SECTION 104 - Alaska Department of Transportation & Public ...



SECTION626

SANITARY SEWER SYSTEM

Special Provisions

626-1.01 DESCRIPTION. Add the following: For purposes of these specifications, "Sewer Utility" shall mean City of Unalaska, Department of Public Works and Department of Public Utilities; Telephone (907) 581-1260.

The Contractor shall provide as-builts in accordance with the conditions prescribed herein.

626-3.01 CONSTRUCTION REQUIREMENTS. Delete the following:

"When sewer conduit is laid within a I 0-foot horizontal radius of an existing or a new water main, and is above or 3 feet below the water main, use cast-iron pipe."

Add the following: The force main crossing the existing bridge is a primary collector line that is required to stay in service except as noted below. Temporary shutdowns required to make connections to the existing line shall be limited to 2- hours per connection. The construction shutdowns shall be scheduled to take place during low flow periods, between the hours of I 0 PM and 6 AM. The

Sewer Utility shall be given at least 7-days notice prior to executing a shutdown so they can be present to shut down pumping facilities and provide temporary storage during the interruption. The Contractor is responsible to purge the existing line of sewage prior to making the connection and to plug the ends to prevent sewage spills during construction.

Give at least 24-hours notice to the Sewer Utility and impacted residents before interrupting sewer service to any area. Restore disrupted sewer service as soon as possible, or make temporary services using hoses or other suitable methods.

If operations cause service interruptions in excess of those allowed for the scheduled shutdowns, the Contractor is responsible for all damages.

Sewer lines shall be laid to the lines and grades shown on the Plans plus or minus

0.03-feet. However, no flat or reverse grades will be permitted.

At a sufficient distance from encountering a known obstacle, the Contractor shall expose and verizy the exact location and elevation of the obstacle so that

. alignment and/or grade of the new sewer can be suitably adjusted. Extra costs incurred by the Contractor due to inadequate verification of known obstacles shall be at his or her expense.

All adjustments to line and grade shall be done by carefully excavating trench bottom or sidewall earthen material or filling with suitable compacted earth under the body of the pipe.

The Contractor shall have standard survey instruments such as a laser or a transit and level for transferring alignment and grades from the offset hubs. The

Contractor shall employ a person who is qualified to use such standard survey instruments to the satisfaction ofthe Engineer, and that person shall have the

responsibility for maintaining pipe line and grade. Both line and grade shall be checked and recorded in a field survey book for each piece of pipe and

appurtenance laid. The Contractor shall record actual line and grade on as-built drawings, and, upon request, shall furnish to the Engineer a copy of the line and grade notes for the newly installed pipe and appurtenances.

Ductile iron pipe spigots shall be inserted the proper length into bells as recommended by the pipe manufacturer. Bell and spigot gaskets shall be properly lubricated with a non-toxic lubricant approved by the pipe manufacturer. Bells shall be located on the downstream side of the pipe joint.

Provide green 4-mil thick by 6-inch wide polyethylene underground warning tape with the words "Caution- Buried Sewer Line" 6-inches above the top of the buried pipe.

Polyethylene encasement shall be installed on ductile iron sewer line. Polyethylene encasement shall be installed in strict accordance with the methods described in the most current editions of AWWA C105/ANSI A2l.J and the Ductile Iron Research Associations publication "A Guide to the Installation of Ductile Iron Pipe".

Steel pipe shall be welded per latest AWS D1.1 by welders qualified per the

American Welding Society for the type and position of the welds welded. Pipe

joints shall be filled full depth to match the pipe being welded. All filler metal (

shall have a carbon content closely matching the base metal (maximum 0.20%).

All SMAW electrodes shall be properly conditioned low hydrogen. Submit welder qualifications and welding procedures to the Engineer for approval.

Except where noted otherwise, as directed by the Engineer, and provided that they do not interfere with other work, the Contractor may abandon in-place existing sewer lines that are being replaced by new sewer lines. Existing lines scheduled

to be abandoned in place shall be flushed, cleaned, and plugged in a manner meeting Alaska Department of Environmental Conservation standards.

Do not lower the sanitary sewer line as shown on the drawings without potholing to confirm the depth and then the obtaining approval to proceed from the Engineer.

626-3.02 TESTING. Delete the entire subsection and substitute the following: General: The Contractor shall clean and flush all sanitary sewer pipe installed

prior to testing and final inspection. With the Engineer present, test the sewer for

grade, alignment, and leakage. Grade and alignment must conform to staking with no deviation allowed that would inhibit flow. No flow test will be required for lowering the sewer line.

1. Pipe Pressure Test: Within one day after the pipe is determined to be

clean, and the pipe is backfilled and compacted in place except as required

for plugged ends, the pipe shall be pressure tested for leakage.

