§ 7.5-95. Inspection of sewers.

(1)

City inspection. The developer's contractor will be responsible for the quality, accuracy and workmanship of his completed work. City personnel will visit the job site on a periodic basis and will make spot checks as they deem appropriate. The city shall have the right to review and inspect all construction and may reject any work that does not meet quality control standards.

(2)

Access to project. Authorized representatives of the city, which may include city employees, the city engineer, state or federal agencies, shall have access to the site for inspection at any time.

(3)

Communications during construction. A preconstruction conference will be required for all projects. The developer has sole responsibility for scheduling. The developer, design professional, contractor, and subcontractor(s) are required to meet with the city and all private utilities in this conference. The contractor will notify the city in writing two (2) days before starting construction. The contractor will provide notification by phone any time the work is to be vacated and will provide notice by phone prior to resuming work. The contractor shall request the final inspection. The city inspector may have informal verbal communications with the contractor foreman or superintendent at any time during construction. The city inspector will not direct the actions of contractor's workmen.

(4)

Concealed work. The city inspector may direct that the contractor notify the city and receive inspection approval prior to concealing certain work such as manhole foundations, pipe bedding, tees, bends, service laterals, or other appurtenances. At the city's discretion, the city may require work to be uncovered which was not inspected prior to backfilling.

(5)

Minimum inspection by developer. The following minimum information shall be determined and certified by the engineer:

(a)

Horizontal location. Horizontal location of the line will be checked by measuring as-built distances between manholes and bearings from manhole to manhole.

(b)

Elevation and slope. Elevation of each invert and top of manhole will be measured and recorded. Actual pipe slope will be computed and any segment having less than minimum allowable slope will be rejected and re-done.

(6)

City inspection. Cost for all testing shall be paid for by the developer.

(a)

Manhole construction. Manholes will be visually inspected to check for plugging of lift holes, use of connecting boots, use of joint material, leakage, proper invert construction, proper setting of frame and cover.

(b)

Pipe straightness. Sections of sewer line will be visually checked for straightness. A passing section shall show at least eighty (80) percent of a full circle when observed from one (1) end. Any section which fails this visual test shall be further checked. The section shall have water run through it sufficient to fill any sags that may exist. Then it shall have a television camera pulled through it to check for sags. Any sag holding more than one and one-half inches (1½) of water will require that the pipe be removed and replaced to proper grade after which the section shall be televised again to verify correction. The contractor may propose alternative methods other than televising sewers for the city's approval to determine failing sections of sewers.

(c)

Infiltration. The allowable limit for any section from manhole to manhole will be one hundred (100) gallons per day per inch of pipe diameter per mile of pipe. If any infiltration is present at the most downstream point, then it will be measured using a specially-made weir and measurements will also be made at each upstream manhole that has any visible flow of water. Any individual segment which exceeds the allowable infiltration shall be corrected to within allowable limits.

(d)

Compaction of backfill. Compaction testing may be required for sewers constructed in paved areas or where pavement is planned. A minimum of two (2) tests per five hundred (500) feet of trench line located in roadways will be required. If any of these tests show failing results, then the failing backfill will be removed, re-compacted and re-tested, and one (1) additional area will be tested as well.

(7)

Other testing requirements. The tests listed below shall be performed by the contractor in the presence of the city. The city will be notified at least two (2) days prior to these tests.

(a)

Mandrel test for PVC pipe. Procedure for testing PVC sewer pipe for maximum allowable deflection shall be generally as follows (Mandrel sized to ninety-five (95) percent of the nominal internal pipe diameter):

1.

Completely flush the line making sure the pipe is clean of any mud or trash that would hinder the passage of the mandrel.

2.

During the final flushing of the line, attach a floating block or ball to the end of the mandrel pull rope and float the rope through the line (a nylon ski rope is recommended).

3.

After the rope is threaded through the line, connect the pull rope to the mandrel and place the mandrel in the entrance of the pipe.

4.

Connect a second rope to the back of the mandrel. This will enable the mandrel to be retrieved if excessive deflection is encountered.

5.

Draw the mandrel through the sewer line.

6.

