Waste Collection Systems

Transcription

1 Waste Collection Systems System Maintenance and Repair Maintenance and Repair Training Objectives To gain an understanding of: System Maintenance and Repair vocabulary System Maintenance and Repair techniques Proper operation of clearing and cleaning equipment Proper sewer line repair procedures Air Binding The stoppage of flow in a pipe or pump due to the presence of air released from water. 1

2 Air Gap An open vertical drop, or vertical empty space, between a drinking water supply and the point of use. Air gap devices are used to provide adequate space above the top of a manhole and the end of the hose from the fire hydrant. Balling A method of hydraulically cleaning a sewer or storm drain by using the pressure of a water head to create a high cleansing velocity of water around the ball. Special sewer cleaning balls have an outside tread that causes them to spin or rotate, resulting in a "scrubbing" action of the flowing water along the pipe wall. Blockage (1) Partial or complete interruption of flow as a result of some obstruction in a sewer. (2) When a collection system becomes plugged and the flow backs up, it is said to have a "blockage." 2

3 BUCKET A special device designed to be pulled along a sewer for the removal of debris from the sewer. Flow Line The top of the wetted line, the water surface or the hydraulic grade line of water flowing in an open channel or partially full conduit. Hand Rod A sewer rod that can be inserted manually into a sewer to clear a stoppage or to prevent a stoppage from developing. 3

4 Hydraulic Cleaning Cleaning pipe with water under enough pressure to produce high water velocities. (1) Using a high-velocity cleaner. (2) Using a ball, kite or similar sewer cleaning device. (3) Using a scooter. (4) Flushing Kite A device for hydraulically cleaning sewer lines. Resembling an airport wind sock and constructed of canvas-type material. The kite increases the velocity of a flow at its outlet to wash debris ahead of it. Manhole Jack A device used to guide the tag line into the sewer without causing unnecessary wear and provide support as the tag line is pulled back and forth. 4

5 Mechanical Cleaning Clearing pipe by using equipment that scrapes, cuts, pulls or pushes the material out of the pipe. Mechanical cleaning devices or machines include bucket machines, power rodders and hand rods. Porcupine A sewer cleaning tool the same diameter as the pipe being cleaned. The tool is a steel cylinder having solid ends with eyes cast in them to which a cable can be attached and pulled by a winch. Many short pieces of cable or bristles protrude from the cylinder to form a round brush. Power Rodder A machine designed to remove roots, grease, and other materials from pipes. 5

6 Predictive Maintenance The ability to identify problem areas before breakdowns or blockage of flow occurs. Predictive maintenance is the end product of effective preventive maintenance. Preventative Maintenance Regularly scheduled servicing of machinery or other equipment using appropriate tools, tests and lubricants. This type of maintenance can prolong the useful life of equipment and machinery and increase its efficiency by detecting and correcting problems before they cause a breakdown of the equipment. Scooter A sewer cleaning tool whose cleansing action depends on the development of high water velocity around the outside edge of a circular shield. The metal shield is rimmed with a rubber coating and is attached to a framework on wheels (like a child's scooter). The angle of the shield controls the cleansing velocity of the water flowing around the shield. 6

7 Sliplining A sewer rehabilitation technique accomplished by inserting flexible polyethylene pipe into an existing deteriorated sewer. Swab A circular sewer cleaning tool almost the same diameter as the pipe being cleaned. As a final cleaning procedure after a sewer line has been cleaned with a porcupine, a swab is pulled through the sewer and the flushing action of water flowing around the tool cleans the line. Annular Space A ring-shaped space located between two circular objects. For example, the space between the outside of a pipe liner and the inside of a pipe. 7

8 Cross Braces Shoring members placed across a trench to hold other horizontal and vertical shoring members in place. Slope The slope or inclination of a sewer trench excavation is the ratio of the vertical distance to the horizontal distance or "rise over run." Spoil Excavated material such as soil from the trench of a sewer. 8

9 Surcharge Sewers are surcharged when the supply of water to be carried is greater than the capacity of the pipes to carry the flow. The surface of the wastewater in manholes rises above the top of the sewer pipe, and the sewer is under pressure or a head, rather than at atmospheric pressure. Vacuum Test A testing procedure that places a manhole under a vacuum to test the structural integrity of the manhole. Purpose of C&M Program: Minimize number of system stoppages. Minimize number of customer odor complaints. Minimize number of lift station failures. Maximize system life and operational efficiency. 9