Hydrostatic Testing: All newly installed piping requires testing. All tests shall be witnessed by a representative of the Owner. The Contractor shall provide all necessary equipment, labor, materials, supplies, and assistance necessary to complete the test. Remove all air from the lines prior to pressure tests. Vent air from all high parts of the system while filling. Plug ends ofline to be tested. If permanent air vents are not installed as part of this contract, the Contractor shall, at his expense, install

corporation stops at such points so the air can be expelled as the line is slowly filled with water. All hydrostatic testing shall be performed through test copper. Pressure test ductile iron pipe at 50 psi for two

hours. After the required test pressure has been reached, the pumping will be terminated. If the pressure remains constant for 30-minutes without the aid of a pump, the line will not be subjected to any future hydrostatic tests. Leakage on ductile iron pipe must be less than the calculated value

L= ND(P)05

7,400

Where:

L = allowable leakage in gallons per hour

N =summation of mechanical and push on joints in length of pipe being tested

D = diameter of pipe in inches.

P = test pressure in pounds per square inch

The duration of each leakage test shall be two (2) hours, and during the tests the main shall be subjected to the constant test pressure as defined above. The test pump shall be valved to ensure that constant test pressure is maintained throughout the test and all excess water returned to the supply tank.

If the pressure decreases below the required test pressure during the two (2) hour period, the proceding portion of that test will be declared void. Cracked or defective pipe, gaskets, joints, or fittings discovered as a consequence of the hydrostatic tests shall be removed and replaced with sound material at the Contractor's expense. The test shall then be repeated until the results are satisfactory. A report with dates, times, procedures, witnesses, and other relevant information documenting performance of the tests shall be provided to the Engineer.

If the installation fails to meet test requirements, the Contractor shall determine at his own expense the source or sources ofleakage, and he shall repair or replace the source of the leakage in a method approved by the Engineer.

Welded steel pipe shall be hydostatically pressure tested at 150 psi for a 2- hour duration after the initial test pressure has stabilized. No pressure loss or leakage shall be allowed. If pressure loss is observed, the leak shall be

located and repaired and the test shall be repeated until no pressure loss is observed.

2. Welded Pipe: Perform all welding and Nondestructive Examination (NDE) to meet AWS Dl.l. Pipes shall be joined with complete penetration butt welds over the entire cross section. Prior to welding, submit for approval a welding plan consisting of the following:

a. Quality Control personnel qualifications. b. Welding Procedure Specifications (WPS). c. Procedure Qualification Records (PCR).

d. Welder Performance Qualification Records (WPQR) with documentation of current welder certification.

e. Sample daily inspection sheet.

f. Type and extent ofNDE to be conducted, as required by the specifications.

[

Perform all Quality Control inspection necessary to ensure the materials

and workmanship meet the requirements of the contract documents.

Correct all deficiencies in materials and workmanship revealed by Quality I

Control and Quality Assurance inspections without additional

compensation. !

Furnish all completed Quality Control inspection documents to the Quality

Assurance representative designated by the State. (

Add the following subsection:

626-3.03 AS-BUILT DRAWINGS. The Contractor shall completely and accurately record all deviations, deletions, additions, and alterations to correctly depict existing utilities and sewer lines and appurtenances as actually installed. The as-built construction shall be marked on a clean set of plan sheets dedicated solely to keeping of this as-built information. When sanitary sewer construction is complete, the Contractor shall certifY the accuracy of the sanitary sewer as­ builts in writing and deliver the documents to the Engineer.

626-4.01 METHOD OF MEASUREMENT. Add the following: As-builts will not be measured for payment and the work will be considered incidental to other work required in this section.

Insulated Sanitary Sewer Conduit located on the bridge includes all pipe jackets, insulation, thermal insulation joint kits, hangers, supports, bracing, couplings, expansion assemblies, and appurtenances as required to install a complete workable system as detailed and required.

Cleanouts will include all work as detailed in the plans and will be measured as units, complete in place.

Connections to existing sewer lines include all work detailed in the plans and as

required to provide watertight connections, including manhole work. Com1ections will be measured as units, complete in place.

Lowering the sewer line will be measured as a complete unit in place and includes all work required for lowering the line including connections to the existing sewer line, installation of bends, pipe, fittings, rigid board insulation, and other work necessary for a complete workable system. Earthwork is incidental.

Air relief includes saddle, fittings, pipe, valve, supports and accessories required to construct an air relief system as detailed.

Backwater Valve will include all work as detailed in the plans and will be measured as units, complete in place.

Removal and or abandonment of existing pipe is considered incidental to other work and no separate payment will be made.

626-5.01 BASIS OF PAYMENT. Delete the second paragraph and substitute the following: Excavation, shoring as required, dewatering as required, import bedding material, backfill, compaction, testing, excess and unusable material disposal, and other earthwork incidentals for construction of sanitary sewers, and all sanitary sewer appurtenances, are included with the various sewer bid items.

Add the following .Pill' items:

2

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I

|P |ay Item |Pay Unit |

|626(3) Insulated Sanitary Sewer Conduit, 10-inch |Linear Foot |

|626( 4) Construct Cleanout |Each |

|626(5) Connect to Existing Sewer Line |Each |

|626(6) Construct Air Relief |Each |

|626(7) Construct Backwater Valve |Each |

|6 |6(8) Construct Valve Manhole |Each |

|62 | | |

| |6(9) Lower Sanitary Sewer Line |Lump Sum |

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Use this Special as reference information, only. Thoroughly review the content. Use only current references. Tailor to the current project.

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