended §1, Ord. 150, 07-01-09)

(Amended, §1, Ord. 162, 07-01-14)

(Amended, §1, Ord. 169, 05-03-16)

Section 3405. (previously 3043). Mixing of Pipe Types.

No mixing of the same type of pipe produced by different manufacturers shall be permitted. Mixing of pipe type will be permitted for repair sections greater than five feet in length only on building sewers in accordance with general provisions.

(Added, §1, Ord. 35, 04-06-59)

(Amended, §1, Ord. 138, 07-01-05)

(Amended, §1, Ord. 162, 07-01-14)

(Amended, §1, Ord. 169, 05-03-16)

Section 3406. (previously 3044). Alternate Types of Pipe.

Alternate types of pipe may be permitted when special conditions warrant and only then when first approved by the General Manager or authorized District representative.

(Added, §1, Ord. 35, 04-06-59)

(Amended, §1, Ord. 52, 08-05-75)

(Amended §1, Ord. 150, 07-01-09)

(Amended, §1, Ord. 162, 07-01-14)

(Amended, §1, Ord. 169, 05-03-16)

Section 3407. (previously 3045). Temporary Trench Crossings.

At street crossings or where existing driveways or walks occur on a street, the contractor shall make provision for trench crossings at these points, either by means of backfills or temporary bridges, as the Inspector may direct.

(Added §1, Ord. 150, 07-01-09)

(Amended, §1, Ord. 162, 07-01-14)

(Amended, §1, Ord. 169, 05-03-16)

Section 3408. (previously 3051). Bedding and Backfill.

(a) Except for required foundation material (in an envelope of geotextile fabric) coarse bedding material being placed in over-excavated areas, where water or soft ground is present, backfill shall not be placed until after all water is removed from the excavation.

(b) Pipe zone bedding and backfill operations shall be performed in accordance with the following requirements:

(1) Pipe embedment and backfill material (Class 2 aggregate base) shall be placed and properly compacted in the pipe zone. The pipe zone is defined as that portion of the vertical trench cross-section lying between a plane four to six inches below the bottom surface of the pipe, i.e., the trench subgrade, and a plane at a point 12 inches above the top outside surface of the pipe. The subzones of the pipe zone are defined as follows:

(A) “Bedding” is that portion of the pipe zone between the bottom of the trench or the top of required foundation material and the lowest point on the outside surface of the pipe barrel excepting bells;

(B) “Haunching” is that portion of the pipe zone between the top of the bedding and the horizontal centerline of the pipe;

(C) “Shading” is that portion of the pipe zone between the top of the haunching and a horizontal plane 12 inches above the highest point on the outside surface of the pipe barrel excepting bells.

(2) Controlled low strength material (CLSM) shall be provided in lieu of Type I bedding and backfill material where indicated on the plans. Contractor shall provide a method to prevent pipe from floating during backfill. (The remaining portions of the trench shall be backfilled as specified elsewhere in this section.)

(3) After compacting the bedding, the contractor shall perform a final trim using a stringline for establishing grade, such that each pipe section when laid will be continually in contact with the bedding along the bottom of the pipe. The contractor shall provide bell holes at each pipe joint.

(4) Backfill in trenches shall be placed uniformly on each side of the pipe to prevent displacement. The contractor shall exercise care to prevent damage to the pipeline coating, cathodic bonds, or the pipe itself during the installation and backfill operations. The contractor shall hand shovel slice the bedding along the sides of the pipe in order to ensure filling any voids under the pipe haunches.

(c) A colored detectable metallic foil core plastic tape, at least three inches in width, shall be placed on top of the pipe zone backfill wherever sewers are installed. The tape shall have printed on it the words “Caution: Sewer Buried Below.” The warning tape shall be utilized for all pipes (mains and laterals). This shall be required for all new sewer mainlines and shall not apply to building sewers.

