Sewer Renewal (Rehabilitation)

Question 1

Why is there a need for sewer Rehabilitation?

Answer 1

Sewers need Rehabilitation to restore structural integrity and to control excessive additional infiltration and inflow flows during periods of heavy rainfall or high ground water conditions.
Page 267

Question 2

Why must a physical survey of a collection system be conducted before a sewer Rehabilitation project can start?

Answer 2

A physical survey of a collection system must be conducted to determine the condition of the system.
Page 269

Question 3

Why must the present maintenance program be reviewed before the start of a sewer rehabilitation program?

Answer 3

The present sewer maintenance program must be reviewed before the start of a sewer rehabilitation program to ensure a coordinated effort of Maintenance and Rehabilitation.
Page 275

Question 4

Why is there an emphasis on the reduction of hydraulic infiltration/inflow loads on sewer systems and treatment facilities?

Answer 4

The main reason for the emphasis on reducing hydraulic infiltration/inflow loads on sewer systems and treatment facilities is that these loads increased treatment cost, result in the bypassing of untreated waste water to the environment ( sanitary sewer overflows (SSOs) and combined sewer overflows (CSOs)) can result in structural failure of weakened a weekend collection systems. Page 275

Question 5

The purpose of flow monitoring as part of a sewer system evaluation is to measure variations in flow components over time to identify Peak and minimum flow conditions. The flow monitor phase is set up to identify and measure which three flow components?

Answer 5

The purpose of flow monitoring as part of a sewer system evaluation is to measure variations and Flo components over time to identify Peak and minimum flow conditions. The flow monitoring phase is set up to identify and measure the three flow components: period base flow, infiltration, and inflow.
Page 275

Question 6

Why must the possible surcharge potential for a flow metering location be determined?

Answer 6

The possible surcharge potential for a flow metering location must be determined because surcharging results in uneven flow or backflow conditions, which will reduce faulty flow meter readings. Page 276

Question 7

Smoke testing is not effective under which conditions or circumstances?

Answer 7

Smoke testing is not effective during High ground water conditions or in sewers where sags or water traps or suspected or where sewers Flow full.
Smoke testing is ineffective when the ground is
Saturated.
Frozen.
Covered with snow and
Under windy conditions.
Page 280

Question 8

What types of areas are suitable for dyed water flooding?

Answer 8

Dyed-water flooding is applicable for:
Storm water drains.
Drainage ditches, streams and water ponding areas.
Yard drains,area way drains, Foundation drains, roof drains and abandoned building sewers.
Specific problem areas identified in other tests for which additional data are needed.
Page 280

Question 9

What is the most effective method of identification and quantification of defects in sewer pipes

Answer 9

Closed circuit television is the most effective method of identification and quantification of defects in sewer pipes
Page 283

Question 10

In setting up a sewer system rehabilitation program the cost to implement various strategies must be calculated. What are the four courses of action that can be taken?

Answer 10

Four courses of action that must be taken:
*Maintain the system as finances permit.
*Replace the worst components to the extent possible.
*Relieve deteriorating or overloaded segments were conditions and finances permit.
*Rehabilitate to the extent possible.
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Question 11

The normal process of setting priorities and reaching decisions on the rehabilitation of a sewer system involves the quantitative evaluation of which factors?

Answer 11

Involves the quantitative evaluation of the following factors:
*Performance of Sears.
*Sewer capacity.
*Consequence of failure. *Sewer condition.
*Cost.
Page 286

Question 12

What cost should be considered when evaluating the cost effectiveness of an I/I rehabilitation program?

Answer 12

The cost effectiveness of an I/I rehabilitation program includes:
* Survey and Rehabilitation cost.
*Construction and capital cost. *Operation and maintenance cost.
A comparison of the cost to transport and treat the rainfall induced I/I with the cost to eliminate it will yield the most cost-effective solution
Page 286

Question 13

What is the oldest and most common method of sewer Rehabilitation?

Answer 13

The oldest and most common method of sewer Rehabilitation is excavation & replacement.
Page 288

Question 14

What are the disadvantages of sewer Rehabilitation by excavation and replacement?

