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RT 337 Presentation - Final
- 1. Bowers Hill Interceptor Force Main Section 1 Emergency Repair August 26, 2014
- 2. • Break was identified on July 24 at 12:45 PM. – Emergency Designation due to high risk – Excessive rainfall during initial response – Spill contained 7am the next morning – Event overflow 919,500 gallons – Complex repair required 24/7 operation – Repair complete in 9 days – Force main back online August 2 Summary of Event 2
- 3. Route 337 Pressure Reducing Station Service Area 3
- 6. Initial Dewatering Setup (cont.) 6
- 8. Pressure Reducing Station (PRS) 8
- 9. Contingency Pumping and Dewatering System 9
- 10. Force Main Installed to Pump/Dewater to PRS 10
- 11. 1300’ of Right of Way Widened for Equipment 11
- 12. 300’ of 36” HDPE Pipe was Fused and Laid in 1 Week 12
- 13. Upstream Line stop Excavation over 15’ deep 13
- 15. Removed 36” Gate Valve and 12’ of pipe 15
- 16. Pipe Failure 16
- 17. Pipe Failure 17
- 18. New 36” Plug Valve, DI Pipe, and Solid Sleeves were installed 18
- 20. Questions?
Hinweis der Redaktion
- 36-inch ductile iron force main at the 337 Pressure Reducing Station - July 24 10 below grade - flow could not be diverted High risk of a major catastrophic failure - immediately obtain Emergency Designation Line stops, bypass, pumps, and engineering support
- Route 337 Pressure Reducing Station near Chesapeake Square Mall Describe Service Area Cedar Rd Great Bridge BLVD and Battlefield BLVD
- IDENTIFY THE BREAK SITE Wastewater flowed into VDOT Storm water ditch to the right of the picture. Initial spill estimate was 500 gpm Crews responded immediately to assess situation and contain the leak. Over 5” of rainfall in the 337 service area within a 24 hour period.
- First day Sandbags were utilized and a temporary pit was dug out for initial containment efforts.
- 8” Diesel Godwin Pump mobilized discharge through a flexible hose into the pressure reducing station
- Over 5” of rain fell in the RT 337 service area that evening which doubled the flow for the service area and impacted the initial response Go over the 337 Service Area and that both Downtown Suffolk and Southern Chesapeake (Separate Service Areas) were also inundated
- Simply Put a PRS Lowers Pressures on it’s Suction side to help upstream stations overcome friction losses in the Force Main
- An Extensive Bypass and Containment System was built to recover as much WASTEWATER as possible. Video Shows the contingency pumping and dewatering system 8” pump, 6” pump, 20,000 gallon sediment trailer, and 2 pumps and associated valving to pump from the sediment trailer to the PRS. We were relying on the Pressure Reducing Station to maintain vacuum conditions to keep the spill contained for over 1 week. If PRS pumps lost prime or additional force main failure occurred, pumping system would contain leak.
- This discharge FM from sedimentation tank hard piped to the Pressure Reducing Station Fusing together approximately 100’ of 12” HDPE and associated support and cribbing for the temporary Force Main. HRSD Employees put in many hours of hard work throughout this event. pumping out surrounding ditches, assisting TA Sheets and Godwin on equipment mobilization, emergency bypass pumping, and adjusting system set points.
- Right of Way had to be widened and matting material installed to get specialized equipment in place.
- The entire area remained heavily saturated from the July 24th rain event Over 300’ of 36” HDPE Pipe had to be fused, set, supported, and tied in 12 hour shift rotations with a 12 man crew during the day and a 10 man crew during the night. 4 excavators, 2 front end loaders, and multiple dump trucks worked 24/7 throughout the repair to accomplish this massive task.
- 50 yards of concrete were used for Lines Stop Thrust Blocks *ADD Picture Over 15’ deep Ground water was maintained with 5 diesel pumps Incoming Groundwater varied from 500-2500 gpm throughout the repair
- Identify that because this system was a force main that there was no need for a bypass pump.
- Valve installed with dresser couplings on both sides Bolts and nuts from the dresser couplings had completely failed WR&A along with SPS performed an initial evaluation. As bolts failed sewage may have leaked around gasket and created a corrosive environment within the poly wrap Pipe had deteriorated between the weld on joints Approximately 12’ of pipe was removed. Severe Corrosion was present on the pipe between the Mainline Valve and the welded-on restraint collars
- PIPE IS LOCATED UPSIDE DOWN IN PICTURE Notice the missing hardware from the dresser coupling restraints.
- PIPE IS LOCATED UPSIDE DOWN IN PICTURE The upstream section of pipe had two 4” holes corroded completely through the pipe wall. Deteriorated components were replaced with new pipe, valve, and ductile iron sleeves. Cathodic Protection was designed and installed for this site. This is the failure location on the upstream piece of pipe from the Mainline Valve. There were two 4” holes located at 5 and 7 o-clock. It was observed that the ground water level was at the same elevation as the failure.
- Solid Sleeves, instead of dresser couplings, were installed with a new Plug Valve and piping.
- HRSD has identified 6 other locations on the Bowers Hill Interceptor Force Main Section I and II that similar installation methods were likely used. These Pipes were Relocated back in 1988 (26 years ago) for the construction of Interstate 664 Brown and Caldwell will be leading the effort in future condition assessment and related analysis.