(d) After the pipe zone backfill has been placed as specified above, and after all excess water has completely drained from the trench, backfilling of the trench zone may proceed. The trench zone is defined as that portion of the trench excavation between the top of the shading and the ground surface in unpaved areas, and the horizontal plane at lowest point of the pavement structural section in paved areas.

(e) “Final backfill” is that portion of the trench zone in paved areas between the top of the trench backfill and the lowest point of the pavement structural section.

(f) Backfill materials shall be placed and spread evenly in layers. The backfill layers shall be evenly spread so that each layer shall not exceed eight inches in uncompacted thickness. Backfill layers greater than eight inches but no more than 24 inches may be used after the contractor demonstrates by compaction testing as specified below, that required compaction levels will be achieved.

(g) During spreading, each layer shall be thoroughly mixed as necessary to promote uniformity of material in each layer. Pipe zone backfill materials shall be manually spread around the pipe so that when compacted, the pipe zone backfill will provide uniform bearing and side support.

(h) Where the backfill material moisture content is below the optimum moisture content, water shall be added before or during spreading until the proper moisture content is within the range where the specified compaction can be achieved.

(i) Where the backfill material moisture content is too high to permit the specified degree of compaction, the material shall be bladed, aerated or dried and/or mixed with dryer material until the moisture content is satisfactory.

(j) Whenever selection is possible, embankment material having a sand equivalent value of less than 10 shall be deposited in the lower portions of embankments and no such material shall be placed within three feet of planned finished grade.

(k) When the embankment material consists of large rocky material, or hard lumps such as hardpan or cemented gravel which cannot be broken readily, such material shall be well distributed throughout the embankment, and sufficient earth or other fine material shall be placed around the large material as it is deposited so as to fill the interstices and produce a dense compact embankment, but in no case shall any material exceed 24 inches in any dimension.

(l) Each layer of backfill material as defined herein shall be mechanically compacted to the specified percentage of maximum density. Equipment that is consistently capable of achieving the required degree of compaction shall be used and each layer shall be compacted over its entire area while the material is at the required moisture content. Compaction at the top of the pipe zone shall be done using a plate compactor.

(m) Flooding, ponding, or jetting shall not be used.

(n) Equipment weighing more than 10,000 pounds shall not be used within a horizontal distance equal to the depth of the trench. Hand operated power compaction equipment shall be used where use of heavier equipment is impractical or restricted due to weight limitations.

(o) The following compaction requirements shall be in accordance with ASTM D 1557 except for free draining materials (i.e., Coarse Bedding Material/Drain Rock/Foundation Material), which shall be in accordance with ASTM D 4253 and D 4254 for cohesionless free draining type materials. Where other public agency, utility company or encroachment permit requirements govern, the highest compaction standards shall apply.

Percent (%) Location or Use of Fill	Relative Compaction
Pipe zone backfill including bedding and over excavated foundation zone.	90
Final backfill beneath paved areas or structures.	95
Trench backfill in unpaved easement or future street areas.	90
Trench zone backfill.	90
Backfill under structures.	95
Backfill around structures under paved areas.	95
Backfill around structures in landscaped areas.	90
Embankment material.	90

(p) The contractor shall maintain the indicated trench cross-section at a minimum of 12 inches above the top of the pipe (the top of the “pipe zone”).

(q) Embankments shall be constructed as recommended by the geotechnical engineer in compacted layers of uniform thickness.

(r) At the time of compaction, the moisture content of embankment material shall be such that the relative compactions specified will be obtained and the embankment will be in a firm and stable condition. Embankment material which contains less than the required moisture content shall be watered and material which contains excessive moisture shall not be compacted until the material is dry enough to obtain the required compaction.

(s) A minimum of two inches of cold or hot mix temporary asphalt shall be placed in finished trenches and rolled to a smooth surface at the end of each day unless final paving can be completed or steel plates are used to cover trenches in paved streets.