An increasing resistance to pull is an indication of excessive deflection. If this occurs mark the rope to note the location. Televise the sewer section to identify the extent of the problem and develop a plan, subject to city approval, for correcting the problem. The contractor may propose an alternative method other than televising sewers for the city's approval to determine locations of failing sewers.

7.

Retest.

(b)

Air pressure test. A low pressure test of each sewer line section will be conducted by the contractor to check for leaks. The following general procedures will apply (also refer to ASTM specs):

1.

Temporarily plug the line segment between two (2) manholes using plugs having air tight fittings through which low pressure air can be introduced into the pipe segment being tested.

2.

Introduce low pressure air into the test pipe segment until the internal air pressure reaches four and one-half (4.5) psig above ground water pressure, if any.

3.

Wait at least five (5) minutes for air temperature in the test segment to stabilize while internal air pressure remains no less than three and one-half (3.5) psig above ground water pressure.

4.

Bleed internal air pressure to exactly three and one-half (3.5) psig above ground water pressure.

5.

Accurately determine the elapsed time for internal pressure to drop to two and one-half (2.5) psig above ground water pressure.

6.

The air test is acceptable if elapsed time is no less than shown on the following table:

Pipe Diameter (in inches)	Seconds Per 100 Feet of Pipe	Pipe Diameter (in inches)	Seconds Per 100 Feet of Pipe
8	72	27	252
10	90	30	288
12	108	36	360
15	126	42	438
18	144	48	516
21	180	54	588
24	216

 

Air leakage time is based on pipe being damp. If pipe and joints are dry, dampen line if helpful in meeting air test time requirement.

Permanently correct excessive leakage determined by air testing, and repeat operations until the city witnesses a successful test on each line segment.

Upon request, the city may allow substitution of exfiltration test in lieu of air pressure test. If used, the exfiltration test will be conducted with a minimum water head of two (2) feet above the groundwater table and the allowable exfiltration will be limited to one hundred (100) gallons per day per inch diameter of pipe per mile of pipe.

(c)

Manhole testing. All manholes require testing by either the vacuum test or exfiltration test.

1.

Exfiltration test. Manholes which have been backfilled around shall be tested for exfiltration. The minimum test time duration is one (1) hour. Manholes shall be filled with water to the top of ring. The maximum allowable exfiltration rate is two (2) gallons/foot of depth/foot of manhole diameter.

2.

Vacuum test. Vacuum testing of manholes for watertightness may be used in lieu of the exfiltration test prior to backfilling. After temporarily plugging pipe openings and installing the vacuum base on top of the cone, a vacuum of ten (10) inches of Mercury shall be drawn and the vacuum pump shut off. With valves closed, the pressure shall be monitored for a time period of sixty (60) seconds. At the end of the test period, if the vacuum is nine (9) inches or greater, the manhole has passed the test. If the vacuum drops below nine (9) inches, the manhole has failed.

(8)

Final inspection and conditional acceptance. In no circumstances shall any buildings and plumbing fixtures be connected to the sewers until inspected and approved by the city. The contractor shall request in writing a final inspection. This final inspection will generally include spot checks of manholes and sewer lines and a complete overview of the project.

After any discrepancies are corrected, the city will issue a letter, certifying conditional acceptance of the sewer system. This letter shall commence the start of the twelve-month warranty period which is required of the contractor. On projects having phased development, this letter will allow the developer to apply for a permit for the next phase of development.

At the end of twelve (12) months, the subdivision inspection team will again reinspect the entire development. When all discrepancies have been corrected, the city will issue an acceptance letter and will begin perpetual maintenance and operation of the sewerage system.

(9)

Maintenance bond or letter of credit. The developer shall post a maintenance bond or letter of credit of ten (10) percent of the total project cost on the facility for an eighteen-month period after completion and conditional acceptance of the facility by the city for all projects whose costs exceed twenty thousand dollars ($20,000.00).

(10)

Maintenance until final acceptance. It shall be the developer's obligation to provide all maintenance for a twelve-month period after conditional acceptance of the project by the city. At the end of the twelve-month maintenance period the city shall inspect the sewer system, and upon correction by the developer of all deficiencies noted by the city, the city will accept the sewer system for operation.

(Ord. No. 32-98, § 1, 8-27-98; Ord. No. 50-98, § 1, 1-7-99; Ord. No. 04-02, § 2, 1-3-02)