10 Stoppage Types: Roots Grease Debris Broken pipe Failed joint Clearing/Cleaning Methods: Rodding Sewer Ball High-Velocity Cleaner Bucket Machine Kite or Bag Scooter Flushing Scraper Chemical Root Treatment Rodding Equipment Truck or trailer mounted Hand rods Cutting tools Uses Used to clear roots and other stoppages in pipes with diameter of 15 inches or less. 10

11 Sewer Ball Equipment: Different size balls Tagline winch Cable Reels Water tank truck Dump pickup Uses: Removal of sand, grit, debris and grease in areas without possibility of basement flooding. High-Velocity Cleaner: Truck or trailer mounted hydro jet Nozzles Easement rollers Uses: Good for cleaning and clearing grease, sand, grit, debris. Bucket Machine Equipment: Power bucket machine Truck loader Dump truck Operating rollers and tools Uses: Removes dirt and debris from large diameter pipe 11

12 Kite or Bag Equipment: Water tank truck Dump truck Power drum winch machine Uses: Removes decaying debris and grease. Use cautiously in areas with basements and steep grades. Scooter Equipment: Water tank truck Dump truck Tag line Power winch Uses: Removes heavy debris and grease Use cautiously in areas with basements and steep grades. Flushing Equipment: Water truck Fire hose Uses: Moves decaying organic material downstream 12

13 Chemical Root Treatment Applied as dry, foam or liquid depending on product. Destroys root system and causes roots to decay. Inhibits root re-growth producing long lasting results. Hydrogen Sulfide Control Hazards of H 2 S Toxic Corrosive Explosive Formation of H 2 S Sulfur reducing bacteria Lack of dissolved oxygen Sulfur compounds Warmer temperatures Slower flows Hydrogen Sulfide Control Chemical Control of H 2 S Chlorine Hydrogen Peroxide Pure Oxygen Air Lime Sodium Hydroxide Iron Salts Calcium Nitrate 13

14 Post Repair System Testing Air Testing Conducted to determine pipe integrity following a repair. Air will leak through smaller cracks than water, therefore better to detect vapor leaks that can attract roots. Test pressure is between 3 and 5 psi. Post Repair System Testing Vacuum Test Manhole pressure tests are usually negative pressure tests -2 to -3 psi or -14 to -21 kpa Maintain pressure above -3 psi (-21 kpa) to avoid damage to manhole. Post Repair System Testing Water Testing Used to test new sewer line for possible leakage. Must plug all lines going to building sewer systems. Fill manhole and pipe with water and mark start time and level. Let stand for 2 hours or 2 foot drop in level. Acceptable exfiltration rate is 450 GPD/in/mile or less. 14

15 Post Repair System Testing Mandrel Testing Performed on flexible pipe installations following backfill and compaction. Measures pipe deflection and joint offsets Maximum of 5% deflection is acceptable. Pull mandrel assembly through pipe to test diameter and pipe joints System Repairs Main Line Repair Utilities must be marked before digging. Set up traffic control before working in street. Verify location of repair and measurements before digging. Watch trench for cross trenches with unmarked utilities. System Repairs Main Line Repair Safe spoil for backfill if of good quality Pile spoil at least 2 feet but preferably 4 feet from trench edge. Use probe to determine depth of pipe. When within 6 inches of pipe, dig by hand. 15

16 System Repairs Main Line Repair Tools should be lowered into trench with bucket and rope. Remove all loose soil from beneath pipe to make room for new gravel bedding material. Compact backfill by mechanical tampers or water jetting. System Repairs Cured in place pipe lining (CIPP) Trenchless method of repairing leaking joints and cracks in smaller diameter pipes. System Repairs Grouting Performed in areas where excavation is difficult to correct infiltration or exfiltration. Equipment: Air compressor Chemical pump Water pump Sleeve packer 16

17 System Repairs Grouting Sealing chemical is typically a hydrophilic polymer. When water is mixed with polymer, it expands to ~10 time its original volume and cures to a strong but flexible finish. Camera is used to place the sleeve packer properly. Camera should be on downstream side of joint being repaired to avoid water build-up blocking the image. 17