Answer 14

The disadvantages of sewer Rehabilitation by excavation and replacement include the same problem that are common to all Construction:
*Traffic disruption and control. *Disruption of properties. *Paving damage.
*Shoring requirements. *Excavation dewatering.
*Noise and restoration.
Disadvantages unique to excavation and replacement include:
* Maintaining flow.
*Removal and disposal of old pipes.
*Effect on other utilities. Impact of shoring left in place. In addition this method is normally more expensive and the disruption of traffic and the normal lifestyle of people living or working in the areas much longer than with other methods.
Finally there is a greater danger associated with this method due to the large excavations and possible impact on other utilities.
Page 288

Question 15

What is the most common method of ceiling leaking pipe joint and circumferential cracks?

Answer 15

The use of chemical grouting page 290

Question 16

How can the success of chemical grouting be tested?

Answer 16

The success of chemical grouting can be tested by a low-pressure air test or by digging up a joint to see if the ground performed as expected.
Page 290

Question 17

When are trenchless sewer Rehabilitation methods used?

Answer 17

Trenchless sewer Rehabilitation methods are used when soil or groundwater conditions make it difficult to use open cut construction methods and in downtown areas where disruption to businesses and the public is an important consideration.
Page 296

Question 18

List three broad types of trenchless pipeline Rehabilitation methods.

Answer 18

Different types of trenchless pipeline Rehabilitation methods include: 
*Cured-in-place pipe. 
*Slip-lining.
*In-line replacement.
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Question 19

What is shotcrete?

Answer 19

Shotcrete is sometimes referred to as gunite:
a mixture of sand, cement and water applied by air pressure
Page 299.

Question 20

What is Insituform?

Answer 20

Insituform is a method of pipe liner Rehabilitation consisting of the installation of new pipe within the old pipe without excavation.
The process involves the use of a polyester-fiber felt tube, lined on one side with polyurethane and fully impregnated with a liquid thermal setting risen.
Page 304

Question 21

List the basic materials and pieces of equipment required for a typical Insituform installation.

Answer 21

The basic materials and pieces of equipment required for a typical instituform installation include the following:
*The inversion platform. 
*The inversion tube.
*Inversion elbow. 
*The portable mixer. 
*The Transformer pump. 
*The vacuum pump. 
*The wet down conveyor system. 
*The lay flat hose. 
*The hold back rope. 
*The water supply line. 
*The water control valve. 
*A circulating pump. 
*The boiler and heat exchanger unit. 
*The insitucutter
*Thermocouple
*The polyurethane-coated, polyester-fiber felt liner. 
*The polyester resin. 
*The catalyst.
Page 304

Question 22

What is the purpose of the insitucutter?

Answer 22

The purpose of the Insitucutter is to cut out lining material in the areas in the sewer defined as service taps
Page 306

Question 23

What happens after Preparatory cleaning is completed on an Insituform sewer rehabilitation job?

Answer 23

After cleaning the internal inspection and evaluation team makes an inspection of the line to verify that the cleaning is complete and also to record on a record on a TV log the location of all line deficiencies and service Connections.
In addition to the TV log the line is videotaped.
Page 308

Question 24

In the Insituform lining technique, where is the inversion platform erected?

Answer 24

In the Insituform lining technique, the inversion platform is erected over the point of insertion of the liner into the sewer being lined usually over in manhole.
Page 308

Question 25

How can a liner be tested for damages after it has been unpacking from its shipping container?

Answer 25

A liner can be tested by attaching a vacuum pump to the bag and evacuating the entrapped air from the felt liner material.
It would be impossible to draw and maintain a vacuum with the system if the liner were damaged.
Page 309

Question 26

What safety precautions should be taken during the installation and curing processes of an insituform job?

Answer 26

Safety precautions that should be taken during the installation and curing processes of an Insituform job include:
protection of workers Spectators and
equipment from hot water. Anytime workers enter manholes all confined space procedures must be followed. The strong volatile styrene fumes created during this process must be avoided.
Page 312

Question 27

In what ways are pipe liners an effective method of repairing or reconditioning a sewer system?

