Outsourcing storm water system cleaning saves time, money for Salem/Hope Creek
The storm water collection system at Public Service Electric & Gas Co.`s (PSE&G) Salem/Hope Creek generating stations has not been cleaned since installation 20 years ago. When faced with the need to clean and repair the system, PSE&G found it did not have the manpower or equipment needed to clean the 14,000 feet of line involved. But, Video Pipe Services Inc., Newfield, N.J., did.
The project objective was to meet pollutant standards for solids discharged into the receiving stream, the adjacent Delaware River. Flow consisted of storm water runoff from precipitation, and contents included solids washed into catch basins and piping. No exotic chemicals were involved.
The line was primarily reinforced concrete in diameters from 12 inches to 60 inches, most in the 18- to 30-inch range, and most laid in 8-foot sections. Manhole-to-manhole lengths were from 30 to 300 feet.
Before starting the project, Video`s employees were submitted to PSE&G`s standard health examination, police and other security clearances. Next came a three-day plant school to familiarize personnel with alarms, tagging, radiation checks and a general overview of nuclear plant processes in order to relieve safety and health concerns.
Contractor crew members were then given badge clearance to enter and exit the plant through an airport-type security and radiation checkpoint. At each work site, atmosphere safety was assured by monitoring the confined space with a detector, checking for oxygen deficiency and toxic gases, including methane, hydrogen sulfide and carbon monoxide.
Each length of pipe was cleaned by pushing a jet hose up-line from the downstream manhole. As the nozzle was retracted by a vehicle-mounted power winch, water from the jetter cleared debris, flushing it to gather against a temporary screen at the downstream manhole. One to 10 passes of the jet hose were required to clear the lines.
Power was variable, up to 2,000 pounds per square inch, and volume fluctuated from 65 to 80 gallons per minute. The temporary screen, sized to pass both normal flow and cleaning water, trapped loosened solids down to one-eighth of an inch. Most particles captured were stone and ice-control sands.
A vacuum/jet rig was used to remove material from the collection point. Some pipes were half full of material, and one 48-inch diameter line was three-fourths full. All accumulations were hauled by the jetter/vacuum vehicle to a nearby authorized disposal site.
Once the cleanout was completed, the same jetter was used to thread a winch-connected electric cable through the line. Its end was attached to a closed-circuit television camera. Views of the interior pipe were monitored by technicians in the video truck, and color video tapes were produced for permanent reference. Section-by-section integrity, infiltration points, cleanliness and flow velocity were recorded.
PSE&G directed the contractor to air-test all joints to pinpoint infiltration. Those visibly leaking or non-supportive of the air pressure were repaired using chemical pressure to quickly form a long-lasting water-impervious barrier.
PSE&G said all pertinent pollution regulations have been met and the cleaned sewer system has shown enough capacity to allow the utility to pave on-site parking lots. Atmospheric dirt and dust have been substantially reduced and sewer loads remain within original design parameters.
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PSE&G chose to outsource storm water system cleaning and repairs, saving itself time and money while meeting environmental regulations for its Salem/Hope Creek nuclear generation stations.