(Added, §1, Ord. 162, 07-01-14)

(Amended, §1, Ord. 169, 05-03-16)

(Amended, §1, Ord. 183, 09-03-19)

Section 3409. (previously 3090). Preliminary Air Test.

All main sewers or building sewers may, at the District’s option, be subject to the following requirements:

Before any portion of the trench with mains and/or building sewers is backfilled, the following test may be made:

(a) The contractor shall plug all building sewers as described in Section 3403 of this Code. He shall plug the ends of the mains with plugs and brace the ends of the pipe where needed.

(b) The line shall be supplied with air at such a rate as to maintain a minimum of three pounds per square inch (three psi) pressure in the line. For this purpose the contractor shall furnish a compressor with adequate capacity and with necessary fittings adaptable to the testing apparatus, and the metering apparatus and hoses necessary for the test.

(c) Each joint, the entire surface of all pipe, and all plugs shall be checked for air leakage in the presence of the Inspector. In the event it is necessary, use a soap and water solution at the joints to locate air leakage.

(d) All material and joints found defective shall be repaired or replaced by the contractor at no expense to the District.

(e) If the line tested leaks excessively, the preliminary test must be repeated after the repairs have been made and before that portion of the line shall be backfilled and compacted.

(Added, §1, Ord. 35, 04-06-59)

(Amended, §1, Ord. 52, 08-05-75)

(Amended, §1, Ord. 150, 07-01-09)

(Amended, §1, Ord. 162, 07-01-14)

(Amended, §1, Ord. 169, 05-03-16)

(Amended, §1, Ord. 174, 11-07-17)

Section 3410. (previously 3091). Final Main Sewer Test.

After the sewer lines have been examined and repaired in accordance with Section 3409 of this Code, and after the trench has been backfilled and compacted, and before paving, the lines shall be given the following final test:

(a) The contractor shall plug all building sewers as described in Section 3403 of this Code. He shall plug the ends of the main, and if buildings have been connected, the contractor shall plug at the clean-out.

(b) The contractor shall supply the necessary metering equipment and hoses, and a compressor with adequate capacity to perform the test.

(c) The line shall be supplied with air until four psi has been reached at which time the flow to the pipe shall be shut off. The Inspector will then accurately determine the time of loss of one psi pressure in the range from four psi to three psi.

(d) The minimum test time for all pipe lengths shall be no less than the time required for 100 feet of pipe. The time loss of one psi shall be greater than the interval calculated from the following table:

Pipe Diameter (inches)	Test Time (seconds/100 ft length of pipe)
4	18
6	42
8	72
10	90
12	108
15	126
18	144
21	180
24	216
27	252

If the time loss is less than required, the contractor shall make such repairs as are necessary to eliminate the excessive leakage. The test shall be repeated after the repairs are made. The line shall not be accepted until this test is passed.

(e) Grouting or other methods of internally or externally sealing defective or leaking joints or pipe shall not be permitted. The sewer system must pass the air test as installed or as repaired, without recourse to sealing.

(f) Contractor shall arrange for internal television inspection of sewer mains in conjunction with the final air test. Television inspection system shall at a minimum be color, pan and tilt and recordable. Television inspection shall be observed by the District Inspection Staff while in progress, on the closed-circuit monitor and an electronic copy of the video inspection records on DVD to be given to District’s Inspector. Bell-and-spigot joints shall show no offset; “band-seal” joints shall show not more than one-eighth-inch offset in any direction. Joints exceeding these limitations, and any other defects discovered, shall be repaired by excavation and replacement.

(g) The District may at any time within the one-year guarantee period as described in Section 3106 of this Code repeat the tests described in this Section to determine the condition of the sewer, or at any time prior to acceptance thereof by the District Board.

(h) The contractor may request a test as set forth in this Section to determine the condition of the sewer at any time during the progress of construction. Such tests shall not constitute the final test.