Answer 27

Liners Can Be an Effective method of repairing or reconditioning is sewer system by providing a new smooth pipe to carry the Wastewater.
Frequently liners are installed to control excessive infiltration exfiltration and root intrusion. Selection of this method depends on whether this procedure is simplier, quicker and more economical in comparison with other techniques.
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Question 28

What information is included in a letter to homeowners explaining a sliplinig project?

Answer 28

A letter to homeowners explaining a Slip Sliding project should include the following information:

• Why the project is necessary. *What is planned.
• What is expected to be accomplished by the operation.
• Any direct cost that the homeowners must pay.

The letter should state that the homeowner may be temporarily inconvenience during construction and also explain the benefits that will result from the construction project.
Also include a form legally prepared for the homeowner signature.
This form provides authorization to do any and all work necessary to accomplish the project.
It also guarantees that the premises will be restored to as near the original state as possible at no additional cost to the homeowner.
Page 313

Question 29

Why should a sewer be televised before slip lining?

Answer 29

A sewer should be televised before sliplining to locate laterals any misaligned joints and any other discrepancies that will need to be corrected before the actual lining takes place.
Page 313

Question 30

What equipment is needed to prepare and weld the polyurethane pipes together?

Answer 30

Equipment needed to prepare and well the polyurethane pipes together includes Fusion Joiner Jigs and mobile carts to handle both the main line pipe and the laterals, a butt Fusion tool or squaring tool, and heating faces (both flat and part round) for heating the saddles.
Pulling heads and tapping or coring tools are needed plus accessories to adapt to the various sizes of pipe that will be used.
Page 313

Question 31

How many crews are recommended and what are their duties for a sliplining project?

Answer 31

Three crews are recommended for a slip lining project:

• One Crew assembles the liner.
• And Excavating crew digs the pull hole at a predetermined location.
• Another crew prepares the pulling equipment and pulley apparatus in the manhole into which the liner will be pulled. Page 314

Question 32

Why should the liner be marked at 50 foot intervals before being pulled into the sewer?

Answer 32

The liner should be marked at 50 foot intervals before pulling into the sewer as a precautionary measure.
If there is a pulling problem and the pipe hangs up in the line it maybe necessary to dig up the pipe.
By marking at 50 foot intervals you can easily locate the pulling head in the line
Page 314

Question 33

When sliplining laterals, where are holes commonly dug for the liner?

Answer 33

When sliplining lateral dig holes where the lateral connects to the main line and where the lateral enters the house.
Page 317

Question 34

Why is the space where the pipe connects to the manhole sealed?

Answer 34

The space where the pipe connects to the manhole is sealed to prevent infiltration or exfiltration at the manhole.
Page 318

Question 35

What are the three methods of chemically grouting service connections to eliminate/infiltration inflow (I/I)?

Answer 35

Three methods include:
*Pump the sewer system full of grout using a conventional Packer and then clean with an auger to restore to full service.
*Use a sewer service sealng unit called a “sewer sausage”. *Use a specialized miniature camera and Packer unit called a “camera packer”.
Page 319

Question 36

When manhole interior walls are to be repaired using a coating process, how should the surfaces be prepared to ensure the coating system will result in future protection?

Answer 36

When Manhole interior walls are to be repaired using a coating process, surface preparation is extremely important to ensure the coating system will result in future protection. Thoroughly, clean the walls to remove the grease, sludge, mineral deposits, lose concrete or mortar and debris.
Prepare the Surface by water or abrasive blasting, repairing cracks and applying a moisture tolerant primer (if the concrete cannot be dried sufficiently)
All rough areas should be patched to provide a smooth surface which will receive the coating to be applied.
Page 325

Question 37

When using a coating process to repair manhole interior walls, what coating materials are available that can provide protection from hydrogen sulfide attack (corrosion)?

Answer 37

When using a coating process to repair manhole interior walls, various epoxy, acrylic, plastic, and polyurethane base Coatings are available that can provide protection from hydrogen sulfide attack (corrosion)
These waterproof and corrosion resistant Coatings can be applied to Brick, block and precast concrete manholes and bases.
The choice of coating material depends on the chemistry of the particular situation encountered.
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