Sewer Renewal (Rehabilitation) Flashcards
Why is there a need for sewer Rehabilitation?
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
Why must a physical survey of a collection system be conducted before a sewer Rehabilitation project can start?
A physical survey of a collection system must be conducted to determine the condition of the system.
Page 269
Why must the present maintenance program be reviewed before the start of a sewer rehabilitation program?
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
Why is there an emphasis on the reduction of hydraulic infiltration/inflow loads on sewer systems and treatment facilities?
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
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?
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
Why must the possible surcharge potential for a flow metering location be determined?
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
Smoke testing is not effective under which conditions or circumstances?
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
What types of areas are suitable for dyed water flooding?
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
What is the most effective method of identification and quantification of defects in sewer pipes
Closed circuit television is the most effective method of identification and quantification of defects in sewer pipes
Page 283
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?
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.
Page 284
The normal process of setting priorities and reaching decisions on the rehabilitation of a sewer system involves the quantitative evaluation of which factors?
Involves the quantitative evaluation of the following factors:
*Performance of Sears.
*Sewer capacity.
*Consequence of failure. *Sewer condition.
*Cost.
Page 286
What cost should be considered when evaluating the cost effectiveness of an I/I rehabilitation program?
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
What is the oldest and most common method of sewer Rehabilitation?
The oldest and most common method of sewer Rehabilitation is excavation & replacement.
Page 288
What are the disadvantages of sewer Rehabilitation by excavation and replacement?
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
What is the most common method of ceiling leaking pipe joint and circumferential cracks?
The use of chemical grouting page 290
How can the success of chemical grouting be tested?
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
When are trenchless sewer Rehabilitation methods used?
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
List three broad types of trenchless pipeline Rehabilitation methods.
Different types of trenchless pipeline Rehabilitation methods include: *Cured-in-place pipe. *Slip-lining. *In-line replacement. Page 296 - 300
What is shotcrete?
Shotcrete is sometimes referred to as gunite:
a mixture of sand, cement and water applied by air pressure
Page 299.
What is Insituform?
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
List the basic materials and pieces of equipment required for a typical Insituform installation.
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
What is the purpose of the insitucutter?
The purpose of the Insitucutter is to cut out lining material in the areas in the sewer defined as service taps
Page 306
What happens after Preparatory cleaning is completed on an Insituform sewer rehabilitation job?
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
In the Insituform lining technique, where is the inversion platform erected?
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