(Added, §1, Ord. 35, 04-06-59)

(Amended, §1, Ord. 52, 08-05-75)

(Amended, §1, Ord. 64, 02-10-81)

(Amended, §1, Ord. 80, 03-10-87)

(Amended, §2, Ord. 97, 09-01-92)

(Amended, §1, Ord. 133, 01-07-03)

(Amended, §1, Ord. 150, 07-01-09)

(Amended, §1, Ord. 162, 07-01-14)

(Amended, §1, Ord. 169, 05-03-16)

(Amended, §1, Ord. 174, 11-07-17)

(Amended, §1, Ord. 183, 09-03-19)

Section 3411. (previously 3068, 3092). Building Sewer Test.

All building sewers, wyes, tees and fittings are subject to the same requirements and tests as main lines. Before any portion of the building sewer trench is backfilled, the District shall be notified of completion and the contractor shall request a test as described in Section 3409 of this Code or the following manner:

(a) If a test wye has been installed in the building sewer as near the main as practical it shall be plugged with a double plug.

(b) The complete building sewer including the connection to the building shall be filled with air pressure to four psi or filled with water. Any leak shall be repaired before the sewer is backfilled.

(Added, §1, Ord. 35, 04-06-59)

(Amended, §1, Ord. 52, 08-05-75)

(Amended, §4, Ord. 119, 06-03-98)

(Amended, §1, Ord. 138, 07-01-05)

(Amended, §1, Ord. 150, 07-01-09)

(Amended, §1, Ord. 162, 07-01-14)

(Amended, §1, Ord. 169, 05-03-16)

(Amended, §1, Ord. 174, 11-07-17)

Section 3412. (previously 3093). Cleaning Sewer Main Lines.

After all backfilling operations are completed and prior to video inspection of the sewer, the contractor shall flush and clean all newly constructed sanitary pipes in the following manner:

A screen basket with openings no larger than one-half inch shall be placed in the channel of the lower manhole and secured in the bottom step. The contractor shall flush the new sewer main with a high pressure cleaning nozzle and pull all debris downstream to be captured in the basket. This process shall be repeated until the line is clean and approved by the Inspector.

(Added, §1, Ord. 35, 04-06-59)

(Amended, §1, Ord. 52, 08-05-75)

(Amended, §1, Ord. 150, 07-01-09)

(Amended, §1, Ord. 162, 07-01-14)

(Amended, §1, Ord. 169, 05-03-16)

(Amended, §1, Ord. 174, 11-07-17)

Section 3413. Public Sewer Replacement via Pipe Bursting.

(a) Sewer mains that will be replaced via pipe bursting shall be inspected using CCTV with pan and tilt capabilities prior to construction. The sewer mains shall be free of normal flow and debris during this inspection. All laterals and sags in the sewer mains shall be marked in the field prior to commencing pipe bursting. A District Inspector must be present during the preconstruction CCTV inspection and a copy of the CCTV inspection shall be provided to the Inspector.

(b) A bypass plan shall be submitted for approval to the District prior to commencing pipe bursting work.

(c) Building sewer services shall not be disconnected for a time period longer than six hours. Notification of disrupted service shall be provided to all affected residents.

(d) HDPE sewer mains shall be air tested after pipe bursting operation is complete, prior to reconnection of lateral services.

(e) Finished manhole connections, including final concrete and grout repair work, shall not be completed for at least 24 hours after pipe bursting work has been completed.

(f) Building sewer services shall be reconnected utilizing electrofusion couplings as approved by the District.

(g) Post construction CCTV inspection shall be done with no wastewater flow in the line and with a District Inspector present. A target shall be used to measure any sags in the line and the contractor shall be responsible for repairing all sags that are outside of the District’s allowed tolerances. The District Inspector shall be given a copy of the postconstruction CCTV inspection video.

(h) As-built record drawings shall be provided to the District upon pipeline acceptance.

(Added, §1, Ord. 174, 11-07-17)